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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. Earth's Trojan asteroid.

    PubMed

    Connors, Martin; Wiegert, Paul; Veillet, Christian

    2011-07-27

    It was realized in 1772 that small bodies can stably share the same orbit as a planet if they remain near 'triangular points' 60° ahead of or behind it in the orbit. Such 'Trojan asteroids' have been found co-orbiting with Jupiter, Mars and Neptune. They have not hitherto been found associated with Earth, where the viewing geometry poses difficulties for their detection, although other kinds of co-orbital asteroid (horseshoe orbiters and quasi-satellites) have been observed. Here we report an archival search of infrared data for possible Earth Trojans, producing the candidate 2010 TK(7). We subsequently made optical observations which established that 2010 TK(7) is a Trojan companion of Earth, librating around the leading Lagrange triangular point, L(4). Its orbit is stable over at least ten thousand years.

  3. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

    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 (French et al. 2013), mostly from objects ranging from 30-50 km in diameter, as well as more recent observations. We also discuss observations of five sub-20 km Trojans, whose rotation properties are consistent with cometary densities.

  5. 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.

  6. 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.

  7. 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

  8. 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

  9. 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.

  10. 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.

  11. Trojan Asteroids in the Kepler Campaign 6 Field

    NASA Astrophysics Data System (ADS)

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

    2017-03-01

    We report on a Kepler spacecraft survey during the K2 mission to characterize the rotational properties of 56 Trojan asteroids in the L4 cloud. More than one rotational period was observed for 51 of these targets, allowing for well constrained lightcurve rotation periods and amplitudes, five of which are found to be in conflict with previously published values. We find ∼10% of objects have rotational periods longer than 100 hr, an excess of slow rotators 10 times larger than suggested from the literature. Investigation of the rotational frequencies of our Kepler sample when combined with high-quality lightcurves in the literature reveals the distribution of rotational frequencies is non-Maxwellian even when consideration is given to size-dependent variations in rotational rate. From investigation of lightcurve shapes and amplitudes, we estimate the binary fraction within the Trojan population to be ∼6%–36% depending on the methodology utilized to identify binary candidates.

  12. Photometry of 10 Jovian Trojan Asteroids

    NASA Astrophysics Data System (ADS)

    Stephens, Robert D.; French, L. M.; Coley, D. R.; Megna, R.; Wasserman, L. H.

    2012-10-01

    Lightcurves for 10 Jupiter Trojan asteroids were obtained from GMARS Observatory from August 2010 to March 2012. The objects studied include (911) Agamemmnon, (1867) Deiphobus, (4709) Ennomos, (11397) 1998 XX93, (23135) 2000 AN146, (4138) Kalchas, (10247) Ampiaraos, (12714) Alkimos, (16070) 1999RB101, and (24470) 2000 SJ310. Most objects are in the 50-100 km diameter range. Results will be compared with any previous period and amplitude determinations.

  13. On the dynamical structure of the Trojan group of asteroids

    NASA Technical Reports Server (NTRS)

    Zagretdinov, R. V.; Williams, I. P.; Yoshikawa, M.

    1992-01-01

    Using a semi-analytical approach, domains of possible motion for Trojan asteroids were established. It is shown that stable librating motion is possible for both high inclination and high eccentricity. Frequency distributions were also produced for real Trojan asteroids, against differing libration amplitudes and libration periods.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. On the orbital (in)stability of Trojan asteroids in the solar system

    NASA Astrophysics Data System (ADS)

    Lykawka, Patryk Sofia; Horner, Jonathan; Mueller, Thomas

    2013-06-01

    Jupiter and Neptune have currently large populations of asteroids orbiting about their L4 and L5 Lagrange points, also called Trojan asteroids. Because Trojans can evolve on stable orbits with lifetimes over Gyr, the study of these objects can provide crucial insights into the history of the solar system. We performed numerical simulations to investigate the origin and long term evolution of Trojans of the four giant planets. All giant planets were able to capture disk planetesimals as Trojans at the end of planet migration. However, only 25% and 1-5% of captured Jupiter and Neptune Trojans survived after 4 Gyr of dynamical evolution, respectively, while all captured Trojan populations of Saturn and Uranus were lost during that period. In addition, a non-negligible population of observed Trojans have been leaking out from the Trojan clouds, as evidenced by the dynamical states of (1173) Anchises (Jovian Trojan), and 2001 QR322 and 2008 LC18 (Neptunian Trojans).

  20. 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.

  1. 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).

  2. Asteroid 2014 YX_49: a large transient Trojan of Uranus

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

    In the outer Solar system, primordial Trojan asteroids may have remained dynamically stable for billions of years. Several thousands of them accompany Jupiter in its journey around the Sun and a similarly large population may be hosted by Neptune. In addition, recently captured or transient Jovian and Neptunian Trojans are not uncommon. In contrast, no Trojans of Saturn have been found yet and just one Uranian Trojan is known, 2011 QF99. Here, we discuss the identification of a second Trojan of Uranus: 2014 YX49. Like 2011 QF99, 2014 YX49 is a transient L4 Trojan although it orbits at higher inclination (25.55 vs. 10.83), is larger (absolute magnitude of 8.5 vs. 9.7) and its libration period is slightly shorter (5.1 vs. 5.9 kyr); contrary to 2011 QF99, its discovery was not the result of a targeted survey. It is less stable than 2011 QF99; our extensive N-body simulations show that 2014 YX49 may have been following a tadpole trajectory ahead of Uranus for about 60 kyr and it can continue doing so for another 80 kyr. Our analysis suggests that it may remain as co-orbital for nearly 1 Myr. As in the case of 2011 QF99, the long-term stability of 2014 YX49 is controlled by Jupiter and Neptune, but it is currently trapped in the 7:20 mean motion resonance with Saturn. Consistently, the dynamical mechanism leading to the capture into and the ejection from the Trojan state involves ephemeral multibody mean motion resonances.

  3. Revised albedos of Trojan asteroids (911) Agamemnon and (4709) Ennomos

    NASA Astrophysics Data System (ADS)

    Shevchenko, V. G.; Slyusarev, I. G.; Belskaya, I. N.

    2014-01-01

    CCD-photometry was performed for two Jupiter Trojan asteroids (911) Agamemnon and (4709) Ennomos for which the diameters were obtained from occultation events. New data on rotation periods, lightcurve amplitudes, color indices, magnitude-phase slopes, and absolute magnitudes were obtained for these asteroids. We have used the diameters from occultations (166 and 99 km) and new data on absolute magnitudes at the instant occultation (7.95 and 8.85 mag) to revise their albedos to 0.042 (911 Agamemnon) and 0.052 (4709 Ennomos).

  4. Gravitational Influence of a Large Captured Body on the Stability of Jupiter’s Trojan Asteroids

    NASA Astrophysics Data System (ADS)

    Ohtsuki, Keiji; Okayama, Hiroaki

    2015-11-01

    The Trojan asteroids orbit the Sun about the L4 and L5 Lagrangian points of Jupiter. These objects have a wide range of eccentricities and inclinations, and are thought to be captured planetesimals. Since the origin of the Trojan asteroids is expected to provide clues to the dynamical evolution of the planets and small bodies in the Solar System, various models have been proposed, e.g., capture due to gas drag from the solar nebula, capture during Jupiter’s mass growth, or capture during smooth migration of Jupiter. However, such models failed to reproduce some important characteristics of the present Trojan asteroids, such as the total mass of the Trojans, the distribution of orbital elements, or the distribution of the libration amplitudes. On the other hand, recent models for the formation of the Solar System suggest that the giant planets likely experienced significant radial migration and orbital instability after their formation. Studies of capture of Trojan asteroids based on such models of giant planet migration show that icy planetesimals originally in the outer Solar System can be captured into Jupiter’s Trojan regions, and the present total mass as well as the observed orbital characteristics of the Trojan asteroids can be explained in such models. However, in such studies of capture of the Trojan asteroids, asteroids were treated as test particles, thus gravitational interactions between planetesimals are not taken into account. Although effects of gravitational interactions between sufficiently small asteroids may reasonably be neglected, there may have been significantly large objects in the original swam of Trojan asteroids immediately after their capture. In the present study, we assume that a large body was captured into Jupiter’s Trojan region, and examine its dynamical influence on other Trojan asteroids using orbital integration. From the results of our calculations, we will discuss constraints on the mass of bodies existed in the Trojan

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. Long-term evolution of asteroid families among Jovian Trojans

    NASA Astrophysics Data System (ADS)

    Rozehnal, J.; Brož, M.

    2014-07-01

    We updated the database of resonant elements (i.e. the libration amplitude Δ, eccentricity e, inclination I) of Jupiter Trojans and we identified and verified clusters by both the Hierarchical Clustering Method and Monte Carlo simulations, which allow us to assess also the statistical significance of the asteroid families. Apart from the Eurybates family (Brož & Rozehnal 2011), we also found five clusters of potentially collisional origin --- namely families around asteroids (20961) Arkesilaos, (624) Hektor and (9799) 1996 RJ in L4 cloud and (17492) Hippasos and (247341) in L5 cloud. As these clusters fulfill our criteria for collisional families (i.e. statistical significance, albedo homogeneity, steeper SFD than that of background), we tried to simulate their origin and consequential orbital evolution in different scenarios of planetary migration (e.g. Nesvorný et al. 2013). Using the WISE albedos and diameters (Grav et al. 2011, 2012), we constructed size-frequency distributions of Trojans in both the leading/trailing clouds which we compared to SFDs of the families. We then simulated the collisional evolution of the families (using the Boulder code, Morbidelli et al. 2009). The results show that the evolution of bodies larger than D > 50 km is very slow and they exhibit only little evolution over the last 3.85 Gyr (i.e. post-LHB phase). Hence we can consider this part of the SFD as primordial. In the frame of this model, we also tried to constrain ages of the families. We also analyzed the dependence of the total number of catastrophic disruptions on the target diameter.

  12. 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.

