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Sample records for binary trojan asteroid

  1. THE PUZZLING MUTUAL ORBIT OF THE BINARY TROJAN ASTEROID (624) HEKTOR

    SciTech Connect

    Marchis, F.; Cuk, M.; Durech, J.; Castillo-Rogez, J.; Vachier, F.; Berthier, J.; Wong, M. H.; Kalas, P.; Duchene, G.; Van Dam, M. A.; Hamanowa, H.; Viikinkoski, M.

    2014-03-10

    Asteroids with satellites are natural laboratories to constrain the formation and evolution of our solar system. The binary Trojan asteroid (624) Hektor is the only known Trojan asteroid to possess a small satellite. Based on W. M. Keck adaptive optics observations, we found a unique and stable orbital solution, which is uncommon in comparison to the orbits of other large multiple asteroid systems studied so far. From lightcurve observations recorded since 1957, we showed that because the large Req = 125 km primary may be made of two joint lobes, the moon could be ejecta of the low-velocity encounter, which formed the system. The inferred density of Hektor's system is comparable to the L5 Trojan doublet (617) Patroclus but due to their difference in physical properties and in reflectance spectra, both captured Trojan asteroids could have a different composition and origin.

  2. Observations of Candidate Binary Asteroids in the Jovian Trojan and Hilda Populations

    NASA Astrophysics Data System (ADS)

    Sonnett, Sarah M.; Mainzer, Amy K.; Grav, Tommy; Masiero, Joseph R.; Bauer, James M.; Kramer, Emily A.

    2016-10-01

    Jovian Trojans (hereafter, Trojans) are asteroids in stable orbits at Jupiter's L4 and L5 Lagrange points, and Hilda asteroids are inwards of the Trojans in 3:2 mean-motion resonance with Jupiter. Due to their special dynamical properties, observationally constraining the formation location and dynamical histories of Trojans and HIldas offers key input for giant planet migration models. A fundamental parameter in assessing formation location is the bulk density - with low-density objects associated with an ice-rich formation environment in the outer solar system and high-density objects typically linked to the warmer inner solar system. Bulk density can only be directly measured during a close fly-by or by determining the mutual orbits of binary asteroid systems. With the aim of determining densities for a statistically significant sample of Trojans and Hildas, we are undertaking an observational campaign to confirm and characterize candidate binary asteroids published in Sonnett et al. (2015). These objects were flagged as binary candidates because their large NEOWISE brightness variations imply shapes so elongated that they are not likely explained by a singular equilibrium rubble pile and instead may be two elongated, gravitationally bound asteroids. We are obtaining densely sampled rotational light curves of these possible binaries to search for light curve features diagnostic of binarity and to determine the orbital properties of any confirmed binary systems by modeling the light curve. We present preliminary results from the follow-up campaign of these candidates, including estimates on the densities of objects that appear to be in binary systems and the binary fraction for Trojans and Hildas.

  3. Search for Binary Trojans

    NASA Astrophysics Data System (ADS)

    Noll, Keith S.; Grundy, W. M.; Ryan, E. L.; Benecchi, S. D.

    2015-11-01

    We have reexamined 41 Trojan asteroids observed with the Hubble Space Telescope (HST) to search for unresolved binaries. We have identified one candidate binary with a separation of 53 milliarcsec, about the width of the diffraction limited point-spread function (PSF). Sub-resolution-element detection of binaries is possible with HST because of the high signal-to-noise ratio of the observations and the stability of the PSF. Identification and confirmation of binary Trojans is important because a Trojan Tour is one of five possible New Frontiers missions. A binary could constitute a potentially high value target because of the opportunity to study two objects and to test models of the primordial nature of binaries. The potential to derive mass-based physical information from the binary orbit could yield more clues to the origin of Trojans.

  4. A Troop of Trojans: Photometry of 24 Jovian Trojan Asteroids

    NASA Astrophysics Data System (ADS)

    French, Linda M.; Stephens, R. D.; Coley, D. R.; Wasserman, L. H.; La Rocca, D.; Vilas, F.

    2013-10-01

    Because of their greater distance from the Sun, the Jovian Trojans have been less studied than main belt asteroids. Although they are numerous (nearly 6000 have well determined orbits as of July 2013), the Trojans remain mysterious in many ways. Their spectra are unlike those of any meteorites in terrestrial collections. The spectra and the low albedos of Trojans, however, bear a strong resemblance to those of cometary nuclei (Abell et al. 2005; Fornasier et al. 2007; Emery et al. 2011). The Nice Model (Morbidelli et al. 2005; 2009) predicts that the Trojans may well be objects that originated with today's Kuiper Belt Objects. The rotation of asteroids larger than ~50 km in diameter seems to be determined largely by collisions, while that of smaller bodies is shaped primarily by YORP forces and torques (Pravec et al. 2008). We are surveying the rotation properties of Trojans to see whether similar trends are present. We find an abundance of slow rotators, including the first documented tumbler among the Trojans. We present 24 new Trojan lightcurves, mostly from objects ranging from 30-50 km in diameter. We also discuss observations of five sub-20 km Trojans, whose rotation properties are consistent with cometary densities. This research was supported by National Science Foundation Grant AST-1212115, by NASA Grant NNX-08AO29G, and by an American Astronomical Society Small Research Grant.

  5. Long periodic perturbations of Trojan asteroids.

    NASA Astrophysics Data System (ADS)

    Érdi, B.

    1987-03-01

    The motion of the Trojan asteroids is studied in the elliptic restricted three-body problem of the Sun-Jupiter-asteroid system. Long periodic perturbations of the orbital elements are discussed. Relations between dynamical parameters are considered and comparisons are made with Bien's and Schubart's results.

  6. Long periodic perturbations of Trojan asteroids

    NASA Astrophysics Data System (ADS)

    Erdi, B.

    The motion of the Trojan asteroids is studied in the elliptic restricted three-body problem of the Sun-Jupiter-asteroid system. Long periodic perturbations of the orbital elements are discussed. Relations between dynamical parameters are considered and comparisons are made with Bien's and Schubart's results.

  7. Rotation lightcurves of small jovian Trojan asteroids

    NASA Astrophysics Data System (ADS)

    French, Linda M.; Stephens, Robert D.; Coley, Daniel; Wasserman, Lawrence H.; Sieben, Jennifer

    2015-07-01

    Several lines of evidence support a common origin for, and possible hereditary link between, cometary nuclei and jovian Trojan asteroids. Due to their distance and low albedos, few comet-sized Trojans have been studied. We present new lightcurve information for 19 Trojans ≲ 30 km in diameter, more than doubling the number of objects in this size range for which some rotation information is known. The minimum densities for objects with complete lightcurves are estimated and are found to be comparable to those measured for cometary nuclei. A significant fraction (∼40%) of this observed small Trojan population rotates slowly (P > 24 h), with measured periods as long as 375 h (Warner, B.D., Stephens, R.D. [2011]. Minor Planet Bull. 38, 110-111). The excess of slow rotators may be due to the YORP effect. Results of the Kolmogorov-Smirnov test suggest that the distribution of Trojan rotation rates is dissimilar to those of Main Belt Asteroids of the same size. Concerted observations of a large number of Trojans could establish the spin barrier (Warner, B.D., Harris, A.W., Pravec, P. [2009]. Icarus 202, 134-146), making it possible to estimate densities for objects near the critical period.

  8. Discovery of an Earth Trojan Asteroid

    NASA Astrophysics Data System (ADS)

    Connors, M. G.; Wiegert, P.; Veillet, C.

    2011-12-01

    Near-Earth asteroid 2010 TK7 was discovered by the Widefield Infrared Survey Explorer (WISE) satellite on October 1, 2010. With followup observations from the Canada-France-Hawaii telescope, it has been shown to be the first known Trojan companion of Earth, in an orbit with large librational and epicyclic range about the leading L4 Lagrange point. The orbit is very chaotic, with transitions between triangular Lagrange points ("jumping") and temporary residence at the L3 (opposite) Lagrange point being possible. Nevertheless, this appears to be "stable" chaos with a restricted range of behaviors. Chaos limits the ability to determine the behavior of the real body over long periods of time, but clone studies can indicate the probable lifetime and origins. We speculate that a larger population of Earth Trojans may exist. Trojans of low inclination, and similar related co-orbital objects, could present low energy (delta-V) opportunities for space missions, including potentially as part of the future manned program aim of sending astronauts to asteroids. 2010 TK7 is not a suitable target due to its inclination of nearly 21 degrees, but its discovery may provide an impetus for further searches for co-orbital objects, with Trojan searches likely to also detect horseshoe or co-orbital asteroids. Horseshoe objects can come closer to Earth than Trojans, which could be a mission consideration. The possibility of obtaining primordial material from such objects would be of scientific and possibly economic interest.

  9. JHK photometry of selected Trojan and Hilda asteroids

    NASA Technical Reports Server (NTRS)

    Smith, Dale W.; Johnson, Paul E.; Buckingham, William L.; Shorthill, Richard W.

    1992-01-01

    No entirely satisfactory match has been established between the present JHK photometry of selected Hilda and Trojan asteroids and photometry for both main belt asteroids and laboratory samples. It is noted that while the leading Trojans and Hildas exhibit similar and homogeneous JHK colors, the trailing Trojans appear to be more heterogeneous. Charcoal and magnetite provide the best match in terms of JHK colors.

  10. Light-Curve Survey of Jupiter Trojan Asteroids

    NASA Astrophysics Data System (ADS)

    Duffard, R.; Melita, M.; Ortiz, J. L.; Licandro, J.; Williams, I. P.; Jones, D.

    2008-09-01

    Trojan asteroids are an interesting population of minor bodies due to their dynamical characteristics, their physical properties and that they are relatively isolated located at the snow-line The main hypotheses about the origin of the Jupiter Trojans assumed that they formed either during the final stages of the planetary formation (Marzari & Scholl 1998), or during the epoch of planetary migration (Morbidelli et al. 2005), in any case more than 3.8 Gy. ago. The dynamical configuration kept the Trojans isolated from the asteroid Main Belt throughout the history of the Solar System. In spite of eventual interactions with other populations of minor bodies like the Hildas, the Jupiter family comets, and the Centaurs, their collisional evolution has been dictated mostly by the intrapopulation collisions (Marzari et al. 1996, 1997). Therefore, the Jupiter Trojans may be considered primordial bodies, whose dynamical and physical properties can provide important clues about the environment of planetary formation. The available sample of Jupiter Trojans light-curves is small and mainly restricted to the largest objects. According to the MPC-website (updated last in March 2006), the present sample of rotation periods and light-curve-amplitudes of the Jupiter Trojan asteroids is composed by 25 objects with some information about their periods and by 10 of them with only an amplitude estimation. A survey of contact binary Trojan asteroids has been done by Mann et al. 2007, where they have recorded more than 100 amplitudes from sparse-sampled light-curves and very-wellresolved rotational periods. More than 2000 Trojan asteroids have been discovered up to date, so, there is an urgent need to enlarge the sample of intrinsic rotation periods and accurate light-curve amplitudes and to extend it to smaller sizes. Results and Discusions We requested 26 nights of observation in the second semester of 2007, to begin with the survey. They were scheduled for the following instruments

  11. A Genetic Cluster of Martian Trojan Asteroids

    NASA Astrophysics Data System (ADS)

    Christou, Apostolos

    2013-10-01

    Trojan asteroids lead 60 degrees ahead (L4) or trail 60 degrees behind (L5) a planet's position along its orbit. The Trojans of Jupiter and Neptune are thought to be primordial remnants from the solar system's early evolution (Shoemaker et al., 1989; Sheppard et al., 2006). Mars is the only terrestrial planet known to host stable Trojans (Scholl et al., 2005) with ~50 km-sized objects expected to exist (Tabachnik and Evans, 1999). I identified 6 additional candidate Martian Trojans within the Minor Planet Center database, including three with multi-opposition orbits. 100 dynamical clones for each of the three asteroids were integrated for 100 Myr under a force model that included the Yarkovsky effect. All clones persisted as L5 Trojans of Mars, implying that their residence time is longer still. This is further supported by recent Gyr numerical integrations (de la Fuente Marcos and de la Fuente Marcos, 2013). The number of stable Martian Trojans is thus raised to 7, 6 of which are at L5. To investigate this asymmetry, I apply a clustering test to their orbits and compare them with the Trojan population of Jupiter. I find that, while Jupiter Trojans are spread throughout the domain where long-term stability is expected, L5 martian Trojans are far more concentrated. The implication is that these objects may be genetically related to each other and to the largest member of the group, 5261 Eureka. If so, it represents the closest such group to the Earth's orbit, still recognizable due to the absence of planetary close encounters which quickly scatter NEO families (Schunova et al., 2012). I explore the origin and nature of this `Eureka cluster', including the thesis that its members are products of the collisional fragmentation and/or rotational fission of Trojan progenitors. I constrain the cluster's age under these scenarios and argue that collisions may be responsible for the observed paucity of km-sized objects. Finally, I discuss how the hypothesis of a genetic

  12. The composition of the Trojan asteroids

    NASA Technical Reports Server (NTRS)

    Gradie, J.; Veverka, J.

    1980-01-01

    Consideration is given to the composition of those Trojan asteroids, Hilda asteroids and 944 Hidalgo with very low albedos and spectral reddening between 0.4 and 1.1 microns with respect to the C asteroids, termed RD objects. It is proposed that the albedo and reddening of these objects can be explained by the presence of very opaque, very red, polymer-type organic compounds structurally similar to kerogen, presumably resulting from Fischer-Tropsch-type reactions in the early solar nebula. The spectra and various mixtures of powdered montmorillonite, magnetite, coal-tar residue containing kerogen substances and carbon black are shown to provide a good match to the RD asteroid spectral properties. It is suggested that the nonsoluble carbonaceous residue may have required lower temperatures for its formation and preservation than carbonaceous materials in the carbonaceous chondrites and C asteroids, and thus explain the absence of RD objects closer than 4 AU from the sun.

  13. Rotation Properties of Small Jovian Trojan Asteroids

    NASA Astrophysics Data System (ADS)

    French, Linda M.; Stephens, Robert D.; James, David; Coley, Daniel R.; Warner, Brian D.; Rohl, Derrick

    2016-10-01

    Jovian Trojan asteroids are of interest both as objects in their own right (we have no spectral analogs among meteorite samples) and as possible relics of Solar System formation. Asteroid lightcurves can give information about processes that have affected a group of asteroids; they can also give information about the density of the objects when enough lightcurves have been collected. We have been carrying out a survey of Trojan lightcurve properties for comparison with small asteroids and with comets. In a recent paper (French et al. 2015) we presented evidence that a significant number of Trojans have rotation periods greater than 24 hours. We will report our latest results and compare them with results of sparsely-sampled lightcurves from the Palomar Transient Factory (Waszczak et al. 2015). LF, RS, and DR were visiting astronomers at Cerro Tololo Interamerican Observatory, operated by AURA under contract with the NSF, and with the SMARTS Consortium at CTIO. This research was sponsored by NSF Planetary Astronomy grant 1212115.ReferencesFrench, L.M. et al. 2015. Icarus 254, pp. 1-17.Waszczak, A. et al. 2015. A.J. 150, Issue 3, I.D. 35.

  14. Rotational properties of L4 Trojan asteroids from K2

    NASA Astrophysics Data System (ADS)

    Ryan, Erin L.; Woodward, Charles E.; Sharkey, Benjamin N. L.

    2016-10-01

    Our understanding of solar system formation is undergoing a renaissance as new planetary systems are found, often unlike our own. Many questions now ask how the giant planets and their satellite systems accreted and if there is evidence that they migrated to new orbital positions. One of the keys to understanding these questions within our own solar system is the Jupiter Trojan population which is co-orbital with Jupiter. The two Trojan clouds at the stable L4 and L5 Lagrangian points are in orbits which are stable over the age of the Solar System, unlike many other present epoch small body populations. Planetary migration models suggest that the Trojan asteroids, and the dynamically hot (i.e. "scattered"), population of Kuiper Belt objects originate from the same region in the early solar system. While these objects would have started with the same compositions, establishing compositional linkages is challenging and complicated due to a paucity of distinct and easily identifiable mineralogical features in the optical, where these objects are the brightest. While the surface compositions and colors of the Trojans match objects in the inner solar system, as well as the Kuiper Belt, physical characterization of this large population of objects has been scarce. During Campaign 6 in late 2015, the 115 square degree K2 spacecraft field of view overlapped with the L4 Trojan cloud, allowing for long term monitoring. We report on the fitted rotational periods and lightcurve amplitudes from 56 Trojan asteroids that were observed for an average of 11 days by K2. We find ~20% of objects have rotational periods longer than 50 hours and ~40% of the objects have lightcurves with shapes characteristic of contact binary systems.

  15. Photometric Observations of Martian Trojan Asteroids

    NASA Astrophysics Data System (ADS)

    Borisov, Galin; Christou, Apostolos; Unda-Sanzana, Eduardo

    2016-07-01

    We present R filter photometry of the Martian Trojan asteroids (101429) 1998 VF31 and (385250) 2001 DH47, carried out with the 2-m RCC and 1.3-m SMARTS telescopes during 11 nights in 2015 November and 2016 January. A periodogram analysis of the lightcurves suggests a rotation period of P = 7.70h with a low amplitude (A < 0.1 mag) for 1998 VF31 and P = 3.97h with amplitude A ~ 0.6mag for 2001 DH47.

  16. Trojan, Hilda, and Cybele asteroids - New lightcurve observations and analysis

    NASA Technical Reports Server (NTRS)

    Binzel, Richard P.; Sauter, Linda M.

    1992-01-01

    Lightcurve observations of 23 Trojan, Hilda, and Cybele asteroids are presently subjected to a correction procedure for multiple-aspect lightcurves, followed by a quantitative, bias-corrected analysis of lightcurve amplitude distributions for all published data on these asteroids. While the largest Trojans are found to have a higher mean-lightcurve amplitude than their low-albedo, main-belt counterparts, the smaller Trojans and all Hildas and Cybeles display lightcurve properties resembling main-belt objects. Only the largest Trojans have retained their initial forms after subsequent collisional evolution; 90 km may accordingly represent a transitional magnitude between primordial objects and collision fragments.

  17. Voyage to Troy: A mission concept for the exploration of the Trojan asteroids

    NASA Astrophysics Data System (ADS)

    Saikia, S.; Das, A.; Laipert, F.; Dapkus, C.; Kendall, J.; Bowling, T.; Steckloff, J.; Holbert, S.; Graves, K.; Anthony, T.; Bobick, R.; Huang, Y.; Stuart, J.; Longuski, J.; Minton, D.

    2014-07-01

    red). Hektor is currently thought to be a contact binary with a companion in an unusually inclined orbit and presents itself as a target with diverse knowledge to offer. The possibility of potentially gathering data from a Hilda asteroid en route to the Trojans is also being investigated. The mission would consist of the rendezvous of one or two Trojan asteroids along with further flybys. Candidate instruments are a thermal mapper, multispectral imagers, gamma-ray, neutron, and UV-spectrometers, and a LIDAR. The mission is designed within the constraints of NASA New Frontiers mission with a less than 10-year trajectory. The mission concept will help in the future Trojan mission concept studies.

  18. BINARY CANDIDATES IN THE JOVIAN TROJAN AND HILDA POPULATIONS FROM NEOWISE LIGHT CURVES

    SciTech Connect

    Sonnett, S.; Mainzer, A.; Masiero, J.; Bauer, J.; Grav, T.

    2015-02-01

    Determining the binary fraction for a population of asteroids, particularly as a function of separation between the two components, helps describe the dynamical environment at the time the binaries formed, which in turn offers constraints on the dynamical evolution of the solar system. We searched the NEOWISE archival data set for close and contact binary Trojans and Hildas via their diagnostically large light curve amplitudes. We present 48 out of 554 Hilda and 34 out of 953 Trojan binary candidates in need of follow-up to confirm their large light curve amplitudes and subsequently constrain the binary orbit and component sizes. From these candidates, we calculate a preliminary estimate of the binary fraction without confirmation or debiasing of 14%-23% for Trojans larger than ∼12 km and 30%-51% for Hildas larger than ∼4 km. Once the binary candidates have been confirmed, it should be possible to infer the underlying, debiased binary fraction through estimation of survey biases.

  19. A CCD comparison of outer Jovian satellites and Trojan asteroids

    NASA Technical Reports Server (NTRS)

    Luu, Jane X.

    1991-01-01

    The eight small outer Jovian satellites are not as well known as the brighter, more illustrious Galilean satellites. They are divided into two groups, each containing four satellites; the inner group travels in prograde orbits while the outer group travels in retrograde orbits. From the distinct orbital characteristics of the two groups, most of the theories of their origin involve the capture and breakup of two planetesimals upon entry into the atmosphere of proto-Jupiter. Their proximity to the Trojans asteroids has led to conjectures of a link between them and the Trojans. However, Tholen and Zellner (1984) found no red spectrum among six of the satellites and postulated that they were all C-type objects; therefore, they were unlikely to be derivatives of the Trojan population. Charge-coupled device (CCD) photometry and spectroscopy of the eight outer Jovian satellites obtained from 1987 to 1989 and a comparison between these eight satellites and the Trojan asteroids are presented.

  20. The perturbations of the orbital elements of Trojan asteroids

    NASA Astrophysics Data System (ADS)

    Erdi, B.

    1981-08-01

    An asymptotic solution for the cylindrical coordinates of Trojan asteroids is derived by using a three-variable expansion method in the elliptic restricted three-body problem. The perturbations of the orbital elements are obtained from this solution by applying the formulas of the two-body problem. The main perturbations of the mean motion are studied in detail.

  1. Jupiter Magnetospheric Orbiter and Trojan Asteroid Explorer in EJSM

    NASA Astrophysics Data System (ADS)

    Sasaki, Sho; Fujimoto, Masaki; Yano, Hajime; Takashima, Takeshi; Kasaba, Yasumasa; Funase, Ryu; Tsuda, Yuichi; Kawaguchi, Junichiro; Kawakatsu, Yasuhiro; Mori, Osamu; Morimoto, Mutsuko; Yoshida, Fumi; Takato, Naruhisa

    The international mission to explore the Jovian system is planned as Europa Jupiter System Mission (EJSM) aiming at the launch in 2020. EJSM consists of (1) the Jupiter Europa Orbiter (JEO) by NASA, (2) the Jupiter Ganymede Orbiter (JGO) by ESA, and (3) the Jupiter Magnetospheric Orbiter (JMO) studied by JAXA (Japan Aerospace Exploration Agency). In February 2009, NASA and ESA decided to continue the study of EJSM as a candidate of the outer solar system mission. In JAXA, a mission plan combining Trojan asteroid explorer with JMO started. According to the mission plan, as the main spacecraft flies by Jupiter, it will deploy the JMO satellite around Jupiter. Then the main will target one (or two) Trojan asteroids. JMO is a spin-stabilized satellite which will have magnetometers, low-energy plasma spectrome-ters, medium energy particle detectors, energetic particle detectors, electric field / plasma wave instruments, an ENA imager, an EUV spectrometer, and a dust detector. Collaborating with plasma instruments on board JEO and JGO, JMO will investigate the fast-rotating huge mag-netosphere to clarify the energy procurement from the rotation of Jupiter to the magnetosphere and to clarify the interaction between the solar wind and the magnetosphere. JAXA started the study of a solar power sail for deep space explorations. In addition to the function of a solar sail (photon propulsion), the solar power sail system has very efficient ion engines where electric power is produced solar panels within the sail. Currently we are studying a mission to Jupiter and Trojan asteroids using a large (100m-scale) solar power sail that can transfer large payload as far as Jupiter. Trojan asteroids, which orbit around Jupiter's Lagrangian points, are primitive bodies with information of the early solar system as well as raw solid materials of Jovian system. Proposed instruments for the Trojan spacecraft are cameras, IR spectrometers, XRS, a laser altimeter, and a small surface rover

  2. Spectral Emissivity (6 – 38 µm) of Jupiter's Trojan Asteroids

    NASA Astrophysics Data System (ADS)

    Martin, Audrey; Emery, Joshua P.; Lindsay, Sean S.

    2016-10-01

    Jovian Trojan asteroids, located in Jupiter's stable Lagrange points, are an extensive population of primitive bodies in the Solar System. Previous work in the visible and NIR shows Trojans have featureless, red-sloped spectra and low albedos, making mineralogical characterization difficult. However, it has been shown that three Trojans exhibit silicate emissivity features in the thermal IR (6 – 38 μm Emery et al. 2006, Icarus 182). The detected features indicate the presence of fine-grained (micron-sized) silicate dust on the surfaces, and closely resemble spectral features measured of cometary comae. We hypothesize that Trojan surface mineralogy is fairly uniform and is similar to comet dust. The principal goal of this work is, therefore, to derive primary surface mineralogy from thermal emission spectra. We present thermal IR spectra of 12 Trojans observed with NASA's Spitzer space telescope, using the InfraRed Spectrograph (IRS) in Staring Mode from June 2006 to June 2007. Eight objects were observed over the 5.2 – 38 µm spectral range, and four objects over the 7.5 – 38 µm range. Using the NEATM thermal model, we have computed size, albedo, and beaming parameter for the 12 Trojans. Results for these physical parameters are comparable to those derived from WISE data (Grav et al. 2011, ApJ 742 (1); Grav et al. 2012, ApJ 759 (49)). There are, however, some discrepancies, especially with 2797 Teucer. The emissivity spectra fall into groups that directly correlate with the red and less-red spectral slope groupings described in Emery et al. (2011, ApJ, 141(1)). Strong 10 µm emission features appear in each object, suggesting the presence of fine-grained silicates. Features found between 12-13 µm, and 18-19 µm are also observed in all spectra. We will present these new Trojan asteroid data with mineralogical estimates derived from the emissivity spectra.

  3. Small Jovian Trojan Asteroids: An Excess of Slow Rotators

    NASA Astrophysics Data System (ADS)

    French, Linda M.

    2016-01-01

    Several lines of evidence support a common origin for, and possible hereditary link between, cometary nuclei and jovian Trojan asteroids. Due to their distance and low albedos, few comet-sized Trojans have been studied. We discuss the rotation properties of Jovian Trojan asteroids less than 30 km in diameter. Approximately half of the objects discussed here were studied using densely sampled lightcurves (French et al. 2015a, b); Stephens et al. 2015), and the other half were sparse lightcurves obtained by the Palomar Transient Factory (PTF; Waszcazk et al. 2015). A significant fraction (~40%) of the objects in the ground-based sample rotate slowly (P > 24h), with measured periods as long as 375 h (Warner and Stephens 2011). The PTF data show a similar excess of slow rotators. Only 5 objects in the combined data set have rotation periods of less than six hours. Three of these fast rotators were contained in the data set of French et al. these three had a geometric mean rotation period of 5.29 hours. A prolate spheroid held together by gravity rotating with this period would have a critical density of 0.43 gm/cm3, a density similar to that of comets (Lamy et al. 2004). Harris et al. (2012) and Warner et al. (2011) have explored the possible effects on asteroid rotational statistics with the results from wide-field surveys. We will examine Trojan rotation statistics with and without the results from the PTF.

  4. Lightcurve Analysis of an Unbiased Sample of Trojan Asteroids

    NASA Astrophysics Data System (ADS)

    Molnar, Lawrence A.; Haegert, Melissa, J.; Hoogeboom, Kathleen M.

    2008-06-01

    Lightcurve observations of ten Trojan asteroids made at the Calvin Observatory are reported: 1143 Odysseus, 1208 Troilus, 2920 Automedon, 3709 Polypoites, 5144 Achates, 5638 Deikoon, (7352) 1994 CO, (34746) 2001 QE91, (38050) 1998 VR38, and (48438) 1989 WJ2. Synodic rotation periods were determined for all but (7352) 1994 CO, which showed no significant variation. The sample was unbiased with regard to period, and has a median value, 18.9 hours, significantly longer than for similarly sized main-belt objects. This may be evidence for a lower average mass density among the Trojans.

  5. The composition of the Eureka family of Martian Trojan asteroids

    NASA Astrophysics Data System (ADS)

    Borisov, Galin; Christou, Apostolos; Bagnulo, Stefano

    2016-10-01

    The so-called Martian Trojan asteroids orbit the Sun just inside the terrestrial planet region. They are thought to date from the earliest period of the solar system's history (Scholl et al, Icarus, 2005). Recently, Christou (Icarus, 2013) identified an orbital concentration of Trojans, named the "Eureka" cluster after its largest member, 5261 Eureka. This asteroid belongs to the rare olivine-rich A taxonomic class (Rivkin et al, Icarus, 2007; Lim et al, DPS/EPSC 2011). Unlike asteroids belonging to other taxonomies (e.g. C or S), no orbital concentrations or families of A-types are currently known to exist. These asteroids may represent samples of the building blocks that came together to form Mars and the other terrestrial planets but have since been destroyed by collisions (Sanchez et al, Icarus, 2014, and references therein).We have used the X-SHOOTER echelle spectrograph on the ESO VLT KUEYEN to obtain vis-NIR reflectance spectra of asteroids in the cluster and test their genetic relationship to Eureka. During the presentation we will show the spectra, compare them with available spectra for Eureka itself and discuss the implications for the origin of this cluster and for other olivine-dominated asteroids in the Main Belt.Based on observations made with ESO Telescopes at the La Silla-Paranal Observatory under programme ID 296.C-5030 (PI: A. Christou). Astronomical Research at Armagh Observatory is funded by the Northern Ireland Department of Culture, Arts and Leisure (DCAL).

  6. Proper elements and stability of the Trojan asteroids.

    NASA Astrophysics Data System (ADS)

    Burger, C.; Pilat-Lohinger, E.; Dvorak, R.; Christaki, A.

    We now know 413 Trojan asteroids which are moving close to the Lagrangian equilibrium points L4 (246) and L5 (167) of Jupiter. The orbits of all these asteroids were integrated numerically for 10 million years in the dynamical model of the outer planetary system (Jupiter, Saturn, Uranus and Neptune). The proper elements were derived numerically for these asteroids and compared to other available studies (e.g. Bien & Schubart, Milani). We then computed for the whole integration time the RMS of the elements semi-major axes, eccentricities and inclinations. The 3-dimensional graphs (RMS versus proper inclination and proper eccentricities) show the special location of the asteroids with positive Lyapunov exponents.

  7. Photometry of Main Belt and Trojan asteroids with K2

    NASA Astrophysics Data System (ADS)

    Szabó, Gyula; Kiss, Csaba; Pal, Andras; Szabo, Robert

    2016-10-01

    Due to the failure of the second reaction wheel, a new mission was conceived for the otherwise healthy Kepler space telescope. In the course of the K2 Mission, the telescope is staring at the plane of the Ecliptic, hence thousands of Solar System bodies cross the K2 fields, usually causing extra noise in the highly accurate photometric data.We could measure the first continuous asteroid light curves, covering several days wthout interruption, that has been unprecedented to date. We studied the K2 superstamps covering the M35 and Neptune/Nereid fields observed in the long cadence (29.4-min sampling) mode. Asteroid light curves are generated by applying elongated apertures. We investigated the photometric precision that the K2 Mission can deliver on moving Solar System bodies, and determined the first uninterrupted optical light curves of main-belt and Trojan asteroids. We use thed Lomb-Scargle method to find periodicities due to rotation.We derived K2 light curves of 924 main-belt asteroids in the M35 field, and 96 in the path of Neptune and Nereid. Due to the faintness of the asteroids and the high density of stars in the M35 field, 4.0% of the asteroids with at least 12 data points show clear periodicities or trend signalling a long rotational period, as opposed to 15.9% in the less crowded Neptune field. We found that the duty cycle of the observations had to reach ˜ 60% in order to successfully recover rotational periods.The derived period-amplitude diagram is consistent to the known distribution of Main Belt asteroids. For Trojan asteroids, the contribution of our 56 objects with newly determined precise period and amplitude is in the order of all previously known asteroids. The comparison with earth-based determinations showed a previous bias toward short periods and has also proven that asteroid periods >20 hour can be unreliable in a few cases because of daylight time and diurnal calibrations. These biases are avoided from the space. We present an unbiased

  8. PARIS to Hektor, A Mission to the Jovian Trojan Asteroids

    NASA Astrophysics Data System (ADS)

    Gold, R. E.; Ensworth, C. B.; McNutt, R. L.; Ostdiek, P. H.; Prockter, L. M.

    2005-12-01

    PARIS (Planetary Access with Radioisotope Ion-drive System) spacecraft enable a new class of missions to the outer solar system. The high power-to-mass ratio of new radioisotope power systems enables New-Frontiers class missions that carry a significant a science payload to new destinations. The PARIS spacecraft take advantage of the high-efficiency of Stirling radioisotope generators (SRGs) or new thermoelectric converters to provide the power for an electric propulsion system. These low-thrust missions launched to a high C3 are especially effective for exploring objects in shallow gravity wells. The Jovian Trojan asteroids are very primitive bodies located near the Jovian L4 and L5 Lagrange points and are discussed as targets in the Solar System Decadal Survey. There are estimated to be more than 105 Jovian Trojans greater than 1 km in diameter. We consider a PARIS mission that can reach the asteroids in less than 5 years, orbit 624 Hektor, the largest of the Jovian Trojans, and go on to orbit at least one other nearby object. The candidate payload for this mission includes wide-field and narrow-field cameras, a UV-Vis-IR spectrograph, gamma-ray and neutron spectrometers, and plasma and energetic particle spectrometers. About 900 W of power are required. The launch mass would be slightly less than 1000 kg. The < 5 year trip time is dependent on having the next generation power sources with a specific power of > 8W/kg.

  9. The theory of the Trojan asteroids. V

    NASA Astrophysics Data System (ADS)

    Garfinkel, B.

    1985-05-01

    E. W. Brown conjectured (1911) that the family of the long-periodic orbits in the Trojan case of the restricted problem of three bodies terminates in an asymptotic orbit passing through the Lagrangian point L3 at t = ±∞. In 1977 the author showed that such an orbit deviates from L3 by the epicyclic term mg(±∞). It is shown here that g(±∞) ≠ 0, so that the Brown conjecture regarding L3 is false. Contrary to what Brown believed, there is an entire family of homoclinic orbits, doubly asymptotic to short-periodic orbits around L3. The kinematics of the homoclinic family is investigated here in some detail.

  10. Is Jupiter's Moon Amalthea a Captured Trojan Asteroid?

    NASA Astrophysics Data System (ADS)

    Prentice, Andrew J.

    In 2002 the Galileo spacecraft discovered that the small irregular Jovian moon Amalthea is a porous assemblage of rock and ice. Its bulk density is ~1 g/cc. This is much less than the value ~3.8 g/cc expected of the mixture of rock and metal that would form at this Jovian orbit had Amalthea moon condensed from a gas ring shed by the proto-Jovian cloud (Prentice 2001 Earth Moon Planets 87 11). Thus rather than being a native moon of Jupiter and especially because of its small size relative to the Galilean satellites Amalthea is probably a captured asteroid. Prentice and ter Haar (1979 Nature 280 300) had predicted Amalthea to be a C-type asteroid. Galileo has found Amalthea to be even less dense than the porous main-belt C-asteroid Mathilde so suggesting the presence of ice. Most likely therefore Amalthea originally condensed as a planetesimal within the gas ring shed by the proto-Solar cloud at the orbit of Jupiter. The predicted bulk chemical composition by mass is asteroidal rock (65%) graphite (1%) and water ice (34%) [see Prentice in URL: www.lpi.usra.edu/meetings/mercury01]. The zero-porosity density is 1.8 g/cc. Amalthea is simply a first cousin of the Trojan asteroids of Jupiter.

  11. Is Amalthea a Captured Trojan Asteroid of Jupiter?

    NASA Astrophysics Data System (ADS)

    Prentice, Andrew J. R.

    2005-01-01

    In 2002 the Galileo spacecraft discovered that the small irregular Jovian moon Amalthea is a porous assemblage of rock and ice. Its bulk density is ~1 g/cc. This is much less than the value ~3.8 g/cc expected of the mixture of rock and metal that would condense at its distance from Jupiter had Amalthea formed from a gas ring shed by the proto-Jovian cloud (Prentice 2001 Earth Moon Planets 87 11). Thus rather than being a native moon of Jupiter (and especially because of its small size relative to the Galilean satellites) Amalthea is probably a captured asteroid. Prentice and ter Haar (1979 Nature 280 300) had predicted Amalthea to be a C-type asteroid. Galileo has found Amalthea to be even less dense than the porous main-belt C-asteroid Mathilde so suggesting the presence of some ice. Most likely therefore Amalthea originally condensed as a planetesimal from the gas ring shed by the proto-Solar cloud at the orbit of Jupiter. The predicted bulk chemical composition by mass is asteroidal rock (65%) graphite (1%) and water ice (34%) [see Prentice 2001 in URL: www.lpi.usra.edu/meetings/mercury01]. The zero-porosity density is 1.8 g/cc. Amalthea is simply a first cousin of the Trojan asteroids of Jupiter.

  12. Is Amalthea a Captured Trojan Asteroid of Jupiter?

    NASA Astrophysics Data System (ADS)

    Prentice, Andrew J.

    In 2002 the Galileo spacecraft discovered that the small irregular Jovian moon Amalthea is a porous assemblage of rock and ice. Its bulk density is ~1 g/cc. This is much less than the value ~3.8 g/cc expected of the mixture of rock and metal that would condense at its distance from Jupiter had Amalthea formed from a gas ring shed by the proto-Jovian cloud (Prentice 2001 Earth Moon Planets 87 11). Thus rather than being a native moon of Jupiter (and especially because of its small size relative to the Galilean satellites) Amalthea is probably a captured asteroid. Prentice and ter Haar (1979 Nature 280 300) had predicted Amalthea to be a C-type asteroid. Galileo has found Amalthea to be even less dense than the porous main-belt C-asteroid Mathilde so suggesting the presence of some ice. Most likely therefore Amalthea originally condensed as a planetesimal from the gas ring shed by the proto-Solar cloud at the orbit of Jupiter. The predicted bulk chemical composition by mass is asteroidal rock (65%) graphite (1%) and water ice (34%) [see Prentice 2001 in URL: www.lpi.usra.edu/meetings/mercury01]. The zero-porosity density is 1.8 g/cc. Amalthea is simply a first cousin of the Trojan asteroids of Jupiter.

  13. Is Amalthea a Captured Trojan Asteroid of Jupiter?

    NASA Astrophysics Data System (ADS)

    Prentice, Andrew J.

    In 2002 the Galileo spacecraft discovered that the small irregular Jovian moon Amalthea is a porous assemblage of rock and ice. Its bulk density is ~1 g/cc. This is much less than the value ~3.8 g/cc expected of the mixture of rock and metal that would condense at its distance from Jupiter had Amalthea formed from a gas ring shed by the proto-Jovian cloud (Prentice 2001 Earth Moon Planets 87 11). Thus rather than being a native moon of Jupiter (and especially because of its small size relative to the Galilean satellites) Amalthea is probably a captured asteroid. Prentice and ter Haar (1979 Nature 280 300) had predicted Amalthea to be a C-type asteroid. Galileo has found Amalthea to be even less dense than the porous main-belt C-asteroid Mathilde so suggesting the presence of some ice. Most likely therefore Amalthea originally condensed as a planetesimal from the gas ring shed by the proto-Solar cloud at the orbit of Jupiter. The predicted bulk chemical composition by mass is asteroidal rock (65%) graphite (1%) and water ice (34%) [see Prentice 2001 in URL: www.lpi.usra.edu/meetings/mercury01]. The zero-porosity density is 1.8 g/cc. Amalthea is simply a first cousin of the Trojan asteroids of Jupiter

  14. Lightcurves of Jovian Trojan Asteroids from the Center for Solar System Studies: L4 Greek Camp and Spies

    NASA Astrophysics Data System (ADS)

    Stephens, Robert D.; Coley, Daniel R.; Warner, Brian D.; French, Linda, M.

    2016-10-01

    Jovian Trojan asteroids larger than ~ 30 km were studied from the Center for Solar System Studies (CS3, MPC U81). Lightcurves for 30 Trojan asteroids in the L4 (Greek) cloud were between May and June 2016. These were mostly from the L4 "Greek" cloud, but several were L5 "Trojan" cloud lightcurves not previously published.

  15. Spectral Investigation of Binary Asteroids

    NASA Astrophysics Data System (ADS)

    Birlan, Mirel; Nedelcu, D.; Descamps, P.; Berthier, J.; Marchis, F.; Merouane, S.

    2008-09-01

    The number of binary asteroids increased in a significant manner during the last years. Multiple types of observations obtained in adaptive optics, photometry, and radar, allow the rethinking not only the dynamics of the asteroids, but also their physics. The spectroscopy of a binary system can play a key role for establish the mineralogical composition of components, and implicitly the range of their density. By the application of these considerations to the physical and dynamical models, the physical parameters such as the macro-porosity or the "rubble pile” structures could be derived. Observations of binary asteroid (854) Frostia, and binary candidates (1333) Cevenola, and (3632) Chaplin were carried out in the 0.8-2.5 µm spectral range using SpeX/IRTF in LowRes mode. The asteroids present features in both 1 and 2 µm regions, suggesting the presence of silicates in the surface composition. The analysis of slopes, band strengths, and the most probable mineralogical models will be presented.

  16. Trojan Asteroids Observed from GMARS and Santana Observatories: 2009 October - December

    NASA Astrophysics Data System (ADS)

    Stephens, Robert D.

    2010-04-01

    Lightcurves for six Trojan asteroids were obtained from Santana and GMARS Observatories from 2009 October to December: 588 Achilles, 1583 Antilochus, 2456 Palamedes, 3548 Eurybates, 3564 Talyhybius, and 3793 Leonteus.

  17. Japanese mission plan for Jupiter system: The Jupiter magnetospheric orbiter and the Trojan asteroid explorer

    NASA Astrophysics Data System (ADS)

    Sasaki, S.; Fujimoto, M.; Yano, H.; Takashima, T.; Kasaba, Y.; Takahashi, Y.; Kimura, J.; Funase, R.; Mori, O.; Tsuda, Y.; Campagnola, S.; Kawakatsu, Y.

    2011-10-01

    In the future Jupiter system study, Coordinated observation of Jovian magnetosphere is one of the important targets of the mission in addition to icy satellites, atmosphere, and interior of Jupiter. JAXA will take a role on the magnetosphere spinner JMO (Jupiter Magnetospheric Orbiter), in addition to JGO (Jupiter Ganymede Orbiter) by ESA and JEO (Jupiter Europa Orbiter) by NASA. We will combine JMO with a proposed solar sail mission of JAXA for Jupiter and one of Trojan asteroids. Since Trojan asteroids could be representing raw solid materials of Jupiter or at least outer solar system bodies, involvement of Trojan observation should enhance the quality of Jupiter system exploration.

  18. Testing Migration of the Jupiter Trojan Asteroids in the Lab

    NASA Astrophysics Data System (ADS)

    Poston, Michael; Blacksberg, Jordana; Brown, Mike; Carey, Elizabeth; Carlson, Robert; Ehlmann, Bethany; Eiler, John; Hand, Kevin; Hodyss, Robert; Mahjoub, Ahmed; Wong, Ian

    2015-11-01

    Today’s Jupiter Trojan asteroids may have orininated in the Kuiper Belt (eg. Morbidelli et al. Nature 2005, Nesvorny et al. ApJ 2013) and migrated to capture at their present locations. If this is the case, it is expected that their surfaces will contain chemical traces of this history. No distinct spectral bands have been conclusively identified in the literature, however, visible and near-infrared spectra of Kuiper Belt, Centaur, and Trojan populations each show two sub-populations distinguished by their spectral slopes (Brown et al. ApJL 2011; Emery et al. AJ 2011). The slopes are all positive (or “red”), steepest in the Kuiper Belt, and least steep in the Trojan population. Here we test the hypothesis that the asteroids formed spanning a stability line for a critical substance; in this case we test sulfur, as H2S. The hypothesis is that irradiating mixed ices containing H2S will result in a refractory residue of steeper slope than the same composition without the H2S. We have simulated this history in the Minos chamber at the Icy Worlds Simulation Laboratory at NASA’s Jet Propulsion Laboratory. Ices that will be discussed include a 3:3:3:1 mixture of H2S: NH3: CH3OH: H2O and a 3:3:1 mixture of NH3: CH3OH: H2O. After deposition at 50 K, the ices were irradiated with a beam of 10 keV electrons to form the refractory crust. The ices were then warmed (while continuing irradiation) to 120 K and observed for several days. Reflectance spectra were collected throughout the experiment in the visible and infrared. The spectral slope increased dramatically after irradiation of the mixture containing H2S, while the spectral slope for the mixture without any sulfur changed very little. This is consistent with sulfur being the critical component determining which of the spectral populations an object belongs to in the present inventory of outer solar system objects. Quantitative analysis is underway.This work has been supported by the Keck Institute for Space Studies

  19. Trojan Tour and Rendezvous (TTR): A New Frontiers Mission to Conduct the First Detailed Reconnaissance of the Jupiter Trojan Asteroids

    NASA Astrophysics Data System (ADS)

    Bell, James F.; Olkin, Cathy; Castillo-Rogez, Julie

    2015-11-01

    Among the most potentially diagnostic but least explored populations of small bodies are the Jupiter Trojan asteroids, which orbit at ~5 AU in the L4 and L5 Lagrange points of Jupiter. The Trojans provide a unique perspective on solar system history, because their locations and physical, compositional, and mineralogic properties preserve evidence for important gravitational interactions among the giant planets. The locations and orbital properties of more than 6200 Jupiter Trojans are now known, but that is likely only a small fraction of a population of up to ~1e6 Trojans >1 km in size. The Trojans are hypothesized to be either former KBOs scattered into the inner solar system by early giant planet migration and then trapped in L4 and L5, or bodies formed near 5 AU in a more quiescent early solar system.Important Planetary Decadal Survey questions that can be addressed by studying the Trojans include: (a) How did the giant planets and their satellite systems accrete, and is there evidence that they migrated to new orbital positions? (b) What is the relationship between large and small KBOs? Is the small population derived by impact disruption of the large one? (c) What kinds of surface evolution, radiation chemistry, and surface-atmosphere interactions occur on distant icy primitive bodies? And (d) What are the sources of asteroid groups (Trojans and Centaurs) that remain to be explored by spacecraft?Here we describe the Trojan Tour and Rendezvous (TTR) New Frontiers mission concept, which is designed to answer these Decadal questions and to test hypotheses for early giant planet migration and solar system evolution. Via close flybys of many of these objects, and orbital characterization of at least one large Trojan, TTR will enable the initial up-close exploration of this population. Our primary mission goals are to characterize the overall surface geology, geochemistry and mineralogy of these worlds; to characterize their internal structure and dynamical

  20. The resonant structure of Jupiter's Trojan asteroids - I. Long-term stability and diffusion

    NASA Astrophysics Data System (ADS)

    Robutel, P.; Gabern, F.

    2006-11-01

    We study the global dynamics of the jovian Trojan asteroids by means of the frequency map analysis. We find and classify the main resonant structures that serve as skeleton of the phase space near the Lagrangian points. These resonances organize and control the long-term dynamics of the Trojans. Besides the secondary and secular resonances, that have already been found in other asteroid sets in mean motion resonance (e.g. main belt, Kuiper belt), we identify a new type of resonance that involves secular frequencies and the frequency of the great inequality, but not the libration frequency. Moreover, this new family of resonances plays an important role in the slow transport mechanism that drives Trojans from the inner stable region to eventual ejections. Finally, we relate this global view of the dynamics with the observed Trojans, identify the asteroids that are close to these resonances and study their long-term behaviour.

  1. Constraints on the Composition of Trojan Asteroid 624 Hektor

    NASA Technical Reports Server (NTRS)

    Cruikshank, Dale P.; DalleOre, Cristina M.; Roush, Ted L.; Geballe, Thomas R.; Owen, Tobias C.; deBergh, Catherine; Cash, Michael D.; Hartmann, William K.; DeVincenzi, Donald L. (Technical Monitor)

    2001-01-01

    We present a composite spectrum of Trojan asteroid 624 Hektor, 0.3-3.6 microns, which shows that there is no discernible 3-micron absorption band. Such a band would indicate the presence of OH or H2O- bearing silicate minerals, or macromolecular carbon-rich organic material of the kind seen on the low-albedo hemisphere of Saturn's satellite Iapetus (Owen et al. 2000). The absence of spectral structure is itself indicative of the absence of the nitrogen-rich tholins (which show a distinctive absorption band attributed to N-H). The successful models in this study all incorporate the mineral pyroxene (Mg, Fe SiO3, the composition of hypersthene), which matches the red color of Hektor. Pyroxene is a mafic mineral common in terrestrial and lunar lavas, and is also seen in Main Belt asteroid spectra. An upper limit to the amount of crystalline H20 ice (30-micron grains) in the surface layer of Hektor is 3 weight percent. The upper limit for serpentine, as a representative of hydrous silicates, is much less stringent, at 40 percent, based on the shape of the spectral region around 3 gm. Thus, the spectrum at 3 gm does not preclude the presence of a few weight percent of volatile material in the surface layer of Hektor. All of the models we calculated require elemental carbon to achieve the low geometric albedo that matches Hektor. This carbon could be of organic or inorganic origin. By analogy, other D-type asteroids could achieve their red color, low albedo, and apparent absence of phyllosilicates, from compositions similar to the models presented here.

  2. The Trojan Asteroids as Bases to Monitor other Asteroids Potentially Dangerous for Earth

    NASA Astrophysics Data System (ADS)

    Maccone, C.; Bussolino, L.

    The Lagrangian points L4 and L5 of the Sun-Jupiter system and the Lagrangian point L5 of the Sun-Mars system are considered for the following two types of missions to monitor asteroid hazards to Earth: (1) Missions going from the Earth to either of the Jupiter Trojans at L4 and L5 by virtue of a Hohmann transfer requiring about 2.5 years of flight. Once there, a reconnaisance mission could determine which one of the Trojans is more suitable to host an optical telescope to detect the NEOs, to be launched in a subsequent mission. Alternatively, the Jupiter Trojans could be used to host a permanent space base for missiles capable of deflecting the trajectory of dangerous NEOs when these are so far away from the Sun that their Sun-centric speed is very low. The deflecting missile performance would therefore be fully optimised, increasing the chance of success of a dangerous NEO's deflection mission. (2) Missions with the same goals as above, but departing from Mars rather than the Earth. Of course,this set of missions belongs to the far future, when one or more permanent human bases will have been established on Mars, and the relevant launch facilities could be used. However, the basic advantage of such missions with respect to those described at (1) will be the shorter flight time and smaller v that we compute in this paper.

  3. The orbit of 2010 TK7: possible regions of stability for other Earth Trojan asteroids

    NASA Astrophysics Data System (ADS)

    Dvorak, R.; Lhotka, C.; Zhou, L.

    2012-05-01

    The first Earth Trojan has been observed and found to be on an interesting orbit close to the Lagrange point L4. In the present study, we therefore perform a detailed investigation of the stability of its orbit and moreover extend the study to give an idea of the probability of finding additional Earth Trojans. Our results are derived using three different approaches. In the first, we derive an analytical mapping in the spatial elliptic restricted three-body problem to find the phase space structure of the dynamical problem. We then explore the stability of the asteroid in the context of the phase space geometry, including the indirect influence of the additional planets of our Solar system. In the second approach, we use precise numerical methods to integrate the orbit forward and backward in time in different dynamical models. On the basis of a set of 400 clone orbits, we derive the probability of capture and escape of the Earth Trojan asteroid 2010 TK7. To this end, in the third approach we perform an extensive numerical investigation of the stability region of the Earth's Lagrangian points. We present a detailed parameter study of possible stable tadpole and horseshoe orbits of additional Earth Trojans, i.e. with respect to the semi-major axes and inclinations of thousands of fictitious Trojans. All three approaches lead to the conclusion that the Earth Trojan asteroid 2010 TK7 finds itself in an unstable region on the edge of a stable zone; additional Earth Trojan asteroids may be found in this regime of stability.

  4. Asteroid Systems: Binaries, Triples, and Pairs

    NASA Astrophysics Data System (ADS)

    Margot, J.-L.; Pravec, P.; Taylor, P.; Carry, B.; Jacobson, S.

    In the past decade, the number of known binary near-Earth asteroids has more than quadrupled and the number of known large main-belt asteroids with satellites has doubled. Half a dozen triple asteroids have been discovered, and the previously unrecognized populations of asteroid pairs and small main-belt binaries have been identified. The current observational evidence confirms that small (≲20 km) binaries form by rotational fission and establishes that the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect powers the spin-up process. A unifying paradigm based on rotational fission and post-fission dynamics can explain the formation of small binaries, triples, and pairs. Large (>~20 km) binaries with small satellites are most likely created during large collisions.

  5. Orbital clustering of martian Trojans: An asteroid family in the inner Solar System?

    NASA Astrophysics Data System (ADS)

    Christou, Apostolos A.

    2013-05-01

    We report on the discovery of new martian Trojans within the Minor Planet Center list of asteroids. Their orbital evolution over 108 yr shows characteristic signatures of dynamical longevity (Scholl, H., Marzari, F., Tricarico, P. [2005]. Icarus 175, 397-408) while their average orbits resemble that of the largest known martian Trojan, 5261 Eureka. The group forms a cluster within the region where the most stable Trojans should reside. Based on a combinatorial analysis and a comparison with the jovian Trojan population, we argue that both this feature and the apparent paucity of km-sized martian Trojans (Trilling, D.E., Spahr, T.B., Rivkin, A.S., Hergenrother, C.W., Kortenkamp, S.J. [2006]. ID 2006A-0251) as compared to expectations from earlier work (Tabachnik, S., Evans, N.W. [1999]. Astrophys. J. 517, L63-L66) is not due to observational bias but instead a natural end result of the collisional comminution (Jutzi, M., Michel, P., Benz, W., Richardson, D.C. [2010]. Icarus 207, 54-65) or, alternatively, the rotational fission (Pravec, P. et al. [2010]. Nature 466, 1085-1088) of a progenitor L5 Trojan of Mars. Under the collisional scenario in particular, the new martian Trojans are dynamically young, in agreement with our age estimate of this "cluster" of <2 Gyr based on the earlier work of Scholl et al. (Scholl, H., Marzari, F., Tricarico, P. [2005]. Icarus 175, 397-408). This work highlights the Trojan regions of the terrestrial planets as natural laboratories to study processes important for small body evolution in the Solar System and provides the first direct evidence for an orbital cluster of asteroids close to the Earth.

  6. Are large Trojan asteroids salty? An observational, theoretical, and experimental study

    NASA Astrophysics Data System (ADS)

    Yang, Bin; Lucey, Paul; Glotch, Timothy

    2013-03-01

    With a total mass similar to the main asteroid belt, the jovian Trojan asteroids are a major feature in the Solar System. Based upon the thermal infrared spectra of the largest Trojans obtained with the Spitzer space telescope, Emery et al. (Emery, J.P., Cruikshank, D.P., van Cleve, J. [2006]. Icarus 182, 496) suggested that the surfaces of these Trojans may consist of fine-grained silicates suspended in a transparent matrix. To explore the transparent matrix hypothesis, we adopted a modified radiative transfer model to fit the Trojan spectra simultaneously both in the near and the thermal infrared regions. Our model shows that the Trojan spectra over a wide wavelength range can be consistently explained by fine grained silicates (1-5 wt.%) and highly absorbing material (e.g. carbon or iron, 2-10 wt.%) suspended in a transparent matrix. The matrix is consistent with a deposit of salt on the surfaces of the large Trojans. However, this consistency is not an actual detection of salt and other alternatives may still be possible. We suggest that early in the Solar System history, short-lived radionuclides heated ice-rich Trojans and caused melting, internal circulation of water and dissolution of soluble materials. Briny water volcanism were facilitated by internal volatiles and a possibly global sill of frozen brine was formed beneath the cold primitive crust. The frozen brine layer was likely to be evacuated by impact erosions and evaporation of the exposed brines eventually left a lag deposit of salt. Over the Solar System’s history, fine dust from comets or impacts contaminated and colored these salty surfaces of the Trojans to produce the spectral properties observed today.

  7. Constraining the shape distribution and binary fractions of asteroids observed by NEOWISE

    NASA Astrophysics Data System (ADS)

    Sonnett, Sarah M.; Mainzer, Amy; Grav, Tommy; Masiero, Joseph; Bauer, James; Vernazza, Pierre; Ries, Judit Gyorgyey; Kramer, Emily

    2015-11-01

    Knowing the shape distribution of an asteroid population gives clues to its collisional and dynamical history. Constraining light curve amplitudes (brightness variations) offers a first-order approximation to the shape distribution, provided all asteroids in the distribution were subject to the same observing biases. Asteroids observed by the NEOWISE space mission at roughly the same heliocentric distances have essentially the same observing biases and can therefore be inter-compared. We used the archival NEOWISE photometry of a statistically significant sample of Jovian Trojans, Hildas, and Main belt asteroids to compare the amplitude (and by proxy, shape) distributions of L4 vs. L5 Trojans, Trojans vs. Hildas of the same size range, and several subpopulations of Main belt asteroids.For asteroids with near-fluid rubble pile structures, very large light curve amplitudes can only be explained by close or contact binary systems, offering the potential to catalog and characterize binaries within a population and gleaning more information on its dynamical evolution. Because the structure of most asteroids is not known to a high confidence level, objects with very high light curve amplitudes can only be considered candidate binaries. In Sonnett et al. (2015), we identified several binary candidates in the Jovian Trojan and Hilda populations. We have since been conducting a follow-up campaign to obtain densely sampled light curves of the binary candidates to allow detailed shape and binary modeling, helping identify true binaries. Here, we present preliminary results from the follow-up campaign, including rotation properties.This research was carried out at the Jet Propulsion Laboratory (JPL), California Institute of Technology (CalTech) under a contract with the National Aeronautics and Space Administration (NASA) and was supported by the NASA Postdoctoral Program at JPL. We make use of data products from the Wide-field Infrared Survey Explorer, which is a joint project

  8. Rotation Frequencies of Small Jovian Trojan Asteroids: An Excess of Slow Rotators

    NASA Astrophysics Data System (ADS)

    French, Linda M.; Stephens, Robert D.; James, David J.; Coley, Daniel; Connour, Kyle

    2015-11-01

    Several lines of evidence support a common origin for, and possible hereditary link between, cometary nuclei and jovian Trojan asteroids. Due to their distance and low albedos, few comet-sized Trojans have been studied. We discuss the rotation properties of Jovian Trojan asteroids less than 30 km in diameter. Approximately half the 131 objects discussed here were studied using densely sampled lightcurves (French et al. 2015a, b); Stephens et al. 2015), and the other half were sparse lightcurves obtained by the Palomar Transient Factory (PTF; Waszcazk et al. 2015).A significant fraction (~40%) of the objects in the ground-based sample rotate slowly (P > 24h), with measured periods as long as 375 h (Warner and Stephens 2011). The PTF data show a similar excess of slow rotators. Only 5 objects in the combined data set have rotation periods of less than six hours. Three of these fast rotators were contained in the data set of French et al. these three had a geometric mean rotation period of 5.29 hours. A prolate spheroid held together by gravity rotating with this period would have a critical density of 0.43 gm/cm3, a density similar to that of comets (Lamy et al. 2004).Harris et al. (2012) and Warner et al. (2011) have explored the possible effects on asteroid rotational statistics with the results from wide-field surveys. We will examine Trojan rotation statistics with and without the results from the PTF.

  9. Where did the Trojan asteroids form? Constraints from composition and size distributions

    NASA Astrophysics Data System (ADS)

    Emery, Joshua; Bell, Jim; Trilling, David; Patience, Jennifer; Brown, Mike

    2014-08-01

    We propose to make near-infrared (0.8 - 2.5 μm) spectral observations of 15 small to medium sized (<100 km) Jovian Trojan asteroids. These objects are part of a substantial population of primitive bodies trapped in Jupiter's stable Lagrange regions. Because they may have become trapped in these orbits at the end of the initial phase of planetary formation and subsequent migration, the physical properties of Trojans provide unique perspectives on chemical and dynamical processes that shaped the Solar System. Indeed, in recognition of their importance, the Trojans are one of only five allowable target destinations for NASA's next New Frontiers mission. Previous observations have identified two spectral classes, suggesting that the Trojans are comprised of two distinct compositional groups, perhaps representing distinct outer Solar System reservoirs for their formation. These new proposed observations will: (a) Enable a search for minor absorptions due to ices, organics, and/or silicates in the smallest Trojans yet observed, near and below the size regime thought to represent the largest collisional fragments from impacts within the Trojan clouds; and (b) Test whether the two spectral groups previously identified have different cumulative size distributions, which would suggest different internal strengths and support the hypothesis of distinct compositions and origins.

  10. A NEAR-INFRARED SEARCH FOR SILICATES IN JOVIAN TROJAN ASTEROIDS

    SciTech Connect

    Yang Bin; Jewitt, David E-mail: jewitt@ucla.edu

    2011-03-15

    We obtained near-infrared (NIR; 0.8-2.5 {mu}m) spectra of seven Jovian Trojan asteroids that have been formerly reported to show silicate-like absorption features near 1 {mu}m. Our sample includes the Trojan (1172) Aneas, which is one of the three Trojans known to possess a comet-like 10 {mu}m emission feature, indicative of fine-grained silicates. Our observations show that all seven Trojans appear featureless in high signal-to-noise ratio spectra. The simultaneous absence of the 1 {mu}m band and the presence of the 10 {mu}m emission can be understood if the silicates on (1172) Aneas are iron-poor. In addition, we present NIR observations of five optically gray Trojans, including three objects from the collisionally produced Eurybates family. The five gray Trojans appear featureless in the NIR with no diagnostic absorption features. The NIR spectrum of Eurybates can be best fitted with the spectrum of a CM2 carbonaceous chondrite, which hints that the C-type Eurybates family members may have experienced aqueous alteration.

  11. Investigating Trojan Asteroids at the L4/L5 Sun-Earth Lagrange Points

    NASA Technical Reports Server (NTRS)

    John, K. K.; Graham, L. D.; Abell, P. A.

    2015-01-01

    Investigations of Earth's Trojan asteroids will have benefits for science, exploration, and resource utilization. By sending a small spacecraft to the Sun-Earth L4 or L5 Lagrange points to investigate near-Earth objects, Earth's Trojan population can be better understood. This could lead to future missions for larger precursor spacecraft as well as human missions. The presence of objects in the Sun-Earth L4 and L5 Lagrange points has long been suspected, and in 2010 NASA's Wide-field Infrared Survey Explorer (WISE) detected a 300 m object. To investigate these Earth Trojan asteroid objects, it is both essential and feasible to send spacecraft to these regions. By exploring a wide field area, a small spacecraft equipped with an IR camera could hunt for Trojan asteroids and other Earth co-orbiting objects at the L4 or L5 Lagrange points in the near-term. By surveying the region, a zeroth-order approximation of the number of objects could be obtained with some rough constraints on their diameters, which may lead to the identification of potential candidates for further study. This would serve as a precursor for additional future robotic and human exploration targets. Depending on the inclination of these potential objects, they could be used as proving areas for future missions in the sense that the delta-V's to get to these targets are relatively low as compared to other rendezvous missions. They can serve as platforms for extended operations in deep space while interacting with a natural object in microgravity. Theoretically, such low inclination Earth Trojan asteroids exist. By sending a spacecraft to L4 or L5, these likely and potentially accessible targets could be identified.

  12. Binaries and triples among asteroid pairs

    NASA Astrophysics Data System (ADS)

    Pravec, Petr; Scheirich, Peter; Kušnirák, Peter; Hornoch, Kamil; Galád, Adrián

    2015-08-01

    Despite major achievements obtained during the past two decades, our knowledge of the population and properties of small binary and multiple asteroid systems is still far from advanced. There is a numerous indirect evidence for that most small asteroid systems were formed by rotational fission of cohesionless parent asteroids that were spun up to the critical frequency presumably by YORP, but details of the process are lacking. Furthermore, as we proceed with observations of more and more binary and paired asteroids, we reveal new facts that substantially refine and sometimes change our understanding of the asteroid systems. One significant new finding we have recently obtained is that primaries of many asteroid pairs are actually binary or triple systems. The first such case found is (3749) Balam (Vokrouhlický, ApJL 706, L37, 2009). We have found 9 more binary systems among asteroid pairs within our ongoing NEOSource photometric project since October 2012. They are (6369) 1983 UC, (8306) Shoko, (9783) Tensho-kan, (10123) Fideoja, (21436) Chaoyichi, (43008) 1999 UD31, (44620) 1999 RS43, (46829) 1998 OS14 and (80218) 1999 VO123. We will review their characteristics. These paired binaries as we call them are mostly similar to binaries in the general ("background") population (of unpaired asteroids), but there are a few trends. The paired binaries tend to have larger secondaries with D_2/D_1 = 0.3 to 0.5 and they also tend to be wider systems with 8 of the 10 having orbital periods between 30 and 81 hours, than average among binaries in the general population. There may be also a larger fraction of triples; (3749) Balam is a confirmed triple, having a larger close and a smaller distant satellite, and (8306) Shoko and (10123) Fideoja are suspect triples as they show additional rotational lightcurve components with periods of 61 and 38.8 h that differ from the orbital period of 36.2 and 56.5 h, respectively. The unbound secondaries tend to be of the same size or

  13. Paucity of Tagish Lake-like parent bodies in the Asteroid Belt and among Jupiter Trojans

    NASA Astrophysics Data System (ADS)

    Vernazza, P.; Fulvio, D.; Brunetto, R.; Emery, J. P.; Dukes, C. A.; Cipriani, F.; Witasse, O.; Schaible, M. J.; Zanda, B.; Strazzulla, G.; Baragiola, R. A.

    2013-07-01

    We present new results for ion irradiation experiments performed on fragments of the Tagish Lake (TL) meteorite. These experiments were focused on (a) quantifying the effect of the solar wind on spectral reflectance and (b) identifying the parent bodies of TL within the Asteroid Belt and or Jupiter Trojans. In the visible and near-infrared, we observe a flattening and brightening of the reflectance with progressive irradiation; in the mid-infrared, we observe a small shift towards longer wavelengths of the main emission feature at 10 μm consistent with what is observed in silicates, likely caused by amorphization. We evaluated possible parent bodies for Tagish Lake by comparing its total reflectance in the visible and spectral changes in the 0.4-25 μm range with available measurements for main belt asteroids and Jupiter Trojans (asteroid data includes measurements from the WISE, SMASS and Spitzer surveys as well as IRTF observations). The low reflectance of TL compared to asteroid albedos shows that TL-like bodies are very rare among Jupiter Trojans (<0.02% of the total population) and that they exist in a very small proportion (<4.5% of the total population) among main belt asteroids, where only one asteroid, 368 Haidea, was found to match both TL's spectrum and reflectance. Additionally, TL-like bodies would be preferentially located in the outer Asteroid Belt (2.85-3.3 AU) further away from the Sun than the average current location of most Ch- and Cgh-types, these objects being the likely parent bodies of CM-type chondritic meteorites. It thus appears that the location of both meteorite groups (TL and CM) must be different, with TL having formed further away from the Sun than CMs. We find that there are by far more parent bodies of CM than TL-like meteorites, which still remains to be understood.

  14. Photometric Survey for Asynchronous Binary Asteroids

    NASA Astrophysics Data System (ADS)

    Pravec, P.

    2005-05-01

    Asynchronous binary asteroids have been found to be abundant among fast- spinning near-Earth asteroids (NEAs) smaller than 2 km in diameter; Pravec et al. (2005, Icarus, submitted) derived that 15 +/- 4 % of NEAs in the size range 0.3 to 2 km are binary with the secondary-to-primary mean diameter ratio >=0.18. The early re-sults from the surveys of the Vesta family and the Hungaria group (Ryan et al., 2004, Planet. Space Sci. 42, 1093; 2004, Bull. Amer. Astron. Society 36, 1181; Warner et al., 2005, IAU Circ. 8511) suggest that the popula-tion extends beyond the region of terrestrial planets, but with characteristics shifted to larger sizes and longer periods; the four known binaries in the Vesta family/Hungaria group are 3 to 6 km large and they have primary rotation periods in a range of 3 to ~4 h, i.e., on the tail of the distribution of primary rotation periods of NEAs. The comparison suggests that formation and evolution mechanisms of asynchronous NEA and main-belt binaries may be similar and are related to their fast spins and rubble-pile structure. None of the current theories of their formation of evolution, however, explains the observed properties of both NEA and main- belt asynchronous bina-ries in full. We have established a collaborative observational program, called "Photometric Survey for Asynchro-nous Binary Asteroids" to discover and describe asynchronous binaries over a range of heliocentric distances from NEAs through Mars-crossers to inner main-belt asteroids. One new binary Amor asteroid, 2005 AB has been found during the first few months of the survey operation (Reddy et al., 2005, IAU Circ. 8483), and we have obtained follow-up data for two other binary systems. I outline the motivations, the technique, and the strategy of the Survey.

  15. Photometric constraints on binary asteroid dynamics

    NASA Astrophysics Data System (ADS)

    Scheirich, Peter

    2015-08-01

    To date, about 50 binary NEAs, 20 Mars-crossing and 80 small MB asteroids are known. We observe also a population of about 200 unbound asteroid systems (asteroid pairs). I will review the photometric observational data we have for the best observed cases and compare them with theories of binary and paired asteroids evolution.The observed characteristics of asteroid systems suggest their formation by rotational fission of parent rubble-pile asteroids after being spun up by the YORP effect. The angular momentum content of binary asteroids is close to critical. The orientations of satellite orbits of observed binary systems are non-random; the orbital poles concentrate near the obliquities of 0 and 180 degrees, i.e., near the YORP asymptotic states.Recently, a significant excess of retrograde satellite orbits was detected, which is not yet explained characteristic.An evolution of binary system depend heavily on the BYORP effect. If BYORP is contractive, the primary and secondary could end in a tidal-BYORP equilibrium. Observations of mutual events between binary components in at least four apparitions are needed for BYORP to be revealed by detecting a quadratic drift in mean anomaly of the satellite. I will show the observational evidence of single-synchronous binary asteroid with tidally locked satellite (175706 1996 FG3), i.e, with the quadratic drift equal to zero, and binary asteroid with contracting orbit (88710 2001 SL9), with positive value of the quadratic drift (the solution for the quadratic drift is ambiguous so far, with possible values of 5 and 8 deg/yr2).The spin configuration of the satellite play a crucial role in the evolution of the system under the influence of the BYORP effect. I will show that the rotational lightcurves of the satellites show that most of them have small libration amplitudes (up to 20 deg.), with a few interesting exceptions.Acknowledgements: This work has been supported by the Grant Agency of the Czech Republic, Grant P209

  16. Collisional Histories of Comets and Trojan Asteroids: Insights from Forsterite and Enstatite Impact Studies

    NASA Technical Reports Server (NTRS)

    Lederer. S. M.; Jensen, E. A.; Wooden, D. H.; Lindsay, S. S.; Smith, D. C.; Cintala, M. J.; Nakamura-Messenger, K.; Keller, L. P.

    2012-01-01

    Impacts into forsterite and orthoenstatite at speeds typically encountered by comets demonstrate that shock imparted by collisions is detectable in the infrared signatures of their dust. The spectral signatures can be traced to physical alterations in their crystalline structures, as observed in TEM imaging and modeled using a dipole approximation. These results yield tantalizing insights into the collisional history of our solar system, as well as the history of individual comets and Trojan asteroids.

  17. NEAR-INFRARED SPECTROSCOPY OF TROJAN ASTEROIDS: EVIDENCE FOR TWO COMPOSITIONAL GROUPS

    SciTech Connect

    Emery, J. P.; Burr, D. M.; Cruikshank, D. P.

    2011-01-15

    The Trojan asteroids, a very substantial population of primitive bodies trapped in Jupiter's stable Lagrange regions, remain quite poorly understood. Because they occupy these orbits, the physical properties of Trojans provide a unique perspective on the chemical and dynamical processes that shaped the Solar System. The current study was therefore undertaken to investigate surface compositions of these objects. We present 66 new near-infrared (NIR; 0.7-2.5 {mu}m) spectra of 58 Trojan asteroids, including members of both the leading and trailing swarms. We also include in the analysis previously published NIR spectra of 13 Trojans (3 of which overlap with the new sample). This data set permits not only a direct search for compositional signatures, but also a search for patterns that may reveal clues to the origin of the Trojans. We do not report any confirmed absorption features in the new spectra. Analysis of the spectral slopes, however, reveals an interesting bimodality among the NIR data. The two spectral groups identified appear to be equally abundant in the leading and trailing swarms. The spectral groups are not a result of family membership; they occur in the background, non-family population. The average albedos of the two groups are the same within uncertainties (0.051 {+-} 0.016 and 0.055 {+-} 0.016). No correlations between spectral slope and any other physical or orbital parameter are detected, with the exception of a possible weak correlation with inclination among the less-red spectral group. The NIR spectral groups are consistent with a similar bimodality previously suggested among visible colors and spectra. Synthesizing the present results with previously published properties of Trojans, we conclude that the two spectral groups represent objects with different intrinsic compositions. We further suggest that whereas the less-red group originated near Jupiter or in the main asteroid belt, the redder spectral group originated farther out in the Solar

  18. Near-infrared Spectroscopy of Trojan Asteroids: Evidence for Two Compositional Groups

    NASA Astrophysics Data System (ADS)

    Emery, J. P.; Burr, D. M.; Cruikshank, D. P.

    2011-01-01

    The Trojan asteroids, a very substantial population of primitive bodies trapped in Jupiter's stable Lagrange regions, remain quite poorly understood. Because they occupy these orbits, the physical properties of Trojans provide a unique perspective on the chemical and dynamical processes that shaped the Solar System. The current study was therefore undertaken to investigate surface compositions of these objects. We present 66 new near-infrared (NIR; 0.7-2.5 μm) spectra of 58 Trojan asteroids, including members of both the leading and trailing swarms. We also include in the analysis previously published NIR spectra of 13 Trojans (3 of which overlap with the new sample). This data set permits not only a direct search for compositional signatures, but also a search for patterns that may reveal clues to the origin of the Trojans. We do not report any confirmed absorption features in the new spectra. Analysis of the spectral slopes, however, reveals an interesting bimodality among the NIR data. The two spectral groups identified appear to be equally abundant in the leading and trailing swarms. The spectral groups are not a result of family membership; they occur in the background, non-family population. The average albedos of the two groups are the same within uncertainties (0.051 ± 0.016 and 0.055 ± 0.016). No correlations between spectral slope and any other physical or orbital parameter are detected, with the exception of a possible weak correlation with inclination among the less-red spectral group. The NIR spectral groups are consistent with a similar bimodality previously suggested among visible colors and spectra. Synthesizing the present results with previously published properties of Trojans, we conclude that the two spectral groups represent objects with different intrinsic compositions. We further suggest that whereas the less-red group originated near Jupiter or in the main asteroid belt, the redder spectral group originated farther out in the Solar System

  19. BINARY YORP EFFECT AND EVOLUTION OF BINARY ASTEROIDS

    SciTech Connect

    Steinberg, Elad; Sari, Re'em

    2011-02-15

    The rotation states of kilometer-sized near-Earth asteroids are known to be affected by the Yarkevsky O'Keefe-Radzievskii-Paddack (YORP) effect. In a related effect, binary YORP (BYORP), the orbital properties of a binary asteroid evolve under a radiation effect mostly acting on a tidally locked secondary. The BYORP effect can alter the orbital elements over {approx}10{sup 4}-10{sup 5} years for a D{sub p} = 2 km primary with a D{sub s} = 0.4 km secondary at 1 AU. It can either separate the binary components or cause them to collide. In this paper, we devise a simple approach to calculate the YORP effect on asteroids and the BYORP effect on binaries including J{sub 2} effects due to primary oblateness and the Sun. We apply this to asteroids with known shapes as well as a set of randomly generated bodies with various degrees of smoothness. We find a strong correlation between the strengths of an asteroid's YORP and BYORP effects. Therefore, statistical knowledge of one could be used to estimate the effect of the other. We show that the action of BYORP preferentially shrinks rather than expands the binary orbit and that YORP preferentially slows down asteroids. This conclusion holds for the two extremes of thermal conductivities studied in this work and the assumption that the asteroid reaches a stable point, but may break down for moderate thermal conductivity. The YORP and BYORP effects are shown to be smaller than could be naively expected due to near cancellation of the effects at small scales. Taking this near cancellation into account, a simple order-of-magnitude estimate of the YORP and BYORP effects as a function of the sizes and smoothness of the bodies is calculated. Finally, we provide a simple proof showing that there is no secular effect due to absorption of radiation in BYORP.

  20. SEARCHING FOR TROJAN ASTEROIDS IN THE HD 209458 SYSTEM: SPACE-BASED MOST PHOTOMETRY AND DYNAMICAL MODELING

    SciTech Connect

    Moldovan, Reka; Matthews, Jaymie M.; Gladman, Brett; Bottke, William F.; Vokrouhlicky, David

    2010-06-10

    We have searched Microvariability and Oscillations of Stars (MOST) satellite photometry obtained in 2004, 2005, and 2007 of the solar-type star HD 209458 for Trojan asteroid swarms dynamically coupled with the system's transiting 'hot Jupiter' HD 209458b. Observations of the presence and nature of asteroids around other stars would provide unique constraints on migration models of exoplanetary systems. Our results set an upper limit on the optical depth of Trojans in the HD 209458 system that can be used to guide current and future searches of similar systems by upcoming missions. Using cross-correlation methods with artificial signals implanted in the data, we find that our detection limit corresponds to a relative Trojan transit depth of 1 x10{sup -4}, equivalent to {approx}1 lunar mass of asteroids, assuming power-law Trojan size distributions similar to Jupiter's Trojans in our solar system. We confirm with dynamical interpretations that some asteroids could have migrated inward with the planet to its current orbit at 0.045 AU, and that the Yarkovsky effect is ineffective at eliminating objects of >1 m in size. However, using numerical models of collisional evolution we find that, due to high relative speeds in this confined Trojan environment, collisions destroy the vast majority of the asteroids in <10 Myr. Our modeling indicates that the best candidates to search for exoTrojan swarms in 1:1 mean resonance orbits with 'hot Jupiters' are young systems (ages of about 1 Myr or less). Years of Kepler satellite monitoring of such a system could detect an asteroid swarm with a predicted transit depth of 3 x 10{sup -7}.