  13. 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

  14. 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

  15. Nekhoroshev stability estimates for different models of the Trojan asteroids

    NASA Astrophysics Data System (ADS)

    Efthymiopoulos, Christos

    2005-02-01

    Estimates of the region of Nekhoroshev stability of Jupiter's Trojan asteroids are obtained by a direct (i.e. without use of the normal form) construction of formal integrals near the Lagrangian elliptic equilibrium points. Formal integrals are constructed in the Hamiltonian model of the planar circular restricted three body problem (PCRTBP), and in a mapping model (Sándor et al. 2002) of the same problem for small orbital eccentricities of the asteroids. The analytical estimates are based on the calculation of the size of the remainder of the formal series by a computer program. An analysis is made of the accumulation of small divisors in the series. The most important divisors introduce competing Fourier terms with sizes growing at similar rates as the order of truncation increases. This makes impossible to improve the estimates by considering nearly resonant forms of the formal integrals for particular near-resonances. Improved estimates were obtained in a mapping model of the PCRTBP. The main source of improvement is the use of better variables (Delaunay). Our best estimate represents a maximum libration amplitude D_p=10.6(0) . This is a quite realistic value which demonstrates the usefulness of Nekhoroshev theory.

  16. 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.

  17. The 3-4 μm Spectra of Jupiter Trojan Asteroids

    NASA Astrophysics Data System (ADS)

    Brown, M. E.

    2016-12-01

    To date, reflectance spectra of Jupiter Trojan asteroids have revealed no distinctive absorption features. For this reason, the surface composition of these objects remains a subject of speculation. Spectra have revealed, however, that the Jupiter Trojan asteroids consist of two distinct sub-populations that differ in the optical to near-infrared colors. The origins and compositional differences between the two sub-populations remain unclear. Here, we report the results from a 2.2-3.8 μm spectral survey of a collection of 16 Jupiter Trojan asteroids, divided equally between the two sub-populations. We find clear spectral absorption features centered around 3.1 μm in the less-red population. Additional absorption consistent with that expected from organic materials might also be present. No such features are see in the red population. A strong correlation exists between the strength of the 3.1 μm absorption feature and the optical to near-infrared color of the objects. While, traditionally, absorptions such as these in dark asteroids are modeled as being due to fine-grain water frost, we find it physically implausible that the special circumstances required to create such fine-grained frost would exist on a substantial fraction of the Jupiter Trojan asteroids. We suggest, instead, that the 3.1 μm absorption on Trojans and other dark asteroids could be due to N-H stretch features. Additionally, we point out that reflectivities derived from WISE observations show a strong absorption beyond 4 μm for both populations. The continuum of 3.1 μm features and the common absorption beyond 4 μm might suggest that both sub-populations of Jupiter Trojan asteroids formed in the same general region of the early solar system.

  18. Study of binary asteroids with three space missions

    NASA Astrophysics Data System (ADS)

    Kovalenko, Irina; Doressoundiram, Alain; Hestroffer, Daniel

    Binary and multiple asteroids are common in the Solar system and encountered in various places going from Near-Earth region, to the main-belt, Trojans and Centaurs, and beyond Neptune. Their study can provide insight on the Solar System formation and its subsequent dynamical evolution. Binaries are also objects of high interest because they provide fundamental physical parameters such as mass and density, and hence clues on the early Solar System, or other processes that are affecting asteroid over time. We will present our current project on analysis of such systems based on three space missions. The first one is the Herschel space observatory (ESA), the largest infrared telescope ever launched. Thirty Centaurs and trans-Neptunian binaries were observed by Herschel and the measurement allowed to define size, albedo and thermal properties [1]. The second one is the satellite Gaia (ESA). This mission is designed to chart a three-dimensional map of the Galaxy. Gaia will provide positional measurements of Solar System Objects - including asteroid binaries - with unprecedented accuracy [2]. And the third one is the proposed mission AIDA, which would study the effects of crashing a spacecraft into an asteroid [3]. The objectives are to demonstrate the ability to modify the trajectory of an asteroid, to precisely measure its trajectory change, and to characterize its physical properties. The target of this mission is a binary system: (65803) Didymos. This encompasses orbital characterisations for both astrometric and resolved binaries, as well as unbound orbit, study of astrometric binaries, derivation of densities, and general statistical analysis of physical and orbital properties of trans-Neptunian and other asteroid binaries. Acknowledgements : work supported by Labex ESEP (ANR N° 2011-LABX-030) [1] Müller T., Lellouch E., Stansberry J. et al. 2009. TNOs are Cool: A Survey of the Transneptunian Region. EM&P 105, 209-219. [2] Mignard F., Cellino A., Muinonen K. et

  19. 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.

  20. 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.

  1. A Search for Volatiles and Spectral Variation on the Surfaces of Trojan Asteroids

    NASA Astrophysics Data System (ADS)

    Emery, Joshua P.; Ness, R. G.; Lucas, M. P.

    2013-10-01

    Trojan asteroids comprise a substantial population of primitive bodies confined to Jupiter’s stable Lagrange regions. Because they likely became trapped in these orbits at the end of the initial phase of planetary formation and subsequent migration, the compositions of Trojans provide unique perspectives on chemical and dynamical processes that shaped the Solar System. Ices and organics are of particular interest for understanding Trojan histories. Published near-infrared (0.7 to 4.0 μm) spectra of Trojans show no absorption bands due to H2O or organics. However, if the Trojan asteroids formed at or beyond their present heliocentric distance of 5.2 AU and never spent significant amounts of time closer to the Sun, they should contain H2O ice. Low densities of two Trojan multiple asteroid systems (Patroclus and Hektor) are consistent with the presence of ice. Similarly, cosmochemical and surface irradiation arguments have been used to explain the red spectral slope of Trojans as due to the presence of complex organic molecules. We present near infrared spectra of four Trojan asteroids (3451 Mentor, 3317 Paris, 627 Hektor, and 911 Agamemnon). All objects were observed at the NASA InfraRed Telescope Facility using the SpeX medium resolution spectrograph. Spectra of Mentor and Paris cover the wavelength range 0.7 to 4.0 μm. These observations were designed primarily to look for H2O and organic absorptions in the 3 - 4 μm region. We see no evidence for any absorptions in the spectra of Mentor or Paris. Spectra of Hektor and Agamemnon cover the wavelength range 0.7 to 2.5 μm and span significant fractions of their respective rotation periods. No rotational variability is evident in the spectrum of Hektor. The spectra of Agamemnon may exhibit a very small amount of variability in spectral slope, but analysis is ongoing. We will discuss the implications of these results in terms of Trojan surface compositions.

  2. The olivine-dominated composition of the Eureka family of Mars Trojan asteroids

    NASA Astrophysics Data System (ADS)

    Borisov, G.; Christou, A.; Bagnulo, S.; Cellino, A.; Kwiatkowski, T.; Dell'Oro, A.

    2017-04-01

    We have used the XSHOOTER echelle spectrograph on the European Southern Obseratory (ESO) Very Large Telescope (VLT) to obtain UVB-VIS-NIR (ultraviolet-blue (UVB), visible (VIS) and near-infrared (NIR)) reflectance spectra of two members of the Eureka family of L5 Mars Trojans, in order to test a genetic relationship to Eureka. In addition to obtaining spectra, we also carried out VRI photometry of one of the VLT targets using the 2-m telescope at the Bulgarian National Astronomical Observatory - Rozhen and the two-channel focal reducer. We found that these asteroids belong to the olivine-dominated A, or Sa, taxonomic class. As Eureka itself is also an olivine-dominated asteroid, it is likely that all family asteroids share a common origin and composition. We discuss the significance of these results in terms of the origin of the martian Trojan population.

  3. 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.

  4. 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.

  5. 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

  6. Analysis of Chemical, REP, and SEP missions to the Trojan asteroids

    NASA Technical Reports Server (NTRS)

    Bonfiglio, Eugene P.; Oh, David; Yen, Chen-Wan

    2005-01-01

    Recent studies suggest significant benefits from using 1st and 2nd generation Radioisotope Power Systems (RPS) as a power source for electric propulsion (EP) missions to the outer planets. This study focuses on trajectories to the Trojan asteroids. A high level analysis is performed with chemical trajectories to determine potential canidates for REP trajectory optimization. Extensive analysis of direct trajectories using REP is performed on these candidates. Solar Electric Propulsion (SEP) trajectories are also considered for comparison against REP trajectories.

  7. 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.

  8. 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

  9. 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

  10. TASTER: Trojan ASteroid Tour, Exploration and Rendezvous, a NASA Planetary Science Summer School Mission Design Exercise

    NASA Astrophysics Data System (ADS)

    Diaz-silva, R.; Sayanagi, K. M.; Gil, S.; Diniega, S.; Balcerski, J.; Benneke, B.; Carande, B.; Fraeman, A. A.; Hudson, J. S.; Guzewich, S. D.; Livi, R.; Nahm, A.; Potter, S.; Route, M.; Urban, K. D.; Vasisht, S.; Williams, B.; Budney, C. J.; Lowes, L. L.

    2011-12-01

    A detailed investigation of the Trojan asteroids occupying Jupiter's L4 and L5 Lagrangian points has been identified as a priority for future missions by the 2011 Planetary Science Decadal Survey. Observing these asteroids and getting clear measurements of their physical characteristics and composition may yield answers to fundamental questions relating to the early Solar System. In particular, Trojan asteroids are believed to harbor primordial material dating from the time of its formation. The source region for Trojans is still unknown; the Nice model predicts that some bodies may have originated in the primordial Kuiper belt and were subsequently scattered inward during the migration of Neptune and Uranus and settled in their current location. In alternative models, less radial scattering of small bodies would imply Trojans formed from material at a similar orbital distance to Jupiter. Determination of Trojan composition and structure will help identify their birth location, provide information about the impact history and subsequent evolution. Earth-based observations of size and surface characteristics are sparse; spectral measurements are unable to resolve composition (and show a puzzling lack of volatile signatures), indicating that close-range observation is needed. We present a mission design for a Trojan Tour and Rendezvous mission that is consistent with NASA's New Frontiers candidate recommended by the Decadal Survey, and which is the final result of the 2011 NASA-JPL Planetary Science Summer School Mission Design Exercise. Our proposed mission includes a tour phase that features a 500 km altitude fly-by of 1999 XS143. The spacecraft will then orbit and make detailed observations of 1919FD Agamemnon, a 167 km diameter asteroid located in the leading Lagrangian point (L4), from orbital altitudes of 1000 - 100 km over a 12 month nominal science data capture period. The mission's planned primary observations aim to (1) detect and identify volatile species

  11. The capture of Trojan asteroids by the giant planets during planetary migration

    NASA Astrophysics Data System (ADS)

    Lykawka, P. S.; Horner, J.

    2010-06-01

    Of the four giant planets in the Solar system, only Jupiter and Neptune are currently known to possess swarms of Trojan asteroids - small objects that experience a 1:1 mean motion resonance with their host planet. In Lykawka et al., we performed extensive dynamical simulations, including planetary migration, to investigate the origin of the Neptunian Trojan population. Utilizing the vast amount of simulation data obtained for that work, together with fresh results from new simulations, we here investigate the dynamical capture of Trojans by all four giant planets from a primordial trans-Neptunian disc. We find the likelihood of a given planetesimal from this region being captured on to an orbit within Jupiter's Trojan cloud lies between several times 10-6 and 10-5. For Saturn, the probability is found to be in the range <10-6 to 10-5, whilst for Uranus the probabilities range between 10-5 and 10-4. Finally, Neptune displays the greatest probability of Trojan capture, with values ranging between 10-4 and 10-3. Our results suggest that all four giant planets are able to capture and retain a significant population of Trojan objects from the disc by the end of planetary migration. As a result of encounters with the giant planets prior to Trojan capture, these objects tend to be captured on orbits that are spread over a wide range of orbital eccentricities and inclinations. The bulk of captured objects are to some extent dynamically unstable, and therefore, the populations of these objects tend to decay over the age of the Solar system, providing an important ongoing source of new objects moving on dynamically unstable orbits among the giant planets. Given that a huge population of objects would be displaced by Neptune's outward migration (with a potential cumulative mass a number of times that of the Earth), we conclude that the surviving remnant of the Trojans captured during the migration of the outer planets might be sufficient to explain the currently known Trojan

  12. 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}.

  13. 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.

  14. The heart of the swarm: K2 photometry and rotational characteristics of 56 Jovian Trojan asteroids

    NASA Astrophysics Data System (ADS)

    Szabó, Gy. M.; Pál, A.; Kiss, Cs.; Kiss, L. L.; Molnár, L.; Hanyecz, O.; Plachy, E.; Sárneczky, K.; Szabó, R.

    2017-02-01

    We present fully covered phased light curves for 56 Jovian Trojan asteroids as observed by the K2 mission of the Kepler space telescope. This set of objects has been monitored during Campaign 6 and represents a nearly unbiased subsample of the population of small solar system bodies. We derived precise periods and amplitudes for all Trojans, and found their distributions to be compatible with the previous statistics. We point out, however, that ground-based rotation periods are often unreliable above 20 h, and we find an overabundance of rotation periods above 60 h compared with other minor planet populations. From amplitude analysis we derive a rate of binarity of 20 ± 5%. Our spin rate distribution confirms the previously obtained spin barrier of 5 h and the corresponding 0.5 g cm-3 cometary-like density limit, also suggesting a high internal porosity for Jovian Trojans. One of our targets, asteroid 65227 exhibits a double rotation period, which can either be due to binarity or the outcome of a recent collision.

  15. The Color–Magnitude Distribution of Hilda Asteroids: Comparison with Jupiter Trojans

    NASA Astrophysics Data System (ADS)

    Wong, Ian; Brown, Michael E.

    2017-02-01

    Current models of solar system evolution posit that the asteroid populations in resonance with Jupiter are comprised of objects scattered inward from the outer solar system during a period of dynamical instability. In this paper, we present a new analysis of the absolute magnitude and optical color distribution of Hilda asteroids, which lie in 3:2 mean-motion resonance with Jupiter, with the goal of comparing the bulk properties with previously published results from an analogous study of Jupiter Trojans. We report an updated power-law fit of the Hilda magnitude distribution through H = 14. Using photometric data listed in the Sloan Moving Object Catalog, we confirm the previously reported strong bimodality in visible spectral slope distribution, indicative of two subpopulations with differing surface compositions. When considering collisional families separately, we find that collisional fragments follow a unimodal color distribution with spectral slope values consistent with the bluer of the two subpopulations. The color distributions of Hildas and Trojans are comparable and consistent with a scenario in which the color bimodality in both populations developed prior to emplacement into their present-day locations. We propose that the shallower magnitude distribution of the Hildas is a result of an initially much larger Hilda population, which was subsequently depleted as smaller bodies were preferentially ejected from the narrow 3:2 resonance via collisions. Altogether, these observations provide a strong case supporting a common origin for Hildas and Trojans as predicted by current dynamical instability theories of solar system evolution.

  16. Redistribution of Trojan Asteroids Between L4 and L5 Induced by Planetary Migration. Is it Symmetrical?

    NASA Astrophysics Data System (ADS)

    Kortenkamp, Stephen J.

    2007-10-01

    We used N-body integration to investigate the stability of Trojan-type companions of the giant planets during planetary migration. A series of simulations were performed involving the migrating giant planets plus approximately 1000 test particle Trojans with initial distributions similar to those of Jupiter's current population of Trojan asteroids. A standard planet migration model was used in which the migration speed decreases exponentially with some characteristic time scale. During planetary migration, resonances between the host planet, a second planet and a Trojan can drive it out of the 1:1 resonance (see Kortenkamp et al 2004). Our simulations show that this loss mechanism can deplete Jupiter's initial Trojan population by up to 98%, depending on the migration time scale (slower migration leads to heavier losses). Conversely, the same resonances can also lead to greater stabilization of some Trojans, constricting them to tighter regions around the L4 or L5 Lagrange equilibrium regions. Our modeling shows that a combination of these de-stablizing and stabilizing resonant perturbations can lead to significant redistribution of Trojans between L4 and L5. Furthermore, all of the Jupiter Trojans observed to undergo such a redistribution transitioned from the trailing L5 region into the leading L4 region. However, the number of examples is quite small. Out of only 20 Jupiter Trojans surviving by the time the planets reached their present orbital configuration, just 2 had transitioned from L5 to L4. Redistribution of Neptune Trojans was much more pervasive as several hundred Trojans were observed to transition back and forth between L4 and L5 throughout the migration process. Additional modeling is being conducted to determine if asymmetries in the redistribution of Trojans result from initial choices of orbital and migration parameters or are merely a consequence of small number statistics. [This work is supported by NASA grant NNG06GD94G

  17. Similar origin for low- and high-albedo Jovian Trojans and Hilda asteroids?

    NASA Astrophysics Data System (ADS)

    Marsset, M.; Vernazza, P.; Gourgeot, F.; Dumas, C.; Birlan, M.; Lamy, P.; Binzel, R. P.

    2014-08-01

    Hilda asteroids and Jupiter Trojans are two low-albedo (pv ~ 0.07) populations for which the Nice model predicts an origin in the primordial Kuiper Belt region. However, recent surveys by WISE and the Spitzer Space Telescope (SST) have revealed that ~2% of these objects possess high albedos (pv ≥ 0.15), which might indicate interlopers - that is, objects not formed in the Kuiper Belt - among these two populations. Here, we report spectroscopic observations in the visible and / or near-infrared spectral ranges of twelve high-albedo (pv > 0.15) Hilda asteroids and Jupiter Trojans. These twelve objects have spectral properties similar to those of the low-albedo population, which suggests a similar composition and hence a similar origin for low- and high-albedo Hilda asteroids and Jupiter Trojans. We therefore propose that most high albedos probably result from statistical bias or uncertainties that affect the WISE and SST measurements. However, some of the high albedos may be true and the outcome of some collision-induced resurfacing by a brighter material that could include water ice. Future work should attempt to investigate the nature of this supposedly bright material. The lack of interlopers in our sample allows us to set an upper limit of 0.4% at a confidence level of 99.7% on the abundance of interlopers with unexpected taxonomic classes (e.g., A-, S-, V-type asteroids) among these two populations. Reflectance spectra presented in this paper are available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/568/L7Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile (ESO program ID: 091.C-0247).

  18. 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.

  19. Paris to Hektor: A Concept for a Mission to the Jovian Trojan Asteroids

    NASA Astrophysics Data System (ADS)

    Gold, Robert E.; McNutt, Ralph L.; Napolillo, David H.; Schaefer, Edward D.; Tanzman, Jennifer R.; Fiehler, Douglas I.; Hartka, Theodore J.; Mehoke, Douglas S.; Ostdiek, Paul H.; Persons, David F.; Prockter, Louise M.; Vernon, Steven R.

    2007-01-01

    This paper presents an example of a new class of planetary exploration missions that is been enabled by the combination of the three technologies of advanced radioisotope power systems, electric propulsion, and expendable launch vehicles. These PARIS (Planetary Access with Radioisotope Ion-drive System) missions are optimized for rendezvous with outer solar system bodies in shallow gravity wells. They are low-thrust missions that are launched to a high C3 and use their electric propulsion systems to slow them to enable orbit insertion or landing on the target body. The PARIS spacecraft can be powered by traditional Radioisotope Thermoelectric Generators (RTGs), but will benefit greatly from the improved power-to-mass ratio of Stirling radioisotope generators (SRGs) that results from their high conversion efficiency. These New-Frontiers class missions can carry a significant science payload to the Jovian Trojan asteroids. The Trojans are very primitive bodies located near the Jovian L4 and L5 Lagrange points. The PARIS to Hektor mission 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. There are estimated to be more than 105 Jovian Trojans greater than 1 km in diameter. The PARIS to Hektor spacecraft has a candidate payload that includes wide-field and narrow-field cameras, a UV-Vis-IR spectrograph, gamma-ray and neutron spectrometers, and plasma and energetic particle spectrometers. The power system generates about 900 W and the launch mass is slightly less than 1000 kg. The trip time is 5 years if ``classic'' GPHS RTGs are used for power. Next generation Stirling radioisotope generators (SRGs), with a demonstrated thermal conversion efficiency of > 30% and an estimated specific power of > 8W/kg would reduce the travel time to about 4 years.