  1. Forming the wide asynchronous binary asteroid population

    NASA Astrophysics Data System (ADS)

    Jacobson, S.; Scheeres, D.; McMahon, J.

    2014-07-01

    We propose and analyze a new mechanism for the formation of the wide asynchronous binary population. These binary asteroids have wide semi-major axes relative to most near-Earth-asteroid and main-belt-asteroid systems as shown in the attached table. Confirmed members have rapidly rotating primaries and satellites that are not tidally locked. Previously suggested formation mechanisms from impact ejecta, from planetary flybys, and directly from rotational-fission events cannot satisfy all of the observations. The newly hypothesized mechanism works as follows: (1) these systems are formed from rotational fission, (2) their satellites are tidally locked, (3) their orbits are expanded by the binary Yarkovsky-O'Keefe-Radzievskii-Paddack (BYORP) effect, (4) their satellites desynchronize as a result of the adiabatic invariance between the libration of the secondary and the mutual orbit, and (5) the secondary avoids resynchronization because of the YORP effect. This seemingly complex chain of events is a natural pathway for binaries with satellites that have particular shapes, which define the BYORP effect torque that acts on the system. After detailing the theory, we analyze each of the wide-asynchronous-binary members and candidates to assess their most likely formation mechanism. Finally, we suggest possible future observations to check and constrain our hypothesis.

  2. Visible and near-infrared spectroscopic survey of Jupiter Trojan asteroids: investigation of dynamical families

    NASA Astrophysics Data System (ADS)

    Dotto, E.; Fornasier, S.; Barucci, M. A.; Boehnhardt, H.; Hainaut, O.; Marzari, F.; Licandro, J.; de Bergh, C.

    2004-11-01

    Trojan asteroids located in the Jupiter Lagrangian points L4 and L5 (60 degrees ahead and behind Jupiter) are widely believed to be primordial bodies since their orbits are stable over the age of the Solar System. They seem to have been formed in a region of the solar nebula rich in frozen volatiles and to have never suffered selective induction heating. They probably still contain ices in their interiors.Moreover the discovery of several dynamical families among Trojans suggests that they are at least as collisionally evolved as the main asteroid belt. Since 2002, we started an observational program on Jupiter Trojans at ESO-NTT, ESO-VLT and TNG. In particular we concentrated on members of dynamical families, as defined by Beauge and Roig (2001), and we observed also several background objects. We carry out visible and near-infrared spectroscopy and photometry in order to i) characterize the mineralogical composition of families, ii) give evidence of ongoing space weathering, and iii) confirm family membership. As expected, the spectra of the non-family members are more heterogeneous compared to the spectra of family members. The obtained results will be presented and discussed.

  3. Surface mineralogy of Trojan asteroids and extinct comets as a proxy for the outer Solar System

    NASA Astrophysics Data System (ADS)

    Houck, James R.; Cruikshank, Dale; Emery, Joshua

    2006-05-01

    We propose to use IRS to observe emission spectra a suite of Trojan asteroids and extinct Jupiter family comets (JFCs). The goals of this work are to determine their surface compositions and to gain information on their surface microstructures; both factors influence the spectra of these airless bodies in the thermal infrared region covered by IRS. Trojan asteroids and extinct JFCs are thought, on dynamical grounds, to have originated in the outer Solar System, beyond Jupiter. The small bodies that accreted in the outer Solar System carry compositional information of the contents of the solar nebula in the region where silicates, organics, and ices inherited from the interstellar medium were largely preserved because of the low temperature. Because all but a very few of the objects that presently remain in the distant Solar System (the Kuiper Belt Objects) are too small and faint for mid-IR spectroscopy, the study the Trojans and JFCs is essential to characterize the compositions of a class of object that is otherwise unobservable.

  4. Formation and Evolution of Binary Asteroids

    NASA Astrophysics Data System (ADS)

    Walsh, K. J.; Jacobson, S. A.

    Satellites of asteroids have been discovered in nearly every known small-body population, and a remarkable aspect of the known satellites is the diversity of their properties. They tell a story of vast differences in formation and evolution mechanisms that act as a function of size, distance from the Sun, and the properties of their nebular environment at the beginning of solar system history and their dynamical environment over the next 4.5 G.y. The mere existence of these systems provides a laboratory to study numerous types of physical processes acting on asteroids, and their dynamics provide a valuable probe of their physical properties otherwise possible only with spacecraft. Advances in understanding the formation and evolution of binary systems have been assisted by (1) the growing catalog of known systems, increasing from 33 to ~250 between the Merline et al. (2002) chapter in Asteroids III and now; (2) the detailed study and long-term monitoring of individual systems such as 1999 KW4 and 1996 FG3, (3) the discovery of new binary system morphologies and triple systems, (4) and the discovery of unbound systems that appear to be end-states of binary dynamical evolutionary paths. Specifically for small bodies (diameter smaller than 10 km), these observations and discoveries have motivated theoretical work finding that thermal forces can efficiently drive the rotational disruption of small asteroids. Long-term monitoring has allowed studies to constrain the system's dynamical evolution by the combination of tides, thermal forces, and rigid-body physics. The outliers and split pairs have pushed the theoretical work to explore a wide range of evolutionary end-states.

  5. Some (Apparently) Very Wide Binary Asteroids

    NASA Astrophysics Data System (ADS)

    Warner, Brian D.; Harris, Alan W.; Stephens, Robert D.

    2016-10-01

    We present lightcurves for some of the approximately one dozen asteroids that appear to be very widely-separated binaries. Jacobsen et al. (2014, ApJ 780) attribute their formation to a somewhat complex series of events involving BYORP.The lightcurves consist of two components: Period 1 (P1) is very long, P1 = 50-600 h, with amplitudes of A1 = 0.23-1.0 mag. The second period and amplitudes are similar to the primaries of close binary systems, i.e., P2 = 2.2-3.6 h, A2 ~ 0.10 mag. Two candidates have secondary periods in the range of 5-7 hours. The most exceptional example is (19204) Joshuatree, which has values of P1 = 480 h, A1 = 0.25 mag and P2 = 21.25 h, A2 = 0.08 mag. Based on Jacobson et al. (2014, ApJ 780) and Pravec et al. (2016, Icarus 267), we suggest that P1 represents the primary (larger) body of the system and P2 represents the spin rate of the satellite.Supporting this supposition is that the large amplitude (A1) must be from the larger body, otherwise the dilution of amplitude would require the smaller body to be unreasonably elongate. The limiting size ratio for binaries is around 0.6 (see Pravec et al. 2010, Nature 466, Fig. 1), or a magnitude difference of about 1.0. For a secondary 1.0 mag fainter than the primary to produce a combined lightcurve amplitude of ~0.4 mag would require that the secondary undiluted amplitude to be several magnitudes (near-infinite elongation) and also a near equatorial aspect. This is not likely.Given the lack of mutual events, these can be considered to be only possible binaries. Since the orbital period is probably very long, it seems extremely unlikely that mutual events will ever be seen.The changing landscape of binary asteroid discoveries and theories calls for something beyond descriptive terms such as "suspicious", "possible", "likely", and "confirmed" in order to allow more accurate statistical studies. To this end, we are introducing a new "B" rating in the asteroid lightcurve database (Warner et al., 2009

  6. Binary Asteroids and Human Exploration Considerations

    NASA Technical Reports Server (NTRS)

    Abell, P. A.

    2013-01-01

    In 2009 the Augustine Commission identified near-Earth asteroids (NEAs) as high profile destinations for human exploration missions beyond the Earth-Moon system as part of the Flexible Path. Subsequently, the U.S. presidential administration directed NASA on April 15, 2010 to include NEAs as destinations for future human exploration with the goal of sending astronauts to a NEA in the mid to late 2020s. This directive became part of the official National Space Policy of the United States of America as of June 28, 2010. Current NASA plans to explore NEAs do not include binary systems. However, with a few in situ robotic precursor missions to binary NEAs, and increased confidence in human mission capabilities, the scientific and hazard mitigation benefits, along with the programmatic and operational benefits of a human venture beyond the Earth-Moon system, make a mission to a binary NEA using NASA's proposed exploration systems a compelling endeavor.

  7. Is 1220 Crocus a precessing, binary asteroid?

    NASA Technical Reports Server (NTRS)

    Binzel, R. P.

    1985-01-01

    Photoelectric data of the asteroid 1220 Crocus over a 13 night period in 1984 revealed the presence of two separate periods. The light curves were indicative of a precessing body, but not one in free precession due to motions induced by a collision. Closer examinations revealed periods of 30.7 and 7.9 hr with amplitudes of 0.87 and 0.15 mag, respectively. An analysis of the source of an external torque which could be causing a forced precession led to the hypothesis that 1220 Crocus has a satellite. Verification of the binary asteroid configuration will depend on more detailed light curves, the possible modulation of the shorter period by the longer, and possible use of the Space Telescope.

  8. Is 1220 Crocus a precessing, binary asteroid?

    NASA Astrophysics Data System (ADS)

    Binzel, R. P.

    1985-07-01

    Photoelectric data of the asteroid 1220 Crocus over a 13 night period in 1984 revealed the presence of two separate periods. The light curves were indicative of a precessing body, but not one in free precession due to motions induced by a collision. Closer examinations revealed periods of 30.7 and 7.9 hr with amplitudes of 0.87 and 0.15 mag, respectively. An analysis of the source of an external torque which could be causing a forced precession led to the hypothesis that 1220 Crocus has a satellite. Verification of the binary asteroid configuration will depend on more detailed light curves, the possible modulation of the shorter period by the longer, and possible use of the Space Telescope.

  9. Surface Experiments on a Jupiter Trojan Asteroid in the Solar Powered Sail Mission

    NASA Astrophysics Data System (ADS)

    Okada, Tatsuaki

    2016-04-01

    Introduction: A new mission to a Jupiter Trojan asteroid is under study us-ing a solar-powered sail (SPS), and a science lander is being investigated in the joint study between Japan and Europe [1]. We present here the key sci-entific objectives and the strawman payloads of science experiments on the asteroid. Science Objectives: Jupiter Trojan asteroids are located around the Sun-Jupiter Lagrange points (L4 or L5) and most of them are classified as D- or P-type in asteroid taxonomy, but their origin still remains unknown. A classi-cal (static) model of solar system evolution indicates that they were formed around the Jupiter region and survived until now as the outer end members of asteroids. A new (dynamical) model such as Nice model suggests that they were formed at the far end of the solar system and transferred inward due to dynamical migration of giant planets [2]. Therefore physical, miner-alogical, and isotopic studies of surface materials and volatile compounds could solve their origin, and then the solar system formation [3]. Strawman Payloads: The SPS orbiter will be able to carry a 100 kg class lander with 20 kg mission payloads. Just after landing of the lander, geolog-ical, mineralogical, and geophysical observations will be performed to char-acterize the site using a panoramic optical camera, an infrared hyperspectral imager, a magnetometer, and a thermal radiometer. The surface and subsur-face materials of the asteroid will be collected into a carousel by the bullet-type and the pneumatic drill type samplers, respectively. Samples in the carousel will be investigated by a visible and an infrared microscope, and transferred for performing high resolution mass spectrometry (HRMS). Mass resolution m/dm > 30,000 is expected to investigate isotopic ratios of D/H, 15N/14N, and 18O/16O, as well as molecules from organic matters. A set of strawman payloads are tentatively determined during the lander system study [4]. The constraints to select the strawman

  10. Evolution of Small Binary Asteroids with the Binary YORP Effect

    NASA Astrophysics Data System (ADS)

    Frouard, Julien

    2013-05-01

    Abstract (2,250 Maximum Characters): Small, Near-Earth binaries are believed to be created following the fission of an asteroid spun up by the YORP effect. It is then believed that the YORP effect acting on the secondary (Binary YORP) increases or decreases the binary mutual distance on 10^5 yr timescales. How long this mechanism can apply is not yet fully understood. We investigate the binary orbital and rotational dynamics by using non-averaged, direct numerical simulations, taking into account the relative motion of two ellipsoids (primary and secondary) and the solar perturbation. We add the YORP force and torque on the orbital and rotational motion of the secondary. As a check of our code we obtain a ~ 7.2 cm/yr drift in semi-major axis for 1999 KW4 beta, consistent with the values obtained with former analytical studies. The synchronous rotation of the secondary is required for the Binary YORP to be effective. We investigate the synchronous lock of the secondary in function of different parameters ; mutual distance, shape of the secondary, and heliocentric orbit. For example we show that the secondary of 1999 KW4 can be synchronous only up to 7 Rp (primary radius), where the resonance becomes completely chaotic even for very small eccentricities. We use Gaussian Random Spheres to obtain various secondary shapes, and check the evolution of the binaries with the Binary YORP effect.

  11. Electron Irradiation and Thermal Processing of Mixed-ices of Potential Relevance to Jupiter Trojan Asteroids

    NASA Astrophysics Data System (ADS)

    Mahjoub, Ahmed; Poston, Michael J.; Hand, Kevin P.; Brown, Michael E.; Hodyss, Robert; Blacksberg, Jordana; Eiler, John M.; Carlson, Robert W.; Ehlmann, Bethany L.; Choukroun, Mathieu

    2016-04-01

    In this work we explore the chemistry that occurs during the irradiation of ice mixtures on planetary surfaces, with the goal of linking the presence of specific chemical compounds to their formation locations in the solar system and subsequent processing by later migration inward. We focus on the outer solar system and the chemical differences for ice mixtures inside and outside the stability line for H2S. We perform a set of experiments to explore the hypothesis advanced by Wong & Brown that links the color bimodality in Jupiter's Trojans to the presence of H2S in the surface of their precursors. Non-thermal (10 keV electron irradiation) and thermally driven chemistry of CH3OH-NH3-H2O (“without H2S”) and H2S-CH3OH-NH3-H2O (“with H2S”) ices were examined. Mid-IR analyses of ice and mass spectrometry monitoring of the volatiles released during heating show a rich chemistry in both of the ice mixtures. The “with H2S” mixture experiment shows a rapid consumption of H2S molecules and production of OCS molecules after a few hours of irradiation. The heating of the irradiated “with H2S” mixture to temperatures above 120 K leads to the appearance of new infrared bands that we provisionally assign to SO2and CS. We show that radiolysis products are stable under the temperature and irradiation conditions of Jupiter Trojan asteroids. This makes them suitable target molecules for potential future missions as well as telescope observations with a high signal-to-noise ratio. We also suggest the consideration of sulfur chemistry in the theoretical modeling aimed at understanding the chemical composition of Trojans and KOBs.

  12. Exploration of Jovian Magnetosphere and Trojan Asteroids by a Solar Power Sail Mission

    NASA Astrophysics Data System (ADS)

    Sasaki, S.; Fujimoto, M.; Kasaba, Y.; Kawaguchi, J.; Kawakatsu, Y.; Mori, O.; Takashima, T.; Tsuda, Y.; Yano, H.; Jupiter Exploration Working Group

    2009-04-01

    Europa Jupiter System Mission (EJSM) is a proposed international mission to explore Jupiter, Jovian satellites and environment. EJSM consists of (1) The Jupiter Europa Orbiter (JEO) by NASA, (2) the Jupiter Ganymede Orbiter (JGO) by ESA, (3) the Jupiter Magnetospheric Orbiter (JMO) studied by JAXA. (4) The Europa lander is also studied by Roscosmos. Together with plasma instruments on board JEO and JGO, JMO will investigate the fast and huge rotating magnetosphere to clarify the energy procurement from Jovian rotation to the magnetosphere, to clarify the interaction between the solar wind the magnetosphere. JMO will clarify the characteristics of the strongest accelerator in the solar system. JMO will investigate the role of Io as a source of heavy ions in the magnetosphere. Proposed instruments on board JMO are magnetometers, low-energy plasma spectrometers, medium energy particle detectors, energetic particle detectors, electric field / plasma wave instruments, a dust detector, an ENA imager, and EUV spectrometer. JAXA is studying solar power sail for deep space explorations following the successful ion engine mission Hayabusa. This is not only solar sail (photon propulsion) but also include very efficient ion engines where electric power is produced solar panels within the sail. Currently we are studying a mission to Jupiter and one (or two) of Trojan asteroids, which are primitive bodies with information of the early solar system as well as raw solid materials of Jovian system. As the main spacecraft flies by Jupiter heading for an asteroid, it will deploy JMO spinner around Jupiter.

  13. Dumb-bell-shaped equilibrium figures for fiducial contact-binary asteroids and EKBOs

    NASA Astrophysics Data System (ADS)

    Descamps, Pascal

    2015-01-01

    In this work, we investigate the equilibrium figures of a dumb-bell-shaped sequence with which we are still not well acquainted. Studies have shown that these elongated and nonconvex figures may realistically replace the classic “Roche binary approximation” for modeling putative peanut-shaped or contact binary asteroids. The best-fit dumb-bell shapes, combined with the known rotational period of the objects, provide estimates of the bulk density of these objects. This new class of mathematical figures has been successfully tested on the observed light curves of three noteworthy small bodies: main-belt Asteroid 216 Kleopatra, Trojan Asteroid 624 Hektor and Edgeworth-Kuiper-belt object 2001 QG298. Using the direct observations of Kleopatra and Hektor obtained with high spatial resolution techniques and fitting the size of the dumb-bell-shaped solutions, we derived new physical characteristics in terms of equivalent radius, 62.5 ± 5 km and 92 ± 5 km, respectively, and bulk density, 4.4 ± 0.4 g cm-3 and 2.43 ± 0.35 g cm-3, respectively. In particular, the growing inadequacy of the radar shape model for interpreting any type of observations of Kleopatra (light curves, AO images, stellar occultations) in a satisfactory manner suggests that Kleopatra is more likely to be a dumb-bell-shaped object than a “dog-bone.”

  14. Binary-YORP Coefficients for Known Asteroid Shapes

    NASA Astrophysics Data System (ADS)

    McMahon, Jay W.; Scheeres, D. J.

    2012-10-01

    The binary YORP (bYORP) effect has been hypothesized to be a significant factor in the evolution of near-Earth binary asteroid systems (Cuk and Burns, Icarus, v.176, pp.418-431, 2005; McMahon and Scheeres, CMDA, v.106, pp.261-300, 2010). However, understanding of the coefficient values for realistic asteroid shapes is lacking due to the small number of shape models available for the generally smaller secondary asteroids. Until now, we have only calculated the coefficients based on the shape of 1999 KW4 Beta, although various studies by other authors have computed coefficients for artificially generated asteroids based on Gaussian Spheres and some shape models without self-shadowing (Steinberg and Sari, The Astronomical Journal, v.141, pp.55-64, 2011). We also scaled the 1999 KW4 Beta coefficients to other binary systems with no knowledge of the other systems' secondary shapes in order to make evolutionary predictions (McMahon and Scheeres, Icarus Vol. 209, pp 494-509, 2010). In this study, we compute the bYORP coefficient for a range of asteroid shapes, using these as a stand-in for actual secondaries. This allows us to circumvent the lack of information on binary asteroid secondaries and to develop a richer database of realistic coefficients. While this approach may miss some key features of binary secondaries, at the least it provides some statistics on the expected variability of the bYORP coefficient. We analyze all available asteroid shape models on the PDS-SBN, including radar-based shape models and models estimated from past spacecraft missions. The coefficients are computed with an updated algorithm that includes the effects of self-shadowing. We also present the coefficients for perturbed versions of the available shape models, which give effective error bars to the computed coefficients due to inexact shape models. Finally, we discuss the dynamical implications of the derived bYORP coefficients on binary asteroid evolution.

  15. Lifetime of binary asteroids versus gravitational encounters and collisions

    NASA Technical Reports Server (NTRS)

    Chauvineau, Bertrand; Farinella, Paolo; Mignard, F.

    1992-01-01

    We investigate the effect on the dynamics of a binary asteroid in the case of a near encounter with a third body. The dynamics of the binary is modeled as a two-body problem perturbed by an approaching body in the following ways: near encounters and collisions with a component of the system. In each case, the typical value of the two-body energy variation is estimated, and a random walk for the cumulative effect is assumed. Results are applied to some binary asteroid candidates. The main conclusion is that the collisional disruption is the dominant effect, giving lifetimes comparable to or larger than the age of the solar system.

  16. Observation of asteroids with GRAVITY - Physical characterization of binary systems

    NASA Astrophysics Data System (ADS)

    Matter, A.; Delbo, M.; Carry, B.; Tanga, P.

    2014-12-01

    Density and internal structures are among the most important characteristics of asteroids, yet these properties are also some of the least known. For distant asteroids (in the Main Belt and beyond) these properties were up to now accessible only for the largest (>100 km in size) asteroids. Going to smaller and fainter asteroids can revolutionize our understanding because we will be sampling a new regime in physical properties. Here we discuss how ground-based optical interferometry with the GRAVITY instrument can be used to observe the motion of asteroid satellites to determine the mass of small binary systems. Following the expected sensitivity performances in K-band of GRAVITY, we present a sample of binary targets potentially observable in single-field mode. The feasibility of such observations will strongly be dependent on the ability of the control software of GRAVITY to track objects moving at high rate on the sky (differential motion ˜f 10 mas.s^{-1}). Although the dual-field mode could allow to increase the sample of small binary asteroids observable, it seems to be currently unfeasible given the high differential motion of asteroids.

  17. An experimental path to constraining the origin of Jupiter’s Trojan asteroids by identifying chemical fingerprints

    NASA Astrophysics Data System (ADS)

    Blacksberg, Jordana; Mahjoub, Ahmed; Poston, Michael; Brown, Mike; Eiler, John; Ehlmann, Bethany; Hand, Kevin; Carlson, Robert W.; Hodyss, Robert; Wong, Ian

    2015-11-01

    We present an experimental study aimed at exploring the hypothesis suggested by recent dynamical models - that the Jupiter Trojan asteroids originated in the outer solar system, were scattered by the same instability responsibility for the radical rearrangement of the giant planets, and were subsequently captured in their current location (e.g. Morbidelli et al., 2005, Nesvorny et al., 2013). We seek to identify spectroscopic, chemical and isotopic properties that can tie the Trojan populations to these evolutionary pathways, providing experimental support of dynamical models, and providing testable hypotheses that can feed into the design of experiments that might be performed on potential future missions to these and other primitive bodies.We present the results of experiments devised to explore the hypothesis that Kuiper Belt Objects (KBOs) represent the parent populations of the Trojan asteroids. Numerous thin ice films composed of select solar system volatiles (H2O, H2S, CH3OH, NH3) were grown in various mixtures to simulate compositional changes of icy bodies as a function of volatility and radial distance of formation from the Sun. Subsequent processing of these icy bodies was simulated using electron irradiation and heating. Visible reflectance spectra show significant reddening when H2S is present. Mid-infrared spectra confirm the formation of non-volatile sulfur-containing molecules in the products of H2S-containing ices. These experiments suggest that the presence of specific sulfur-bearing chemical species may play an important role in the colors of both the KBOs and Trojans today. Finally, we discuss the role of the silicate component expected on the surface of the Trojan asteroids (Emery et al., 2006), and the implications of a surface composed of silicates in intimate contact with the nonvolatile organic residues generated by ice irradiation.This work has been supported by the Keck Institute for Space Studies (KISS). The research described here was

  18. Rotational breakup as the origin of small binary asteroids.

    PubMed

    Walsh, Kevin J; Richardson, Derek C; Michel, Patrick

    2008-07-10

    Asteroids with satellites are observed throughout the Solar System, from subkilometre near-Earth asteroid pairs to systems of large and distant bodies in the Kuiper belt. The smallest and closest systems are found among the near-Earth and small inner main-belt asteroids, which typically have rapidly rotating primaries and close secondaries on circular orbits. About 15 per cent of near-Earth and main-belt asteroids with diameters under 10 km have satellites. The mechanism that forms such similar binaries in these two dynamically different populations was hitherto unclear. Here we show that these binaries are created by the slow spinup of a 'rubble pile' asteroid by means of the thermal YORP (Yarkovsky-O'Keefe-Radzievskii-Paddack) effect. We find that mass shed from the equator of a critically spinning body accretes into a satellite if the material is collisionally dissipative and the primary maintains a low equatorial elongation. The satellite forms mostly from material originating near the primary's surface and enters into a close, low-eccentricity orbit. The properties of binaries produced by our model match those currently observed in the small near-Earth and main-belt asteroid populations, including 1999 KW(4) (refs 3, 4).

  19. LONG-TERM STABLE EQUILIBRIA FOR SYNCHRONOUS BINARY ASTEROIDS

    SciTech Connect

    Jacobson, Seth A.; Scheeres, Daniel J.

    2011-07-20

    Synchronous binary asteroids may exist in a long-term stable equilibrium, where the opposing torques from mutual body tides and the binary YORP (BYORP) effect cancel. Interior of this equilibrium, mutual body tides are stronger than the BYORP effect and the mutual orbit semimajor axis expands to the equilibrium; outside of the equilibrium, the BYORP effect dominates the evolution and the system semimajor axis will contract to the equilibrium. If the observed population of small (0.1-10 km diameter) synchronous binaries are in static configurations that are no longer evolving, then this would be confirmed by a null result in the observational tests for the BYORP effect. The confirmed existence of this equilibrium combined with a shape model of the secondary of the system enables the direct study of asteroid geophysics through the tidal theory. The observed synchronous asteroid population cannot exist in this equilibrium if described by the canonical 'monolithic' geophysical model. The 'rubble pile' geophysical model proposed by Goldreich and Sari is sufficient, however it predicts a tidal Love number directly proportional to the radius of the asteroid, while the best fit to the data predicts a tidal Love number inversely proportional to the radius. This deviation from the canonical and Goldreich and Sari models motivates future study of asteroid geophysics. Ongoing BYORP detection campaigns will determine whether these systems are in an equilibrium, and future determination of secondary shapes will allow direct determination of asteroid geophysical parameters.

  20. Rotational breakup as the origin of small binary asteroids.

    PubMed

    Walsh, Kevin J; Richardson, Derek C; Michel, Patrick

    2008-07-10

    Asteroids with satellites are observed throughout the Solar System, from subkilometre near-Earth asteroid pairs to systems of large and distant bodies in the Kuiper belt. The smallest and closest systems are found among the near-Earth and small inner main-belt asteroids, which typically have rapidly rotating primaries and close secondaries on circular orbits. About 15 per cent of near-Earth and main-belt asteroids with diameters under 10 km have satellites. The mechanism that forms such similar binaries in these two dynamically different populations was hitherto unclear. Here we show that these binaries are created by the slow spinup of a 'rubble pile' asteroid by means of the thermal YORP (Yarkovsky-O'Keefe-Radzievskii-Paddack) effect. We find that mass shed from the equator of a critically spinning body accretes into a satellite if the material is collisionally dissipative and the primary maintains a low equatorial elongation. The satellite forms mostly from material originating near the primary's surface and enters into a close, low-eccentricity orbit. The properties of binaries produced by our model match those currently observed in the small near-Earth and main-belt asteroid populations, including 1999 KW(4) (refs 3, 4). PMID:18615078

  1. BINARY ASTEROID ENCOUNTERS WITH TERRESTRIAL PLANETS: TIMESCALES AND EFFECTS

    SciTech Connect

    Fang, Julia; Margot, Jean-Luc

    2012-01-15

    Many asteroids that make close encounters with terrestrial planets are in a binary configuration. Here, we calculate the relevant encounter timescales and investigate the effects of encounters on a binary's mutual orbit. We use a combination of analytical and numerical approaches with a wide range of initial conditions. Our test cases include generic binaries with close, moderate, and wide separations, as well as seven well-characterized near-Earth binaries. We find that close approaches (<10 Earth radii) occur for almost all binaries on 1-10 million year timescales. At such distances, our results suggest substantial modifications to a binary's semimajor axis, eccentricity, and inclination, which we quantify. Encounters within 30 Earth radii typically occur on sub-million year timescales and significantly affect the wider binaries. Important processes in the lives of near-Earth binaries, such as tidal and radiative evolution, can be altered or stopped by planetary encounters.

  2. Origin of Martian Moons from Binary Asteroid Dissociation

    NASA Technical Reports Server (NTRS)

    Landis, Geoffrey A.; Lyons, Valerie J. (Technical Monitor)

    2001-01-01

    The origin of the Martian moons Deimos and Phobos is controversial. A common hypothesis for their origin is that they are captured asteroids, but the moons show no signs of having been heated by passage through a (hypothetical) thick martian atmosphere, and the mechanism by which an asteroid in solar orbit could shed sufficient orbital energy to be captured into Mars orbit has not been previously elucidated. Since the discovery by the space probe Galileo that the asteroid Ida has a moon 'Dactyl', a significant number of asteroids have been discovered to have smaller asteroids in orbit about them. The existence of asteroid moons provides a mechanism for the capture of the Martian moons (and the small moons of the outer planets). When a binary asteroid makes a close approach to a planet, tidal forces can strip the moon from the asteroid. Depending on the phasing, either or both can then be captured. Clearly, the same process can be used to explain the origin of any of the small moons in the solar system.

  3. Asteroid 2013 ND15: Trojan companion to Venus, PHA to the Earth

    NASA Astrophysics Data System (ADS)

    de la Fuente Marcos, C.; de la Fuente Marcos, R.

    2014-04-01

    Venus has three known co-orbitals: (322756) 2001 CK32, 2002 VE68 and 2012 XE133. The first two have absolute magnitudes 18 < H < 21. The third one, significantly smaller at H = 23.4 mag, is a recent discovery that signals the probable presence of many other similar objects: small transient companions to Venus that are also potentially hazardous asteroids (PHAs). Here, we study the dynamical evolution of the recently discovered asteroid 2013 ND15. At H = 24.1 mag, this minor body is yet another small Venus co-orbital and PHA, currently close to the Lagrangian point L4 and following the most eccentric path found so far for objects in this group. This transient Trojan will leave the 1:1 mean motion resonance within a few hundred years although it could be a recurrent librator. Due to its high eccentricity (0.6), its dynamics is different from that of the other three known Venus co-orbitals even if they all are near-Earth objects (NEOs). A Monte Carlo simulation that uses the orbital data and discovery circumstances of the four objects as proxies to estimate the current size of this population, indicates that the number of high-eccentricity, low-inclination Venus co-orbital NEOs may have been greatly underestimated by current models. Three out of four known objects were discovered with solar elongation at perigee greater than 135° even if visibility estimates show that less than 4 per cent of these objects are expected to reach perigee at such large elongations. Our calculations suggest that the number of minor bodies with sizes above 150 m currently engaged in co-orbital motion with Venus could be at least one order of magnitude larger than usually thought; the number of smaller bodies could easily be in many thousands. These figures have strong implications on the fraction of existing PHAs that can barely be detected by current surveys. Nearly 70 per cent of the objects discussed here have elongation at perigee <90° and 65 per cent are prospective PHAs.

  4. Using binary asteroids to explore the interior geophysics of rubble-pile asteroids

    NASA Astrophysics Data System (ADS)

    Scheeres, D.; Jacobson, S.; McMahon, J.; Hirabayashi, M.

    2014-07-01

    The internal geophysics of small rubble-pile asteroids are largely unexplored, with standard geophysical theories of strength and dissipation not being well matched to the extreme environment these bodies exist in. Interior pressures within rapidly spinning rubble piles are computed to be as small as a few Pascals, a regime in which small non-gravitational forces not considered for larger bodies may become important. The limited research done on the geophysics of such bodies has suggested that the standard geophysical models for internal energy dissipation in this regime require significant modification [1], changing some of the fundamental relations between size and strength. Binary asteroid systems provide a unique opportunity for developing constraints and deeper understanding of the magnitude and operation of tidal dissipation within rubble-pile bodies. Recently, Jacobson and Scheeres [2] proposed that the most common class of binary asteroid systems, those with a synchronized secondary and rapidly spinning primary, may be in an equilibrium state where contractive Binary YORP forces balance against expansive tidal torques due to tidal distortion of the primary body. In such systems it becomes possible to develop estimates of the ratio of tidal dissipation number over tidal Love number, Q/k. The predicted equilibrium semi-major axes for such binary asteroid systems (based on presumed values for the Binary YORP force and Q/k values) has been seen to be consistent with the observed sizes of many of these systems (see figure). To refine the estimates for this ratio it is necessary to both confirm the existence of binary asteroids in such an equilibrium state and develop a better understanding of what value the Binary YORP coefficient of binary systems will have [3]. Recently, it has been verified that the spacecraft-accessible binary asteroid 1996 FG_3 is in such an equilibrium state [4]. The combined detection of such an equilibrium coupled with knowledge about

  5. Libration motion of Trojan asteroids taking into account their orbital inclinations

    NASA Astrophysics Data System (ADS)

    Zagretdinov, R. V.

    1986-08-01

    An intermediate orbit for 1/1 resonance in the circular restricted three body problem is suggested taking into account the orbital inclinations. The intermediate orbit is used to determine the libration orbits of 38 numbered minor planets of Trojan group in the cases of zero and non-zero inclinations. A satisfactory agreement of the results obtained for Trojan Stentor (2146) with those by Bein is obtained.

  6. Internal Structure and Figures of Binary Asteroids

    NASA Astrophysics Data System (ADS)

    Hestroffer, Daniel

    2005-07-01

    The goal of this proposal is to obtain very important information on the internal structure of a number of asteroids, and insight on the gravitational reaccumulation-process after a catastrophic disruptive collision. High resolutions observations with the HST/FGS interferometer are proposed to obtain high precision data for the topographic shape and size of a number of selected asteroids. Here we focus on objects with satellites, hence with known masses, so that the bulk density and porosity will be derived in the most accurate manner. This will yield plausible estimates on the internal properties of the objects, test wether they are close or not to figures of equilibrium {in terms of shape and adimensional rotational frequency}, and provide estimates of their relative density. The HST/FGS in interferometric mode is an ideal facility to carry out this program.

  7. The Evolutionary Outcomes of Expansive Binary Asteroid Systems

    NASA Astrophysics Data System (ADS)

    McMahon, Jay W.

    2016-10-01

    Singly synchronous binary asteroid systems have several evolutionary end-states, which depend heavily on the BYORP effect. In the case of expansive BYORP, the binary system could evolve to become a wide asynchronous binary system (Jacobson, et al 2014), or the system could expand far enough to become disrupted to form a heliocentric pair (Vokrouhlicky et al 2008). Cuk et al (2011) found that upon expanding the secondary will quickly become asynchronous, and will end up re-establishing synchronous rotation with the opposite attitude, causing the binary orbit to subsequently contract. The distinction between these outcomes depends on whether the secondary asteroid stays synchronized, which keeps the BYORP effect active and the orbit expanding. As the orbit expands, the secondary libratation will expand, and the libration will also causes large variations in the binary orbit due to the elongation of the secondary. If the eccentricity and libration are bound to small enough values the system can expand significantly. This work discusses the stability of the libration and orbital motion as a binary expands from a wide variety of simulation runs with various parameters. We investigate how the strength of tides and BYORP change the stability of the librational motion; an important factor is the speed of BYORP expansion as slower expansion allows tides to have a more stabilizing effect. We also investigate the effect of heliocentric orbit semimajor axis and eccentricity. We find that resonances between the coupled orbit-libration frequencies and the heliocentric orbit cause instability in the binary orbit eccentricity which produces a strong preference for wide binary production, especially amongst retrograde binary systems. This instability also becomes stronger with large heliocentric eccentricities. Prograde binaries are more stable and can possible grow to become asteroid pairs. We find that even in the presence of tides, reestablishment of synchronous spin into a

  8. Markov Chain Monte-Carlo Orbit Computation for Binary Asteroids

    NASA Astrophysics Data System (ADS)

    Oszkiewicz, D.; Hestroffer, D.; Pedro, David C.

    2013-11-01

    We present a novel method of orbit computation for resolved binary asteroids. The method combines the Thiele, Innes, van den Bos method with a Markov chain Monte Carlo technique (MCMC). The classical Thiele-van den Bos method has been commonly used in multiple applications before, including orbits of binary stars and asteroids; conversely this novel method can be used for the analysis of binary stars, and of other gravitationally bound binaries. The method requires a minimum of three observations (observing times and relative positions - Cartesian or polar) made at the same tangent plane - or close enough for enabling a first approximation. Further, the use of the MCMC technique for statistical inversion yields the whole bundle of possible orbits, including the one that is most probable. In this new method, we make use of the Metropolis-Hastings algorithm to sample the parameters of the Thiele-van den Bos method, that is the orbital period (or equivalently the double areal constant) together with three randomly selected observations from the same tangent plane. The observations are sampled within their observational errors (with an assumed distribution) and the orbital period is the only parameter that has to be tuned during the sampling procedure. We run multiple chains to ensure that the parameter phase space is well sampled and that the solutions have converged. After the sampling is completed we perform convergence diagnostics. The main advantage of the novel approach is that the orbital period does not need to be known in advance and the entire region of possible orbital solutions is sampled resulting in a maximum likelihood solution and the confidence regions. We have tested the new method on several known binary asteroids and conclude a good agreement with the results obtained with other methods. The new method has been implemented into the Gaia DPAC data reduction pipeline and can be used to confirm the binary nature of a suspected system, and for deriving

  9. Two New Binaries and Continuing Observations of Hungaria Group Asteroids

    NASA Astrophysics Data System (ADS)

    Warner, Brian D.

    2015-04-01

    Analysis of CCD photometry for five asteroids lead to the discovery of two new binary objects. (190208) 2006 AQ, is a rare “wide binary” example with a primary period of 182 h and secondary period of 2.62002 h. 2014 WZ120 is a near-Earth asteroid with a primary period of 3.361 h and orbital period of 13.665 h. The estimated effective diameter ratio for the pair is Ds/Dp >= 0.32. The other three asteroids, 1103 Sequoia, 2083 Smither, and 3880 Kaiserman, all members of the Hungaria group, show varying signs of a secondary period but no mutual events that would confirm the existence of a satellite.

  10. Bayesian Statistical Approach To Binary Asteroid Orbit Determination

    NASA Astrophysics Data System (ADS)

    Dmitrievna Kovalenko, Irina; Stoica, Radu S.

    2015-08-01

    Orbit determination from observations is one of the classical problems in celestial mechanics. Deriving the trajectory of binary asteroid with high precision is much more complicate than the trajectory of simple asteroid. Here we present a method of orbit determination based on the algorithm of Monte Carlo Markov Chain (MCMC). This method can be used for the preliminary orbit determination with relatively small number of observations, or for adjustment of orbit previously determined.The problem consists on determination of a conditional a posteriori probability density with given observations. Applying the Bayesian statistics, the a posteriori probability density of the binary asteroid orbital parameters is proportional to the a priori and likelihood probability densities. The likelihood function is related to the noise probability density and can be calculated from O-C deviations (Observed minus Calculated positions). The optionally used a priori probability density takes into account information about the population of discovered asteroids. The a priori probability density is used to constrain the phase space of possible orbits.As a MCMC method the Metropolis-Hastings algorithm has been applied, adding a globally convergent coefficient. The sequence of possible orbits derives through the sampling of each orbital parameter and acceptance criteria.The method allows to determine the phase space of every possible orbit considering each parameter. It also can be used to derive one orbit with the biggest probability density of orbital elements.

  11. The Cool Surfaces of Binaries Near-Earth Asteroids

    NASA Astrophysics Data System (ADS)

    Delbo, Marco; Walsh, K.; Mueller, M.

    2008-09-01

    We present results from thermal-infrared observations of binary near-Earth asteroids (NEAs). These objects, in general, have surface temperatures cooler than the average values for non-binary NEAs. We discuss how this may be evidence of higher-than-average surface thermal inertia. The comparison of these binary NEAs with all NEAs and rapidly rotating NEAs suggests a binary formation mechanism capable of altering surface properties, possibly removing regolith: an obvious candidate is the YORP effect. --- Acknowledgments This research was carried out while Marco Delbo and Kevin Walsh were Henri Poincare Fellows at the Observatoire de la Cote d'Azur. The Henri Poincare Fellowship is funded by the CNRS-INSU, the Conseil General des Alpes-Maritimes and the Rotary International -- District 1730.

  12. Formation of the wide asynchronous binary asteroid population

    SciTech Connect

    Jacobson, Seth A.; Scheeres, Daniel J.; McMahon, Jay

    2014-01-01

    We propose and analyze a new mechanism for the formation of the wide asynchronous binary population. These binary asteroids have wide semimajor axes relative to most near-Earth and main belt asteroid systems. Confirmed members have rapidly rotating primaries and satellites that are not tidally locked. Previously suggested formation mechanisms from impact ejecta, from planetary flybys, and directly from rotational fission events cannot satisfy all of the observations. The newly hypothesized mechanism works as follows: (1) these systems are formed from rotational fission, (2) their satellites are tidally locked, (3) their orbits are expanded by the binary Yarkovsky-O'Keefe-Radzievskii-Paddack (BYORP) effect, (4) their satellites desynchronize as a result of the adiabatic invariance between the libration of the secondary and the mutual orbit, and (5) the secondary avoids resynchronization because of the YORP effect. This seemingly complex chain of events is a natural pathway for binaries with satellites that have particular shapes, which define the BYORP effect torque that acts on the system. After detailing the theory, we analyze each of the wide asynchronous binary members and candidates to assess their most likely formation mechanism. Finally, we suggest possible future observations to check and constrain our hypothesis.

  13. Formation of the Wide Asynchronous Binary Asteroid Population

    NASA Astrophysics Data System (ADS)

    Jacobson, Seth A.; Scheeres, Daniel J.; McMahon, Jay

    2014-01-01

    We propose and analyze a new mechanism for the formation of the wide asynchronous binary population. These binary asteroids have wide semimajor axes relative to most near-Earth and main belt asteroid systems. Confirmed members have rapidly rotating primaries and satellites that are not tidally locked. Previously suggested formation mechanisms from impact ejecta, from planetary flybys, and directly from rotational fission events cannot satisfy all of the observations. The newly hypothesized mechanism works as follows: (1) these systems are formed from rotational fission, (2) their satellites are tidally locked, (3) their orbits are expanded by the binary Yarkovsky-O'Keefe-Radzievskii-Paddack (BYORP) effect, (4) their satellites desynchronize as a result of the adiabatic invariance between the libration of the secondary and the mutual orbit, and (5) the secondary avoids resynchronization because of the YORP effect. This seemingly complex chain of events is a natural pathway for binaries with satellites that have particular shapes, which define the BYORP effect torque that acts on the system. After detailing the theory, we analyze each of the wide asynchronous binary members and candidates to assess their most likely formation mechanism. Finally, we suggest possible future observations to check and constrain our hypothesis.

  14. Results of Observations of Occultations of Stars by Main-Belt and Trojan Asteroids, and the Promise of Gaia

    NASA Astrophysics Data System (ADS)

    Dunham, David W.; Herald, David Russell; Preston, Steven; Loader, Brian; Bixby Dunham, Joan

    2016-10-01

    For 40 years, the sizes and shapes of scores of asteroids have been determined from observations of asteroidal occultations, and many hundreds of high-precision positions of the asteroids relative to stars have been measured. Earlier this year, the 3000th observation of an asteroidal occultation was documented. Some of the first evidence for satellites of asteroids was obtained from the early efforts; now, the orbits and sizes of some satellites discovered by other means have been refined from occultation observations. Also, several close binary stars have been discovered, and the angular diameters of some stars have been measured from analysis of these observations. The International Occultation Timing Association (IOTA) coordinates this activity worldwide, from predicting and publicizing the events, to accurately timing the occultations from as many stations as possible, and publishing and archiving the observations. The first observations were timed visually, but now nearly all observations are either video-recorded, or recorded with CCD drift scans, allowing small magnitude-drop events to be recorded, and resulting in more consistent results. Techniques have been developed allowing one or two observers to set up multiple stations with small telescopes, video cameras, and timers, thereby recording many chords, even across a whole asteroid; some examples will be shown.Later this year, the first release of Gaia data will allow us to greatly improve the vast star catalog that we use for both predicting and analyzing these events. Although the first asteroidal data will wait until the 4th Gaia release, before that, we can greatly improve the orbits of asteroids that have occulted 3 or more stars in the past so that we can start computing the paths of future occultations by them to few km accuracy. In a couple of years, we'll be able to realistically predict one to two orders of magnitude more events than we can now, allowing efforts to be concentrated on smaller

  15. On the Trojan asteroid sample and return mission via solar-power sail -- an innovative engineering demonstration

    NASA Astrophysics Data System (ADS)

    Kawaguchi, J.; Mori, O.; Shirasawa, Y.; Yoshikawa, M.

    2014-07-01

    The science and engineering communities in the world are seeking what comes next. Especially for asteroids and comets, as those objects lie in relatively far area in our solar system, and new engineering solutions are essential to explore them. JAXA has studied the next-step mission since 2000, a solar-power sail demonstrator combining the use of photon propulsion with electric propulsion, ion thruster, targeting the untrodden challenge for the sample return attempt from a Trojan asteroid around the libration points in the Sun-Jupiter system. The Ikaros spacecraft was literally developed and launched as a preliminary technology demonstration. The mission will perform in-situ measurement and on-site analysis of the samples in addition to the sample return to the Earth, and will also deploy a small lander on the surface for collecting surface samples and convey them to the mother spacecraft. From a scientific point of view, there is an enormous reward in the most primitive samples containing information about the ancient solar system and also about the origin of life in our solar system. JAXA presently looks for international partners to develop and build the lander. The presentation will elaborate the current mission scenario as well as what we think the international collaboration will be.

  16. Radar Imaging of Binary Near-Earth Asteroid 2004 DC

    NASA Astrophysics Data System (ADS)

    Taylor, Patrick A.; Margot, J. L.; Nolan, M. C.; Benner, L. A.; Ostro, S. J.; Giorgini, J. D.; Magri, C.

    2006-09-01

    Arecibo S-band (2380 MHz, 13 cm) and Goldstone X-band (8560 MHz, 3.5 cm) radar observations on June 2-6, 2006 show that Apollo asteroid 2004 DC is a binary system [IAU CBET 535]. Preliminary estimates of the diameters, based on visible range extents in the delay-Doppler images, are 300 m for the primary and 60 m for the secondary. The motion of the secondary in the delay-Doppler images suggests an orbital period of roughly 23 hours and a maximum primary-to-secondary separation of at least 0.6 km. The bandwidth of the primary increases from May 29 to June 3, then decreases until the end of observations on June 6, implying 2004 DC was viewed closest to equatorial on June 3. Assuming an equatorial view, the bandwidth suggests a rotation period of about 2 hours, which is in agreement with lightcurve observations [R. Behrend, pers. comm.]. The radar albedo and circular polarization ratio are 0.4 and 0.8 at S-band and 0.3 and unity at X-band. The circular polarization ratios are larger than those of the majority of radar-observed asteroids and imply that 2004 DC has extreme decimeter-scale near-surface roughness. We will estimate the parameters of the mutual orbit and the shape of the primary, and will place the orbital and physical properties of the system into the context of the existing binary near-Earth asteroid population.

  17. The Binary Nature of the Asteroid 2242 Balaton

    NASA Astrophysics Data System (ADS)

    Marchini, Alessandro; Bacci, Paolo; Carbognani, Albino; Franco, Lorenzo; Klinglesmith, Daniel A., III; Papini, Riccardo; Pravec, Petr; Pray, Donald P.; Salvaggio, F.

    2016-10-01

    Initial observations of 2242 Balaton indicated a rotation period of about 2.8 hours with some attenuation events. Further observations and analysis showed that 2242 is a binary asteroid with a primary period of 2.7979 ± 0.0001 h and amplitude of 0.18 mag; the orbital period of the secondary is 12.96 ± 0.01 h. Mutual events that are 0.03 to 0.08 magnitude deep indicate a lower limit on the secondary-to-primary mean-diameter ratio of 0.25. From sparse photometric data we also derived H = 13.31 ± 0.05, G = 0.22 ± 0.04.

  18. Three Additional Candidates for the Group of Very Wide Binary Asteroids

    NASA Astrophysics Data System (ADS)

    Warner, Brian D.

    2016-10-01

    The very wide binary asteroids (VWBA) are a subgroup of binary asteroids that exhibit very long primary periods and, mostly, short secondary periods that are similar to those of the primary of "normal" small binary asteroids. It is unlikely that confirming mutual events will be seen by photometric observations, mostly because the orbital periods of the assumed satellites will be on the order of days. This paper introduces three additional candidates for this subgroup: (215442) 2002 MQ3, 2009 EC, and 2016 BU13. All three are considered to be among the more convincing examples that such systems exist.

  19. Biases affecting radar detection of binary near-Earth Asteroids

    NASA Astrophysics Data System (ADS)

    Benner, Lance A. M.; Brozovic, Marina; Naidu, Shantanu P.

    2016-10-01

    Radar observations at Arecibo and Goldstone provide a powerful tool for the discovery, characterization, and orbit estimation of binary near-Earth asteroids (NEAs). To date, 73% of binary and triple NEA systems have been discovered by radar and 87% have been detected by radar. Here we describe biases not discussed in detail in the peer-reviewed literature that can adversely affect radar detection of NEA satellites. In a Doppler-only echo power spectrum, most NEA binaries have a rapidly-spinning primary that appears as a broad echo, and a slowly orbiting, tidally-locked companion that appears as a narrow spike superimposed on the primary echo. The most important factor for detection of a companion is the signal-to-noise ratio (SNR), which is proportional to (r -4)(D 3/2)(P 1/2), where r is the distance, D is the diameter, and P is the rotation period. Low SNRs occur primarily due to the distance, a small diameter, and rapid rotation and necessitate coarse frequency resolution that limits detection of narrow spikes. Spikes in echo power spectra also occur due to glints, self noise, and radar albedo features, so confirmation of a binary requires delay-Doppler images that show two separate echoes whose positions change with time. Most companions appear tidally locked, but ~25% rotate more rapidly than their orbital periods. For example, in October 2001 the companion of 1998 ST27 was not obvious in echo power spectra or in single delay-Doppler images but was seen only when all the images from each day were summed, revealing a trail of faint pixels. The satellite SNRs were weak because its rotation is much more rapid than its orbital period. Other important factors include differences between the bandwidth of the companion and the Doppler resolution; weak SNRs due to a small diameter; self noise due to a small number of Fourier transforms; rapid orbital motion that decreases the SNR of the satellite into the noise; failure to inspect the data at sufficiently high Doppler

  20. Dynamics of Satellites in Binary Near-Earth Asteroid Systems: A Study Based on Radar Observations

    NASA Astrophysics Data System (ADS)

    Naidu, Shantanu

    In the past 15 years, three previously unrecognized sub-populations of near-Earth asteroids (NEAs) have been discovered. About 15% of NEAs are binaries, at least 10% of NEAs are contact binaries, and dozens of asteroid pairs have been identified. Numerous science questions have arisen about the formation and evolution processes of these systems and about the inter-relationships between these groups. Addressing these questions informs us about a wide range of important solar system processes that shape small bodies and planetesimals. Here I have chosen to focus on providing one of the most complete characterizations of a binary system among all known asteroid binaries, and on studying the spin-orbit interactions in this and 8 additional binary systems. One hypothesis that has not been fully explored is the possibility of chaotic rotation of asteroid satellites and the impact that such a state has on the evolution of the binary systems. I examine this problem as well as the possibility of detecting librational motions in synchronous satellites. Because the Arecibo and Goldstone radar systems enable superb characterizations of binaries and NEAs in general, this dissertation makes abundant use of radar data. Radar observations provide images of asteroids at decameter resolution, and these images can be inverted to determine the 3D shapes of the components, which are essential to properly model the system dynamics. Radar data also enable precise determination of the mutual orbit, which is another crucial ingredient. In the first two chapters of the dissertation, I describe the observations and physical characterizations of asteroid 2000~ET70 and binary asteroid 2000 DP107. The characterization of 2000 DP107 includes size, shape, spin, mass, and density of each component, making this binary one of the best-characterized asteroid binary to date. In the last chapter of the dissertation, I describe a computationally efficient fourth-order numerical integrator that I used to

  1. Collisional Histories of Comets and Trojan Asteroids: Diopside, Magnesite, and Fayalite Impact Studies

    NASA Technical Reports Server (NTRS)

    Lederer, S. M.; Jensen, E. A.; Wooden, D. H.; Lindsay, S. S.; Nakamura-Messenger, K.; Smith, D. C.; Keller, L. P.; Cintala, M. J.; Zolensky, M. E.

    2012-01-01

    Comets and asteroids have weathered dynamic histories, as evidenced by their rough surfaces. The Nice model describes a violent reshuffling of small bodies during the Late Heavy Bombardment, with collisions acting to grind these planetesimals away. This creates an additional source of impact material that can re-work the surfaces of the larger bodies over the lifetime of the solar system. Here, we investigate the possibility that signatures due to impacts (e.g. from micrometeoroids or meteoroids) could be detected in their spectra, and how that can be explained by the physical manifestation of shock in the crystalline structure of minerals. All impact experiments were conducted in the Johnson Space Center Experimental Impact Laboratory using the vertical gun. Impact speeds ranged from approx.2.0 km/s to approx.2.8 km/s. All experiments were conducted at room temperature. Minerals found in comets and asteroids were chosen as targets, including diopside (MgCaSi2O6, monoclinic pyroxene), magnesite (MgCO3, carbonate), and fayalite (FeSiO4, olivine). Impacted samples were analyzed using a Fourier Transform Infrared Spectrometer (FTIR) and a Transmission Electron Microscope (TEM). Absorbance features in the 8-13 m spectral region demonstrate relative amplitude changes as well as wavelength shifts. Corresponding TEM images exhibit planar shock dislocations in the crystalline structure, attributed to deformation at high strain and low temperatures. Elongating or shortening the axes of the crystalline structure of forsterite (Mg2SiO4, olivine) using a discrete dipole approximation model (Lindsay et al., submitted) yields changes in spectral features similar to those observed in our impacted laboratory minerals.

  2. The Asteroid Impact Mission (AIM): Studying the geophysics of small binaries, measuring asteroid deflection and studying impact physics

    NASA Astrophysics Data System (ADS)

    Kueppers, Michael; Michel, Patrick; AIM team

    2016-10-01

    Binary asteroids and their formation mechanisms are of particular interest for understanding the evolution of the small bodies in the solar system. Also, hazards to Earth from impact of near-Earth asteroids and their mitigation have drawn considerable interest over the last decades.Those subjects are both addressed by ESA's Asteroid Impact mission, which is part of the Asteroid Impact & Deflection Assessment (AIDA) currently under study in collaboration between NASA and ESA. NASA's DART mission will impact a projectile into the minor component of the binary near-Earth asteroid (65803) Didymos in 2022. The basic idea is to demonstrate the effect of the impact on the orbital period of the secondary around the primary. ESA's AIM will monitor the Didymos system for several months around the DART impact time.AIM will be launched in aurumn 2020. It is foreseen to arrive at Didymos in April 2022. The mission takes advantage of a close approach of Didymos to Earth. The next opportunity would arise in 2040 only.AIM will stay near Didymos for approximately 6 months. Most of the time it will be placed on the illuminated side of the system, at distances of approximately 35 km and 10 km. AIM is expected to move away from Didymos for some time around the DART impact.The reference payload for AIM includes two visual imagers, a hyperspectral camera, a lidar, a thermal infrared imager, a monostatic high frequency radar, and a bistatic low frequency radar. In addition, AIM will deploy a small lander on the secondary asteroid, and two cubesats that will be used for additional, more risky investigations close to or on the surface of the asteroid.Major contributions from AIM are expected in the study of the geophysics of small asteroids (including for the first time, radar measurements of an interior structure), the formation of binary asteroids, the momentum enhancement factor from the DART impact (through measuring the mass and the change of orbit of the seondary), and impact physics

  3. Binary asteroid population. 3. Secondary rotations and elongations

    NASA Astrophysics Data System (ADS)

    Pravec, P.; Scheirich, P.; Kušnirák, P.; Hornoch, K.; Galád, A.; Naidu, S. P.; Pray, D. P.; Világi, J.; Gajdoš, Š.; Kornoš, L.; Krugly, Yu. N.; Cooney, W. R.; Gross, J.; Terrell, D.; Gaftonyuk, N.; Pollock, J.; Husárik, M.; Chiorny, V.; Stephens, R. D.; Durkee, R.; Reddy, V.; Dyvig, R.; Vraštil, J.; Žižka, J.; Mottola, S.; Hellmich, S.; Oey, J.; Benishek, V.; Kryszczyńska, A.; Higgins, D.; Ries, J.; Marchis, F.; Baek, M.; Macomber, B.; Inasaridze, R.; Kvaratskhelia, O.; Ayvazian, V.; Rumyantsev, V.; Masi, G.; Colas, F.; Lecacheux, J.; Montaigut, R.; Leroy, A.; Brown, P.; Krzeminski, Z.; Molotov, I.; Reichart, D.; Haislip, J.; LaCluyze, A.

    2016-03-01

    We collected data on rotations and elongations of 46 secondaries of binary and triple systems among near-Earth, Mars-crossing and small main belt asteroids. 24 were found or are strongly suspected to be synchronous (in 1:1 spin-orbit resonance), and the other 22, generally on more distant and/or eccentric orbits, were found or are suggested to have asynchronous rotations. For 18 of the synchronous secondaries, we constrained their librational angles, finding that their long axes pointed to within 20° of the primary on most epochs. The observed anti-correlation of secondary synchroneity with orbital eccentricity and the limited librational angles agree with the theories by Ćuk and Nesvorný (Ćuk, M., Nesvorný, D. [2010]. Icarus 207, 732-743) and Naidu and Margot (Naidu, S.P., Margot, J.-L. [2015]. Astron. J. 149, 80). A reason for the asynchronous secondaries being on wider orbits than synchronous ones may be longer tidal circularization time scales at larger semi-major axes. The asynchronous secondaries show relatively fast spins; their rotation periods are typically < 10 h. An intriguing observation is a paucity of chaotic secondary rotations; with an exception of (35107) 1991 VH, the secondary rotations are single-periodic with no signs of chaotic rotation and their periods are constant on timescales from weeks to years. The secondary equatorial elongations show an upper limit of a2 /b2 ∼ 1.5 . The lack of synchronous secondaries with greater elongations appears consistent, considering uncertainties of the axis ratio estimates, with the theory by Ćuk and Nesvorný that predicts large regions of chaotic rotation in the phase space for a2 /b2 ≳√{ 2 } . Alternatively, secondaries may not form or stay very elongated in gravitational (tidal) field of the primary. It could be due to the secondary fission mechanism suggested by Jacobson and Scheeres (Jacobson, S.A., Scheeres, D.J. [2011]. Icarus 214, 161-178), as its efficiency is correlated with the

  4. First known terrestrial impact of a binary asteroid from a main belt breakup event.

    PubMed

    Ormö, Jens; Sturkell, Erik; Alwmark, Carl; Melosh, Jay

    2014-01-01

    Approximately 470 million years ago one of the largest cosmic catastrophes occurred in our solar system since the accretion of the planets. A 200-km large asteroid was disrupted by a collision in the Main Asteroid Belt, which spawned fragments into Earth crossing orbits. This had tremendous consequences for the meteorite production and cratering rate during several millions of years following the event. The 7.5-km wide Lockne crater, central Sweden, is known to be a member of this family. We here provide evidence that Lockne and its nearby companion, the 0.7-km diameter, contemporaneous, Målingen crater, formed by the impact of a binary, presumably 'rubble pile' asteroid. This newly discovered crater doublet provides a unique reference for impacts by combined, and poorly consolidated projectiles, as well as for the development of binary asteroids. PMID:25340551

  5. First known terrestrial impact of a binary asteroid from a main belt breakup event.

    PubMed

    Ormö, Jens; Sturkell, Erik; Alwmark, Carl; Melosh, Jay

    2014-10-23

    Approximately 470 million years ago one of the largest cosmic catastrophes occurred in our solar system since the accretion of the planets. A 200-km large asteroid was disrupted by a collision in the Main Asteroid Belt, which spawned fragments into Earth crossing orbits. This had tremendous consequences for the meteorite production and cratering rate during several millions of years following the event. The 7.5-km wide Lockne crater, central Sweden, is known to be a member of this family. We here provide evidence that Lockne and its nearby companion, the 0.7-km diameter, contemporaneous, Målingen crater, formed by the impact of a binary, presumably 'rubble pile' asteroid. This newly discovered crater doublet provides a unique reference for impacts by combined, and poorly consolidated projectiles, as well as for the development of binary asteroids.

  6. Numerical analysis of orbital motion around a contact binary asteroid system

    NASA Astrophysics Data System (ADS)

    Feng, Jinglang; Noomen, Ron; Visser, Pieter; Yuan, Jianping

    2016-08-01

    The general orbital motion around a contact binary asteroid system is investigated in this study. System 1996 HW1 is explored in detail, as it is the mostly bifurcated asteroid known to date. The location of its equilibrium points (EPs) is obtained and their linear stability is studied. Families of Lyapunov, Halo and vertical periodic orbits (POs) in the vicinity of these EPs as well as their stability are found and examined, respectively. The influence of the relative size of each lobe and the shape of the ellipsoidal lobe and the rotation rate of the asteroid on the location and stability of the EPs are studied. Additionally, two families of equatorial orbits are obtained at a wide range of distances: from far away to nearby. Their stability is examined against the distance to the asteroid and the rotation rate of the asteroid, to uncover the influence of highly non-spherical gravitational field and the rotation of the asteroid on the orbital motion. Finally, resonant orbits in N commensurability with the rotation of the asteroid are found and their stability is discussed. The fast rotation of the asteroid has a stabilizing effect on the equatorial orbital motion.

  7. The Lockne - Målingen doublet impacts, the result of a binary asteroid from the 470 Ma Main Asteroid Belt event

    NASA Astrophysics Data System (ADS)

    Sturkell, E. C.; Ormo, J.; Alwmark, C.; Melosh, H., IV

    2015-12-01

    Approximately 470 million years ago one of the largest cosmic catastrophes occurred in our solar system since the accretion of the planets. A 200-km large asteroid was disrupted by a collision in the Main Asteroid Belt (MAB), which spawned fragments into Earth crossing orbits. This had tremendous consequences for the meteorite production and cratering rate during several millions of years following the event. The 7.5-km wide Lockne crater, central Sweden, is known to be a member of this family. The 600 m large Lockne asteroid was a binary and had a companion in space by a smaller 150 m satellite. The recent discovery of the nearby, 0.7-km diameter, synchronous Målingen crater suggests it to form a doublet impact structure together with the larger Lockne crater, and as we will show here, most likely by a binary, 'rubble pile' asteroid. Despite observational evidence that about 16% of the Near Earth Asteroids (NEA's) are binary, only a handful of the approximately 188 known craters on Earth have been suggested as potential doublets. The stratigraphic and geographic relationship with Lockne suggests the Lockne and Målingen craters to be the first described doublet impact structure by a binary asteroid into a marine-target setting. In addition, the precise dating of the Lockne-Målingen impact in relation to the MAB breakup event provides a hands-on reference for studies of the formation of binaries from asteroid breakup events.

  8. Compositional Investigation of Binary Near-Earth Asteroid 66063 (1998 RO1): A Potentially Undifferentiated Assemblage

    NASA Technical Reports Server (NTRS)

    Abell, P. A.; Gaffey, M. J.; Landis, R. R.; Jarvis, K. S.

    2005-01-01

    It is now thought that approximately 16% of all asteroids among the near-Earth population may be binary objects. Several independent lines of evidence, such as the presence of doublet craters on the Earth and Moon [1, 2], complex lightcurves of near-Earth objects exhibiting mutual events [3], and radar images of near-Earth asteroids revealing distinct primary and secondary objects, have supported this conclusion [4]. To date at least 23 near-Earth objects have been discovered as binary systems with expectations that many more have yet to be identified or recognized. Little is known about the physical characteristics of binary objects except that they seem to have fairly rapid rotation rates, generally have primaries in the approx. 1 km diameter range with smaller secondaries on the order of a few hundred meters, and apart from a few exceptions, are in synchronous orbits [4, 5]. Previously only two of these binary near-Earth asteroids (1998 ST27 and 2003 YT1) have been characterized in terms of detailed mineralogical investigations [6, 7]. Such investigations are required to fully understand the formation mechanisms of these binary objects and their possible source regions. In addition, detailed knowledge of these objects may play an important role for planning future spacecraft missions and for the development of impact mitigation strategies. The work presented here represents a continued effort to characterize this particular sub-group of the near- Earth asteroid population.

  9. Period Determination of Binary Asteroid Targets Observed at Hunters Hill Observatory: May-September 2009

    NASA Astrophysics Data System (ADS)

    Higgins, David; Oey, Julian; Pravec, Petr

    2011-01-01

    Lightcurves for seven confirmed or possible binary asteroids were obtained at the Hunters Hill Observatory (HHO) and Leura Observatory from 2009 May through 2010 September: 1453 Fennia, 2501 Lohja, 3076 Garbor, 4029 Bridges, 5325 Silver, 6244 Okamoto, and (6265) 1985 TW3.

  10. Near-Infrared Spectroscopy (0.8 to 2.5 μm) of Small Trojan Asteorids

    NASA Astrophysics Data System (ADS)

    Emery, Joshua P.; Stamper, Nicholas; Cartwright, Richard J.; Lucas, Michael P.

    2016-10-01

    Orbiting the Sun in Jupiter's stable Lagrange regions at 5.2 AU, the Jupiter Trojan asteroids are a large population of primitive bodies distinct from Main Belt asteroids. The Trojan swarms are dominated by bodies with low albedos and red spectral slopes throughout the visible and near-infrared (VNIR; 0.4 – 2.5 μm), characteristic of D and P spectral taxa that are relatively rare in the Main Belt. The absence of absorption band in reflectance spectra of large (D≥75 km) Trojans has enabled the compositions of these bodies to remain a mystery. Because they likely formed beyond the snow line in the solar nebula, it is widely hypothesized that the bulk composition of Trojans includes a large fraction (~50%) of H2O ice. Low densities of two large binary Trojans support this hypothesis. The low albedos and red spectral slopes are generally hypothesized to be due to the presence of complex organics, although no absorption features supporting this hypothesis have yet been detected. Two VNIR spectral groups exist within the Trojans; ~2/3 of large Trojans form a cluster with very red (D-type-like) spectral slopes, while the other ~1/3 cluster around less-red (P-type-like) slopes. Visible colors of smaller Trojans suggest that the ratio of red to less-red Trojans decreases with decreasing size, from which Wong and Brown (2015; AJ 150:174) suggest that the interiors of all Trojans are represented by the less-red spectral group. In order to further test the hypothesis that Trojans contain H2O ice and complex organics and to test the result from visible colors that the spectral group ratio changes with size, we have measured near-infrared (0.8 – 2.5 μm) spectra of 35 small (~35 to 75 km) Trojans from both swarms using the SpeX spectrograph at the NASA Infrared Telescope Facility (IRTF). We confirm that the two spectral groups persist to smaller sizes, and we still detect no absorption features that would be diagnostic of composition. Nevertheless, the spectrum of one

  11. Jovian Trojan Exploration and Deep Space Cruising Sciences by the Solar Power Sail

    NASA Astrophysics Data System (ADS)

    Yano, Hajime

    2012-07-01

    Jovian Trojan asteroids are as one of a few remaining final frontiers within our Solar System, which may hold fundamental clues of the Solar System formation and revolution. Their genesis is discussed by two competing hypotheses between the classic model and the more recent Nice model. The former suggests that Trojan asteroids are mainly survivors of building blocks of the Jupiter system, while the latter claims that they must be intruders from outer regions after the planetary migration of gas planets settled. In previous years, scientific investigations of these dark, distant asteroid reservoirs were largely depended upon ground observations by large optical and spectroscopic telescopes, while few D-type asteroid analog meteorites were collected on the earth with an exception of Tagish Lake meteorites. However, thanks to recent development of observational technologies such as adaptive optics, statistical studies of asteroids in Jovian L4 and L5 regions have been made possible and raised new questions about their compositions far beyond the current snow line and internal structures implied by binary system measurements. This presentation discusses major scientific objectives of an exploration mission to Jovian Trojans for the first time in the history, its mission design and spacecraft system using solar power sail, a hybrid propulsion system of electric propulsion and photon sail, which inherited from the IKAROS deep space solar sail spacecraft, together with major engineering challenges, in-situ observation instruments and operational options.

  12. Hektor - Nature and origin of a binary asteroid

    NASA Technical Reports Server (NTRS)

    Weidenschilling, S. J.

    1980-01-01

    It is argued that the elongated single body model (Dunlap and Gehrels, 1969) which reproduces the rotational light curve of 624 Hektor is unstable with respect to binary fission. It is shown that a contact binary model with ellipsoidal components of equilibrium shape matches the observed amplitude. Hektor's bulk density is inferred to be about 2.5 g/cu cm.

  13. Population trends of binary near-Earth asteroids based on radar and lightcurves observations

    NASA Astrophysics Data System (ADS)

    Brozovic, Marina; Benner, Lance A. M.; Naidu, Shantanu P.; Taylor, Patrick A.; Busch, Michael W.; Margot, Jean-Luc; Nolan, Michael C.; Howell, Ellen S.; Springmann, Alessondra; Giorgini, Jon D.; Shepard, Michael K.; Magri, Christopher; Richardson, James E.; Rivera-Valentin, Edgard G.; Rodriguez-Ford, Linda A.; Zambrano Marin, Luisa Fernanda

    2016-10-01

    The Arecibo and Goldstone planetary radars are invaluable instruments for the discovery and characterization of binary and triple asteroids in the near-Earth asteroid (NEA) population. To date, 41 out of 56 known binaries and triples (~73% of the objects) have been discovered by radar and 49 of these multiple systems have been detected by radar. Their absolute magnitudes range from 12.4 for (1866) Sisyphus to 22.6 for 2015 TD144 and have a mean and rms dispersion of 18.1+-2.0. There is a pronounced decrease in the abundance of binaries for absolute magnitudes H>20. One of the smallest binaries, 1994 CJ1, with an absolute magnitude H=21.4, is also the most accessible binary for a spacecraft rendezvous. Among 365 NEAs with H<22 (corresponding to diameters larger than ~ 140 m) detected by radar since 1999, ~13% have at least one companion. Two triple systems are known, (15391) 2001 SN263 and (136617) 1994 CC, but this is probably an underestimate due to low signal to noise ratios (SNRs) for many of the binary radar detections. Taxonomic classes have been reported for 41 out of 56 currently known multiple systems and some trends are starting to emerge: at least 50% of multiple asteroid systems are S, Sq, Q, or Sk, and at least 20% are optically dark (C, B, P, or U). Thirteen V-class NEAs have been observed by radar and six of them are binaries. Curiously, a comparable number of E-class objects have been detected by radar, but none is known to be a binary.

  14. A Newborn Asteroid Family of Likely Rotational Origin Harboring a Doubly-Synchronous Binary

    NASA Astrophysics Data System (ADS)

    Drahus, Michal; Waniak, Waclaw

    2016-10-01

    From the total number of about twenty active asteroids identified to date, one of the most intriguing is P/2012 F5. The 2-km sized object has a short rotation period of 3.24 hr – the shortest known among main-belt active asteroids and comets – and is trailed by several fragments recently separated from the main nucleus (Drahus et al. 2015, ApJL 802, L8). Our extensive observations with Hubble in late 2015 and early 2016 have revealed that the fragments are real and stable "baby asteroids", still cocooned in their birth dust trail. Consequently, P/2012 F5 is the first known asteroid family forming in the present-day epoch. Given the rapid spin of the main nucleus, the system is also the best candidate for the first "rotational" asteroid family originating from rotational fission (as opposed to the long-known "collisional" families), extending the recently identified class of asteroid pairs (Pravec et al. 2010, Nature 466, 1085). Furthermore, the HST data allowed us to measure a light curve of the brightest fragment of P/2012 F5, several magnitudes fainter than the main nucleus. The light curve has all the characteristics of a close binary with significantly elongated, roughly equal sized components, having equal rotation and orbital periods of about 9 hr. The existence of a doubly-synchronous binary in an ultra-young asteroid family is seemingly inconsistent with the established "slow" binary formation path, in which YORP torques first lead to rotational fission and then tides lead to synchronization (Jacobson & Scheeres 2011, Icarus 214, 161). Instead, we believe that the object fissioned while orbiting the main nucleus and drawing its angular momentum, and was subsequently ejected from the system as a finished doubly-synchronous binary. This scenario is consistent with computer simulations in that the timescales for secondary fission and ejection from the system are indeed very short (Jacobson & Scheeres 2011, Icarus 214, 161). But the empirical evidence that

  15. A Jovian Trojan-Satellite Population Exchange

    NASA Astrophysics Data System (ADS)

    Stenborg, T. N.

    2003-07-01

    In Special Session 1, Recent Progress in Planetary Exploration, Monash University's Andrew Prentice discusses the possible origin of Jovian satellite Amalthea as a captured Trojan asteroid. Galileo spacecraft data gives a low bulk density (~1 g/cc) for Amalthea, more consistent with a captured minor body, rather than one formed in-situ. Its 83 km radius is within the size range of the known Jovian Trojans, less than that of Trojan 624 Hektor, for example.

  16. Libration-eccentricity evolution of expansive binary asteroids in the presence of tidal dissipation

    NASA Astrophysics Data System (ADS)

    McMahon, J.

    2014-07-01

    Singly-synchronous binary-asteroid systems have several evolutionary end-states, which depend heavily on the BYORP effect [1,2]. If BYORP is contractive, the primary and secondary could re-impact to form a contact binary, or they could end in a tidal-BYORP equilibrium [3]. Alternatively, if BYORP is expansive, they binary system could evolve to a wide asynchronous binary system [4,5], or the system could expand all the way to the Hill radius and form a heliocentric pair [3,6]. The distinction between these two expansive outcomes depends on whether the secondary asteroid stays synchronized, which keeps the BYORP effect active and the orbit expanding. The early analysis of the expansive case [1,2] showed that BYORP will act to maintain a near-circular binary orbit as the semi-major axis increases, however this was based on the assumption that the secondary is tidally locked at all distances. In reality, the secondary will be librating around the tidally locked orientation to some degree, and this libration will grow as the orbit expands. The libration also causes variations in the osculating binary orbit eccentricity due to the elongation of the secondary body. This coupling is key to determining the fate of the expanding system [7]. If the eccentricity grows large enough, the secondary will begin circulating and BYORP will be shut off; conversely, if the eccentricity is bound to small enough values the libration will also be bounded and thus the system will be free to keep expanding. As the system expands the eccentricity variations will shrink as the gravitational perturbations from the elongated secondary fall off. Making matters more complicated is the fact that as the orbit grows, the 3rd body perturbations from the Sun can have a larger effect on the binary orbit. This combination of coupled dynamics and perturbations whose magnitude varies greatly over the range of binary orbit semi-major axes requires exploration through high-fidelity numerical simulation. In

  17. The Effect of Shape Model Uncertainty on the Geophysical Predictions of Binary Asteroids

    NASA Astrophysics Data System (ADS)

    McMahon, Jay W.; Scheeres, Daniel

    2014-11-01

    Recent work by Jacobson and Scheeres (ApJ Vol. 736, L19) have shown that for a binary asteroid system in and equilibrium between tides and the binary YORP effect, the ratio Q/k can be determined, where Q is the tidal dissipation number and k is the tidal Love number. In their work, the value for B (the binary YORP coefficient) was that computed by McMahon and Scheeres (Icarus Vol. 209, pp 494-509, 2010) for binary asteroid 1999 KW4. Using this value, it was shown that the geophysical parameters Q/k can be estimated. Furthermore, we can similarly compute μQ based on the relationship between μ and k (where μ is the rigidity parameter), as discussed by Scheirich et al (ACM, Niigata, Japan, 2012, No. 1667, id.6123). These geophysical predictions, however, depend directly on the value of the binary YORP coefficient used, which is uncertain due to the limited shape model accuracy.In this study, we analyze the effect of shape model uncertainty on the predictions of Q/k and μQ. The 1999 KW4 secondary shape model is stochastically perturbed based on the radar observation accuracy (Ostro et al, Science Vol. 314, pp 1276-1280, 2006). Furthermore the detail of the topography is varied by adding more vertices to create a higher resolution shape model. For each newly perturbed shape model, the binary YORP coefficient is computed using our most advanced modeling software, and is used to derive new values for the geophysical parameter relationships. Furthermore we compute the B for a variety of known asteroid shape models as investigated by McMahon and Scheeres (44th AAS DPS, Reno, NV, 2012. Abstract No. 105.08). The results give effective error bounds on the Q/k (and derived μQ) predictions based on the shape model uncertainties.