  20. Shapes and binary fractions of Jovian Trojans and Hildas through NEOWISE

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

    Jovian Trojans (hereafter, Trojans) and Hildas are indicative of planetary migration patterns since their capture and physical state must be explained by dynamical evolution models. Early models of minimal planetary migration necessitate that Trojans were dynamically captured from the giant planet region (e.g., Marzari & Scholl 1998). The Nice model instead suggests that Trojans were injected from the outer solar system during a period of significant giant planet migration (e.g., Morbidelli et al. 2005). A more recent version of the Nice model suggests that asymmetric scatterings and collisions would have taken place, producing dissimilar L4 and L5 clouds (Nesvorny et al. 2013). Each of these formation scenarios predicts a different origin and/or collisional evolution for Trojans, which can be inferred from rotation properties. Namely, the physical shape as a function of size helps determine the degree of collisional processing (Farinella et al. 1992). Also, the binary fraction as a function of separation between the two components can be used to determine the dominant binary formation mechanism and thus helps characterize the dynamical environment (e.g., Kern & Elliot 2006). Rotational variation usually corresponds to elongated shapes, but high amplitudes (> 0.9 magnitudes; Sheppard & Jewitt 2004) can only be explained by close or contact binaries. Therefore, rotational lightcurves can be used to infer both shape and the presence of a close companion. Motivated by the need for more observational constraints on solar system formation models and a poor understanding of the rotation properties and binary fraction of Trojans and Hildas, we are studying their rotational lightcurve amplitudes using infrared photometry from NEOWISE (Mainzer et al. 2011; Grav et al. 2011) in order to determine debiased rotational lightcurve amplitude distributions for various Trojan subpopulations and for Trojans compared to Hildas. Preliminary amplitude distributions show a large

  1. Occultation evidence for a satellite of the Trojan asteroid (911) Agamemnon

    NASA Astrophysics Data System (ADS)

    Timerson, Bradley; Brooks, John; Conard, Steven; Dunham, David W.; Herald, David; Tolea, Alin; Marchis, Franck

    2013-10-01

    On 2012 January 19, observers in the northeastern United States of America observed an occultation of 8.0-mag HIP 41337 star by the Jupiter-Trojan (911) Agamemnon, including one video recorded with a 36 cm telescope that shows a deep brief secondary occultation that is likely due to a satellite, of about 5 km (most likely 3-10 km) across, at 278±5 km (0.0931″) from the asteroid's center as projected in the plane of the sky. A satellite this small and this close to the asteroid could not be resolved in the available VLT adaptive optics observations of Agamemnon recorded in 2003. The outline of Agamemnon is fit well by an ellipse with dimensions 190.6±0.9 km by 143.8±1.5 km. The angular diameter of HIP 41337 was found to be 0.5±0.1 milli-arcsec. After (624) Hektor, this could be the second Jupiter Trojan asteroid known to possess a small satellite.

  2. Spacecraft stability, dynamics and control near the triangular Lagrange points influenced by multiple Trojan asteroids

    NASA Astrophysics Data System (ADS)

    Trivailo, Olga

    2007-04-01

    In view of the importance of Lagrange points to the exploration and development of space, the dynamics and stability of a satellite were studied under multiple Trojan asteroids influence. Through the use of a numerical simulator developed in MATLAB, consideration was given to the effects of gravitational forces exerted by the asteroids themselves, simulating the resulting insignificant influence of the Trojan asteroids on a satellite placed at the triangular Lagrange points. The study of optimized satellite transfers between triangular Lagrange points allowed the enforcement of multiple, specific, non-linear constraints on critical mission parameters of maximum thrust, mission duration, propellant consumption and accelerations. The optimized transfer trajectory between the two triangular Lagrange points was direction sensitive. That is, the minimum thrust optimized transfer trajectory for a satellite from L4 to L5 was unique and vastly different to that from L5 to L4. A further exciting discovery highlighted that superposition of the latter trajectories formed a perfectly smooth, uninterrupted kidney-shaped loop, fused at the two relevant points of connection. Implications for this phenomenon extend directly to future mission planning.

  3. 6384 Kervin: A Possible Hungaria Binary Asteroid

    NASA Astrophysics Data System (ADS)

    Warner, Brian D.; Aznar Macia, Amadeo

    2016-04-01

    Analysis of CCD photometric observations in late 2015 of the Hungaria asteroid 6384 Kervin indicates that it may be a binary asteroid with a primary lightcurve of P1 = 3.6194 ± 0.0001 h, A1 = 0.06 ± 0.01 mag. The secondary lightcurve parameters are P2 = 15.94 ± 0.01 h, A2 = 0.03 ± 0.01 mag. No mutual events (occultations or eclipses) were observed. However, other indicators give an estimated diameter ratio on the order of Ds/Dp ~ 0.3, possibly greater.

  4. Mission to the Trojan asteroids: Lessons learned during a JPL Planetary Science Summer School mission design exercise

    NASA Astrophysics Data System (ADS)

    Diniega, Serina; Sayanagi, Kunio M.; Balcerski, Jeffrey; Carande, Bryce; Diaz-Silva, Ricardo A.; Fraeman, Abigail A.; Guzewich, Scott D.; Hudson, Jennifer; Nahm, Amanda L.; Potter-McIntyre, Sally; Route, Matthew; Urban, Kevin D.; Vasisht, Soumya; Benneke, Bjoern; Gil, Stephanie; Livi, Roberto; Williams, Brian; Budney, Charles J.; Lowes, Leslie L.

    2013-02-01

    The 2013 Planetary Science Decadal Survey identified a detailed investigation of the Trojan asteroids occupying Jupiter's L4 and L5 Lagrange points as a priority for future NASA missions. Observing these asteroids and measuring their physical characteristics and composition would aid in identification of their source and provide answers about their likely impact history and evolution, thus yielding information about the makeup and dynamics of the early Solar System. We present a conceptual design for a mission to the Jovian Trojan asteroids: the Trojan ASteroid Tour, Exploration, and Rendezvous (TASTER) mission, that is consistent with the NASA New Frontiers candidate mission recommended by the Decadal Survey and the final result of the 2011 NASA-JPL Planetary Science Summer School. Our proposed mission includes visits to two Trojans in the L4 population: a 500 km altitude fly-by of 1999 XS143, followed by a rendezvous with and detailed observations of 911 Agamemnon at orbital altitudes of 1000-100 km over a 12 month nominal science data capture period. Our proposed instrument payload - wide- and narrow-angle cameras, a visual and infrared mapping spectrometer, and a neutron/gamma ray spectrometer - would provide unprecedented high-resolution, regional-to-global datasets for the target bodies, yielding fundamental information about the early history and evolution of the Solar System. Although our mission design was completed as part of an academic exercise, this study serves as a useful starting point for future Trojan mission design studies. In particular, we identify and discuss key issues that can make large differences in the complex trade-offs required when designing a mission to the Trojan asteroids.

  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. Jupiter Magnetospheric Orbiter and Trojan Asteroid Explorer in EJSM (Europa Jupiter System Mission)

    NASA Astrophysics Data System (ADS)

    Sasaki, Sho; Fujimoto, Masaki; Takashima, Takeshi; Yano, Hajime; Kasaba, Yasumasa; Takahashi, Yukihiro; Kimura, Jun; Tsuda, Yuichi; Funase, Ryu; Mori, Osamu

    2010-05-01

    thick. Currently we are studying a mission to Jupiter and one (or two) of Trojan asteroids using a large (100m-scale) solar power sail that can transfer large payload mass as far as Jupiter. Trojan asteroids are primitive bodies with information of the early solar system as well as raw solid materials of Jovian system. According to the mission plan, as the main spacecraft flies by Jupiter, it will deploy a JMO spinner around Jupiter. Proposed instruments on board Trojan spacecraft are cameras, IR spectrometers, XRS, a laser altimeter, and a surface vehicle (if rendezvous with the target is possible). An instrument for measuring cosmic background is also proposed. Currently JEO and JGO will be launched in 2020 and the Trojan spacecraft with JMO shall be launched at the same window. The mission (Trojan-JMO) will take 6 years to Jupiter and 5 years more to a Trojan asteroid around L4. The mission study team also includes J. Kawaguchi, Y. Kawakatsu, and M. Morimoto of JAXA.

  7. 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

  8. A Power Sailer Mission for a Jovian Orbiter and Trojan Asteroid Flybys

    NASA Astrophysics Data System (ADS)

    Kawaguchi, J.

    The paper presents an innovative Solar Power Sail spacecraft mission that ushers the the century's new planetary explorations. The plan has been studied at ISAS/JAXA in Japan for the start of the project in very new future. The mission is defined as an engineering technology demonstrator, similar to the 'Hayabusa' (MUSES-C) that is currently flying toward an asteroid for a world's first sample-return attempt. The spacecraft studied here uses a world's first hybrid photon / ion propulsions taking the advantage of thin film photo-volatic technology. The mission has very new multi-purposes: First of all, the mission aims at flying-bys to the Trojan asteroids for the first time. And it is simply the first spacecraft to the Jupiter's distance powered only by solar cells. Utilizing the power surplus available at the Earth distance, the spacecraft is supposed to drive its ultra-high specific impulse ion engines aboard with the combination of the Earth gravity assist. The intended specific impulse will be 10,000 seconds, almost as 3.3 times efficient as existing contemporary ion engines. Not only the technology demonstration, in addition to the Trojan asteroid flybys, there are still more new innovative science purposes carried by this spacecraft. Among them, what should be emphasized is a background emission mapping excluding ecliptic dust cloud, which is cleared beyond four AU distance from the Sun. This will reveal the fundamental questions as to the extraordinary young stars observed only in deep IR region. Furthermore, this single spacecraft carries both a Jovian orbiter and an atmospheric reentry probe, both of which will constitute a spacious and simultaneous magnetoshere measurement at the Jovian polar region, via a formation flight. This is what has yet been tried so far in long solar planetary exploration history. ISAS/JAXA is now seriously investigating the spacecraft development and it may put a budgetary proposal for the start of the project hopefully very

  9. Tidal and Dynamical Evolution of Binary Asteroids

    NASA Astrophysics Data System (ADS)

    Jacobson, Seth A.; Scheeres, D. J.

    2009-05-01

    We derive a realistic model for the evolution of a tidally perturbed binary, using classical theory, to examine the system just after a spin-up fission event. The spin rate of an asteroid can be increased by the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect -- thermal re-radiation from an asymmetric body, which induces torques that can rotationally accelerate the body. If the asteroid is modeled as a "rubble pile", a collection of gravitationally bound gravel with no tensile strength, increasing the spin rate will lead to a fission process that would resemble that of a viscous fluidic body [Holsapple 2007]. However, high-resolution imagery of an asteroid's constituents indicates that there is a significant distribution of size scales. A specific example is the asteroid Itokawa, which appears to be two such rubble piles in contact with each other [Fujiwara 2006]. The shape of these bodies will be irregular (modeled as tri-axial ellipsoids with a gravitational potential expanded up to second order). Their motions will raise tides on the opposing body. These tides will dissipate energy, potentially providing enough energy loss for the system to settle into a stable orbit. Fissioned binary systems are always initially unstable [Scheeres 2009, 2008]. We expect tidal dissipation rates to vary widely during the initial evolution of the system, due to this instability. The model applies instantaneous tidal torques to determine energy loss. Our preliminary results indicate that tidal energy dissipation could relax the system to a state of relative equilibrium on order 100,000 years, creating systems similar to those observed. Holsapple, K. A., Icarus, 187, 2007. Fujiwara, A., Science, 312, 2006. Scheeres, D., CMDA, 2009 (Accepted Jan 10, 2009). Scheeres, D., AAS, DDA meeting #39, #9.01, 2008.

  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. Spin-Spin Coupling in Asteroidal Binaries

    NASA Astrophysics Data System (ADS)

    Batygin, Konstantin; Morbidelli, Alessandro

    2015-11-01

    Gravitationally bound binaries constitute a substantial fraction of the small body population of the solar system, and characterization of their rotational states is instrumental to understanding their formation and dynamical evolution. Unlike planets, numerous small bodies can maintain a perpetual aspheroidal shape, giving rise to a richer array of non-trivial gravitational dynamics. In this work, we explore the rotational evolution of triaxial satellites that orbit permanently deformed central objects, with specific emphasis on quadrupole-quadrupole interactions. Our analysis shows that in addition to conventional spin-orbit resonances, both prograde and retrograde spin-spin resonances naturally arise for closely orbiting, highly deformed bodies. Application of our results to the illustrative examples of (87) Sylvia and (216) Kleopatra multi-asteroid systems implies capture probabilities slightly below ~10% for leading-order spin-spin resonances. Cumulatively, our results suggest that spin-spin coupling may be consequential for highly elongated, tightly orbiting binary objects.

  13. Eclipse timing variations to detect possible Trojan planets in binary systems

    NASA Astrophysics Data System (ADS)

    Schwarz, R.; Bazsó, Á.; Funk, B.; Zechner, R.

    2015-11-01

    This paper is devoted to study the circumstances favourable to detect Trojan planets in close binary star systems by the help of eclipse timing variations (ETVs). To determine the probability of the detection of such variations with ground-based telescopes and space telescopes (like former missions CoRoT and Kepler and future space missions like PLATO, TESS and CHEOPS), we investigated the dynamics of binary star systems with a planet in tadpole motion. We did numerical simulations by using the full three-body problem as a dynamical model. The stability and the ETVs are investigated by computing stability/ETV maps for different masses of the secondary star and the Trojan planet. In addition, we changed the eccentricity of the possible Trojan planet. By the help of the libration amplitude σ, we could show whether or not all stable objects are moving in tadpole orbits. We can conclude that many amplitudes of ETVs are large enough to detect Earth-like Trojan planets in binary star systems. As an application, we prepared a list of possible candidates.

  14. 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.

  15. ELECTRON IRRADIATION AND THERMAL PROCESSING OF MIXED-ICES OF POTENTIAL RELEVANCE TO JUPITER TROJAN ASTEROIDS

    SciTech Connect

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

    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 H{sub 2}S. We perform a set of experiments to explore the hypothesis advanced by Wong and Brown that links the color bimodality in Jupiter's Trojans to the presence of H{sub 2}S in the surface of their precursors. Non-thermal (10 keV electron irradiation) and thermally driven chemistry of CH{sub 3}OH–NH{sub 3}–H{sub 2}O (“without H{sub 2}S”) and H{sub 2}S–CH{sub 3}OH–NH{sub 3}–H{sub 2}O (“with H{sub 2}S”) 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 H{sub 2}S” mixture experiment shows a rapid consumption of H{sub 2}S molecules and production of OCS molecules after a few hours of irradiation. The heating of the irradiated “with H{sub 2}S” mixture to temperatures above 120 K leads to the appearance of new infrared bands that we provisionally assign to SO{sub 2}and 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.

  16. 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.”

  17. Doublet craters and the tidal disruption of binary asteroids

    NASA Technical Reports Server (NTRS)

    Melosh, H. J.; Stansberry, J. A.

    1991-01-01

    An evaluation is conducted of the possibility that the tidal disruption of a population of contact binary asteroids can account for terrestrial-impact 'doublet' craters. Detailed orbital integrations indicate that while such asteroids are often disrupted by tidal forces outside the Roche limit, the magnitude of the resulting separations is too small to account for the observed doublet craters. It is hypothesized that an initial population of km-scale earth-crossing objects encompassing 10-20 percent binaries must be responsible for doublet impacts, as may be verified by future observations of earth-approaching asteroids.

  18. Formal Integrals and Nekhoroshev Stability in a Mapping Model for the Trojan Asteroids

    NASA Astrophysics Data System (ADS)

    Efthymiopoulos, Christos

    2005-04-01

    A symplectic mapping model for the co-orbital motion (Sándor et al., 2002, Cel. Mech. Dyn. Astr. 84, 355) in the circular restricted three body problem is used to derive Nekhoroshev stability estimates for the Sun Jupiter Trojans. Following a brief review of the analytical part of Nekhoroshev theory, a direct method is developed to construct formal integrals of motion in symplectic mappings without use of a normal form. Precise estimates are given for the region of effective stability based on the optimization of the size of the remainder of the formal series. The stability region found for t=1010 yrs corresponds to a libration amplitude Dp=10.6°. About 30% of asteroids with accurately known proper elements (Milani, 1993, Cel. Mech. Dyn. Astron. 57, 59), at low eccentricities and inclinations, are included within this region. This represents an improvement with respect to previous estimates given in the literature. The improvement is due partly to the choice of better variables, but also to the use of a mapping model, which is a simplification of the circular restricted three body problem.

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. The capture and release of Trojan asteroids by the giant planets during the solar system history

    NASA Astrophysics Data System (ADS)

    Lykawka, P. S.; Horner, J.

    2011-10-01

    Trojan objects can be dynamically stable over billions of years, implying that they carry precious information about the history of the solar system. We performed numerical simulations to investigate the origin and long term evolution of Trojans of the four giant planets. The results suggest all giant planets are able to capture and retain a significant population of Trojan objects from the primordial planetesimal disk after planet migration. In general, captured Trojans yielded a wide range of eccentricities and inclinations. The bulk of captured objects decay over Gyr providing an important source of new objects on unstable orbits. Our results suggest the bulk of observed Jovian and Neptunian Trojan populations are the survivors from a larger captured population, but their high-i component (>20°) remain unexplained so far.

  4. Evidence for an Extrasolar Trojan Asteroid Population from Kepler Phase Curve Stacking

    NASA Astrophysics Data System (ADS)

    Angerhausen, Daniel

    2016-01-01

    We present the results of a statistical search for exo-trojans in the Kepler Data Set. By super-stacking ˜4000 Kepler planets with a total of ˜90000 full orbital curves, searching for an average Trojan transit dip in the Langrange points, we find an upper limit to the average Trojan transiting area (per planet) that corresponds to one body of radius 460 km with 2σ confidence. We find a significant Trojan-like signal in a sub-sample for planets with more and/or larger Trojans for periods >60 days. Our tentative results can and should be checked with improved data from future missions like PLATO 2.0, and can guide planetary formation theories.

  5. Some Dynamic Characteristics of Binary Near-Earth Asteroids

    NASA Astrophysics Data System (ADS)

    Ivanenko, N. V.; Bazyey, O. A.

    2017-02-01

    Tidal acceleration exerted by the terrestrial planets and Jupiter's are determined, orbital resonances to evaluate the motion stability in binary asteroid systems are calculated. Radius of the Hill sphere surrounding the main component in approximation of the planetary three-body problem - the Sun-main component-satellite is calculated. Escape velocities from the surface of the asteroid satellites are found and the conclusion on the possibility of substance loss is made.

  6. 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).

  7. 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.

  8. Binary asteroids in the near-Earth object population.

    PubMed

    Margot, J L; Nolan, M C; Benner, L A M; Ostro, S J; Jurgens, R F; Giorgini, J D; Slade, M A; Campbell, D B

    2002-05-24

    Radar images of near-Earth asteroid 2000 DP107 show that it is composed of an approximately 800-meter-diameter primary and an approximately 300-meter-diameter secondary revolving around their common center of mass. The orbital period of 1.755 +/- 0.007 days and semimajor axis of 2620 +/- 160 meters constrain the total mass of the system to 4.6 +/- 0.5 x 10(11) kilograms and the bulk density of the primary to 1.7 +/- 1.1 grams per cubic centimeter. This system and other binary near-Earth asteroids have spheroidal primaries spinning near the breakup point for strengthless bodies, suggesting that the binaries formed by spin-up and fission, probably as a result of tidal disruption during close planetary encounters. About 16% of near-Earth asteroids larger than 200 meters in diameter may be binary systems.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. Determination of the Period of Binary Asteroid Systems

    NASA Astrophysics Data System (ADS)

    Lust, Nathaniel B.; Britt, D. T.