  18. Near-Earth Asteroid 2005 CR37: Radar Images and Photometry of a Candidate Contact Binary

    NASA Technical Reports Server (NTRS)

    Benner, Lance A. M.; Nolan, Michael C.; Ostro, Steven J.; Giorgini, Jon D.; Pray, Donald P.; Harris, Alan W.; Magri, Christopher; Margot, Jean-Luc

    2006-01-01

    Arecibo (2380 MHz, 13 cm) radar observations of 2005 CR37 provide detailed images of a candidate contact binary: a 1.8-km-long, extremely bifurcated object. Although the asteroid's two lobes are round, there are regions of modest topographic relief, such as an elevated, 200-m-wide facet, that suggest that the lobes are geologically more complex than either coherent fragments or homogeneous rubble piles. Since January 1999, about 9% of NEAs larger than approx.200 m imaged by radar can be described as candidate contact binaries.

  19. Periodic orbits in the doubly synchronous binary asteroid systems and their applications in space missions

    NASA Astrophysics Data System (ADS)

    Shang, Haibin; Wu, Xiaoyu; Cui, Pingyuan

    2015-01-01

    This paper investigates the periodic motion of a particle in the doubly synchronous binary asteroid systems. Two typical doubly synchronous systems, 809 Lundia and 3169 Ostro, are discussed in detail. Under the Roche figure assumption, the two bodies of doubly synchronous system can be modeled as two triaxial ellipsoids. The Ivory's theorem is used to derive the gravitational potential of the system. Then, a global numerical method, which combines grid searching and differential correction, is developed for systematically searching periodic orbits in the doubly synchronous systems. A total of 30 and 28 families of periodic orbits around Lundia and Ostro are found, respectively. Furthermore, on the basis of the analysis of morphology, stabilities and invariant manifolds, the potential applications of these periodic orbit families are studied. Several quasi-circular orbit families with low instability index are found to be suitable for the observation of the two typical binary systems. The invariant manifolds of some periodic orbits near the equilibrium points can provide the fuel-free trajectories to achieve the ballistic landing to the surface of the asteroids and transfer between the binary asteroids.

  20. Shapes of binary asteroid primaries from photometric observations

    NASA Astrophysics Data System (ADS)

    Scheirich, Peter

    2016-10-01

    I will present results from a method which combine lightcurve inversion for single bodies and the method for inversion of lightcurves of occulting/eclipsing binary systems. A code developed by M. Kaasalainen and J. Durech for inversion of lightcurves of single bodies is adapted to fit our purposes. The original code uses a slightly elongated ellipsoid as an initial shape for optimization. We substituted this ellipsoid with a variety of shapes using Gaussian random spheres. This allowed the optimization algorithm to iterate to a range of final shapes.For each binary system, the short-period (rotational) component of its lightcurve is inverted using this code and a set of possible shapes of the primary are obtained. In the next step these shape models of the primary are, one by one, incorporated into the full model of the binary system and complete photometric data including the mutual events are fitted. Comparing synthetic lightcurves of the best-fit solutions with the observed data enables another narrowing of the selection of the possible shapes of the primary. This process is based on the times of phases of mutual events occurring on different geometries (i.e. the secondary passing in front of/behind the primary not only equator-on).We will also test a hypothesis that most of the primaries of the binary systems are similar in shape to each other. A figure resembling the shape of the primary of 1999 KW4, i.e., the top-shaped object with an equatorial ridge, will be used for the primary's shape. Its main characteristics – a polar flattening and width and height of the equatorial ridge, will be used as independent parameters. A variety of the shapes generated by a combination of these parameters will be used as an initial shapes for the optimization using the code described above.The work is supported by the Grant Agency of the Czech Republic, Grant 15-07193S.

  1. Asteroides

    NASA Video Gallery

    Los asteroides son más que una roca metálica que orbita alrededor del sol. Al igual que la Tierra, es posible que Ceres, el asteroide más grande del sistema solar, tenga casquetes polares. Únete a ...

  2. On the Possibility of Habitable Trojan Planets in Binary Star Systems.

    PubMed

    Schwarz, Richard; Funk, Barbara; Bazsó, Ákos

    2015-12-01

    Approximately 60% of all stars in the solar neighbourhood (up to 80% in our Milky Way) are members of binary or multiple star systems. This fact led to the speculations that many more planets may exist in binary systems than are currently known. To estimate the habitability of exoplanetary systems, we have to define the so-called habitable zone (HZ). The HZ is defined as a region around a star where a planet would receive enough radiation to maintain liquid water on its surface and to be able to build a stable atmosphere. We search for new dynamical configurations-where planets may stay in stable orbits-to increase the probability to find a planet like the Earth.

  3. On the Possibility of Habitable Trojan Planets in Binary Star Systems.

    PubMed

    Schwarz, Richard; Funk, Barbara; Bazsó, Ákos

    2015-12-01

    Approximately 60% of all stars in the solar neighbourhood (up to 80% in our Milky Way) are members of binary or multiple star systems. This fact led to the speculations that many more planets may exist in binary systems than are currently known. To estimate the habitability of exoplanetary systems, we have to define the so-called habitable zone (HZ). The HZ is defined as a region around a star where a planet would receive enough radiation to maintain liquid water on its surface and to be able to build a stable atmosphere. We search for new dynamical configurations-where planets may stay in stable orbits-to increase the probability to find a planet like the Earth. PMID:26113154

  4. New observations and new models of spin-orbit coupling in binary asteroids

    NASA Astrophysics Data System (ADS)

    Margot, Jean-Luc; Naidu, Shantanu

    2015-08-01

    The YORP-induced rotational fission hypothesis is the leading candidate for explaining the formation of binaries, triples, and pairs among small (<20 km) asteroids (e.g., Margot et al, Asteroids IV, subm., 2015). Various evolutionary paths following rotational fission have been suggested, but many important questions remain about the evolutionary mechanisms and timescales. We test hypotheses about the evolution of binary asteroids by obtaining precise descriptions of the orbits and components of binary systems with radar and by examining the system dynamics with detailed numerical simulations. Predictions for component spin states and orbital precession rates can then be compared to observables in our data sets or in other data sets to elucidate the states of various systems and their likely evolutionary paths.Accurate simulations require knowledge of the masses, shapes, and spin states of individual binary components. Because radar observations can provide exquisite data sets spanning days with spatial resolutions at the decameter level, we can invert for the component shapes and measure spin states. We can also solve for the mutual orbit by fitting the observed separations between components. In addition, the superb (10e-7--10e-8) fractional uncertainties in range allow us to measure the reflex motions directly, allowing masses of individual components to be determined.We use recently published observations of the binary 2000 DP107 (Naidu et al. AJ, subm., 2015) and that of other systems to simulate the dynamics of components in well-characterized binary systems (Naidu and Margot, AJ 149, 80, 2015). We model the coupled spin and orbital motions of two rigid, ellipsoidal bodies under the influence of their mutual gravitational potential. We use surface of section plots to map the possible spin configurations of the satellites. For asynchronous satellites, the analysis reveals large regions of phase space where the spin state of the satellite is chaotic. The

  5. Primary Surface Particle Motion as a Mechanism for YORP-Driven Binary Asteroid Evolution

    NASA Astrophysics Data System (ADS)

    Fahnestock, Eugene G.; Scheeres, D. J.

    2008-09-01

    Within the largest class of binary asteroid systems -- asynchronous binaries typified by 1999 KW4 -- we hypothesize continued YORP spin-up of the rapidly rotating primary leads to recurring episodic lofting motion of primary equator regolith. We theorize this is a mechanism for transporting YORP-injected angular momentum from primary spin into the mutual orbit. This both enables binary primaries to continue to spin at near surface fission rates and produces continued orbit expansion on time scales several times faster than expansion predicted by tidal dissipation alone. This is distinct from the Binary Yorp (BYORP) phenomenon, not studied in this work but to be added to it later. We evaluate our hypotheses using a combination of techniques for an example binary system. First high-fidelity dynamic simulation of surface-originating particles in the full-detail gravity field of the binary components, themselves propagated according to the full two body problem, gives particle final disposition (return impact, transfer impact, escape). Trajectory end states found for regolith lofted at different initial primary spin rates and relative poses are collected into probability matrices, allowing probabilistic propagation of surface particles for long durations at low computational cost. We track changes to mass, inertia dyad, rotation state, and centroid position and velocity for each component in response to this mapped particle motion. This allows tracking of primary, secondary, and mutual orbit angular momenta over time, clearly demonstrating the angular momentum transfer mechanism and validating our hypotheses. We present current orbit expansion rates and estimated orbit size doubling times consistent with this mechanism, for a few binary systems. We also discuss ramifications of this type of rapid binary evolution towards separation, including the frequency with which "divorced binaries" on similar heliocentric orbits are produced, formation of triple systems such as

  6. The Asteroid Redirect Mission (ARM): Exploration of a Former Binary NEA?

    NASA Technical Reports Server (NTRS)

    Abell, P. A.; Mazanek, D. D.; Reeves, D. M.; Chodas, P. W.; Gates, M. M.; Johnson, L. N.; Ticker, R. L.

    2016-01-01

    The National Aeronautics and Space Administration (NASA) is developing the Asteroid Redirect Mission (ARM) as a capability demonstration for future human exploration, including use of high-power solar electric propulsion, which allows for the efficient movement of large masses through deep space. The ARM will also demonstrate the capability to conduct proximity operations with natural space objects and crewed operations beyond the security of quick Earth return. The Asteroid Redirect Robotic Mission (ARRM), currently in formulation, will visit a large near-Earth asteroid (NEA), collect a multi-ton boulder from its surface, conduct a demonstration of a slow push planetary defense technique, and redirect the multi-ton boulder into a stable orbit around the Moon. Once returned to cislunar space in the mid-2020s, astronauts aboard an Orion spacecraft will dock with the robotic vehicle to explore the boulder and return samples to Earth. The ARM is part of NASA's plan to advance technologies, capabilities, and spaceflight experience needed for a human mission to the Martian system in the 2030s. The ARM and subsequent availability of the asteroidal material in cis-lunar space, provide significant opportunities to advance our knowledge of small bodies in the synergistic areas of science, planetary defense, and in-situ resource utilization (ISRU). The current reference target for the ARM is NEA (341843) 2008 EV5, which may have been the primary body of a former binary system (Busch et al., 2011; Tardivel et al., 2016). The ARRM will perform several close proximity operations to investigate the NEA and map its surface. A detailed investigation of this object may allow a better understanding of binary NEA physical characteristics and the possible outcomes for their evolution. An overview of the ARM robotic and crewed segments, including mission operations, and a discussion of potential opportunities for participation with the ARM will be provided in this presentation.

  7. Radar-Derived Shape Model of Near-Earth Binary Asteroid System (285263) 1998 QE2

    NASA Astrophysics Data System (ADS)

    Springmann, Alessondra; Taylor, Patrick A.; Nolan, Michael C.; Howell, Ellen S.; Brozovi?, Marina; Benner, Lance A.; Giorgini, Jon D.; Busch, Michael W.; Margot, Jean-Luc; Lee, Clement; Jao, Joseph S.; Lauretta, Dante S.

    2014-11-01

    We report on shape modeling of binary asteroid 1998 QE2, a 3.2-km asteroid with a 800-m moon. We observed this asteroid with both Arecibo Observatory planetary radar (2380 MHz, 12.6 cm) and Goldstone Solar System Radar (8560 MHz, 3.5 cm) between May 31-Jun 9, 2013. The close approach on May 31, 2013 (0.039 au) presented an outstanding opportunity for radar delay-Doppler imaging with resolutions as fine as 7.5 m of both objects. The extensive radar dataset was used for shape modeling of both components. Our SHAPE 3D modeling software (Hudson, 1993 and Magri et al., 2007) uses a constrained, weighted least-squares minimization procedure to invert radar delay-Doppler images.The rotation rate of the primary, 4.749 ± 0.002 h, was well constrained from optical lightcurves (P. Pravec, pers. comm.) and rotates prograde as determined from radar data. The primary is roughly spheroidal, showing prominent concavities and surface features, with effective diameter 3.2 ± 0.3 km.The secondary is irregularly shaped, with an effective diameter of 800 ± 80 m and significant elongation. The radar data suggest it is tidally locked, with an orbital period of 31.31 ± 0.01 h hours and a semi-major orbital axis of 6.2 ± 0.1 km. The orbit is approximately circular (e < 0.01), which is typical of most near-Earth asteroid binary system orbits. We estimate a preliminary density for the primary of 0.7 ± 0.2 g/cm^3. The low density is consistent with a "rubble pile" structure.

  8. Trajectory exploration within asynchronous binary asteroid systems using refined Lagrangian coherent structures

    NASA Astrophysics Data System (ADS)

    Shang, Haibin; Wu, Xiaoyu; Cui, Pingyuan

    2016-09-01

    Ground observations have found that asynchronous systems constitute most of the population of the near-Earth binary asteroids. This paper concerns the trajectory of a particle in the asynchronous system which is systematically described using periodic ellipsoidal and spherical body models. Due to the non-autonomous characteristics of the asynchronous system, Lagrangian coherent structures (LCS) are employed to identify the various dynamical behaviors. To enhance the accuracy of LCS, a robust LCS finding algorithm is developed incorporating hierarchical grid refinement, one-dimensional search and variational theory verification. In this way, the intricate dynamical transport boundaries are detected efficiently. These boundaries indicate that a total of 15 types of trajectories exist near asynchronous binary asteroids. According to their Kepler energy variations, these trajectories can be grouped into four basic categories, i.e., transitory, escape, impact and flyby trajectories. Furthermore, the influence of the ellipsoid's spin period on the dynamical behavior is discussed in the context of the change of dynamical regions. We found that the transitory and impact motions occur easily in the synchronous-like binary systems, in which the rotation period of the ellipsoid is nearly equal to that of the mutual orbit. Meanwhile, the results confirm a positive correlation between the spinning rate of the ellipsoid and the probability of the escape and flyby trajectories. The LCS also reveal a marked increase in trajectory diversity after a larger initial energy is selected.

  9. Geodynamic stability of the primary in the binary asteroid system 65803 Didymos

    NASA Astrophysics Data System (ADS)

    Barnouin, Olivier S.; Maurel, Clara; Richardson, Derek C.; Ballouz, Ronald-Louis; Schwartz, Stephen; Michel, Patrick

    2015-11-01

    The moon of the near-Earth binary asteroid 65803 Didymos is the target of the Asteroid Impact and Deflection Assessment (AIDA) mission. This mission is a joint concept between NASA and ESA to investigate the effectiveness of a kinetic impactor in deflecting an asteroid. The mission is composed of two components: the NASA-led Double Asteroid Redirect Test (DART) that will impact the Didymos moon, and the ESA-led Asteroid Impact Monitoring (AIM) mission that will characterize the Didymos system. In order to provide AIDA constraints on the physical character of the both objects in this binary system, we undertook preliminary numerical investigations to evaluate the stability of the shape of the primary using its rapid 2.26 h rotation. We modeled the primary as a rubble pile. Each model consisted of thousands of uniform rigid spheres collapsed together under their own gravity to form a spherical pile that was then carved to match the current radar-derived shape model of the primary, as well as other comparable shapes (e.g. asteroid 1999 KW4, spheres) that were scaled to match best estimates of the size of Didymos. Each model was given a starting rotation period of 6 h with the spin axis aligned to the pole. At each timestep the spin rate was increased by a small amount so that after about 1 million timesteps the spin would match the observed rotation of 2.26 h. We tested a range of bulk densities spanning the current observational uncertainty (mean 2.4 g/cc) using "gravel"-like material parameters that provide significant resistance to sliding and rolling. We find that at the upper range of the density uncertainty it is possible for Didymos to hold its shape and not lose mass at its nominal rotation period, without the need for cohesive forces. At lower densities or with smoother particles, significant shape change occurs and mass loss is possible. We conclude that based on the radar shape available at the time of this writing, Didymos is marginally stable as a rubble

  10. Stable Orbits in the Didymos Binary Asteroid System - Useful Platforms for Exploration

    NASA Astrophysics Data System (ADS)

    Damme, Friedrich; Hussmann, Hauke; Wickhusen, Kai; Enrico, Mai; Oberst, Jürgen

    2016-04-01

    We have analyzed particle motion in binary asteroid systems to search for stable orbits. In particular, we studied the motion of particles near the asteroid 1996 GT (Didymos), proposed as a target for the AIDA mission. The combined gravity fields of the odd-shaped rotating objects moving about each other are complex. In addition, orbiting spacecraft or dust particles are affected by radiation pressure, possibly exceeding the faint gravitational forces. For the numerical integrations, we adopt parameters for size, shape, and rotation from telescopic observations. To simulate the effect of radiation pressure during a spacecraft mission, we apply a spacecraft wing-box shape model. Integrations were carried out beginning in near-circular orbits over 11 days, during which the motion of the particles were examined. Most orbits are unstable with particles escaping quickly or colliding with the asteroid bodies. However, with carefully chosen initial positions, we found stable motion (in the orbiting plane of the secondary) associated with the Lagrangian points (L4 and L5), in addition to horseshoe orbits, where particles move from one of the Lagrangian point to the other. Finally, we examined orbits in 1:2 resonances with the motion of the orbital period of the secondary. Stable conditions depend strongly on season caused by the inclination of the mutual orbit plane with respect to Didymos solar orbit. At larger distance from the asteroid pair, we find the well-known terminator orbits where gravitational attraction is balanced against radiation pressure. Stable orbits and long motion arcs are useful for long tracking runs by radio or Laser instruments and are well-suited for modelling of the ephemerides of the asteroid pair and gravity field mapping. Furthermore, these orbits may be useful as observing posts or as platforms for approach. These orbits may also represent traps for dust particles, an opportunity for dust collection - or possibly a hazard to spacecraft

  11. Tidal Evolution of Asteroidal Binaries. Ruled by Viscosity. Ignorant of Rigidity.

    NASA Astrophysics Data System (ADS)

    Efroimsky, Michael

    2015-10-01

    This is a pilot paper serving as a launching pad for study of orbital and spin evolution of binary asteroids. The rate of tidal evolution of asteroidal binaries is defined by the dynamical Love numbers kl divided by quality factors Q. Common in the literature is the (oftentimes illegitimate) approximation of the dynamical Love numbers with their static counterparts. Since the static Love numbers are, approximately, proportional to the inverse rigidity, this renders a popular fallacy that the tidal evolution rate is determined by the product of the rigidity by the quality factor: {k}l/Q\\propto 1/(μ Q). In reality, the dynamical Love numbers depend on the tidal frequency and all rheological parameters of the tidally perturbed body (not just rigidity). We demonstrate that in asteroidal binaries the rigidity of their components plays virtually no role in tidal friction and tidal lagging, and thereby has almost no influence on the intensity of tidal interactions (tidal torques, tidal dissipation, tidally induced changes of the orbit). A key quantity that overwhelmingly determines the tidal evolution is a product of the effective viscosity η by the tidal frequency χ . The functional form of the torque’s dependence on this product depends on who wins in the competition between viscosity and self-gravitation. Hence a quantitative criterion, to distinguish between two regimes. For higher values of η χ , we get {k}l/Q\\propto 1/(η χ ), {while} for lower values we obtain {k}l/Q\\propto η χ . Our study rests on an assumption that asteroids can be treated as Maxwell bodies. Applicable to rigid rocks at low frequencies, this approximation is used here also for rubble piles, due to the lack of a better model. In the future, as we learn more about mechanics of granular mixtures in a weak gravity field, we may have to amend the tidal theory with other rheological parameters, ones that do not show up in the description of viscoelastic bodies. This line of study provides

  12. Lightcurve Analysis of NEA (154244) 2002 KL6: A Potential New Binary Asteroid

    NASA Astrophysics Data System (ADS)

    Warner, Brian D.; Benishek, Vladimir; Ferrero, Andrea; Skiff, Brian A.

    2016-10-01

    Analysis of CCD photometric observations of near-Earth asteroid (154244) 2002 KL6 indicate that it may be a binary system. The presumed primary has a synodic rotation period of 4.60869 ± 0.00005 h and lightcurve amplitude of 0.65 ± 0.03 mag. The presumed satellite has an orbital period of 24.05 ± 0.02 h and maximum lightcurve amplitude of 0.07 mag. The secondary lightcurve showed no mutual events and seems to indicate that the satellite's rotation is tidally locked to its orbital period.

  13. Analysis of GSC 2475-1587 and GSC 841-277: Two Eclipsing Binary Stars Found During Asteroid Lightcurve Observations

    NASA Astrophysics Data System (ADS)

    Stephens, R. D.; Warner, B. D.

    2006-05-01

    When observing asteroids we select from two to five comparison stars for differential photometry, taking the average value of the comparisons for the single value to be subtracted from the value for the asteroid. As a check, the raw data of each comparison star are plotted as is the difference between any single comparison and the average of the remaining stars in the set. On more than one occasion, we have found that at least one of the comparisons was variable. In two instances, we took time away from our asteroid lightcurve work to determine the period of the two binaries and attempted to model the system using David Bradstreet's Binary Maker 3. Unfortunately, neither binary showed a total eclipse. Therefore, our results are not conclusive and present only one of many possibilities.

  14. Radar Shape Modeling of Binary Near-Earth Asteroid 2000 CO101

    NASA Astrophysics Data System (ADS)

    Jimenez, Nicholas; Howell, E. S.; Nolan, M. C.; Taylor, P. A.; Benner, L. A. M.; Brozovic, M.; Giorgini, J. D.; Vervack, R. J.; Fernandez, Y. R.; Mueller, M.; Margot, J.; Shepard, M. K.

    2010-10-01

    We observed the near-Earth binary system 2000 CO101 in 2009 September using the Goldstone and Arecibo radar systems and inverted these images to create shape models of the primary. Asteroid 2000 CO101 was discovered to be a binary system from Arecibo images taken on 2009 September 26 (Taylor et al. 2009). Analyzing the images, we were able to determine approximate values for the radius of the primary (310 m) and the radius of the secondary (22 m). The maximum observed range separation was approximately 610 m. The images show it to appear spherical. Shape modeling of the primary of this system will constrain the asteroid's size, spin rate, and pole orientation. Because other NEA binary systems have exhibited shapes similar to that of 1999 KW4 (Ostro et al. 2006, Scheeres et al. 2006), we initially adopted this shape for 2000 CO101 and have allowed only the linear scales along the three principal axes to adjust to the radar data. This enables us to constrain the volume. With some constraints on the orbit of the satellite we will place limits on the density of the primary. The near-infrared spectrum of 2000 CO101 was measured on 2009 September 21 and 2010 March 13. The 0.8-2.5 micron spectrum was measured on both dates, and shows a featureless, red-sloped spectrum. On September 21 we also measured the thermal emission between 2-4 microns to determine the albedo and thermal properties. Both standard thermal models and thermophysical models have been applied to these data. The albedo we derive from the thermal modeling must also be consistent with the radar size. Characterization of this unusual NEA binary system will be presented.

  15. Dynamics of ejecta from the binary asteroid Didymos, the target of the AIDA mission

    NASA Astrophysics Data System (ADS)

    Michel, Patrick; Yu, Yang; Schwartz, Stephen; Naidu, Shantanu; Benner, Lance

    2016-04-01

    The AIDA space mission, a collaborative effort between ESA and NASA, aims to characterize the near-Earth asteroid binary (65803) Didymos and to perform a kinetic impactor demonstration on the small moon of the binary system. Our study presents a multi-scale dynamical model of the ejecta cloud produced by a hypervelocity impact, which enables us to compute the ejecta properties at different spatial and time scales. This model is applied to the impact into the small moon of Didymos on October 2022 as considered by the AIDA mission. We model the process by including as much practical information as possible, e.g., the gravitational environment influenced by the non-spherical shapes of the bodies (based on the observed shape of the primary), the solar tides, and the solar radiation pressure. Our simulations show where and for how long the ejecta cloud evolves with time for the considered ejecta initial conditions. This information is used to assess the potential hazard to the ESA Asteroid Impact Mission (AIM) observing spacecraft and to determine the safest positions. This study is performed with support of the European Space Agency and in the framework of the NEOShield-2 project that has received funding from the European Union's Horizon 2020 research and innovation program under grant agreement No 640351.

  16. Dynamical model of binary asteroid systems through patched three-body problems

    NASA Astrophysics Data System (ADS)

    Ferrari, Fabio; Lavagna, Michèle; Howell, Kathleen C.

    2016-08-01

    The paper presents a strategy for trajectory design in the proximity of a binary asteroid pair. A novel patched approach has been used to design trajectories in the binary system, which is modeled by means of two different three-body systems. The model introduces some degrees of freedom with respect to a classical two-body approach and it is intended to model to higher accuracy the peculiar dynamical properties of such irregular and low gravity field bodies, while keeping the advantages of having a full analytical formulation and low computational cost required. The neighborhood of the asteroid couple is split into two regions of influence where two different three-body problems describe the dynamics of the spacecraft. These regions have been identified by introducing the concept of surface of equivalence (SOE), a three-dimensional surface that serves as boundary between the regions of influence of each dynamical model. A case of study is presented, in terms of potential scenario that may benefit of such an approach in solving its mission analysis. Cost-effective solutions to land a vehicle on the surface of a low gravity body are selected by generating Poincaré maps on the SOE, seeking intersections between stable and unstable manifolds of the two patched three-body systems.

  17. PHYSICAL CHARACTERIZATION AND ORIGIN OF BINARY NEAR-EARTH ASTEROID (175706) 1996 FG{sub 3}

    SciTech Connect

    Walsh, Kevin J.; Delbo, Marco; Mueller, Michael; Binzel, Richard P.; DeMeo, Francesca E.

    2012-04-01

    The near-Earth asteroid (NEA) (175706) 1996 FG{sub 3} is a particularly interesting spacecraft target: a binary asteroid with a low-{Delta}v heliocentric orbit. The orbit of its satellite has provided valuable information about its mass density while its albedo and colors suggest it is primitive or part of the C-complex taxonomic grouping. We extend the physical characterization of this object with new observations of its emission at mid-infrared wavelengths and with near-infrared reflection spectroscopy. We derive an area-equivalent system diameter of 1.90 {+-} 0.28 km (corresponding to approximate component diameters of 1.83 km and 0.51 km, respectively) and a geometric albedo of 0.039 {+-} 0.012. (175706) 1996 FG{sub 3} was previously classified as a C-type asteroid, though the combined 0.4-2.5 {mu}m spectrum with thermal correction indicates classification as B-type; both are consistent with the low measured albedo. Dynamical studies show that (175706) 1996 FG{sub 3} most probably originated in the inner main asteroid belt. Recent work has suggested the inner Main Belt (142) Polana family as the possible origin of another low-{Delta}v B-type NEA, (101955) 1999 RQ{sub 36}. A similar origin for (175706) 1996 FG{sub 3} would require delivery by the overlapping Jupiter 7:2 and Mars 5:9 mean motion resonances rather than the {nu}{sub 6}, and we find this to be a low probability, but possible, origin.

  18. Physical Characterization and Origin of Binary Near-Earth Asteroid (175706) 1996 FG3

    NASA Astrophysics Data System (ADS)

    Walsh, Kevin J.; Delbo', Marco; Mueller, Michael; Binzel, Richard P.; DeMeo, Francesca E.

    2012-04-01

    The near-Earth asteroid (NEA) (175706) 1996 FG3 is a particularly interesting spacecraft target: a binary asteroid with a low-Δv heliocentric orbit. The orbit of its satellite has provided valuable information about its mass density while its albedo and colors suggest it is primitive or part of the C-complex taxonomic grouping. We extend the physical characterization of this object with new observations of its emission at mid-infrared wavelengths and with near-infrared reflection spectroscopy. We derive an area-equivalent system diameter of 1.90 ± 0.28 km (corresponding to approximate component diameters of 1.83 km and 0.51 km, respectively) and a geometric albedo of 0.039 ± 0.012. (175706) 1996 FG3 was previously classified as a C-type asteroid, though the combined 0.4-2.5 μm spectrum with thermal correction indicates classification as B-type; both are consistent with the low measured albedo. Dynamical studies show that (175706) 1996 FG3 most probably originated in the inner main asteroid belt. Recent work has suggested the inner Main Belt (142) Polana family as the possible origin of another low-Δv B-type NEA, (101955) 1999 RQ36. A similar origin for (175706) 1996 FG3 would require delivery by the overlapping Jupiter 7:2 and Mars 5:9 mean motion resonances rather than the ν6, and we find this to be a low probability, but possible, origin. Partially based on observations obtained at the European Southern Observatory (ESO, program ID 383.C-0179A). Observations were also obtained at the Infrared Telescope Facility, which is operated by the University of Hawaii under Cooperative Agreement No. NCC 5-538 with the National Aeronautics and Space Administration, Science Mission Directorate, Planetary Astronomy Program.

  19. Asteroid flux towards circumprimary habitable zones in binary star systems. II. Dynamics

    NASA Astrophysics Data System (ADS)

    Bancelin, D.; Pilat-Lohinger, E.; Bazsó, Á.

    2016-06-01

    Context. Secular and mean motion resonances (MMR) are effective perturbations for shaping planetary systems. In binary star systems, they play a key role during the early and late phases of planetary formation, as well as for the dynamical stability of a planetary system. Aims: In this study, we aim to correlate the presence of orbital resonances with the rate of icy asteroids crossing the habitable zone (HZ) from a circumprimary disk of planetesimals in various binary star systems. Methods: We modelled a belt of small bodies in the inner and outer regions, interior and exterior to the orbit of a gas giant planet, respectively. The planetesimals are equally placed around a primary G-type star and move under the gravitational influence of the two stars and the gas giant. We numerically integrated the system for 50 Myr, considering various parameters for the secondary star. Its stellar type varies from a M- to F-type; its semimajor axis is either 50 au or 100 au, and its eccentricity is either 0.1 or 0.3. For comparison, we also varied the gas giant's orbital and physical parameters. Results: Our simulations highlight that a disk of planetesimals will suffer from perturbations owing to a perturbed gas giant, mean motion, and secular resonances. We show that a secular resonance - with location and width varying according to the secondary star's characteristics - can exist in the icy asteroid belt region and overlap with MMRs, which have an impact on the dynamical lifetime of the disk. In addition, we point out that, in any case, the 2:1 MMR, the 5:3 MMR, and the secular resonance are powerful perturbations for the flux of icy asteroids towards the HZ and the transport of water therein.

  20. Radar Imaging of Binary Near-Earth Asteroid (357439) 2004 BL86

    NASA Astrophysics Data System (ADS)

    Benner, Lance AM; Brozovic, Marina; Giorgini, Jon D.; Jao, Joseph S.; Lee, Clement G.; Taylor, Patrick A.; Howell, Ellen S.; Busch, Michael W.; Ford, H. Alyson; Ghigo, Frank; Nolan, Michael C.; Slade, Martin A.; Lawrence, Kenneth J.; Richardson, James E.; Rivera-Valentin, Edgard G.; Rozek, Agata

    2015-08-01

    We report radar observations of near-Earth asteroid 2004 BL86 obtained during 2015 Jan. 26-31 at the 70 m and 34 m Goldstone facilities, Arecibo, Green Bank, and elements of the Very Long Baseline Array. 2004 BL86 approached within 0.0080 au (3.1 lunar distances) on Jan. 26, the closest known approach by any object with an absolute magnitude brighter than ~19 until 2027. Prior to the encounter, virtually nothing was known about its physical properties other than its absolute magnitude of 19, which suggested a diameter within a factor of two of 500 m. Due to its size and the extremely close approach, 2004 BL86 was a very strong radar target that provided an outstanding opportunity for radar imaging and physical characterization. The radar images confirmed photometric results reported by Pravec et al. (2015, CBET 4063) that 2004 BL86 is a binary system. This is the 43rd near-Earth asteroid binary detected by radar. Delay-Doppler images placed thousands of 3.75 m-resolution pixels on the object and reveal a rounded and oblate primary with an equatorial diameter of ~300 m, suggesting it is optically-bright, evidence for ridges, small-scale topography including boulders, and a large angular feature near one of the poles. A preliminary estimate for the diameter of the secondary is ~70 m. The images hint that the secondary’s rotation is synchronous with its orbital period. The observations also yielded the first detection of an asteroid with a new 80 kW C-band radar (7190 MHz, 4.2 cm) at the 34 m DSS-13 antenna at the Goldstone Deep Space Communications Complex. This new radar can achieve a range resolution up to 1.875 m/pixel that is twice as fine as the highest resolution previously achievable.

  1. Dynamics of possible Uranus Trojans

    NASA Astrophysics Data System (ADS)

    Bazsó, Ákos; Dvorak, Rudolf

    2011-06-01

    We conducted a dynamical survey to find the properties of - and influences on - the motion of hypothetical Trojan asteroids around Uranus. For low eccentric orbits, we integrated a set of more than 6000 Trojans with different initial semi-major axes and inclinations up to i = 60 deg. The general integration time was set to 100 Myr, some selected orbits were integrated for a time span covering the age of the Solar System. We found two regions at which a Trojan can remain in a low libration amplitude state for at least 100 Myr, one at low inclinations up to 6 deg, and the other at higher inclinations from 40 deg to around 50 deg. Using frequency analysis on the output of numerical integrations we identified several important secular resonances. Those secular resonances with Jupiter and Neptune affect the motion of the Uranus Trojans, and shape the stability region around the equilateral equilibrium points. Although there is a fast depletion of Trojans within 100 Myr, the two stable regions would support the long-time presence of Trojans.

  2. Dynamical Lifetimes of Mars Trojans

    NASA Astrophysics Data System (ADS)

    Scholl, H.; Marzari, F.; Tricarico, P.

    2004-05-01

    Several authors investigated within the last ten years the stability of known Mars Trojans. A maximum of five Trojans were quoted to librate around L5 and one around L4. Recent orbital data yield less Mars Trojans. According to our computations using orbital elements of Bowell's catalogue (march 2004), only three of the known asteroids, (5261) Eureka, 1998 VF31 and 2001 DH47 appear to librate around L5 over at least 1 Myr. Other previously quoted Mars Trojans are no more in the Trojan region, presumably due to an orbital improvement. We investigated the dynamical lifetime of the longest observed Trojan, Eureka, by two methods: i) by applying Laskar's frequency analysis and ii) by integrating the orbit of Eureka surrounded by a cloud of clones over several Gyrs. The Yarkovski effect is also taken into account in some integrations. The dynamical lifetime of Eureka is found to be of the order of 2-3 Gyrs. Spectroscopic and photometric results by Rivkin et al. (2003) suggest that Eureka is a highly differentiated kilometer-sized body. Its parent body was a much larger body. The physical properties of Eureka and its comparatively short dynamical lifetime rise the question for its origin.

  3. Coupled Spin and Orbital Dynamics of Binary Near-Earth Asteroids 2000 DP107 and 1991 VH

    NASA Astrophysics Data System (ADS)

    Naidu, Shantanu; Margot, J.

    2013-10-01

    Binaries form a significant fraction 15%) of the near-Earth asteroid (NEA) population. Various models suggest that they are evolving and that some of them might be in an intermediate stage towards the formation of binary pairs, contact binary NEAs, or triple NEAs. Binary NEAs are thought to evolve under the influence of gravitational and radiative forces such as YORP and binary YORP (e.g., Cuk and Burns, 2005). A wide variety of end-states may arise depending on the relative magnitudes of the forces, which are dictated by the component shapes, spins, and mutual orbit of the binary (e.g., Jacobson & Scheeres 2011, Fang & Margot 2012). Because the spins and mutual orbits of binary NEAs are tightly coupled to each other, understanding the spin-orbit interaction is key to modeling binary NEA evolution. This interaction can be studied using asteroid shape models (e.g., Scheeres et al. 2006, Fahnestock and Scheeres, 2006). We will present numerical simulations describing the spin-orbit states of two binary NEAs, 2000 DP107 and 1991 VH, as well as the consequences for the evolution of binary NEAs. Naidu et al. (2011) presented the radar-derived component shape models, masses, densities, spin states, and the mutual orbit of binary near-Earth asteroid 2000 DP107. The smaller component spins synchronously and may exhibit small amplitude (< 5 degree) librations. The mutual orbit pole and primary spin pole fits to the radar data suggest that they are inclined with respect to each other. Such an inclined orbit would precess due to the oblateness of the primary component. For 1991 VH, Naidu et al. (2012) were unable to fit a unique spin period to the elongated secondary using radar images and suggested that it might be in a chaotic spin state on the basis of theoretical considerations and numerical simulations. We will present improved simulations that include spin-orbit coupling.

  4. Radar observations and physical modeling of binary near-Earth asteroid (1862) Apollo

    NASA Astrophysics Data System (ADS)

    Ford, Thomas F.; Benner, Lance A.; Brozovic, Marina; Leford, Bruce; Nolan, Michael C.; Giorgini, Jon D.; Ostro, Steve J.; Margot, Jean-Luc

    2014-11-01

    Binary asteroid 1862 Apollo has an extensive observational history allowing many of its characteristics to be investigated. Apollo was one of the first objects to show evidence for the YORP effect (Kaasalainen et al. 2007, Nature 446, 420) and its mass has been estimated by detection of the Yarkovsky effect (Nugent et al. 2012, AJ 144, 60; Farnocchia et al. 2013, Icarus 224, 1). We observed Apollo at Arecibo and Goldstone from Oct. 29-Nov. 13, 2005, obtaining a series of echo power spectra and delay-Doppler images that achieved resolutions as high as 7.5 m/pixel. The Arecibo images show that Apollo is a binary system with a rounded primary that has two large protrusions about 120 deg apart in longitude. We used the Arecibo data and published lightcurves to estimate the primary's 3D shape. Our best fit has major axes of ~1.8x1.5x1.3 km and a volume of ~1.6 km^3. The protrusions have lengths of ~300 and 200 m, are on the primary's equator, and give Apollo a distinctly different appearance from the primaries with equatorial ridges seen with other binary near-Earth asteroids. We estimated the pole by starting with the Kaasalainen et al. spin vector of ecliptic (longitude, latitude)=(50 deg, -71 deg) +- 7 deg and letting it float. Our best fit has a pole within 11 deg of (longitude, latitude)=(71, -72). Convex models produced from inversion of lightcurves by Kaasalainen et al. and thermal infrared data by Rozitis et al. (2013, A&A 555, A20) are more oblate than our model, do not show protrusions, and have somewhat different pole directions. The Arecibo images reveal weak but persistent echoes from a satellite on Nov. 1 and 2 but cover only a fraction of its orbit. The images are insufficient to estimate the satellite's shape and yield a rough estimate for its long axis of 190 m. Preliminary fits give an orbital period of ~27.0-27.5 h and a semimajor axis of ~3.5-4.0 km, implying a mass of 2.8-3.9E12 kg and a bulk density of 1.7-2.4 g/cm^3. The density is consistent with

  5. A thick cloud of Neptune Trojans and their colors.

    PubMed

    Sheppard, Scott S; Trujillo, Chadwick A

    2006-07-28

    The dynamical and physical properties of asteroids offer one of the few constraints on the formation, evolution, and migration of the giant planets. Trojan asteroids share a planet's semimajor axis but lead or follow it by about 60 degrees near the two triangular Lagrangian points of gravitational equilibrium. Here we report the discovery of a high-inclination Neptune Trojan, 2005 TN(53). This discovery demonstrates that the Neptune Trojan population occupies a thick disk, which is indicative of "freeze-in" capture instead of in situ or collisional formation. The Neptune Trojans appear to have a population that is several times larger than the Jupiter Trojans. Our color measurements show that Neptune Trojans have statistically indistinguishable slightly red colors, which suggests that they had a common formation and evolutionary history and are distinct from the classical Kuiper Belt objects.

  6. A Thick Cloud of Neptune Trojans and Their Colors

    NASA Astrophysics Data System (ADS)

    Sheppard, Scott S.; Trujillo, Chadwick A.

    2006-07-01

    The dynamical and physical properties of asteroids offer one of the few constraints on the formation, evolution, and migration of the giant planets. Trojan asteroids share a planet's semimajor axis but lead or follow it by about 60° near the two triangular Lagrangian points of gravitational equilibrium. Here we report the discovery of a high-inclination Neptune Trojan, 2005 TN53. This discovery demonstrates that the Neptune Trojan population occupies a thick disk, which is indicative of ``freeze-in'' capture instead of in situ or collisional formation. The Neptune Trojans appear to have a population that is several times larger than the Jupiter Trojans. Our color measurements show that Neptune Trojans have statistically indistinguishable slightly red colors, which suggests that they had a common formation and evolutionary history and are distinct from the classical Kuiper Belt objects.

  7. A thick cloud of Neptune Trojans and their colors.

    PubMed

    Sheppard, Scott S; Trujillo, Chadwick A

    2006-07-28

    The dynamical and physical properties of asteroids offer one of the few constraints on the formation, evolution, and migration of the giant planets. Trojan asteroids share a planet's semimajor axis but lead or follow it by about 60 degrees near the two triangular Lagrangian points of gravitational equilibrium. Here we report the discovery of a high-inclination Neptune Trojan, 2005 TN(53). This discovery demonstrates that the Neptune Trojan population occupies a thick disk, which is indicative of "freeze-in" capture instead of in situ or collisional formation. The Neptune Trojans appear to have a population that is several times larger than the Jupiter Trojans. Our color measurements show that Neptune Trojans have statistically indistinguishable slightly red colors, which suggests that they had a common formation and evolutionary history and are distinct from the classical Kuiper Belt objects. PMID:16778021

  8. Shape model of the binary near-Earth asteroid (285263) 1998 QE_2

    NASA Astrophysics Data System (ADS)

    Springmann, A.; Taylor, P.; Nolan, M.; Howell, E.; Benner, L.; Brozović, M.; Giorgini, J.; Busch, M.; Margot, J.; Lee, C.; Gao, J.

    2014-07-01

    Binary systems comprise ˜1/6 of the near-Earth object population larger than 200 meters in diameter, providing important clues to asteroids' masses and densities. On May 31, 2013, the binary near-Earth-asteroid system (285263) 1998 QE_2 had a 0.04-au close approach to the Earth. We observed the binary system from May 30 to June 27 with the Goldstone Solar System Radar (which discovered the system's binary nature, operating at 3.5 cm / 8.56 GHz) and Arecibo Observatory planetary radar system (operating at 12.6 cm / 2.38 GHz). The size of the QE_2 primary and the short light travel time afforded us an excellent data set of high resolution delay-Doppler images as fine as 7.5 meters/pixel of this asteroid and its moon. We used the extensive radar dataset to fit 3D shape models for both primary and secondary using a nonlinear iterative inverse process [1,2]. A preliminary scale model for both system components is shown in the figure. The preliminary primary model is a roughly spherical body, 3.2 ± 0.3 km in effective diameter. Some radar-bright spots in the delay-Doppler images may be indicative of boulders. Lightcurve data show a rotation period of 4.749 ± 0.002 h for the primary [3]. The best fit to a subset of radar data suggests a prograde pole at (119°, +35°) in ecliptic coordinates [4]. The secondary model indicates an effective diameter of 800 ± 80 m (for a primary:secondary diameter ratio of ≈4:1) for an elongated object with a concavity on one side of the long axis. The secondary is in a tidally locked spin state with an orbital period of 31.31 ± 0.01 h hours derived from radar, and a semimajor orbital axis of 6.2 ± 0.1 km (approximately quadruple the radius of the primary). The orbit is approximately circular (e < 0.01), which is typical of most near-Earth-asteroid binary-system orbits. We assume that the primary and secondary poles are aligned with the best-fit mutual-orbit pole. All orbital parameters were derived from radar data. From orbital fits

  9. Radar evidence for diverse shapes of the primaries among binary near-Earth asteroids

    NASA Astrophysics Data System (ADS)

    Brozovic, Marina; Benner, Lance; Ford, Thomas; Springmann, Alessondra; Taylor, Patrick; Shepard, Michael; Margot, Jean-Luc; Naidu, Shantanu; Nolan, Michael; Howell, Ellen; Busch, Michael; Giorgini, Jon; Magri, Christopher

    2014-11-01

    The Arecibo and Goldstone planetary radars have been exceptionally valuable instruments for the discovery of binary and triple asteroids in the near-Earth asteroid (NEA) population. To date, 34 out of 46 known binaries and two ternaries 71% objects total) have been discovered by radar. One of the first discovered and most well studied binary systems is (66391) 1999 KW4 (Ostro et al., 2006). This was the first system with radar evidence for a prominent equatorial bulge, sloped hemispheres, and polar flattening. 1999 KW4 Alpha became a “canonical shape model” for many theoretical studies and numerical simulations on the nature of the binary systems. As the number of binaries detected by radar grew, evidence mounted that not all primaries look like 1999 KW4 Alpha. In fact, (276049) 2002 CE26 (Shepard et al., 2006) and (285263) 1998 QE2 (Springmann et al., 2014) have very rounded shapes without an obvious presence of equatorial ridges. Furthermore, (164121) 2003 YT1 (Nolan et al., in prep.), (1862) Apollo (Ford et al., in prep.), and (363599) 2006 VV2 all have irregular, moderately elongated shapes that show the presence of a bulge at only selected longitudes. All three objects also show elongations of 1.2-1.3, which is still smaller than the mean elongation of ~1.5 in the NEA radar sample. Nevertheless, numerous other primaries have KW4-like shapes such as (185851) 2000 DP107 (Naidu et al., 2011), (311066) 2004 DC (Taylor et al, 2008), and (175706) 1996 FG3 (Benner et al., in prep.). We estimate the abundance of KW4-like objects to be at least 40% of the multiple system population, based on the 41 radar-detected cases. Our results only give the lower bound because not all the dataset have the sufficient SNRs and/or the rotational coverage. Recent Goldstone delay-Doppler images of 2013 WT44 were obtained at nearly pole-on subradar latitude and clearly show evidence of an equatorial bulge, sloped hemispheres, and polar flattening. This has provided one of the

  10. Positions of asteroids obtained during 1977

    NASA Astrophysics Data System (ADS)

    Lagerkvist, C.-I.; de Sanctis, G.; Zappala, V.

    1980-04-01

    Precise positions are given for 74 asteroids observed during 1977 at the Uppsala Southern Station and at the Kvistaberg Observatory. In particular, positions are given for main-belt asteroids, Trojans, 190 Ismene, 433 Eros, asteroids marked X or XX in the Ephemerides of Minor Planets (1977), and asteroids in Marsden's critical list (1976).

  11. Investigating the surface and subsurface properties of the Didymos binary asteroid with a landed CubeSat

    NASA Astrophysics Data System (ADS)

    Murdoch, Naomi; Cadu, Alexandre; Mimoun, David; Karatekin, Ozgur; Garcia, Raphael; Carrasco, José; Garcia de Quiros, Javier; Vasseur, Hugues; Ritter, Birgit; Eubanks, Marshall; Radley, Charles; Dehant, Veronique

    2016-04-01

    Despite the successes of recent space missions (e.g., Cheng et al., 1997; Fujiwara et al., 2006), there is still no clear understanding of the asteroid internal structure(s). Depending on their size, evolution and physical properties, many different asteroid internal structure models have been suggested from completely cohesive bodies, through to rubble pile objects. The Asteroid Geophysical Explorer (AGEX), a COPINS payload selected by ESA*, will land geophysical instrument packages on the surface of Didymoon; the secondary object in the (65803) Didymos (1996 GT) binary system (Karatekin et al 2016). The instruments will characterize the asteroid surface mechanical properties and probe, for the first time, the sub-surface structure of an asteroid. AGEX will be deployed from AIM on a ballistic transfer to the asteroid surface, several days before the MASCOT-2 package. We expect that AGEX will bounce multiple times before coming to rest on the surface of the asteroid thus providing a unique opportunity to study the asteroid surface properties, perhaps at several locations, using accelerometers. Once stationary, the seismological surface-monitoring phase, using a three-axis set of geophones, can begin. The high speed DART impact will be a major seismic source on Didymoon. However, the seismic payload may also be able to perform seismological investigations using natural seismic sources such as micrometeoroid impacts (e.g., Garcia et al., 2015), thermal cracks (e.g., Delbo et al., 2014), internal quakes due to tidal forces (e.g., Richardson et al. 1998) and other geophysical processes (see Murdoch et al., 2015). We will present the expected signal characteristics of the landing and also of the natural seismic sources that may occur on Didymoon. An understanding of the amplitude and frequency content of such signals is necessary in order to design the optimal geophysical payload for small body exploration using a CubeSat platform. [1.] Cheng, A. et al., Journal of

  12. Orbital Motion in the Vicinity of the Non-collinear Equilibrium Points of a Contact Binary Asteroid

    NASA Astrophysics Data System (ADS)

    Feng, Jinglang; Noomen, Ron; Yuan, Jianping

    2015-11-01

    The orbital motion around the non-collinear equilibrium points (EPs) of a contact binary asteroid is investigated in this paper. A contact binary asteroid is an asteroid consisting of two lobes that are in physical contact. Here, it is represented by the combination of an ellipsoid and a sphere. The gravity field of the ellipsoid is approximated by a spherical harmonic expansion with terms C20 ,C22 and C40, and the sphere by a straightforward point mass model. The non-collinear EPs are linearly stable for asteroids with slow rotation rates, and become unstable as the rotation rate goes up. To study the motion around the stable EPs, a third-order analytical solution is constructed, by the Lindstedt-Poincaré (LP) method. A good agreement is found between this analytical solution and numerical integrations for the motion in the vicinity of the stable EPs. Its accuracy decreases when the orbit goes further away from the EPs and the asteroid rotates faster. For the unstable EPs, the motions around them are unstable as well. Therefore, the linear feedback control law based on low thrust is introduced to stabilize the motion and track the reference trajectory. In addition, more control force is required as any of the injection error, the amplitude of the analytical reference orbit or the rotation rate of the asteroid increases. For small orbits around the EPs, the third-order analytical solution can serve as a good reference trajectory. However, for large amplitude orbits, accurate numerical orbits are to be used as reference. This avoids an extra control force to track the less accurate third-order analytical solution.

  13. On the stability of Earth's Trojans

    NASA Astrophysics Data System (ADS)

    Lhotka, Ch.; Zhou, L. Y.; Dvorak, R.

    2012-12-01

    The gas giants Jupiter and Neptune are known to host Trojans, and also Mars has co-orbiting asteroids. Recently, in an extensive numerical investigation the possibility of captures of asteroids by the terrestrial planets and even the Earth into the 1:1 mean motion resonance (MMR) was studied. The first Earth Trojan has been observed and found to be in a so-called tadpole orbit closed to the Lagrange point L4. We did a detailed study of the actual orbit of this Trojan 2010 TK7 including the study of clone orbits, derived an analytical mapping in a simplified dynamical system (Sun+Earth+massless asteroid) and studied the phase space structure of the Earth's Lagrange points with respect to the eccentricities and the inclinations of a large number of fictitious Trojans. The extension of stable zones around the Lagrange points is established with the aid of dynamical mappings; the known Trojan 2010 TK7 finds himself inside an unstable zone.

  14. Radar imaging of binary near-Earth asteroid (357439) 2004 BL86

    NASA Astrophysics Data System (ADS)

    Benner, Lance A. M.; Brozovic, Marina; Giorgini, Jon D.; Taylor, Patrick A.; Howell, Ellen S.; Busch, Michael W.; Nolan, Michael C.; Jao, Joseph S.; Lee, Clement G.; Ford, H. Alyson; Ghigo, Frank D.

    2015-11-01

    We report radar imaging of near-Earth asteroid 2004 BL86 obtained at Goldstone, Arecibo, Green Bank, and elements of the Very Long Baseline Array between 2015 January 26-31. 2004 BL86 approached within 0.0080 au on January 26, the closest known approach by any object with an absolute magnitude brighter than ~19 until 2027. Prior to the encounter, virtually nothing was known about its physical properties other than its absolute magnitude of 19, which suggested a diameter within a factor of two of 500 m. 2004 BL86 was a very strong radar target that provided an outstanding opportunity for radar imaging and physical characterization. Delay-Doppler images with range resolutions as fine as 3.75 m placed thousands of pixels on the object and confirmed photometric results reported by Pravec et al. (2015, CBET 4063) that 2004 BL86 is a binary system. During the observations, the asteroid moved more than 90 deg and provided a range of viewing geometries. The bandwidth was relatively narrow on Jan. 26, reached a maximum on Jan. 27, and then narrowed on Jan. 28, a progression indicating that the subradar latitude moved across the equator during those days. The images reveal a rounded primary with an equatorial diameter of ~350 m, evidence for ridges, possible boulders, and a pronounced angular feature ~100 m in diameter near one of the poles. Images from Jan. 26 show arcs of radar-bright pixels on the approaching and receding limbs that extend well behind the trailing edge in the middle of the echo. This is the delay-Doppler signature of an oblate shape seen at least a few tens of degrees off the equator. A rough estimate for the diameter of the secondary is ~70 m and its narrow bandwidth is consistent with the 14-h orbital period reported by Pravec et al. (2015). The images are suitable for 3D shape, pole, orbit, and mass estimation. The observations utilized new data taking equipment at Green Bank to receive X-band (8560 MHz, 3.5 cm) transmissions from the 70 m DSS-14

  15. Spitzer Space Telescope Albedo Survey of Small Jovian Trojans

    NASA Astrophysics Data System (ADS)

    Fernandez, Yanga R.; Jewitt, D. C.; Grisetti, R.; Igyarto, C.

    2006-09-01

    We will present preliminary results from our Spitzer Space Telescope (SST) survey of small Jovian Trojan asteroids. For the first time, we have been able to make thermophysical measurements of objects at the faint end of the known Trojan magnitude distribution. Our scientific goal is to determine the mean albedo of these small Trojans. Our sample contains 35 objects with approximate absolute magnitudes (H) between 13 and 14 (diameter 10 to 15 km for 0.05 albedo). For this survey we obtained 24-micron (mid-IR) photometry with the MIPS instrument aboard SST, and visible-wavelength CCD photometry using the University of Hawaii 88-inch Telescope. This lets us constrain each Trojan's effective radius and geometric albedo. While the two datasets were not simultaneous, this is not detrimental to the achievement of our goal since we only need for the effect of the rotational context to average out. In an earlier survey, we found that the mean V-band geometric albedo for large Trojans (sample median diameter of 110 km) is 0.041±0.002 (Fernandez et al. 2003, AJ 126, 1563). If the small Trojans' mean albedo is significantly higher, this would be evidence for a significant volatile component in the Trojan population having survived since formation, and would have implications for the contribution of Trojan asteroids to the Jupiter-family comet population. This research was made possible through a SIRTF Fellowship to YRF and through a GO data analysis grant from SSC to YRF and DCJ.

  16. Colors and Properties of Jupiter's Greeks and Trojans

    NASA Astrophysics Data System (ADS)

    Chatelain, Joseph; Henry, Todd J.; French, Linda M.; Trilling, David E.

    2016-10-01

    In this Ph.D. talk, I will present the colors and properties of Jupiter Trojan asteroids examined in my dissertation research. The Jupiter Trojan asteroids are minor bodies that orbit 60 degrees in front and 60 degrees behind Jupiter. Because these orbits are stable over the lifetime of the Solar System, the properties of these objects may inform us about the conditions under which the Solar System formed. We present BVRKCIKC photometry for over 100 of the intrinsically brightest and presumably largest members of the L4 and L5 Jupiter Trojans. We use a new principal color component derived by Chatelain et al. 2016 that is indicative of taxonomic types relevant to the Jupiter Trojan asteroids. We previously found that 76% of the largest L5 Jupiter Trojans are consistent with a D-type classification, while 24% show shallower slopes more consistent with X-type and C-type classifications. Here we extend this study to the L4 cloud and compare the two populations, as well as include findings about specific objects that have resulted from these data. Specifically, multiple photometric observations hint at color variation in some objects, and our richest datasets allow for the determination of phase curves and shapes for a handful of the most compelling asteroids including a new shape model and pole solution for 1173 Anchises. Our goal is to use this study to shed light on these fascinating objects and to place the Trojans in context in the larger Solar System.

  17. Rotational Properties of Jupiter Trojan 1173 Anchises

    NASA Astrophysics Data System (ADS)

    Chatelain, Joseph; Henry, Todd; French, Linda; Trilling, David

    2015-11-01

    Anchises (1173) is a large Trojan asteroid librating about Jupiter’s L5 Lagrange point. Here we examine its rotational and lightcurve properties by way of data collected over a 3.5 year observing campaign. The length of the campaign means that data were gathered for more than a quarter of Anchises' full orbital revolution which allows for accurate determinations of pole orientation and bulk shape properties for the asteroid that can then be compared to results of previous work (i.e. French 1987, Horner et al. 2012). In addition to light curves, photometric data taken during this campaign could potentially detect color differences between hemispheres as the viewing geometry changes over time. Understanding these details about a prominent member of the Jupiter Trojans may help us better understand the history of this fascinating and important group of asteroids.

  18. Concept of Operations for Deploying a Lander on the Secondary Body of Binary Asteroid 1996 FG3

    NASA Astrophysics Data System (ADS)

    Tardivel, Simon; Michel, P.; Scheeres, D.

    2012-10-01

    The European Space Agency is currently performing an assessment study of the MarcoPolo-R space mission, in the framework of the M3 class competition of its Cosmic Vision Program. MarcoPolo-R is a sample return mission to a primitive asteroid, whose baseline target is the binary asteroid 1996FG3. The baseline mission, including the sample, is focused on the primary of the binary system. To date, little has yet been considered for the investigation of the secondary, apart from remote observations from the spacecraft. However, MarcoPolo-R may carry an optional lander, and if such a lander could be accommodated it may be relevant to use it for a more detailed investigation of the secondary. This poster presents a strategy for deploying a lander using an unpowered trajectory towards the secondary. This ballistic deployment allows for the design of a light lander with minimum platform overhead and maximum payload. The deployment operations are shown to be very simple and require minimum preparation. The main spacecraft is set on an orbit that reaches a specific point near the binary system L2 Lagrange Point facing the far side of the secondary, about 220 meters from the secondary surface, with a relative speed of about 10cm/s. The lander is then jettisoned using a spring-release mechanism that sets it on an impact trajectory that robustly intersects with the secondary surface. On impact, the lander only needs to dissipate a small amount of kinetic energy in order to ensure that it is energetically and dynamically trapped on the surface. Considering errors on spacecraft GNC and on the spring-release mechanism, and very large uncertainties on the gravity field of the asteroids, the strategy presented here yields a successful landing in more than 99.9% of cases, while ensuring the absolute safety of the spacecraft before, during and after deployment operations.

  19. New Martian Trojans and an update on the Eureka cluster

    NASA Astrophysics Data System (ADS)

    Christou, A. A.; Vaduvescu, O.; Tudor, V.; Asher, D. J.; Toma, R.; Knapen, J.; Ponomareva, A. A.

    2014-04-01

    The number of known Trojan asteroids of Mars has recently increased twofold [1, 2]. This has led to claims of a cluster [2] associated with the first Mars Trojan discovered, 5261 Eureka. The existence of an asteroid family so close to the Sun has implications for our understanding of asteroid evolution in general. Depending on the formation mechanism, studying these objects will provide insight on their collisional history and their long-term physical & dynamical evolution under the Yarkovsky and YORP effects [3]. Martian Trojans are also a useful control population for the study of the resetting of asteroid surfaces by planetary close encounters [4]. The clustering claim is based on an overall sample of 6 Trojans. To confirm it, we are presently carrying out an observational programme to (a) recover singleopposition Martian Trojan candidates and increase the sample size, and (b) improve the orbits of known Trojans. At the time of abstract submission, we have con-firmed several additional asteroids as Martian Trojans, including a single-opposition object - 2011 SL25 - recovered early in 2014 using the 2.5m Isaac Newton Telescope (Isaac Newton Group, La Palma, Canary Islands; Fig. 1). We have also recovered 2011 UN63 using the 2m Faulkes Telescope South (Siding Spring, Australia), a confirmed cluster member that was nevertheless previously observed on only two apparitions. During the conference, we will present results for the additional objects, in particular whether they are cluster members or not. Using the improved statistics and orbits, we re-assess the different scenarios for the cluster's origin.

  20. New Martian Trojans and an update on the Eureka cluster

    NASA Astrophysics Data System (ADS)

    Christou, A.; Vaduvescu, O.; Tudor, V.; Asher, D.; Toma, R.; Knapen, J.

    2014-07-01

    The number of known Trojan asteroids of Mars has recently increased twofold [1,2]. This has led to claims of a cluster [2] associated with the first Mars Trojan discovered, 5261 Eureka. The existence of an asteroid family so close to the Sun has implications for our understanding of asteroid evolution in general. Depending on the formation mechanism, studying these NEO-sized objects will provide insight on their collisional history and their long-term physical/dynamical evolution under the Yarkovsky and YORP effects [3]. Martian Trojans may also be an important control population for the study of the resetting of asteroid surfaces by planetary close encounters [4]. The clustering claim is based on an overall sample of 6 Trojans. To confirm it, we are presently carrying out an observational programme to (a) recover single-opposition Martian Trojan candidates and increase the sample size, and (b) improve the orbits of known Trojans. At the time of abstract submission, we have confirmed two additional asteroids as Martian Trojans. One was observed previously on multiple apparitions but not considered in [2]; the other is a recovery of a single-opposition object using the 2.5 m lsaac Newton Telescope (Isaac Newton Group, La Palma, Canary Islands). In addition, we have recovered 2011 UN63 using the 2 m Faulkes Telescope South in Siding Spring, Australia. This is a confirmed cluster member that had nevertheless been observed previously on only two apparitions. During the conference, we will present results for the two additional objects, in particular whether they are cluster members or not. Using the improved statistics and orbits, we will re-assess the significance of the clustering and discuss its origin.

  1. A new non-convex model of the binary asteroid 90 Antiope obtained with the SAGE modelling technique

    NASA Astrophysics Data System (ADS)

    Bartczak, P.; Michałowski, T.; Santana-Ros, T.; Dudziński, G.

    2014-09-01

    We present a new non-convex model of the 90 Antiope binary asteroid, derived with a modified version of the Shaping Asteroids with Genetic Evolution (SAGE) method using disc-integrated photometry only. A new variant of the SAGE algorithm capable of deriving models of binary systems is described. The model of 90 Antiope confirms the system's pole solution (λ = 199°, β = 38°, σ = ±5°) and the orbital period (16.505 046 ± 0.000 005 h). A comparison between the stellar occultation chords obtained during the 2011 occultation and the projected shape solution has been used to scale the model. The resulting scaled model allowed us to obtain the equivalent radii (R1 = 40.4 ± 0.9 km and R2 = 40.2 ± 0.9 km) and the distance between the two system components (176 ± 4 km), leading to a total system mass of (9.14 ± 0.62) · 1017 kg. The non-convex shape description of the components permitted a refined calculation of the components' volumes, leading to a density estimation of 1.67 ± 0.23 g cm-3. The intermediate-scale features of the model may also offer new clues on the components' origin and evolution.

  2. Dynamics of ejecta from a binary asteroid impact in the framework of the AIDA mission: a NEOShield-2 contribution

    NASA Astrophysics Data System (ADS)

    Yu, Y.; Schwartz, S. R.; Michel, P.; Benner, L. A. M.

    2015-10-01

    The dynamics of the ejecta cloud that results from a binary asteroid impact is one of the tasks of the NEOShield-2 project, funded by the European Commission in its program Horizon 2020. Results from such an investigation will have great relevance to the Phase-A study of the AIDA space mission, a collaborative effort between ESA and NASA, which aims to perform a kinetic impactor demonstration. Our study presents a multi-scale dynamical model of the ejecta cloud produced by a hypervelocity impact, which enables us to check the behaviors of the ejecta at different spatial and time scales. This model is applied to the impact into the small moon of the binary Near- Earth asteroid (65803) Didymos on October 2022 as considered by the AIDA mission. We attempt to model the process by including as much practical information as possible, e.g., the gravitational environment influenced by the non-spherical shapes of the bodies based on observed shape of the primary), the solar tides, and the solar radiation pressure. Our simulations show the general patterns of motion of the ejecta cloud, which we use to assess the potential hazard to an observing spacecraft. We also look into the grain-scale dynamics of the ejecta during this process, which has influence on the re-accumulation of particles orbiting in the vicinity.

  3. Lunar and Planetary Science XXXV: Asteroids, Meteors, Comets

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Reports included:Long Term Stability of Mars Trojans; Horseshoe Asteroids and Quasi-satellites in Earth-like Orbits; Effect of Roughness on Visible Reflectance Spectra of Planetary Surface; SUBARU Spectroscopy of Asteroid (832) Karin; Determining Time Scale of Space Weathering; Change of Asteroid Reflectance Spectra by Space Weathering: Pulse Laser Irradiation on Meteorite Samples; Reflectance Spectra of CM2 Chondrite Mighei Irradiated with Pulsed Laser and Implications for Low-Albedo Asteroids and Martian Moons; Meteorite Porosities and Densities: A Review of Trends in the Data; Small Craters in the Inner Solar System: Primaries or Secondaries or Both?; Generation of an Ordinary-Chondrite Regolith by Repetitive Impact; Asteroid Modal Mineralogy Using Hapke Mixing Models: Validation with HED Meteorites; Particle Size Effect in X-Ray Fluorescence at a Large Phase Angle: Importance on Elemental Analysis of Asteroid Eros (433); An Investigation into Solar Wind Depletion of Sulfur in Troilite; Photometric Behaviour Dependent on Solar Phase Angle and Physical Characteristics of Binary Near-Earth-Asteroid (65803) 1996 GT; Spectroscopic Observations of Asteroid 4 Vesta from 1.9 to 3.5 micron: Evidence of Hydrated and/or Hydroxylated Minerals; Multi-Wavelength Observations of Asteroid 2100 Ra-Shalom: Visible, Infrared, and Thermal Spectroscopy Results; New Peculiarities of Cometary Outburst Activity; Preliminary Shape Modeling for the Asteroid (25143) Itokawa, AMICA of Hayabusa Mission; Scientific Capability of MINERVA Rover in Hayabusa Asteroid Mission; Characteristics and Current Status of Near Infrared Spectrometer for Hayabusa Mission; Sampling Strategy and Curation Plan of Hayabusa Asteroid Sample Return Mission; Visible/Near-Infrared Spectral Properties of MUSES C Target Asteroid 25143 Itokawa; Calibration of the NEAR XRS Solar Monitor; Modeling Mosaic Degradation of X-Ray Measurements of 433 Eros by NEAR-Shoemaker; Scattered Light Remediation and Recalibration of

  4. THE ROLE OF KOZAI CYCLES IN NEAR-EARTH BINARY ASTEROIDS

    SciTech Connect

    Fang, Julia; Margot, Jean-Luc

    2012-03-15

    We investigate the Kozai mechanism in the context of near-Earth binaries and the Sun. The Kozai effect can lead to changes in eccentricity and inclination of the binary orbit, but it can be weakened or completely suppressed by other sources of pericenter precession, such as the oblateness of the primary body. Through numerical integrations including primary oblateness and three bodies (the two binary components and the Sun), we show that Kozai cycles cannot occur for the closely separated near-Earth binaries in our sample. We demonstrate that this is due to pericenter precession around the oblate primary, even for very small oblateness values. Since the majority of observed near-Earth binaries are not well separated, we predict that Kozai cycles do not play an important role in the orbital evolution of most near-Earth binaries. For a hypothetical wide binary modeled after 1998 ST27, the separation is large at 16 primary radii and so the orbital effects of primary oblateness are lessened. For this wide binary, we illustrate the possible excursions in eccentricity and inclination due to Kozai cycles as well as depict stable orientations for the binary's orbital plane. Unstable orientations lead to collisions between binary components, and we suggest that the Kozai effect acting in wide binaries may be a route to the formation of near-Earth contact binaries.

  5. Planetary migration effects on the formation of Neptune Trojans

    NASA Astrophysics Data System (ADS)

    Ma, Yuehua; Chen, Yuanyuan

    2016-07-01

    Trojan asteroids formation mechanisms are closely related to giant planet formation/migration. Using test particle simulations, we investigate the orbital element distributions of Neptune Trojans affected by the processes of planetary migration and the orbital damping of Uranus and Neptune. We examine the stability of primordial Neptune Trojans, objects that were initially Trojans with Neptune prior to migration, and also study Trans-Neptunian objects captured into resonance with Neptune and becoming Neptune Trojans during planet migration. We find that most primordial Neptune Trojans were unstable and lost if eccentricity and inclination damping took place during planetary migration. With damping, secular resonances with Neptune can increase a low eccentricity and inclination population of Trans-Neptunian objects increasing the probability that they are captured into 1:1 resonance with Neptune, becoming high inclination Neptune Trojans. We suggest that the resonant trapping scenario is a promising and more effective mechanism to explain the origin of Neptune Trojans if Uranus and Neptune had orbital damping during planetary migration.

  6. The Trojan. [supersonic transport

    NASA Technical Reports Server (NTRS)

    1992-01-01

    The Trojan is the culmination of thousands of engineering person-hours by the Cones of Silence Design Team. The goal was to design an economically and technologically viable supersonic transport. The Trojan is the embodiment of the latest engineering tools and technology necessary for such an advanced aircraft. The efficient design of the Trojan allows for supersonic cruise of Mach 2.0 for 5,200 nautical miles, carrying 250 passengers. The per aircraft price is placed at $200 million, making the Trojan a very realistic solution for tomorrows transportation needs. The following is a detailed study of the driving factors that determined the Trojan's super design.

  7. Photometric colors of the brightest members of the Jupiter L5 Trojan cloud

    NASA Astrophysics Data System (ADS)

    Chatelain, Joseph P.; Henry, Todd J.; French, Linda M.; Winters, Jennifer G.; Trilling, David E.

    2016-06-01

    The L5 Jupiter Trojan asteroids are minor bodies that orbit 60 degrees behind Jupiter. Because these orbits are stable over the lifetime of the Solar System, the properties of these objects may inform us about the conditions under which the Solar System formed. We present BVRKCIKC photometry for the 42 intrinsically brightest and presumably largest members of the L5 Jupiter Trojans. We define a new principal color component aT* that is indicative of taxonomic types relevant to the Jupiter Trojan asteroids. We find that 76% of the largest L5 Jupiter Trojans are consistent with a D-type classification, while 24% show shallower slopes more consistent with X-type and C-Type classifications. Such a breakdown is consistent with other surveys and will help to place the Trojans in the larger context of the Solar System.

  8. Probing surface properties of Jupiter Trojans by polarimetric observations

    NASA Astrophysics Data System (ADS)

    Belskaya, I.; Bagnulo, S.; Stinson, A.; Christou, A.; Muinonen, K.

    2014-07-01

    We present the first polarimetric observations of six Jupiter Trojans, namely (588) Achilles, (1583) Antilochus, (3548) Eurybates, (4543) Phoinix, (6545) 1986 TR_6, and (21601) 1998 XO_{89}. All these objects belong to the L4 population of Jupiter Trojans and have diameters in the range of 50-160 km (Grav et al. 2011). The observations were carried out in 2013 at ESO VLT. Each object was observed at 3-4 different phase angles in the phase-angle range from 7 deg up to 11-12 deg, the largest possible phase angles in the ground-based observations of Trojans. Observations were made in the R band with a typical accuracy of 0.05 %. We have measured negative polarization branch for each object with polarization minima varying from -1 % to -1.3 %. The polarization-phase-angle behavior of the observed Trojans is found to be very similar to that of some low-albedo main-belt asteroids, in particular, the P-type asteroids. We compare photometric and polarimetric phase dependencies of Trojans to the phase curves of inner and outer Solar System bodies. Possible relationships of phase-curve parameters with albedos and spectral properties are investigated. Constraints on the surface properties of Jupiter Trojans from the polarimetric observations are discussed.

  9. The disposition of impact ejecta resulting from the AIDA-DART mission to binary asteroid 65803 Didymos: an independent investigation

    NASA Astrophysics Data System (ADS)

    Richardson, James E.; O'Brien, David P.

    2016-10-01

    If all goes as planned, in the year 2020 a joint ESA and NASA mission will be launched that will rendezvous with the near-Earth binary asteroid system 65803 Didymos in the fall of 2022. The European component, the Asteroid Impact & Deflection Assessment (AIDA) spacecraft will arrive first and characterize the system, which consists of a ~800 m diameter primary and a ~160 m diameter secondary, orbiting a common center of mass at a semi-major axis distance of ~1200 m with a orbital period of 11.9 hr. Following system characterization, the AIDA spacecraft will remove to a safe distance while the NASA component, the 300 kg Double Asteroid Redirection Test (DART) spacecraft collides with the trailing edge of the secondary body (with respect to the binary's retrograde mutual orbit). Meanwhile, the AIDA spacecraft will conduct observations of this impact and its aftermath, specifically looking for changes made to the primary, the secondary, and their mutual orbit as a result of the DART collision. Of particular interest is the ballistic flight and final disposition of the ejecta produced by the impact cratering process, not just from the standpoint of scientific study, but also from the standpoint of AIDA spacecraft safety.In this study, we investigate a series of hypothetical DART impacts utilizing a semi-empirical, numerical impact ejecta plume model originally developed for the Deep Impact mission and designed specifically with impacts on small bodies in mind. The resulting excavated mass is discretized into 7200 individual tracer particles, each representing a unique combination of speed, mass, and ejected direction. The trajectory of each tracer is computed numerically under the gravitational influence of both primary and secondary, along with the effects of solar radiation pressure. Each tracer is followed until it either impacts a body or escapes the system, whereupon tracking is continued in the heliocentric frame using an N-body integrator. Various impact

  10. Arecibo and Goldstone Radar Observations of the First-Recognized Binary Near-Earth Asteroid: (385186) 1994 AW1

    NASA Astrophysics Data System (ADS)

    Richardson, James E.; Taylor, Patrick A.; Rivera-Valentin, Edgard G.; Rodriguez-Ford, Linda A.; Benner, Lance A. M.; Naidu, Shantanu P.; Giorgini, Jon D.; Busch, Michael W.; Ghigo, Frank d.; Kobelski, Adam; Warner, Brian D.; Springmann, Alessondra; Marshall, Sean E.; Steckloff, Jordan K.; Sharkey, Benjamin

    2015-11-01

    Near-Earth asteroid (385186) 1994 AW1 was discovered at Palomar Observatory on 11 January 1994. Subsequent observations of this Amor family, Sa-class asteroid also identified it as the first candidate binary NEA, as indicated by multiple periodicities and possible mutual eclipsing/occulting events in the object’s lightcurve. On 15 July 2015 this asteroid made its closest approach to Earth since its discovery, coming within 0.065 AU (25 lunar distances), and prompting an extended observation campaign using both the JPL-Goldstone and Arecibo Observatory planetary radars. Goldstone observations covered the 14-19 July period of closest approach (0.066-0.070 AU) while the object remained below Arecibo’s observing horizon, with Arecibo picking up the observations between 20-30 July, as the object moved from 0.075 to 0.126 AU distance. At Goldstone, we were able to observe this object with range resolutions of 150 m using a Goldstone (DSS-14) to Green Bank Telescope (GBT) bistatic configuration, while at Arecibo, we conducted monostatic observations of 1994 AW1 using the 2380 MHz (12.6 cm) radar at resolutions of 30 m and 75 m.As a result, and twenty years after its discovery, these observations have confirmed the binary nature of 1994 AW1, showing the primary body to be about 600 m in diameter, the secondary body to be about half the diameter of the primary, with the two orbiting a common center of mass at a distance of about 1.2 km apart. Delay-Doppler image comparisons of the primary over the course of six nights (at 30 m resolution) confirm a lightcurve-derived rotation period of 2.518 +/- 0.002 hr, as >90% longitude coverage was achieved, revealing a slightly elongated, irregular surface morphology. Delay-Doppler images of the secondary reveal an elongated, irregular body which appears to be tidally locked, with its long axis pointed towards the primary as it orbits with a period of about 22 hr (also consistent with the lightcurve analysis). These very early

  11. Trojans' Odyssey: Unveiling the early history of the Solar System

    NASA Astrophysics Data System (ADS)

    Lamy, Philippe; Vernazza, Pierre; Poncy, Joel; Martinot, Vincent; Hinglais, Emmanuel; Canalias, Elisabet; Bell, Jim; Cruikshank, Dale; Groussin, Olivier; Helbert, Joern; Marzari, Francesco; Morbidelli, Alessandro; Rosenblatt, Pascal; Sierks, Holger

    2012-04-01

    In our present understanding of the Solar System, small bodies (asteroids, Jupiter Trojans, comets and TNOs) are the most direct remnants of the original building blocks that formed the planets. Jupiter Trojan and Hilda asteroids are small primitive bodies located beyond the `snow line', around respectively the L4 and L5 Lagrange points of Jupiter at ˜5.2 AU (Trojans) and in the 2:3 mean-motion resonance with Jupiter near 3.9 AU (Hildas). They are at the crux of several outstanding and still conflicting issues regarding the formation and evolution of the Solar System. They hold the potential to unlock the answers to fundamental questions about planetary migration, the late heavy bombardment, the formation of the Jovian system, the origin and evolution of trans-neptunian objects, and the delivery of water and organics to the inner planets. The proposed Trojans' Odyssey mission is envisioned as a reconnaissance, multiple flyby mission aimed at visiting several objects, typically five Trojans and one Hilda. It will attempt exploring both large and small objects and sampling those with any known differences in photometric properties. The orbital strategy consists in a direct trajectory to one of the Trojan swarms. By carefully choosing the aphelion of the orbit (typically 5.3 AU), the trajectory will offer a long arc in the swarm thus maximizing the number of flybys. Initial gravity assists from Venus and Earth will help reducing the cruise time as well as the ΔV needed for injection thus offering enough capacity to navigate among Trojans. This solution further opens the unique possibility to flyby a Hilda asteroid when leaving the Trojan swarm. During the cruise phase, a Main Belt Asteroid could be targeted if requiring a modest ΔV. The specific science objectives of the mission will be best achieved with a payload that will perform high-resolution panchromatic and multispectral imaging, thermal-infrared imaging/ radiometry, near- and mid-infrared spectroscopy, and

  12. Possible routes to spin up fission for the formation of asteroid binaries and pairs

    NASA Astrophysics Data System (ADS)

    Tanga, P.; Campo Bagatin, A.; Thirouin, A.; Cellino, A.; Comito, C.; Ortiz, J. L.; Hestroffer, D.; Richardson, D. C.