    2008-09-01

    In the study of asteroids, binary pairs offer a unique window of study. By observing these systems and determining the period of the secondary, it is possible to determine system mass (e.g. Pravec and Hahn 1997; Ryan et al., 2004). With mass and volume, properties such as bulk density and porosity can be derived. At the University of Central Florida we have begun a binary asteroid hunt, in conjunction with the Prague consortium, in order to identify new binary candidates and to better constrain data on known pairs. All of the observations are collected on campus using a 0.5meter f/8.1 Ritchey-Chretien telescope with a SBIG STL-6303E detector. For our first test target we observed the known binary asteroid 107 Camila over a period of six days for approximately six to eight hours a night. The data is then processed using an open source python algorithm developed by Nate Lust. The data is read in, reduced, and compared to a standard star. Once the light curve was generated we make use of the CLEAN algorithm, originally developed by Hogbom (1974), to extract meaningful periods from the light curve.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. Physical Characterization of the Binary Asteroid 66146 (1998 Tu3)

    NASA Astrophysics Data System (ADS)

    Truong, Thien-Tin; Hicks, M.; Mayes, D.; Barajas, T.; Garcia, K.

    2011-01-01

    The near-Earth asteroid 66146 (1998 TU3) was discovered on 1998 October 13 by the LINEAR NEO survey (MPEC 1998-U03). We obtained five nights of Bessel BVRI observations (2010 Aug 6,7,10,12,13 UT) and one night of Bessel R (August 8 PST) at the JPL Table Mountain Observatory (TMO) 0.6-m telescope near Wrightwood, California. These observations were obtained as part of our ongoing survey at TMO of Potentially Hazardous Asteroids (PHAs), planetary radar targets, and low delta-V near-Earth asteroids (NEOs). The object's rotationally averaged colors (B-R=1.238+/-0.011 mag; V-R=0.440+/-0.008 mag; R-I=0.275+/-0.010 mag) were found most compatible with an Sk-type spectral classification (Bus Taxonomy)/S-type (Tholen Taxonomy). This association was obtained through a comparison of our colors with the 1341 asteroid spectra in the SMASS II database (Bus & Binzel 2002). Our classification differs significantly from the Q-type taxonomy reported by Whitely (2002). Assuming a solar phase parameter g=0.15 we performed a period search using standard Fourier techniques. We found a best-fit rotational period Psyn=2.378+/-0.001 hr, in excellent agreement with the 2.3779+/-0.0004 period determined by Richards et al. (2007). The dispersion in the phased single period lightcurve strongly suggests that 1998 TU3 is be a binary system, with variations in observed flux caused by an unresolved, tidally locked secondary companion. Fitting a 2-period model as described by Pravec et al. (2000), we found that our photometry agrees well with a binary model (P1=2.378+/-0.01 hr, P2=28.28+/-0.05 hr). We have three additional nights scheduled for this object at TMO (Oct 8, 9, 10 2010 UT), extending our solar phase coverage and allowing us to refine our rotational models. 1998 TU3 will experience an exceptional apparition in 2012. This object may be a good candidate for shape/pole modeling via lightcurve inversion, especially if photometry can be obtained from both northern and southern hemispheres. We

  1. 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.

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

    NASA Astrophysics Data System (ADS)

    Lederer, Susan 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.

    2012-10-01

    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 2.0 km/s to 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 µm 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. Results on forsterite and orthoenstatite can be found in Jensen, et al., this meeting. Funding was provided by the NASA PG&G grant 09-PGG09-0115, NSF grant AST-1010012, and a Cottrell College Scholarship through the Research Corporation.

  3. 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.

  4. 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

  5. The resonant structure of Jupiter's Trojan asteroids - II. What happens for different configurations of the planetary system

    NASA Astrophysics Data System (ADS)

    Robutel, P.; Bodossian, J.

    2009-10-01

    In a previous paper, we have found that the resonance structure of the present Jupiter Trojan swarms could be split up into four different families of resonances. Here, in a first step, we generalize these families in order to describe the resonances occurring in Trojan swarms embedded in a generic planetary system. The location of these families changes under a modification of the fundamental frequencies of the planets and we show how the resonant structure would evolve during a planetary migration. We present a general method, based on the knowledge of the fundamental frequencies of the planets and on those that can be reached by the Trojans, which makes it possible to predict and localize the main events arising in the swarms during migration. In particular, we show how the size and stability of the Trojan swarms are affected by the modification of the frequencies of the planets. Finally, we use this method to study the global dynamics of the Jovian Trojan swarms when Saturn migrates outwards. Besides the two resonances found by Morbidelli et al. which could have led to the capture of the current population just after the crossing of the 2:1 orbital resonance, we also point out several sequences of chaotic events that can influence the Trojan population.

  6. 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

  7. 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

  8. First known Terrestrial Impact of a Binary Asteroid from a Main Belt Breakup Event

    PubMed Central

    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

  9. 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.

  10. A possible mechanism to explain the lack of binary asteroids among the Plutinos

    NASA Astrophysics Data System (ADS)

    Compère, A.; Farrelly, D.; Lemaître, A.; Hestroffer, D.

    2013-10-01

    Context. Binary asteroids are common in the solar system, including in the Kuiper belt. However, there seems to be a marked disparity between the binary populations in the classical part of the Kuiper belt and the part of the belt in the 3:2 resonance with Neptune - i.e., the region inhabited by the Plutinos. In particular, binary Plutinos are extremely rare. Aims: We study the impact of the 3:2 resonance on the formation of Kuiper belt binaries, according to the Nice model, in order to explain such phenomenon. Methods: Numerical simulations are performed within the 2 + 2 body approximation (Sun/Neptune + binary partners). The MEGNO chaos indicator is used to map out regular and chaotic regions of phase space. Residence times of test (binary) particles within the Hill sphere are compared inside and outside of the 3:2 resonance. The effect of increasing the heliocentric eccentricity of the centre of mass of the binary system is studied. This is done because mean-motion resonances between a planet and an asteroid usually have the effect of increasing the eccentricity of the asteroid. Results: The stable zones in the MEGNO maps are mainly disrupted in the resonant, eccentric case: the number of binary asteroids created in this case is significantly lower than outside the 3:2 resonance. Conclusions: In the 2 + 2 body approximation, the pumping of the eccentricity of the centre of mass of a potential binary destabilises the formation of binaries. This may be a factor in explaining the scarcity of binaries in the Plutino population.

  11. 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.

  12. 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 large

  13. 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.

  14. Thersites: a `jumping' Trojan?

    NASA Astrophysics Data System (ADS)

    Tsiganis, K.; Dvorak, R.; Pilat-Lohinger, E.

    2000-02-01

    In this paper, we examine the dynamical evolution of the asteroid (1868) Thersites, a member of the Trojan belt. Thersites is librating around the Lagrangian point L_4, following, however, a chaotic orbit. The equations of motion for Thersites as well as for a distribution of neighboring initial conditions are integrated numerically for 50 million years in the Outer Solar System model (OSS), which consists of the Sun and the four giant planets. Our results indicate that the probability that this asteroid will eventually escape from the Trojan swarm is rather high. In fact, 20% from our initial distribution escaped within the integration time. Many of the remaining ones also show characteristic `jumps' in the orbital elements, especially the inclination. Secular resonances involving the nodes of the outer planets are found to be responsible for this chaotic behavior. The width of libration and eccentricity values that lead to grossly unstable orbits are calculated and compared with previously known results on the stability of the Trojans. Finally, a very interesting behavior has been observed for one of the escaping asteroids as he `jumped' from L_4 to L_5 where he remained performing a highly inclined libration for ~ 2 Myrs before escaping from the Trojan swarm. According to Homer, Thersites was not only the ugliest of all Greeks that took part in the Trojan war, but also had the most intolerable personality. His nasty habit of making fun of everybody cost him his life, as the last person for whom he spoke ironically about was Achilles, the mightiest warrior of all Greeks, who killed Thersites with just one punch!

  15. 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.

  16. 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.

  17. 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

  18. The two-body interaction potential in the STF tensor formalism: an application to binary asteroids

    NASA Astrophysics Data System (ADS)

    Compère, A.; Lemaître, A.

    2014-08-01

    The symmetric trace free (STF) tensor formalism, developed by Hartmann et al. (Celest Mech Dyn Astron 60:139-159. doi: 10.1007/BF00693097, 1994), is a nice tool, not much used in Celestial Mechanics. It is fully equivalent to the usual spherical harmonics but permits more elegant and compact formulations. The coupling between the gravitational fields of extended bodies with this formalism has been used in Mathis and Le Poncin-Lafitte (Astron Astrophys 497:889-910. doi: 10.1051/0004-6361/20079054, 2009) for binary stars or planetary systems, but not yet applied to binary asteroids. However, binary asteroids are common in the Solar System and usually their study requires a full two rigid body approach. The formulation of the two-body interaction potential in the STF formalism in the full two rigid body problem is detailed and completed in this article. An application to the binary asteroid (66391) 1999 KW4 is presented with a comparison of our results with other results of the literature for validation.

  19. 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.

  20. 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.

  1. 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.

  2. The Trojans' Odyssey space mission

    NASA Astrophysics Data System (ADS)

    Lamy, P.; Vernazza, P.; Groussin, O.; Poncy, J.; Martinot, V.; Hinglais, E.; Bell, J.; Cruikshank, D.; Helbert, J.; Marzari, F.; Morbidelli, A.; Rosenblatt, P.

    2011-10-01

    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 to 7 years as well as the ?V 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 ?V. 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

  3. The Capture of Jupiter Trojans

    NASA Astrophysics Data System (ADS)

    Morbidelli, A.; Nesvorny, D.; Vokrouhlicky, D.

    2013-09-01

    The origin of Jupiter Trojans remained mysterious for decades. Particularly, it was difficult to explain the excitation of the inclinations of the Trojan population [1]. In 2005, Morbidelli et al. [2] proposed a scenario of capture from the trans-Neptunian disk, in the framework of the so-called "Nice model" [3,4]. This scenario explained in a natural way the observed orbital distribution of Trojans. The Nice model, however, evolved in the years, in order to satisfy an increasingly large number of constraints. It now appears that the dynamical evolution of the giant planets was different from that envisioned in [2]. Here, we assess again the process of capture of Trojans within this new evolution. We show that (6-8)×10 - 7 of the original trans-Neptunian planetesimals are captured in the Trojan region, with an orbital distribution consistent with the one observed. Relative to [2], the new capture mechanism has the potential of explaining the asymmetry between the L4 and L5 populations. Moreover, the resulting population of Trojans is consistent with that of the Irregular Satellites of Jupiter, which are captured in the same process; a few bodies from the main asteroid belt could also be captured in the Trojan cloud.

  4. 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.

  5. 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

  6. 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 ...

  7. Dynamics of 'jumping' Trojans: Perturbative treatment

    NASA Astrophysics Data System (ADS)

    Sidorenko, V.

    2014-07-01

    The term ''jumping'' Trojan was introduced by Tsiganis et al. (2000) in their studies of long-term dynamics exhibited by the asteroid (1868) Thersites: as it turned out, this asteroid may pass from the librations around L4 to the librations around L5. One more example of a ''jumping'' Trojan was found by Connors et al. (2011): librations of the asteroid 2010 TK_7 around Earth's libration point L4 preceded by its librations around L5. We explore the dynamics of ''jumping'' Trojans under the scope of the restricted planar elliptical three-body problem. Via double numerical averaging, we construct evolutionary equations which describe the long-term behavior of the orbital elements of these asteroids.

  8. 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

  9. 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.

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

    NASA Astrophysics Data System (ADS)

    Shang, Haibin; Wu, Xiaoyu; Cui, Pingyuan

    2017-02-01

    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.

  11. 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

  12. A Survey for Neptune Trojans

    NASA Astrophysics Data System (ADS)

    Sheppard, Scott; Trujillo, Chad

    2007-02-01

    Trojan asteroids share a planet's semi-major axis but lead or follow the planet by about 60 degrees near the two triangular Lagrangian points of equilibrium. These minor planets were likely captured in these locations around the planet formation epoch and thus their current dynamical and physical properties will help constrain the formation, evolution and migration of the planets. The Neptune Trojans currently consist of only four known objects, all in the leading L4 cloud. Three of these were discovered in our initial survey of the region allowing us to determine that Neptune was likely on a much more eccentric orbit in the distant past (Sheppard and Trujillo 2006). We propose to obtain the first wide-field survey for Neptune Trojans in the trailing L5 region using the CTIO 4m telescope. Only with knowledge of the Neptune Trojan numbers and orbits in both the L4 and L5 clouds will we be able to understand the Trojans formation and evolution. We will also take advantage of the current fortuitous alignment of the Uranus and Neptune Trojan regions to our line of sight to search both regions simultaneously.

  13. 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

  14. 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.

  15. 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.

  16. Extrasolare Trojaner

    NASA Astrophysics Data System (ADS)

    Hippke, Michael; Angerhausen, Daniel

    2017-01-01

    Mit Hilfe der Daten des Satellitenobservatoriums Kepler ist es erstmals gelungen, Trojaner außerhalb unseres Sonnensystems nachzuweisen. Diese Asteroidengattung nimmt bestimmte Positionen - die Lagrange-Punkte L4 und L5 - in der Umlaufbahn eines Planeten ein.

  17. 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.

  18. Thermal inertia of eclipsing binary asteroids: the role of component shape

    NASA Astrophysics Data System (ADS)

    Mueller, Michael; van de Weijgaert, Marlies

    2015-11-01

    Thermal inertia controls the temperature distribution on asteroid surfaces. This is of crucial importance to the Yarkovsky effect and for the planning of spacecraft operations on or near the surface. Additionally, thermal inertia is a sensitive indicator for regolith structure.A uniquely direct way of measuring thermal inertia is through observations of the thermal response to an eclipse in a binary system, when one component shadows the other. This method was pioneered by Mueller et al. (2010), who observed eclipses in (617) Patroclus using Spitzer IRS. Buie et al. (2015) report observations of a stellar occultation by Patroclus. Their estimate for the system's projected size agrees well with the Spitzer result. However, the occultation revealed that the components are much more oblately shaped than was assumed by Mueller et al.This prompted us to study the role of component shape in the analysis of thermal eclipse data. Conceivably, the global shape can have a significant impact on the shape and size of the eclipsed area and therefore on its thermal emission. So far, this has not been studied in a systematic way. Using Patroclus and the existing Spitzer data as our test case, we vary the ellipsoidal component shape and determine the resulting best-fit thermal inertia. This will lead to an updated estimate of Patroclus' thermal inertia, along with a potentially more realistic estimate of its uncertainty. Beyond that, our results will inform ongoing and future thermal studies of other eclipsing binary asteroids.

  19. Synchronous motion in the Kinoshita problem. Application to satellites and binary asteroids

    NASA Astrophysics Data System (ADS)

    Breiter, S.; Melendo, B.; Bartczak, P.; Wytrzyszczak, I.

    2005-07-01

    A Lie-Poisson integrator with Wisdom-Holman type splitting is constructed for the problem of a rigid body and a sphere (the Kinoshita problem). The algorithm propagates not only the position, momentum and angular momentum vector of the system, but also the tangent vector of "infinitesimal displacements". The latter allow to evaluate the maximum Lyapunov exponent or the MEGNO indicator of Cincotta and Simó. Three exemplary cases are studied: the motion of Hyperion, a fictitious binary asteroid with Hyperion as one of the components, and the binary asteroid 90 Antiope. In all cases the attitude instability of the rotation state with spin vector normal to an equatorial orbit influences stability of the system at lower rotation rates. The MEGNO maps with variations restricted to the orbital plane for position and momentum, and to the orbit normal direction for the angular momentum resemble usual Poincaré sections. But if no restriction is imposed on the variations, some stable zones turn into highly chaotic regions, often retaining the shape of their boundaries.

  20. 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.

  1. Current problems of dynamics of moons of planets and binary asteroids based on observations

    NASA Astrophysics Data System (ADS)

    Emel'yanov, N. V.

    2017-01-01

    asteroids were determined this way. One of the principal techniques for Earth-based measurement of the masses of asteroids involves astrometric observations of binary asteroids. The determination of relative coordinates is made rather difficult by the apparent proximity of components. The success of these efforts depends on the availability of instrumentation and the expertise of observers skilled in adaptive optics and speckle interferometry. Collaboration between different research teams and observers is absolutely necessary.

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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

  7. 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

  8. Non-convex model of the binary asteroid (809) Lundia and its density estimation

    NASA Astrophysics Data System (ADS)

    Kryszczynska, A.; Bartczak, P.; Polinska, M.; Colas, F.

    2014-07-01

    Introduction: (809) Lundia was classified as a V-type asteroid in the Flora family (Florczak et.al. 2002). The binary nature of (809) Lundia was discovered in September 2005 based on photometric observations. The first modeling of the Lundia synchronous binary system was based on 22 lightcurves obtained at Borowiec and Pic du Midi Observatories during two oppositions in 2005/2006 and 2006/2007. Two methods of modeling --- modified Roche ellipsoids and kinematic --- gave similar parameters for the system (Kryszczynska et al. 2009). The poles of the orbit in ecliptic coordinates were: longitude 118° and latitude 28° in the modified Roche model and 120°, 18°, respectively, in the kinematic model. The orbital period obtained from the lightcurve analysis as well as from modeling was 15.418 h. The obtained bulk density of both components was 1.64 or 1.71 g/ccm. Observations: We observed (809) Lundia in the 2008, 2009/2010, 2011, and 2012 oppositions at the Borowiec, Pic du Midi, Prompt, and Rozhen Observatories. As predicted, the visible eclipses/occultation events were observed only in 2011. Currently, our dataset consists of 45 individual lightcurves and they were all used in the new modeling. Method: We used new method of modeling based on a genetic algorithm that is able to create a non-convex asteroid shape model, rotational period, and spin-axis orientation of a single or binary asteroid, using only photometric observations. The details of the method are presented in the poster by Bartczak et al., at this conference. Results: The new non-convex model of (809) Lundia is presented in the figure. The parameters of the system in the ecliptic coordinates are: longitude 122°, latitude 22°, and sidereal period 15.41574 h. They are very similar to the values obtained before. However, assuming an equivalent diameter of a single body of 9.1 km from the Spitzer observations (Marchis et al. 2012) and the volume of the two modeled bodies, the separation of the components

  9. Physical Characterization of Binary Near-Earth Asteroid (153958) 2002 AM31

    NASA Astrophysics Data System (ADS)

    Taylor, Patrick A.; Howell, E. S.; Nolan, M. C.; Springmann, A.; Brozovic, M.; Benner, L. M.; Jao, J. S.; Giorgini, J. D.; Margot, J.; Fang, J.; Becker, T. M.; Fernandez, Y. R.; Vervack, R. J.; Pravec, P.; Kusnirak, P.; Franco, L.; Ferrero, A.; Galad, A.; Pray, D. P.; Warner, B. D.; Hicks, M. D.

    2013-10-01

    Arecibo (2380 MHz, 12.6 cm) and Goldstone (8560 MHz, 3.5 cm) radar observations between 2012 July 12 and August 8 revealed that Apollo-class and potentially hazardous asteroid (153958) 2002 AM31 is a binary system. It is comprised of a primary component 400-500 meters in diameter and a possibly asynchronous secondary about one-fourth that size. The most striking characteristics of this system are a significant mutual-orbit eccentricity of ~0.45, one of the largest eccentricities known among near-Earth binaries, and an implied density greater than 3 g/cc (depending on the volumes of the components). The size ratio, the semimajor axis of ~1.5 km, and the mutual-orbit period of ~26.3 h are otherwise typical among near-Earth binaries. Optical lightcurves suggest rapid rotation of the primary in of order 3 h, consistent with radar echo bandwidths, and confirm the mutual-orbit period via the timing of mutual events. Near- and thermal infrared (0.8-4.1 microns) spectroscopy with SpeX on the NASA IRTF places this system in the S complex, and rotationally resolved spectra show no variation in thermal properties as the primary rotates. We will present further refined estimates of the sizes, shapes, and spin states of the components.

  10. Where are the Saturn Trojans?

    NASA Astrophysics Data System (ADS)

    Baudisch, H.; Dvorak, R.