    2013-09-01

    Non-gravitational effects (such as the "YORP" acceleration by thermal emission) may change their angular momentum of asteroids up to a few tens of km to the point to prevent any kind of rotational stability. Once instability is enforced mass loss may happen in more or less abrupt ways and potentially create satellites. We are studying this problem by means of numerical simulations, which extend previous results. We show that under certain conditions the production of secondary objects of different sizes by direct splitting can be a rather common event.

  13. Trailing (L5) Neptune Trojans: 2004 KV18 and 2008 LC18

    NASA Astrophysics Data System (ADS)

    Guan, Pu; Zhou, Li-Yong; Li, Jian

    2012-11-01

    The population of Neptune Trojans is believed to be bigger than that of Jupiter Trojans and that of asteroids in the main belt, although only eight members of this distant asteroid swarm have been observed up to now. Six leading Neptune Trojans around the Lagrange point L4 discovered earlier have been studied in detail, but two trailing ones found recently around the L5 point, 2004 KV18 and 2008 LC18, have not yet been investigated. We report our investigations on the dynamical behaviors of these two new Neptune Trojans. Our calculations show that the asteroid 2004 KV18 is a temporary Neptune Trojan. Most probably, it was captured into the trailing Trojan cloud no earlier than 2.03 × 105 yr ago, and it will not maintain this position later than 1.65 × 105 yr in the future. Based on the statistics from our orbital simulations, we argue that this object is more like a scattered Kuiper belt object. By contrast, the orbit of 2008 LC18 is much more stable. Among the clone orbits spreading within the orbital uncertainties, a considerable portion of clones may survive on the L5 tadpole orbits for 4 Gyr. The strong dependence of the stability on the semimajor axis and resonant angle suggests that further observations are badly required to constrain the orbit in the stable region. We also discuss the implications of the existence and dynamics of these two trailing Trojans over the history of the solar system.

  14. Binary Near-Earth Asteroid (285263) 1998 QE2: Goldstone and Arecibo Radar Imaging and Lightcurve Observations

    NASA Astrophysics Data System (ADS)

    Springmann, Alessondra; Brozović, M.; Pravec, P.; Taylor, P. A.; Howell, E. S.; Nolan, M. C.; Benner, L. M.; Busch, M. W.; Giorgini, J. D.; Magri, C.; Margot, J.; Naidu, S. P.; Shepard, M. K.; Marshall, S. E.; Law, M. C.; Galád, A.; Világi, J.; Gary, B. L.; Hicks, M. D.; Hills, K.; Pray, D. P.; Vodniza, A. Q.

    2013-10-01

    We observed near-Earth Amor asteroid 1998 QE2 with the Goldstone and Arecibo Observatory planetary radar systems, as well as with infrared and optical telescopes in the United States, Slovakia, Australia, and Colombia. Using radar, we observed the asteroid and its moon for 12 days in May and June of 2013 with a close approach of 0.039 AU to Earth on May 31, providing high signal-to-noise delay-Doppler radar images of the binary system. On June 4 we covered one full rotation of the primary (4.75 ± 0.01 hours) with 19 meter resolution delay-Doppler images. The imaging resolution varied with observing circumstances from 7.5-75 meters/pixel, with most of the observations made at 15-30 meters/pixel resolution. Radar images show a cratered primary 3 kilometers across with an elongated secondary about 600 meters in size. For the primary to have a discovery H magnitude of 16.4, it must be optically quite dark, with a geometric albedo of about 0.06 to be consistent with the diameter of the primary. Infrared spectra taken at the IRTF show QE2 as dark and reddened, perhaps primitive. The rotation period of 4.75 hours, photometrically derived, is one of the slowest known for a primary in any NEA binary system with a similar size ratio to that of QE2. The secondary appears to be in a synchronous, approximately circular orbit of approximately 32 hours with a semimajor axis of at least four primary radii. Features in the Goldstone images show evidence for an equatorial ridge, subtle in single radar frames but evident in animations. An optical lightcurve amplitude observed between 0.17 and 0.22 magnitudes confirms modest elongation of the primary as seen in radar images. Photometric observations detected seven mutual events; more data remains to be reduced and may cover more events. We will present more detailed information on the shape of the QE2 primary as well as the orbit of the secondary, and also additional surface properties from both the infrared and optical data.

  15. The Discovery of Binary Asteroid 5674 Wolff at Isaac Aznar Observatory

    NASA Astrophysics Data System (ADS)

    Aznar Macias, Amadeo; Pravec, Petr; Oey, Julian; Groom, Roger

    2016-07-01

    We report on the discovery that minor planet 5674 Wolff is a fully-synchronous binary system with an orbital period of 93.7 ± 0.2 h. The combined primary+secondary rotation amplitude is 0.52 ± 0.02 mag. A lower limit on the secondary-to-primary mean diameter ratio is D2/D1 = 0.80.

  16. Continued activity in P/2013 P5 PANSTARRS. Unexpected comet, rotational break-up, or rubbing binary asteroid?

    NASA Astrophysics Data System (ADS)

    Hainaut, O. R.; Boehnhardt, H.; Snodgrass, C.; Meech, K. J.; Deller, J.; Gillon, M.; Jehin, E.; Kuehrt, E.; Lowry, S. C.; Manfroid, J.; Micheli, M.; Mottola, S.; Opitom, C.; Vincent, J.-B.; Wainscoat, R.

    2014-03-01

    The object P/2013 P5 PANSTARRS was discovered in August 2013, displaying a cometary tail, but its orbital elements indicated that it was a typical member of the inner asteroid main belt. We monitored the object from 2013 August 30 until 2013 October 05 using the CFHT 3.6 m telescope (Mauna Kea, HI), the NTT (ESO, La Silla), the CA 1.23 m telescope (Calar Alto), the Perkins 1.8m (Lowell) and the 0.6 m TRAPPIST telescope (La Silla). We measured its nuclear radius to be r ≲ 0.25-0.29 km, and its colours g' - r' = 0.58 ± 0.05 and r' - i' = 0.23 ± 0.06, typical for an S-class asteroid, as expected for an object in the inner asteroid belt and in the vicinity of the Flora collisional family. We failed to detect any rotational light curve with an amplitude <0.05 mag and a double-peaked rotation period <20 h. The evolution of the tail during the observations was as expected from a dust tail. A detailed Finson-Probstein analysis of deep images acquired with the NTT in early September and with the CFHT in late September indicated that the object was active since at least late January 2013 until the time of the latest observations in 2013 September, with at least two peaks of activity around 2013 June 14 ± 10 d and 2013 July 22 ± 3 d. The changes of activity level and the activity peaks were extremely sharp and short, shorter than the temporal resolution of our observations (~1 d). The dust distribution was similar during these two events, with dust grains covering at least the 1-1000 μm range. The total mass ejected in grains <1 mm was estimated to be 3.0 × 106 kg and 2.6 × 107 kg around the two activity peaks. Rotational disruption cannot be ruled out as the cause of the dust ejection. We also propose that the components of a contact binary might gently rub and produce the observed emission. Volatile sublimation might also explain what appears as cometary activity over a period of 8 months. However, while main belt comets best explained by ice sublimation are found

  17. A mission concept for a Grand Tour of Multiple Asteroid Systems

    NASA Astrophysics Data System (ADS)

    Marchis, F.; Dankanich, J.; Tricarico, P.; Bellerose, J.

    2009-12-01

    In 1993, the Galileo spacecraft imaged the first companion of asteroid, Dactyl orbiting 243 Ida, a main-belt asteroid. Since then, discoveries have been accumulated thanks to the development of high angular resolution imaging on ground-based telescopes (adaptive optics), radar observations and accurate photometric light curve measurements. To date, 180 companions of small solar system bodies (SSSBs) are known in various populations, including 100 in the asteroid main belt, 33 Near Earth Asteroids, 4 Jupiter-Trojan asteroids and 44 in the Kuiper Belt. Multiple Asteroids have been shown to be complex worlds in their own with a wide range of morphologies, dynamical histories, and structural evolution. To the exception of 243 Ida, no spacecraft has visited any of them. Investigating binary asteroid systems can verify and validate current theories on their formation and on the influence of the sun in their formation (YORP effect) and evolution (space weathering). In particular, assessing the origin of the secondary satellite, if it is of common origin or capture, can provide clue of their formation. To a larger extend, the determination of their nature, scenario formation and evolution are key to understand how planet formation occurred but also to understand i) the population and compositional structure of the SSSB today ii) how the dynamics and collisions modify this structure over time iii) what the physical properties of asteroids are (density, porosity) iv) how the surface modification processes affect our ability to determine this structure (e.g. space weathering). In addition, being able to study these properties on closeby asteroids will give a relative scale accounting for the sizes, shape, rotation periods and cratering rate of these small and young bodies. In the framework of the NASA Discovery program, we propose a mission consisting of a Grand Tour of several multiple asteroid systems, including the flyby of a near earth binary asteroid and the rendezvous

  18. The binary Kuiper-belt object 1998 WW31.

    PubMed

    Veillet, Christian; Parker, Joel Wm; Griffin, Ian; Marsden, Brian; Doressoundiram, Alain; Buie, Marc; Tholen, David J; Connelley, Michael; Holman, Matthew J

    2002-04-18

    The recent discovery of a binary asteroid during a spacecraft fly-by generated keen interest, because the orbital parameters of binaries can provide measures of the masses, and mutual eclipses could allow us to determine individual sizes and bulk densities. Several binary near-Earth, main-belt and Trojan asteroids have subsequently been discovered. The Kuiper belt-the region of space extending from Neptune (at 30 astronomical units) to well over 100 AU and believed to be the source of new short-period comets-has become a fascinating new window onto the formation of our Solar System since the first member object, not counting Pluto, was discovered in 1992 (ref. 13). Here we report that the Kuiper-belt object 1998 WW31 is binary with a highly eccentric orbit (eccentricity e approximately 0.8) and a long period (about 570 days), very different from the Pluto/Charon system, which was hitherto the only previously known binary in the Kuiper belt. Assuming a density in the range of 1 to 2 g cm-3, the albedo of the binary components is between 0.05 and 0.08, close to the value of 0.04 generally assumed for Kuiper-belt objects. PMID:11961547

  19. Evolutionary Pathways for Asteroid Satellites

    NASA Astrophysics Data System (ADS)

    Jacobson, Seth Andrew

    2015-08-01

    The YORP-induced rotational fission hypothesis is a proposed mechanism for the creation of small asteroid binaries, which make up approximately 1/6-th of the near-Earth asteroid and small Main Belt asteroid populations. The YORP effect is a radiative torque that rotationally accelerates asteroids on timescales of thousands to millions of years. As asteroids rotationally accelerate, centrifugal accelerations on material within the body can match gravitational accelerations holding that material in place. When this occurs, that material goes into orbit. Once in orbit that material coalesces into a companion that undergoes continued dynamical evolution.Observations with radar, photometric and direct imaging techniques reveal a diverse array of small asteroid satellites. These systems can be sorted into a number of morphologies according to size, multiplicity of members, dynamical orbit and spin states, and member shapes. For instance, singly synchronous binaries have short separation distances between the two members, rapidly rotating oblate primary members, and tidally locked prolate secondary members. Other confirmed binary morphologies include doubly synchronous, tight asynchronous and wide asynchronous binaries. Related to these binary morphologies are unbound paired asteroid systems and bi-lobate contact binaries.A critical test for the YORP-induced rotational fission hypothesis is whether the binary asteroids produced evolve to the observed binary and related systems. In this talk I will review how this evolution is believed to occur according to gravitational dynamics, mutual body tides and the binary YORP effect.

  20. The color-magnitude distribution of small Jupiter Trojans

    NASA Astrophysics Data System (ADS)

    Wong, Ian; Brown, Michael E.; Emery, Joshua P.

    2014-11-01

    The Jupiter Trojans constitute a population of minor bodies that are situated in a 1:1 mean motion resonance with Jupiter and are concentrated in two swarms centered about the L4 and L5 Lagrangian points. Current theories of Solar System evolution describe a scenario in which the Trojans originated in a region beyond the primordial orbit of Neptune. It is hypothesized that during a subsequent period of chaotic dynamical disruptions in the outer Solar System, the primordial trans-Neptunian planetesimals were disrupted, and a fraction of them were scattered inwards and captured by Jupiter as Trojan asteroids, while the remaining objects were thrown outwards to larger heliocentric distances and eventually formed the Kuiper belt. If this is the case, a detailed study of the characteristics of Trojans may shed light on the relationships between the Trojans and other minor body populations in the outer Solar System, and more broadly, constrain models of late Solar System evolution. Several past studies of Trojans have revealed significant bimodalities with respect to various spectroscopic and photometric quantities, indicating the existence of two groupings among the Trojans - the so-called red and less-red sub-populations. In a previous work, we used primarily photometric data from the Sloan Digital Sky Survey to categorize several hundred Trojans with absolute magnitudes in the range H<12.3 into the two sub-populations. We demonstrated that the magnitude distributions of the color sub-populations are distinct to a high confidence level, suggesting that the red and less-red Trojans were formed in different locations and/or experienced different evolutionary histories. Most notably, we found that the discrepancy between the two color-magnitude distributions is concentrated at the faint end. Here, we present the results of a follow-up study, in which we analyze color measurements of a large number of small Trojans collected using the Suprime-Cam instrument on the Subaru

  1. Asteroids IV

    NASA Astrophysics Data System (ADS)

    Michel, Patrick; DeMeo, Francesca E.; Bottke, William F.

    easy and pleasant as possible for the editors, authors, and referees. They also thank Richard Binzel, the General Editor of the Space Science Series, for his strong support and advice during this process, as well as the staff at the University of Arizona Press. Finally, editor Patrick Michel would like to thank his wife Delphine, who married him on June 14, 2013, almost at the birth of the book process. He is grateful that she was willing to put up with him as he spent many of his nights and weekends working on the book. Thanks to her support, their trajectories are as bounded as a perfectly stable asteroid binary system, and this was probably the best way to experience from the start what her life would be like with a researcher! Co-editor Bottke would also like to thank his wife Veronica and his children Kristina-Marie, Laura, and Julie, who make up his own favorite asteroid family. Since Asteroids III, the size distribution of the family members has been steadily changing, and who knows how many tiny new members it will contain by Asteroids V! Co-editor DeMeo would like to thank her husband Alfredo for his support and encouragement throughout the process of creating this book. They met at the beginning of her career in research, becoming an asteroid pair and now continuing on the same orbit in life.

  2. Visible spectral slope survey of Jupiter Trojans

    NASA Astrophysics Data System (ADS)

    Erasmus, Nicolas; Rivkin, Andrew S.; Sickafoose, Amanda A.

    2016-10-01

    Jupiter's Trojans are predicted by the Nice Model [1,2] to be Trans-Neptunian Objects (TNOs) that moved from 30+ AU to 5.2 AU during the early evolution period of the Solar System. This model, predicting giant planet migration and widespread transport of material throughout the Solar System, is however still lacking important constraints. Correlations between the composition, size, and orbital geometry of Jupiter's Trojans can provide additional information to test predicted migration and evolution models.Two main colour groups have been observed, roughly equivalent to the C (plus low-albedo X) and D classes with distinguishable spectral slopes, and one interpretation is that the two groups have different compositions [3]. Independent compositions together with hints of differing orbital inclination distributions could imply separate formation locations; therefore, determining the relative fractions of C and D asteroids at different sizes would provide a key test for Solar System dynamical models. However, there is a caveat: the distinct colour groups could also arise by other means. Regolith processes or "space weathering" such as micrometeorite impacts and UV irradiation of ice are also plausible explanations for a range of spectrographic slopes from C-like to D-like [4].Here we report on our latest survey observations at Sutherland, South Africa of approximately 50 Trojan targets using the Sutherland High Speed Optical Camera (SHOC) [5] on the 74" telescope. These observations are part of a larger multi-telescope survey to determine the spectral slopes (C-like or D-like) for multiple Trojans, focusing on those of small size. These slopes can be used to determine the relative fraction of C+X and D asteroids at different sizes to determine whether what is seen is more consistent with regolith processes or different compositions.References:[1] A. Morbidelli, et al. Nature, 435, 462-465, (2005)[2] R. Gomes, et al. Nature 435, 466-469 (2005)[3] J.P. Emery, et al. The

  3. Deployment of a lander on the binary asteroid (175706) 1996 FG3, potential target of the european MarcoPolo-R sample return mission

    NASA Astrophysics Data System (ADS)

    Tardivel, Simon; Michel, Patrick; Scheeres, Daniel J.

    2013-08-01

    The idea of deploying a lander on the secondary body of the binary primitive asteroid (175706) 1996 FG3 is investigated. 1996 FG3 is the backup target of the European sample return space mission MarcoPolo-R under assessment study at the European Space Agency in the framework of the M3 Medium-Class mission competition. The launch will take place in 2022-2024, depending on its selection at the end of 2013. A lander is indicated as an optional payload, depending on mass availability on the spacecraft. Obviously, the possible complexity of a lander deployment is also an important parameter to take into account. Here we demonstrate that, considering worst case scenarios and low requirements on the spacecraft GNC and deployment mechanism, the operations are easy to implement and safe for the main spacecraft. The concept of operations is to deploy a light lander from the L2 Lagrange point of the binary system, on a ballistic trajectory that will impact the secondary asteroid. The fundamental principles of this strategy are briefly presented and a detailed model of 1996 FG3 is considered, to which the strategy is applied. We show that the deployment is successful in 99.94% of cases.

  4. Asteroid structure

    NASA Astrophysics Data System (ADS)

    Asphaug, E.

    2014-07-01

    Even before the first space missions to asteroids, in the mid-1990s, it was known that asteroids have weird structures. Photometry indicated complicated shapes, and the pioneering radar investigations by Ostro and colleagues followed by adaptive optics campaigns and flybys showed odd binary forms, and confirmed the common presence of satellites, and indications of highly varying surface roughness. Some asteroids turned out to be dominated by a single major cratering event, while others showed no evidence of a major crater, or perhaps for global crater erasure. The first space mission to orbit an asteroid, NEAR, found a mixture of heavily cratered terrains and geomorphically active 'ponds', and indicated evidence for global seismicity from impact. The next mission to orbit an asteroid, Hayabusa, found what most agree is a rubble pile, with no major craters and an absence of fines. There is to date no direct evidence of asteroid interior geology, other than measurements of bulk density, and inferences made for mass distribution asymmetry based on dynamics, and inferences based on surface lineaments. Interpolating from the surface to the interior is always risky and usually wrong, but of course the answer is important since we are someday destined to require this knowledge in order to divert a hazardous asteroid from impact with the Earth. Even considering the near-subsurface, here we remain as ignorant as we were about the Moon in the early 1960s, whether the surface will swallow us up in dust, or will provide secure landing and anchoring points. Laboratory experimentation in close to zero-G is still in its early stages. Adventures such as mining and colonization will surely have to wait until we better know these things. How do we get from here to there? I will focus on 3 areas of progress: (1) asteroid cratering seismology, where we use the surface craters to understand what is going on inside; (2) numerical modeling of collisions, which predicts the internal

  5. Studies of asteroids, comets, and Jupiter's outer satellites

    NASA Technical Reports Server (NTRS)

    Bowell, Edward

    1991-01-01

    Observational, theoretical, and computational research was performed, mainly on asteroids. Two principal areas of research, centering on astrometry and photometry, are interrelated in their aim to study the overall structure of the asteroid belt and the physical and orbital properties of individual asteroids. Two highlights are: detection of CN emission from Chiron; and realization that 1990 MB is the first known Trojan type asteroid of a planet other than Jupiter. A new method of asteroid orbital error analysis, based on Bayesian theory, was developed.

  6. Shape Shifting Satellites in Binary Near-Earth Asteroids: Do Meteoroid Impacts Play a Role in BYORP Orbital Evolution?

    NASA Technical Reports Server (NTRS)

    Rubincam, David Parry

    2012-01-01

    Less than catastrophic meteoroid impacts over 10(exp 5) years may change the shape of small rubble-pile satellites in binary NEAs, lengthening the average BYORP (binary Yarkovsky-Radzievskii-Paddack) rate of orbital evolution. An estimate of shape-shifting meteoroid fluxes give numbers close enough to causing random walks in the semimajor axis of binary systems to warrant further investigation

  7. THE SIZE DISTRIBUTION OF THE NEPTUNE TROJANS AND THE MISSING INTERMEDIATE-SIZED PLANETESIMALS

    SciTech Connect

    Sheppard, Scott S.; Trujillo, Chadwick A.

    2010-11-10

    We present an ultra-deep survey for Neptune Trojans using the Subaru 8.2 m and Magellan 6.5 m telescopes. The survey reached a 50% detection efficiency in the R band at m{sub R} = 25.7 mag and covered 49 deg{sup 2} of sky. m{sub R} = 25.7 mag corresponds to Neptune Trojans that are about 16 km in radius (assuming an albedo of 0.05). A paucity of smaller Neptune Trojans (radii < 45 km) compared with larger ones was found. The brightest Neptune Trojans appear to follow a steep power-law slope (q = 5 {+-} 1) similar to the brightest objects in the other known stable reservoirs such as the Kuiper Belt, Jupiter Trojans, and main belt asteroids. We find a roll-over for the Neptune Trojans that occurs around a radius of r = 45 {+-} 10 km (m{sub R} = 23.5 {+-} 0.3), which is also very similar to the other stable reservoirs. All the observed stable regions in the solar system show evidence for Missing Intermediate-Sized Planetesimals (MISPs). This indicates a primordial and not collisional origin, which suggests that planetesimal formation proceeded directly from small to large objects. The scarcity of intermediate- and smaller-sized Neptune Trojans may limit them as being a strong source for the short period comets.

  8. Perturbed Trojan satellites

    NASA Astrophysics Data System (ADS)

    Morais, M. H. M.; Murray, C. D.

    1999-09-01

    We present some mechanisms that can lead to instability of initially small eccentricity Trojan-type orbits associated with planetary satellites. Dermott & Murray (1981) showed that in the context of the hierarchical restricted three-body problem (M>> m), stable small eccentricity coorbital motion associated with the mass m, occurs within a region of relative width in semi-major axis a_s=0.74 epsilon (where epsilon is the dimensionless Hill's radius). However, for large eccentricities, the size of the stable coorbital region shrinks as a_s=4 (epsilon /e)(1/2) epsilon (Namouni 1999). The perturbations from other nearby bodies can cause increases in both eccentricity and semi-major axis, leading to ejection from the coorbital region via collisions with the parent body or a nearby perturber. We show that mean motion resonances among saturnian satellites can cause chaotic diffusion of both the eccentricity and the semi-major axis of their associated Trojan orbits. Moreover, we show that secular resonances inside the coorbital regions of some uranian and saturnian satellites can induce significant increases in the eccentricity of Trojan objects. A better insight into the complicated dynamics exhibited by Trojan objects when they are being subject to perturbations is fundamental to be able to assess the likelihood of finding real examples of these configurations. Dermott & Murray (1981). Icarus 48, 1-11. Namouni (1999). Icarus 137, 293-314.

  9. New Hamiltonian expansions adapted to the Trojan problem

    NASA Astrophysics Data System (ADS)

    Páez, Rocío Isabel; Locatelli, Ugo; Efthymiopoulos, Christos

    2016-07-01

    A number of studies, referring to the observed Trojan asteroids of various planets in our Solar System, or to hypothetical Trojan bodies in extrasolar planetary systems, have emphasized the importance of so-called secondary resonances in the problem of the long term stability of Trojan motions. Such resonances describe commensurabilities between the fast, synodic, and secular frequency of the Trojan body, and, possibly, additional slow frequencies produced by more than one perturbing bodies. The presence of secondary resonances sculpts the dynamical structure of the phase space. Hence, identifying their location is a relevant task for theoretical studies. In the present paper we combine the methods introduced in two recent papers (Páez and Efthymiopoulos in Celest Mech Dyn Astron 121(2):139, 2015; Páez and Locatelli in MNRAS 453(2):2177, 2015) in order to analytically predict the location of secondary resonances in the Trojan problem. In Páez and Efthymiopoulos (2015), the motion of a Trojan body was studied in the context of the planar Elliptic Restricted Three Body or the planar Restricted Multi-Planet Problem. It was shown that the Hamiltonian admits a generic decomposition H=H_b+H_{sec} . The term H_b , called the basic Hamiltonian, is a model of two degrees of freedom characterizing the short-period and synodic motions of a Trojan body. Also, it yields a constant `proper eccentricity' allowing to define a third secular frequency connected to the body's perihelion precession. H_{sec} contains all remaining secular perturbations due to the primary or to additional perturbing bodies. Here, we first investigate up to what extent the decomposition H=H_b+H_{sec} provides a meaningful model. To this end, we produce numerical examples of surfaces of section under H_b and compare with those of the full model. We also discuss how secular perturbations alter the dynamics under H_b . Secondly, we explore the normal form approach introduced in Páez and Locatelli (2015

  10. NEOWISE: The Physical and Dynamical Properties of the Cybele, Hilda and Jovian Trojan Populations

    NASA Astrophysics Data System (ADS)

    Grav, Tommy; Mainzer, Amy; Bauer, James; Masiero, Joseph; Nugent, Carolyn; Sonnett, Sarah; Cutri, Roc Michael; Kramer, Emily

    2015-08-01

    The solar-system portion of NASA’s Wide-field Infrared Survey Explorer (WISE) mission, known as NEOWISE, has collected more than 2 million observations of more than 160,000 asteroids (Wright et al. 2010; Mainzer et al. 2010, 2012, 2014). The dataset is by far the most comprehensive set of thermal observations of asteroids and comets to date and allows for an unprecedented opportunity to derive the true, de-biased size- and albedo-frequencies of the large primitive asteroids in our Solar System. The distribution of the primitive asteroids found in the Cybele, Hilda and Jovian Trojan population are key in understanding and testing the current theories of early solar system formation and evolution.NEOWISE provided observations of more than 1200 asteroids in the Cybele population, more than 1000 in the Hilda population, and more than 1700 Jovian Trojans (Grav et al. 2011, 2012a). Through thermal modeling and de-biasing of the observed population we derive the true size and albedo distributions for these populations down to 3, 6 and 10km for the Cybele, Hilda and Jovian Trojan populations, respectively. Through an innovative method of analysis of the reflective albedo in the shortest WISE band we are able to determine the taxonomic distribution of more than 100 of the largest objects in each population (Grav et al, 2012b). We will present updated and refined de-biased models for these three populations and discuss their relationship, origins and evolutions.

  11. Trojans in habitable zones.

    PubMed

    Schwarz, Richard; Pilat-Lohinger, Elke; Dvorak, Rudolf; Erdi, Balint; Sándor, Zsolt

    2005-10-01

    With the aid of numerical experiments we examined the dynamical stability of fictitious terrestrial planets in 1:1 mean motion resonance with Jovian-like planets of extrasolar planetary systems. In our stability study of the so-called "Trojan" planets in the habitable zone, we used the restricted three-body problem with different mass ratios of the primary bodies. The application of the three-body problem showed that even massive Trojan planets can be stable in the 1:1 mean motion resonance. From the 117 extrasolar planetary systems only 11 systems were found with one giant planet in the habitable zone. Out of this sample set we chose four planetary systems--HD17051, HD27442, HD28185, and HD108874--for further investigation. To study the orbital behavior of the stable zone in the different systems, we used direct numerical computations (Lie Integration Method) that allowed us to determine the escape times and the maximum eccentricity of the fictitious "Trojan planets." PMID:16225431

  12. WISE/NEOWISE OBSERVATIONS OF THE JOVIAN TROJAN POPULATION: TAXONOMY

    SciTech Connect

    Grav, T.; Mainzer, A. K.; Bauer, J. M.; Masiero, J. R.; Nugent, C. R.

    2012-11-01

    We present updated/new thermal model fits for 478 Jovian Trojan asteroids observed with the Wide-field Infrared Survey Explorer (WISE). Using the fact that the two shortest bands used by WISE, centered on 3.4 and 4.6 {mu}m, are dominated by reflected light, we derive albedos of a significant fraction of these objects in these bands. While the visible albedos of both the C-, P-, and D-type asteroids are strikingly similar, the WISE data reveal that the albedo at 3.4 {mu}m is different between C-/P- and D-types. The albedo at 3.4 {mu}m can thus be used to classify the objects, with C-/P-types having values less than 10% and D-types have values larger than 10%. Classifying all objects larger than 50 km shows that the D-type objects dominate both the leading cloud (L {sub 4}), with a fraction of 84%, and trailing cloud (L {sub 5}), with a fraction of 71%-80%. The two clouds thus have very similar taxonomic distribution for these large objects, but the leading cloud has a larger number of these large objects, L {sub 4}/L {sub 5} = 1.34. The taxonomic distribution of the Jovian Trojans is found to be different from that of the large Hildas, which is dominated by C- and P-type objects. At smaller sizes, the fraction of D-type Hildas starts increasing, showing more similarities with the Jovian Trojans. If this similarity is confirmed through deeper surveys, it could hold important clues to the formation and evolution of the two populations. The Jovian Trojans does have similar taxonomic distribution to that of the Jovian irregular satellites, but lacks the ultra red surfaces found among the Saturnian irregular satellites and Centaur population.

  13. The Advanced Jovian Asteroid Explorer (AJAX)

    NASA Astrophysics Data System (ADS)

    Murchie, S. L.; Adams, E. Y.; Mustard, J. F.; Rivkin, A.; Peplowski, P. N.

    2015-12-01

    The Advanced Jovian Asteroid eXplorer (AJAX) is the first mission to characterize the geology, morphology, geophysical properties, and chemistry of a Trojan asteroid. The Decadal Survey outlined a notional New Frontiers class Trojan asteroid rendezvous mission to conduct geological, elemental composition, mineralogical, and geophysical investigations. AJAX, our Discovery mission proposal, addresses the Decadal Survey science goals by using a focused payload and an innovative mission design. By responding to the most important questions about the Trojan asteroids, AJAX advances our understanding of all of the Solar System. Are these objects a remnant population of the local primordial material from which the outer planets and their satellites formed, or did they originate in the Kuiper Belt? Landed measurements of major and minor elements test hypotheses for the Trojan asteroid origin, revealing the outer Solar System dynamical history. How and when were prebiotic materials delivered to the terrestrial planets? AJAX's landed measurements include C and H concentrations, necessary to determine their inventories of volatiles and organic compounds, material delivered to the inner Solar System during the Late Heavy Bombardment. What chemical and geological processes shaped the small bodies that merged to form the planets in our Solar System? AJAX investigates the asteroid internal structure, geology, and regolith by using global high-resolution stereo and multispectral imaging, determining density and estimating interior porosity by measuring gravity, and measuring regolith mechanical properties by landing. AJAX's science phase starts with search for natural satellites and dust lifted by possible cometary activity and shape and pole position determination. AJAX descends to lower altitudes for global mapping, and conducts a low flyover for high-resolution surface characterization and measurement of hydrogen abundance. Finally, it deploys a small landed package, which

  14. Trojan Horse method for direct and resonant reactions

    NASA Astrophysics Data System (ADS)

    Mukhamedzhanov, A. M.

    The Trojan Horse method (THM) is a powerful indirect technique that provides information to determine astrophysical factors for binary rearrangement processes x + A to b + B at astrophysically relevant energies by measuring the cross section for the Trojan Horse (TH) reaction a + A to y + b + B in the quasifree kinematics. The theory of the THM both for direct and resonant binary subreactions is presented based on the few-body approach and Green's function formalism. The off-energy-shell effects and initial and final state interactions have been taken into account. To treat the resonance processes we developed the half-off-energy-shell R matrix approach. Examples are presented to demonstrate how THM works.

  15. Relating binary-star planetary systems to central configurations

    NASA Astrophysics Data System (ADS)

    Veras, Dimitri

    2016-11-01

    Binary-star exoplanetary systems are now known to be common, for both wide and close binaries. However, their orbital evolution is generally unsolvable. Special cases of the N-body problem which are in fact completely solvable include dynamical architectures known as central configurations. Here, I utilize recent advances in our knowledge of central configurations to assess the plausibility of linking them to coplanar exoplanetary binary systems. By simply restricting constituent masses to be within stellar or substellar ranges characteristic of planetary systems, I find that (i) this constraint reduces by over 90 per cent the phase space in which central configurations may occur, (ii) both equal-mass and unequal-mass binary stars admit central configurations, (iii) these configurations effectively represent different geometrical extensions of the Sun-Jupiter-Trojan-like architecture, (iv) deviations from these geometries are no greater than 10°, and (v) the deviation increases as the substellar masses increase. This study may help restrict future stability analyses to architectures which resemble exoplanetary systems, and might hint at where observers may discover dust, asteroids and/or planets in binary-star systems.

  16. Asteroid mining

    NASA Technical Reports Server (NTRS)

    Gertsch, Richard E.

    1992-01-01

    The earliest studies of asteroid mining proposed retrieving a main belt asteroid. Because of the very long travel times to the main asteroid belt, attention has shifted to the asteroids whose orbits bring them fairly close to the Earth. In these schemes, the asteroids would be bagged and then processed during the return trip, with the asteroid itself providing the reaction mass to propel the mission homeward. A mission to one of these near-Earth asteroids would be shorter, involve less weight, and require a somewhat lower change in velocity. Since these asteroids apparently contain a wide range of potentially useful materials, our study group considered only them. The topics covered include asteroid materials and properties, asteroid mission selection, manned versus automated missions, mining in zero gravity, and a conceptual mining method.

  17. New 40Ar/39Ar dating of the Clearwater Lake impact structures (Québec, Canada) - Not the binary asteroid impact it seems?

    NASA Astrophysics Data System (ADS)

    Schmieder, Martin; Schwarz, Winfried H.; Trieloff, Mario; Tohver, Eric; Buchner, Elmar; Hopp, Jens; Osinski, Gordon R.

    2015-01-01

    The two Clearwater Lake impact structures (Québec, Canada) are generally interpreted as a crater doublet formed by the impact of a binary asteroid. Here, arguments are presented that raise important questions about the proposed double impact scenario. New 40Ar/39Ar dating of two virtually fresh impact melt rock samples from the ⩾36 km West Clearwater Lake impact structure yielded two statistically robust Early Permian plateau ages with a weighted mean of 286.2 ± 2.2 (2.6) Ma (2σ; MSWD = 0.33; P = 0.57). In contrast, 40Ar/39Ar results for two chloritized melt rocks from the ∼26 km East Clearwater Lake impact structure produced disturbed age spectra suggestive of a distinct extraneous argon component. Although individually weakly robust, age spectra corrected for the trapped argon component and inverse isochron plots for the East Clearwater melt rocks consistently yielded apparent ages around ∼460-470 Ma. No Permian signal was found in either of these melt aliquots. Our new 40Ar/39Ar results reproduce earlier 40Ar/39Ar plateau ages (∼283 Ma and ∼465 Ma, respectively) for the two impact structures by Bottomley et al. (1990) and are in conflict with a previous, statistically non-robust Rb-Sr age of 287 [293] ± 26 Ma for East Clearwater. The combined cluster of apparent ages of ∼460-470 Ma, derived from four different samples across the impact melt sheet, is very unlikely to represent a 'false age effect' due to the incorporation of extraneous argon into the melt; instead, it strongly favors a Middle Ordovician age for the East Clearwater impact and impact-induced hydrothermal chloritization. Moreover, the Clearwater impact structures are characterized by different natural remanent magnetizations testifying to separate geologic histories, an effect unexpected in the case of a Permian double impact. Whereas the West Clearwater impact affected Ordovician carbonates incorporated into the impact breccia, drill core reports from the 1960s concluded that

  18. Observations of V-type Binary Near-Earth Asteroids 2006 VV2 and 2008 BT18

    NASA Astrophysics Data System (ADS)

    Betzler, Alberto Silva; Novaes, Alberto Brum

    2009-07-01

    The near-Earth asteroids 2006 VV2 and 2008 BT18 were observed by the authors in 2007 April and 2008 July to determine their basic physical parameters. The absolute magnitude (H) and slope parameter (G) are 2006 VV2: H = 16.6 ± 0.2, G = 0.2 ±0.2; and 2008 BT 18: H = 18.2 ± 0.2, G = 0.2 ± 0.1. The linear phase coefficients are ß = 0.03 ± 0.01 and 0.030 ± 0.005 mag/deg. The synodic period for 2008 BT18 was determined to be P = 2.726 ± 0.007 h with a lightcurve amplitude of A = 0.045 ± 0.002 mag. For 2006 VV2, we revise our previous results for color indices, finding B-V = 0.84 ± 0.06 and V-R = 0.39 ± 0.02.

  19. Comet or Asteroid?

    NASA Astrophysics Data System (ADS)

    1997-11-01

    When is a minor object in the solar system a comet? And when is it an asteroid? Until recently, there was little doubt. Any object that was found to display a tail or appeared diffuse was a comet of ice and dust grains, and any that didn't, was an asteroid of solid rock. Moreover, comets normally move in rather elongated orbits, while most asteroids follow near-circular orbits close to the main plane of the solar system in which the major planets move. However, astronomers have recently discovered some `intermediate' objects which seem to possess properties that are typical for both categories. For instance, a strange object (P/1996 N2 - Elst-Pizarro) was found last year at ESO ( ESO Press Photo 36/96 ) which showed a cometary tail, while moving in a typical asteroidal orbit. At about the same time, American scientists found another (1996 PW) that moved in a very elongated comet-type orbit but was completely devoid of a tail. Now, a group of European scientists, by means of observations carried out at the ESO La Silla observatory, have found yet another object that at first appeared to be one more comet/asteroid example. However, continued and more detailed observations aimed at revealing its true nature have shown that it is most probably a comet . Consequently, it has received the provisional cometary designation P/1997 T3 . The Uppsala-DLR Trojan Survey Some time ago, Claes-Ingvar Lagerkvist (Astronomical Observatory, Uppsala, Sweden), in collaboration with Gerhard Hahn, Stefano Mottola, Magnus Lundström and Uri Carsenty (DLR, Institute of Planetary Exploration, Berlin, Germany), started to study the distribution of asteroids near Jupiter. They were particularly interested in those that move in orbits similar to that of Jupiter and which are located `ahead' of Jupiter in the so-called `Jovian L4 Lagrangian point'. Together with those `behind' Jupiter, these asteroids have been given the names of Greek and Trojan Heroes who participated in the famous Trojan war

  20. Trojan Tour and Rendezvous (TTR): A New Frontiers Mission to Explore the Origin and Evolution of the Early Solar System

    NASA Astrophysics Data System (ADS)

    Bell, J. F., III; Olkin, C.; Castillo, J. C.

    2015-12-01

    The orbital properties, compositions, and physical properties of the diverse populations of small outer solar system bodies provide a forensic map of how our solar system formed and evolved. Perhaps the most potentially diagnostic, but least explored, of those populations are the Jupiter Trojan asteroids, which orbit at ~5 AU in the L4 and L5 Lagrange points of Jupiter. More than 6200 Jupiter Trojans are presently known, but these are predicted to be only a small fraction of the 500,000 to 1 million Trojans >1 km in size. The Trojans are hypothesized to be either former Kuiper Belt Objects (KBOs) that were scattered into the inner solar system by early giant planet migration and then trapped in the 1:1 Jupiter mean motion resonance, or bodies formed near 5 AU in a much more quiescent early solar system, and then trapped at L4 and L5. The 2011 Planetary Science Decadal Survey identified important questions about the origin and evolution of the solar system that can be addressed by studying of the Trojan asteroids, including: (a) How did the giant planets and their satellite systems accrete, and is there evidence that they migrated to new orbital positions? (b) What is the relationship between large and small KBOs? Is the small population derived by impact disruption of the large one? (c) What kinds of surface evolution, radiation chemistry, and surface-atmosphere interactions occur on distant icy primitive bodies? And (d) What are the sources of asteroid groups (Trojans and Centaurs) that remain to be explored by spacecraft? The Trojan Tour and Rendezvous (TTR) is a New Frontiers-class mission designed to answer these questions, and to test hypotheses for early giant planet migration and solar system evolution. Via close flybys of a large number of these objects,, and orbital characterization of at least one large Trojan, TTR will enable the first-time exploration of this population. Our primary mission goals are to characterize the overall surface geology

  1. Distortion Effects on Trojan Horse Applications

    NASA Astrophysics Data System (ADS)

    Pizzone, R. G.; Spitaleri, C.; Mukhamedzhanov, A. M.; Blokhintsev, L. D.; Bertulani, C. A.; Irgaziev, B. F.; La Cognata, M.; Lamia, L.; Romano, S.

    2011-05-01

    The widths of the spectator momentum distributions in several nuclei, which have been used as Trojan Horses, have been obtained as a function of the transferred momentum. Applications of Trojan Horse method will also be discussed.

  2. The Trojan Horse method for nuclear astrophysics: Recent results for direct reactions

    SciTech Connect

    Tumino, A.; Gulino, M.; Spitaleri, C.; Cherubini, S.; Romano, S.; Cognata, M. La; Pizzone, R. G.; Rapisarda, G. G.; Lamia, L.

    2014-05-09

    The Trojan Horse method is a powerful indirect technique to determine the astrophysical factor for binary rearrangement processes A+x→b+B at astrophysical energies by measuring the cross section for the Trojan Horse (TH) reaction A+a→B+b+s in quasi free kinematics. The Trojan Horse Method has been successfully applied to many reactions of astrophysical interest, both direct and resonant. In this paper, we will focus on direct sub-processes. The theory of the THM for direct binary reactions will be shortly presented based on a few-body approach that takes into account the off-energy-shell effects and initial and final state interactions. Examples of recent results will be presented to demonstrate how THM works experimentally.

  3. The Trojan Horse method for nuclear astrophysics: Recent results for direct reactions

    NASA Astrophysics Data System (ADS)

    Tumino, A.; Spitaleri, C.; Cherubini, S.; Gulino, M.; La Cognata, M.; Lamia, L.; Pizzone, R. G.; Rapisarda, G. G.; Romano, S.

    2014-05-01

    The Trojan Horse method is a powerful indirect technique to determine the astrophysical factor for binary rearrangement processes A+x→b+B at astrophysical energies by measuring the cross section for the Trojan Horse (TH) reaction A+a→B+b+s in quasi free kinematics. The Trojan Horse Method has been successfully applied to many reactions of astrophysical interest, both direct and resonant. In this paper, we will focus on direct sub-processes. The theory of the THM for direct binary reactions will be shortly presented based on a few-body approach that takes into account the off-energy-shell effects and initial and final state interactions. Examples of recent results will be presented to demonstrate how THM works experimentally.

  4. Asteroid team

    NASA Technical Reports Server (NTRS)

    Matson, D. L.

    1988-01-01

    The purpose of this task is to support asteroid research and the operation of an Asteroid Team within the Earth and Space Sciences Division at the Jet Propulsion Laboratory (JPL). The Asteroid Team carries out original research on asteroids in order to discover, better characterize and define asteroid properties. This information is needed for the planning and design of NASA asteroid flyby and rendezvous missions. The asteroid Team also provides scientific and technical advice to NASA and JPL on asteroid related programs. Work on asteroid classification continued and the discovery of two Earth-approaching M asteroids was published. In the asteroid photometry program researchers obtained N or Q photometry for more than 50 asteroids, including the two M-earth-crossers. Compositional analysis of infrared spectra (0.8 to 2.6 micrometer) of asteroids is continuing. Over the next year the work on asteroid classification and composition will continue with the analysis of the 60 reduced infrared spectra which we now have at hand. The radiometry program will continue with the reduction of the N and Q bandpass data for the 57 asteroids in order to obtain albedos and diameters. This year the emphasis will shift to IRAS follow-up observations; which includes objects not observed by IRAS and objects with poor or peculiar IRAS data. As in previous year, we plan to give top priority to any opportunities for observing near-Earth asteroids and the support (through radiometric lightcurve observations from the IRTF) of any stellar occultations by asteroids for which occultation observation expeditions are fielded. Support of preparing of IRAS data for publication and of D. Matson for his participation in the NASA Planetary Astronomy Management and Operations Working Group will continue.

  5. Trojan horse particle invariance: The impact on nuclear astrophysics

    SciTech Connect

    Pizzone, R. G.; La Cognata, M.; Spitaleri, C.; Bertulani, C. A.; Mukhamedzhanov, A. M.; Blokhintsev, L. D.; Lamia, L.; Spartá, R.; Tumino, A.

    2014-05-02

    In the current picture of nuclear astrophysics indirect methods and, in particular, the Trojan Horse Method cover a crucial role for the measurement of charged particle induced reactions cross sections of astrophysical interest, in the energy range required by the astrophysical scenarios. To better understand its cornerstones and its applications to physical cases many tests were performed to verify all its properties and the possible future perspectives. The key to the method is the quasi-free break-up and some of its properties will be investigated in the present work. In particular, the Trojan Horse nucleus invariance will be studied and previous studies will be extended to the cases of the binary d(d, p)t and {sup 6}Li(d,α){sup 4}He reactions, which were tested using different quasi-free break-up's, namely {sup 6}Li and {sup 3}He. The astrophysical S(E)-factor were then extracted with the Trojan Horse formalism applied to the two different break-up schemes and compared with direct data as well as with previous indirect investigations. The very good agreement confirms the independence of binary indirect cross section on the chosen spectator particle also for these reactions.

  6. Principal Component Analysis of Dynamically distinct D-Type Asteroids.

    NASA Astrophysics Data System (ADS)

    Nedic, Sanja; Ziffer, J.; Campins, H.; Fernandez, Y. R.; Walker, M.

    2008-09-01

    Principal Component Analysis (PCA), a common statistically based classification technique, has been used to classify asteroids into broad spectral categories. In some cases, a spectral superclass considered in isolation may undergo sub-classification (e.g. S-type subclasses). Since D-type asteroids populate at least three distinct dynamical regions in the asteroid belt -- namely Hilda, L4 Trojans and L5 Trojans, and since the recently-developed "Nice” model (Morbidelli et al. 2005. Nature 435, 462; Levison et al. 2008, ACM 2008 abstract #8156) hypothesizes that these regions may share a common origin, examining the appropriateness of a D-type sub-classification scheme is warranted. Toward this end, we performed PCA on the D-type L4, L5, and Hilda asteroids. Our PCA was based on the Sloan Digital Sky Survey broadband colors (u - g, g - r, r - i, and i - z) of 31 L4, 24 L5, and 32 Hilda asteroids with radii ranging from approximately 5 to 45 km. PCA showed 90.2% of the variance in the spectra could be condensed into the first two principal components, PC1 and PC2, with the first and second component accounting for 50.7% and 39.4% respectively. No significant clustering is observed on a PC1 vs. PC2 plot suggesting the D-type L4, L5, and Hilda asteroids do not form three independent groups, but rather are spectrally indistinguishable. We performed several statistical analyses of the means and variances of the principal components to test the validity of this conclusion. No statistically significant difference in the means among the three groups was found, nor was there any such difference in the variances, although the statistic comparing the L4 Trojans and Hildas was close to the critical value. Further measurements of colors of both large and small Trojans and Hildas will let us continue to investigate the spectral diversity of these objects.

  7. Capture of Asteroids and Transport of Asteroid Materials to Earth

    NASA Astrophysics Data System (ADS)

    Chiu, Hong-Yee; no Team

    2014-01-01

    Recently there has been much discussion on the capture of asteroids or mining the asteroids. While the technology might be years away, in this paper we will discuss an energy efficient method to transport either a small asteroid or materials gathered from asteroids to the Earth. In particular, I will concentrate on a large and nearby asteroid, 8 Flora in the Flora Family. Generally, asteroids are located between 2 to 3 AU (astronomical unit) from the Earth, and in transporting materials from asteroids to the Earth, an energy equivalent of the gravitational potential energy difference between the Earth and the asteroids to the Sun. This amount of potential energy is a sizable fraction of the orbital kinetic energy of the Earth around the Sun. This amount of energy is considerable. In this paper I propose to use the planet Mars as a medium to remove much of the gravitational energy difference. In the case of the asteroid 8 Flora, it is only necessary to decelerate the asteroid mate- rials by a small decrement, of the order of 3 km/sec. This decrement could even be achieved (pending on the availability of technology) by mechanical devices such as catapults on 8 Flora. It is also proposed to separate a pair of contact asteroid binaries by using impulse propulsion, and to propel one component of the separated asteroids to pass by Mars to be decelerated to reach the Earth orbit and captured by the Earth or the Moon. The plausibility of this ambitious project will be discussed. The author is NASA-GSFC Astrophysicist, Retired.

  8. The Asteroid Impact Mission

    NASA Astrophysics Data System (ADS)

    Carnelli, Ian; Galvez, Andres; Mellab, Karim

    2016-04-01

    The Asteroid Impact Mission (AIM) is a small and innovative mission of opportunity, currently under study at ESA, intending to demonstrate new technologies for future deep-space missions while addressing planetary defense objectives and performing for the first time detailed investigations of a binary asteroid system. It leverages on a unique opportunity provided by asteroid 65803 Didymos, set for an Earth close-encounter in October 2022, to achieve a fast mission return in only two years after launch in October/November 2020. AIM is also ESA's contribution to an international cooperation between ESA and NASA called Asteroid Impact Deflection Assessment (AIDA), consisting of two mission elements: the NASA Double Asteroid Redirection Test (DART) mission and the AIM rendezvous spacecraft. The primary goals of AIDA are to test our ability to perform a spacecraft impact on a near-Earth asteroid and to measure and characterize the deflection caused by the impact. The two mission components of AIDA, DART and AIM, are each independently valuable but when combined they provide a greatly increased scientific return. The DART hypervelocity impact on the secondary asteroid will alter the binary orbit period, which will also be measured by means of lightcurves observations from Earth-based telescopes. AIM instead will perform before and after detailed characterization shedding light on the dependence of the momentum transfer on the asteroid's bulk density, porosity, surface and internal properties. AIM will gather data describing the fragmentation and restructuring processes as well as the ejection of material, and relate them to parameters that can only be available from ground-based observations. Collisional events are of great importance in the formation and evolution of planetary systems, own Solar System and planetary rings. The AIDA scenario will provide a unique opportunity to observe a collision event directly in space, and simultaneously from ground-based optical and

  9. Visual and near-IR spectrophotometry of asteroids

    NASA Technical Reports Server (NTRS)

    Lebofsky, Larry A.

    1991-01-01

    We have been continuing our studies of the spectral properties of dark asteroids in the solar system. From these studies we expect to learn about the distribution of volatile materials, such as water in clay materials (water of hydration) and how the asteroids may relate to the comets. Our most recent work has been concentrating on simultaneous visual and near infrared photometry near Earth, main belt, and trojan asteroids. We have made observations of some unusual asteroids such as Chiron, which has recently shown cometary activity, and 944 Hidalgo, which has a comet-like orbit. We have also begun studies of the small, dark satellites of Mars and Jupiter in order to understand better how they may relate to the steroids. Could they actually be captured asteroids or comets?

  10. Trojan search at ESO.

    NASA Astrophysics Data System (ADS)

    Elst, E. W.

    1988-09-01

    Doing minor planet research is sometimes considered a proof of bad taste among astronomers. It is a fact that asteroids, these rocky pieces between the orbits of Mars and Jupiter, have lost much of their interest, now that most of the larger ones have been catalogued: their orbits are weil known, their chemical structure has been studied and their rotation properties investigated. Hence, chasing the smaller kilometer-sized members does not seem a useful occupation. Indeed, why should they be different from the larger ones?

  11. Science with the Asteroid Impact Mission

    NASA Astrophysics Data System (ADS)

    Küppers, Michael; Michel, Patrick

    2016-04-01

    The Asteroid Impact Mission (AIM) will monitor the binary asteroid Didymos before, during, and after the impact of the projectile sent by the Double Asteroid Redirection Test (DART)spacecraft. The primary goal of the mission is to demonstrate asteroid deflection with a kinetic impactor. However, important asteroid science will be achieved as a secondary objective. AIM is the first space mission to study a binary asteroid. There are several hypotheses about how binaries form, and the comparison of the global properties (density, and surface amd interior structure) may allow to distinguish between those scenarios. For example, if the binary was formed by rotational fission of the primary, an oblate shape of the primary and a low density and tensile strength of the secondary are expected. Furthermore, observation of the DART impact will provide unique data on the reaction to small asteroids, with significant implications on the collisional evolution of the solar system and planetary rings. Landing of MASCOT-2 on the secondary will provide information about the physical surface properties of a very small asteroid, providing additional information about the evolution of those objects. We will present an overview of the scientific studies foreseen with the AIM payload and their implications on the physics of small bodies in the solar system.

  12. How fast can an asteroid spin

    NASA Technical Reports Server (NTRS)

    Weidenschilling, S. J.

    1981-01-01

    Many large asteroids are probably gravitationally bound 'rubble piles', which should approximate figures of hydrostatic equilibrium. The maximum angular velocity of such bodies is limited by formation of Jacobi ellipsoids or binary fission at about half the surface orbit frequency. The observed limiting rotation period of approximately 4 hr implies asteroidal densities of about 2-3 g/cu cm.

  13. Shaping Asteroids with Genetic Evolution (SAGE)

    NASA Astrophysics Data System (ADS)

    Bartczak, P.; Marciniak, A.

    2012-05-01

    A genetic algorithm for modelling asteroid shape and spin parameters using disk-integrated photometry. The shapes can contain concavities. First tests of the resulting models against other techniques are promising for both single and binary objects.

  14. Hunting Asteroids

    NASA Astrophysics Data System (ADS)

    Carneiro, João

    2013-04-01

    From the 25th of October to the 29th of November 2012, a group of students from the School 10B Carlos Amarante, Braga, Portugal participated in the "All-Asteroid Search Campaign Portugal 2012", sponsored by NUCLIO in Portugal (Nucleus Interactive Astronomy) and promoted internationally by the IASC (International Astronomical Search Collaboration, Hardin-Simmons University). Directed to schools, these campaigns aim to discover new asteroids and help to define more precisely the trajectories of known asteroids, predicting future collisions with asteroids. Students are taught to work with the software that analyzes images of the night sky that helps to discover new asteroids and confirm the existing ones. This school project serves to promote scientific research in astronomy among students; analyze images of the night sky; identify objects in motion, which could be known asteroids, but whose orbit must be confirmed regularly. This way, we hope to inspire a growing interest for science in the students.

  15. A Trojan Horse in Birmingham

    ERIC Educational Resources Information Center

    Yarker, Patrick

    2014-01-01

    "Trojan Horse" has become journalistic shorthand for an apparent attempt by a small group in East Birmingham to secure control of local non-faith schools and impose policies and practices in keeping with the very conservative (Salafist and Wahhabi) version of Islam which they hold. In this article, Pat Yarker gives an account of two…

  16. AIDA: Asteroid Impact & Deflection Assessment

    NASA Astrophysics Data System (ADS)

    Cheng, A. F.; Galvez, A.; Carnelli, I.; Michel, P.; Rivkin, A.; Reed, C.

    2012-12-01

    To protect the Earth from a hazardous asteroid impact, various mitigation methods have been proposed, including deflection of the asteroid by a spacecraft impact. AIDA, consisting of two mission elements, the Double Asteroid Redirection Test (DART) and the Asteroid Impact Monitoring (AIM) mission, is a demonstration of asteroid deflection. To date, there has been no such demonstration, and there is major uncertainty in the result of a spacecraft impact onto an asteroid, that is, the amount of deflection produced by a given momentum input from the impact. This uncertainty is in part due to unknown physical properties of the asteroid surface, such as porosity and strength, and in part due to poorly understood impact physics such that the momentum carried off by ejecta is highly uncertain. A first mission to demonstrate asteroid deflection would not only be a major step towards gaining the capability to mitigate an asteroid hazard, but in addition it would return unique information on an asteroid's strength, other surface properties, and internal structure. This information return would be highly relevant to future human exploration of asteroids. We report initial results of the AIDA joint mission concept study undertaken by the Johns Hopkins Applied Physics Laboratory and ESA with support from NASA centers including Goddard, Johnson and Jet Propulsion Laboratory. For AIDA, the DART spacecraft impactor study is coordinated with an ESA study of the AIM mission, which would rendezvous with the same asteroid to measure effects of the impact. Unlike the previous Don Quijote mission study performed by ESA in 2005-2007, DART envisions an impactor spacecraft to intercept the secondary member of a binary near-Earth asteroid. DART includes ground-based observations to measure the deflection independently of the rendezvous spacecraft observations from AIM, which also measures deflection and provides detailed characterization of the target asteroid. The joint mission AIDA

  17. Detection of Sulfur Reddening Agents in Irradiated Jupiter Trojans Ice Analogs

    NASA Astrophysics Data System (ADS)

    Mahjoub, Ahmed; Poston, Michael; Blacksberg, Jordana; Brown, Michael E.; Hand, Kevin P.; Eiler, John; Ehlmann, Bethany; Hodyss, Robert; Carlson, Robert W.; Choukroun, Mathieu; Wong, Ian

    2016-10-01

    Dynamical models, such as the Nice model, suggest that Trojan asteroids are formed out of the same body of material that produced the Kuiper Belt. In addition, telescopic observations show a color bimodality in VNIR spectral slopes of both Trojan asteroids and small KBOs. In one hypothesis, Wong & Brown (AJ, 2016, in revision) interpret the spectrally red and less red Trojans as descendant of sulfur-containing and sulfur-less primordial trans-Neptunian objects that experienced heating and irradiation during their migration inward. A sharp difference in the surface composition (i.e. presence or absence of sulfur) of the common progenitors of KBOs and Trojans would lead to different products of radiation chemistry, which in turn could lead to the observed color bimodality. In this paper, we address the issue of color bimodality through laboratory simulation. Electron irradiation products of ices containing CH3OH-NH3-H2O (without H2S) and H2S-CH3OH-NH3-H2O (with H2S) were examined. Temperature Programmed Desorption (TPD) of the post-irradiation mixtures shows mass spectra corresponding to small red sulfur allotropes (S2, S3, S4) desorbing while heating H2S-containing films. The production of these small allotropes likely contributes to the reddening slope observed in previously reported "with H2S" samples (Poston, M., et al. LPSC #2265, 2015) and adds significant soundness to the hypothesis connecting the color bimodality in Jupiter Trojans to sulfur chemistry. These small polymers are reactive and could further polymerize due to thermal processing, producing larger yellow sulfur polymers. We hypothesize that such polymerization would occur as a consequence of heating and increased irradiation experienced by an object as it migrated from the primordial trans-Neptunian disk to the current orbit of Trojans. This could explain the difference in the degree of spectral reddening observed between KBOs and Trojans.This work has been supported by the Keck Institute for Space

  18. Asteroid Properties from Photometric Observations: Constraining Non-Gravitational Processes in Asteroids

    NASA Astrophysics Data System (ADS)

    Pravec, P.

    2013-05-01

    From October 2012 we run our NEOSource project on the Danish 1.54-m telescope on La Silla. The primary aim of the project is to study non-gravitational processes in asteroids near the Earth and in their source regions in the main asteroidal belt. In my talk, I will give a brief overview of our current knowledge of the asteroidal non- gravitational processes and how we study them with photometric observations. I will talk especially about binary and paired asteroids that appear to be formed by rotational fission, about detecting the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) and BYORP (binary YORP) effects of anisotropic thermal emission from asteroids that change their spins and satellite orbits, and about non-principal axis rotators (the so called "tumblers") among the smallest, super-critically rotating asteroids with sizes < 100 meters.

  19. Long-Term Evolution of Neptune Trojans

    NASA Astrophysics Data System (ADS)

    Tello, E.; Di Sisto, R. P.; Brunini, A.

    2015-10-01

    Neptune Trojans are objects that share the orbit with the planet Neptune and are in a neighborhood of the Lagrangian points L4 and L5 located 60({°) } "front" and 60({°) } "behind" the planet in its orbit. So far, there have been nine Neptune Trojans discovered. However stability studies indicate that this population should be large. In this work we report the results of numerical simulations of the evolution of fictitious Neptune Trojans, to detect stability and instability areas and also to study the escape of Trojans over the age of the Solar System.

  20. Shared origin for seven of Mars Trojans - impact ejecta from Mars?

    NASA Astrophysics Data System (ADS)

    Polishook, David; Jacobson, Seth A.; Aharonson, Oded

    2016-10-01

    Seven out of nine Mars Trojans belong to an orbital grouping that started to spread about 109 years ago (Cuk et al. 2015). We spectrally observed two of them (311999 and 385250) using the IRTF telescope and found that both present an identical olivine-rich reflectance spectrum, that is similar to the reflectance spectrum of (5261) Eureka, the largest of these seven Trojans (Rivkin et al. 2007). These measurements confirm the shared origin of the seven. Moreover, olivine-rich reflectance spectra is rare within asteroids, but is visible in numerous locations on Mars and is found within SNC meteorites that are argued to originate from Mars (Chassigny, ALHA77005; McSween 1985). This spectral resemblance encourages us to suggest that the seven Trojans are impact ejecta from Mars' plutonic rock. We will present dynamical calculations showing how the impact ejecta could have been caught in L5 and that there are enough size-relevant craters on Mars surface to produce these seven Trojans.

  1. Asteroid Impact & Deflection Assessment mission: Kinetic impactor

    NASA Astrophysics Data System (ADS)

    Cheng, A. F.; Michel, P.; Jutzi, M.; Rivkin, A. S.; Stickle, A.; Barnouin, O.; Ernst, C.; Atchison, J.; Pravec, P.; Richardson, D. C.

    2016-02-01

    The Asteroid Impact & Deflection Assessment (AIDA) mission will be the first space experiment to demonstrate asteroid impact hazard mitigation by using a kinetic impactor to deflect an asteroid. AIDA is an international cooperation, consisting of two mission elements: the NASA Double Asteroid Redirection Test (DART) mission and the ESA Asteroid Impact Mission (AIM) rendezvous mission. The primary goals of AIDA are (i) to test our ability to perform a spacecraft impact on a potentially hazardous near-Earth asteroid and (ii) to measure and characterize the deflection caused by the impact. The AIDA target will be the binary near-Earth asteroid (65803) Didymos, with the deflection experiment to occur in late September, 2022. The DART impact on the secondary member of the binary at ~7 km/s is expected to alter the binary orbit period by about 4 minutes, assuming a simple transfer of momentum to the target, and this period change will be measured by Earth-based observatories. The AIM spacecraft will characterize the asteroid target and monitor results of the impact in situ at Didymos. The DART mission is a full-scale kinetic impact to deflect a 150 m diameter asteroid, with known impactor conditions and with target physical properties characterized by the AIM mission. Predictions for the momentum transfer efficiency of kinetic impacts are given for several possible target types of different porosities, using Housen and Holsapple (2011) crater scaling model for impact ejecta mass and velocity distributions. Results are compared to numerical simulation results using the Smoothed Particle Hydrodynamics code of Jutzi and Michel (2014) with good agreement. The model also predicts that the ejecta from the DART impact may make Didymos into an active asteroid, forming an ejecta coma that may be observable from Earth-based telescopes. The measurements from AIDA of the momentum transfer from the DART impact, the crater size and morphology, and the evolution of an ejecta coma will

  2. 1984 AB - A unique Mars-crossing asteroid

    NASA Technical Reports Server (NTRS)

    Helin, E. F.; Dunbar, R. S.

    1984-01-01

    Asteroid 1984 AB, discovered in January 1984, proved to be a unique object with a close dynamical relationship to Mars. A brief history of the discovery and subsequent 'evolution' of the orbit as it was refined is presented. The preliminary orbit of 1984 AB indicated that it might be a Mars Trojan, and an extended discussion of this interesting possibility is presented, but this hypothesis had to be dismissed after further observations had refined the orbit. The semimajor axis and orbital eccentricity are very similar to that of Mars. No other known Mars-crossing asteroid exists with an orbit as closely associated to Mars.

  3. Investigation of asteroids in Pulkovo Observatory

    NASA Astrophysics Data System (ADS)

    Devyatkin, A.; Gorshanov, D.; L'vov, V.; Tsekmeister, S.; Petrova, S.; Martyusheva, A.; Slesarenko, V.; Naumov, K.; Sokova, I.; Sokov, E.; Zinoviev, S.; Karashevich, S.; Ivanov, A.; Lyashenko, A.; Rusov, S.; Kouprianov, V.; Bashakova, E.; Melnikov, A.

    2015-08-01

    Observational Astrometry Laboratory and Ephemeris Provision Sector of Pulkovo Observatory carry out a joint multipurpose research on asteroids belonging to various groups. Astrometric and photometric observations are done using ZA-320M and MTM-500M telescopes located at Pulkovo and in Northern Caucasus mountains, correspondingly. We obtain lightcurves that allow us to determine spin parameters and shapes of asteroids. Their color indices and taxonomy classes are derived from wideband filter observations. Improvement of asteroid orbits is achieved by doing positional measurements. Orbital evolution of asteroids is modelled, taking into account also non-gravity forces, including light pressure and Yarkovsky effect. NEAs, as well as binary asteroids, take an important place in our investigations. Quasi-satellites of Venus, Earth, and Mars are new targets of our research, one of the examples being 2012DA14 that approached Earth in early 2013; many MTM-500M observations of this asteroid were obtained around the date of approach.

  4. CHAOTIC CAPTURE OF NEPTUNE TROJANS

    SciTech Connect

    Nesvorny, David; Vokrouhlicky, David

    2009-06-15

    Neptune Trojans (NTs) are swarms of outer solar system objects that lead/trail planet Neptune during its revolutions around the Sun. Observations indicate that NTs form a thick cloud of objects with a population perhaps {approx}10 times more numerous than that of Jupiter Trojans and orbital inclinations reaching {approx}25 deg. The high inclinations of NTs are indicative of capture instead of in situ formation. Here we study a model in which NTs were captured by Neptune during planetary migration when secondary resonances associated with the mean-motion commensurabilities between Uranus and Neptune swept over Neptune's Lagrangian points. This process, known as chaotic capture, is similar to that previously proposed to explain the origin of Jupiter's Trojans. We show that chaotic capture of planetesimals from an {approx}35 Earth-mass planetesimal disk can produce a population of NTs that is at least comparable in number to that inferred from current observations. The large orbital inclinations of NTs are a natural outcome of chaotic capture. To obtain the {approx}4:1 ratio between high- and low-inclination populations suggested by observations, planetary migration into a dynamically excited planetesimal disk may be required. The required stirring could have been induced by Pluto-sized and larger objects that have formed in the disk.

  5. Asteroid taxonomy

    NASA Technical Reports Server (NTRS)

    Tholen, David J.; Barucci, M. Antonietta

    1989-01-01

    The spectral reflectivity of asteroid surfaces over the wavelength range of 0.3 to 1.1 micron can be used to classify these objects into several broad groups with similar spectral characteristics. The three most recently developed taxonomies group the asteroids into 9, 11, or 14 different clases, depending on the technique used to perform the analysis. The distribution of the taxonomic classes shows that darker and redder objects become more dominant at larger heliocentric distances, while the rare asteroid types are found more frequently among the small objects of the planet-crossing population.

  6. Studies on solar system dynamics. I - The stability of Saturnian Trojans

    NASA Astrophysics Data System (ADS)

    Innanen, K. A.; Mikkola, S.

    1989-03-01

    Numerical N-body integrations show that there may exist stable 1-1 resonance orbits of minor planets for each of the outer planets from Jupiter to Neptune. In Jupiter's case, these are the Trojan asteroids. Such orbits show no sign of instability, for at least ten million yr. For Saturn, the existence of such orbits is surprising because of the periodic proximity of Jupiter. This case was studied in some detail, and evidence was found of the importance of resonances in the stability of the Saturnian triangular Lagrangian points. The results of the numerical study are discussed, including the possibilities for constructing an analytic theory and what phenomena must be included in the treatment of the problem. The possibilities of observational confirmation of the conclusions are also considered. There is preliminary evidence for similar stability for the Trojan analogs of some of the inner planets.

  7. HST Observations of a Large-Amplitude, Long-Period Trojan: (11351) Leucus

    NASA Astrophysics Data System (ADS)

    Noll, Keith S.; Levison, Harold F.; Buie, Marc W.; Grundy, William M.

    2016-10-01

    (11351) Leucus (1997 TS25) is a Trojan that is notable for having one of the longest known rotation periods of any small body, T=514 h. A possible cause for this long period would be the existence of a tidally locked binary similar to the already-known long period binary Trojan, (617) Patroclus. If this were the case, the system would become tidally circularized in a time short compared to the age of the solar system. In such a case, the components would be separated by ~0.18 arcsec at lightcurve maximum, resolvable by WFC3. We carried out observations in June 2016, coordinated with groundbased observations to schedule near a maximum to test whether (11351) Leucus is binary. We describe the results of these observations.Observations of (11351) Leucus are of particular interest because it is a target of the Lucy mission, a Discovery mission currently in phase A and one of five that may be selected in early 2017. Searches for binary Trojans also offer multiple scientific benefits independent of mission status. Orbit-derived mass and density can be used to constrain planetary migration models. Low density is characteristic of bodies found in the dynamically cold Kuiper Belt, a remnant of the solar system's protoplanetary disk. Only one undisputed density has been measured in the Trojans, that of the binary (617) Patroclus, which has a low density of 0.8 g/cm3, similar to the low densities found in the Kuiper Belt. Slow rotators offer a set of targets that are tidally evolved systems and therefore are among the most attractive potential targets for an HST search.

  8. AIDA: Asteroid Impact & Deflection Assessment

    NASA Astrophysics Data System (ADS)

    Cheng, Andrew F.; Rivkin, A.; Galvez, A.; Carnelli, I.; Michel, P.; Reed, C.

    2012-10-01

    Near Earth objects are small bodies orbiting the Sun near Earth’s orbit, some of which impact the Earth. The impact of an object as large as 30 m in diameter occurs every few centuries. The impact of such an object would already release an energy of at least a megaton of TNT, and the impact of a larger object, which would occur less often, would be even more hazardous. To protect the Earth from a potential asteroid impact, various mitigation methods have been proposed, including deflection of the asteroid by a spacecraft impact. The Double Asteroid Redirection Test (DART) is such an asteroid mitigation mission concept. This mission would be a valuable precursor to human spaceflight to an asteroid, as it would return unique information on an asteroid’s strength and internal structure and would be particularly relevant to a human mission for asteroid mitigation. We report initial results of the AIDA joint mission concept study undertaken by the Johns Hopkins Applied Physics Laboratory and ESA with support from NASA centers including Goddard, Johnson and Jet Propulsion Laboratory. For AIDA, the DART study is coordinated with an ESA study of an Asteroid Impact Monitoring (AIM) mission, which would rendezvous with the same target. AIDA follows the previous Don Quijote mission study performed by ESA in 2005-2007, with the objective of demonstrating the ability to modify the trajectory of an asteroid and measure the trajectory change. Don Quijote involved an orbiter and an impactor spacecraft, with the orbiter arriving first and measuring the deflection, and with the orbiter making additional characterization measurements. Unlike Don Quijote, DART envisions an impactor spacecraft to intercept the secondary member of a binary near-Earth asteroid, with ground-based observations to measure the deflection as well as additional spacecraft observations from AIM. Low cost mission approaches will be presented.

  9. Asteroid resources

    NASA Technical Reports Server (NTRS)

    Lewis, John S.

    1992-01-01

    There are three types of possible asteroidal materials that appear to be attractive for exploitation: (1) volatiles, (2) free metals, and (3) bulk dirt. Because some of the near-Earth asteroids are energetically more accessible than the Moon (require a round-trip total change in velocity less than 9 km/sec, though the trip time would be measured in years not days), such an asteroid might be chosen as the source of any useful material, even if that material was also available on the Moon. Provided that the asteroid was minable, it might therefore be chosen as the source of bulk dirt needed for shielding in low Earth orbit (LEO) or elsewhere in near-Earth space. And the near-Earth asteroids may offer materials that are rare or absent on the surface of the Moon. The relationship between asteroids and meteorites is discussed. A brief overview of the entire range of meteorite compositions, with emphasis on the occurrence of interesting resources is presented. Focus is on materials useful in space, especially volatiles, metals, and raw dirt. Those few materials that may have sufficiently high market value to be worth returning to Earth will be mentioned.

  10. Finding 'paydirt' on the moon and asteroids

    NASA Technical Reports Server (NTRS)

    Staehle, R. L.

    1983-01-01

    Lunar polar region water ice, the Trojan asteroids of the earth, accessible, volatile substance-rich near-earth asteroids, and lunar gas deposits, are theoretically identified extraterrestrial resources for application to space transportation whose existence and economical exploitability could be confirmed by explorations conducted with relatively simple spacecraft. Any of these resources could improve the economics of interorbit transportation, thereby permitting launch vehicle payloads to be devoted to the transport of revenue-generating or services-providing equipment, rather than to the large propellant volumes required for the placing of large payloads on station. Among the verification missions cited is a simple lunar prospector orbiter, carrying a gamma-ray spectrometer and an electromagnetic sounder, which could ascertain the presence of water ice at the lunar poles.

  11. Visible spectroscopic and photometric survey of Jupiter Trojans: Final results on dynamical families

    NASA Astrophysics Data System (ADS)

    Fornasier, S.; Dotto, E.; Hainaut, O.; Marzari, F.; Boehnhardt, H.; De Luise, F.; Barucci, M. A.

    2007-10-01

    We present the results of a visible spectroscopic and photometric survey of Jupiter Trojans belonging to different dynamical families. The survey was carried out at the 3.5 m New Technology Telescope (NTT) of the European Southern Observatory (La Silla, Chile) in April 2003, May 2004 and January 2005. We obtained data on 47 objects, 23 belonging to the L5 swarm and 24 to the L4 one. These data together with those already published by Fornasier et al. [Fornasier, S., Dotto, E., Marzari, F., Barucci, M.A., Boehnhardt, H., Hainaut, O., de Bergh, C., 2004a. Icarus 172, 221-232] and Dotto et al. [Dotto, E., Fornasier, S., Barucci, M.A., Licandro, J., Boehnhardt, H., Hainaut, O., Marzari, F., de Bergh, C., De Luise, F., 2006. Icarus 183, 420-434], acquired since November 2002, constitute a total sample of visible spectra for 80 objects. The survey allows us to investigate six families (Aneas, Anchises, Misenus, Phereclos, Sarpedon, Panthoos) in the L5 cloud and four L4 families (Eurybates, Menelaus, 1986 WD and 1986 TS6). The sample that we measured is dominated by D-type asteroids, with the exception of the Eurybates family in the L4 swarm, where there is a dominance of C- and P-type asteroids. All the spectra that we obtained are featureless with the exception of some Eurybates members, where a drop-off of the reflectance is detected shortward of 5200 Å. Similar features are seen in main belt C-type asteroids and commonly attributed to the intervalence charge transfer transition in oxidized iron. Our sample comprises fainter and smaller Trojans as compared to the literature's data and allows us to investigate the properties of objects with estimated diameter smaller than 40-50 km. The analysis of the spectral slopes and colors versus the estimated diameters shows that the blue and red objects have indistinguishable size distribution, so any relationship between size and spectral slopes has been found. To fully investigate the Trojans population, we include in our

  12. Olivine Composition of the Mars Trojan 5261 Eureka: Spitzer IRS Data

    NASA Technical Reports Server (NTRS)

    Lim, L. F.; Burt, B. J.; Emery, J. P.; Mueller, M.; Rivkin, A. S.; Trilling, D.

    2011-01-01

    The largest Mars trojan, 5261 Eureka, is one of two prototype "Sa" asteroids in the Bus-Demeo taxonomy. Analysis of its visible/near-IR spectrum led to the conclusion that it might represent either an angritic analog or an olivine-rich composition such as an R chondrite. Spitzer IRS data (5-30 micrometers) have enabled us to resolve this ambiguity. The thermal-IR spectrum exhibits strong olivine reststrahlen features consistent with a composition of approximately equals Fo60-70. Laboratory spectra of R chondrites, brachinites, and chassignites are dominated by similar features.

  13. Asteroid researches in ASPIN/ISON project

    NASA Astrophysics Data System (ADS)

    Molotov, Igor; Schildknecht, Thomas; Inasaridze, Raguli; Elenin, Leonid; Krugly, Yurij; Rumyantsev, Vasilij; Namkhai, Tungalag; Schmalz, Sergei; Reva, Inna

    2016-07-01

    International Scientific Optical Network (ISON) represents one of largest systems specializing in observation of space objects. The main goal of project is observations of space debris. As an additional task the regular research of asteroids are carried out under ASPIN (Asteroid Search and Photometry Initiative) project. ASPIN is working in three main directions - search of new asteroids and comets with two 40-cm telescopes at New-Mexico (USA) and Siding Spring (Australia), follow up of new NEAs with 40-cm telescope at Khuraltogot (Mongolia) and research of physical properties of asteroids using photometry lightcurves of these celestial bodies. In 2015 it was obtained 278726 measurements and discovered 79 new objects including 7 NEAs (1 PHA) and 2 comets - P/2015 PD229 (ISON-Cameron) and C/2015 X4 (Elenin). Results of follow up observations were included in 68 MPC circulars. 5 campaigns of photometry observations were arranged with participation of 16 telescopes. It were obtained 320 lightcurves for 80 asteroids (including 69 NEAs) - 16 recently discovered objects, 2 Mars-crossers and 14 main-belt asteroids. It was measured or updated rotation periods of 20 NEAs including 9 small objects (˜300 m). 10 asteroids were observed under program of searching of the binary systems. 13 NEAs were observed in support of radar experiments. (1620) Geographos and 138852 (2000 WN10) asteroids were observed to investigated YORP-effect. The obtained results will be presented and perspectives of asteroid researches with ISON telescopes will be discussed.

  14. Collisional and Rotational Disruption of Asteroids

    NASA Astrophysics Data System (ADS)

    Walsh, Kevin J.; Michel, Patrick; Richardson, Derek C.

    2011-02-01

    Asteroids are leftover pieces from the era of planet formation that help us understand conditions in the early Solar System. Unlike larger planetary bodies that were subject to global thermal modification during and subsequent to their formation, these small bodies have kept at least some unmodified primordial material from the solar nebula. However, the structural properties of asteroids have been modified considerably since their formation. Thus, we can find among them a great variety of physical configurations and dynamical histories. In fact, with only a few possible exceptions, all asteroids have been modified or completely disrupted many times during the age of the Solar System. This picture is supported by data from space mission encounters with asteroids that show much diversity of shape, bulk density, surface morphology, and other features. Moreover, the gravitational attraction of these bodies is so small that some physical processes occur in a manner far removed from our common experience on Earth. Thus, each visit to a small body has generated as many questions as it has answered. In this review we discuss the current state of research into asteroid disruption processes, focusing on collisional and rotational mechanisms. We find that recent advances in modeling catastrophic disruption by collisions have provided important insights into asteroid internal structures and a deeper understanding of asteroid families. Rotational disruption, by tidal encounters or thermal effects, is responsible for altering many smaller asteroids, and is at the origin of many binary asteroids and oddly shaped bodies.

  15. Stochastic YORP On Real Asteroid Shapes

    NASA Astrophysics Data System (ADS)

    McMahon, Jay W.

    2015-05-01

    Since its theoretical foundation and subsequent observational verification, the YORP effect has been understood to be a fundamental process that controls the evolution of small asteroids in the inner solar system. In particular, the coupling of the YORP and Yarkovsky effects are hypothesized to be largely responsible for the transport of asteroids from the main belt to the inner solar system populations. Furthermore, the YORP effect is thought to lead to rotational fission of small asteroids, which leads to the creation of multiple asteroid systems, contact binary asteroids, and asteroid pairs. However recent studies have called into question the ability of YORP to produce these results. In particular, the high sensitivity of the YORP coefficients to variations in the shape of an asteroid, combined with the possibility of a changing shape due to YORP accelerated spin rates can combine to create a stochastic YORP coefficient which can arrest or change the evolution of a small asteroid's spin state. In this talk, initial results are presented from new simulations which comprehensively model the stochastic YORP process. Shape change is governed by the surface slopes on radar based asteroid shape models, where the highest slope regions change first. The investigation of the modification of YORP coefficients and subsequent spin state evolution as a result of this dynamically influenced shape change is presented and discussed.

  16. Space- and Ground-Based Observations of Exceptionally Young Asteroids

    NASA Astrophysics Data System (ADS)

    Tamblyn, P. M.; Merline, W. J.; Chapman, C. R.; Nesvorný, D.; Durda, D. D.

    2004-12-01

    We provide an overview and progress report on a suite of observations of very young asteroids. Three asteroid groups were previously identified through dynamical back integration as having arisen from very recent (<10 Myr) asteroid collisions (Nesvorný et al. 2002, Nature 417, 720; 2003 ApJ 591, 486). Hence these asteroid families provide an opportunity to probe the properties of the fragments of asteroid collisions before their characteristics have been masked by the aging and dynamical effects that dominate the observable properties of older asteroids. With a variety of observational programs, we aim to measure characteristics critical for comparison with hydrodynamical models of asteroid collisions. First, with a large Hubble Snapshot survey, we are testing if binaries are more prevalent among the young asteroids. This might be expected because ejection of mutually bound pairs is one mechanism for binary formation. Although our observed samples are small, we have discovered two new binaries among our control sample of old asteroids and none among the young asteroids sampled. We are extending the sample with ground-based Adaptive Optics at VLT, Gemini-N, Keck, and IRTF. In another ground-based experiment, we are measuring the lightcurve amplitudes and spin periods of these young asteroids for eventual comparison with simulations of asteroid breakup (e.g. Durda et al. 2004 Icarus 170, 243). Finally, with a Spitzer program, we are measuring the sizes and albedos of some of these young asteroids. This will immediately test if albedo is correlated with size or age, and provide the calibration for a ground-based determination of the size distribution. Together with the spin and shape information from lightcurves, these data will also further constrain the measurement of the Yarkovsky effect on main belt asteroids recently presented by Nesvorný & Bottke 2004 (Icarus, 170, 324).

  17. Asteroids IV

    NASA Astrophysics Data System (ADS)

    Michel, Patrick; DeMeo, Francesca E.; Bottke, William F.

    Asteroids are fascinating worlds. Considered the building blocks of our planets, many of the authors of this book have devoted their scientific careers to exploring them with the tools of our trade: ground- and spacebased observations, in situ space missions, and studies that run the gamut from theoretical modeling efforts to laboratory work. Like fossils for paleontologists, or DNA for geneticists, they allow us to construct a veritable time machine and provide us with tantalizing glimpses of the earliest nature of our solar system. By investigating them, we can probe what our home system was like before life or even the planets existed. The origin and evolution of life on our planet is also intertwined with asteroids in a different way. It is believed that impacts on the primordial Earth may have delivered the basic components for life, with biology favoring attributes that could more easily survive the aftermath of such energetic events. In this fashion, asteroids may have banished many probable avenues for life to relative obscurity. Similarly, they may have also prevented our biosphere from becoming more complex until more recent eras. The full tale of asteroid impacts on the history of our world, and how human life managed to emerge from myriad possibilities, has yet to be fully told. The hazard posed by asteroid impacts to our civilization is low but singular. The design of efficient mitigation strategies strongly relies on asteroid detection by our ground- and spacebased surveys as well as knowledge of their physical properties. A more positive motivation for asteroid discovery is that the proximity of some asteroids to Earth may allow future astronauts to harvest their water and rare mineral resources for use in exploration. A key goal of asteroid science is therefore to learn how humans and robotic probes can interact with asteroids (and extract their materials) in an efficient way. We expect that these adventures may be commonplace in the future

  18. Planetary geology: Impact processes on asteroids

    NASA Technical Reports Server (NTRS)

    Chapman, C. R.; Davis, D. R.; Greenberg, R.; Weidenschilling, S. J.

    1982-01-01

    The fundamental geological and geophysical properties of asteroids were studied by theoretical and simulation studies of their collisional evolution. Numerical simulations incorporating realistic physical models were developed to study the collisional evolution of hypothetical asteroid populations over the age of the solar system. Ideas and models are constrained by the observed distributions of sizes, shapes, and spin rates in the asteroid belt, by properties of Hirayama families, and by experimental studies of cratering and collisional phenomena. It is suggested that many asteroids are gravitationally-bound "rubble piles.' Those that rotate rapidly may have nonspherical quasi-equilibrium shapes, such as ellipsoids or binaries. Through comparison of models with astronomical data, physical properties of these asteroids (including bulk density) are determined, and physical processes that have operated in the solar system in primordial and subsequent epochs are studied.

  19. Radar Observations of Asteroids

    NASA Astrophysics Data System (ADS)

    Ostro, S. J.

    2003-05-01

    During the past 25 years, radar investigations have provided otherwise unavailable information about the physical and dynamical properties of more than 200 asteroids. Measurements of the distribution of echo power in time delay and Doppler frequency provide two-dimensional images with spatial resolution as fine as a decameter. Sequences of delay-Doppler images can be used to produce geologically detailed three-dimensional models, to define the rotation state precisely, to constrain the internal density distribution, and to estimate the trajectory of the object's center of mass. Radar wavelengths (4 to 13 cm) and the observer's control of transmitted and received polarizations make the observations sensitive to near-surface bulk density and macroscopic structure. Since delay-Doppler positional measurements are orthogonal to optical angle measurements and typically have much finer fractional precision, they are powerful for refining orbits and prediction ephemerides. Radar astrometry can add decades or centuries to the interval over which an asteroid's close Earth approaches can accurately be predicted and can significantly refine collision probability estimates based on optical astrometry alone. In the highly unlikely case that a small body is on course for an Earth collision in this century, radar reconnaissance would almost immediately distinguish between an impact trajectory and a near miss and would dramatically reduce the difficulty and cost of any effort to prevent the collision. The sizes and rotation periods of radar-detected asteroids span more than four orders of magnitude. These observations have revealed both stony and metallic objects, elongated and nonconvex shapes as well as nearly featureless spheroids, small-scale morphology ranging from smoother than the lunar regolith to rougher than the rockiest terrain on Mars, craters and diverse linear structures, non-principal-axis spin states, contact binaries, and binary systems.

  20. Radar Investigations of Asteroids

    NASA Astrophysics Data System (ADS)

    Ostro, S.

    2004-05-01

    Radar investigations have provided otherwise unavailable information about the physical and dynamical properties of about 230 asteroids. Measurements of the distribution of echo power in time delay (range) and Doppler frequency (line-of-sight velocity) provide two-dimensional images with spatial resolution as fine as a decameter. Sequences of delay-Doppler images can be used to produce geologically detailed three-dimensional models, to define the rotation state precisely, to constrain the internal density distribution, and to estimate the trajectory of the object's center of mass. Radar wavelengths (4 to 13 cm) and the observer's control of transmitted and received polarizations make the observations sensitive to near-surface bulk density and macroscopic structure. Since delay-Doppler measurements are orthogonal to optical angle measurements and typically have much finer fractional precision, they are powerful for refining orbits and prediction ephemerides. Such astrometric measurements can add decades or centuries to the interval over which an asteroid's close Earth approaches can accurately be predicted and can significantly refine collision probability estimates based on optical astrometry alone. In the highly unlikely case that a small body is on course for an Earth collision in this century, radar reconnaissance would almost immediately distinguish between an impact trajectory and a near miss and would dramatically reduce the difficulty and cost of any effort to prevent the collision. The sizes and rotation periods of radar-detected asteroids span more than four orders of magnitude. The observations have revealed both stony and metallic objects, elongated and nonconvex shapes as well as nearly featureless spheroids, small-scale morphology ranging from smoother than the lunar regolith to rougher than the rockiest terrain on Mars, craters and diverse linear structures, non-principal-axis spin states, contact binaries, and binary systems.

  1. Distortion effects in Trojan Horse applications

    SciTech Connect

    Pizzone, R. G.; La Cognata, M.; Lamia, L.; Mukhamedzhanov, A. M.; Blokhintsev, L. D.; Irgaziev, B.; Bertulani, C. A.; Spitaleri, C.

    2012-11-20

    Deuteron induced quasi-free scattering and reactions have been extensively investigated in the past few decades. This was done not only for nuclear structure and processes study but also for the important astrophysical implication (Trojan Horse Method, THM). In particular the width of the neutron momentum distribution in deuteron will be studied as a function of the transferred momentum. The same will be done for other nuclides of possible use as Trojan Horse particles. Trojan horse method applications will also be discussed because the momentum distribution of the spectator particle inside the Trojan horse nucleus is a necessary input for this method. The impact of the width (FWHM) variation on the extraction of the astrophysical S(E)-factor is discussed.

  2. Asteroid spin-up fission systems

    NASA Astrophysics Data System (ADS)

    Pravec, P.

    2014-07-01

    Among asteroids smaller than about 15 km in diameter, there is a population of binary and multiple asteroid systems that show characteristics strongly suggesting their formation by spin-up fission. I will review the current observational data we have on the systems and compare them with predictions from theories of formation of asteroid systems. I will show that the best explanation of their observed properties is provided by the theory of fission of cohesionless (rubble-pile) asteroids spun up to the critical spin frequency by the YORP effect. Observed asteroid systems are of two kinds: bound and unbound. Bound asteroid systems typically consist of a larger primary and one or two smaller satellites. Unbound systems consist of two asteroids orbiting the Sun on highly similar orbits, again with one being typically larger (primary) and the other being smaller (secondary). These two groups are not exclusive; there exist systems with one or two bound and an unbound secondary. Our current sample consists of 133 bound asteroid systems (binaries or triples) with primary sizes between 0.12 and 13 km and of 178 asteroid pairs with similar primary sizes. Bound systems have been observed in heliocentric orbits from near the Earth to the outer main belt, while asteroid pairs are recognizable only in the main belt where their orbits are only slowly dispersed so the pairs can be identified for up to 2 Myr after formation. The leading observational techniques for discovery and characterization of asteroid systems are radar imagery (for near-Earth asteroid systems) and lightcurve photometry (for main-belt ones). The observed characteristics of asteroid systems suggesting their formation by rotational fission of parent rubble-pile asteroids after being spun up by the YORP effect are as follows. The angular momentum content of binary asteroids is close to critical. The orientations of satellite orbits are non-random; the orbital poles concentrate near the obliquities of 0 and 180

  3. A Carefully Characterized and Tracked Trans-Neptunian Survey: The Size distribution of the Plutinos and the Number of Neptunian Trojans

    NASA Astrophysics Data System (ADS)

    Alexandersen, Mike; Gladman, Brett; Kavelaars, J. J.; Petit, Jean-Marc; Gwyn, Stephen D. J.; Shankman, Cory J.; Pike, Rosemary E.

    2016-11-01

    The trans-Neptunian objects (TNOs) preserve evidence of planet building processes in their orbital and size distributions. While all populations show steep size distributions for large objects, a relative deficit of Neptunian trojans and scattering objects with diameters of D < 100 km has been detected. We investigated this deficit with a 32 square degree survey, in which we detected 77 TNOs that are brighter than a limiting r-band magnitude of 24.6. Our plutino sample (18 objects in 3:2 mean-motion resonance with Neptune) shows a deficit of D < 100 km objects, rejecting a single power-law size distribution at >99% confidence. Combining our survey with the Canada–France Ecliptic Plane Survey, we perform a detailed analysis of the allowable parameters for the plutino size distribution, including knees and divots. We surmise the existence of 9000 ± 3000 plutinos with an absolute magnitude of H r ≤ 8.66 and {37000}-10000+12000 with H r ≤ 10.0 (95% confidence). Our survey also discovered one temporary Uranian trojan, one temporary Neptunian trojan, and one stable Neptunian trojan, for which we estimate populations of {110}-100+500, {210}-200+900, and {150}-140+600 with H r ≤ 10.0, respectively. All three populations are thus less numerous than the main belt asteroids (592 asteroids with H r ≤ 10.0). With such population sizes, the temporary Neptunian trojans cannot be previously stable trojans diffusing out of the resonance now; they must be recently captured Centaurs or scattering objects. As the bias against the detection of objects grows with larger semimajor axes, our discovery of three 3:1 resonators and one 4:1 resonator adds to the growing evidence that the high-order resonances are far more populated than is typically predicted.

  4. The Asteroid Impact and Deflection Assessment Mission and its Potential Contributions to Human Exploration of Asteroids

    NASA Technical Reports Server (NTRS)

    Abell, Paul A.; Rivkin, Andy S.

    2014-01-01

    The joint ESA and NASA Asteroid Impact and Deflection Assessment (AIDA) mission will directly address aspects of NASA's Asteroid Initiative and will contribute to future human exploration. The NASA Asteroid Initiative is comprised of two major components: the Grand Challenge and the Asteroid Mission. The first component, the Grand Challenge, focuses on protecting Earth's population from asteroid impacts by detecting potentially hazardous objects with enough warning time to either prevent them from impacting the planet, or to implement civil defense procedures. The Asteroid Mission, involves sending astronauts to study and sample a near-Earth asteroid (NEA) prior to conducting exploration missions of the Martian system, which includes Phobos and Deimos. AIDA's primary objective is to demonstrate a kinetic impact deflection and characterize the binary NEA Didymos. The science and technical data obtained from AIDA will aid in the planning of future human exploration missions to NEAs and other small bodies. The dual robotic missions of AIDA, ESA's Asteroid Impact Monitor (AIM) and NASA's Double Asteroid Redirection Test (DART), will provide a great deal of technical and engineering data on spacecraft operations for future human space exploration while conducting in-depth scientific examinations of the binary target Didymos both prior to and after the kinetic impact demonstration. The knowledge gained from this mission will help identify asteroidal physical properties in order to maximize operational efficiency and reduce mission risk for future small body missions. The AIDA data will help fill crucial strategic knowledge gaps concerning asteroid physical characteristics that are relevant for human exploration considerations at similar small body destinations.

  5. Optical Spectroscopy of Unbound Asteroid Pairs

    NASA Astrophysics Data System (ADS)

    Duddy, Samuel; Lowry, S. C.; Christou, A.; Wolters, S. D.; Snodgrass, C.; Fitzsimmons, A.; Deller, J. F.; Hainaut, O. R.; Rozitis, B.; Weissman, P. R.; Green, S. F.

    2012-10-01

    The recently discovered unbound asteroid pairs have been suggested to be the result of the decoupling of binary asteroids formed either through collision processes or, more likely, rotational fission of a rubble-pile asteroid after spin-up (Vokrouhlicky et al. 2008, AJ 136, 280; Pravec et al., 2010, Nature, 466, 1085). Much of the evidence for linkage of the asteroids in each pair relies solely on the backwards integrations of their orbits. We report new results from our continuing spectroscopic survey of the unbound asteroid pairs, including the youngest known pair, (6070) Rhineland - (54827) 2001 NQ8. The survey goal is to determine whether the asteroids in each unbound pair have similar spectra and therefore composition, expected if they have formed from a common parent body. Low-resolution spectroscopy covering the range 0.4-0.95 microns was conducted using the 3.6m ESO NTT+EFOSC2 during 2011-2012 and the 4.2m WHT+ACAM. We have attempted to maintain a high level of consistency between the observations of the components in each pair to ensure that differences in the asteroid spectra are not the result of the observing method or data reduction, but purely caused by compositional differences. Our WHT data indicates that the asteroids of unbound pair 17198 - 229056 exhibit different spectra and have been assigned different taxonomies, A and R respectively. Initial analysis of our data from the NTT suggests that the asteroids in unbound pairs 6070 - 54827 and 38707 - 32957 are likely silicate-dominated asteroids. The components of pair 23998 - 205383 are potentially X-type asteroids. We present final taxonomic classifications and the likelihood of spectral similarity in each pair.

  6. Asteroid polarimetry

    NASA Astrophysics Data System (ADS)

    Gil-Hutton, R.

    2014-07-01

    The discovery of the polarization of moonlight by Arago in 1811 was the first step in the polarization studies of atmosphereless bodies. In the last 20 years, the optical polarimetry of Solar System bodies has had a fast development due to the availability of new equipment, and the efforts of several research groups to study different objects and to increase the database of polarimetric observations. These efforts led to the discovery of objects with anomalous polarimetric properties and the polarimetric characterization of many taxonomic types. Since several theoretical aspects of the polarimetric phenomena will be addressed in other talks, I will present here the recent achievements in asteroid polarimetry from the observational point of view and the role of polarimetry in the overall scenario of asteroid science.

  7. Composition of Irradiation Residue from Jupiter Trojan Laboratory Simulations

    NASA Astrophysics Data System (ADS)

    Poston, Michael; Mahjoub, Ahmed; Blacksberg, Jordana; Brown, Michael E.; Carlson, Robert W.; Ehlmann, Bethany; Eiler, John; Hand, Kevin P.; Hodyss, Robert; Wong, Ian

    2016-10-01

    Today's Jupiter Trojan asteroids may have originated in the Kuiper Belt (eg. Morbidelli et al. Nature 2005, Nesvorny et al. ApJ 2013) and migrated to capture at their present locations. If this is the case, it is expected that their surfaces will contain chemical traces of this history. Our work broadly considers laboratory simulations of this history. In this work we report on the refractory residue left behind when irradiated mixed ice samples were brought to Earth-normal conditions and removed from the vacuum system. Ices that will be discussed include a 3:3:3:1 mixture of H2S:NH3:CH3OH:H2O and a 3:3:1 mixture of NH3:CH3OH:H2O. After deposition at 50K, the ices were irradiated with a beam of 10 keV electrons to form a processed crust mixed with unreacted ices. The films were then warmed to 142K under irradiation over several days. After stopping irradiation, the mixtures were slowly heated through the desorption temperatures of the unreacted ices (about 150-180K), leaving only more-stable compounds behind, and up to room temperature. Some of the reaction products were seen to desorb during heating to room temperature, while a significant amount remained as a refractory residue. After backfilling the vacuum system with nitrogen gas, residues were analyzed by Fourier Transform Infrared Spectroscopy, Secondary Ion Mass Spectrometry, and Gas Chromatograph Mass Spectrometry. Results indicate a complex chemistry including aliphatic and aromatic hydrocarbons, and nitrogen and sulfur-containing organics. Notably, when sulfur is not present, a number of nitrogen-containing organic candidates are identified, however, in the mixtures containing sulfur, sulfur-containing compounds appear to dominate the chemistry. While these experiments were conducted with Trojan asteroids in mind, the results are also relevant to comets and other cold locations in the solar system that have experienced large swings in temperature.This work has been supported by the Keck Institute for

  8. Asteroids 87887 - 415992: the youngest known asteroid pair?

    NASA Astrophysics Data System (ADS)

    Žižka, J.; Galád, A.; Vokrouhlický, D.; Pravec, P.; Kušnirák, P.; Hornoch, K.

    2016-10-01

    Context. Pairs of asteroids, that is, couples of single bodies on tightly similar heliocentric orbits, were recently postulated as a new category of objects in the solar system. They are believed to be close twins to binary and multiple systems. Aims: Ages of the known pairs range from about 15 kyr to nearly a million years. Beyond the upper limit, the pairs disperse in the background population of asteroids and become difficult to detect. Below the lower limit, the pairs should be easily recognizable if they exist and are discovered by surveys. Using the available data, we analyze the possible existence of very young asteroid pairs with clearly proven ages ≤ 10 kyr. Methods: We searched for candidate very young asteroid pairs in the current catalog of asteroid orbits. After a preliminary analysis, we selected the most promising case of the small asteroids (87887) 2000 SS286 and (415992) 2002 AT49. We collected photometric observations to determine their rotation periods and absolute magnitudes. Results: The rotation period of (87887) 2000 SS286 is 5.7773 ± 0.0004 h. Analysis of the data for (415992) 2002 AT49 indicates as the most probable period 2.6366 ± 0.0003 h, but other solutions are still possible. The composite light curves of the two asteroids have very low amplitudes, 0.22 and 0.12 mag, suggesting roundish shapes. Our observations also allow us to determine the absolute magnitude in R band HR = 14.99 ± 0.04 and HR = 16.24 ± 0.03 for the primary and secondary components. A transformation to the visible band provides H = 15.44 ± 0.05 and H = 16.69 ± 0.04. These two asteroids experienced a very close encounter, probably a formation event, some 7.4 ± 0.3 kyr ago. The formal extension of our numerical runs backward in time reveal that these close encounters may have continued, starting from ≃ 45 kyr ago. However, based on tests using synthetic fission events, we argue that the older age solutions might be the true solution only at ≃ (10-15)% level

  9. Colors of dynamically associated asteroid pairs

    NASA Astrophysics Data System (ADS)

    Moskovitz, Nicholas A.

    2012-09-01

    Recent dynamical studies have identified pairs of asteroids that reside in nearly identical heliocentric orbits. Possible formation scenarios for these systems include dissociation of binary asteroids, collisional disruption of a single parent body, or spin-up and rotational fission of a rubble-pile. Aside from detailed dynamical analyses and measurement of rotational light curves, little work has been done to investigate the colors or spectra of these unusual objects. A photometric and spectroscopic survey was conducted to determine the reflectance properties of asteroid pairs. New observations were obtained for a total of 34 individual asteroids. Additional photometric measurements were retrieved from the Sloan Digital Sky Survey Moving Object Catalog. Colors or spectra for a total of 42 pair components are presented here. The main findings of this work are: (1) the components in the observed pair systems have the same colors within the uncertainties of this survey, and (2) the color distribution of asteroid pairs appears indistinguishable from that of all Main Belt asteroids. These findings support a scenario of pair formation from a common progenitor and suggest that pair formation is likely a compositionally independent process. In agreement with previous studies, this is most consistent with an origin via binary disruption and/or rotational fission.

  10. Visible and infrared investigations of planet-crossing asteroids and outer solar system objects

    NASA Technical Reports Server (NTRS)

    Tholen, David J.

    1991-01-01

    The project is supporting lightcurve photometry, colorimetry, thermal radiometry, and astrometry of selected asteroids. Targets include the planet-crossing population, particularly Earth approachers, which are believed to be the immediate source of terrestrial meteorites, future spacecraft targets, and those objects in the outer belt, primarily the Hilda and Trojan populations, that are dynamically isolated from the main asteroid belt. Goals include the determination of population statistics for the planet-crossing objects, the characterization of spacecraft targets to assist in encounter planning and subsequent interpretation of the data, a comparison of the collisional evolution of dynamically isolated Hilda and Trojan populations with the main belt, and the determination of the mechanism driving the activity of the distant object 2060 Chiron.

  11. AIDA: Asteroid Impact and Deflection Assessment

    NASA Astrophysics Data System (ADS)

    Michel, Patrick; Cheng, A.; Galvez, A.; Reed, C.; Carnelli, I.; Abell, P.; Ulamec, S.; Rivkin, A.; Biele, J.; Murdoch, N.

    2015-03-01

    AIDA (Asteroid Impact and Deflection Assessment) is a project of a joint mission demonstration of asteroid deflection and characterisation of the kinetic impact effects. It involves the Johns Hopkins Applied Physics Laboratory (with support from members of NASA centers including Goddard Space Flight Center, Johnson Space Center, and the Jet Propulsion Laboratory), and the European Space Agency (with support from members of the french CNRS/Cte dAzur Observatory and the german DLR). This assessment will be done using a binary asteroid target. AIDA consists of two independent but mutually supporting mission concepts, one of which is the asteroid kinetic impactor and the other is the characterisation spacecraft. The objective and status of the project will be presented.

  12. An intestinal Trojan horse for gene delivery

    NASA Astrophysics Data System (ADS)

    Peng, Haisheng; Wang, Chao; Xu, Xiaoyang; Yu, Chenxu; Wang, Qun

    2015-02-01

    The intestinal epithelium forms an essential element of the mucosal barrier and plays a critical role in the pathophysiological response to different enteric disorders and diseases. As a major enteric dysfunction of the intestinal tract, inflammatory bowel disease is a genetic disease which results from the inappropriate and exaggerated mucosal immune response to the normal constituents in the mucosal microbiota environment. An intestine targeted drug delivery system has unique advantages in the treatment of inflammatory bowel disease. As a new concept in drug delivery, the Trojan horse system with the synergy of nanotechnology and host cells can achieve better therapeutic efficacy in specific diseases. Here, we demonstrated the feasibility of encapsulating DNA-functionalized gold nanoparticles into primary isolated intestinal stem cells to form an intestinal Trojan horse for gene regulation therapy of inflammatory bowel disease. This proof-of-concept intestinal Trojan horse will have a wide variety of applications in the diagnosis and therapy of enteric disorders and diseases.

  13. Asteroid families

    NASA Technical Reports Server (NTRS)

    Williams, James G.

    1991-01-01

    More than 100 asteroid families are presented in Williams. Several examples of cratering events are known including family numbers 150, 162, 169, and 189. These are recognizable as many small fragments adjacent to and to one side (in three dimensions) of a much larger cratered body. Family numbers 138 and 140 are adjacent in proper element space. In population they are an intermediate step between the long recognizable families and the more frequent less populated families. Family number 164 is the fifth most populous family in the belt. All members are faint and nothing is known of the physical properties.

  14. Stability of binaries. Part 1: Rigid binaries

    NASA Astrophysics Data System (ADS)

    Sharma, Ishan

    2015-09-01

    We consider the stability of binary asteroids whose members are possibly granular aggregates held together by self-gravity alone. A binary is said to be stable whenever each member is orbitally and structurally stable to both orbital and structural perturbations. To this end, we extend the stability test for rotating granular aggregates introduced by Sharma (Sharma, I. [2012]. J. Fluid Mech., 708, 71-99; Sharma, I. [2013]. Icarus, 223, 367-382; Sharma, I. [2014]. Icarus, 229, 278-294) to the case of binary systems comprised of rubble members. In part I, we specialize to the case of a binary with rigid members subjected to full three-dimensional perturbations. Finally, we employ the stability test to critically appraise shape models of four suspected binary systems, viz., 216 Kleopatra, 25143 Itokawa, 624 Hektor and 90 Antiope.

  15. Hektor - an exceptional D-type family among Jovian Trojans

    NASA Astrophysics Data System (ADS)

    Rozehnal, J.; Brož, M.; Nesvorný, D.; Durda, D. D.; Walsh, K.; Richardson, D. C.; Asphaug, E.

    2016-11-01

    In this work, we analyse Jovian Trojans in the space of suitable resonant elements and we identify clusters of possible collisional origin by two independent methods: the hierarchical clustering and a so-called randombox. Compared to our previous work, we study a twice larger sample. Apart from Eurybates, Ennomos and 1996 RJ families, we have found three more clusters - namely families around asteroids (20961) Arkesilaos, (624) Hektor in the L4 libration zone and (247341) 2001 UV209 in L5. The families fulfill our stringent criteria, i.e. a high statistical significance, an albedo homogeneity and a steeper size-frequency distribution than that of background. In order to understand their nature, we simulate their long term collisional evolution with the Boulder code and dynamical evolution using a modified SWIFT integrator. Within the framework of our evolutionary model, we were able to constrain the age of the Hektor family to be either 1-4 Gyr or, less likely, 0.1-2.5 Gyr, depending on initial impact geometry. Since (624) Hektor itself seems to be a bilobed-shape body with a satellite, i.e. an exceptional object, we address its association with the D-type family and we demonstrate that the moon and family could be created during a single impact event. We simulated the cratering event using a smoothed particle hydrodynamics. This is also the first case of a family associated with a D-type parent body.

  16. Asteroid Redirect Mission: Robotic Segment

    NASA Video Gallery

    This concept animation illustrates the robotic segment of NASA's Asteroid Redirect Mission. The Asteroid Redirect Vehicle, powered by solar electric propulsion, travels to a large asteroid to robot...

  17. Chang'e-2 spacecraft observations of asteroid 4179 Toutatis

    NASA Astrophysics Data System (ADS)

    Ji, Jianghui; Jiang, Yun; Zhao, Yuhui; Wang, Su; Yu, Liangliang

    2016-01-01

    On 13 December 2012, Chang'e-2 completed a successful flyby of the near-Earth asteroid 4179 Toutatis at a closest distance of 770 meters from the asteroid's surface. The observations show that Toutatis has an irregular surface and its shape resembles a ginger-root of a smaller lobe (head) and a larger lobe (body). Such bilobate shape is indicative of a contact binary origin for Toutatis. In addition, the high-resolution images better than 3 meters provide a number of new discoveries about this asteroid, such as an 800-meter depression at the end of the large lobe, a sharply perpendicular silhouette near the neck region, boulders, indicating that Toutatis is probably a rubble-pile asteroid. Chang'e-2 observations have significantly revealed new insights into the geological features and the formation and evolution of this asteroid. In final, we brief the future Chinese asteroid mission concept.

  18. Observations of Planet Crossing Asteroids

    NASA Technical Reports Server (NTRS)

    Tholen, David J.; Whiteley, Robert J.; Lambert, Joy; Connelley, Michael; Salyk, Colette

    2002-01-01

    The goals of this research were the physical and dynamical characterization of planet crossing asteroids (Earth crossers, Mars crossers, Centaurs, and Pluto crossers, meaning trans-Neptunian objects), including colorimetry, rotational studies, and astrometry. Highlights are listed as follows: 1) Produced one doctoral dissertation (R. J. Whiteley, A Compositional and Dynamical Survey of the Near-Earth Asteroids). A key result is the fraction of Q-type asteroids among the near-Earth population was found to be about one-third; 2) Had prediscovery image showing the binary nature of trans-Neptunian object 1998 WW31, which is the first TNO to have a satellite found in orbit around it; 3) Discovery of shortest known rotation period for any asteroid (2000 D08, rotation period 78 seconds); it is just one of several fast-rotating small asteroids observed during the course of this project; 4) Discovery of a Centaur asteroid (1998 QM107) with, at the time, the smallest known orbital eccentricity among the Centaurs (0.13) and nearly in a 1:1 resonance with Uranus (semimajor axis of 19.9 AU); 5) Discovery of Apollo-type asteroid 1999 OW3, with a surprisingly bright absolute magnitude of 14.6 (estimated diameter of 4.6 km), brightest Apollo found in that calendar year; 6) Discovery of Aten-type asteroid 2000 SG344, which has the highest cumulative Earth impact probability among the near-Earth asteroids and a very Earth-similar orbit; 7) Instrumental in repairing the orbit of a numbered near-Earth asteroid for which prediscovery observations had been mis-attributed to it (2000 VN2); 8) Second-opposition recovery of 30-meter diameter Apollo-type asteroid 1998 KY26 in early 2002 when it was at a favorable magnitude of 24.8; 9) Primary contributor of astrometric observations of the CONTOUR fragments to the CONTOUR project following the failure of the spacecraft s kick motor; and 10) Development of orbit and ephemeris computation code that handles short observational arcs

  19. (1173) Anchises - thermophysical and dynamical studies of a dynamically unstable Jovian Trojan

    NASA Astrophysics Data System (ADS)

    Horner, J.; Müller, T. G.; Lykawka, P. S.

    2012-07-01

    We have performed detailed thermophysical and dynamical modelling of the Jovian Trojan (1173) Anchises. Our results show that this is the most unusual object. By examining observational data of Anchises taken by IRAS, Akari and WISE at wavelengths between 11.5 and 60 μm, together with the variations in its optical light curve, we find that Anchises is most likely an elongated body, with an axis ratio, a/b, of around 1.4. This results in calculated best-fitting dimensions for Anchises of 170 × 121 × 121 km (or an equivalent diameter of 136 +18/-11 km). We find that the observations of Anchises are best fitted by the object having a retrograde sense of rotation, and an unusually high thermal inertia in the range 25-100 J m-2 s-0.5 K-1 (3σ confidence level). The geometric albedo of Anchises is found to be 0.027 (+0.006/-0.007). Anchises therefore has one of the highest published thermal inertias of any object larger than 100 km in diameter, at such large heliocentric distances, as well as being one of the lowest albedo objects ever observed. More observations (visual and thermal) are needed to see whether there is a link between the very shallow phase curve, with almost no opposition effect, and the derived thermal properties for this large Trojan asteroid. Our dynamical investigation of Anchises' orbit has revealed it to be dynamically unstable on time-scales of hundreds of millions of years, similar to the unstable Neptunian Trojans 2001 QR322 and 2008 LC18. Unlike those objects, however, we find that the dynamical stability of Anchises is not a function of its initial orbital elements, the result of the exceptional precision with which its orbit is known. Our results are the first to show that a Jovian Trojan is dynamically unstable, and add further weight to the idea that the planetary Trojans likely represent a significant ongoing contribution to the dynamically unstable Centaur population, the parents of the short-period comets. The observed instability

  20. A SYSTEMATIC SEARCH FOR TROJAN PLANETS IN THE KEPLER DATA

    SciTech Connect

    Janson, Markus

    2013-09-10

    Trojans are circumstellar bodies that reside in characteristic 1:1 orbital resonances with planets. While all the trojans in our solar system are small ({approx}<100 km), stable planet-size trojans may exist in extrasolar planetary systems, and the Kepler telescope constitutes a formidable tool to search for them. Here we report on a systematic search for extrasolar trojan companions to 2244 known Kepler Objects of Interest (KOIs), with epicyclic orbital characteristics similar to those of the Jovian trojan families. No convincing trojan candidates are found, despite a typical sensitivity down to Earth-size objects. This fact, however, cannot be used to stringently exclude the existence of trojans in this size range, since stable trojans need not necessarily share the same orbital plane as the planet, and thus may not transit. Following this reasoning, we note that if Earth-sized trojans exist at all, they are almost certainly both present and in principle detectable in the full set of Kepler data, although a very substantial computational effort would be required to detect them. Additionally, we also note that some of the existing KOIs could in principle be trojans themselves, with a primary planet orbiting outside of the transiting plane. A few examples are given for which this is a readily testable scenario.

  1. CAPTURE OF TROJANS BY JUMPING JUPITER

    SciTech Connect

    Nesvorny, David; Vokrouhlicky, David; Morbidelli, Alessandro

    2013-05-01

    Jupiter Trojans are thought to be survivors of a much larger population of planetesimals that existed in the planetary region when planets formed. They can provide important constraints on the mass and properties of the planetesimal disk, and its dispersal during planet migration. Here, we tested a possibility that the Trojans were captured during the early dynamical instability among the outer planets (aka the Nice model), when the semimajor axis of Jupiter was changing as a result of scattering encounters with an ice giant. The capture occurs in this model when Jupiter's orbit and its Lagrange points become radially displaced in a scattering event and fall into a region populated by planetesimals (that previously evolved from their natal transplanetary disk to {approx}5 AU during the instability). Our numerical simulations of the new capture model, hereafter jump capture, satisfactorily reproduce the orbital distribution of the Trojans and their total mass. The jump capture is potentially capable of explaining the observed asymmetry in the number of leading and trailing Trojans. We find that the capture probability is (6-8) Multiplication-Sign 10{sup -7} for each particle in the original transplanetary disk, implying that the disk contained (3-4) Multiplication-Sign 10{sup 7} planetesimals with absolute magnitude H < 9 (corresponding to diameter D = 80 km for a 7% albedo). The disk mass inferred from this work, M{sub disk} {approx} 14-28 M{sub Earth}, is consistent with the mass deduced from recent dynamical simulations of the planetary instability.

  2. Science Education as South Africa's Trojan Horse.

    ERIC Educational Resources Information Center

    Rogan, John M.; Gray, Brian V.

    1999-01-01

    Presents the story of one nongovernmental organization (NGO) and the role it played in reconceptualizing science education in South Africa. Describes the success of the Science Education Project (SEP) in confronting authoritarian practices of government organizations and those within its own ranks. Science education can become the Trojan horse of…

  3. Nuclear astrophysics and the Trojan Horse Method

    NASA Astrophysics Data System (ADS)

    Spitaleri, C.; La Cognata, M.; Lamia, L.; Mukhamedzhanov, A. M.; Pizzone, R. G.

    2016-04-01

    In this review, we discuss the new recent results of the Trojan Horse Method that is used to determine reaction rates for nuclear processes in several astrophysical scenarios. The theory behind this technique is shortly presented. This is followed by an overview of some new experiments that have been carried out using this indirect approach.

  4. Nuclear Astrophysics with the Trojan Horse Method

    NASA Astrophysics Data System (ADS)

    Tumino, A.; Spitaleri, C.; Lamia, L.; Pizzone, R. G.; Cherubini, S.; Gulino, M.; La Cognata, M.; Puglia, S. M. R.; Rapisarda, G. G.; Romano, S.; Sergi, M. L.; Spartá, R.

    2016-01-01

    The Trojan Horse Method (THM) represents the indirect path to determine the bare nucleus astrophysical S(E) factor for reactions between charged particles at astrophysical energies. This is done by measuring the quasi free cross section of a suitable three body process. The basic features of the THM will be presented together with some applications to demonstrate its practical use.

  5. 5 - 14 μm Spitzer spectra of the Themis and Veritas asteroid families

    NASA Astrophysics Data System (ADS)

    Landsman, Zoe A.; Licandro, Javier; Campins, Humberto; Ziffer, Julie; de Prá, Mario

    2016-01-01

    Spectroscopic studies of primitive asteroid families provide constraints on the composition of the solar nebula and the distribution of volatiles in the asteroid belt. Results from visible and near-infrared spectroscopy show diversity between primitive families. We aim to better constrain the composition of two primitive families with very different ages: Themis (~2.5 Gyr) and Veritas (~8 Myr). We analyzed 5 - 14 μm Spitzer Space Telescope spectra of 11 Themis asteroids and nine Veritas asteroids, for a total of 20 asteroids. We report the presence of a broad 10-μm emission feature, attributed to a layer of fine-grained silicates, in the spectra of all 11 Themis asteroids and six of nine Veritas asteroids in our sample. Spectral contrast in statistically significant detections of the 10-μm feature ranges from 1% ± 0.1% to 8.5% ± 0.9%. Comparison with the spectra of primitive meteorites (McAdam et al. 2015, Icarus, 245, 320) suggests asteroids in both families are similar to meteorites with lower abundances of phyllosilicates. We used the Near-Earth Asteroid Thermal Model to derive diameters, beaming parameters and albedos for our sample. Asteroids in both families have beaming parameters near unity and low to moderate albedos. We find that contrast of the silicate emission feature is not correlated with asteroid diameter; however, higher 10-μm contrast may be associated with flatter spectral slopes in the near-infrared. The spectra of both families are consistent with icy bodies with some amount of fine-grained silicates, but with coarser grains or denser surface structure than Trojan asteroids and comets. The range of spectral contrast of the 10-μm emission feature within each family suggests diversity in regolith porosity and/or grain size.

  6. NEOWISE: The distribution of the large primitive asteroids

    NASA Astrophysics Data System (ADS)

    Grav, T.; Mainzer, A.; Bauer, J.; Masiero, J.; Nugent, C.; Stevenson, R.; Sonnett, S.

    2014-07-01

    The Wide-field Infrared Survey Explorer (WISE) is a NASA Medium-class Explorer mission that surveyed the entire sky in four infrared wavelengths at 3.4, 4.6, 12, and 22 microns (denoted W1, W2, W3, and W4, respectively) [1,2]. The solar-system specific portion of the WISE project, known as NEOWISE, collected more than 2 million observations of more than 158,000 asteroids, including near-Earth objects, main-belt asteroids, comets, Hildas, Jovian Trojans, Centaurs, and scattered-disk objects [3]. The methods used for data extraction and thermal modeling have been extensively detailed in [3--6]. The resulting physical properties have been reported in a series of papers [3--13]. In [6] and [9], it was shown that the visible albedo in the V band and the near-infrared albedo in the W1 and W2 bands can be used to taxonomically classify a significant number of the largest members of the Hilda and Jovian Trojan populations (see Figure 1). This allows for the study of the distribution of primitive asteroids in the region between the main asteroid and the giant planets, down to sizes where the populations are completely sampled. Figure 2 shows that for the Hilda population, where the sample is observationally complete to about 40 km, the C/P types dominated over the D types at the larger sizes. However, for the smaller sizes, the D types become significantly more numerous. For the Jovian Trojan population, for which the sample is observationally complete to about 50 km, the D types are slightly more numerous at the largest sizes. As smaller sizes are included, the D types become more dominant, with more than 80 % of the objects larger than 50 km having this taxonomic type. We have now extended the study to include thermal fits and taxonomic classification of the outer main belt, Cybeles, irregular satellites of Jupiter and Saturn, and the Centaur population [13], and will present the results of this work. The distribution of primitive asteroids in the different populations

  7. Spin Rate Distribution of Small Asteroids Shaped by YORP Effect

    NASA Astrophysics Data System (ADS)

    Pravec, Petr

    2008-09-01

    We studied a distribution of spin rates of main belt/Mars crossing (MB/MC) asteroids with diameters 3-15 km using data obtained within the Photometric Survey of Asynchronous Binary Asteroids (Pravec et al. 2008). We found that the spin distribution of the small asteroids is uniform in the range from f = 1 to 9.5 d-1, and there is an excess of slow rotators with f < 1 d-1. The observed distribution appears to be controlled by the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect. The magnitude of the excess of slow rotators is related to the residence time of slowed down asteroids in the excess and the rate of spin rate change outside the excess. We estimated a median YORP spin rate change of 0.022 d-1/Myr for asteroids in our sample (i.e., a median time in which the spin rate changes by 1 d-1 is 45 Myr), thus the residence time of slowed down asteroids in the excess is 110 Myr. The spin rate distribution of near-Earth asteroids (NEAs) with sizes in the range 0.2-3 km ( 5-times smaller in median diameter than the MB/MC asteroids sample) shows a similar excess of slow rotators, but there is also a concentration of NEAs at fast spin rates with f = 9-10 d-1. The concentration at fast spin rates is correlated with a narrower distribution of spin rates of primaries of binary systems among NEAs; the difference may be due to the apparently more evolved population of binaries among MB/MC asteroids. Reference: Pravec, P., and 30 colleagues, 2008. Spin rate distribution of small asteroids. Icarus, in press. DOI: http://dx.doi.org/10.1016/j.icarus.2008.05.012

  8. Formation of asteroid pairs by rotational fission.

    PubMed

    Pravec, P; Vokrouhlický, D; Polishook, D; Scheeres, D J; Harris, A W; Galád, A; Vaduvescu, O; Pozo, F; Barr, A; Longa, P; Vachier, F; Colas, F; Pray, D P; Pollock, J; Reichart, D; Ivarsen, K; Haislip, J; Lacluyze, A; Kusnirák, P; Henych, T; Marchis, F; Macomber, B; Jacobson, S A; Krugly, Yu N; Sergeev, A V; Leroy, A

    2010-08-26

    Pairs of asteroids sharing similar heliocentric orbits, but not bound together, were found recently. Backward integrations of their orbits indicated that they separated gently with low relative velocities, but did not provide additional insight into their formation mechanism. A previously hypothesized rotational fission process may explain their formation-critical predictions are that the mass ratios are less than about 0.2 and, as the mass ratio approaches this upper limit, the spin period of the larger body becomes long. Here we report photometric observations of a sample of asteroid pairs, revealing that the primaries of pairs with mass ratios much less than 0.2 rotate rapidly, near their critical fission frequency. As the mass ratio approaches 0.2, the primary period grows long. This occurs as the total energy of the system approaches zero, requiring the asteroid pair to extract an increasing fraction of energy from the primary's spin in order to escape. We do not find asteroid pairs with mass ratios larger than 0.2. Rotationally fissioned systems beyond this limit have insufficient energy to disrupt. We conclude that asteroid pairs are formed by the rotational fission of a parent asteroid into a proto-binary system, which subsequently disrupts under its own internal system dynamics soon after formation.

  9. Max Wolf's Discovery of Near-Earth Asteroid 887 Alinda

    NASA Astrophysics Data System (ADS)

    Connors, Martin; Mandel, Holger; Demleitner, Markus; Heidelberg Digitized Astronomical Plates Project

    2016-01-01

    Max Wolf, director of the Heidelberg Observatory (Landessternwarte Königsstuhl), was the most prodigious discoverer of asteroids in the early twentieth century. He is now best known for the discovery of the Trojan asteroids associated with Jupiter in 1906, but was a pioneer in the application of photographic techniques to astronomy, particularly for conducting asteroid surveys. His attention to detail and perseverance also led to the discovery of the near-Earth asteroid 887 Alinda, which is the eponym of an orbital class in 3:1 resonance with Jupiter. Alinda class contains several potentially hazardous asteroids, and has been particularly instructive in development of theories of eccentricity increase for resonant asteroids. Alinda was discovered on January 3, 1918, on the very edge of one of two plates taken with the 40 cm aperture Bruce double astrograph. The inability to reduce a long trail going off the plate meant that only one month later could the object again be found with the Bruce telescope, and later observed with the follow-up instrument, the 72 cm aperture Waltz reflector. In what Wolf referred to as "the greatest embarrassment of my life", reflector observations had him conclude that Alinda had a satellite. At a time when plates had to be exposed for several hours, laboriously developed and analyzed, and in the case of high eccentricity objects like Alinda, predicted with inadequate theories, Wolf's persistence allowed it never to be lost. Despite this, its essential resonant nature was not determined until 1969, despite the pioneering work by Brown (1911) on resonance in the asteroid belt and the knowledge dating to the late nineteenth century work of Kirkwood that commensurabilities were important in its structure. The majority of Wolf's plates are available as online scans through the Heidelberg Digitized Astronomical Plates project of the German Astrophysical Virtual Observatory, but the Alinda discovery plate, which was broken, was scanned

  10. Asteroid rotation rates

    NASA Technical Reports Server (NTRS)

    Dermott, S. F.; Harris, A. W.; Murray, C. D.

    1984-01-01

    A trend of increasing mean rotational frequency with increasing diameter is noted in asteroids with diameters greater than 120 km, irrespective of M-, S-, and C-type asteroid subset and family or nonfamily membership. This trend cannot be accounted for by observational selection. For asteroids with diameters smaller than 120 km mean rotational frequency increases with decreasing diameter, but within this group there is a subset with exceptionally long rotational periods. This marked change in the distribution at 120-km diameter could separate primordial asteroids from their collision products. It is also noted that, for asteroids of a given diameter, M asteroids rotate faster than S asteroids, which in turn rotate faster than C asteroids. For all types, family members rotate faster than nonfamily members.

  11. Name That Asteroid!

    NASA Video Gallery

    The OSIRIS-REx Asteroid Sample Return Mission is going to an asteroidto return a sample to Earth. Instead of traveling to asteroid 1999RQ36, the asteroid’s current name, we’re asking youth un...

  12. Physical Diversity of Near-Earth Asteroids from Arecibo Radar Observations

    NASA Astrophysics Data System (ADS)

    Taylor, Patrick A.; Howell, Ellen S.; Nolan, Michael C.; Richardson, James E.; Springmann, Alessondra

    2015-08-01

    Radar observations of near-Earth asteroids have revealed a heterogeneous population with diameters spanning meter to kilometer scales, diverse shapes ranging from simple spheroids to extremely irregular bodies, rotation periods stretching from minutes to weeks, and a spectrum of surface properties. Since 1998, the Arecibo Observatory S-band radar system has detected over 400 near-Earth asteroids. We find the radar-observed near-Earth asteroid population with absolute magnitude H < 21 is not dominated by a single category of basic shape: spheroids, multiple-asteroid systems, double-lobed contact binaries, elongated bodies, or irregularly shaped asteroids. A radar-observed binary fraction of 14% (N = 38; including two triple-asteroid systems) among near-Earth asteroids with H < 21 is in agreement with optical observations, while contact binaries account for a similar fraction (14%; N = 38). At smaller sizes, binaries and contact binaries are much rarer, with only three binaries and one contact binary with H < 21 detected thus far. The spin distribution of near-Earth asteroids estimated from radar matches very well with the spin distribution determined from optical lightcurves, including the well-known spin barrier for bodies with H < 21 and the curious lack of small, slowly rotating bodies with H > 21, despite different biases in these observing techniques. The shape and spin distributions of near-Earth asteroids observed with radar both show a distinct change in the population around H of 21 or 22 (100- to 200-m diameters), possibly indicating fundamental structural changes at this scale. Beyond constraining overall sizes and shapes, radar images as fine as 7.5-m resolution with Arecibo, akin to a low-cost flyby, reveal asteroid surfaces with ridges, concavities, crater-like depressions, angular facets, and boulders, details that constrain regolith properties and affect our understanding of geophysics in microgravity. Furthermore, the integrated surface properties

  13. AIDA: the Asteroid Impact & Deflection Assessment mission

    NASA Astrophysics Data System (ADS)

    Vincent, Jean-Baptiste

    2016-07-01

    The Asteroid Impact & Deflection Assessment (AIDA) mission is a joint cooperation between European and US space agencies that consists of two separate and independent spacecraft that will be launched to a binary asteroid system, the near-Earth asteroid Didymos, to assess the possibility of deflecting an asteroid trajectory by using a kinetic impactor. The European Asteroid Impact Mission (AIM) is under Phase A/B1 study at ESA from March 2015 until summer 2016. AIM is set to rendez-vous with the asteroid system a few months prior to the impact by the US Double Asteroid Redirection Test (DART) spacecraft to fully characterize the smaller of the two binary components. AIM is a unique mission as it will be the first time that a spacecraft will investigate the surface, subsurface, and internal properties of a small binary near Earth asteroid. In addition it will perform various important technology demonstrations that can serve other space missions: AIM will release a set of CubeSats in deep space and a lander on the surface of the smaller asteroid and for the first time, deep-space inter-satellite linking will be demonstrated between the main spacecraft, the CubeSats, and the lander, and data will also be transmitted from interplanetary space to Earth by a laser communication system. The knowledge obtained by this mission will have great implications for our understanding of the history of the Solar System. Small asteroids are believed to result from collisions and other processes (e.g., spinup, shaking) that made them what they are now. Having direct information on their surface and internal properties will allow us to understand how these processes work and transform these small bodies as well as, for this particular case, how a binary system forms. So far, our understanding of the collisional process and the validation of numerical simulations of the impact process rely on impact experiments at laboratory scales. With DART, thanks to the characterization of the

  14. The partial fission of fast spinning asteroids

    NASA Astrophysics Data System (ADS)

    Tardivel, Simon; Sanchez, Paul; Scheeres, Daniel J.

    2016-10-01

    The spin rates of asteroids systematically change over time due the Yarkovsky–O'Keefe–Radzievskii–Paddack (YORP) effect. Above a certain spin rate that depends on the body's density, regions of an asteroid can enter in tension, with components held to the body by cohesive forces. When the body fails, deformation or fission can occur. Catastrophic fission leading to complete disruption has been directly observed in active asteroid P/2013 R3. Partial fission, the loss of only part of the body, has been proposed as a mechanism for the formation of binaries and is explored here.The equatorial cavities of (341843) 2008 EV5 and of (185851) 2000 DP107 (a binary system) are consistent with a localized partial fission of the body (LPSC 2016 #1036). The examination of the gravity field of these bodies reveals that a mass placed within these cavities could be shed. In this mechanism, the outward pull of inertial forces creates an average stress at the cavity interface of ≈1 Pa for 2008 EV5 and ≈3 Pa for 2000 DP107 at spin periods of ≈3.15 h for the assumed densities of 1.3 g/cm3.This work continues the study of this partial, localized fission. Specifically, it addresses the issue of the low cohesion necessary to the mechanism. These cohesion values are typically lower than global strength values inferred on other asteroids (10 - 200 Pa), meaning that partial fission may occur prior to larger-scale deformations. Yet, several processes can explain the discrepancy, as they can naturally segregate particles by size. For instance, landslides or granular convection (Brazil nut effect) could bring larger boulders to the equator of the body, while finer particles are left at higher latitudes or sink to the center. Conversely, failure of the interior could bring boulders to the surface. The peculiar profile shape of these asteroids, shared by many binaries (e.g. 1999 KW4, 1996 FG3) may also be a clue of this heterogeneity, as this "spin top" shape is obtained in

  15. Constraining the Interior Geophysics of Rubble Pile Asteroids

    NASA Astrophysics Data System (ADS)

    Scheeres, D. J.; Jacobson, S.; McMahon, J.; Hirabayashi, M.

    2013-12-01

    The internal geophysics of small rubble pile asteroids are largely unknown, and standard geophysical theories are not well matched to the extreme environment these bodies exist in. Interior pressures within rapidly spinning rubble piles are predicted to be as small as a few Pascals, a regime in which small non-gravitational forces not considered for larger bodies may become important. Previous research has suggested that the standard geophysical models for internal energy dissipation in this regime require modification (Goldreich and Sari, ApJ 2009), adding additional uncertainty in the geophysics. We report on new theoretical and observational results that suggest a direct way in which fundamental geophysical parameters of small rubble pile asteroids can be constrained. Specifically, we will discuss how the ratio Q/k, tidal dissipation number over tidal Love number, can be inferred and more strictly constrained for primaries in small binary asteroid systems where the secondary is spin-synchronized and the primary is super-synchronous, the most common class of small asteroid binary systems. Jacobson & Scheeres (ApJ 2011) proposed that many of these binary asteroid systems may be in an equilibrium state where contractive Binary YORP forces balance against expansive tidal torques due to tidal distortion of the primary body. The predicted equilibrium semi-major axes for such binary asteroid systems (based on presumed values for the Binary YORP force and Q/k values) has been seen to be consistent with the observed sizes of many of these systems (see figure). Recently, it has also been reported that the spacecraft-accessible binary asteroid 1996 FG3 is in such an equilibrium state (Scheirich et al., Binaries Workshop 2013). The combined detection of such an equilibrium coupled with their theoretical model makes it feasible to sharply constrain the Q/k parameter for the primary asteroid in the 1996 FG3 system and extrapolate its functional form to other such systems. We

  16. Multiple asteroid rendezvous missions

    NASA Technical Reports Server (NTRS)

    Bender, D. F.; Friedlander, A. L.

    1979-01-01

    Asteroid missions, centered on multiple asteroid rendezvous missions to main belt asteroids, are discussed and the required solar electric propulsion for these missions as well as the current performance estimates are examined. A brief statistical analysis involving asteroid availability transfer requirements and propulsion system capabilities is given, leading to a prediction that 5 to 8 asteroids can be encountered with a single launch. Measurement techniques include visual imaging, radio tracking, magnetometry, and in the case of landers, seismometry. The spacecraft will be propelled by a solar electric system with a power level of 25 kW to 40 kW and tour possibilities for 13 different asteroids have been developed. Preliminary estimates of asteroid triaxiality are made to calculate the effect of close orbits.

  17. Asteroid Lightcurve Analysis at CS3-Palmer Divide Station: 2015 June-September

    NASA Astrophysics Data System (ADS)

    Warner, Brian D.

    2016-01-01

    Lightcurves for 29 main-belt asteroids were obtained at the Center for Solar System Studies-Palmer Divide Station (CS3-PDS) from 2015 June-September. Hungaria members 1876 Napolitania and (47141) 1999 HB3 are suspected binary asteroids.

  18. Kinetic-Impact Asteroid Defense: Dependence on Porosity and Composition

    NASA Astrophysics Data System (ADS)

    Gisler, G. R.; Ferguson, J. M.; Plesko, C. S.; Weaver, R.

    2015-12-01

    In this work we study the deflection of hazardous near-earth asteroids using a kinetic impactor. The momentum delivered to the asteroid can be greater than the momentum of the impactor because of the reaction force produced by ablation from the impact crater. We use an adaptive-mesh hydrocode to study the momentum-enhancement factor, or beta, varying the assumptions regarding the equation of state, strength, and porosity of the target. Spall from the back side of the asteroid, which partly counters the favorable effect of ablation, is also included in the calculations. The efficiency is shown to be most strongly dependent on the asteroid's porosity, which unfortunately is the most difficult quantity to obtain via remote observations. This study is applied both to the proposed deflection of the 150-meter diameter moon of the binary asteroid 65803 Didymos by the AIDA/DART mission, and to the potential deflection of the 492-meter diameter asteroid 101955 Bennu, which has some possible Earth impacts late in the 22nd century, and is the target of the planned OSIRIS-Rex mission. Figures of merit from both these studies include the bulk momentum imparted to the asteroid and the degree to which the asteroid is disrupted. (LA-UR-15-26214)

  19. Asteroid exploration and utilization

    NASA Technical Reports Server (NTRS)

    Radovich, Brian M.; Carlson, Alan E.; Date, Medha D.; Duarte, Manny G.; Erian, Neil F.; Gafka, George K.; Kappler, Peter H.; Patano, Scott J.; Perez, Martin; Ponce, Edgar

    1992-01-01

    The Earth is nearing depletion of its natural resources at a time when human beings are rapidly expanding the frontiers of space. The resources possessed by asteroids have enormous potential for aiding and enhancing human space exploration as well as life on Earth. Project STONER (Systematic Transfer of Near Earth Resources) is based on mining an asteroid and transporting raw materials back to Earth. The asteroid explorer/sample return mission is designed in the context of both scenarios and is the first phase of a long range plan for humans to utilize asteroid resources. Project STONER is divided into two parts: asteroid selection and explorer spacecraft design. The spacecraft design team is responsible for the selection and integration of the subsystems: GNC, communications, automation, propulsion, power, structures, thermal systems, scientific instruments, and mechanisms used on the surface to retrieve and store asteroid regolith. The sample return mission scenario consists of eight primary phases that are critical to the mission.

  20. The asteroid ring

    NASA Technical Reports Server (NTRS)

    Dermott, S. F.; Murray, C. D.

    1982-01-01

    From a statistical analysis of asteroid orbital period data, it is shown that the present distribution of asteroids is strongly correlated with the present orbital period of Jupiter (to 1 part in 5000). By analyzing the distribution of orbital eccentricities and inclinations it is shown that the resonant structure of the belt was formed after the asteroids dispersed from the near-coplanar disk in which they accreted.

  1. Witnessing Extrasolar Asteroid Destruction?

    NASA Astrophysics Data System (ADS)

    Xu, Siyi; Jura, Michael; Su, Kate; Meng, Huan

    2014-11-01

    40 white dwarfs with excess infrared radiation due to a circumstellar dust disk from tidally disrupted asteroids have been identified. Recently, we identified one dusty white dwarf whose infrared fluxes have been increasing since May 2014. Very likely, it is caused by a recent tidal disruption event of extrasolar asteroid. We propose DDT to follow it up in a timely manner because the flare could dissipate very soon. This proposal provides a unique opportunity to study the destruction of an extrasolar asteroid.

  2. Science case for the Asteroid Impact Mission (AIM): A component of the Asteroid Impact & Deflection Assessment (AIDA) mission

    NASA Astrophysics Data System (ADS)

    Michel, Patrick; Cheng, A.; Küppers, M.; Pravec, P.; Blum, J.; Delbo, M.; Green, S. F.; Rosenblatt, P.; Tsiganis, K.; Vincent, J. B.; Biele, J.; Ciarletti, V.; Hérique, A.; Ulamec, S.; Carnelli, I.; Galvez, A.; Benner, L.; Naidu, S. P.; Barnouin, O. S.; Richardson, D. C.; Rivkin, A.; Scheirich, P.; Moskovitz, N.; Thirouin, A.; Schwartz, S. R.; Campo Bagatin, A.; Yu, Y.

    2016-06-01

    The Asteroid Impact & Deflection Assessment (AIDA) mission is a joint cooperation between European and US space agencies that consists of two separate and independent spacecraft that will be launched to a binary asteroid system, the near-Earth asteroid Didymos, to test the kinetic impactor technique to deflect an asteroid. The European Asteroid Impact Mission (AIM) is set to rendezvous with the asteroid system to fully characterize the smaller of the two binary components a few months prior to the impact by the US Double Asteroid Redirection Test (DART) spacecraft. AIM is a unique mission as it will be the first time that a spacecraft will investigate the surface, subsurface, and internal properties of a small binary near-Earth asteroid. In addition it will perform various important technology demonstrations that can serve other space missions. The knowledge obtained by this mission will have great implications for our understanding of the history of the Solar System. Having direct information on the surface and internal properties of small asteroids will allow us to understand how the various processes they undergo work and transform these small bodies as well as, for this particular case, how a binary system forms. Making these measurements from up close and comparing them with ground-based data from telescopes will also allow us to calibrate remote observations and improve our data interpretation of other systems. With DART, thanks to the characterization of the target by AIM, the mission will be the first fully documented impact experiment at asteroid scale, which will include the characterization of the target's properties and the outcome of the impact. AIDA will thus offer a great opportunity to test and refine our understanding and models at the actual scale of an asteroid, and to check whether the current extrapolations of material strength from laboratory-scale targets to the scale of AIDA's target are valid. Moreover, it will offer a first check of the

  3. The GTC mid-infrared spectroscopic program of primitive outer-belt asteroids

    NASA Astrophysics Data System (ADS)

    Licandro, J.; Alvarez-Iglesias, C. Carlos; Cabrera-Lavers, A.; Ali-Lagoa, V.; Pinilla-Alonso, N.; Campins, H.; de Leon, J.; Kelley, M.

    2014-07-01

    Asteroids in the outer edge of the asteroid belt (Cybeles, Hildas, and Jupiter Trojans) may provide a number of clues to the origin and evolution of the asteroid belt and the formation of our planetary system. They have a pristine composition, experienced little heating and may contain a significant fraction of ice in their interiors. The origin of these populations is still under debate. Levison et al. (2009) suggested that a large fraction of these bodies are transneptunian objects (TNOs) moved to these resonances in an early epoch of the Solar System called the ''Late Heavy Bombardment'' (LHB). To compare the physical properties of these asteroid populations with TNOs and comets is thus a strong test of dynamical models. In mid 2013, we started a mid-infrared photometric and spectroscopic program in the N-band using the CANARICAM camera-spectrograph at the 10.4-m GTC telescope at the ''Roque de los Muchachos'' Obserbatory (Canary Islands, Spain). We aim to study the surface composition and key properties such as radius, albedo, and thermal inertia based on their low-resolution 8--13-micron spectra and N-band photometry. We already obtained the spectra of 5 objects, that of (225) Henrieta is shown as an example in the Figure. The three published spectra of Trojan asteroids (Emery et al. 2006) and of (65) Cybele (Licandro et al. 2011) exhibit clear emissivity features from which the compositional and physical properties can be inferred. The spectra of these objects strongly resemble one another, presenting an emission plateau due to silicates at about 9.1-11.5 microns (the Si-O stretch fundamental). Fine-grained silicates in a very porous (fairly castle) structure, and no other mineral group (Emery et al. 2006, Vernazza et al. 2012), reproduce the major features of the Trojans and Cybele asteroid spectra. In this work, we present the preliminary results of our observational program including the N-band spectra, size, and albedo of the already observed 5 asteroids

  4. The Trojan Horse Method in nuclear astrophysics

    SciTech Connect

    Spitaleri, C.; Mukhamedzhanov, A. M.; Blokhintsev, L. D.; Cognata, M. La; Pizzone, R. G.; Tumino, A.

    2011-12-15

    The study of energy production and nucleosynthesis in stars requires an increasingly precise knowledge of the nuclear reaction rates at the energies of interest. To overcome the experimental difficulties arising from the small cross sections at those energies and from the presence of the electron screening, the Trojan Horse Method has been introduced. The method provides a valid alternative path to measure unscreened low-energy cross sections of reactions between charged particles, and to retrieve information on the electron screening potential when ultra-low energy direct measurements are available.

  5. Asteroid spectroscopy with Gaia

    NASA Astrophysics Data System (ADS)

    Delbo', Marco; Gayon-Markt, Julie; Busso, Giorgia; Brown, Antony; Galluccio, Laurent; Ordenovic, Christophe; Bendjoya, Philippe; Tanga, Paolo

    2012-12-01

    The Gaia space mission of the European Space Agency (ESA) will survey the entire sky with a limiting magnitude of about 20 in the V-band. Gaia is expected to be launched in the summer of 2013. Gaia will also observe about 400,000 asteroids, for which high precision astrometry and photometry will be obtained. Here we discuss Gaia spectrophotometric observations of asteroids, the methods for the treatment of the data, the expected performances of the spectrophotometers and the spectral classification of asteroids. We estimate that a robust spectral classification can be obtained for at least 100,000 asteroids from the low-resolution spectra obtained by Gaia.

  6. Neptune trojan formation during planetary instability and migration

    NASA Astrophysics Data System (ADS)

    Gomes, R.; Nesvorný, D.

    2016-08-01

    Aims: We investigate the process of Neptune trojan capture and permanence in resonance up to the present time based on a planetary instability migration model. Methods: We do a numerical simulation of the migration of the giant planets in a planetesimal disk. Several planetesimals became trapped in coorbital resonance with Neptune, but no trojan survived to the end of the integration at 4.5 Gy. We increased the statistics by running synthetic integrations with cloned particles from the original integration and keeping the same migration rates of the planets. Results: For the synthetic integrations, Neptune trojans survived to the end of the simulations. The total mass that corresponds to these surviving trojans is about 1.6 × 10-4 Earth mass and the distributions of eccentricities, inclinations, and libration amplitudes are respectively 0.007-0.173, 4.9°-32.9°, and 6.9°-64.3°. In a specific run where Neptune to Uranus mean motion ratio reached 1.963 and decreased to its present value (1.961), many more trojans escaped the coorbital resonance with Neptune and in the end there was an equivalent mass of 5 × 10-5 Earth mass of Neptune trojans. Conclusions: The simulations yielded Neptune trojans that match the orbital distribution of real Neptune trojans quite well. Since planetary migration in an instability model shows the possibility that in the past Neptune was a little farther from the Sun than it is today, it is reasonable to consider this possibility to explain the relatively low mass of Neptune trojans.

  7. Asteroid selection for mission opportunities

    NASA Technical Reports Server (NTRS)

    Chapman, C. R.; Stone, C. A.

    1972-01-01

    A study to assess the present state of knowledge of asteroids as well as the rate of change of that knowledge to better identify the mission and target priorities for advanced planning of asteroidal flights in the 1980's is presented. Topics discussed include; the present state of asteroid knowledge, the scientific goals and priorities attached to asteroid exploration, the anticipated advances in knowledge over the current decade, asteroid mission consideration, and asteroid selection. Data sheets for 118 asteroids are contained. These are asteroids for which some data is available over and above orbital parameters and magnitude.

  8. Detection of a trailing (L5) Neptune Trojan.

    PubMed

    Sheppard, Scott S; Trujillo, Chadwick A

    2010-09-10

    The orbits of small Solar System bodies record the history of our Solar System. Here, we report the detection of 2008 LC18, which is a Neptune Trojan in the trailing (L5) Lagrangian region of gravitational equilibrium within Neptune's orbit. We estimate that the leading and trailing Neptune Trojan regions have similarly sized populations and dynamics, with both regions dominated by high-inclination objects. Similar populations and dynamics at both Neptune Lagrangian regions indicate that the Trojans were likely captured by a migrating, eccentric Neptune in a dynamically excited planetesimal population.

  9. Asteroids and Amateur Astronomers.

    ERIC Educational Resources Information Center

    Gunter, Jay U.

    1985-01-01

    Traces asteroid discoveries by amateurs from the 19th century to the present. The importance and necessity of amateur work are noted, especially with reference to observing and documenting occultations (one object passes directly in front of another which is farther away). Suggestions are made for viewing asteroids as a hobby. (DH)

  10. The Double Asteroid Redirection Test in the AIDA Project

    NASA Astrophysics Data System (ADS)

    Cheng, Andrew; Rivkin, Andrew; Michel, Patrick

    2016-04-01

    The Asteroid Impact & Deflection Assessment (AIDA) mission will be the first space experiment to demonstrate asteroid impact hazard mitigation by using a kinetic impactor. AIDA is a joint ESA-NASA cooperative project, that includes the ESA Asteroid Impact Mission (AIM) rendezvous mission and the NASA Double Asteroid Redirection Test (DART) mission. The AIDA target is the near-Earth binary asteroid 65803 Didymos, which will make an unusually close approach to Earth in October, 2022. The ~300-kg DART spacecraft is designed to impact the Didymos secondary at 7 km/s and demonstrate the ability to modify its trajectory through momentum transfer. DART and AIM are currently Phase A studies supported by NASA and ESA respectively. The primary goals of AIDA are (1) perform a full-scale demonstration of the spacecraft kinetic impact technique for deflection of an asteroid, by targeting an object larger than ~100 m and large enough to qualify as a Potentially Hazardous Asteroid; (2) measure the resulting asteroid deflection, by targeting the secondary member of a binary NEO and measuring the period change of the binary orbit; (3) understand the hyper-velocity collision effects on an asteroid, including the long-term dynamics of impact ejecta; and validate models for momentum transfer in asteroid impacts, based on measured physical properties of the asteroid surface and sub-surface. The primary DART objectives are to demonstrate a hyper-velocity impact on the Didymos moon and to determine the resulting deflection from ground-based observatories. The DART impact on the Didymos secondary will cause a measurable change in the orbital period of the binary. Supporting Earth-based optical and radar observations and numerical simulation studies are an integral part of the DART mission. The baseline DART mission launches in December, 2020 to impact the Didymos secondary in September, 2022. There are multiple launch opportunities for DART leading to impact around the 2022 Didymos close

  11. Volatiles in asteroids

    NASA Astrophysics Data System (ADS)

    Campins, H.

    2014-07-01

    For more than three decades, hydrated minerals have been identified in asteroids. The distribution of these minerals among asteroid spectral types and heliocentric distance has been somewhat unexpected, and there is also diversity in the composition of these hydrated minerals (e.g., Takir and Emery 2012). In addition, water ice and organic molecules have been detected on two asteroids (Campins et al. 2010; Rivkin and Emery 2010; Licandro et al. 2011) and water vapor is emanating from (1) Ceres (Küppers et al. 2014). These discoveries have important implications on current views of primitive asteroids, the nature of active asteroids or main-belt comets, the dynamics of the early Solar System, and the delivery of water and organic molecules to the Earth. They are also relevant to several space missions, including Dawn, Gaia, Hayabusa2, OSIRIS-REx ,and WISE.

  12. 12. TROJAN MILL, INTERIOR SHOWING PRIMARY MILL No. 1 (MONADNOCK ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. TROJAN MILL, INTERIOR SHOWING PRIMARY MILL No. 1 (MONADNOCK CHILEAN) FROM EAST, c. 1912. ELEVATOR No. 1 ADJACENT TO MILL. CREDIT WR. - Bald Mountain Gold Mill, Nevada Gulch at head of False Bottom Creek, Lead, Lawrence County, SD

  13. 9. TROJAN MILL, EXTERIOR FROM NORTHWEST, c. 191828. WINTER SNOW ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. TROJAN MILL, EXTERIOR FROM NORTHWEST, c. 1918-28. WINTER SNOW SHOWS LINE OF CRUDE ORE BIN STAIR. CREDIT JW. - Bald Mountain Gold Mill, Nevada Gulch at head of False Bottom Creek, Lead, Lawrence County, SD

  14. 313 new asteroid rotation periods from Palomar Transient Factory observations

    SciTech Connect

    Chang, Chan-Kao; Ip, Wing-Huen; Lin, Hsing-Wen; Cheng, Yu-Chi; Ngeow, Chow-Choong; Yang, Ting-Chang; Waszczak, Adam; Kulkarni, Shrinivas R.; Levitan, David; Sesar, Branimir; Prince, Thomas A.; Laher, Russ; Surace, Jason

    2014-06-10

    A new asteroid rotation period survey has been carried out by using the Palomar Transient Factory (PTF). Twelve consecutive PTF fields, which covered an area of 87 deg{sup 2} in the ecliptic plane, were observed in the R band with a cadence of ∼20 minutes during 2013 February 15-18. We detected 2500 known asteroids with a diameter range of 0.5 km ≤D ≤ 200 km. Of these, 313 objects had highly reliable rotation periods and exhibited the 'spin barrier' at ∼2 hr. In contrast to the flat spin-rate distribution of the asteroids with 3 km ≤D ≤ 15 km shown by Pravec et al., our results deviated somewhat from a Maxwellian distribution and showed a decrease at the spin rate greater than 5 rev day{sup –1}. One superfast rotator candidate and two possible binary asteroids were also found in this work.

  15. Sizes, Shapes, and Satellites of Asteroids from Occultations

    NASA Astrophysics Data System (ADS)

    Dunham, David W.; Herald, David; Preston, Steve; Timerson, Brad; Maley, Paul; Frappa, Eric; Hayamizu, Tsutomu; Talbot, John; Poro, Atila

    2016-01-01

    For 40 years, the sizes and shapes of many dozens of asteroids have been determined from observations of asteroidal occultations, and over a thousand high-precision positions of the asteroids relative to stars have been measured. Some of the first evidence for satellites of asteroids was obtained from the early efforts; now, the orbits and sizes of some satellites discovered by other means have been refined from occultation observations. Also, several close binary stars have been discovered, and the angular diameters of some stars have been measured from analysis of these observations. The International Occultation Timing Association (IOTA) coordinates this activity worldwide, from predicting and publicizing the events, to accurately timing the occultations from as many stations as possible, and publishing and archiving the observations.

  16. Orbits of real and fictitious asteroids studied by numerical integration

    NASA Astrophysics Data System (ADS)

    Schubart, J.

    1994-05-01

    The paper starts with a review of the author's various numerical studies on asteroid orbits, ruled by the violent evolution of the computer technique, and continues with a collection of starting values of orbital elements. This collection supplements the author's numerous papers on orbits at resonances of mean motion with respect to Jupiter. Especially, it refers to work on Trojan-type motion, mainly done together with R. Bien, and to the Hilda and Hecuba cases of resonance. It will allow the extension of intervals covered by numerical integration in interesting cases. The collection contains hitherto unpublished examples of orbits and additional comments. In particular, special remarks and some new results refer to low-eccentricity motion of Hecuba type.

  17. The Double Asteroid Redirection Test in the AIDA Mission

    NASA Astrophysics Data System (ADS)

    Cheng, Andrew; Reed, Cheryl; Rivkin, Andrew

    2016-07-01

    The Asteroid Impact & Deflection Assessment (AIDA) mission will be the first space experiment to demonstrate asteroid impact hazard mitigation by using a kinetic impactor. AIDA is a joint ESA-NASA cooperative project, consisting of the ESA Asteroid Impact Mission (AIM) rendezvous mission and the NASA Double Asteroid Redirection Test (DART) mission. The AIDA target is the near-Earth binary asteroid 65803 Didymos, which will make an unusually close approach to Earth in October, 2022. The DART spacecraft is designed to impact the Didymos secondary at 7 km/s and demonstrate the ability to modify its trajectory through momentum transfer. DART and AIM are currently Phase A studies supported by NASA and ESA respectively. The primary goals of AIDA are (1) perform a full-scale demonstration of the spacecraft kinetic impact technique for deflection of an asteroid; (2) measure the resulting asteroid deflection, by targeting the secondary member of a binary NEO and measuring the resulting changes of the binary orbit; and (3) study hyper-velocity collision effects on an asteroid, validating models for momentum transfer in asteroid impacts based on measured physical properties of the asteroid surface and sub-surface, and including long-term dynamics of impact ejecta. The primary DART objectives are to demonstrate a hyper-velocity impact on the Didymos moon and to determine the resulting deflection from ground-based observations. The DART impact on the Didymos secondary will change the orbital period of the binary which can be measured by supporting Earth-based optical and radar observations. The baseline DART mission launches in December, 2020 to impact the Didymos secondary in September,2022. There are multiple launch opportunities for DART leading to impact around the 2022 Didymos close approach to Earth. The AIM spacecraft will be launched in Dec. 2020 and arrive at Didymos in spring, 2022, several months before the DART impact. AIM will characterize the Didymos binary system

  18. Galileo asteroid encounter navigation

    NASA Technical Reports Server (NTRS)

    Murrow, D. W.; Chodas, P. W.; Kallemeyn, P. H.

    1990-01-01

    The Galileo spacecraft will be targeted to encounter one or more asteroids during its cruise to Jupiter. Accurate navigation will maximize science return from these asteroid flyby opportunities. Navigation errors for these encounters are dominated by uncertainties in the asteroid ephemeris, which is obtained from fits to ground-based observations. As the spacecraft approaches, on-board optical navigation dramatically improves knowledge of the spacecraft-relative asteroid position normal to the line of sight, while correlations in the asteroid ephemeris provide moderate improvement along the approach direction. The remaining uncertainty in encounter time can be further reduced only by improving the ground-based asteroid ephemeris. Uncertainties perpendicular to the line of sight can be reduced by improving the timing of optical navigation images and their placement with respect to the star background. At the closest approach to the asteroid Gaspra, the one-sigma errors in knowledge of the spacecraft position are less than 10 km in position and 25 seconds in encounter time.

  19. Pan-STARRS 1 discoveries of new Neptune Trojans: Preliminary results

    NASA Astrophysics Data System (ADS)

    Lin, Hsing-Wen; Chen, Yin Tung; Holman, Matthew J.; Ip, Wing-Huen

    2015-11-01

    Neptune Trojans are a well-known probe of the dynamical environment of the outer solar system. However, given the small number of known Neptune Trojans, many questions remain: the total number, the size distribution, and the orbital distribution of Neptune Trojans are all still unclear.Pan-STARRS 1 (PS1) survey provides a chance to comprehensively investigate the properties of Neptune Trojan population. In this study we present our preliminary results of a PS1 search for new Neptune Trojans. We report several candidates. At least one unstable L5 trojan has been confirmed. The preliminary orbital distribution of Neptune Trojan populations shows a possible L4/L5 distribution asymmetry from the combination of our new candidates and the known Neptune Trojans.

  20. Nuclear Astrophysics with the Trojan Horse Method

    NASA Astrophysics Data System (ADS)

    Spitaleri, Claudio

    2015-04-01

    In stars nuclear reactions take place at physical conditions that make very hard their measurements in terrestrial laboratories. Indeed in astrophysical environments nuclear reactions between charged nuclei occur at energies much lower than the Coulomb barrier and the corresponding cross section values lie in the nano or picobarn regime, that makes their experimental determination extremely difficult. This is due to the very small barrier Coulomb penetration factor, which produces an exponential fall off of the cross section as a function of energy. Additionally, the presence of the electron screening needs to be properly taken into account when dealing with cross section measurements at low-energies. The Trojan Horse Method (THM) represents an independent experimental technique, allowing one to measure astrophysical S(E)-factor bared from both Coulomb penetration and electron screening effects. The main advantages and the most recent results are here shown and discussed.

  1. Asteroid clusters similar to asteroid pairs

    NASA Astrophysics Data System (ADS)

    Pravec, Petr; Vokrouhlicky, David; Fatka, Petr; Kusnirák, Peter; Hornoch, Kamil; Galád, Adrián

    2016-10-01

    We study five small, tight and young clusters of asteroids. They are placed around following largest (primary) bodies: (11842) Kap'bos, (14627) Emilkowalski, (16598) 1992 YC2, (21509) Lucascavin and (39991) 1998 HR37. Each cluster has 2-4 secondaries that are tightly clustered around the primary body, with distance in the 5-dimensional space of mean orbital elements mostly within 10 m/s, and always < 23 m/s. Backward orbital integrations indicate that they formed between 105 and 106 yr ago. In the P1-q space, where P1 is the primary's spin period and q = Σ Mj/M1 is the total secondary-to-primary mass ratio, the clusters lie in the same range as asteroid pairs formed by rotational fission. We have extended the model of a proto-system separation after rotational fission by Pravec et al. (2010) for application to systems with more than one secondary and found a perfect match for the five tight clusters. We find these clusters to be similar to asteroid pairs and we suggest that they are "extended pairs", having 2-4 escaped secondaries rather than just one secondary as in the case of an asteroid pair. We compare them to six young mini-families (1270) Datura, (2384) Schulhof, (3152) Jones, (6825) Irvine, (10321) Rampo and (20674) 1999 VT1. These mini-families have similar ages, but they have a higher number of members and/or they show a significantly larger spread in the mean orbital elements (dmean on an order of tens m/s) than the five tight clusters. In the P1-q space, all but one of the mini-families lie in the same range as asteroid pairs and the tight clusters; the exception is the mini-family of (3152) Jones which appears to be a collisional family. A possibility that the other five mini-families were also formed by rotational fission as we suggest for the tight clusters ("extended asteroid pairs") is being explored.Reference:Pravec, P., et al. Formation of asteroid pairs by rotational fission. Nature 466, 1085-1088.

  2. Applied Astronomy: Asteroid Prospecting

    NASA Astrophysics Data System (ADS)

    Elvis, M.

    2013-09-01

    In the age of asteroid mining the ability to find promising ore-bearing bodies will be valuable. This will give rise to a new discipline- "Applied Astronomy". Just as most geologists work in industry, not in academia, the same will be true of astronomers. Just how rare or common ore-rich asteroids are likely to be, and the skills needed to assay their value, are discussed here, with an emphasis on remote - telescopic - methods. Also considered are the resources needed to conduct extensive surveys of asteroids for prospecting purposes, and the cost and timescale involved. The longer-term need for applied astronomers is also covered.

  3. Hilda Asteroid Colors: Insight into Giant Planet Migration?

    NASA Astrophysics Data System (ADS)

    Sharkey, Benjamin; Ryan, Erin L.; Woodward, Charles E.; Noll, Keith S.

    2016-01-01

    The Hilda asteroids are a unique population of small bodies that are locked in a 3:2 mean motion resonance with Jupiter. Unlike other resonances in the asteroid belt, the 3:2 is a stable resonance at 3.95 AU. Objects at this resonance have stable orbits for at least 2 GYr and, more likely, for the age of the Solar System. In an instantaneous top down view of the solar system, the Hildas approximately trace a triangle with over-densities of asteroids near the L3, L4 and L5 Jovian Lagrange points. This configuration is cited as evidence that Jupiter migrated inwards by ~0.4 AU. Stable Hilda orbits have mean eccentricities of 0.16 with typical perihelia of 3.15 AU. These latter properties, in terms of observability and accessibility to spacecraft, are a major advantage that distinguishes the Hildas from other populations of potential scientific interest such as the Jovian Trojans. The Outer Main Belt (OMB) also has many objects that may have originated in the outer protoplanetary disk (OPD). However, the OMB appears to be more mixed with objects from elsewhere in the Main Belt and enjoys only a small advantage in terms of brightness for a given diameter and albedo. The intrinsic collisional probability for objects in the Hilda population is also a factor of 3 to 5 less than the collisional probabilities for Trojan and OMB populations. Thus, the Hildas likely represent a significant population of objects unaltered due to collisional processing. Here we discuss findings of our ongoing NASA Planetary Astronomy program to obtain Sloan optical (g' r' i' z') colors of Hilda-group asteroids. The loci of these colors are compared to the Kuiper Belt populations to test post-formation migration effects of the giant planets in our solar system on the small body population. In part, this work was conducted as part of a University of Minnesota Undergraduate Research Scholarship, and is supported by NASA PAST Award NNX13AJ11G.

  4. An Experimental Path to Constraining the Origins of the Jupiter Trojans Using Observations, Theoretical Predictions, and Laboratory Simulants

    NASA Astrophysics Data System (ADS)

    Blacksberg, Jordana; Eiler, John; Brown, Mike; Ehlmann, Bethany; Hand, Kevin; Hodyss, Robert; Mahjoub, Ahmed; Poston, Michael; Liu, Yang; Choukroun, Mathieu; Carey, Elizabeth; Wong, Ian

    2014-11-01

    Hypotheses based on recent dynamical models (e.g. the Nice Model) shape our current understanding of solar system evolution, suggesting radical rearrangement in the first hundreds of millions of years of its history, changing the orbital distances of Jupiter, Saturn, and a large number of small bodies. The goal of this work is to build a methodology to concretely tie individual solar system bodies to dynamical models using observables, providing evidence for their origins and evolutionary pathways. Ultimately, one could imagine identifying a set of chemical or mineralogical signatures that could quantitatively and predictably measure the radial distance at which icy and rocky bodies first accreted. The target of the work presented here is the Jupiter Trojan asteroids, predicted by the Nice Model to have initially formed in the Kuiper belt and later been scattered inward to co-orbit with Jupiter. Here we present our strategy which is fourfold: (1) Generate predictions about the mineralogical, chemical, and isotopic compositions of materials accreted in the early solar system as a function of distance from the Sun. (2) Use temperature and irradiation to simulate evolutionary processing of ices and silicates, and measure the alteration in spectral properties from the UV to mid-IR. (3) Characterize simulants to search for potential fingerprints of origin and processing pathways, and (4) Use telescopic observations to increase our knowledge of the Trojan asteroids, collecting data on populations and using spectroscopy to constrain their compositions. In addition to the overall strategy, we will present preliminary results on compositional modeling, observations, and the synthesis, processing, and characterization of laboratory simulants including ices and silicates. This work has been supported by the Keck Institute for Space Studies (KISS). The research described here was carried out at the Jet Propulsion Laboratory, Caltech, under a contract with the National

  5. Dawn: mission to asteroids

    NASA Video Gallery

    NASA’s Dawn spacecraft is the first to orbit an object in the main asteroid belt. Join NASA scientist and program manager Tony Carro and find out what NASA is hoping to learn from these big rocks.

  6. Tiny Asteroid Approaches Earth

    NASA Video Gallery

    On Oct. 15, 2010, NASA astronomer Rob Suggs captured this view of the tiny asteroid 2010 TG19 as it made its way among the stars of the constellation Pegasus. It will continue to approach during th...

  7. On the growth and stability of Trojan planets

    NASA Astrophysics Data System (ADS)

    Cresswell, P.; Nelson, R. P.

    2009-01-01

    Aims: We investigate the stability of those low-mass Trojan planets that form in a protoplanetary disc and subsequently accrete gas to become gas giants. Methods: We calculate their evolution before, during, and after gas disc dispersal. A two-dimensional hydrodynamics code combined with an N-body solver is used to evolve the system of disc and planets. Gas disc dispersal is simulated in a simple manner by assuming global exponential decay of the disc mass, leading to the stalling of migration after semi-major axes have approximately halved from their initial values. We consider Trojan pairs with different initial masses and gas accretion rates and gas disc models with different masses and viscosities. An N-body code, adapted to model disc forces, is used to examine large-scale migration and the formation of very short period Trojan planets. Results: For each combination of planetary pair and disc model that we consider in our hydrodynamic simulations, each Trojan system remains stable before, during, and after disc dispersal. The long-term stability of these systems in the absence of gas is tested using N-body simulations, and all systems remain stable for those evolution times equal to 109 years. Eccentricities remain low (e < 0.02) in all cases. Increases in the amplitude of libration about the L_4/L5 Lagrange points accompany the inward migration, and during very large-scale migration Trojan systems may be disrupted prior to the onset of disc dispersal. Conclusions: The stability of Trojan pairs during rapid type I migration, during the transition to type II migration with the accompanying gap formation in the gas disc, and during gas loss when the disc disperses, indicates that isolated Trojan planet systems are very stable. If a common mechanism exists for their formation, we suggest they may be readily observed in nature.

  8. Regolith Levitation on Small Fast Rotating Asteroids

    NASA Astrophysics Data System (ADS)

    Campo Bagatin, Adriano; Moreno, Fernando; Molina, Antonio

    2014-11-01

    A number of NEAs larger than few hundred meters are found with relatively high spin rates (from ~2.2 to less than 4 hr, depending on composition). On those bodies, local acceleration near their equator may be directed outwards, as in the case of the primaries of binary asteroids Didymos and 1996 FG3. They both are potential targets of future space missions. What are the effects of high spin states on regolith material at low asteroidal latitudes?NEAs come from the asteroid belt and are believed to be mostly gravitational aggregates at D > 0.5 - 1 km due to their former collisional evolution history (Campo Bagatin et al, 2001). Once in the inner Solar System, NEAs may undergo spin up evolution through YORP causing their components to disperse, shed mass or fission and eventually form binary, multiple systems or asteroid pairs (Walsh et al, 2008, Jacobson and Scheers, 2010, Pravec et al, 2009 and 2010). The end state of those events is often an object spinning above any Chandrasekhar stability limit, kept together by friction (Holsapple, 2007) and sometimes characterized by an equatorial “bulge”, as shown by radar images (Ostro et al, 2006).The centrifugal force acting on surface particles at equatorial latitudes may overcome the gravitational pull of the asteroid itself, and particles may leave its suface. Centrifugal is an apparent contact force, and as soon as particles lift off they mainly move under the gravitational field of the asteroid and the satellite, they may levitate for some time, land on the surface and repeat this cycle over and over. We are studying the motion of particles in the 1 μm to 10 cm range in the non-inertial reference frame of the rotating primary, accounting for centrifugal and Coriolis apparent forces as well as the gravitational fields of the primary, the secondary, the Sun and the radiation forces by the Sun itself. The main features of this effect are presented in the case of Didymos and 1996 FG3.

  9. Asteroid Evolution: Role of geotechnical properties

    NASA Astrophysics Data System (ADS)

    Sanchez Lana, Diego P.

    2015-08-01

    Over the last decade of Planetary research, the scientific community has made many advances in their understanding of the evolution of asteroids in the Solar System. One particular area of fruitful study started with the bold idea that these small planetary bodies could be gravitational aggregates and initially motivated by several different observations and early simulations.If we start with the idea that asteroids are aggregates of different sized components, and not singular monolithic bodies, it is possible to study them with some of the tools that have been used in the fields of Soil Mechanics and Granular Dynamics. In them, parameters such as porosity, cohesive and tensile strength, angles of friction and repose, particle size distributions, stress states, heterogeneity and yield criteria among others, determine how these granular systems will react when subjected to different, changing, external factors. These external factors are believed to have produced and shaped the asteroids that now exist around us and include solar photon momentum, gravitational tides, micro- and macro-impacts and internal energy dissipation.In this presentation we will review what is known about the surface and interiors of rubble pile asteroids, how different theoretical, experimental and simulation tools have been used to study them, how space mission and ground-based observations have shaped our understanding of their physical reality, and what we expect to learn from future missions. The talk will also touch on some of the latest findings obtained by different groups. In particular we will discuss the rotational evolution of self-gravitating aggregates under the influence of the YORP effect and how their angles of friction, tensile strength, porosity, internal structure and density give rise to different disruption modes and the role they play in the formation of asteroids pairs, tumblers and binary systems.

  10. Asteroids@Home

    NASA Astrophysics Data System (ADS)

    Durech, Josef; Hanus, J.; Vanco, R.

    2012-10-01

    We present a new project called Asteroids@home (http://asteroidsathome.net/boinc). It is a volunteer-computing project that uses an open-source BOINC (Berkeley Open Infrastructure for Network Computing) software to distribute tasks to volunteers, who provide their computing resources. The project was created at the Astronomical Institute, Charles University in Prague, in cooperation with the Czech National Team. The scientific aim of the project is to solve a time-consuming inverse problem of shape reconstruction of asteroids from sparse-in-time photometry. The time-demanding nature of the problem comes from the fact that with sparse-in-time photometry the rotation period of an asteroid is not apriori known and a huge parameter space must be densely scanned for the best solution. The nature of the problem makes it an ideal task to be solved by distributed computing - the period parameter space can be divided into small bins that can be scanned separately and then joined together to give the globally best solution. In the framework of the the project, we process asteroid photometric data from surveys together with asteroid lightcurves and we derive asteroid shapes and spin states. The algorithm is based on the lightcurve inversion method developed by Kaasalainen et al. (Icarus 153, 37, 2001). The enormous potential of distributed computing will enable us to effectively process also the data from future surveys (Large Synoptic Survey Telescope, Gaia mission, etc.). We also plan to process data of a synthetic asteroid population to reveal biases of the method. In our presentation, we will describe the project, show the first results (new models of asteroids), and discuss the possibilities of its further development. This work has been supported by the grant GACR P209/10/0537 of the Czech Science Foundation and by the Research Program MSM0021620860 of the Ministry of Education of the Czech Republic.

  11. Probable Disastrous Consequences of Collision Between Unknown Small (100 m) Asteroids with Known (Approximately 1 km) Near Earth Orbiting (NEO) Asteroids

    NASA Technical Reports Server (NTRS)

    Smalley, Larry

    2003-01-01

    The long-term stability of the Solar System is not well understood. Ironically its stability is taken for granted even though our knowledge of all the constituents [comets, asteroids. (The Asteroid Belt between Mars and Jupiter, Trojan Asteroids, Kuiper belt, Ort Cloud), planetoids, planets, moons, etc], and its long-term dynamics cannot be easily computed. At best one might say that the solar system is chaotic, but much of the time it seems to exists near a quasi-stationary state. An asteroid that passes near the Earth regularly returns with clock-like precision. Taking into account every known detail of its path through the solar system, its orbit is calculated forward thousands of years with no untoward calamity on the horizon. And then one day, this passive visitor slams into the Earth during a sunny afternoon picnic! Can this happen? Unfortunately, this is a real possibility in the ordinary history of the solar system. In fact our knowledge of the solar system in the small is sketchy, as will be pointed out. Events, which lie outside our awareness, can precipitate disasters that we may perceive when it's too late to launch effective counter measures. In this work, one such scenario is described and the direct consequences for the Earth are calculated.

  12. Radar Observations of Near-Earth and Main-Belt Asteroids

    NASA Astrophysics Data System (ADS)

    Benner, L. A. M.; Busch, M. W.; Giorgini, J. D.; Taylor, P. A.; Margot, J.-L.

    Radar is a very powerful technique for characterizing near-Earth and main-belt asteroids and for improving their orbits. This results from radar's ability to spatially resolve objects that often cannot be resolved at comparable resolutions by other groundbased techniques. Radar has revealed binary and contact binary objects, at least two triple systems, non-principal-axis rotators, objects whose radar reflectivity and circular polarization ratio have longitudinal variation, irregularly shaped near-Earth asteroids, objects with metallic compositions, objects with rubble-pile structures, and detailed radar images of main-belt asteroids that reveal complicated surfaces and substantial topographic relief. This chapter concentrates on the most significant advances in the field since publication of the radar chapter by Ostro et al. (2002) in Asteroids III. Detailed descriptions of asteroid radar observing techniques and terminology have appeared in Ostro (1993) and Ostro et al. (2002) (Asteroids III), so we refer readers to those papers for background information. This chapter emphasizes the first ground-truth tests of asteroid shape models by spacecraft encounters, population trends among near-Earth and main-belt asteroids, results for selected objects, new observing techniques, improved capabilities at radar telescopes, and improvements in three-dimensional shape modeling. We conclude with a discussion of future prospects.

  13. The Double Asteroid Redirection Test (DART) for the AIDA Mission

    NASA Astrophysics Data System (ADS)

    Stickle, Angela; Cheng, Andy F.; Michel, Patrick; Barnouin, Olivier S.; Campo Bagatin, Adriano; Miller, Paul L.; Pravec, Petr; Richardson, Derek C.; Schwartz, Stephen R.; Tsiganis, Kleomenis; Ulamec, Stephan; AIDA Impact Modeling and Simulation Working Group

    2016-10-01

    The Asteroid Impact Deflection Assessment (AIDA) mission will be the first space experiment to demonstrate asteroid impact hazard mitigation using a kinetic impactor. AIDA is a joint ESA-NASA cooperative project, consisting of the NASA Double Asteroid Redirection Test (DART) mission, which provides the kinetic impactor, and the ESA Asteroid Impact Mission (AIM) rendezvous spacecraft. DART is a Phase A study supported by NASA, and AIM is a Phase B1 study supported by ESA. The AIDA target is the near-Earth binary asteroid 65803 Didymos, which will make a close approach to Earth in October, 2022. The DART spacecraft is designed to impact the Didymos secondary at ~6 km/s and deflect its trajectory, changing the orbital period of the binary. This change can be measured by Earth-based optical and radar observations. The primary goals of AIDA are to (1) perform a full-scale demonstration of asteroid deflection by kinetic impact; (2) measure the resulting deflection; and (3) validate and improve models for momentum transfer in high-speed impacts on an asteroid. The combined DART and AIM missions will provide the first measurements of momentum transfer efficiency from a kinetic impact at full scale on an asteroid, where the impact conditions of the projectile are known, and physical properties and internal structures of the target asteroid are also characterized. In addition to a predicted 4.4 minute change in the binary orbit period, assuming unit momentum transfer efficiency, the DART kinetic impact is predicted to induce forced librations of the Didymos secondary of possibly several degrees amplitude. Models predict the impact will create a 6-17 meter diameter crater, depending on target physical properties, and it will release a volume of particulate ejecta that may be directly observable from Earth or even resolvable as a coma or an ejecta tail by ground-based telescopes. Current simulations of the DART impact provide predictions for momentum transfer, crater size, and

  14. M-class Asteroids: Soft Rock, Heavy Metal, Or None Of That Jazz?

    NASA Astrophysics Data System (ADS)

    Rivkin, Andrew S.

    2008-09-01

    M-class asteroids in the Tholen taxonomy have featureless spectra in the 0.3-1.0 micrometer region and moderate albedos. Taxonomic studies using reflectance spectra have long associated M-class asteroids with iron meteorites. Dozens of parent bodies are required by cosmochemists in order to generate the diversity seen in the iron meteorite population, representing both the disrupted cores of differentiated parent bodies as well as objects with more exotic histories. Unfortunately, the featureless spectrum of iron-nickel metal in the visible and near-IR can be matched by other mineralogies unrelated to iron meteorites. For instance, the primitive enstatite chondrites are also matches to M asteroids (Burbine et al. 2002). The past 20 years have led to increased recognition that the M asteroid class includes a diverse set of objects. Polarimetric, spectral, and radar observations in the 1980s and 1990s showed that at least some M asteroids were not iron-meteorite-like. In particular, observations by Jones et al. (1990), Rivkin et al. (1995), and Rivkin et al. (2000) found several M asteroids with absorptions near 3 micrometers, interpreted as hydrated minerals. This led to the proposal to separate those asteroids with bands into a new W class. Since 2000, new observations have been made by various workers in the near and mid-IR from the ground and with Spitzer. An increase in the sample size of radar-detected asteroids has provided additional insight into M and W asteroids. New meteorite classes have been delimited and characterized, some of which are of direct relevance to the M asteroid population. Discoveries of binary M-class asteroids have allowed densities to be measured Finally, the Rosetta spacecraft will fly by the M (W) asteroid 21 Lutetia in 2010. I will discuss the M/W asteroid class in the context of all of these new data. Thanks to the NASA PAST and PGG programs.

  15. Standard Asteroid Photometric Catalogue

    NASA Astrophysics Data System (ADS)

    Piironen, J.; Lagerkvist, C.-I.; Torppa, J.; Kaasalainen, M.; Warner, B.

    2001-12-01

    The Asteroid Photometric Catalogue (APC) is now in its fifth update with over 8600 lightcurves of more than 1000 asteroids in the database. The APC also has references of over one thousand lightcurves not in digital format. The catalogue has been published by Uppsala University Observatory and is distributed by request (contact: classe@astro.uu.se). The new update also includes a list of known asteroid rotational periods and a CD-ROM containing all the existing digital data in the APC. The total number of observed lightcurves is growing rapidly, not the least because of the new state-of-the-art equipment and growing interest among amateur astronomers. The photometric database is now so large that the present format must be altered to facilitate a user-friendly on-line service for the down- and uploading of data. We are proposing (and have started to construct) a new Internet-based Standard Asteroid Photometric Catalogue (SAPC). The website is planned to open during the first half of the year 2002. In addition to the data files, the site would contain the index and guide to the catalogue, a web-form for reporting observations, and some general observing guidelines (e.g., on filters, timing, etc.). There would also be a list of asteroids for which more observations are needed, together with recommended observing periods. This would be accompanied by an up-to-date collection of physical asteroid models based on photometric data, as well as links to observer network pages and other sites that work in collaboration with the catalogue project. Our aim is to develop this site into a global standard service used by everyone involved in asteroid photometry.

  16. (25884) 2000 SQ4: A New Hungaria Binary?

    NASA Astrophysics Data System (ADS)

    Warner, Brian D.; Brinsfield, James W.; Vilagi, Jozef, Kornos, Leos; Harris, Alan W.

    2012-07-01

    CCD photometry observations of the Hungaria asteroid (25884) 2000 SQ4 were made at the Palmer Divide and Via Capote Observatories in 2011 November. This asteroid is of particular interest since it is part of an "asteroid pair", one of two asteroids believed to have once been a single object. Such pairs are believed to have been created due to fission after YORP spin up followed by the prompt ejection of the smaller body instead of it becoming a satellite. The two asteroids now occupy almost identical heliocentric orbits but do not circle one another. Analysis of the observations gives strong indications that 2000 SQ4 is a binary. If true, this would be the second member of an asteroid pair to have been found to have its own satellite.

  17. Genetic drift. Descent, lineage, and pedigree of the Trojans in Homer's Iliad.

    PubMed

    Bazopoulou-Kyrkanidou, Euterpe

    2007-12-15

    Homer's Iliad, is an epic poem that describes the last 70 days of the Trojan War, which was waged against the city of Troy by the Achaeans. Here, the descent, lineage, and the pedigree of the Trojans are presented. In the Illiad, they are said to have originated from Zeus. Beginning with him, the Trojan pedigree comprised 17 men in 8 generations with Dardanus, founder of Dardania in the second generation; Tros, King of the Trojans in the fourth generation; and the two heroes Hector and Aeneas in the eighth generation. In the seventh generation, Priam, as King of the Trojans, had a huge family, including 50 sons: 19 children with his wife Hecabe, other sons with many different wives, and some daughters as well. Hector, the first born, became leader of the Trojans. Hector's brother, Paris, in abducting Helen of Sparta, the wife of King Menelaus, caused the Trojan War to break out. PMID:17985360

  18. NASA Radar Images Asteroid Toutatis

    NASA Video Gallery

    This 64-frame movie of asteroid Toutatis was generated from data by Goldstone's Solar System Radar on Dec. 12 and 13, 2012. In the movie clips, the rotation of the asteroid appears faster than it o...

  19. Asteroid Redirect Mission: Crew Segment

    NASA Video Gallery

    NASA announced the next step in the plan to retrieve an asteroid boulder from a near-Earth asteroid and redirect it into a stable orbit around the moon to carry out human exploration missions, all ...

  20. CHAOTIC ZONES AROUND GRAVITATING BINARIES

    SciTech Connect

    Shevchenko, Ivan I.

    2015-01-20

    The extent of the continuous zone of chaotic orbits of a small-mass tertiary around a system of two gravitationally bound primaries of comparable masses (a binary star, a binary black hole, a binary asteroid, etc.) is estimated analytically, as a function of the tertiary's orbital eccentricity. The separatrix map theory is used to demonstrate that the central continuous chaos zone emerges (above a threshold in the primaries' mass ratio) due to overlapping of the orbital resonances corresponding to the integer ratios p:1 between the tertiary and the central binary periods. In this zone, the unlimited chaotic orbital diffusion of the tertiary takes place, up to its ejection from the system. The primaries' mass ratio, above which such a chaotic zone is universally present at all initial eccentricities of the tertiary, is estimated. The diversity of the observed orbital configurations of biplanetary and circumbinary exosystems is shown to be in accord with the existence of the primaries' mass parameter threshold.

  1. Primordial nucleosynthesis revisited via Trojan Horse Results

    NASA Astrophysics Data System (ADS)

    Pizzone, R. G.; Spartá, R.; Bertulani, C.; Spitaleri, C.; La Cognata, M.; Lamia, L.; Mukhamedzhanov, A.; Tumino, A.

    2016-05-01

    Big Bang Nucleosynthesis (BBN) requires several nuclear physics inputs and nuclear reaction rates. An up-to-date compilation of direct cross sections of d(d,p)t, d(d,n)3He and 3He(d,p)4He reactions is given, being these ones among the most uncertain bare-nucleus cross sections. An intense experimental effort has been carried on in the last decade to apply the Trojan Horse Method (THM) to study reactions of relevance for the BBN and measure their astrophysical S(E)-factor. The reaction rates and the relative error for the four reactions of interest are then numerically calculated in the temperature ranges of relevance for BBN (0.01

  2. THE EVOLUTION OF ASTEROIDS IN THE JUMPING-JUPITER MIGRATION MODEL

    SciTech Connect

    Roig, Fernando; Nesvorný, David E-mail: davidn@boulder.swri.edu

    2015-12-15

    In this work, we investigate the evolution of a primordial belt of asteroids, represented by a large number of massless test particles, under the gravitational effect of migrating Jovian planets in the framework of the jumping-Jupiter model. We perform several simulations considering test particles distributed in the Main Belt, as well as in the Hilda and Trojan groups. The simulations start with Jupiter and Saturn locked in the mutual 3:2 mean motion resonance plus three Neptune-mass planets in a compact orbital configuration. Mutual planetary interactions during migration led one of the Neptunes to be ejected in less than 10 Myr of evolution, causing Jupiter to jump by about 0.3 AU in semimajor axis. This introduces a large-scale instability in the studied populations of small bodies. After the migration phase, the simulations are extended over 4 Gyr, and we compare the final orbital structure of the simulated test particles to the current Main Belt of asteroids with absolute magnitude H < 9.7. The results indicate that, in order to reproduce the present Main Belt, the primordial belt should have had a distribution peaked at ∼10° in inclination and at ∼0.1 in eccentricity. We discuss the implications of this for the Grand Tack model. The results also indicate that neither primordial Hildas, nor Trojans, survive the instability, confirming the idea that such populations must have been implanted from other sources. In particular, we address the possibility of implantation of Hildas and Trojans from the Main Belt population, but find that this contribution should be minor.

  3. Geography of the asteroid belt

    NASA Technical Reports Server (NTRS)

    Zellner, B. H.

    1978-01-01

    The CSM classification serves as the starting point on the geography of the asteroid belt. Raw data on asteroid types are corrected for observational biases (against dark objects, for instance) to derive the distribution of types throughout the belt. Recent work on family members indicates that dynamical families have a true physical relationship, presumably indicating common origin in the breakup of a parent asteroid.

  4. Solar System binaries

    NASA Astrophysics Data System (ADS)

    Noll, Keith S.

    The discovery of binaries in each of the major populations of minor bodies in the solar system is propelling a rapid growth of heretofore unattainable physical information. The availability of mass and density constraints for minor bodies opens the door to studies of internal structure, comparisons with meteorite samples, and correlations between bulk-physical and surface-spectral properties. The number of known binaries is now more than 70 and is growing rapidly. A smaller number have had the extensive followup observations needed to derive mass and albedo information, but this list is growing as well. It will soon be the case that we will know more about the physical parameters of objects in the Kuiper Belt than has been known about asteroids in the Main Belt for the last 200 years. Another important aspect of binaries is understanding the mechanisms that lead to their formation and survival. The relative sizes and separations of binaries in the different minor body populations point to more than one mechanism for forming bound pairs. Collisions appear to play a major role in the Main Belt. Rotational and/or tidal fission may be important in the Near Earth population. For the Kuiper Belt, capture in multi-body interactions may be the preferred formation mechanism. However, all of these conclusions remain tentative and limited by observational and theoretical incompleteness. Observational techniques for identifying binaries are equally varied. High angular resolution observations from space and from the ground are critical for detection of the relatively distant binaries in the Main Belt and the Kuiper Belt. Radar has been the most productive method for detection of Near Earth binaries. Lightcurve analysis is an independent technique that is capable of exploring phase space inaccessible to direct observations. Finally, spacecraft flybys have played a crucial paradigm-changing role with discoveries that unlocked this now-burgeoning field.

  5. Effects of YORP-induced rotational fission on the small size end of the Main Belt asteroid size distribution

    NASA Astrophysics Data System (ADS)

    Rossi, Alessandro; Jacobson, S.; Marzari, F.; Scheeres, D.; Davis, D. R.

    2013-10-01

    From the results of a comprehensive asteroid population evolution model, we conclude that the YORP-induced rotational fission hypothesis has strong repercussions for the small size end of the Main Belt asteroid size frequency distribution. These results are consistent with observed asteroid population statistics. The foundation of this model is the asteroid rotation model of Marzari et al. (2011), which incorporates both the YORP effect and collisional evolution. This work adds to that model the rotational fission hypothesis (i.e. when the rotation rate exceeds a critical value, erosion and binary formation occur). The YORP effect timescale for large asteroids with diameters D > ~6 km is longer than the collision timescale in the Main Belt, thus the frequency of large asteroids is determined by a collisional equilibrium (e.g. Bottke 2005), but for small asteroids with diameters D < ~6 km, the asteroid population evolution model confirms that YORP-induced rotational fission destroys small asteroids more frequently than collisions. Therefore, the frequency of these small asteroids is determined by an equilibrium between the creation of new asteroids out of the impact debris of larger asteroids and the destruction of these asteroids by YORP-induced rotational fission. By introducing a new source of destruction that varies strongly with size, YORP-induced rotational fission alters the slope of the size frequency distribution. Using the outputs of the asteroid population evolution model and a 1-D collision evolution model, we can generate this new size frequency distribution and it matches the change in slope observed by the SKADS survey (Gladman 2009). This agreement is achieved with both an accretional power-law or a truncated “Asteroids were Born Big” size frequency distribution (Weidenschilling 2010, Morbidelli 2009).

  6. The active asteroids

    NASA Astrophysics Data System (ADS)

    Jewitt, D.

    2014-07-01

    Active asteroids simultaneously possess the orbits of main-belt asteroids and the physical appearances of comets; they show transient dust comae and solar-radiation pressure-swept tails. Apart from the shear surprise at finding such strange objects in the asteroid belt, the active asteroids are scientifically interesting for several reasons. Although we are limited to scarcely more than a dozen examples, the active asteroids already reveal the distinct action of different physical processes, each previously unobserved and carrying big-picture importance for understanding the solar system. 1. IMPACT. An unambiguous asteroid-asteroid impact was observed in 2010, when a 30-m scale body struck 100-km diameter (596) Scheila. Direct observations of impacts hold scientific importance both by sampling this natural process at full scale (compared with laboratory impacts conducted at tiny scales) and because impact statistics will allow us to assess the erosion rate in the asteroid belt and the contribution of asteroid dust to the interplanetary medium. 2. CRITICAL ROTATION. Several objects have been observed in which the best explanation seems to lie with spin-up to critical periods, presumably (but not certainly) caused by YORP. Examples of both likely mass-shedding (P/2010 A2, P/2013 P5) and full break-up (P/2013 R3, shown below) exist. It has been suggested that, at sub-kilometer sizes, spin-up disruption rates may surpass impact disruption rates. Future observations will show whether or not this is true, and may ultimately lead to an improved understanding of the physics of break-up. 3. THERMAL DISINTEGRATION. Geminid parent (3200) Phaethon shows on-going mass-loss at perihelion, driven by the 1000-K surface temperatures found there. The mechanisms appear to be some combination of thermal fracture and desiccation stress. 4. SUBLIMATION. Two objects have shown repeated activity that appears to be correlated with position in the orbit. The best example is 133P, which has

  7. The classification of asteroids

    NASA Astrophysics Data System (ADS)

    Davies, J. K.; Eaton, N.; Green, S. F.; McCheyne, R. S.; Meadows, A. J.

    A numerical taxonomy of asteroids is proposed and illustrated for a sample of 82 well-characterized asteroids in the TRIAD file described by Zellner (1979). The growth of different classification schemes, reflecting the rapid increase in knowledge of the physical and orbital properties of asteroids, is traced since about 1970. The proposed system is adapted from a microbiological taxonomy program and uses only physical parameters: albedo, red/blue ratio, visible-spectrum curvature, Fe(2+) absorption near 0.9 microns, U-B, and B-V. A dendrogram is presented and interpreted, and the scheme is found to agree reasonably well with conventional classifications, to allow the incorporation of new kinds of data, and to facilitate the identification of objects with particular charcteristics to plan future observations.

  8. 5426 Sharp: A Probable Hungaria Binary

    NASA Astrophysics Data System (ADS)

    Warner, Brian D.; Benishek, Vladimir; Ferrero, Andrea

    2015-07-01

    Initial CCD photometry observations of the Hungaria asteroid 5426 Sharp in 2014 December and 2015 January at the Center of Solar System Studies-Palmer Divide Station in Landers, CA, showed attenuations from the general lightcurve, indicating the possibility of the asteroid being a binary system. The secondary period was almost exactly an Earth day, prompting a collaboration to be formed with observers in Europe, which eventually allowed establishing two periods: P1 = 4.5609 ± 0.0003 h, A1 = 0.18 ± 0.01 mag and P2 = 24.22 ± 0.02 h, A2 = 0.08 ± 0.01 mag. No mutual events, i.e., occultations and/or eclipses, were seen, therefore the asteroid is considered a probable and not confirmed binary

  9. The Binary Nature of 8077 Hoyle

    NASA Astrophysics Data System (ADS)

    Klinglesmith, Daniel A.; Hendrickx, Sebastian

    2016-07-01

    Analysis of CCD photometric observations of 8077 Hoyle shows that it is a binary asteroid with a synodic period for the primary of 2.746 ± 0.001 h and an orbital period of 53.862 ± 0.026 h. The amplitude of the primary lightcurve is 0.18 mag.

  10. Asteroid Control and Resource Utilization

    NASA Astrophysics Data System (ADS)

    Paterson, G.; Radice, G.; Sanchez, J.-P.

    Asteroids are materials rich small solar system bodies which are prime candidates for rendezvous and mining. Up until now much attention has been focused on methods of destroying or deflecting potentially hazardous asteroids from colliding with the Earth. Recently however the concept of asteroid capture has been suggested whereby the asteroid is returned to an orbit close to the Earth before mining can begin. This paper aims to provide a comprehensive introduction to the field for new researchers and to put forward a number of novel strategies for asteroid control.

  11. Asteroid science by Gaia

    NASA Astrophysics Data System (ADS)

    Muinonen, Karri; Cellino, Alberto; Dell Oro, Aldo; Tanga, Paolo; Delbo, Marco; Mignard, Francois; Thuillot, William; Berthier, Jerome; Carry, Benoit; Hestroffer, Daniel; Granvik, Mikael; Fedorets, Grigori

    2016-07-01

    Since the start of its regular observing program in summer 2014, the Gaia mission has carried out systematic photometric, spectrometric, and astrometric observations of asteroids. In total, the unique capabilities of Gaia allow for the collection of an extensive and homogeneous data set of some 350,000 asteroids down to the limiting magnitude of G = 20.7 mag. The Gaia performance remains excellent over the entire available brightness range. Starting from 2003, a working group of European asteroid scientists has explored the main capabilities of the mission, defining the expected scientific impact on Solar System science. These results have served as a basis for developing the Gaia data reduction pipeline, within the framework of the Data Processing and Analysis Consortium (DPAC). We describe the distribution of the existing and forecoming Gaia observations in space and time for different categories of objects. We illustrate the peculiar properties of each single observation, as these properties will affect the subsequent exploitation of the mission data. We will review the expected performances of Gaia, basically as a function of magnitude and proper motion of the sources. We will further focus on the areas that will benefit from complementary observational campaigns to improve the scientific return of the mission, and on the involvement of the planetary science community as a whole in the exploitation of the Gaia survey. We will thus describe the current and future opportunities for ground-based observers and forthcoming changes brought by Gaia in some observational approaches, such as stellar occultations by transneptunian objects and asteroids. We will show first results from the daily, short-term processing of Gaia data, all the way from the onboard data acquisition to the ground-based processing. We illustrate the tools developed to compute predictions of asteroid observations, we discuss the procedures implemented by the daily processing, and we illustrate

  12. Herschel observations of the Marco Polo-R asteroid 175706 (1996 FG3).

    NASA Astrophysics Data System (ADS)

    O'Rourke, L.; Barucci, A.; Gònzalez-Garcìa, B.; Dotto, E.; Küppers, M.

    2012-09-01

    Background: The Marco Polo-R mission has been selected for the assessment study phase of the ESA M3 missions. This ESA-led sample return mission to the binary asteroid 1996 FG3 (launch window between 2020 and 2024) is proposed with a design that allows it to fit within the pre-defined cost cap of a M-class mission. The binary nature of the target will allow more precise measurements of mass, gravity, and density than for a single object, as well as additional insights into the geology and geophysics of the system. The asteroid has been classified by Binzel et al. [1] as a C-type. It is considered to be a typical example of a primitive object [2]. Dynamically, this is an Apollo asteroid with semimajor axis a of 1.054 AU, eccentricity e of 0.35, and and inclination i of 1.98 degrees. Measurements of the albedo derived from thermal infrared observations give a value of pV = 0.042 (+0.035 -0.017), and a combined diameter of D = 1.84 (+0.56 -0.47) km [3]. The Herschel observations : The MACH-11 (Measurements of 11 Asteroids & Comets) Programme observed this binary asteroid in two occasions in November of 2012. The observations performed had a duration of 0.6 hours with the asteroid pair moving rapidly at 6'/hr thus making removal of the background quite straightforward. The observations were performed in two observing blocks; the first block consisted of a 2 repetition blue/red map, the second block consisted of a 2 repetition green/red map, with the intention to observe the target at different phase angles. Our Results : Our measurements will serve to update the known radiometric properties for this binary asteroid through their inclusion into a thermophysical model (TPM) [4] which has been validated against a large database of asteroids including targets of other spacecraft mission e.g. Lutetia [5], Itokawa [6]. Using existing sets of published thermal observations (Spitzer, TNG NICS), combined with our Herschel observations, applied within this thermophysical model

  13. Comparing near-surface and bulk densities of asteroids using radar scattering properties

    NASA Astrophysics Data System (ADS)

    Zambrano Marin, Luisa Fernanda; Nolan, Michael C.; Taylor, Patrick A.; Virkki, Anne

    2016-10-01

    Dual-polarization radar measurements of asteroids provide a joint constraint on the near-surface density and porosity, which can give insights on asteroid composition and evolution. Magri et al. (2001) used (433) Eros radar and spacecraft data as calibration for estimating the near-surface densities and porosities of 45 other radar-detected asteroids (36 main-belt and 9 near-Earth). At that time, only (433) Eros had both radar observations and a measured bulk density. Now that there have been spacecraft observations of several other asteroids and radar measurements of the densities of several binary near-Earth asteroids with various compositions, we can expand the calibration to include those objects. We begin by applying the method of Magri et al. to Ceres, Vesta, Itokawa, 1994 CC, 2001 SN263, 1998 QE2, and 2000 DP107 to explore the differences between the bulk density and the near-surface density measured with radar. We expect significant differences between Ceres and Vesta and the small near-Earth asteroids as the porosities of these objects are expected to be quite different. However, we expect that small binary objects likely have similar internal structures, so that any differences should depend on composition and perhaps surface weathering.Reference: Magri et al., "Radar constraints on asteroid Properties using 433 Eros as ground truth". Meteoritics & Planetary Science 36, 1697-1709, 2001.

  14. A Geophysical Laboratory for Rubble Pile Asteroids: The BASiX Mission

    NASA Astrophysics Data System (ADS)

    Scheeres, Daniel J.; Chesley, Steven; Anderson, Robert C.

    2014-11-01

    Small rubble pile asteroids exhibit a diverse range of evolutionary behaviors and morphologies, driven by an array of poorly understood geophysical effects. The complex ways that these bodies evolve belies their simple structure: gravitational aggregates of shattered primitive bodies. Their evolution can be dramatic, such as seen in the active asteroids P/2013 P5 and P/2013 R3, or may be subtly masked, such as in the tide-BYORP equilibria of singly-synchronous binary asteroids. Their evolutionary outcomes can defy the imagination, such as asteroid 1950 DA which is spinning faster than its gravitational attraction yet is held together by weak van der Waals forces (Rozitis et al. 2014), or present us with profound mysteries, such as how the Almahata Sitta meteorite could be comprised of such diverse components. Beyond these motivations, the study of rubble pile asteroid geophysics can shed insight into any solar system environment where gravitational aggregates interact in a micro-gravity setting, ranging from the protoplanetary disc to planetary ring systems. The broad study of the geophysics of aggregates in such micro-gravity environments is becoming both a unifying theme and emerging field of study. Out of the many diverse and complex forms that rubble pile asteroids take on, the study of NEA binary asteroids can in particular be used to expose the geophysics of micro-gravity aggregates. Binaries are an expression of micro-gravity geophysics due to the manner in which they form and their continuing evolution. Due to our ability to visit, probe and interact with NEA, we can also turn them into geophysical laboratories. This talk will introduce the science of the Binary Asteroid in-situ Explorer (BASiX) Discovery mission, which proposes to turn the primitive C-Type binary asteroid (175706) 1996 FG3 into such a geophysical laboratory. Exploring this body enables us to probe a broad range of rubble pile asteroid properties: internal tidal dissipation (through FG3

  15. The Asteroid Frontier

    NASA Technical Reports Server (NTRS)

    Mcfadden, Lucyann A.

    2012-01-01

    There are many ways of studying the Asteroid Frontier as a scientist. In my career, I have used large telescopes atop a 14,000 ft mountain top observatory in Hawaii, used the Hubble Space Telescope in orbit around the Earth, traveled to Antarctica to collect meteorites sitting on the ice waiting for them to be recovered by scientists for scientific investigation, walked the desert with 50 students from University of Khartoum searching for fragments of an asteroid that collided with earth, exploded in the upper atmosphere and rained fragments on the desert floor. Most recently, I have looked at one of the largest Main Belt Asteroids named (4) Vesta through the eyes of a robotic spacecraft named Dawn, exploring the asteroid frontier. I will share my adventures, place the thrill of scientific exploration through NASA's solar system exploration program in context and provide opportunities for students to engage in NASA's exciting missions to expand scientific understanding of Earth and the Universe in which we live

  16. Asteroidal and planetary analysis

    NASA Technical Reports Server (NTRS)

    Hartmann, W. K.

    1975-01-01

    Photometric, spectrophotometric, and radiometric investigations of asteroids and planets are reported. Profiles of the planetary disk were used to study the physical structure of the Uranus atmosphere, and thermal and photographic properties of Saturn rings were theoretically modelled. Ground-based Mars observations were made for long-term comparison with Mariner 9 results.

  17. THE ACTIVE ASTEROIDS

    SciTech Connect

    Jewitt, David

    2012-03-15

    Some asteroids eject dust, unexpectedly producing transient, comet-like comae and tails. First ascribed to the sublimation of near-surface water ice, mass-losing asteroids (also called 'main-belt comets') can in fact be driven by a surprising diversity of mechanisms. In this paper, we consider 11 dynamical asteroids losing mass, in nine of which the ejected material is spatially resolved. We address mechanisms for producing mass loss including rotational instability, impact ejection, electrostatic repulsion, radiation pressure sweeping, dehydration stresses, and thermal fracture, in addition to the sublimation of ice. In two objects (133P and 238P) the repetitive nature of the observed activity leaves ice sublimation as the only reasonable explanation, while in a third ((596) Scheila), a recent impact is the cause. Another impact may account for activity in P/2010 A2, but this tiny object can also be explained as having shed mass after reaching rotational instability. Mass loss from (3200) Phaethon is probably due to cracking or dehydration at extreme ({approx}1000 K) perihelion temperatures, perhaps aided by radiation pressure sweeping. For the other bodies, the mass-loss mechanisms remain unidentified, pending the acquisition of more and better data. While the active asteroid sample size remains small, the evidence for an astonishing diversity of mass-loss processes in these bodies is clear.

  18. Asteroids, Comets, Meteors 1991

    NASA Technical Reports Server (NTRS)

    Harris, Alan W. (Editor); Bowell, Edward (Editor)

    1992-01-01

    Papers from the conference are presented and cover the following topics with respect to asteroids, comets, and/or meteors: interplanetary dust, cometary atmospheres, atmospheric composition, comet tails, astronomical photometry, chemical composition, meteoroid showers, cometary nuclei, orbital resonance, orbital mechanics, emission spectra, radio astronomy, astronomical spectroscopy, photodissociation, micrometeoroids, cosmochemistry, and interstellar chemistry.

  19. 5. TROJAN MILL, PRIMARY THICKENER No. 1 FROM WEST, c. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. TROJAN MILL, PRIMARY THICKENER No. 1 FROM WEST, c. 1914. TANK BARREL IS COMPLETE, BUT ADDITION ENCLOSURE NOT YET BEGUN. SAMPLING ADDITION SOUTH OF CRUSHED ORE BIN (CHANGE OF SIDING COLOR SHOWN AS COMPLETE. ROCK BIN VISIBLE ON FAR RIGHT. CREDIT WR. - Bald Mountain Gold Mill, Nevada Gulch at head of False Bottom Creek, Lead, Lawrence County, SD

  20. 6. TROJAN MILL, PRIMARY THICKENER No. 1 FROM WEST, c. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. TROJAN MILL, PRIMARY THICKENER No. 1 FROM WEST, c. 1914. TANK COMPLETED PRIOR TO ADDITION OF ENCLOSURE. ADDITION FOR BARREN SOLUTION TANK JUST VISIBLE BETWEEN THICKENER AND CRUSHED ORE BIN. CREDIT WR. - Bald Mountain Gold Mill, Nevada Gulch at head of False Bottom Creek, Lead, Lawrence County, SD

  1. 10. TROJAN MILL, EXTERIOR FROM EAST, c. 191928. ADDITION TO ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. TROJAN MILL, EXTERIOR FROM EAST, c. 1919-28. ADDITION TO THE EAST END OF MILLING FLOOR VISIBLE WITH TRAM ENTRY DOOR. ALSO SEEN ARE THE ADDITIONS FOR MILL SOLUTION TANKS AND THE EAST SIDE OF SAMPLING ROOMS. CREDIT JW. - Bald Mountain Gold Mill, Nevada Gulch at head of False Bottom Creek, Lead, Lawrence County, SD

  2. 13. TROJAN MILL, INTERIOR SHOWING PRIMARY MILL No. 1 (ALLIS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    13. TROJAN MILL, INTERIOR SHOWING PRIMARY MILL No. 1 (ALLIS CHALMERS BALL MILL) FROM EAST, c. 1919. ELECTRIC MOTOR AND DRIVE SHAFT CLEARLY VISIBLE. CREDIT WR. - Bald Mountain Gold Mill, Nevada Gulch at head of False Bottom Creek, Lead, Lawrence County, SD

  3. Coding as a Trojan Horse for Mathematics Education Reform

    ERIC Educational Resources Information Center

    Gadanidis, George

    2015-01-01

    The history of mathematics educational reform is replete with innovations taken up enthusiastically by early adopters without significant transfer to other classrooms. This paper explores the coupling of coding and mathematics education to create the possibility that coding may serve as a Trojan Horse for mathematics education reform. That is,…

  4. Asteroid (90) Antiope: Another icy member of the Themis family?

    NASA Astrophysics Data System (ADS)

    Hargrove, Kelsey D.; Emery, Joshua P.; Campins, Humberto; Kelley, Michael S. P.

    2015-07-01

    Many members of the Themis family show evidence of hydration in the form of oxidized iron in phyllosilicates (Florczak, M. et al. [1999]. Astron. Astrophys. Suppl. Ser. 134, 463-471), and OH-bearing minerals (Takir, D., Emery, J.P. [2012]. Icarus 219, 641-654). The largest member, (24) Themis, has H2O ice covering its surface (Campins, H. et al. [2010]. Nature 464, 1320-1321; Rivkin, A.S., Emery, J.P. [2010]. Nature 464, 1322-1323). We have investigated the second largest Themis-family asteroid, (90) Antiope, which Castillo-Rogez and Schmidt (Castillo-Rogez, J.C., Schmidt, B.E. [2010]. Geophys. Res. Lett. 37, L10202) predict to have a composition that includes water ice and organics. We obtained 2-4-μm spectroscopy of (90) Antiope in 2006 and 2008, and we find an absorption in the 3-μm region clearly present in our 2008 spectrum and likely in our 2006 spectrum. Both spectra have rounded, bowl-shaped absorptions consistent with those ascribed to water ice as in the spectrum of Asteroid (24) Themis. We also present and compare Spitzer 8-12-μm mid-infrared spectra of (24) Themis and (90) Antiope. We find that (90) Antiope is lacking a "fairy castle" dusty surface, which is in contrast to (24) Themis, other Themis family members (Licandro, J. et al. [2012]. Astron. Astrophys. 537, A73), and Jupiter Trojans (e.g. Emery, J.P., Cruikshank, D.P., Van Cleve, J. [2006]. Icarus 182, 496-512). We conclude that the surface structure of (90) Antiope is most similar to Cybele Asteroid (121) Hermione (Hargrove, K.D. et al. [2012]. Icarus 221, 453-455).

  5. (3749) BALAM: A VERY YOUNG MULTIPLE ASTEROID SYSTEM

    SciTech Connect

    Vokrouhlicky, David

    2009-11-20

    Binaries and multiple systems among small bodies in the solar system have received wide attention over the past decade. This is because their observations provide a wealth of data otherwise inaccessible for single objects. We use numerical integration to prove that the multiple asteroid system (3749) Balam is very young, in contrast to its previously assumed age of 0.5-1 Gyr related to the formation of the Flora family. This work is enabled by a fortuitous discovery of a paired component to (3749) Balam. We first show that the proximity of the (3749) Balam and 2009 BR60 orbits is not a statistical fluke of otherwise quasi-uniform distribution. Numerical integrations then strengthen the case and allow us to prove that 2009 BR60 separated from the Balam system less than a million years ago. This is the first time the age of a binary asteroid can be estimated with such accuracy.

  6. Olivine-rich asteroids in the main asteroid belt

    NASA Astrophysics Data System (ADS)

    DeMeo, Francesca E.; Polishook, David; Carry, Benoit; Moskovitz, Nick; Burt, Brian; Binzel, Rick

    2015-11-01

    Olivine-dominated asteroids, classified as A-types with near-infrared spectral measurements are largely thought to be the mantle remnants of disrupted differentiated small bodies. These A-type asteroids hold clues to asteroid differentiation and to the collisional history of those differentiated bodies. Preliminary studies of the abundance and distribution of A-type asteroids were performed by Carvano et al. (2010) and DeMeo & Carry (2013, 2014) using the Sloan Digital Sky Survey (SDSS). To confidently identify these olivine-dominated A-type asteroids, however, near-infrared spectral measurements are needed to identify the distinct broad and deep 1-micron olivine absorption feature. Using the Sloan Digital Sky Survey Moving Object Catalog to select A-type asteroid candidates, we have performed a near-infrared spectral survey of over 70 asteroids with SpeX on the IRTF. We present the abundance and distribution of A-type asteroids throughout the main asteroid belt and compare these results with similar surveys for basalt-rich V-type asteroids (e.g. Moskovitz et al. 2008). This work is supported by NASA under grant number NNX12AL26G issued through the Planetary Astronomy Program.

  7. On The Possibility Of Large KBOs Being Injected Into The Outer Asteroid Belt

    NASA Astrophysics Data System (ADS)

    McKinnon, William B.

    2008-09-01

    In the "Nice model,” an enormous quantity of KBOs are injected into the outer asteroid belt, >2.6 AU (Levison et al., submitted). Most are dynamically lost or collisionally destroyed, yet the remnant of this embedded population may be the source of the D-type asteroids. This raises the issue of whether larger KBOs were also embedded, and what they would look like today (and can we tell?). It is interesting to note that Ceres, the largest asteroid, is not that different from what we imagine dwarf planet KBOs to be like: differentiated, ice-rich (0.72-0.77 anhydrous rock by mass), and possessing unusual surface chemistry. In Levison et al., large KBOs are not considered; the embedded distribution is truncated at 200-km diameter, and the large (bright) end of the size-frequency distribution follows a very steep power-law slope (at least -6.4 differential). This is done, apparently, in order prevent the Trojan population from acquiring large members. If we extend this distribution to larger sizes, using the observed power-law slope of the bright end of today's Kuiper belt (about -4.5; Petit et al., in "The Solar System Beyond Neptune"), the probability of the outer asteroid belt acquiring a "Ceres” is a few percent; if the steep power-law component of Levison et al. is adjusted to the arguably more correct value, this probability rises to 10%. Large embedded asteroids are immune to collisional destruction, but they are subject to dynamical ejection. The probability of Ceres being a refugee from the Kuiper belt would appear to be small, but perhaps it was not as easily ejected as its much smaller D-type brethren. Regardless, its survival in the extreme collisional environment implied above implies bulk ice loss. The probability that one or more of the largest surviving asteroids came from the Kuiper belt should not be discounted.

  8. Asteroid Kinetic Impactor Missions

    NASA Astrophysics Data System (ADS)

    Chesley, Steven

    2015-08-01

    Asteroid impact missions can be carried out as a relatively low-cost add-ons to most asteroid rendezvous missions and such impact experiments have tremendous potential, both scientifically and in the arena of planetary defense.The science returns from an impactor demonstration begin with the documentation of the global effects of the impact, such as changes in orbit and rotation state, the creation and dissipation of an ejecta plume and debris disk, and morphological changes across the body due to the transmission of seismic waves, which might induce landslides and toppling of boulders, etc. At a local level, an inspection of the impact crater and ejecta blanket reveals critical material strength information, as well as spectral differences between the surface and subsurface material.From the planetary defense perspective, an impact demonstration will prove humankind’s capacity to alter the orbit of a potentially threatening asteroid. This technological leap comes in two parts. First, terminal guidance systems that can deliver an impactor with small errors relative to the ~100-200 meter size of a likely impactor have yet to be demonstrated in a deep space environment. Second, the response of an asteroid to such an impact is only understood theoretically due to the potentially significant dependence on the momentum carried by escaping ejecta, which would tend to enhance the deflection by tens of percent and perhaps as much as a factor of a few. A lack of validated understanding of momentum enhancement is a significant obstacle in properly sizing a real-world impactor deflection mission.This presentation will describe the drivers for asteroid impact demonstrations and cover the range of such concepts, starting with ESA’s pioneering Don Quijote mission concept and leading to a brief description of concepts under study at the present time, including the OSIRIS-REx/ISIS, BASiX/KIX and AIM/DART (AIDA) concepts.

  9. 2001 QR322: a dynamically unstable Neptune Trojan?

    NASA Astrophysics Data System (ADS)

    Horner, J.; Lykawka, P. S.

    2010-06-01

    Since early work on the stability of the first Neptunian Trojan, 2001 QR322, suggested that it was a dynamically stable, primordial body, it has been assumed that this applies to both that object and its more recently discovered brethren. However, it seems that things are no longer so clear-cut. In this work, we present the results of detailed dynamical simulations of the orbital behaviour of 2001 QR322. Using an ephemeris for the object that has significantly improved since earlier works, we follow the evolution of 19683 test particles, placed on orbits within the observational error ellipse of 2001 QR322's orbit, for a period of 1Gyr. We find that majority of these `clones' of 2001 QR322 are dynamically unstable, exhibiting a near-exponential decay from both the Neptunian Trojan cloud (decay half-life of ~550Myr) and the Solar system (decay half-life of ~590Myr). The stability of the object within Neptune's Trojan cloud is found to be strongly dependent on the initial semimajor axis used, with these objects located at a >= 30.30au being significantly less stable than those interior to this value, as a result of their having initial libration amplitudes very close to a critical threshold dividing regular and irregular motion, located at ~70°-75° (full extent of angular motion). This result suggests that if 2001 QR322 is a primordial Neptunian Trojan, it must be a representative of a population that was once significantly larger than that we see today and adds weight to the idea that the Neptune Trojans may represent a significant source of objects moving on unstable orbits between the giant planets (the Centaurs).

  10. Trojan Tour Enabled by Solar Electric Based Mission Architecture

    NASA Astrophysics Data System (ADS)

    Smith, David B.; Klaus, K.; Behrens, J.; Bingaman, G.; Elsperman, M.; Horsewood, J.

    2013-10-01

    Introduction: A Trojan Tour and Rendezvous mission was one of the missions recommended by the most recent Planetary Science Decadal Survey. To the greatest extent possible, we will utilize this concept as a basis for re-examining the feasibility of a Solar Electric Propulsion (SEP) mission using a Boeing bus and Advanced Modular Power System (AMPS) solar power generation. The concept study for the Decadal survey concluded that s SEP mission is not viable because of low solar intensity levels. Mission Overview: With the advent of the new high power solar array technology, SEP missions to the outer planets become viable. The mission objective is 1143 Odysseus, a Trojan within the Trojan cloud, consistent with the Decadal Survey. Our mission analysis using SEP yielded a 6 year travel time. The Decadal mission concept uses REP (Radioisotope Electric Propulsion) mission objective. For comparison, the REP mission concept flight time was 8 years. For the purposes of our study, the science payload instruments, data rates, mass and power requirements are identical to the Trojan Decadal study. Our investments focus on innovative lightweight structures, advanced solar array deployment systems, high voltage power systems, and high efficiency solar cells. Summary/Conclusion: By using advanced, high power generation solar arrays, SEP becomes a viable alternative for Jupiter system missions. We show that a SEP mission reduces the flight time to the Trojans by 2.5 years. We also show that a proven commercial bus can provide the necessary pointing accuracy and stability required for the Decadal mission concept and its science instrument suite.

  11. A Hypothesis for the Color Bimodality of Jupiter Trojans

    NASA Astrophysics Data System (ADS)

    Wong, Ian; Brown, Michael E.

    2016-10-01

    One of the most enigmatic and hitherto unexplained properties of Jupiter Trojans is their bimodal color distribution. This bimodality is indicative of two sub-populations within the Trojans, which have distinct size distributions. In this paper, we present a simple, plausible hypothesis for the origin and evolution of the two Trojan color sub-populations. In the framework of dynamical instability models of early solar system evolution, which suggest a common primordial progenitor population for both Trojans and Kuiper Belt objects, we use observational constraints to assert that the color bimodalities evident in both minor body populations developed within the primordial population prior to the onset of instability. We show that, beginning with an initial composition of rock and ices, location-dependent volatile loss through sublimation in this primordial population could have led to sharp changes in the surface composition with heliocentric distance. We propose that the depletion or retention of H2S ice on the surface of these objects was the key factor in creating an initial color bimodality. Objects that retained H2S on their surfaces developed characteristically redder colors upon irradiation than those that did not. After the bodies from the primordial population were scattered and emplaced into their current positions, they preserved this primordial color bimodality to the present day. We explore predictions of the volatile loss model—in particular, the effect of collisions within the Trojan population on the size distributions of the two sub-populations—and propose further experimental and observational tests of our hypothesis.

  12. Asteroid Analysis Using Lightcurve Photometry

    NASA Astrophysics Data System (ADS)

    Zimmerman, Jessica

    2011-10-01

    During the summer of 2011 data was taken of asteroid 3807 Pagels, a mid-sized asteroid located in the main asteroid belt in order to identify its rotational period. The asteroid 3807 Pagels is a poorly studied main belt asteroid that has little information recorded about its physical features. Time-series photometry of 3807 Pagels was obtained with a 16-inch telescope connected to a CCD camera located at the Texas A&M University - Commerce Observatory. CCD images were taken continuously with five minute exposure times through the standard broadband V filter. The data was then analyzed using the MPO Canopus program which utilized comparison stars within each CCD image to determine differential photometry and then generate a lightcurve for the asteroid. The final lightcurve did not show a complete rotational period for the asteroid. Thus, additional observations are needed in order to precisely determine 3807 Pagels rotational period. This research is the first steps of a long process of determining more information about the many mid-sized asteroids located in the asteroid belt for the potential of being able to classify these asteroids by their physical characteristics.

  13. Radar reconnaissance of near-Earth asteroids

    NASA Astrophysics Data System (ADS)

    Ostro, Steven J.; Giorgini, Jon D.; Benner, Lance A. M.

    2007-05-01

    Radar is a uniquely powerful source of information about near-Earth asteroid (NEA) physical properties and orbits. Measurements of the distribution of echo power in time delay (range) and Doppler frequency (radial velocity) constitute two-dimensional images that can provide spatial resolution finer than a decameter. The best radar images reveal geologic details, including craters and blocks. Radar wavelengths (13 cm at Arecibo, 3.5 cm at Goldstone) are sensitive to the bulk density (a joint function of mineralogy and porosity) and the degree of decimeter-scale structural complexity of the uppermost meter or so of the surface. Radar can determine the masses of binary NEAs via Kepler's third law and of solitary NEAs via measurement of the Yarkovsky acceleration. With adequate orientational coverage, a sequence of images can be used to construct a three-dimensional model, to define the rotation state, to determine the distribution of radar surface properties, and to constrain the internal density distribution. As of mid 2006, radar has detected echoes from 193 NEAs, of which 107 are designated Potentially Hazardous Asteroids. Radar has revealed both stony and metallic objects, principal-axis and non-principal-axis rotators, smooth and extremely rough surfaces, objects that appear to be monolithic fragments and objects likely to be nearly strengthless gravitational aggregates, spheroids and highly elongated shapes, contact-binary shapes, and binary systems. Radar can add centuries to the interval over which close Earth approaches can accurately be predicted, significantly refining collision probability estimates compared to those based on optical astrometry alone. If a small body is on course for a collision with Earth in this century, delay-Doppler radar echoes could almost immediately let us recognize this by distinguishing between an impact trajectory and a near miss, and would dramatically reduce the difficulty and cost of any effort to prevent the collision.

  14. ASTROMETRIC MASSES OF 26 ASTEROIDS AND OBSERVATIONS ON ASTEROID POROSITY

    SciTech Connect

    Baer, James; Chesley, Steven R.; Matson, Robert D. E-mail: steve.chesley@jpl.nasa.gov

    2011-05-15

    As an application of our recent observational error model, we present the astrometric masses of 26 main-belt asteroids. We also present an integrated ephemeris of 300 large asteroids, which was used in the mass determination algorithm to model significant perturbations from the rest of the main belt. After combining our mass estimates with those of other authors, we study the bulk porosities of over 50 main-belt asteroids and observe that asteroids as large as 300 km in diameter may be loose aggregates. This finding may place specific constraints on models of main-belt collisional evolution. Additionally, we observe that C-group asteroids tend to have significantly higher macroporosity than S-group asteroids.

  15. Asteroid Lightcurve Analysis at CS3-Palmer Divide Station: 2016 April-July

    NASA Astrophysics Data System (ADS)

    Warner, Brian D.

    2016-10-01

    Lightcurves for nine main-belt asteroids were obtained at the Center for Solar System Studies-Palmer Divide Station (CS3-PDS) from 2016 April to July. Of the group, four are known Hungaria binary asteroids: 1727 Mette, 2047 Smetana, 5899 Jedicke, and (18890) 2000 EV26. The Mars-crosser (54697) 2001 FA70 appears to be a newly-confirmed binary with P1 = 2.7075 h and POrb = 16.269 h. A third period, P2 = 2.1239 h, appears to be real. If so, it could be due to the asynchronous rotation of the satellite or a third body in the system.

  16. Shape-Based Thermal Modeling of Three Near-Earth Asteroids

    NASA Astrophysics Data System (ADS)

    Marshall, Sean; Vervack, Ronald J.; Magri, Christopher; Howell, Ellen S.; Fernandez, Yanga R.; Campbell, Donald B.; Nolan, Michael C.; Taylor, Patrick A.; Pollock, Joseph T.; Hicks, Michael D.

    2014-11-01

    Infrared observations of an asteroid can be used to estimate its size, albedo, thermal inertia, and other physical properties. However, these estimates are often based on thermal models that assume a spherical shape. Detailed shape information is only available for a small fraction of known asteroids, so making simplifying assumptions about the shape is often unavoidable. Nevertheless, it is important to quantify the errors that can arise from applying spherical thermal models to non-spherical asteroids. Here, we consider three near-Earth asteroids for which detailed radar- and lightcurve-based shape models are available: (4769) Castalia, (8567) 1996 HW1, and (162421) 2000 ET70. All three have substantial concavities: Castalia and 1996 HW1 are elongated contact binaries, and 2000 ET70 is a spheroidal object with large ridges. We observed these asteroids from the NASA InfraRed Telescope Facility (IRTF), each at multiple phase angles, as part of our campaign to obtain both radar observations and infrared spectroscopy of near-Earth asteroids. With our shape-based thermophysical model, SHERMAN, we show the range of variations in the asteroids' infrared spectra due to changes in rotation phase and viewing geometry. We also compare the thermal properties derived using the asteroids' true shapes to the thermal properties and sizes that would be derived from applying spherical thermal models to the same observations.

  17. ASPIN: Research project on near-Earth asteroid photometry in frame of the ISON optical network

    NASA Astrophysics Data System (ADS)

    Molotov, Igor; Inasaridze, Raguli; Elenin, Leonid; Krugly, Yurij; Rumyantsev, Vasilij; Namkhai, Tungalag; Schmalz, Sergei; Tsogt-Ochir, Shijirbayar

    International Scientific Optical Network (ISON) represents one of largest systems specializing in observation of space objects. The main goal of project is observations of space debris. As an additional task the regular photometry of near-Earth asteroids (NEAs) is carried out using the network’s telescopes with apertures from 0.4 m up to 2.6 m (ASPIN project - Asteroid Search and Photometry Initiative). The photometry is aimed at getting lightcurves of asteroids for solving different tasks concerning with physical properties of these celestial bodies. The lightcurves have been obtained with a typical photometric accuracy of 0.01-0.03 mag. The main purpose of the observations is to study characteristics of asteroids such as rotation period, size and shape of the body, surface composition and other. It is expected to detect an influence of the YORP effect. Special attention is paid to the detection of binary asteroids. During 2013 the photometric observations have been carried out at 12 observatories during more than 250 nights which have been allowed to obtain the data on 40 NEAs as well as 15 main-belt asteroids. In result the rotation periods have been determined for 8 NEAs in the first time and refined for 10 NEAs. Two binary systems were discovered. Lightcurves of 11 main-belt asteroids with diameters less than 10 km (binary systems or members of small clusters) were obtained. Several of the observed asteroids were radar targets - between them the NEA (367943) Duende (or 2012 DA14), which was approached to the Earth in day of falling the Chelyabinsk meteor on February 23, 2013. The obtained results will be presented and perspectives of NEA photometry with ISON telescopes will be discussed.

  18. Multiple origins of asteroid pairs

    NASA Astrophysics Data System (ADS)

    Jacobson, Seth A.

    2016-01-01

    Rotationally fissioned asteroids produce unbound asteroid pairs that have very similar heliocentric orbits. Backward integration of their current heliocentric orbits provides an age of closest proximity that can be used to date the rotational fission event. Most asteroid pairs follow a predicted theoretical relationship between the primary spin period and the mass ratio of the two pair members that is a direct consequence of the YORP-induced rotational fission hypothesis. If the progenitor asteroid has strength, asteroid pairs may have higher mass ratios or faster rotating primaries. However, the process of secondary fission leaves the originally predicted trend unaltered. We also describe the characteristics of pair members produced by four alternative routes from a rotational fission event to an asteroid pair. Unlike direct formation from the event itself, the age of closest proximity of these pairs cannot generally be used to date the rotational fission event since considerable time may have passed.

  19. Material properties for asteroid deflection

    NASA Astrophysics Data System (ADS)

    Bruck Syal, M.; Bernier, J.; Chen, L.; Coppari, F.; Dearborn, D.; Herbold, E.; Howley, K.; Kraus, R.; Kumar, M.; Millot, M.; Owen, J. M.; Swift, D.; Wasem, J.; Mulford, R.; Root, S.; Cotto-Figueroa, D.; Asphaug, E.; Schultz, P.; Nuth, J.; Arnold, J.; Burkhard, C.; Dotson, J.; Lee, T.; Sears, D.; Miller, P.

    2015-06-01

    Impulsive strategies to prevent asteroid impacts depend upon knowledge of asteroidal material state and response at extreme conditions. Numerical modeling of kinetic impactor and nuclear ablation scenarios to deflect or disrupt asteroids reveals sensitivities to equation of state, strength, and porosity. We report advances in material models for asteroid mitigation simulations. Equation of state development focuses on asteroidal materials, such as hydrated silicates. Shock experiments are being performed to measure properties of meteoritic material; initial sample temperature can be controlled from 100-1000 K, important for different intercept scenarios. New constitutive models allow improved thermomechanical response predictions for porous asteroids. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  20. Planet-crossing asteroid survey

    NASA Technical Reports Server (NTRS)

    Wilder, P. D.

    1984-01-01

    The planet-crossing asteroid survey was begun in 1973 in order to study those asteroids which may intersect the orbits of the inner planets. Throughout the history of the survey, many of the various classes of asteroids were investigated. The near-Earth objects including the Apollo, Amor, and Aten families were studied in addition to asteroids whose orbits cross that of Mars, and some objects which are generally confined to the main belt. Observing was done on the 18 inch Schmidt telescope at the Palomar Mtn. Observatory. Typically, two consecutive photographs of a favorable field are taken. The exposure times of the films are usually twenty minutes and ten minutes, respectively. The telescope is guided at sidereal rate, so that asteroids will leave short trailed images. The films are then scanned for trails. By comparing the two films, the direction and approximate rate of motion of an asteroid may be determined.

  1. ASTER: A Brazilian Mission to an Asteroid.

    NASA Astrophysics Data System (ADS)

    Winter, O. C.; Macau, E. E. N.; de Campos Velho, H.; Carruba, V.

    2012-05-01

    The first Brazilian mission to an asteroid is being planned. The target is the asteroid 2001 SN263, which has a NEA orbit of class AMOR. The mission is scheduled to be launched in 2015, reaching the asteroid in 2019.

  2. Asteroid Impact Monitoring

    NASA Astrophysics Data System (ADS)

    Milani, A.

    2006-06-01

    Some asteroids and comets with Earth-crossing orbit may impact our planet, thus we need to be able to identify the cases which could have a dangerous close approach within a century. This must be done as soon as such an asteroid is discovered, allowing for follow up observations which might contradict the impact possibility, and in the worst case to organize mitigation, possibly including deflection. The mathematical problem of predicting possible impacts, even with very low probabilities, has been solved by our group in the last few years. This paper presents the basic theory of these impact prediction, and discusses how they are practically used in the impact monitoring systems now operational, in particular the CLOMON2 robot of the Universities of Pisa and Valladolid.

  3. Asteroid Ida Rotation Sequence

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This montage of 14 images (the time order is right to left, bottom to top) shows Ida as it appeared in the field of view of Galileo's camera on August 28, 1993. Asteroid Ida rotates once every 4 hours, 39 minutes and clockwise when viewed from above the north pole; these images cover about one Ida 'day.' This sequence has been used to create a 3-D model that shows Ida to be almost croissant shaped. The earliest view (lower right) was taken from a range of 240,000 kilometers (150,000 miles), 5.4 hours before closest approach. The asteroid Ida draws its name from mythology, in which the Greek god Zeus was raised by the nymph Ida.

  4. Modeling of Fragmentation of Asteroids

    NASA Technical Reports Server (NTRS)

    Agrawal, Parul; Prabhu, Dinesh K.; Carlozzi, Alexander; Hart, Kenneth; Bryson, Katie; Sears, Derek

    2015-01-01

    The objective of this study is to understand fragmentation and fracture of a given asteroid and mechanisms of break-up. The focus of the present work is to develop modeling techniques for stony asteroids in 10m-100m range to answer two questions: 1) What is the role of material makeup of an asteroid in the stress distribution? 2)How is stress distribution altered in the presence of pre-existing defects?

  5. Silicates in Alien Asteroids

    NASA Technical Reports Server (NTRS)

    2009-01-01

    This plot of data from NASA's Spitzer Space Telescopes shows that asteroid dust around a dead 'white dwarf' star contains silicates a common mineral on Earth. The data were taken primarily by Spitzer's infrared spectrograph, an instrument that breaks light apart into its basic constituents. The yellow dots show averaged data from the spectrograph, while the orange triangles show older data from Spitzer's infrared array camera. The white dwarf is called GD 40.

  6. Roles of Shape and Internal Structure in Rotational Disruption of Asteroids

    NASA Astrophysics Data System (ADS)

    Hirabayashi, Masatoshi; Scheeres, Daniel Jay

    2015-08-01

    An active research area over the last decade has been to explore configuration changes of rubble pile asteroids due to rotationally induced disruption, initially driven by the remarkable fact that there is a spin period threshold of 2 hr for asteroids larger than a few hundred meters in size. Several different disruption modes due to rapid rotation can be identified, as surface shedding, fission and failure of the internal structure. Relevant to these discussions are many observations of asteroid shapes that have revealed a diversity of forms such as oblate spheroids with equatorial ridges, strongly elongated shapes and contact binaries, to say nothing of multi-body systems. With consideration that rotationally induced deformation is one of the primary drivers of asteroid evolution, we have been developing two techniques for investigating the structure of asteroids, while accounting for their internal mechanical properties through plastic theory. The first technique developed is an analytical model based on limit analysis, which provides rigorous bounds on the asteroid mechanical properties for their shapes to remain stable. The second technique applies finite element model analysis that accounts for plastic deformation. Combining these models, we have explored the correlation between unique shape features and failure modes. First, we have been able to show that contact binary asteroids preferentially fail at their narrow necks at a relatively slow spin period, due to stress concentration. Second, applying these techniques to the breakup event of active asteroid P/2013 R3, we have been able to develop explicit constraints on the cohesion within rubble pile asteroids. Third, by probing the effect of inhomogeneous material properties, we have been able to develop conditions for whether an oblate body will fail internally or through surface shedding. These different failure modes can be tested by measuring the density distribution within a rubble pile body through

  7. Asteroids, Comets, Meteors 2014

    NASA Astrophysics Data System (ADS)

    Muinonen, K.; Penttilä, A.; Granvik, M.; Virkki, A.; Fedorets, G.; Wilkman, O.; Kohout, T.

    2014-08-01

    Asteroids, Comets, Meteors focuses on the research of small Solar System bodies. Small bodies are the key to understanding the formation and evolution of the Solar System, carrying signals from pre-solar times. Understanding the evolution of the Solar System helps unveil the evolution of extrasolar planetary systems. Societally, small bodies will be important future resources of minerals. The near-Earth population of small bodies continues to pose an impact hazard, whether it be small pieces of falling meteorites or larger asteroids or cometary nuclei capable of causing global environmental effects. The conference series entitled ''Asteroids, Comets, Meteors'' constitutes the leading international series in the field of small Solar System bodies. The first three conferences took place in Uppsala, Sweden in 1983, 1985, and 1989. The conference is now returning to Nordic countries after a quarter of a century. After the Uppsala conferences, the conference has taken place in Flagstaff, Arizona, U.S.A. in 1991, Belgirate, Italy in 1993, Paris, France in 1996, Ithaca, New York, U.S.A. in 1999, in Berlin, Germany in 2002, in Rio de Janeiro, Brazil in 2005, in Baltimore, Maryland, U.S.A. in 2008, and in Niigata, Japan in 2012. ACM in Helsinki, Finland in 2014 will be the 12th conference in the series.

  8. Near Earth asteroid rendezvous

    NASA Technical Reports Server (NTRS)

    1992-01-01

    The Spacecraft Design Course is the capstone design class for the M.S. in astronautics at the Naval Postgraduate School. The Fall 92 class designed a spacecraft for the Near Earth Asteroid Rendezvous Mission (NEAR). The NEAR mission uses a robotic spacecraft to conduct up-close reconnaissance of a near-earth asteroid. Such a mission will provide information on Solar System formation and possible space resources. The spacecraft is intended to complete a NEAR mission as a relatively low-budget program while striving to gather as much information about the target asteroid as possible. A complete mission analysis and detailed spacecraft design were completed. Mission analysis includes orbit comparison and selection, payload and telemetry requirements, spacecraft configuration, and launch vehicle selection. Spacecraft design includes all major subsystems: structure, electrical power, attitude control, propulsion, payload integration, and thermal control. The resulting spacecraft demonstrates the possibility to meet the NEAR mission requirements using existing technology, 'off-the-shelf' components, and a relatively low-cost launch vehicle.

  9. Stability of binaries. Part II: Rubble-pile binaries

    NASA Astrophysics Data System (ADS)

    Sharma, Ishan

    2016-10-01

    We consider the stability of the binary asteroids whose members are granular aggregates held together by self-gravity alone. A binary is said to be stable whenever both its members are orbitally and structurally stable to both orbital and structural perturbations. To this end, we extend the stability analysis of Sharma (Sharma [2015] Icarus, 258, 438-453), that is applicable to binaries with rigid members, to the case of binary systems with rubble members. We employ volume averaging (Sharma et al. [2009] Icarus, 200, 304-322), which was inspired by past work on elastic/fluid, rotating and gravitating ellipsoids. This technique has shown promise when applied to rubble-pile ellipsoids, but requires further work to settle some of its underlying assumptions. The stability test is finally applied to some suspected binary systems, viz., 216 Kleopatra, 624 Hektor and 90 Antiope. We also see that equilibrated binaries that are close to mobilizing their maximum friction can sustain only a narrow range of shapes and, generally, congruent shapes are preferred.

  10. Reconstructing the spin distributions of main-belt asteroids

    NASA Astrophysics Data System (ADS)

    Holsapple, K.

    2014-07-01

    spin. There are reasonable parameter choices that result in the average equilibrium curve consistent with the average spins, and with the resulting distributions centered along that curve. Then there is also a ''maximum equilibrium spin curve'' defined as the maximum possible spin an asteroid can attain, again as a function of asteroid size. That bounds the upper limit of asteroid spins, and has a downward power slope of 0.65. The fact that the maximum equilibrium curve intersection with the gravity limit curve occurs right at the 10 km upper bound of the data for binary asteroids strongly suggests that it is collision spin-up and not YORP that creates the spins that result in binaries. Finally, a single large impact into an asteroid with a pre-existing average spin can easily reduce its spin to near zero. That may explain the excess of slow spinners (as compared to Maxwellian) for the spin distributions of the asteroids with diameters larger than 10 km. These results and others will be presented at the conference.

  11. Both size-frequency distribution and sub-populations of the main-belt asteroid population are consistent with YORP-induced rotational fission

    NASA Astrophysics Data System (ADS)

    Jacobson, S.; Scheeres, D.; Rossi, A.; Marzari, F.; Davis, D.

    2014-07-01

    From the results of a comprehensive asteroid-population-evolution model, we conclude that the YORP-induced rotational-fission hypothesis has strong repercussions for the small size end of the main-belt asteroid size-frequency distribution and is consistent with observed asteroid-population statistics and with the observed sub-populations of binary asteroids, asteroid pairs and contact binaries. The foundation of this model is the asteroid-rotation model of Marzari et al. (2011) and Rossi et al. (2009), which incorporates both the YORP effect and collisional evolution. This work adds to that model the rotational fission hypothesis (i.e. when the rotation rate exceeds a critical value, erosion and binary formation occur; Scheeres 2007) and binary-asteroid evolution (Jacobson & Scheeres, 2011). The YORP-effect timescale for large asteroids with diameters D > ˜ 6 km is longer than the collision timescale in the main belt, thus the frequency of large asteroids is determined by a collisional equilibrium (e.g. Bottke 2005), but for small asteroids with diameters D < ˜ 6 km, the asteroid-population evolution model confirms that YORP-induced rotational fission destroys small asteroids more frequently than collisions. Therefore, the frequency of these small asteroids is determined by an equilibrium between the creation of new asteroids out of the impact debris of larger asteroids and the destruction of these asteroids by YORP-induced rotational fission. By introducing a new source of destruction that varies strongly with size, YORP-induced rotational fission alters the slope of the size-frequency distribution. Using the outputs of the asteroid-population evolution model and a 1-D collision evolution model, we can generate this new size-frequency distribution and it matches the change in slope observed by the SKADS survey (Gladman 2009). This agreement is achieved with both an accretional power-law or a truncated ''Asteroids were Born Big'' size-frequency distribution

  12. Orbital Measurement of Bulk Carbon, Hydrogen, Oxygen, and Sulfur of Carbonaceous Asteroids via High Energy Resolution Gamma-Ray Spectroscopy

    NASA Astrophysics Data System (ADS)

    Lim, Lucy F.; Starr, Richard D.; Evans, Larry G.; Parsons, Ann M.; Zolensky, Michael E.; Boynton, William V.; Thomas, Cristina A.

    2014-11-01

    Various populations of low-albedo asteroids (C-complex, D, and P spectral types) dominate the outer Main Asteroid Belt, Hildas, and Trojan clouds and are thought to be related to carbonaceous meteorites. However, carbonaceous meteorites are themselves a diverse group and it remains unclear which types represent which asteroids or asteroid populations. A high-energy-resolution (HPGe) gamma-ray spectroscopy (GRS) experiment on an asteroid orbiter would be sensitive to many of the elements that differentiate carbonaceous chondrite subclasses from each other and from the ureilites, including H, C, O, and S, in the outer ~20-50 cm of the asteroid surface. We have therefore conducted new simulations of the performance of a GRS experiment in orbit around asteroids with carbonaceous chondriticcompositions at levels of hydration ranging from CI-like 17 wt% structural water) to CO-like (<2 wt% structural water). Cosmic-ray interactions with the asteroid surfaces were modeled using the MCNPX Monte-Carlo radiation transport code. A spacecraft background (based on a Dawn-like spacecraft model) was also modeled using MCNPX: this included background due to direct GCR/spacecraft interactions as well as background due to asteroidal neutron flux on the spacecraft. A Dawn-like mission scenario was modeled withthe altitude equal to the asteroid radius for a 4.5-month low-orbit phase. The detector model was based on Mars Odyssey Gamma-Ray Spectrometer (MOGRS), the largest and most sensitive HPGe GRS flown to date. The spectra from the MCNPX output were broadened to a resolution based on the in-flight performance of MOGRS, FWHM = 4.1 keV at 1332 keV. Doppler broadening was also modeled where applicable. Line fluxes were then extracted from the combined background + asteroid spectrum and statistical uncertainties evaluated.We find that within 4.5 months the GRS can measure H/Si, O/Si, C/Si, and S/Si with sufficient precision to distinguish OH-rich CI and CM chondrites from drier CO

  13. A systematic search for undiscovered companions to near-Earth asteroids in radar images

    NASA Astrophysics Data System (ADS)

    Bowman, M. Oliver; Margot, Jean-Luc

    2015-11-01

    Radar observations have been paramount to the characterization of small (<20 km) Near-Earth Objects (NEOs), specifically with regards to asteroid trajectories, shapes, spins, and multi-component systems. Binary systems make up a sizable fraction (~16%) of the asteroid population in near-Earth space. Their formation process is understood to be rotational fission caused by the YORP effect. Possible outcomes of post-fission dynamics include contact binaries, tightly and loosely bound binaries, and asteroid pairs. Radar images have been used to identify asteroid satellites that orbit near the primary component, but relatively little attention has been paid to the detection of more distant satellites. We are conducting a systematic search for faint and/or distant satellites in the Arecibo radar data archive. To this end, we have developed a software package to identify candidate objects in radar images and to differentiate these candidates from background noise using statistical analysis; preliminary results of the search will be presented at the meeting. Possible future applications include systematic measurements of asteroid radar properties (e.g., Doppler and range extents) that could become part of an automated data reduction pipeline.

  14. Matching asteroid population characteristics with a model constructed from the YORP-induced rotational fission hypothesis

    NASA Astrophysics Data System (ADS)

    Jacobson, Seth A.; Marzari, Francesco; Rossi, Alessandro; Scheeres, Daniel J.

    2016-10-01

    From the results of a comprehensive asteroid population evolution model, we conclude that the YORP-induced rotational fission hypothesis is consistent with the observed population statistics of small asteroids in the main belt including binaries and contact binaries. These conclusions rest on the asteroid rotation model of Marzari et al. ([2011]Icarus, 214, 622-631), which incorporates both the YORP effect and collisional evolution. This work adds to that model the rotational fission hypothesis, described in detail within, and the binary evolution model of Jacobson et al. ([2011a] Icarus, 214, 161-178) and Jacobson et al. ([2011b] The Astrophysical Journal Letters, 736, L19). Our complete asteroid population evolution model is highly constrained by these and other previous works, and therefore it has only two significant free parameters: the ratio of low to high mass ratio binaries formed after rotational fission events and the mean strength of the binary YORP (BYORP) effect. We successfully reproduce characteristic statistics of the small asteroid population: the binary fraction, the fast binary fraction, steady-state mass ratio fraction and the contact binary fraction. We find that in order for the model to best match observations, rotational fission produces high mass ratio (> 0.2) binary components with four to eight times the frequency as low mass ratio (<0.2) components, where the mass ratio is the mass of the secondary component divided by the mass of the primary component. This is consistent with post-rotational fission binary system mass ratio being drawn from either a flat or a positive and shallow distribution, since the high mass ratio bin is four times the size of the low mass ratio bin; this is in contrast to the observed steady-state binary mass ratio, which has a negative and steep distribution. This can be understood in the context of the BYORP-tidal equilibrium hypothesis, which predicts that low mass ratio binaries survive for a significantly

  15. Trojan horse attacks on counterfactual quantum key distribution

    NASA Astrophysics Data System (ADS)

    Yang, Xiuqing; Wei, Kejin; Ma, Haiqiang; Sun, Shihai; Du, Yungang; Wu, Lingan

    2016-04-01

    There has been much interest in "counterfactual quantum cryptography" (T.-G. Noh, 2009 [10]). It seems that the counterfactual quantum key distribution protocol without any photon carrier through the quantum channel provides practical security advantages. However, we show that it is easy to break counterfactual quantum key distribution systems in practical situations. We introduce the two types of Trojan horse attacks that are available for the two-way protocol and become possible for practical counterfactual systems with our eavesdropping schemes.

  16. The deployment of scientific packages to asteroid surfaces

    NASA Astrophysics Data System (ADS)

    Tardivel, Simon Charles Vincent

    A strategy for the deployment of landers to asteroid surfaces is described. The landing pods are scientific packages with no guidance, navigation and control system, and no specific landing apparatus, so as to minimize onboard platform and maximize payload. The landers are jettisoned from a main spacecraft at high altitude over the target. They impact its surface, bouncing multiple times before finally coming to rest. The amended gravity field of an asteroid is described in general and regions favorable to a deployment are found close to saddle equilibrium points. For elongated bodies and for binary systems, a linearization shows that a branch of the unstable manifold intersects the surface of the body; the strategy then consists of choosing initial conditions that will express this branch. For quasi-axisymmetric bodies, the initial velocity of the lander is increased to guarantee an impact. The efficacy of the strategy is numerically verified. A model of the asteroid surface and of the interaction between the pod and this surface is detailed. The asteroid surface is represented with three layers. The asteroid is first modeled using a mesh of triangular facets that can represent its global shape down to the presence of large boulders (greater than 1m). The presence of smaller rocks is accounted for via a stochastic model that generates random collisions with rocks, at impact with the surface or during lasting contact motion (rolling). Finally the interaction with the regolith is handled with a model of contact dynamics, including surface forces and torques (reaction, friction and rolling resistance). The rolling resistance force and torques experienced on regolith are defined and justified. Their coefficients are measured by experiments and explained by theory and finite-element simulations. Practical mission case studies are presented and discussed, for asteroid Itokawa, 1999 JU3, 1999 KW4 Alpha and Beta.

  17. A Mobile Asteroid Surface Scout for the AIDA Mission

    NASA Astrophysics Data System (ADS)

    Ho, Tra Mi; Lange, Caroline; Grimm, Christian; Thimo Grundmann, Jan; Rößler, Johannes; Schröder, Silvio; Skoczylas, Thomas; Ziach, Christian; Biele, Jens; Cozzoni, Barbara; Krause, Christian; Küchemann, Oliver; Maibaum, Michael; Ulamec, Stephan; Lange, Michael; Mierheim, Olaf; Maier, Maximilian; Herique, Alain; Mascot Study Team

    2016-04-01

    The Asteroid Impact Deflection, AIDA, mission is composed of a kinetic impactor, DART and an observer, the Asteroid Impact Monitor, AIM, carrying among other payload a surface package, MASCOT2 (MSC2). Its proposed concept is based on the MASCOT lander onboard the HAYABUSA2 Mission (JAXA) to near-Earth asteroid (162173) Ryugu. MASCOT is a compact platform ('shoe box size') carrying a suite of 4 scientific instruments and has a landed mass of ~10kg. Equipped with a mobility mechanism, the MASCOT lander is able to upright and relocate on the targeted asteroid; thus providing in-situ data at more than one site. In the context of the AIDA Mission, the MASCOT2 lander would be carried by the AIM spacecraft and delivered onto Didymoon, the secondary object in the (65803) Didymos binary near-Earth asteroid system. Since the mission objectives of the AIM mission within the joint AIDA mission concept differ from JAXA's sample return mission HAYABUSA2, several design changes need to be studied and implemented. To support one of the prime objectives of the AIM mission, the characterization of the bulk physical properties of Didymoon, the main scientific payload of MSC2 is a low-frequency radar (LFR) to investigate the internal structure of the asteroid moon. Since the total science payload on MASCOT2 is limited to approximately 2.3 kg, the mass remaining for a suite of other experiments is in the range of 0.1 to 0.5 kg per instrument. Further requirements have a significant impact on the MSC2 design which will be presented. Among these are the much longer required operational lifetime than for MASCOT on HAYABUSA2, and different conditions on the target body such as an extremely low gravity due to its small size of Ø_[Didymoon] ~ 150m.

  18. Beyond injection: Trojan horse underdense photocathode plasma wakefield acceleration

    SciTech Connect

    Hidding, B.; Rosenzweig, J. B.; Xi, Y.; O'Shea, B.; Andonian, G.; Schiller, D.; Barber, S.; Williams, O.; Pretzler, G.; Koenigstein, T.; Kleeschulte, F.; Hogan, M. J.; Litos, M.; Corde, S.; White, W. W.; Muggli, P.; Bruhwiler, D. L.; Lotov, K.

    2012-12-21

    An overview on the underlying principles of the hybrid plasma wakefield acceleration scheme dubbed 'Trojan Horse' acceleration is given. The concept is based on laser-controlled release of electrons directly into a particle-beam-driven plasma blowout, paving the way for controlled, shapeable electron bunches with ultralow emittance and ultrahigh brightness. Combining the virtues of a low-ionization-threshold underdense photocathode with the GV/m-scale electric fields of a practically dephasing-free beam-driven plasma blowout, this constitutes a 4th generation electron acceleration scheme. It is applicable as a beam brightness transformer for electron bunches from LWFA and PWFA systems alike. At FACET, the proof-of-concept experiment 'E-210: Trojan Horse Plasma Wakefield Acceleration' has recently been approved and is in preparation. At the same time, various LWFA facilities are currently considered to host experiments aiming at stabilizing and boosting the electron bunch output quality via a trojan horse afterburner stage. Since normalized emittance and brightness can be improved by many orders of magnitude, the scheme is an ideal candidate for light sources such as free-electron-lasers and those based on Thomson scattering and betatron radiation alike.

  19. Modeling Asteroid Spin-up with Cohesion

    NASA Astrophysics Data System (ADS)

    Walsh, Kevin J.; Richardson, D. C.; Michel, P.

    2008-09-01

    Recent work has shown that the gradual spin-up of cohesionless gravitational aggregates produces a wide range of outcomes depending on the specific configuration of the body, such as particle size distribution. One important outcome is the creation of binary asteroids, which requires bodies that can maintain spherical/oblate shapes as the body is spun to rapid rotation (Walsh et al., 2008, Nature, 454, 188-191). Our recent work includes a similar model which also models cohesion within the gravitational aggregate by way of a spring-like restoring force between neighboring particles that vanishes under high strain. We will present early results of gradual spin-up tests on gravitational aggregates covering a large range of starting conditions including the initial body shape and size, as well as varying configurations for the cohesion properties. These results will be compared to previous spin-up work as well as analytical theory. KJW and PM had the support of the French Programme National de Planétologie and the ACT Team of ESA and Ariadna Study 07/4111"Asteroid Rotational Fragmentation". KJW is also supported by the Henri Poincaré fellowship at the Observatoire de la Côte d'Azur, Nice, France, and Rotary International -- District 1730. DCR acknowledges support from the National Science Foundation under grant AST0708110 and the National Aeronautics and Space Administration under Grant No. NNX08AM39G.

  20. Asteroids: Does Space Weathering Matter?

    NASA Technical Reports Server (NTRS)

    Gaffey, Michael J.

    2001-01-01

    The interpretive calibrations and methodologies used to extract mineralogy from asteroidal spectra appear to remain valid until the space weathering process is advanced to a degree which appears to be rare or absent on asteroid surfaces. Additional information is contained in the original extended abstract.

  1. Penetrometry on an asteroid

    NASA Astrophysics Data System (ADS)

    Paton, M.; Green, S.; Ball, A.; Zarnecki, J.

    2014-07-01

    An end-of-mission landing on a near-Earth asteroid (like the NEAR landing on Eros) offers the opportunity to make dynamic force measurements followed by extended thermal investigations of the subsurface using simple sensors housed inside or outside of a penetrometer fixed to the spacecraft body. Such measurements could provide useful information on the microstructural and thermal properties of the regolith [1,2]. The high mass (about 100 kg) and low landing speed (< 2 m s^{-1}) of the spacecraft will provide enough momentum to push a penetrometer into an asteroid regolith. To simulate the impact under the low gravity of the asteroid, where the strength of the material would dominate the impact dynamics, it is desirable to remove the effect of Earth's gravity from both the target and the penetrometer/spacecraft. A low speed, high momentum, penetrometer test rig, built at The Open University [3] effectively removes the gravitational force acting on the landing penetrometer/spacecraft, but not the target. This enables tests to be conducted with regolith analogues of lower strength than would otherwise be possible if the acceleration due to gravity was acting on the landing spacecraft. The rig has been used for conducting penetrometry [4] and thermal experiments [2] in a variety of planetary regolith analogues. Here we examine the advantages and disadvantages of using a small penetrometer that can easily penetrate the surface. We also examine the advantages and disadvantages of using a large, wide penetrometer, that could possibly decelerate the spacecraft before its base impacts the surface and compacts the regolith beneath it. Laboratory tests comparing the two penetrometers are presented with some realistic calculations for simulating a spacecraft landing with a non-zero horizontal speed.

  2. Asteroids and andesites.

    PubMed

    Arculus, Richard; Campbell, Ian H; McLennan, Scott M; Taylor, Stuart Ross

    2009-05-28

    The production of terrestrial andesites in subduction zones is well established. Day et al. describe two examples of meteorites (GRA 06128 and GRA 06129) that they claim to represent "an entirely new mode of generation of andesite crust compositions" on asteroids; this suggestion has wide implications for the generation of andesitic planetary crusts in general. However, here we show that compositional data, particularly for the rare-earth elements (REEs) and other lithophile elements, presented in their paper do not substantiate this claim. We conclude that existing mechanisms for andesite generation do not need revision.

  3. Migration of Asteroidal Dust

    NASA Technical Reports Server (NTRS)

    Ipatov, S. I.; Mather, J. C.

    2003-01-01

    Using the Bulirsh Stoer method of integration, we investigated the migration of dust particles under the gravitational influence of all planets, radiation pressure, Poynting Robertson drag and solar wind drag for equal to 0.01, 0.05, 0.1, 0.25, and 0.4. For silicate particles such values of correspond to diameters equal to about 40, 9, 4, 2, and 1 microns, respectively [1]. The relative error per integration step was taken to be less than 10sup-8. Initial orbits of the particles were close to the orbits of the first numbered mainbelt asteroids.

  4. Asteroids and andesites.

    PubMed

    Arculus, Richard; Campbell, Ian H; McLennan, Scott M; Taylor, Stuart Ross

    2009-05-28

    The production of terrestrial andesites in subduction zones is well established. Day et al. describe two examples of meteorites (GRA 06128 and GRA 06129) that they claim to represent "an entirely new mode of generation of andesite crust compositions" on asteroids; this suggestion has wide implications for the generation of andesitic planetary crusts in general. However, here we show that compositional data, particularly for the rare-earth elements (REEs) and other lithophile elements, presented in their paper do not substantiate this claim. We conclude that existing mechanisms for andesite generation do not need revision. PMID:19478728

  5. Multiple asteroid systems: Dimensions and thermal properties from Spitzer Space Telescope and ground-based observations

    NASA Astrophysics Data System (ADS)

    Marchis, F.; Enriquez, J. E.; Emery, J. P.; Mueller, M.; Baek, M.; Pollock, J.; Assafin, M.; Vieira Martins, R.; Berthier, J.; Vachier, F.; Cruikshank, D. P.; Lim, L. F.; Reichart, D. E.; Ivarsen, K. M.; Haislip, J. B.; LaCluyze, A. P.

    2012-11-01

    We collected mid-IR spectra from 5.2 to 38 μm using the Spitzer Space Telescope Infrared Spectrograph of 28 asteroids representative of all established types of binary groups. Photometric lightcurves were also obtained for 14 of them during the Spitzer observations to provide the context of the observations and reliable estimates of their absolute magnitudes. The extracted mid-IR spectra were analyzed using a modified standard thermal model (STM) and a thermophysical model (TPM) that takes into account the shape and geometry of the large primary at the time of the Spitzer observation. We derived a reliable estimate of the size, albedo, and beaming factor for each of these asteroids, representing three main taxonomic groups: C, S, and X. For large (volume-equivalent system diameter Deq > 130 km) binary asteroids, the TPM analysis indicates a low thermal inertia (Γ ⩽ ∼100 J s-1/2 K-1 m-2) and their emissivity spectra display strong mineral features, implying that they are covered with a thick layer of thermally insulating regolith. The smaller (surface-equivalent system diameter Deff < 17 km) asteroids also show some emission lines of minerals, but they are significantly weaker, consistent with regoliths with coarser grains, than those of the large binary asteroids. The average bulk densities of these multiple asteroids vary from 0.7-1.7 g/cm3 (P-, C-type) to ∼2 g/cm3 (S-type). The highest density is estimated for the M-type (22) Kalliope (3.2 ± 0.9 g/cm3). The spectral energy distributions (SEDs) and emissivity spectra, made available as a supplement document, could help to constrain the surface compositions of these asteroids.

  6. Multiple Asteroid Systems: Dimensions and Thermal Properties from Spitzer Space Telescope and Ground-based Observations

    NASA Technical Reports Server (NTRS)

    Marchis, F.; Enriquez, J. E.; Emery, J. P.; Mueller, M.; Baek, M.; Pollock, J.; Assafin, M.; Matins, R. Vieira; Berthier, J.; Vachier, F.; Cruikshank, D. P.; Lim, L. F.; Reichart, D. E.; Ivarsen, K. M.; Haislip, J. B.; LaCluyze, A. P.

    2012-01-01

    We collected mid-IR spectra from 5.2 to 38 microns using the Spitzer Space Telescope Infrared Spectrograph of 28 asteroids representative of all established types of binary groups. Photometric light curves were also obtained for 14 of them during the Spitzer observations to provide the context of the observations and reliable estimates of their absolute magnitudes. The extracted mid-IR spectra were analyzed using a modified standard thermal model (STM) and a thermophysical model (TPM) that takes into account the shape and geometry of the large primary at the time of the Spitzer observation. We derived a reliable estimate of the size, albedo, and beaming factor for each of these asteroids, representing three main taxonomic groups: C, S, and X. For large (volume-equivalent system diameter Deq > 130 km) binary asteroids, the TPM analysis indicates a low thermal inertia (Lambda < or = approx.100 J/1/2 s/K/sq m2) and their emissivity spectra display strong mineral features, implying that they are covered with a thick layer of thermally insulating regolith. The smaller (surface-equivalent system diameter Deff < 17 km) asteroids also show some emission lines of minerals, but they are significantly weaker, consistent with regoliths with coarser grains, than those of the large binary asteroids. The average bulk densities of these multiple asteroids vary from 0.7-1.7 g/cu cm (P-, C-type) to approx. 2 g/cu cm (S-type). The highest density is estimated for the M-type (22) Kalliope (3.2 +/- 0.9 g/cu cm). The spectral energy distributions (SEDs) and emissivity spectra, made available as a supplement document, could help to constrain the surface compositions of these asteroids.

  7. Discovery of a Satellite around a Near-Earth Asteroid

    NASA Astrophysics Data System (ADS)

    1997-07-01

    the data necessary for these determinations, observations will be continued during the present period of good visibility that lasts until September-October 1997. For this reason the discoverers have initiated an international observation campaign devoted to the study of this intriguing object and now involving astronomers from many countries. How common are such satellites? Satellites in orbit around small bodies in the solar system - asteroids and cometary nuclei - have been predicted on theoretical grounds for a long time, even though there is no consensus among planetary scientists about the actual numbers of such systems. Hints about the existence of asteroid satellites also come from the presence of double impact craters on the Moon and other planetary surfaces. This suggests that the projectiles forming these craters were `double' asteroids. Moreover, measurements obtained when an asteroid passes in front of a relatively bright star (a so-called `occultation') have on a few occasions shown features which could be interpreted as due to the presence of a satellite. However, because of the difficult nature of such measurements, it has never been possible to draw unambiguous conclusions. The existence of double asteroids was invoked earlier by Petr Pravec and Gerhard Hahn to explain the unusual features observed in the lightcurves of two other Earth-approaching asteroids 1991 VH and 1994 AW1 . In the case of Dionysus , however, it is possible to predict eclipse events and to confirm them by subsequent measurements. There is therefore mounting evidence that asteroid binary systems might be comparatively common. Observational programmes like the present one by the DLR and Ondrejov groups will help to verify this possibility. Where to find additional information Detailed and up-to-date information about (3671) Dionysus can be found in the Web at the following URL: http://earn.dlr.de/dionysus. Notes: [1] This institute and its parent organisation are known in Germany as

  8. 2008 LC18: a potentially unstable Neptune Trojan

    NASA Astrophysics Data System (ADS)

    Horner, J.; Lykawka, P. S.; Bannister, M. T.; Francis, P.

    2012-05-01

    The recent discovery of the first Neptune Trojan at the planet's trailing (L5) Lagrange point, 2008 LC18, offers an opportunity to confirm the formation mechanism of a member of this important tracer population for the Solar system's dynamical history. We tested the stability of 2008 LC18's orbit through a detailed dynamical study, using test particles spread across the ±3σ range of orbital uncertainties in a, e, i and Ω. This showed that the wide uncertainties of the published orbit span regions of both extreme dynamical instability, with lifetimes <100 Myr, and significant stability, with lifetimes >1 Gyr. The stability of 2008 LC18's clones is greatly dependent on their semimajor axis and only weakly correlated with their orbital eccentricity. Test particles on orbits with an initial semimajor axis of less than 29.91 au have dynamical half-lives shorter than 100 Myr; in contrast, particles with an initial semimajor axis of greater than 29.91 au exhibit such strong dynamical stability that almost all are retained over the 1 Gyr of our simulations. More observations of this object are necessary to improve the orbit. If 2008 LC18 is in the unstable region, then our simulations imply that it is either a temporary Trojan capture or a representative of a slowly decaying Trojan population (like its sibling the L4 Neptunian Trojan 2001 QR322), and that it may not be primordial. Alternatively, if the orbit falls into the larger, stable region, then 2008 LC18 is a primordial member of the highly stable and highly inclined component of the Neptune Trojan population, joining 2005 TN53 and 2007 VL305. We attempted to recover 2008 LC18 using the 2.3-m telescope at Siding Spring Observatory to provide this astrometry, but were unsuccessful due to the high stellar density of its current sky location near the Galactic centre. The recovery of this object will require a telescope in the 8-m class.

  9. Trojans and Plutinos as probes of planet building

    NASA Astrophysics Data System (ADS)

    Alexandersen, Mike; Gladman, B.; Kavelaars, J. J.; Petit, J.; Gwyn, S.; Greenstreet, S.

    2013-10-01

    Planetesimals formed during planet formation are the building blocks of giant planet cores; some are preserved as large trans-neptunian objects (TNOs). Previous work has shown steep power-law distributions for TNOs of diameters > 100 km. Recent results claim a dramatic roll-over or divot in the size distribution of Neptunian Trojans and scattering TNOs, with a significant lack of intermediate-size D<100 km planetesimals. One theoretical explanation for this is that planetesimals were born big, skipping the intermediate sizes, contrary to the classical understanding of planetesimal formation. Exploration of the TNO size distribution requires more precisely calibrated detections in order to improve statistics on these results. We have searched a 32 sq.deg. area near RA=2 hr to a r-band limiting magnitude of m_r=24.6 using the Canada-France-Hawaii Telescope. This coverage was near the Neptunian L4 region to maximise our detection rate, as this is where Trojans reside and where Plutinos (and several other resonant populations) come to perihelion. Our program successfully detected, tracked and characterized 77 TNOs and Centaurs for up to 17 months, giving us the high-quality orbits needed for precise modelling. Among our detections were one Uranian Trojan (see Alexandersen et al. 2013 & abstract by Greenstreet et al.), two Neptunian Trojans, 18 Plutinos and many other resonant objects. This meticulously calibrated survey and the high-quality orbits obtained for the detected objects allow us to create and test models of TNO size and orbital distributions. We test these models using a survey simulator, which simulates the detectability of model objects, accounting for the constraints and biases of our survey. Thus, we set precise constraints on the size and orbital distributions of the Neptunian Trojans, Plutinos and other resonant populations. We show that the Plutino inclination distribution is dynamically colder than found by the Canada-France Ecliptic Plane Survey. We

  10. Modeling Momentum Transfer from Kinetic Impacts: Implications for Redirecting Asteroids

    DOE PAGESBeta

    Stickle, A. M.; Atchison, J. A.; Barnouin, O. S.; Cheng, A. F.; Crawford, D. A.; Ernst, C. M.; Fletcher, Z.; Rivkin, A. S.

    2015-05-19

    Kinetic impactors are one way to deflect a potentially hazardous object headed for Earth. The Asteroid Impact and Deflection Assessment (AIDA) mission is designed to test the effectiveness of this approach and is a joint effort between NASA and ESA. The NASA-led portion is the Double Asteroid Redirect Test (DART) and is composed of a ~300-kg spacecraft designed to impact the moon of the binary system 65803 Didymos. The deflection of the moon will be measured by the ESA-led Asteroid Impact Mission (AIM) (which will characterize the moon) and from ground-based observations. Because the material properties and internal structure ofmore » the target are poorly constrained, however, analytical models and numerical simulations must be used to understand the range of potential outcomes. Here, we describe a modeling effort combining analytical models and CTH simulations to determine possible outcomes of the DART impact. We examine a wide parameter space and provide predictions for crater size, ejecta mass, and momentum transfer following the impact into the moon of the Didymos system. For impacts into “realistic” asteroid types, these models produce craters with diameters on the order of 10 m, an imparted Δv of 0.5–2 mm/s and a momentum enhancement of 1.07 to 5 for a highly porous aggregate to a fully dense rock.« less

  11. Modeling Momentum Transfer from Kinetic Impacts: Implications for Redirecting Asteroids

    SciTech Connect

    Stickle, A. M.; Atchison, J. A.; Barnouin, O. S.; Cheng, A. F.; Crawford, D. A.; Ernst, C. M.; Fletcher, Z.; Rivkin, A. S.

    2015-05-19

    Kinetic impactors are one way to deflect a potentially hazardous object headed for Earth. The Asteroid Impact and Deflection Assessment (AIDA) mission is designed to test the effectiveness of this approach and is a joint effort between NASA and ESA. The NASA-led portion is the Double Asteroid Redirect Test (DART) and is composed of a ~300-kg spacecraft designed to impact the moon of the binary system 65803 Didymos. The deflection of the moon will be measured by the ESA-led Asteroid Impact Mission (AIM) (which will characterize the moon) and from ground-based observations. Because the material properties and internal structure of the target are poorly constrained, however, analytical models and numerical simulations must be used to understand the range of potential outcomes. Here, we describe a modeling effort combining analytical models and CTH simulations to determine possible outcomes of the DART impact. We examine a wide parameter space and provide predictions for crater size, ejecta mass, and momentum transfer following the impact into the moon of the Didymos system. For impacts into “realistic” asteroid types, these models produce craters with diameters on the order of 10 m, an imparted Δv of 0.5–2 mm/s and a momentum enhancement of 1.07 to 5 for a highly porous aggregate to a fully dense rock.

  12. Asteroid Size-Frequency Distribution (The ISO Deep Asteroid Survey)

    NASA Technical Reports Server (NTRS)

    Tedesco, Edward F.

    2001-01-01

    A total of six deep exposures (using AOT CAM01 with a 6" PFOV) through the ISOCAM LW10 filter (IRAS Band 1, i.e., 12 micro-m) were obtained on an approximately 15 arcminute square field centered on the ecliptic plane. Point sources were extracted using the technique described by Desert, et al. Two known asteroids appear in these frames and 20 sources moving with velocities appropriate for main belt asteroids are present. Most of the asteroids detected have flux densities less than 1 mJy, i.e., between 150 and 350 times fainter than any of the asteroids observed by Infrared Astronomy Satellite (IRAS). These data provide the first direct measurement of the 12 micro-m sky-plane density for asteroids on the ecliptic equator. The median zodiacal foreground, as measured by ISOCAM during this survey, is found to be 22.1 +/- 1.5 mJy per pixel, i.e., 26.2 +/- 1.7 MJy/sr. The results presented here imply that the actual number of kilometer-sized asteroids is significantly greater than previously believed and in reasonable agreement with the Statistical Asteroid Model.

  13. Scientific experimentation afforded by the International Asteroid Mission

    NASA Astrophysics Data System (ADS)

    The International Asteroid Mission (IAM) affords scientists the opportunity to perform interesting and important experimentations. This opportunity is not sufficient in its own right to mandate inclusion of science into the mission. Certain scientific experimentations are essential to the success of the mission, and are the driving force behind the inclusion of science. Instrument designs incorporate the need for direct contribution to the success of the mining mission. Examples of these applications include the search for additional candidate asteroids, especially at the Earth-Sun Trojan points, with an infrared telescope facility; a gamma ray burst detector provides the crew with real-time notification of potentially harmful solar-flare activity; and a materials processing laboratory provides information on the porosity, composition, and crystalline structure of samples to optimize the mining operations in addition to yielding great insight into the history and formation of the solar-system. Instrument designs have emphasized the use of off-the-shelf hardware, demonstrated technologies. Their scientific value is derived from the location on an interplanetary platform, not necessarily advancements in technology or detection methods. Instrumentation will be delivered to the IAM project after completion of a thorough certification program. The program will include qualification, acceptance, performance, thermal balance, thermal vacuum, vibration, electromagnetic susceptibility and compatibility, and calibration testing. After delivery to the assembly-site in low-Earth orbit, an additional series of functional and compatibility tests will be required prior to initiation of the mission. The scientific instrumentation proposed for the IAM consists of experiments using a Gamma Ray Burst Detector, a Infrared Observatory, a Materials Processing Facility, Long-Wavelength Radar, Seismic Measurement Devices, Cosmic Ray Detectors, Interplanetary Plasma Measurements, a Solar

  14. Active Near Earth Asteroids

    NASA Astrophysics Data System (ADS)

    Jenniskens, Peter

    2015-08-01

    Past activity from Near Earth Asteroids is recorded in the meteoroid streams that cause our meteor showers. Automated meteoroid orbit surveys by photographic, low-light video, specular radar, and head-echo radar reflections are providing the first maps of meteor shower activity at different particle sizes. There are distinct differences in particle size distributions among streams. The underlaying mechanisms that created these streams are illuminated: fragmentation from spin-up or thermal stresses, meteoroid ejection by water vapor drag, and ejection of icy particles by CO and CO2 sublimation. The distribution of the meteoroid orbital elements probe the subsequent evolution by planetary perturbations and sample the range of dynamical processes to which Near Earth Asteroids are exposed. The non-stream "sporadic" meteors probe early stages in the evolution from meteoroid streams into the zodiacal dust cloud. We see that the lifetime of large meteoroids is generally not limited by collisions. Results obtained by the CAMS video survey of meteoroid orbits are compared to those from other orbit surveys. Since October 2010, over 200,000 meteoroid orbits have been measured. First results from an expansion into the southern hemisphere are also presented, as are first results from the measurement of main element compositions. Among the many streams detected so far, the Geminid and Sextantid showers stand out by having a relatively high particle density and derive from parent bodies that appear to have originated in the main belt.

  15. Asteroid Surface Geophysics

    NASA Astrophysics Data System (ADS)

    Murdoch, N.; Sánchez, P.; Schwartz, S. R.; Miyamoto, H.

    The regolith-covered surfaces of asteroids preserve records of geophysical processes that have occurred both at their surfaces and sometimes also in their interiors. As a result of the unique microgravity environment that these bodies possess, a complex and varied geophysics has given birth to fascinating features that we are just now beginning to understand. The processes that formed such features were first hypothesized through detailed spacecraft observations and have been further studied using theoretical, numerical, and experimental methods that often combine several scientific disciplines. These multiple approaches are now merging toward a further understanding of the geophysical states of the surfaces of asteroids. In this chapter we provide a concise summary of what the scientific community has learned so far about the surfaces of these small planetary bodies and the processes that have shaped them. We also discuss the state of the art in terms of experimental techniques and numerical simulations that are currently being used to investigate regolith processes occurring on small-body surfaces and that are contributing to the interpretation of observations and the design of future space missions.

  16. Distribution of spin axes and senses of rotation for 20 large asteroids

    NASA Astrophysics Data System (ADS)

    Magnusson, P.

    1986-10-01

    Various methods for pole determinations are examined. Previous data on the pole determination problem are reviewed. The principles and procedures of the amplitude-magnitude method which is based on a triaxial ellipsoidal model, and the epoch method which is based on the features of an observed light curves are described. It is observed that the amplitude-magnitude method provides good resolution in one-dimension and the epoch method is utilized to distinguish between prograde and retrograde senses of rotation. The data reveal that a combination of these methods is necessary to accurately predict spin axes and senses of rotation. A combination of the two methods is applied to the pole determinations for 20 main belt Trojan asteroids; the derived pole determinations are presented.

  17. Asteroids and Comets Outreach Compilation

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Contents include various different animations in the area of Asteroids and Comets. Titles of the short animated clips are: STARDUST Mission; Asteroid Castallia Impact Simulation; Castallia, Toutatis and the Earth; Simulation Asteroid Encounter with Earth; Nanorover Technology Task; Near Earth Asteroid Tracking; Champollian Anchor Tests; Early Views of Comets; Exploration of Small Bodies; Ulysses Resource Material from ESA; Ulysses Cometary Plasma Tail Animation; and various discussions on the Hale-Bopp Comet. Animation of the following are seen: the Stardust aerogel collector grid collecting cometary dust particles, comet and interstellar dust analyzer, Wiper-shield and dust flux monitor, a navigation camera, and the return of the sample to Earth; a comparison of the rotation of the Earth to the Castallia and Tautatis Asteroids; an animated land on Tautatis and the view of the motion of the sky from its surface; an Asteroid collision with the Earth; the USAF Station in Hawaii; close-up views of asteroids; automatic drilling of the Moon; exploding Cosmic Particles; and the dropping off of the plasma tail of a comet as it travels near the sun.

  18. Asteroid Size-Frequency Distribution

    NASA Technical Reports Server (NTRS)

    Tedesco, Edward F.

    2001-01-01

    A total of six deep exposures (using AOT CAM01 with a 6 inch PFOV) through the ISOCAM LW10 filter (IRAS Band 1, i.e. 12 micron) were obtained on an approximately 15 arcminute square field centered on the ecliptic plane. Point sources were extracted using the technique described. Two known asteroids appear in these frames and 20 sources moving with velocities appropriate for main belt asteroids are present. Most of the asteroids detected have flux densities less than 1 mJy, i,e., between 150 and 350 times fainter than any of the asteroids observed by IRAS. These data provide the first direct measurement of the 12 pm sky-plane density for asteroids on the ecliptic equator. The median zodiacal foreground, as measured by ISOCAM during this survey, is found to be 22.1 +/- 1.5 mJy per pixel, i.e., 26.2 +/- 1.7 MJy/sr. The results presented here imply that the actual number of kilometer-sized asteroids is significantly greater than previously believed and in reasonable agreement with the Statistical Asteroid Model.

  19. New Paradigms for Asteroid Formation

    NASA Astrophysics Data System (ADS)

    Johansen, A.; Jacquet, E.; Cuzzi, J. N.; Morbidelli, A.; Gounelle, M.

    Asteroids and meteorites provide key evidence on the formation of planetesimals in the solar system. Asteroids are traditionally thought to form in a bottom-up process by coagulation within a population of initially kilometer-scale planetesimals. However, new models challenge this idea by demonstrating that asteroids of sizes from 100 to 1000 km can form directly from the gravitational collapse of small particles that have organized themselves in dense filaments and clusters in the turbulent gas. Particles concentrate passively between eddies down to the smallest scales of the turbulent gas flow and inside large-scale pressure bumps and vortices. The streaming instability causes particles to take an active role in the concentration, by piling up in dense filaments whose friction on the gas reduces the radial drift compared to that of isolated particles. In this chapter we review new paradigms for asteroid formation and critically compare them against the observed properties of asteroids as well as constraints from meteorites. Chondrules of typical sizes from 0.1 to 1 mm are ubiquitous in primitive meteorites and likely represent the primary building blocks of asteroids. Chondrule-sized particles are nevertheless tightly coupled to the gas via friction and are therefore hard to concentrate in large amounts in the turbulent gas. We review recent progress on understanding the incorporation of chondrules into the asteroids, including layered accretion models where chondrules are accreted onto asteroids over millions of years. We highlight in the end 10 unsolved questions in asteroid formation where we expect that progress will be made over the next decade.

  20. Remote sensing of the asteroids

    NASA Technical Reports Server (NTRS)

    Chapman, C. R.

    1981-01-01

    Knowledge of the compositions of the asteroids is obtained by the remote sensing of reflected and emitted radiation from what are essentially star-like points of light. Since asteroids are a remnant population of planetesimals that were never accreted into the larger planets, their compositions and properties can provide insight into the nature of planetary matter in early epochs, before most of it was physically and chemically modified by geological processes within the planets. The progress made during the past decade in learning about asteroids through remote sensing is reviewed.

  1. Images of an Activated Asteroid

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-08-01

    In late April of this year, asteroid P/2016 G1 (PANSTARRS) was discovered streaking through space, a tail of dust extending behind it. What caused this asteroids dust activity?Asteroid or Comet?Images of asteroid P/2016 G1 at three different times: late April, late May, and mid June. The arrow in the center panel points out an asymmetric feature that can be explained if the asteroid initially ejected material in a single direction, perhaps due to an impact. [Moreno et al. 2016]Asteroid P/2016 G1 is an interesting case: though it has the orbital elements of a main-belt asteroid it orbits at just under three times the EarthSun distance, with an eccentricity of e ~ 0.21 its appearance is closer to that of a comet, with a dust tail extending 20 behind it.To better understand the nature and cause of this unusual asteroids activity, a team led by Fernando Moreno (Institute of Astrophysics of Andalusia, in Spain) performed deep observations of P/2016 G1 shortly after its discovery. The team used the 10.4-meter Great Canary Telescope to image the asteroid over the span of roughly a month and a half.A Closer Look at P/2016 G1P/2016 G1 lies in the inner region of the main asteroid belt, so it is unlikely to have any ices that suddenly sublimated, causing the outburst. Instead, Moreno and collaborators suggest that the asteroids tail may have been caused by an impact that disrupted the parent body.To test this idea, the team used computer simulations to model their observations of P/2016 G1s dust tail. Based on their models, they demonstrate that the asteroid was likely activated on February 10 2016 roughly 350 days before it reached perihelion in its orbit and its activity was a short-duration event, lasting only ~24 days. The teams models indicate that over these 24 days, the asteroid lost around 20 million kilograms of dust, and at its maximum activity level, it was ejecting around 8 kg/s!Comparison of the observation from late May (panel a) and two models: one in which

  2. Asteroid family ages

    NASA Astrophysics Data System (ADS)

    Spoto, Federica; Milani, Andrea; Knežević, Zoran

    2015-09-01

    A new family classification, based on a catalog of proper elements with ∼384,000 numbered asteroids and on new methods is available. For the 45 dynamical families with >250 members identified in this classification, we present an attempt to obtain statistically significant ages: we succeeded in computing ages for 37 collisional families. We used a rigorous method, including a least squares fit of the two sides of a V-shape plot in the proper semimajor axis, inverse diameter plane to determine the corresponding slopes, an advanced error model for the uncertainties of asteroid diameters, an iterative outlier rejection scheme and quality control. The best available Yarkovsky measurement was used to estimate a calibration of the Yarkovsky effect for each family. The results are presented separately for the families originated in fragmentation or cratering events, for the young, compact families and for the truncated, one-sided families. For all the computed ages the corresponding uncertainties are provided, and the results are discussed and compared with the literature. The ages of several families have been estimated for the first time, in other cases the accuracy has been improved. We have been quite successful in computing ages for old families, we have significant results for both young and ancient, while we have little, if any, evidence for primordial families. We found 2 cases where two separate dynamical families form together a single V-shape with compatible slopes, thus indicating a single collisional event. We have also found 3 examples of dynamical families containing multiple collisional families, plus a dubious case: for these we have obtained discordant slopes for the two sides of the V-shape, resulting in distinct ages. We have found 2 cases of families containing a conspicuous subfamily, such that it is possible to measure the slope of a distinct V-shape, thus the age of the secondary collision. We also provide data on the central gaps appearing in

  3. Structural Stability of Asteroids

    NASA Astrophysics Data System (ADS)

    Hirabayashi, Toshi

    This thesis develops a technique for analyzing the internal structure of an irregularly shaped asteroid. This research focuses on asteroid (216) Kleopatra, a few-hundred-kilometer-sized main belt asteroid spinning about its maximum moment of inertia axis with a rotation period of 5.385 hours, to motivate the techniques. While Ostro et al. [117] reported its dog bone-like shape, estimation of its size has been actively discussed. There are at least three different size estimates: Ostro et al., Descamps et al., and Marchis et al. Descamps et al. reported that (216) Kleopatra has satellites and obtained the mass of this object. This research consists of determination of possible failure modes of (216) Kleopatra and its subsequent detailed stress analysis, with each part including an estimation of the internal structure. The first part of this thesis considers the failure mode of Kleopatra and evaluates the size from it. Possible failure modes are modeled as either material shedding from the surface or plastic failure of the internal structure. The surface shedding condition is met when a zero-velocity curve with the same energy level as one of the dynamical equilibrium points attaches to the surface at the slowest spin period, while the plastic failure condition is characterized by extending the theorem by Holsapple (2008) that the yield condition of the averaged stress over the whole volume is identical to an upper bound for global failure. The prime result shows that while surface shedding does not occur at the current spin period and thus cannot result in the formation of the satellites, the neck may be situated near its plastic deformation state. From the failure condition, we also find that the size estimated by Descamps et al. (2011) is the most structurally stable. The second part of this thesis discusses finite element analyses with an assumption of an elastic-perfectly plastic material and a non-associated flow rule. The yield condition is modeled as the

  4. Asteroid Rescue Mission

    NASA Astrophysics Data System (ADS)

    Izon, S.; Kokan, T.; Lee, S.; Miller, J.; Morrell, R.; Richie, D.; Rohrschneider, R.; Rostan, S.; Staton, E.; Olds, J.

    2001-01-01

    This paper is in response to a request for papers from the Lunar and Planetary Institute in Houston, Texas as part of a National University Competition. A human rescue mission to the asteroid 16 Psyche was designed based around a failed Mars mission scenario. The scenario assumed the second human Mars mission, based on the Mars Design Reference Mission 3.0, failed to propulsively capture into Mars orbit, resulting in a higher energy trajectory headed towards the asteroid belt on an intercept trajectory with 16 Psyche. The task was to design a mission that could rescue the astronauts using existing Mars mission hardware prior to the failure of their life support system. Analysis tools were created in the following six disciplines for the design of the mission: trajectory, propulsion, habitat and life support, space rescue vehicle and earth reentry vehicle, space transfer vehicle, and operations. The disciplinary analysis tools were integrated into a computational framework in order to aid the design process. The problem was solved using a traditional fixed-point iteration method with user controlled design variables. Additionally, two other methods of optimization were implemented: design of experiments and collaborative optimization. These were looked at in order to evaluate their ease of implementation and use at solving a complex, multidisciplinary problem. The design of experiments methodology was used to create a central composite design array and a non-linear response surface equation. The response surface equation allows rapid system level optimization. Collaborative optimization is a true multidisciplinary optimization technique which benefits from disciplinary level optimization in conjunction with system level optimization. By reformatting the objective functions of the disciplinary optimizers, collaborative optimization guides the discipline optimizers toward the system optimum.

  5. Asteroids to Quasars

    NASA Astrophysics Data System (ADS)

    Lugger, Phyllis M.

    2004-12-01

    Asteroid dedication; William Liller: Biographical Sketch; William Liller: Autobiographical Meanderings; Preface; List of Participants; Conference Photo; Part I. 1. Solar System Astronomy: Asteroids Joseph Veverka; 2. Sixteen years of stellar occultations James Elliott; 3. Comets to Quasars: Surface photometry from standard stars and the morphology of the galaxy-quasar interface Peter Usher; 4. Observing Solar Eclipses Jay Pasachoff; Part II. 5. Planetary Nebulae: new insights and opportunities Lawrence Aller; 6. Studies of planetary nebulae at radio wavelengths Yervant Terzian; 7. Optical identifications of compact galactic X-ray sources: Liller Lore Jonathan Grindlay; 8. Ages of globular clusters derived from BVRI CCD photometry Gonzalo Alcaino; 9. Stellar spectrum synthesis Jun Jugaku; 10. Mass exchange and stellar abundance anomalies Benjamin Peery; Part III. Extragalactic Astronomy: 11. The M31 globular cluster system John Huchra; 12. Spiral structure and star formation in galaxies Debra Elmegreen; 13. The discovery of hot coronae around early type galaxies William Forman and Christine Jones; 14. The morphology of clusters of galaxies, the formation efficiency of galaxies and the origin of the intracluster medium Christine Jones and William Forman; 15. Testing models for the dynamical evolution of clusters of galaxies Phyllis Lugger; 16. What is in the X-ray sky? Rudolph Schild; 17. Einstein deep surveys Stephen Murray, Christine Jones and William Forman; Part IV. History, Lore and Archaeoastronomy: 18. Robert Wheeler Willson: His Life and Legacy Barbara Welther; 19. The great mnemonics contest Owen Gingerich; 20. Hetu'u Rapanui: The archaeoastronomy of Easter Island William Liller; Indexes; Names; Objects; Subjects.

  6. Solar wind tans young asteroids

    NASA Astrophysics Data System (ADS)

    2009-04-01

    A new study published in Nature this week reveals that asteroid surfaces age and redden much faster than previously thought -- in less than a million years, the blink of an eye for an asteroid. This study has finally confirmed that the solar wind is the most likely cause of very rapid space weathering in asteroids. This fundamental result will help astronomers relate the appearance of an asteroid to its actual history and identify any after effects of a catastrophic impact with another asteroid. ESO PR Photo 16a/09 Young Asteroids Look Old "Asteroids seem to get a ‘sun tan' very quickly," says lead author Pierre Vernazza. "But not, as for people, from an overdose of the Sun's ultraviolet radiation, but from the effects of its powerful wind." It has long been known that asteroid surfaces alter in appearance with time -- the observed asteroids are much redder than the interior of meteorites found on Earth [1] -- but the actual processes of this "space weathering" and the timescales involved were controversial. Thanks to observations of different families of asteroids [2] using ESO's New Technology Telescope at La Silla and the Very Large Telescope at Paranal, as well as telescopes in Spain and Hawaii, Vernazza's team have now solved the puzzle. When two asteroids collide, they create a family of fragments with "fresh" surfaces. The astronomers found that these newly exposed surfaces are quickly altered and change colour in less than a million years -- a very short time compared to the age of the Solar System. "The charged, fast moving particles in the solar wind damage the asteroid's surface at an amazing rate [3]", says Vernazza. Unlike human skin, which is damaged and aged by repeated overexposure to sunlight, it is, perhaps rather surprisingly, the first moments of exposure (on the timescale considered) -- the first million years -- that causes most of the aging in asteroids. By studying different families of asteroids, the team has also shown that an asteroid

  7. Planet-crossing asteroid survey

    NASA Technical Reports Server (NTRS)

    Atallah, C. A.

    1982-01-01

    Ephemerides computed from asteroid orbits and the 48 in. Palomar Schmidt log book were used to determine the number of objects that might have appeared in photographic plates taken in years other than 1979. Thus, new positions would be calculated aiding the refinement of the preliminary orbits of these asteroids, eventually leading to their permanent number of designation. From these 109 asteroids, 35 were potentially on 97 plates taken at Palomar between 1976 and 1981. Unfortunately, only 27 plates were readily available and the number of tentative asteroids was reduced to 10. Upon examination of the film, only six objects were found to be in the region predicted by their ephemerides. The position of these objects was measured to the one arcsecond precision.

  8. Asteroid Lightcurves from Estcorn Observatory

    NASA Astrophysics Data System (ADS)

    Klinglesmith, Daniel A., III; Hendrickx, Sebastian; Madden, Karl; Montgomery, Samuel

    2016-07-01

    We obtained lightcurves and amplitudes for 17 asteroids, 8 of which had unknown or poorly determined periods. The other 9 have known lightcurves at several oppositions and so are candidates for spin/shape analysis.

  9. Camping Out On An Asteroid

    NASA Video Gallery

    An astronaut and a geologist recently spent three days camping out as though they were on an asteroid. They were inside NASA's Space Exploration Vehicle prototype, flying it virtually in a digital ...

  10. Asteroid 433 Eros Approaches Earth

    NASA Video Gallery

    Asteroid 433 Eros made a close approach to Earth the morning of January 31st coming within 0.17 AU (15 million miles) of our planet. In this set of images taken that morning, the bright moving dot ...

  11. Asteroids: Dark and stormy weather

    NASA Astrophysics Data System (ADS)

    Clark, Beth Ellen

    2012-11-01

    Can some of the ageing effects on asteroid surfaces be caused by an interplanetary rain of carbon-rich Solar System debris? Observations from the Dawn space mission suggest that the answer is yes. See Letters p.79 & p.83

  12. Near-Earth Asteroid Returned Sample (NEARS)

    NASA Technical Reports Server (NTRS)

    Shoemaker, Eugene M.; Cheng, Andrew F.

    1994-01-01

    The concept of the Near-Earth Asteroid Returned Sample (NEARS) mission is to return to Earth 10-100 g from each of four to six sites on a near-Earth asteroid and to perform global characterization of the asteroid and measure mass, volume, and density to ten percent. The target asteroid for the mission is 4660 Nereus, probably a primitive C-type asteroid, with the alternate target being 1989ML, an extremely accessible asteroid of unknown type. Launch dates will be 1998, 2000, 2002, and 2004 on the Delta II-7925 launch vehicle. The mission objectives are three-fold. (1) Provide first direct and detailed petrological, chemical, age, and isotopic characterization of a near-Earth asteroid and relate it to terrestrial, lunar, and meteoritic materials. (2) Sample the asteroid regolith and characterize any exotic fragments. (3) Identify heterogeneity in the asteroid's isotopic properties, age, and elemental chemistry.

  13. Asteroid Ida and Its Moon

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This is the first full picture showing both asteroid 243 Ida and its newly discovered moon to be transmitted to Earth from the National Aeronautics and Space Administration's (NASA's) Galileo spacecraft--the first conclusive evidence that natural satellites of asteroids exist. Ida, the large object, is about 56 kilometers (35 miles) long. Ida's natural satellite is the small object to the right. This portrait was taken by Galileo's charge-coupled device (CCD) camera on August 28, 1993, about 14 minutes before the Jupiter-bound spacecraft's closest approach to the asteroid, from a range of 10,870 kilometers (6,755 miles). Ida is a heavily cratered, irregularly shaped asteroid in the main asteroid belt between Mars and Jupiter--the 243rd asteroid to be discovered since the first was found at the beginning of the 19th century. Ida is a member of a group of asteroids called the Koronis family. The small satellite, which is about 1.5 kilometers (1 mile) across in this view, has yet to be given a name by astronomers. It has been provisionally designated '1993 (243) 1' by the International Astronomical Union. ('1993' denotes the year the picture was taken, '243' the asteroid number and '1' the fact that it is the first moon of Ida to be found.) Although appearing to be 'next' to Ida, the satellite is actually in the foreground, slightly closer to the spacecraft than Ida is. Combining this image with data from Galileo's near-infrared mapping spectrometer, the science team estimates that the satellite is about 100 kilometers (60 miles) away from the center of Ida. This image, which was taken through a green filter, is one of a six-frame series using different color filters. The spatial resolution in this image is about 100 meters (330 feet) per pixel.

  14. 4. TROJAN MILL, DETAIL OF CRUDE ORE BINS FROM NORTH, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. TROJAN MILL, DETAIL OF CRUDE ORE BINS FROM NORTH, c. 1912. SHOWS TIMBER FRAMING UNDER CONSTRUCTION FOR EAST AND WEST CRUDE ORE BINS AT PREVIOUS LOCATION OF CRUSHER HOUSE, AND SNOW SHED PRESENT OVER SOUTH CRUDE ORE BIN WITH PHASE CHANGE IN SNOW SHED CONSTRUCTION INDICATED AT EAST END OF EAST CRUDE ORE BIN. THIS PHOTOGRAPH IS THE FIRST IMAGE OF THE MACHINE SHOP, UPPER LEFT CORNER. CREDIT JW. - Bald Mountain Gold Mill, Nevada Gulch at head of False Bottom Creek, Lead, Lawrence County, SD

  15. 7. TROJAN MILL, EXTERIOR FROM NORTHWEST, c. 191828. ADDITIONS FOR ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. TROJAN MILL, EXTERIOR FROM NORTHWEST, c. 1918-28. ADDITIONS FOR PRIMARY THICKENERS No. 1 AND No. 2, SECONDARY THICKENERS No. 1, No. 2, AND No. 3, AGITATORS, AIR COMPRESSOR, AND PORTLAND FILTERS ARE SHOWN COMPLETE. STAIR ON NORTH SIDE OF CRUDE ORE BINS IS PRESENT AS IS THE LIME BIN ADJACENT TO THE WEST CRUDE ORE BIN, AND THE SNOW SHED ADDED OVER THE TRAMLINE SERVING THE EAST AND WEST CRUDE ORE BINS. ALSO PRESENT IS THE BABBITT HOUSE AND ROCK BIN. CREDIT JW. - Bald Mountain Gold Mill, Nevada Gulch at head of False Bottom Creek, Lead, Lawrence County, SD

  16. A hitchhiker’s guide to the Trojan Horse Method

    NASA Astrophysics Data System (ADS)

    Pizzone, R. G.; Spitaleri, C.; Cherubini, S.; D'Agata, G.; Guardo, G. L.; Gulino, M.; La Cognata, M.; Lamia, L.; Puglia, S. M. R.; Rapisarda, G. G.; Romano, S.; Sergi, M. L.; Spartá, R.; Tumino, A.

    2016-04-01

    Owing the presence of the Coulomb barrier at astrophysically relevant kinetic energies, it is very difficult, or sometimes impossible to measure astrophysical reaction rates in laboratory. This is why different indirect techniques are being used along with direct measurements. The THM is unique indirect technique allowing one measure astrophysical rearrangement reactions down to astrophysical relevant energies. The basic principle and a review of the main application of the Trojan Horse Method are presented. A step-by-step approach will be adopted in order to describe the features usually unknown to non-experts.

  17. Modelling asteroid spectra: few examples

    NASA Astrophysics Data System (ADS)

    Birlan, M.; Popescu, M.

    2011-10-01

    Asteroidal population comprises now more than 500,000 objects. Several observational techniques (spectroscopy, adaptive optics, photometry, polarimetry, radar,..) are used in order to obtain a mature understanding of an overall knowledge of this population. Spectroscopy can play a key role in determining the chemical composition and physical process that took place and modified the surface of asteroids. The development of telescopic instruments and the possibility to access them remotely allowed an increasing number of asteroid spectral measurements. The exploitation of spectral measurements is one of the important items to enlarge our science of surfaces of atmosphereless bodies. Spectral data of asteroids are in continuing growth. To exploit these spectral data we must account the global science of this population as well as the knowledge derived by studies of comparative planetology. The project M4AST (Modeling for Asteroids) consists in a database containing the results of these telescopic measurements and a set of applications for spectral analysis (Fig. 1). M4AST cover several aspects related to statistics of asteroids (taxonomy), mineralogical solutions using laboratory spectra from RELAB, and mineralogical modeling using space weathering effects corroborated with radiative transfer laws. M4AST was conceived to be available via a web interface and will be available for the scientific community. The abilities of these routines will be highlighted by few examples. Science derived via M4AST obtained for (222) Lucia, (809) Lundia, (810) Atossa, (1005) Arago, (1220) Crocus, and (4486) Mithra will be presented.

  18. Lightcurve Analysis of the Hungaria Binary 7958 Leakey

    NASA Astrophysics Data System (ADS)

    Stephens, Robert D.; Warner, Brian D.; Marchini, Alessandro; Salvaggio, Fabio; Papini, Riccardo

    2016-04-01

    The Hungaria asteroid 7958 Leakey is a known binary (Warner et al., 2012). It was observed in 2015 to confirm and refine the original periods for the primary rotation and satellite orbit. The analysis of the 2015 data found a noticeably different orbital period. We report on the analysis of the new data and a second look at the data from 2012.

  19. Future Small Body Exploration after the Investigation of Asteroid Itokawa by Remote Sensing and Returned Sample Analyses

    NASA Astrophysics Data System (ADS)

    Yano, Hajime

    2015-03-01

    the endeavor. JAXAfs solar power sail mission aims for eventual rendezvous with Jovian Trojan asteroids, reservoir of D/P-type asteroids as either leftovers of Jupiter system formation or the second generation intruders from the Kuiper belt regions.

  20. Simulation of the dusty plasma environment of 65803 Didymos for the Asteroid Impact Mission (AIM)

    NASA Astrophysics Data System (ADS)

    Cipriani, Fabrice; Rodgers, David; Hilgers, Alain; Hess, Sebastien; Carnelli, Ian

    2016-10-01

    The Asteroid Impact and Deflection Assessment mission (AIDA) is a joint European-US technology demonstrator mission including the DART asteroid impactor (NASA/JHU/APL) and the AIM asteroid rendezvous platform (ESA/DLR/OCA) set to reach Near Earth binary Object 65803 Didymos in October 2022. Besides technology demonstration in the deep space communications domain and the realization of a kinetic impact on the moonlet to study deflection parameters, this asteroid rendezvous mission is an opportunity to carry out in-situ observations of the close environment of a binary system, addressing some fundamental science questions. The MASCOT-2 lander will be released from the AIM platform and operate at the surface of the moonlet of 65803 Didymos, complemented by the ability of the Cubesat Opportunity Payloads (COPINS) to sample the close environment of the binary.In this context, we have developed an model describing the plasma and charged dust components of the near surface environment of the moonlet (170m in diameter), targeted by the MASCOT-2 lander and of the DART impactor. We performed numerical simulations in order to estimate the electrostatic surface potentials at various locations of the surface, resulting from its interaction with the solar wind plasma and solar photons. In addition, we describe charging levels, density profiles, and velocity distribution of regolith grains lifted out from the surface up to about 70m above the surface.

  1. Sizes, Shapes, and Satellites of Asteroids from Occultations

    NASA Astrophysics Data System (ADS)

    Waring Dunham, David; Herald, David Russell; Preston, Steve; Timerson, Bradley; Maley, Paul; Frappa, Eric; Hayamizu, Tsutomu; Talbot, John; Poro, Atila

    2015-08-01

    For 40 years, the sizes and shapes of dozens of asteroids have been determined from observations of asteroidal occultations. Some of the first evidence for satellites of asteroids was obtained from the early efforts; now, the orbits and sizes of some satellites discovered by other means have been refined from occultation observations. Also, several close binary stars have been discovered, and the angular diameters of some stars have been measured from analysis of these observations. The International Occultation Timing Association (IOTA) coordinates this activity worldwide, from predicting and publicizing the events, to accurately timing the occultations from as many stations as possible, and publishing and archiving the observations.The release of the Hipparcos and Tycho catalogs in 1997, from ESA’s Hipparcos space mission, revolutionized asteroidal occultation work, increasing the routine accuracy of the predictions and the annual number of observations by an order of magnitude. IOTA developed an efficient procedure for predicting the occultations using a combination of new star catalogs, based on Hipparcos and new star catalogs, generated mainly at the U. S. Naval Observatory (USNO), and new observations of asteroids relative to the improved astrometric nets mainly from USNO’s Flagstaff Astrometric Scanning Transit Telescope and JPL’s Table Mountain Observatory. In addition, many IOTA observers now use inexpensive low-light-level video cameras and specially built GPS video time inserters to accurately time the events. This automation has also allowed some observers to deploy multiple remote video stations across occultation paths. Then, one observer can record several “chords” across the asteroid. The cameras are sensitive enough that easily-hidden telescopes, many of which can be packed in standard air travel suitcases, can be used for many of the predicted occultations. IOTA’s network of regional coordinators collect and reduce the observations

  2. Lightcurve Analysis of the Hungaria Asteroid 30935 Davasobel

    NASA Astrophysics Data System (ADS)

    Benishek, Vladimir; Warner, Brian D.

    2015-07-01

    After a single night of observations at the Sopot Astronomical Observatory on 2014 Dec 31, there were possible indications of an attenuation that would indicate that the asteroid was binary. A collaboration was formed by the authors to obtain data from well-separated locations in case the potential satellite had an orbital period commensurate with an Earth day. The final data set contained no significant secondary period and led to a single period solution of P = 3.9769 ± 0.0005 h, A = 0.60 ± 0.03 mag.

  3. Binary stars.

    PubMed

    Paczynacuteski, B

    1984-07-20

    Most stars in the solar neighborhood are either double or multiple systems. They provide a unique opportunity to measure stellar masses and radii and to study many interesting and important phenomena. The best candidates for black holes are compact massive components of two x-ray binaries: Cygnus X-1 and LMC X-3. The binary radio pulsar PSR 1913 + 16 provides the best available evidence for gravitational radiation. Accretion disks and jets observed in close binaries offer a very good testing ground for models of active galactic nuclei and quasars.

  4. Binary stars.

    PubMed

    Paczynacuteski, B

    1984-07-20

    Most stars in the solar neighborhood are either double or multiple systems. They provide a unique opportunity to measure stellar masses and radii and to study many interesting and important phenomena. The best candidates for black holes are compact massive components of two x-ray binaries: Cygnus X-1 and LMC X-3. The binary radio pulsar PSR 1913 + 16 provides the best available evidence for gravitational radiation. Accretion disks and jets observed in close binaries offer a very good testing ground for models of active galactic nuclei and quasars. PMID:17749544

  5. Asteroid Exploration and Exploitation

    NASA Technical Reports Server (NTRS)

    Lewis, John S.

    2006-01-01

    John S. Lewis is Professor of Planetary Sciences and Co-Director of the Space Engineering Research Center at the University of Arizona. He was previously a Professor of Planetary Sciences at MIT and Visiting Professor at the California Institute of Technology. Most recently, he was a Visiting Professor at Tsinghua University in Beijing for the 2005-2006 academic year. His research interests are related to the application of chemistry to astronomical problems, including the origin of the Solar System, the evolution of planetary atmospheres, the origin of organic matter in planetary environments, the chemical structure and history of icy satellites, the hazards of comet and asteroid bombardment of Earth, and the extraction, processing, and use of the energy and material resources of nearby space. He has served as member or Chairman of a wide variety of NASA and NAS advisory committees and review panels. He has written 17 books, including undergraduate and graduate level texts and popular science books, and has authored over 150 scientific publications.

  6. WISE Finds Fewer Asteroids near Earth

    NASA Video Gallery

    New observations by NASA's Wide-field Infrared Survey Explorer, orWISE, show there are significantly fewer near-Earth asteroids in themid-size range than previously thought.› Asteroid and Come...

  7. Asteroid Redirect Mission: Boulder Collection Concept

    NASA Video Gallery

    This animation illustrates one of two robotic mission concepts under consideration for NASA's Asteroid Redirect Mission. In this concept, the Asteroid Redirect Vehicle descends to the surface of a ...

  8. Asteroid Redirect Mission: EVA and Sample Collection

    NASA Technical Reports Server (NTRS)

    Abell, Paul; Stich, Steve

    2015-01-01

    Asteroid Redirect Mission (ARM) Overview (1) Notional Development Schedule, (2) ARV Crewed Mission Accommodations; Asteroid Redirect Crewed Mission (ARCM) Mission Summary; ARCM Accomplishments; Sample collection/curation plan (1) CAPTEM Requirements; SBAG Engagement Plan

  9. Unveiling Clues from Spacecraft Missions to Comets and Asteroids through Impact Experiments

    NASA Technical Reports Server (NTRS)

    Lederer, Susan M.; Jensen, Elizabeth; Fane, Michael; Smith, Douglas; Holmes, Jacob; Keller, Lindasy P.; Lindsay, Sean S.; Wooden, Diane H.; Whizin, Akbar; Cintala, Mark J.; Zolensky, Michael

    2016-01-01

    The Deep Impact Spacecraft mission was the first to boldly face the challenge of impacting the surface of a comet, 9P/Tempel 1, to investigate surface and subsurface 'pristine' materials. The Stardust mission to Comet 81P/Wild 2 brought back an exciting surprise: shocked minerals which were likely altered during the comet's lifetime. Signatures of shock in meteorites also suggest that the violent past of the solar system has left our small bodies with signatures of impacts and collisions. These results have led to the question: How have impacts affected the evolutionary path taken by comets and asteroids, and what signatures can be observed? A future planetary mission to a near-Earth asteroid is proposing to take the next steps toward understanding small bodies through impacts. The mission would combine an ESA led AIM (Asteroid Impact Mission) with a JHU/APL led DART (Double Asteroid Redirect Mission) spacecraft to rendezvous with binary near-Earth asteroid 65803 Didymus (1996 G2). DART would impact the smaller asteroid, 'Didymoon' while AIM would characterize the impact and the larger Didymus asteroid. With these missions in mind, a suite of experiments have been conducted at the Experimental Impact Laboratory (EIL) at NASA Johnson Space Center to investigate the effects that collisions may have on comets and asteroids. With the new capability of the vertical gun to cool targets in the chamber through the use of a cold jacket fed by liquid nitrogen, the effects of target temperature have been the focus of recent studies. Mg-rich forsterite and enstatite (orthopyroxene), diopside (monoclinic pyroxene) and magnesite (Mg-rich carbonate) were impacted. Target temperatures ranged from 25 deg to -100 deg, monitored by connecting thermocouples to the target container. Impacted targets were analyzed with a Fourier Transform Infrared Spectrometer (FTIR) and Transmission Electron Microscope (TEM). Here we present the evidence for impact-induced shock in the minerals through

  10. Excluding interlopers from asteroid families

    NASA Astrophysics Data System (ADS)

    Novakovic, B.; Radovic, V.

    2014-07-01

    Introduction: Asteroid families are believed to have originated from catastrophic collisions among asteroids. They are a very important subject of Solar System investigation, because practically any research topic carried out in asteroid-related science sooner or later encounters problems pertaining to asteroid families. One basic problem encountered when dealing with families is to determine reliably the list of its members, i.e. to reduce the number of interlopers as much as possible. This is an important problem, because many conclusions derived from analyses of the physical properties of family members must be necessarily based on firm and well established membership. However, as the number of known asteroids increases fast it becomes more and more difficult to obtain robust list of members of an asteroid family. To cope with these challenges we are proposing a new approach that may help to significantly reduce presence of interlopers among the family members. This method should be particularly useful once additional information become available, including primarily spectro-photometric data. This is exactly the kind of information that will be provided by Gaia. Metodology: Families (and their members) have been commonly identified by analysing the distribution of asteroids in the space of proper orbital elements, using the Hierarchical Clustering Method (HCM) [1]. A well-known drawback of the HCM based on the single linkage rule is the so-called chaining phenomenon: first concentrations naturally tend to incorporate nearby groups, forming a kind of 'chain'. Thus, any family membership obtained by the pure HCM must unavoidably include some interlopers. The method we are proposing here could be used to identify these interlopers, with its main advantage being an ability to significantly reduce the chaining effect. The method consists of three main steps. First we determine an asteroid family members by applying the HCM to the catalogue of proper elements obtained

  11. Asteroid shape modelling with ADAM

    NASA Astrophysics Data System (ADS)

    Viikinkoski, Matti; Kaasalainen, Mikko; Durech, Josef

    2015-08-01

    Technological advancements have made it possible to obtain highly detailed images of asteroids, yet 3-D shape reconstruction remains a challenge. Shape inversion is an ill-posed inverse problem as systematic errors, shadowing effects due to non-convex features, and the limitations of the imaging systems render the direct inversion impossible. Moreover, the coverage of one observation session alone is seldom sufficient for 3-D reconstruction, necessitating a method for the integration of widely different, complementary data sources into a coherent shape solution.We present a new 3-D shape reconstruction method for asteroid models. ADAM, an acronym for all-data asteroid modelling, is a general procedure for combining disk-resolved observational data into a shape model. ADAM handles all disk-resolved data in a uniform manner via 2-D Fourier Transform. Almost all disk-resolved data sources are supported: adaptive optics and other images, range-Doppler radar data, and thermal infrared interferometry.As case studies, we examine the shape of (41) Daphne using the adaptive optics images and photometry, and create a model of the asteroid 2000 ET70 from the range-Doppler radar images. Finally, we combine ALMA science verification data, adaptive optics images, occultations, and lightcurve data to study the shape of the large main-belt asteroid (3) Juno.

  12. Asteroid airburst altitude vs. strength

    NASA Astrophysics Data System (ADS)

    Robertson, Darrel; Wheeler, Lorien; Mathias, Donovan

    2016-10-01

    Small NEO asteroids (<Ø140m) may not be a threat on a national or global level but can still cause a significant amount of local damage as demonstrated by the Chelyabinsk event where there was over $33 million worth of damage (1 billion roubles) and 1500 were injured, mostly due to broken glass. The ground damage from a small asteroid depends strongly on the altitude at which they "burst" where most of the energy is deposited in the atmosphere. The ability to accurately predict ground damage is useful in determining appropriate evacuation or shelter plans and emergency management.Strong asteroids, such as a monolithic boulder, fail and create peak energy deposition close to the altitude at which ram dynamic pressure exceeds the material cohesive strength. Weaker asteroids, such as a rubble pile, structurally fail at higher altitude, but it requires the increased aerodynamic pressure at lower altitude to disrupt and disperse the rubble. Consequently the resulting airbursts have a peak energy deposition at similar altitudes.In this study hydrocode simulations of the entry and break-up of small asteroids were performed to examine the effect of strength, size, composition, entry angle, and speed on the resulting airburst. This presentation will show movies of the simulations, the results of peak burst height, and the comparison to semi-analytical models.

  13. The compositional distribution of asteroids

    NASA Astrophysics Data System (ADS)

    DeMeo, F.; Carry, B.; Alexander, C.; Walsh, K.; Chapman, C.

    2014-07-01

    Each compositional class of asteroid is a relic of the temperature and composition conditions in which it formed. The current distribution reveals the history of the Solar System, and each body acts as a marker of any mixing that occurred since formation. The remnant of a primordial temperature gradient, seen as transition from the S class to C class dominating in different regions of the asteroid belt has been a paradigm for three decades [1-4]. Today, we are armed with major advancements from the past decade that have revolutionized the field of asteroids in areas such as discovery, physical characterization, and dynamical models. A new and more detailed compositional map [5,6] created with data from the Sloan Digital Sky Survey [7] allows us to re-examine compositional trends in the main asteroid belt and what the physical and dynamical implications might be. This talk is related to recent work from DeMeo & Carry 2013, 2014 [5,6] and an upcoming chapter of the "Asteroids IV" book in 2015.

  14. Accessibility of near-Earth asteroids, 1990

    NASA Technical Reports Server (NTRS)

    Hulkower, Neal D.; Child, Jack B.

    1991-01-01

    Previous research which analyzed the accessibility of all known near-Earth asteroids is updated. Since then, many new near-Earth asteroids have been discovered, and 1928 DB, the most accessible asteroid at that time, has been recovered. Many of these recently discovered near-Earth asteroids have promising orbital characteristics. In addition to accessibility (as defined by minimum global delta v), ideal rendezvous opportunities are identified.

  15. Rotational properties of small asteroids: Photoelectric observations of 16 asteroids

    NASA Astrophysics Data System (ADS)

    Barucci, M. A.; di Martino, M.; Dotto, E.; Fulchignoni, M.; Rotundi, A.; Burchi, R.

    1994-06-01

    Continuing the observational program started in 1984 on small asteroids (diameter smaller than bout 50 km), we present the results of photometric observations performed with a 1-m telescope at the European Southern Observatory (ESO). A total of 56 single-night lightcurves for 16 asteroids were obtained. All the objects were observed for the first time and the rotational periods have been determined for 11. For 655 Briseis, 823 Sisigambis, 847 Agnia, 1591 Baize, and 3237 Victorplatt the complete rotational phase was not covered and in some cases only an indication of the rotational period has been possible.

  16. The spherical Brazil Nut Effect and its significance to asteroids

    NASA Astrophysics Data System (ADS)

    Perera, Viranga; Jackson, Alan P.; Asphaug, Erik; Ballouz, Ronald-Louis

    2016-11-01

    Many asteroids are likely rubble-piles that are a collection of smaller objects held together by gravity and possibly cohesion. These asteroids are seismically shaken by impacts, which leads to excitation of their constituent particles. As a result it has been suggested that their surfaces and sub-surface interiors may be governed by a size sorting mechanism known as the Brazil Nut Effect. We study the behavior of a model asteroid that is a spherical, self-gravitating aggregate with a binary size-distribution of particles under the action of applied seismic shaking. We find that above a seismic threshold, larger particles rise to the surface when friction is present, in agreement with previous studies that focussed on cylindrical and rectangular box configurations. Unlike previous works we also find that size sorting takes place even with zero friction, though the presence of friction does aid the sorting process above the seismic threshold. Additionally we find that while strong size sorting can take place near the surface, the innermost regions remain unsorted under even the most vigorous shaking.

  17. Uncertainty maps for asteroid shape and pole solutions

    NASA Astrophysics Data System (ADS)

    Bartczak, Przemyslaw; Dudzinski, Grzegorz

    2016-10-01

    SAGE (Shaping Asteroids with Genetic Evolution) inversion method is based on genetic algorithm to obtain pole solutions, rotation periods and non-convex shapes of asteroids (Bartczak et.al, 2014). During the process computer graphics methods are used to compare model's synthetic lightcurves to photometric observations. The method is suitable for modelling both single and binary objects. A modelling run starts with a sphere, with no assumptions about the shape, and subsequently it converges to a stable spin and shape solution. Center of mas and moment of inertia are calculated for each model.Modelling of an asteroid consists of multiple runs of the process, each of them following different path towards a stable solution. As a result we obtain a family of solutions. If enough data is provided, solutions are consistent with each other and can be used for error estimation.We choose only the best models from a family of solutions, meaning every model that fits 5% threshold above best χ2 found. By comparing them we are able to construct a map of uncertainties for the shape, showing areas in good and poor agreement with chosen models. Such map can then be represented with a 3D visualisation. Moreover, we create a map of errors for pole solutions and periods.

  18. Recent Arecibo Radar Observations of Main-Belt Asteroids.

    NASA Astrophysics Data System (ADS)

    Shepard, Michael K.; Howell, Ellen; Nolan, Michael; Taylor, Patrick; Springmann, Alessondra; Giorgini, Jon; Benner, Lance; Magri, Christopher

    2014-11-01

    We recently observed main-belt asteroids 12 Victoria (Tholen S-class, Bus L-class), 246 Asporina (A-class), and 2035 Stearns with the S-band (12 cm) Arecibo radar. Signal-to-noise ratios for Asporina and Stearns were only strong enough for continuous-wave (CW) analysis. Signal-to-noise ratios for Victoria were high enough for delay-Doppler imaging. Stearns exhibited a high radar polarization ratio of unity, higher than any other main-belt E-class, but similar to near-Earth E-class asteroids [Benner et al. Icarus 198, 294-304, 2008; Shepard et al. Icarus 215, 547-551, 2011]. The A-class asteroids show spectral absorption features consistent with olivine and have been suggested as the source of pallasite meteorites or the rare brachinites [Cruikshank and Hartmann, Science 223, 281-283, 1984]. The radar cross-section measured for Asporina leads to a radar albedo estimate of 0.11, suggesting a low near-surface bulk density, and by inference, a low metal content. This suggests that the brachinites are a better analog for Asporina than the iron-rich pallasites. Victoria has been observed by radar in the past and the continuous-wave echoes suggest it has a large concavity or is a contact binary [Mitchell et al. Icarus 118, 105-131, 1995]. Our new imaging observations should determine which is more likely.

  19. Lowell Observatory Near-Earth Asteroid Photometric Survey (NEAPS) - 2009 January through 2009 June

    NASA Astrophysics Data System (ADS)

    Koehn, Bruce W.; Bowell, Edward G.; Skiff, Brian A.; Sanborn, Jason J.; McLelland, Kyle P.; Pravec, Petr; Warner, Brian D.

    2014-10-01

    We report the results of the Lowell Observatory Near- Earth Asteroid Photometric Survey (NEAPS) for the period between 2009-01-01 and 2009-06-30. During this period, we obtained our first photometric data for 40 asteroids including 433 Eros, 1943 Anteros, 3554 Amun, 5011 Ptah, (5604) 1992 FE, 5620 Jasonwheeler, (5693) 1993 EA, (8566) 1996 EN, (14402) 1991 DB, (16834) 1997 WU22, (22753) 1998 WT, (35107) 1991 VH, (52768) 1998 OR2, (68350) 2001 MK3, (85867) 1999 BY9, (138883) 2000 YL29, (141052) 2001 XR1, (143651) 2003 QO104, (154244) 2002 KL6, 161989 Cacus, (162385) 2000 BM19, (163758) 2003 OS13, (175706) 1996 FG3, (194386) 2001 VG5, (203217) 2001 FX9, (207945) 1991 JW, (208023) 1999 AQ10, (212546) 2006 SV19, (256412) 2007 BT2, 2001 FE90, 2004 LV3, 2005 BC, 2005 SG19, 2008 QT3, 2008 WL60, 2009 DE47, 2009 DO111, 2009 EP2, 2009 FD, and 2009 JM2. We also report our analysis of 5261 Eureka, a Mars Trojan.

  20. Physical Parameters of Asteroids Estimated from the WISE 3 Band Data and NEOWISE Post-Cryogenic Survey

    NASA Astrophysics Data System (ADS)

    Mainzer, A.; Grav, T.; Masiero, J.; Bauer, J.; Cutri, R.; McMillan, R.; Nugent, C. R.; Tholen, D.; Wright, E. L.

    2012-12-01

    Enhancements to the science data processing pipeline of NASA's Wide-field Infrared Explorer (WISE) mission, collectively known as NEOWISE, resulted in the detection of >158,000 minor planets in four infrared wavelengths during the fully cryogenic portion of the mission. Following the depletion of its cryogen, NASA's Planetary Science Directorate funded a four month extension to complete the survey of the inner edge of the Main Asteroid Belt and to detect and discover near-Earth objects (NEOs). This extended survey phase, known as the NEOWISE Post-Cryogenic Survey, resulted in the detection of 6500 large Main Belt asteroids and 86 NEOs in its 3.4 and 4.6 $ um channels. During the Post-Cryogenic Survey, NEOWISE discovered and detected a number of asteroids co-orbital with the Earth and Mars, including the first known Earth Trojan. We present preliminary thermal fits for these and other NEOs detected during the 3-Band Cryogenic and Post-Cryogenic Surveys.

  1. PHYSICAL PARAMETERS OF ASTEROIDS ESTIMATED FROM THE WISE 3-BAND DATA AND NEOWISE POST-CRYOGENIC SURVEY

    SciTech Connect

    Mainzer, A.; Masiero, J.; Bauer, J.; Grav, T.; Cutri, R. M.; McMillan, R. S.; Nugent, C. R.; Tholen, D.; Walker, R.; Wright, E. L.

    2012-11-20

    Enhancements to the science data processing pipeline of NASA's Wide-field Infrared Survey Explorer (WISE) mission, collectively known as NEOWISE, resulted in the detection of >158,000 minor planets in four infrared wavelengths during the fully cryogenic portion of the mission. Following the depletion of its cryogen, NASA's Planetary Science Directorate funded a four-month extension to complete the survey of the inner edge of the Main Asteroid Belt and to detect and discover near-Earth objects (NEOs). This extended survey phase, known as the NEOWISE Post-Cryogenic Survey, resulted in the detection of {approx}6500 large Main Belt asteroids and 86 NEOs in its 3.4 and 4.6 {mu}m channels. During the Post-Cryogenic Survey, NEOWISE discovered and detected a number of asteroids co-orbital with the Earth and Mars, including the first known Earth Trojan. We present preliminary thermal fits for these and other NEOs detected during the 3-Band Cryogenic and Post-Cryogenic Surveys.

  2. System-level protection and hardware Trojan detection using weighted voting☆

    PubMed Central

    Amin, Hany A.M.; Alkabani, Yousra; Selim, Gamal M.I.

    2013-01-01

    The problem of hardware Trojans is becoming more serious especially with the widespread of fabless design houses and design reuse. Hardware Trojans can be embedded on chip during manufacturing or in third party intellectual property cores (IPs) during the design process. Recent research is performed to detect Trojans embedded at manufacturing time by comparing the suspected chip with a golden chip that is fully trusted. However, Trojan detection in third party IP cores is more challenging than other logic modules especially that there is no golden chip. This paper proposes a new methodology to detect/prevent hardware Trojans in third party IP cores. The method works by gradually building trust in suspected IP cores by comparing the outputs of different untrusted implementations of the same IP core. Simulation results show that our method achieves higher probability of Trojan detection over a naive implementation of simple voting on the output of different IP cores. In addition, experimental results show that the proposed method requires less hardware overhead when compared with a simple voting technique achieving the same degree of security. PMID:25685518

  3. The differing magnitude distributions of the two Jupiter Trojan color populations

    SciTech Connect

    Wong, Ian; Brown, Michael E.; Emery, Joshua P.

    2014-12-01

    The Jupiter Trojans are a significant population of minor bodies in the middle solar system that have garnered substantial interest in recent years. Several spectroscopic studies of these objects have revealed notable bimodalities with respect to near-infrared spectra, infrared albedo, and color, which suggest the existence of two distinct groups among the Trojan population. In this paper, we analyze the magnitude distributions of these two groups, which we refer to as the red and less red color populations. By compiling spectral and photometric data from several previous works, we show that the observed bimodalities are self-consistent and categorize 221 of the 842 Trojans with absolute magnitudes in the range H<12.3 into the two color populations. We demonstrate that the magnitude distributions of the two color populations are distinct to a high confidence level (>95%) and fit them individually to a broken power law, with special attention given to evaluating and correcting for incompleteness in the Trojan catalog as well as incompleteness in our categorization of objects. A comparison of the best-fit curves shows that the faint-end power-law slopes are markedly different for the two color populations, which indicates that the red and less red Trojans likely formed in different locations. We propose a few hypotheses for the origin and evolution of the Trojan population based on the analyzed data.

  4. Growth and Evolution of Asteroids

    NASA Astrophysics Data System (ADS)

    Asphaug, Erik

    2009-05-01

    Asteroids are what is left of the precursors to the terrestrial planets. They are stunning in their diversity, ranging from charcoal-black worlds the size of a hilltop, spinning like a carnival ride, to dog-bone-shaped metallic remnants of some cataclysmically disrupted planetary core, to worlds as stately as Ceres and Vesta (and fragments thereof), to garden-variety fractured and blocky nuggets that dominate near-Earth space. Asteroid belts are common around Sun-like stars. When properly seen as unaccreted residues, as scraps on the floor of the planetary bakery, the diversity of asteroids can be fully appreciated, for to paraphrase Tolstoy, accreted planets are all alike; every unaccreted planet is unaccreted in its own way.

  5. Benchmarking Asteroid-Deflection Experiment

    NASA Astrophysics Data System (ADS)

    Remington, Tane; Bruck Syal, Megan; Owen, John Michael; Miller, Paul L.

    2016-10-01

    An asteroid impacting Earth could have devastating consequences. In preparation to deflect or disrupt one before it reaches Earth, it is imperative to have modeling capabilities that adequately simulate the deflection actions. Code validation is key to ensuring full confidence in simulation results used in an asteroid-mitigation plan. We are benchmarking well-known impact experiments using Spheral, an adaptive smoothed-particle hydrodynamics code, to validate our modeling of asteroid deflection. We describe our simulation results, compare them with experimental data, and discuss what we have learned from our work. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-695540

  6. Asteroid Return Mission Feasibility Study

    NASA Technical Reports Server (NTRS)

    Brophy, John R.; Gershman, Robert; Landau, Damon; Polk, James; Porter, Chris; Yeomans, Don; Allen, Carlton; Williams, Willie; Asphaug, Erik

    2011-01-01

    This paper describes an investigation into the technological feasibility of finding, characterizing, robotically capturing, and returning an entire Near-Earth Asteroid (NEA) to the International Space Station (ISS) for scientific investigation, evaluation of its resource potential, determination of its internal structure and other aspects important for planetary defense activities, and to serve as a testbed for human operations in the vicinity of an asteroid. Reasonable projections suggest that several dozen candidates NEAs in the size range of interest (approximately 2-m diameter) will be known before the end of the decade from which a suitable target could be selected. The conceptual mission objective is to return an approximately 10,000-kg asteroid to the ISS in a total flight time of approximately 5 years using a single Evolved Expendable Launch Vehicle. Preliminary calculations indicate that this could be accomplished using a solar electric propulsion (SEP) system with high-power Hall thrusters and a maximum power into the propulsion system of approximately 40 kW. The SEP system would be used to provide all of the post-launch delta V. The asteroid would have an unrestricted Earth return Planetary Protection categorization, and would be curated at the ISS where numerous scientific and resource utilization experiments would be conducted. Asteroid material brought to the ground would be curated at the NASA Johnson Space Center. This preliminary study identified several areas where additional work is required, but no show stoppers were identified for the approach that would return an entire 10,000-kg asteroid to the ISS in a mission that could be launched by the end of this decade.

  7. Lightcurve Results for Eleven Asteroids

    NASA Astrophysics Data System (ADS)

    Gartrelle, Gordon M.

    2012-04-01

    Differential photometry techniques were used to develop lightcurves, rotation periods and amplitudes for eleven main-belt asteroids: 833 Monica, 962 Aslog, 1020 Arcadia, 1082 Pirola, 1097 Vicia, 1122 Lugduna, 1145 Robelmonte, 1253 Frisia, 1256 Normannia, 1525 Savolinna, and 2324 Janice. Ground-based observations from Badlands Observatory (BLO) in Quinn, SD, as well as the University of North Dakota Observatory (UND) in Grand Forks, ND, provided the data for the project. A search of the asteroid lightcurve database (LCDB) did not reveal any previously reported results for seven of the eleven targets in this study.

  8. New observations of (4179) Toutatis from the Chang'e-2 flyby mission and future Chinese missions to asteroids

    NASA Astrophysics Data System (ADS)

    Ji, J.

    2014-07-01

    Primitive asteroids are remnant building blocks in the Solar System formation. They provide key clues for us to reach in-depth understanding of the process of planetary formation, the complex environment of early Solar nebula, and even the occurrence of life on the Earth. On 13 December 2012, Chang'e-2 completed a successful flyby of the near-Earth asteroid (4179) Toutatis at a closest distance of 770 meters from the asteroid's surface. The observations show that Toutatis has an irregular surface and its shape resembles a ginger-root with a smaller lobe (head) and a larger lobe (body). Such bifurcated configuration is indicative of a contact binary origin for Toutatis. In addition, the images with a 3-m resolution or higher provide a number of new discoveries about this asteroid, such as an 800-meter basin at the end of the large lobe, a sharply perpendicular silhouette near the neck region, and direct evidence of boulders and regolith, indicating that Toutatis is probably a rubble-pile asteroid. The Chang'e-2 observations have provided significant new insights into the geological features and the formation and evolution of this asteroid. Moreover, a conceptual introduction to future Chinese missions to asteroids, such as the major scientific objectives, scientific payloads, and potential targets, will be briefly given. The proposed mission will benefit a lot from potential international collaboration in the future.

  9. Planetary and asteroid missions. Getting there: Anchoring spacecraft to asteroids

    NASA Technical Reports Server (NTRS)

    Meyer, Rudolf X.; Melko, Joseph P.

    1993-01-01

    In this hardware project, the students developed ideas for attaching objects to the surface of small moons or asteroids. A device was designed, and built in the university machine shop, that uses a projectile shot into concrete, thereby attaching a model spacecraft to the landing site.

  10. Radiometry of near-earth asteroids.

    PubMed

    Veeder, G J; Hanner, M S; Matson, D L; Tedesco, E F; Lebofsky, L A; Tokunaga, A T

    1989-04-01

    We report 10 micrometers infrared photometry for 22 Aten, Apollo, and Amor asteroids. Thermal models are used to derive the corresponding radiometric albedos and diameters. Several of these asteroids appear to have surfaces of relatively high thermal inertia due to the exposure of bare rock or a coarse regolith. The Apollo asteroid 3103, 1982 BB, is recognized as class E. The Jupiter-crossing Amor asteroid 3552, 1983 SA, is confirmed as class D, but low albedos remain rare for near-Earth asteroids.

  11. Radiometry of near-earth asteroids.

    PubMed

    Veeder, G J; Hanner, M S; Matson, D L; Tedesco, E F; Lebofsky, L A; Tokunaga, A T

    1989-04-01

    We report 10 micrometers infrared photometry for 22 Aten, Apollo, and Amor asteroids. Thermal models are used to derive the corresponding radiometric albedos and diameters. Several of these asteroids appear to have surfaces of relatively high thermal inertia due to the exposure of bare rock or a coarse regolith. The Apollo asteroid 3103, 1982 BB, is recognized as class E. The Jupiter-crossing Amor asteroid 3552, 1983 SA, is confirmed as class D, but low albedos remain rare for near-Earth asteroids. PMID:11538320

  12. Depletion of the Outer Asteroid Belt

    NASA Technical Reports Server (NTRS)

    Liou, Jer-Chyi; Malhotra, Renu

    1997-01-01

    During the early history of the solar system, it is likely that the outer planets changed their distance from the sun, and hence, their influence on the asteroid belt evolved with time. The gravitational influence of Jupiter and Saturn on the orbital evolution of asteroids in the outer asteroid belt was calculated. The results show that the sweeping of mean motion resonances associated with planetary migration efficiently destabilizes orbits in the outer asteroid belt on a time scale of 10 million years. This mechanism provides an explanation for the observed depletion of asteroids in that region.

  13. Big bang nucleosynthesis revisited via Trojan Horse method measurements

    SciTech Connect

    Pizzone, R. G.; Spartá, R.; Spitaleri, C.; La Cognata, M.; Tumino, A.; Bertulani, C. A.; Lalmansingh, J.; Lamia, L.; Mukhamedzhanov, A.

    2014-05-10

    Nuclear reaction rates are among the most important input for understanding primordial nucleosynthesis and, therefore, for a quantitative description of the early universe. An up-to-date compilation of direct cross-sections of {sup 2}H(d, p){sup 3}H, {sup 2}H(d, n){sup 3}He, {sup 7}Li(p, α){sup 4}He, and {sup 3}He(d, p){sup 4}He reactions is given. These are among the most uncertain cross-sections used and input for big bang nucleosynthesis calculations. Their measurements through the Trojan Horse method are also reviewed and compared with direct data. The reaction rates and the corresponding recommended errors in this work were used as input for primordial nucleosynthesis calculations to evaluate their impact on the {sup 2}H, {sup 3,4}He, and {sup 7}Li primordial abundances, which are then compared with observations.

  14. Applications of the Trojan Horse method in nuclear astrophysics

    SciTech Connect

    Spitaleri, Claudio

    2015-02-24

    The study of the energy production in stars and related nucleosyntesis processes requires increasingly precise knowledge of the nuclear reaction cross section and reaction rates at interaction energy. In order to overcome the experimental difficulties, arising from small cross-sections involved in charge particle induced reactions at astrophysical energies, and from the presence of electron screening, it was necessary to introduce indirect methods. Trough these methods it is possible to measure cross sections at very small energies and retrieve information on electron screening effect when ultra-low energy direct measurements are available. The Trojan Horse Method (THM) represents the indirect technique to determine the bare nucleus astrophysical S-factor for reactions between charged particles at astrophysical energies. The basic theory of the THM is discussed in the case of non-resonant.

  15. Trojan-horse nanotube on-command intracellular drug delivery.

    PubMed

    Wu, Chia-Hsuan; Cao, Cong; Kim, Jin Ho; Hsu, Chih-Hsun; Wanebo, Harold J; Bowen, Wayne D; Xu, Jimmy; Marshall, John

    2012-11-14

    A major challenge to nanomaterial-based medicine is the ability to release drugs on-command. Here, we describe an innovative drug delivery system based on carbon nanotubes (CNTs), in which compounds can be released inside cells from within the nanotube "on-command" by inductive heating with an external alternating current or pulsed magnetic field. Without inductive heating the drug remains safely inside the CNTs, showing no toxicity in cell viability tests. Similar to the "Trojan-Horse" in function, we demonstrate the delivery of a combination of chemotherapeutic agents with low aqueous solubility, paclitaxel (Taxol), and C6-ceramide, to multidrug resistant pancreatic cancer cells. Nanotube encapsulation permitted the drugs to be used at a 100-fold lower concentration compared to exogenous treatment yet achieve a comparable ~70% cancer kill rate.

  16. Trojan Horse Method: recent results in nuclear astrophysics

    NASA Astrophysics Data System (ADS)

    Spitaleri, C.; Lamia, L.; Gimenez Del Santo, M.; Burjan, V.; Carlin, N.; Li, Chengbo; Cherubini, S.; Crucilla, V.; Gulino, M.; Hons, Z.; Kroha, V.; Irgaziev, B.; La Cognata, M.; Mrazek, J.; Mukhamedzhanov, M.; Munhoz, M. G.; Palmerini, S.; Pizzone, R. G.; Puglia, M. R.; Rapisarda, G. G.; Romano, S.; Sergi, L.; Zhou, Shu-Hua; Somorjai, E.; Souza, F. A.; Tabacaru, G.; Szanto de Toledo, A.; Tumino, A.; Wen, Qungang; Wakabayashi, Y.; Yamaguchi, H.

    2015-07-01

    The accurate knowledge of thermonuclear reaction rates is important in understanding the energy generation, the neutrinos luminosity and the synthesis of elements in stars. The physical conditions under which the majority of astrophysical reactions proceed in stellar environments make it difficult or impossible to measure them under the same conditions in the laboratory. That is why different indirect techniques are being used along with direct measurements. The Trojan Horse Method (THM) is introduced as an independent technique to obtain the bare nucleus astrophysical S(E)-factor. As examples the results of recent the application of THM to the 2H(11B, σ08Be)n and 2H(10B, σ07Be)n reactions are presented.

  17. Dual immunoglobulin light chain B cells: Trojan horses of autoimmunity?

    PubMed

    Pelanda, Roberta

    2014-04-01

    Receptor editing, a major mechanism of B cell tolerance, can also lead to allelic inclusion at the immunoglobulin light chain loci and the development of B cells that coexpress two different immunoglobulin light chains and, therefore, two antibody specificities. Most allelically included B cells express two κ chains, although rare dual-λ cells are also observed. Moreover, these cells typically coexpress an autoreactive and a nonautoreactive antibody. Thus, allelically included B cells could operate like 'Trojan horses': expression and function of the nonautoreactive antigen receptors might promote their maturation, activation, and terminal differentiation into effector cells that also express and secrete autoantibodies. Indeed, dual-κ B cells are greatly expanded into effector B cell subsets in some autoimmune mice, thus indicating they might play an important role in disease.

  18. Flying Through Dust From Asteroids

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-11-01

    How can we tell what an asteroid is made of? Until now, weve relied on remote spectral observations, though NASAs recently launched OSIRIS-REx mission may soon change this by landing on an asteroid and returning with a sample.But what if we could learn more about the asteroids near Earth without needing to land on each one? It turns out that we can by flying through their dust.The aerogel dust collector of the Stardust mission. [NASA/JPL/Caltech]Ejected CluesWhen an airless body is impacted by the meteoroids prevalent throughout our solar system, ejecta from the body are flung into the space around it. In the case of small objects like asteroids, their gravitational pull is so weak that most of the ejected material escapes, forming a surrounding cloud of dust.By flying a spacecraft through this cloud, we could perform chemical analysis of the dust, thereby determining the asteroids composition. We could even capture some of the dust during a flyby (for example, by using an aerogel collector like in the Stardust mission) and bring it back home to analyze.So whats the best place to fly a dust-analyzing or -collecting spacecraft? To answer this, we need to know what the typical distribution of dust is around a near-Earth asteroid (NEA) a problem that scientists Jamey Szalay (Southwest Research Institute) and Mihly Hornyi (University of Colorado Boulder) address in a recent study.The colors show the density distribution for dust grains larger than 0.3 m around a body with a 10-km radius. The distribution is asymmetric, with higher densities on the apex side, shown here in the +y direction. [Szalay Hornyi 2016]Moon as a LaboratoryTo determine typical dust distributions around NEAs, Szalay and Hornyi first look at the distribution of dust around our own Moon, caused by the same barrage of meteorites wed expect to impact NEAs. The Moons dust cloud was measured in situ in 2013 and 2014 by the Lunar Dust Experiment (LDEX) on board the Lunar Atmosphere and Dust Environment

  19. AsteroidZoo: A New Zooniverse project to detect asteroids and improve asteroid detection algorithms

    NASA Astrophysics Data System (ADS)

    Beasley, M.; Lewicki, C. A.; Smith, A.; Lintott, C.; Christensen, E.

    2013-12-01

    We present a new citizen science project: AsteroidZoo. A collaboration between Planetary Resources, Inc., the Zooniverse Team, and the Catalina Sky Survey, we will bring the science of asteroid identification to the citizen scientist. Volunteer astronomers have proved to be a critical asset in identification and characterization of asteroids, especially potentially hazardous objects. These contributions, to date, have required that the volunteer possess a moderate telescope and the ability and willingness to be responsive to observing requests. Our new project will use data collected by the Catalina Sky Survey (CSS), currently the most productive asteroid survey, to be used by anyone with sufficient interest and an internet connection. As previous work by the Zooniverse has demonstrated, the capability of the citizen scientist is superb at classification of objects. Even the best automated searches require human intervention to identify new objects. These searches are optimized to reduce false positive rates and to prevent a single operator from being overloaded with requests. With access to the large number of people in Zooniverse, we will be able to avoid that problem and instead work to produce a complete detection list. Each frame from CSS will be searched in detail, generating a large number of new detections. We will be able to evaluate the completeness of the CSS data set and potentially provide improvements to the automated pipeline. The data corpus produced by AsteroidZoo will be used as a training environment for machine learning challenges in the future. Our goals include a more complete asteroid detection algorithm and a minimum computation program that skims the cream of the data suitable for implemention on small spacecraft. Our goal is to have the site become live in the Fall 2013.

  20. The Main-belt Asteroid and NEO Tour with Imaging and Spectroscopy (MANTIS)

    NASA Astrophysics Data System (ADS)

    Rivkin, A.; Cohen, B. A.; Barnouin, O. S.; Chabot, N. L.; Ernst, C. M.; Klima, R. L.; Helbert, J.; Sternovsky, Z.

    2015-12-01

    The asteroids preserve information from the earliest times in solar system history, with compositions in the population reflecting the material in the solar nebula and experiencing a wide range of temperatures. Today they experience ongoing processes, some of which are shared with larger bodies but some of which are unique to their size regime. They are critical to humanity's future as potential threats, resource sites, and targets for human visitation. However, over twenty years since the first spacecraft encounters with asteroids, they remain poorly understood. The mission we propose here, the Main-belt Asteroid and NEO Tour with Imaging and Spectroscopy (MANTIS), explores the diversity of asteroids to understand our solar system's past history, its present processes, and future opportunities and hazards. MANTIS addresses many of NASA's highest priorities as laid out in its 2014 Science Plan and provides additional benefit to the Planetary Defense and Human Exploration communities via a low-risk, cost-effective tour of the near-Earth and inner asteroid belt. MANTIS visits the materials that witnessed solar system formation and its earliest history, addressing the NASA goal of exploring and observing the objects in the solar system to understand how they formed and evolve. MANTIS measures OH, water, and organic materials via several complementary techniques, visiting and sampling objects known to have hydrated minerals and addressing the NASA goal of improving our understanding of the origin and evolution of life on Earth. MANTIS studies the geology and geophysics of nine diverse asteroids, with compositions ranging from water-rich to metallic, representatives of both binary and non-binary asteroids, and sizes covering over two orders of magnitude, providing unique information about the chemical and physical processes shaping the asteroids, addressing the NASA goal of advancing the understanding of how the chemical and physical processes in our solar system

  1. Periodic motion near the surface of asteroids

    NASA Astrophysics Data System (ADS)

    Jiang, Yu; Baoyin, Hexi; Li, Hengnian

    2015-12-01

    We are interested in the periodic motion and bifurcations near the surface of an asteroid. The gravity field of an irregular asteroid and the equation of motion of a particle near the surface of an asteroid are studied. The periodic motions around the major body of triple asteroid 216 Kleopatra and the OSIRIS-REx mission target-asteroid 101955 Bennu are discussed. We find that motion near the surface of an irregular asteroid is quite different from the motion near the surface of a homoplastically spheroidal celestial body. The periodic motions around the asteroid 101955 Bennu and 216 Kleopatra indicate that the geometrical shapes of the orbits are probably very sophisticated. There exist both stable periodic motions and unstable periodic motions near the surface of the same irregular asteroid. This periodic motion which is unstable can be resonant or non-resonant. The period-doubling bifurcation and pseudo period-doubling bifurcation of periodic orbits coexist in the same gravity field of the primary of the triple asteroid 216 Kleopatra. It is found that both of the period-doubling bifurcations of periodic orbits and pseudo period-doubling bifurcation of periodic orbits have four different paths. The pseudo period-doubling bifurcation found in the potential field of primary of triple asteroid 216 Kleopatra shows that there exist stable periodic orbits near the primary's equatorial plane, which gives an explanation for the motion stability of the triple asteroid 216 Kleopatra's two moonlets, Alexhelios and Cleoselene.

  2. Resonant Structure of the THEMIS Asteroid Family

    NASA Astrophysics Data System (ADS)

    Kehoe, T. J. J.; Murray, C. D.

    1996-09-01

    The existence of resonant structure associated with low-order Jovian mean-motion commensurabilities within the main asteroid belt is already well established. However, previous studies have also suggested evidence for gaps within individual asteroid families. Whereas the Kirkwood gaps in the main asteroid belt are known to result from the actual removal of asteroids from resonant locations, it is not clear if this is also the case for the gaps evident within asteroid families. Indeed, the fact that asteroid families are identified by clustering in proper element space prompted Dermott & Murray (1981) to suggest that some of these gaps might only result from a failure to identify asteroids undergoing resonant perturbations as family members. We have investigated this hypothesis for the particular case of the Themis family of asteroids by numerically integrating the orbits of a carefully created artificial asteroid family. The orbital elements for this artificial family were constructed with proper element distributions closely resembling those of the actual Themis family but with any resonant structure removed. These orbits were then evolved to determine whether asteroids were indeed being removed from resonant locations and to monitor the mechanisms by which this occurred. We present evidence which indicates that the 2:1 Jovian mean-motion resonance may have played an important role in depleting the original Themis asteroid family of some of its members.

  3. The Steward Observatory asteroid relational database

    NASA Technical Reports Server (NTRS)

    Sykes, Mark V.; Alvarezdelcastillo, Elizabeth M.

    1991-01-01

    The Steward Observatory Asteroid Relational Database (SOARD) was created as a flexible tool for undertaking studies of asteroid populations and sub-populations, to probe the biases intrinsic to asteroid databases, to ascertain the completeness of data pertaining to specific problems, to aid in the development of observational programs, and to develop pedagogical materials. To date, SOARD has compiled an extensive list of data available on asteroids and made it accessible through a single menu-driven database program. Users may obtain tailored lists of asteroid properties for any subset of asteroids or output files which are suitable for plotting spectral data on individual asteroids. The program has online help as well as user and programmer documentation manuals. The SOARD already has provided data to fulfill requests by members of the astronomical community. The SOARD continues to grow as data is added to the database and new features are added to the program.

  4. Workshop on Oxygen in Asteroids and Meteorites

    NASA Technical Reports Server (NTRS)

    2005-01-01

    Contents include the following: Constraints on the detection of solar nebula's oxidation state through asteroid observation. Oxidation/Reduction Processes in Primitive Achondrites. Low-Temperature Chemical Processing on Asteroids. On the Formation Location of Asteroids and Meteorites. The Spectral Properties of Angritic Basalts. Correlation Between Chemical and Oxygen Isotopic Compositions in Chondrites. Effect of In-Situ Aqueous Alteration on Thermal Model Heat Budgets. Oxidation-Reduction in Meteorites: The Case of High-Ni Irons. Ureilite Atmospherics: Coming up for Air on a Parent Body. High Temperature Effects Including Oxygen Fugacity, in Pre-Planetary and Planetary Meteorites and Asteroids. Oxygen Isotopic Variation of Asteroidal Materials. High-Temperature Chemical Processing on Asteroids: An Oxygen Isotope Perspective. Oxygen Isotopes and Origin of Opaque Assemblages from the Ningqiang Carbonaceous Chondrite. Water Distribution in the Asteroid Belt. Comparative Planetary Mineralogy: V Systematics in Planetary Pyroxenes and fo 2 Estimates for Basalts from Vesta.

  5. Numeric Modeling of Granular Asteroid Growth

    NASA Astrophysics Data System (ADS)

    Beaumont, Benjamin; Lazzati, D.

    2014-01-01

    It is believed that planetesimals and asteroids are created by the constructive collisions of smaller objects, loosely bound under the effect of self-gravity and/or contact forces. However, the internal dynamics of these collisions and whether they trigger growth or fragmentation are poorly understood. Prior research in the topic has established regimes for the results of constructive collisions of particles under contact forces, but neglects gravity, a critical component once particles are no longer touching, and force chains, an uneven distribution of force inherent to granular materials. We run simulations binary collisions of clusters of particles modeled as hard spheres. Our simulations take into account self-gravity, dissipation of energy, friction, and use a potential function for overlapping particles to study force chains. We present here the collision outcome for clusters with variable masses, particle counts, velocities, and impact parameter. We compare our results to other models and simulations, and find that the collisions remain constructive at higher energies than classically predicted.

  6. Only the first four asteroids

    NASA Astrophysics Data System (ADS)

    Hughes, D. W.

    1997-08-01

    One of the reasons why nobody seriously bothered to look for asteroids in the second and third decade of the nineteenth century was the biblical suspicion that a large planet, when disrupted, would break up into only four pieces; and these four pieces had already been discovered.

  7. NASA's Asteroid Redirect Mission (ARM)

    NASA Astrophysics Data System (ADS)

    Abell, Paul; Mazanek, Dan; Reeves, David; Naasz, Bo; Cichy, Benjamin

    2015-11-01

    The National Aeronautics and Space Administration (NASA) is developing a robotic mission to visit a large near-Earth asteroid (NEA), collect a multi-ton boulder from its surface, and redirect it into a stable orbit around the Moon. Once returned to cislunar space in the mid-2020s, astronauts will explore the boulder and return to Earth with samples. This Asteroid Redirect Mission (ARM) is part of NASA’s plan to advance the technologies, capabilities, and spaceflight experience needed for a human mission to the Martian system in the 2030s. Subsequent human and robotic missions to the asteroidal material would also be facilitated by its return to cislunar space. Although ARM is primarily a capability demonstration mission (i.e., technologies and associated operations), there exist significant opportunities to advance our knowledge of small bodies in the synergistic areas of science, planetary defense, asteroidal resources and in-situ resource utilization (ISRU), and capability and technology demonstrations. In order to maximize the knowledge return from the mission, NASA is organizing an ARM Investigation Team, which is being preceded by the Formulation Assessment and Support Team. These teams will be comprised of scientists, technologists, and other qualified and interested individuals to help plan the implementation and execution of ARM. An overview of robotic and crewed segments of ARM, including the mission requirements, NEA targets, and mission operations, will be provided along with a discussion of the potential opportunities associated with the mission.

  8. The Asteroid Redirect Mission (ARM)

    NASA Technical Reports Server (NTRS)

    Abell, Paul

    2015-01-01

    The National Aeronautics and Space Administration (NASA) is developing a robotic mission to visit a large near-Earth asteroid (NEA), collect a multi-ton boulder from its surface, and redirect it into a stable orbit around the Moon. Once returned to cislunar space in the mid-2020s, astronauts will explore the boulder and return to Earth with samples. This Asteroid Redirect Mission (ARM) is part of NASA's plan to advance the technologies, capabilities, and spaceflight experience needed for a human mission to the Martian system in the 2030s. Subsequent human and robotic missions to the asteroidal material would also be facilitated by its return to cislunar space. Although ARM is primarily a capability demonstration mission (i.e., technologies and associated operations), there exist significant opportunities to advance our knowledge of small bodies in the synergistic areas of science, planetary defense, asteroidal resources and in-situ resource utilization (ISRU), and capability and technology demonstrations. In order to maximize the knowledge return from the mission, NASA is organizing an ARM Investigation Team, which is being preceded by the Formulation Assessment and Support Team. These teams will be comprised of scientists, technologists, and other qualified and interested individuals to help plan the implementation and execution of ARM. An overview of robotic and crewed segments of ARM, including the mission requirements, NEA targets, and mission operations, will be provided along with a discussion of the potential opportunities associated with the mission.

  9. Observations of Planet Crossing Asteroids

    NASA Technical Reports Server (NTRS)

    Tholen, David J.

    1999-01-01

    This grant funds the investigation of the Solar System's planet crossing asteroid population, principally the near Earth and trans-Neptunian objects, but also the Centaurs. Investigations include colorimetry at both visible and near infrared wavelengths, light curve photometry, astrometry, and a pilot project to find near Earth objects with small aphelion distances, which requires observations at small solar elongations.

  10. Lightcurve Analysis of Fourteen Asteroids

    NASA Astrophysics Data System (ADS)

    Pray, Donald P.; Galad, Adrian; Husarik, Marek; Oey, Julian

    2008-03-01

    Lightcurve period and amplitude are reported for the following asteroids observed at Carbuncle Hill Observatory and other sites between December 2006 and March 2007: 1806 Derice, 2472 Bradman, 2480 Popanov, 2768 Gorky, 2874 Jim Young, 3314 Beals, 4936 Butakov, 5676 Voltaire, 6709 Hiromiyuki, 6737 Okabayashi, 9368 Eshashi, 13497 Ronstone, (14142) 1998 SG10 and (46598) 1993 FT2.

  11. SURVEY SIMULATIONS OF A NEW NEAR-EARTH ASTEROID DETECTION SYSTEM

    SciTech Connect

    Mainzer, A.; Bauer, J.; Giorgini, J.; Masiero, J.; Grav, T.; Conrow, T.; Cutri, R. M.; Dailey, J.; Fowler, J.; Jarrett, T.; Spahr, T.; Statler, T.; Wright, E. L.

    2015-05-15

    We have carried out simulations to predict the performance of a new space-based telescopic survey operating at thermal infrared wavelengths that seeks to discover and characterize a large fraction of the potentially hazardous near-Earth asteroid (NEA) population. Two potential architectures for the survey were considered: one located at the Earth–Sun L1 Lagrange point, and one in a Venus-trailing orbit. A sample cadence was formulated and tested, allowing for the self-follow-up necessary for objects discovered in the daytime sky on Earth. Synthetic populations of NEAs with sizes as small as 140 m in effective spherical diameter were simulated using recent determinations of their physical and orbital properties. Estimates of the instrumental sensitivity, integration times, and slew speeds were included for both architectures assuming the properties of newly developed large-format 10 μm HgCdTe detector arrays capable of operating at ∼35 K. Our simulation included the creation of a preliminary version of a moving object processing pipeline suitable for operating on the trial cadence. We tested this pipeline on a simulated sky populated with astrophysical sources such as stars and galaxies extrapolated from Spitzer Space Telescope and Wide-field Infrared Explorer data, the catalog of known minor planets (including Main Belt asteroids, comets, Jovian Trojans, planets, etc.), and the synthetic NEA model. Trial orbits were computed for simulated position-time pairs extracted from the synthetic surveys to verify that the tested cadence would result in orbits suitable for recovering objects at a later time. Our results indicate that the Earth–Sun L1 and Venus-trailing surveys achieve similar levels of integral completeness for potentially hazardous asteroids larger than 140 m; placing the telescope in an interior orbit does not yield an improvement in discovery rates. This work serves as a necessary first step for the detailed planning of a next-generation NEA survey.

  12. Survey Simulations of a New Near-Earth Asteroid Detection System

    NASA Astrophysics Data System (ADS)

    Mainzer, A.; Grav, T.; Bauer, J.; Conrow, T.; Cutri, R. M.; Dailey, J.; Fowler, J.; Giorgini, J.; Jarrett, T.; Masiero, J.; Spahr, T.; Statler, T.; Wright, E. L.

    2015-05-01

    We have carried out simulations to predict the performance of a new space-based telescopic survey operating at thermal infrared wavelengths that seeks to discover and characterize a large fraction of the potentially hazardous near-Earth asteroid (NEA) population. Two potential architectures for the survey were considered: one located at the Earth-Sun L1 Lagrange point, and one in a Venus-trailing orbit. A sample cadence was formulated and tested, allowing for the self-follow-up necessary for objects discovered in the daytime sky on Earth. Synthetic populations of NEAs with sizes as small as 140 m in effective spherical diameter were simulated using recent determinations of their physical and orbital properties. Estimates of the instrumental sensitivity, integration times, and slew speeds were included for both architectures assuming the properties of newly developed large-format 10 μm HgCdTe detector arrays capable of operating at ˜35 K. Our simulation included the creation of a preliminary version of a moving object processing pipeline suitable for operating on the trial cadence. We tested this pipeline on a simulated sky populated with astrophysical sources such as stars and galaxies extrapolated from Spitzer Space Telescope and Wide-field Infrared Explorer data, the catalog of known minor planets (including Main Belt asteroids, comets, Jovian Trojans, planets, etc.), and the synthetic NEA model. Trial orbits were computed for simulated position-time pairs extracted from the synthetic surveys to verify that the tested cadence would result in orbits suitable for recovering objects at a later time. Our results indicate that the Earth-Sun L1 and Venus-trailing surveys achieve similar levels of integral completeness for potentially hazardous asteroids larger than 140 m; placing the telescope in an interior orbit does not yield an improvement in discovery rates. This work serves as a necessary first step for the detailed planning of a next-generation NEA survey.

  13. Survey Simulations of a New Near-Earth Asteroid Detection System

    NASA Astrophysics Data System (ADS)

    Mainzer, A.; Grav, T.; Bauer, J.; Conrow, T.; Cutri, R. M.; Dailey, J.; Fowler, J.; Giorgini, J.; Jarrett, T.; Masiero, J.; Spahr, T.; Statler, T.; Wright, E. L.

    2015-05-01

    We have carried out simulations to predict the performance of a new space-based telescopic survey operating at thermal infrared wavelengths that seeks to discover and characterize a large fraction of the potentially hazardous near-Earth asteroid (NEA) population. Two potential architectures for the survey were considered: one located at the Earth–Sun L1 Lagrange point, and one in a Venus-trailing orbit. A sample cadence was formulated and tested, allowing for the self-follow-up necessary for objects discovered in the daytime sky on Earth. Synthetic populations of NEAs with sizes as small as 140 m in effective spherical diameter were simulated using recent determinations of their physical and orbital properties. Estimates of the instrumental sensitivity, integration times, and slew speeds were included for both architectures assuming the properties of newly developed large-format 10 μm HgCdTe detector arrays capable of operating at ∼35 K. Our simulation included the creation of a preliminary version of a moving object processing pipeline suitable for operating on the trial cadence. We tested this pipeline on a simulated sky populated with astrophysical sources such as stars and galaxies extrapolated from Spitzer Space Telescope and Wide-field Infrared Explorer data, the catalog of known minor planets (including Main Belt asteroids, comets, Jovian Trojans, planets, etc.), and the synthetic NEA model. Trial orbits were computed for simulated position-time pairs extracted from the synthetic surveys to verify that the tested cadence would result in orbits suitable for recovering objects at a later time. Our results indicate that the Earth–Sun L1 and Venus-trailing surveys achieve similar levels of integral completeness for potentially hazardous asteroids larger than 140 m; placing the telescope in an interior orbit does not yield an improvement in discovery rates. This work serves as a necessary first step for the detailed planning of a next-generation NEA survey.

  14. GAIA measurements of asteroid sizes

    NASA Astrophysics Data System (ADS)

    dell'Oro, A.; Cellino, A.

    Observations of Main Belt asteroids by GAIA will produce direct measurements of their angular sizes for a significant sample of the population. A comprehensive set of simulations are currently being performed. They are based on a numerical model specifically developed to simulate the signal that GAIA will receive from asteroids in a large variety of cases. An investigation of the predicted performances of the on-board instrumentation, as currently proposed, is in progress. The simulations take into account all the relevant physical quantities that will play a role in determining the resulting signal, including the apparent angular size of the objects, the possible range of motion in the CCD frames, and photon statistics noise. An analysis of the accuracy of size measurements as a function of apparent magnitude is presented. In spite of the fact that asteroid images will generally cover only small numbers of pixels in the CCD detector and the typical angular sizes of the objects will be generally comparable with the instrumental PSF width, the simulations indicate that relevant information can be extracted from the data in a rather large range of observing conditions. In particular, it turns out that Main Belt asteroids with diameters larger than 30 km will be measured with an accuracy equal or better than 10 %, at least once during the mission operational lifetime. The number of these objects is currently estimated to be of the order of 1000. Below 20 km, no accurate size measurement will be obtained. Simulations have been performed also to investigate the change in expected performances by varying the size of the read-out window of the CCD, in order to determine the best trade-off between the number of read-out pixels and the effect of increasing noise. The proposed 6-pixel width for the faint objects provides an excellent compromise for the purposes of asteroid observations.

  15. The Asteroid Redirect Mission (ARM)

    NASA Astrophysics Data System (ADS)

    Abell, Paul; Gates, Michele; Johnson, Lindley; Chodas, Paul; Mazanek, Dan; Reeves, David; Ticker, Ronald

    2016-07-01

    To achieve its long-term goal of sending humans to Mars, the National Aeronautics and Space Administration (NASA) plans to proceed in a series of incrementally more complex human spaceflight missions. Today, human flight experience extends only to Low-Earth Orbit (LEO), and should problems arise during a mission, the crew can return to Earth in a matter of minutes to hours. The next logical step for human spaceflight is to gain flight experience in the vicinity of the Moon. These cis-lunar missions provide a "proving ground" for the testing of systems and operations while still accommodating an emergency return path to the Earth that would last only several days. Cis-lunar mission experience will be essential for more ambitious human missions beyond the Earth-Moon system, which will require weeks, months, or even years of transit time. In addition, NASA has been given a Grand Challenge to find all asteroid threats to human populations and know what to do about them. Obtaining knowledge of asteroid physical properties combined with performing technology demonstrations for planetary defense provide much needed information to address the issue of future asteroid impacts on Earth. Hence the combined objectives of human exploration and planetary defense give a rationale for the Asteroid Re-direct Mission (ARM). Mission Description: NASA's ARM consists of two mission segments: 1) the Asteroid Redirect Robotic Mission (ARRM), the first robotic mission to visit a large (greater than ~100 m diameter) near-Earth asteroid (NEA), collect a multi-ton boulder from its surface along with regolith samples, demonstrate a planetary defense technique, and return the asteroidal material to a stable orbit around the Moon; and 2) the Asteroid Redirect Crewed Mission (ARCM), in which astronauts will take the Orion capsule to rendezvous and dock with the robotic vehicle, conduct multiple extravehicular activities to explore the boulder, and return to Earth with samples. NASA's proposed

  16. The Formation of Asteroid Satellites in Catastrophic Impacts: Results from Numerical Simulations

    NASA Technical Reports Server (NTRS)

    Durda, D. D.; Bottke, W. F., Jr.; Enke, B. L.; Asphaug, E.; Richardson, D. C.; Leinhardt, Z. M.

    2003-01-01

    We have performed new simulations of the formation of asteroid satellites by collisions, using a combination of hydrodynamical and gravitational dynamical codes. This initial work shows that both small satellites and ejected, co-orbiting pairs are produced most favorably by moderate-energy collisions at more direct, rather than oblique, impact angles. Simulations so far seem to be able to produce systems qualitatively similar to known binaries. Asteroid satellites provide vital clues that can help us understand the physics of hypervelocity impacts, the dominant geologic process affecting large main belt asteroids. Moreover, models of satellite formation may provide constraints on the internal structures of asteroids beyond those possible from observations of satellite orbital properties alone. It is probable that most observed main-belt asteroid satellites are by-products of cratering and/or catastrophic disruption events. Several possible formation mechanisms related to collisions have been identified: (i) mutual capture following catastrophic disruption, (ii) rotational fission due to glancing impact and spin-up, and (iii) re-accretion in orbit of ejecta from large, non-catastrophic impacts. Here we present results from a systematic investigation directed toward mapping out the parameter space of the first and third of these three collisional mechanisms.

  17. Asteroid magnitudes, UBV colors, and IRAS albedos and diameters

    NASA Technical Reports Server (NTRS)

    Tedesco, Edward F.

    1989-01-01

    This paper lists absolute magnitudes and slope parameters for known asteroids numbered through 3318. The values presented are those used in reducing asteroid IR flux data obtained with the IRAS. U-B colors are given for 938 asteroids, and B-V colors are given for 945 asteroids. The IRAS albedos and diameters are tabulated for 1790 asteroids.

  18. Asteroid exploration and utilization: The Hawking explorer

    NASA Technical Reports Server (NTRS)

    Carlson, Alan; Date, Medha; Duarte, Manny; Erian, Neil; Gafka, George; Kappler, Peter; Patano, Scott; Perez, Martin; Ponce, Edgar; Radovich, Brian

    1991-01-01

    The Earth is nearing depletion of its natural resources at a time when human beings are rapidly expanding the frontiers of space. The resources which may exist on asteroids could have enormous potential for aiding and enhancing human space exploration as well as life on Earth. With the possibly limitless opportunities that exist, it is clear that asteroids are the next step for human existence in space. This report comprises the efforts of NEW WORLDS, Inc. to develop a comprehensive design for an asteroid exploration/sample return mission. This mission is a precursor to proof-of-concept missions that will investigate the validity of mining and materials processing on an asteroid. Project STONER (Systematic Transfer of Near Earth Resources) is based on two utilization scenarios: (1) moving an asteroid to an advantageous location for use by Earth; and (2) mining an asteroids and transporting raw materials back to Earth. The asteroid explorer/sample return mission is designed in the context of both scenarios and is the first phase of a long range plane for humans to utilize asteroid resources. The report concentrates specifically on the selection of the most promising asteroids for exploration and the development of an exploration scenario. Future utilization as well as subsystem requirements of an asteroid sample return probe are also addressed.

  19. Binary Planets

    NASA Astrophysics Data System (ADS)

    Ryan, Keegan; Nakajima, Miki; Stevenson, David J.

    2014-11-01

    Can a bound pair of similar mass terrestrial planets exist? We are interested here in bodies with a mass ratio of ~ 3:1 or less (so Pluto/Charon or Earth/Moon do not qualify) and we do not regard the absence of any such discoveries in the Kepler data set to be significant since the tidal decay and merger of a close binary is prohibitively fast well inside of 1AU. SPH simulations of equal mass “Earths” were carried out to seek an answer to this question, assuming encounters that were only slightly more energetic than parabolic (zero energy). We were interested in whether the collision or near collision of two similar mass bodies would lead to a binary in which the two bodies remain largely intact, effectively a tidal capture hypothesis though with the tidal distortion being very large. Necessarily, the angular momentum of such an encounter will lead to bodies separated by only a few planetary radii if capture occurs. Consistent with previous work, mostly by Canup, we find that most impacts are disruptive, leading to a dominant mass body surrounded by a disk from which a secondary forms whose mass is small compared to the primary, hence not a binary planet by our adopted definition. However, larger impact parameter “kissing” collisions were found to produce binaries because the dissipation upon first encounter was sufficient to provide a bound orbit that was then rung down by tides to an end state where the planets are only a few planetary radii apart. The long computational times for these simulation make it difficult to fully map the phase space of encounters for which this outcome is likely but the indications are that the probability is not vanishingly small and since planetary encounters are a plausible part of planet formation, we expect binary planets to exist and be a non-negligible fraction of the larger orbital radius exoplanets awaiting discovery.

  20. Asteroid taxonomic signatures from photometric phase curves

    NASA Astrophysics Data System (ADS)

    Oszkiewicz, Dagmara Anna; Bowell, Edward; Wasserman, L. H.; Muinonen, Karri; Penttilä, Antti; Pieniluoma, Tuomo; Trilling, David E.; Thomas, Cristina A.

    2012-05-01

    We explore the correlation between an asteroid's taxonomy and photometric phase curve using the H, G12 photometric phase function, with the shape of the phase function described by the single parameter G12. We explore the usability of G12 in taxonomic classification for individual objects, asteroid families, and dynamical groups. We conclude that the mean values of G12 for the considered taxonomic complexes are statistically different, and also discuss the overall shape of the G12 distribution for each taxonomic complex. Based on the values of G12 for about half a million asteroids, we compute the probabilities of C, S, and X complex membership for each asteroid. For an individual asteroid, these probabilities are rather evenly distributed over all of the complexes, thus preventing meaningful classification. We then present and discuss the G12 distributions for asteroid families, and predict the taxonomic complex preponderance for asteroid families given the distribution of G12 in each family. For certain asteroid families, the probabilistic prediction of taxonomic complex preponderance can clearly be made. In particular, the C complex preponderant families are the easiest to detect, the Dora and Themis families being prime examples of such families. We continue by presenting the G12-based distribution of taxonomic complexes throughout the main asteroid belt in the proper element phase space. The Nysa-Polana family shows two distinct regions in the proper element space with different G12 values dominating in each region. We conclude that the G12-based probabilistic distribution of taxonomic complexes through the main belt agrees with the general view of C complex asteroid proportion increasing towards the outer belt. We conclude that the G12 photometric parameter cannot be used in determining taxonomic complex for individual asteroids, but it can be utilized in the statistical treatment of asteroid families and different regions of the main asteroid belt.

  1. Properties of eclipsing binaries from all-sky surveys - I. Detached eclipsing binaries in ASAS, NSVS, and LINEAR

    NASA Astrophysics Data System (ADS)

    Lee ( ), Chien-Hsiu

    2015-11-01

    Eclipsing binaries provide a unique opportunity to measure fundamental properties of stars. With the advent of all-sky surveys, thousands of eclipsing binaries have been reported, yet their light curves are not fully exploited. The goal of this work is to make use of the eclipsing binary light curves delivered by all-sky surveys. We attempt to extract physical parameters of the binary systems from their light curves and colour. Inspired by the work of Devor et al., we use the Detached Eclipsing Binary Light curve fitter (DEBIL) and the Method for Eclipsing Component Identification (MECI) to derive basic properties of the binary systems reported by the All Sky Automated Survey, the Northern Sky Variability Survey, and the Lincoln Near Earth Asteroids Research. We derive the mass, fractional radius, and age for 783 binary systems. We report a subsample of eccentric systems and compare their properties to the tidal circularization theory. With MECI, we are able to estimate the distance of the eclipsing binary systems and use them to probe the structure of the Milky Way. Following the approach of Devor et al., we demonstrate that DEBIL and MECI are instrumental to investigate eclipsing binary light curves in the era of all-sky surveys, and provide estimates of stellar parameters of both binary components without spectroscopic information.

  2. A Comparison of Hildas and Jupiter Trojans Using Photometry, Spectroscopy, and Size Distributions

    NASA Astrophysics Data System (ADS)

    Wong, Ian; Brown, Michael E.

    2016-10-01

    The current paradigm of Solar System evolution describes a scenario in which Jupiter and Saturn crossed their mutual 2:1 mean-motion resonance, leading to a period of dynamical instability and significant restructuring of the orbital architecture throughout the middle and outer Solar System. Simulations have shown that the initial minor body populations in resonance with Jupiter (Hildas and Jupiter Trojans) were first emptied during this chaotic episode, and then replaced primarily with objects scattered inward from the trans-Neptunian region. The major implication of these models is that Kuiper Belt objects, Trojans, and Hildas are expected to share a common progenitor population in the outer Solar System. By comparing the properties of Hildas and Trojans, we can evaluate their similarities and/or differences and thereby empirically test current dynamical instability models.Our present understanding of Hildas and Trojans reveals many notable similarities. Beyond sharing the general characteristics of reddish colors and very low albedos, both minor body populations have been shown to display a color bimodality. Building on previously published works, we have derived spectral slopes from the Sloan Moving Object Catalog for both Hildas and Trojans, which reveal a robust bifurcation in the optical color distribution over a wide range of sizes and indicate the presence of two classes of objects within the Hildas and Trojans, referred to as the less-red and red sub-populations. We present the first direct comparison between the Hilda and Trojan magnitude distributions, as well as the individual less-red and red population magnitude distributions; we discuss these results in the context of collisional processes and surface properties. We have also obtained new near-infrared spectra of Hildas from the Infrared Telescope Facility and Keck Observatory, covering the wavelength range 0.8–4.0 microns, which supplement previously-obtained spectra for Trojans in the same

  3. Near Earth Asteroid Characteristics for Asteroid Threat Assessment

    NASA Astrophysics Data System (ADS)

    Dotson, J.; Wooden, D. H.; Bryson, K.; Ostrowski, D. R.

    2015-12-01

    Information about the physical characteristics of Near Earth Asteroids (NEAs) is needed to model behavior during atmospheric entry, to assess the risk of an impact, and to model possible mitigation techniques. The intrinsic properties of interest to entry and mitigation modelers, however, rarely are directly measureable. Instead we measure other properties and infer the intrinsic physical properties, so determining the complete set of characteristics of interest is far from straightforward. In addition, for the majority of NEAs, only the basic measurements exist so often properties must be inferred from statistics of the population of more completely characterized objects. We will provide an assessment of the current state of knowledge about the physical characteristics of importance to asteroid threat assessment. In addition, an ongoing effort to collate NEA characteristics into a readily accessible database for use by the planetary defense community will be discussed.

  4. MarcoPolo-R near earth asteroid sample return mission

    NASA Astrophysics Data System (ADS)

    Barucci, Maria Antonietta; Cheng, A. F.; Michel, P.; Benner, L. A. M.; Binzel, R. P.; Bland, P. A.; Böhnhardt, H.; Brucato, J. R.; Campo Bagatin, A.; Cerroni, P.; Dotto, E.; Fitzsimmons, A.; Franchi, I. A.; Green, S. F.; Lara, L.-M.; Licandro, J.; Marty, B.; Muinonen, K.; Nathues, A.; Oberst, J.; Rivkin, A. S.; Robert, F.; Saladino, R.; Trigo-Rodriguez, J. M.; Ulamec, S.; Zolensky, M.

    2012-04-01

    MarcoPolo-R is a sample return mission to a primitive Near-Earth Asteroid (NEA) proposed in collaboration with NASA. It will rendezvous with a primitive NEA, scientifically characterize it at multiple scales, and return a unique sample to Earth unaltered by the atmospheric entry process or terrestrial weathering. MarcoPolo-R will return bulk samples (up to 2 kg) from an organic-rich binary asteroid to Earth for laboratory analyses, allowing us to: explore the origin of planetary materials and initial stages of habitable planet formation; identify and characterize the organics and volatiles in a primitive asteroid; understand the unique geomorphology, dynamics and evolution of a binary NEA. This project is based on the previous Marco Polo mission study, which was selected for the Assessment Phase of the first round of Cosmic Vision. Its scientific rationale was highly ranked by ESA committees and it was not selected only because the estimated cost was higher than the allotted amount for an M class mission. The cost of MarcoPolo-R will be reduced to within the ESA medium mission budget by collaboration with APL (John Hopkins University) and JPL in the NASA program for coordination with ESA's Cosmic Vision Call. The baseline target is a binary asteroid (175706) 1996 FG3, which offers a very efficient operational and technical mission profile. A binary target also provides enhanced science return. The choice of this target will allow new investigations to be performed more easily than at a single object, and also enables investigations of the fascinating geology and geophysics of asteroids that are impossible at a single object. Several launch windows have been identified in the time-span 2020-2024. A number of other possible primitive single targets of high scientific interest have been identified covering a wide range of possible launch dates. The baseline mission scenario of MarcoPolo-R to 1996 FG3 is as follows: a single primary spacecraft provided by ESA, carrying

  5. Characterization of the Avian Trojan Gene Family Reveals Contrasting Evolutionary Constraints

    PubMed Central

    Petrov, Petar; Syrjänen, Riikka; Smith, Jacqueline; Gutowska, Maria Weronika; Uchida, Tatsuya; Vainio, Olli; Burt, David W

    2015-01-01

    “Trojan” is a leukocyte-specific, cell surface protein originally identified in the chicken. Its molecular function has been hypothesized to be related to anti-apoptosis and the proliferation of immune cells. The Trojan gene has been localized onto the Z sex chromosome. The adjacent two genes also show significant homology to Trojan, suggesting the existence of a novel gene/protein family. Here, we characterize this Trojan family, identify homologues in other species and predict evolutionary constraints on these genes. The two Trojan-related proteins in chicken were predicted as a receptor-type tyrosine phosphatase and a transmembrane protein, bearing a cytoplasmic immuno-receptor tyrosine-based activation motif. We identified the Trojan gene family in ten other bird species and found related genes in three reptiles and a fish species. The phylogenetic analysis of the homologues revealed a gradual diversification among the family members. Evolutionary analyzes of the avian genes predicted that the extracellular regions of the proteins have been subjected to positive selection. Such selection was possibly a response to evolving interacting partners or to pathogen challenges. We also observed an almost complete lack of intracellular positively selected sites, suggesting a conserved signaling mechanism of the molecules. Therefore, the contrasting patterns of selection likely correlate with the interaction and signaling potential of the molecules. PMID:25803627

  6. The Asteroid 2000 ET70

    NASA Astrophysics Data System (ADS)

    Vodniza, Alberto Q.; Pereira, M. R.

    2012-10-01

    The asteroid 2000 ET70 (162421) was discovered by Lincoln Laboratory ETS (LINEAR) in New Mexico on March 8, 2000. Whiteley (2001) classified 2000 ET70 as an X-type object: This asteroid belongs to an ambiguous group that includes objects that are large and dark, metallic.The composition of this asteroid is unknown.The asteroid was at 0.0454430 U.A from the Earth on February 19.85956 (2012) and it will be at approximately 0.1503270 A.U from the Earth on August 21.07061 (2012).The asteroid 2000 ET70 was studied by radar in Arecibo and Goldstone. Shantanu Naidu and Jean-Luc Margot studied this object by Arecibo radar (Feb 13-2012) and they suggest that 2000 ET70 is roughly 1.5 km in diameter and that it has a period of rotation of about 9.5 hours. It has an orbital period of 0.92 years.From our Observatory, located in Pasto-Colombia, we captured several pictures, videos and astrometry data during three days. Our data was published by the Minor Planet Center (MPC) and also appears at the web page of NEODyS. Our observatory’s code at the MPC is “H78”. Pictures of the asteroid were captured with the following equipment: 14” LX200 GPS MEADE (f/10 Schmidt-Cassegrain Telescope) and STL-1001 SBIG camera.Astrometry was carried out, and we calculated the orbital elements. We obtained the following orbital parameters: eccentricity = 0.1243231, semi-major axis = 0.94541495 A.U, orbital inclination = 22.32919 deg, longitude of the ascending node = 331.05007 deg, argument of perihelion = 45.20913 deg, orbital period = 0.92 years (335.76 days), mean motion = 1.07218658 deg/d, perihelion distance = 0.82787796 A.U, aphelion distance = 1.06295195 A.U. The parameters were calculated based on 71 observations (2012 Mar. 1-7) with mean residual = 0.262 arcseconds.

  7. Designing Asteroid Impact Scenario Trajectories

    NASA Astrophysics Data System (ADS)

    Chodas, Paul

    2016-05-01

    In order to study some of the technical and geopolitical issues of dealing with an asteroid on impact trajectory, a number of hypothetical impact scenarios have been presented over the last ten years or so. These have been used, for example, at several of the Planetary Defense Conferences (PDCs), as well as in tabletop exercises with the Federal Emergency Management Agency (FEMA), along with other government agencies. The exercise at the 2015 PDC involved most of the attendees, consisted of seven distinct steps (“injects”), and with all the presentations and discussions, took up nearly 10 hours of conference time. The trajectory for the PDC15 scenario was entirely realistic, and was posted ahead of the meeting. It was made available in the NEO Program’s Horizons ephemeris service so that users could , for example, design their own deflection missions. The simulated asteroid and trajectory had to meet numerous very exacting requirements: becoming observable on the very first day of the conference, yet remaining very difficult to observe for the following 7 years, and far enough away from Earth that it was out of reach of radar until just before impact. It had to be undetectable in the past, and yet provide multiple perihelion opportunities for deflection in the future. It had to impact in a very specific region of the Earth, a specific number of years after discovery. When observations of the asteroid are simulated to generate an uncertainty region, that entire region must impact the Earth along an axis that cuts across specific regions of the Earth, the “risk corridor”. This is important because asteroid deflections generally move an asteroid impact point along this corridor. One scenario had a requirement that the asteroid pass through a keyhole several years before impact. The PDC15 scenario had an additional constraint that multiple simulated kinetic impactor missions altered the trajectory at a deflection point midway between discovery and impact

  8. Prospective very young asteroid pairs

    NASA Astrophysics Data System (ADS)

    Galád, A.; Vokrouhlický, D.; Zizka, J.

    2014-07-01

    Several tens of asteroid pairs can be discerned from the background main-belt asteroids. The majority of them are thought to have formed within only the last few 10^6 yr. The youngest recognized pairs have formed more than ≈ 10 kyr ago. As some details of pair formation are still not understood well, the study of young pairs is of great importance. It is mainly because the conditions at the time of the pair formation could be deduced much more reliably for young pairs. For example, space weathering on the surfaces of the components, or changes in their rotational properties (in spin rates, tumbling, coordinates of rotational pole) could be negligible since the formation of young pairs. Also, possible strong perturbations by main-belt bodies on pair formation can be reliably studied only for extremely young pairs. Some pairs can quickly blend in with the background asteroids, so even the frequency of asteroid pair formation could be determined more reliably based on young pairs (though only after a statistically significant sample is at disposal). In our regular search for young pairs in the growing asteroid database, only multiopposition asteroids with very similar orbital and proper elements are investigated. Every pair component is represented by a number of clones within orbital uncertainties and drifting in semimajor axis due to the Yarkovsky effect. We found that, if the previously unrecognized pairs (87887) 2000 SS_{286} - 2002 AT_{49} and (355258) 2007 LY_{4} - 2013AF_{40} formed at the recent very close approach of their components, they could become the youngest known pairs. In both cases, the relative encounter velocities of the components were only ˜ 0.1 m s^{-1}. However, the minimum distances between some clones are too large and a few clones of the latter pair did not encounter recently (within ≈ 10 kyr). The age of some prospective young pairs cannot be determined reliably without improved orbital properties (e.g., the second component of a pair

  9. Two cubesat mission to study the Didymos asteroid system

    NASA Astrophysics Data System (ADS)

    Wahlund, J.-E.; Vinterhav, E.; Trigo-Rodríguez, J. M.; Hallmann, M.; Barabash, S.; Ivchenko, N.

    2015-10-01

    record the impact event from a closer vantage point than the main spacecraft. The two CubeSats are equipped with relative navigation systems capable of estimating the spacecraft position relative to the asteroids and propulsion system that allow them to operate close to the asteroid bodies. The two CubeSats will rely on mapping data relayed via the AIM main spacecraft but operate autonomously and individually based on schedules and navigation maps uploaded from ground. AIDA's target is the binary Apollo asteroid 65803 Didymos that is also catalogued as Potentially Hazardous Asteroid (PHA) because it experiences close approaches to Earth. Didymos' primary has a diameter of ˜800 meters and the secondary is ˜150 m across. Both bodies are separated about 1.1 km [3]. The rotation period and asymmetry of the secondary object is unknown, and it might be tidally locked to the larger primary body. At least the primary body is expected to be associated with ordinary chondrite material, consisting mostly of silicates, and metal, but the earlier made Xk classification suggested a rubble-pile type with large amount of volatile content. The secondary companion spectral class is unknown, but the total mass of the system suggests that the secondary companion could be of similar class. Detailed empirical information on the physical properties of the Didymos asteroid system, in particular the magnetic field, the (mineralogical) surface composition, the internal composition via the bulk density, the ages of surface units through crater counts and other morphological surface features is valuable in order to make progress in the asteroid field of science. Furthermore, the periodic effect of such a close dynamic system in the presence and temporal displacement of the surface regolith is EPSC Abstracts Vol. 10, EPSC2015-698, 2015 European Planetary Science Congress 2015 c Author(s) 2015 EPSC European Planetary Science Congress unknown, and could be followed using close-up video systems

  10. The Asteroid Redirect Mission (ARM)

    NASA Astrophysics Data System (ADS)

    Abell, Paul; Gates, Michele; Johnson, Lindley; Chodas, Paul; Mazanek, Dan; Reeves, David; Ticker, Ronald

    2016-07-01

    To achieve its long-term goal of sending humans to Mars, the National Aeronautics and Space Administration (NASA) plans to proceed in a series of incrementally more complex human spaceflight missions. Today, human flight experience extends only to Low-Earth Orbit (LEO), and should problems arise during a mission, the crew can return to Earth in a matter of minutes to hours. The next logical step for human spaceflight is to gain flight experience in the vicinity of the Moon. These cis-lunar missions provide a "proving ground" for the testing of systems and operations while still accommodating an emergency return path to the Earth that would last only several days. Cis-lunar mission experience will be essential for more ambitious human missions beyond the Earth-Moon system, which will require weeks, months, or even years of transit time. In addition, NASA has been given a Grand Challenge to find all asteroid threats to human populations and know what to do about them. Obtaining knowledge of asteroid physical properties combined with performing technology demonstrations for planetary defense provide much needed information to address the issue of future asteroid impacts on Earth. Hence the combined objectives of human exploration and planetary defense give a rationale for the Asteroid Re-direct Mission (ARM). Mission Description: NASA's ARM consists of two mission segments: 1) the Asteroid Redirect Robotic Mission (ARRM), the first robotic mission to visit a large (greater than ~100 m diameter) near-Earth asteroid (NEA), collect a multi-ton boulder from its surface along with regolith samples, demonstrate a planetary defense technique, and return the asteroidal material to a stable orbit around the Moon; and 2) the Asteroid Redirect Crewed Mission (ARCM), in which astronauts will take the Orion capsule to rendezvous and dock with the robotic vehicle, conduct multiple extravehicular activities to explore the boulder, and return to Earth with samples. NASA's proposed

  11. Earth-crossing asteroids - New discoveries

    NASA Technical Reports Server (NTRS)

    Helin, E. F.

    1982-01-01

    An earth-crossing asteroid is an asteroid whose orbit will intersect the orbit of the earth as a result of secular perturbations. Astronomical observations have led to the discovery of 43 earth-crossing asteroids during the last fifty years. Nearly sixty percent of these were found in the decade 1971-1981. Noteworthy results of the last decade are discussed, taking into account the Aten asteroids, accidental rediscoveries, asteroids of possible cometary origin, candidates for rendezvous and sample return missions, and populations and collision rates with earth. The observed earth-crossing asteroids are listed in a table, and the orbits of earth, Mars, and four Atens projected on ecliptic plane are shown.

  12. Mining the Apollo and Amor asteroids

    NASA Technical Reports Server (NTRS)

    Oleary, B.

    1977-01-01

    Earth-approaching asteroids could provide raw materials for space manufacturing. For certain asteroids the total energy per unit mass for the transfer of asteroidal resources to a manufacturing site in high earth orbit is comparable to that for lunar materials. For logistical reasons the cost may be many times less. Optical studies suggest that these asteroids have compositions corresponding to those of carbonaceous and ordinary chondrites, with some containing large quantities of iron and nickel; other are thought to contain carbon, nitrogen, and hydrogen, elements that appear to be lacking on the moon. The prospect that several new candidate asteroids will be discovered over the next few years increases the likelihood that a variety of asteroidal resource materials can be retrieved on low-energy missions.

  13. Recovering and Mining Asteroids with a Gas-Sealed Enclosure

    NASA Astrophysics Data System (ADS)

    Jenniskens, P.; Damer, B.; Norkus, R.; Pilotz, S.; Grigsby, B.; Adams, C.; Blair, B. R.

    2015-01-01

    The internal structure of weakly consolidated rubble piles and primitive asteroids can be studied closer to home, and such asteroids can be mined, if it is possible to create a gas-sealed enclosure around the asteroid.

  14. A Spectroscopic and Mineralogical Study of Multiple Asteroid Systems

    NASA Astrophysics Data System (ADS)

    Lindsay, Sean S.; Emery, J. P.; Marchis, F.; Enriquez, J.; Assafin, M.

    2013-10-01

    There are currently ~200 identified multiple asteroid systems (MASs). These systems display a large diversity in heliocentric distance, size/mass ratio, system angular momentum, mutual orbital parameters, and taxonomic class. These characteristics are simplified under the nomenclature of Descamps and Marchis (2008), which divides MASs into four types: Type-1 - large asteroids with small satellites; Type-2 - similar size double asteroids; Type-3 - small asynchronous systems; and Type-4 - contact-binary asteroids. The large MAS diversity suggests multiple formation mechanisms are required to understand their origins. There are currently three broad formation scenarios: 1) ejecta from impacts; 2) catastrophic disruption followed by rotational fission; and 3) tidal disruption. The taxonomic class and mineralogy of the MASs coupled with the average density and system angular momentum provide a potential means to discriminate between proposed formation mechanisms. We present visible and near-infrared (NIR) spectra spanning 0.45 - 2.45 μm for 23 Main Belt MASs. The data were primarily obtained using the Southern Astrophysical Research Telescope (SOAR) Goodman High Throughput Spectrograph (August 2011 - July 2012) for the visible data and the InfraRed Telescope Facility (IRTF) SpeX Spectrograph (August 2008 - May 2013) for the IR data. Our data were supplemented using previously published data when necessary. The asteroids' Bus-DeMeo taxonomic classes are determined using the MIT SMASS online classification routines. Our sample includes 3 C-types, 1 X-type, 1 K-type, 1 L-type, 4 V-types, 10 S-types, 2 Sq- or Q-types, and 1 ambiguous classification. We calculate the 1- and 2-μm band centers, depths, and areas to determine the pyroxene mineralogy (molar Fs and Wo) of the surfaces using empirically derived equations. The NIR band analysis allows us to determine the S-type subclasses, S(I) - S(VII), which roughly tracks olivine-pyroxene chemistry. A comparison of the orbital

  15. Regular Motions of Resonant Asteroids

    NASA Astrophysics Data System (ADS)

    Ferraz-Mello, S.

    1990-11-01

    RESUMEN. Se revisan resultados analiticos relativos a soluciones regulares del problema asteroidal eliptico promediados en la vecindad de una resonancia con jupiten Menciona