    2012-12-01

    The gas giants Jupiter and Neptune are known to host Trojan asteroids but up to now no asteroids have been found around the libration points of Uranus and Saturn. With the aid of numerical integrations we checked the stability of fictitious bodies in the 1:1 Mean Motion Resonance with Saturn. Former studies show that around the Lagrange points the bodies escape quite fast whereas a stable ring survives for million of years. Using the results of our investigation in different dynamical models we could show that Jupiter is responsible for the unstable hole around the equilateral equilibrium points.

  11. Trojan twin planets

    NASA Astrophysics Data System (ADS)

    Dvorak, R.; Loibnegger, B.; Schwarz, R.

    2017-03-01

    The Trojan asteroids are moving in the vicinity of the stable Lagrange points L_4 and L_5 of the gas giants Jupiter, Uranus and Neptune. Their motion can be described and understood with the aid of the restricted three-body problem. As an extension of this problem we investigate how stable motion close to the Lagrange points of two massive bodies can exist. This configuration can be described as the Trojan Twin Problem when we regard the two additional bodies as having a mass significantly smaller than the the two primary bodies: a star in the center (m_1) and an additional Jupiter-like mass (m_2). Using this 4-body problem we have undertaken numerical investigations concerning possible stable "twin orbits". However, these two bodies (m_3 and m_4) in Trojan-like orbits may have quite different masses. We decided to choose 6 different scenaria for this problem: as primary body, m2, we have taken a Jupiter-like planet, a Saturn-like one, and a super-Earth with 10 Earthmasses (m_{Earth}) respectively. As quasi twin planets, we have used different mass ratios namely objects for m3 and m4 from 10m_{Earth} to Moon like ones. We found different stable configurations depending on the involved masses and the initial distances between the twins (always close to the Lagrange point). Although the formation of such a configuration seems to be not very probable we should not exclude that it exists regarding the huge number of planets even in our own galaxy. This model is of special interest when the most massive planet (m_2) is moving on an orbit in the habitable zone around a main sequence star. One can use our results of stable orbits of Trojan Twin Planets (or asteroids) for extrasolar systems having as second primary a Jupiter-like, a Saturn-like or a super-Earth like planet around a star similar to our Sun.

  12. 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.

  13. Update on Asteroid Density and Porosity

    NASA Astrophysics Data System (ADS)

    Britt, D. T.; Consolmagno, G. J.; Merline, W. J.

    2005-08-01

    Data on the bulk density of small bodies has exploded over the last 10 years (primarily from observations of asteroid satellites) and has led to significant insights into the structure of these objects [1,2]. This has contributed to the consensus that most small bodies have relatively low bulk densities and probably have significant porosity. Since then, new observations and planetary missions have provided a significantly expanded set of data, broadening the range of object types and sizes. These include the small icy moons measured by the Cassini mission, new AO observations of asteroid moons, new observations of small binaries using lightcurve techniques, new observations of NEO and TNO binaries, new data on comet and Centaur density, and new observations of Trojan binaries. These data provide a window into new size ranges and into new zones of the solar system. We review the available data and update our compilations of estimated porosity for small bodies. References: [1] Merline, W.J. et al. (2002) Asteroids III (Bottke W. et al., eds, 289-312. [2] Britt D.T. et al., (2002) Asteroids III (Bottke W. et al., eds), 485-500.

  14. 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

  15. A photometric survey of outer belt asteroids

    NASA Technical Reports Server (NTRS)

    Dimartino, M.; Gonano-Beurer, M.; Mottola, Stefano; Neukum, G.

    1992-01-01

    Since 1989, we have been conducting a research program devoted to the study of the Trojans and outer belt asteroids (Hilda and Cybele groups), in order to characterize their rotational properties and shapes. As an outcome of several observational campaigns, we determined rotational periods and lightcurve amplitudes for 23 distant asteroids, using both CCD and photoelectric photometry. In this paper, we compare the rotational properties of main belt asteroids and Trojans, based on the preliminary results of this survey.

  16. Regulation of Primary Spin Rate of Asynchronous Binary Asteroids by "Tidal Saltation"

    NASA Astrophysics Data System (ADS)

    Harris, Alan W.; Fahnestock, E. G.; Pravec, P.

    2008-05-01

    For asynchronous binary asteroids, the primary is spinning at close to the rate where centrifugal force cancels gravity at the equator. The time varying tidal acceleration from the satellite may nearly cancel, or even reverse, the total acceleration vector on the equator as it passes directly under the satellite. We numerically investigate mass motion of loose regolith under these conditions, using parameters of binary NEA (66391) 1999 KW4, with coefficients of static and sliding friction typical of regolith materials. The onset of mass motion and even levitation off the surface begins when the tidal acceleration is not quite enough to reverse the static acceleration at the sub-satellite point. Sliding motion in the direction of the rising satellite begins when the satellite has risen about half way to the zenith. The added velocity results in the material levitating off the surface and following a ballistic trajectory for a time, re-impacting on the surface after the satellite has passed overhead and is now retarding the levitated matter, causing it to fall back. From the surface of the satellite, the levitated regolith follows a looping trajectory, falling back to a point behind where it launched, opposite the direction of rotation. Viewed from the satellite, the mass motion is a sort of standing wave, like sand saltation at the crest of a sand dune. It also resembles a tidal bulge, but with a "lag angle” close to 45 degrees, maximum for transfer of angular momentum from the spin of the primary to the orbit of the secondary. We suggest that this is the main process by which YORP torque received by the primary is transferred to the orbit of the secondary, thereby regulating the primary spin to very near the critical spin rate, and also producing the smooth "racetrack” profile of the equator.

  17. Spectroscopy and Photometry of Mars Trojans

    NASA Technical Reports Server (NTRS)

    Rivkin, A. S.; Binzel, R. P.; Howell, E. S.; Bus, S. J.; Grier, J. A.

    2003-01-01

    Mars is the only terrestrial planet known to have co-orbiting "Trojan" asteroids. We have obtained visible and near-IR reflectance spectra of three of these objects: 5261 Eureka and 1998 VF31 in the L5 region and 1999 UJ7 in the L4 region. We also obtained JHK spectrophotometry and a visible lightcurve for 5261 Eureka. The asteroid 5261 Eureka has a visible spectrum that is classified as Sr in the Bus taxonomy, and has infrared colors consistent with the A-class asteroids. The data for 1998 VF31 have a restricted wavelength range, but are most consistent with the Sr or Sa class, though we note a marginal consistency with the D class. We can rule out a C-class classification. 1999 UJ7 has an X-class or T-class spectrum, which is unlike that of the other two Mars Trojans. The photometric data for Eureka are limited, but we can constrain the period to longer than 5 hours (likely 5.556 hours) and lightcurve amplitude of at least 0.15 magnitude at this viewing geometry. The spectral differences among the Mars Trojans suggests that either they did not all form at their present solar distances or that they have not always been at their present sizes. 0 2003 Elsevier Inc. All rights reserved. Keywords: Asteroids; Asteroids, composition; Spectroscopy; Satellites of Mars

  18. 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.

  19. 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

  20. Survival of water ice in Jupiter Trojans

    NASA Astrophysics Data System (ADS)

    Guilbert-Lepoutre, A.

    2013-09-01

    Jupiter Trojans are asteroids trapped into the L4 and L5 Lagrangian clouds of the Jupiter-Sun system. Their origin is still a matter of debate, and their study could bring a critical test between different models of the solar system dynamical evolution. Trojans could have formed where they are, in which case they could bring crucial clues on the formation of Jupiter itself [1, 2]. It is not clear however, how this primordial population of Trojans could have survived the great shaking suggested in the Grand Tack model [3]. The Nice model indicates that Trojans might have been supplied from the outer parts of the solar system [4], in which case they could highlight the properties of their far less accessible parents, the Kuiper Belt Objects. Understanding the composition of Trojans could thus put strong constraints on the conditions (temperature, pressure and chemical composition) prevailing at the time and place of their formation. In particular, models of the solar system dynamical evolution suggest that Trojans had a cometary part. As of today, a large observational effort has provided spectra, which are very similar to spectra of cometary dust [4, 5, 6, 7, 8, 9, 10, 11, 12]. Their low albedos and surface colors are also consistent to those of comets [13]. Their rotation period distribution indicates a possible past outgassing [14]. Although Trojans can be regarded as dead or dormant comets, no water ice has ever been reported, nor any coma ever detected. In this work, we investigate the possibility for Jupiter Trojans to maintain water ice in subsurface layers, using a 3D thermal evolution model. The influence of several parameters, like the albedo, the obliquity, the rotation period, or the thermal inertia, are studied. The survival of water ice is tested against sublimation, and bulk heating due to the decay of radioactive nuclides.

  1. Dynamics of Binary Near-Earth Asteroid System (35107) 1991 VH

    NASA Astrophysics Data System (ADS)

    Naidu, Shantanu P.; Margot, J. L.; Busch, M. W.; Taylor, P. A.; Nolan, M. C.; Howell, E. S.; Giorgini, J. D.; Benner, L. A. M.; Brozovic, M.; Magri, C.

    2012-05-01

    Near-Earth Asteroid (35107) 1991 VH was discovered to be a binary in March 1997, based on its light-curve (IAUC 6607). It made a very close approach to the Earth in August 2008 at a distance of 0.045 AU. We used this opportunity to secure an extensive radar data set with the Arecibo S-band (2380 MHz, 13 cm wavelength) planetary radar system, including range-Doppler images with spatial resolution as fine as 15 m. The images (spanning 14 days) reveal that the primary is roughly spheroidal with a radius of 650 m. The range extent of the secondary in these images varies from less than 100 m to more than 200 m indicating that it is highly elongated. The radar data provide an excellent determination of the mutual orbit: The orbital period is 32 hours, the eccentricity is 0.05, and the total system mass is 1.5e12 kg. Numerical simulations of the spin of the elongated secondary in this eccentric mutual orbit reveal a large region of chaos in the phase space, similar to that observed in Saturn’s moon Hyperion (Wisdom, Peale, Mignard 1984). The chaotic region surrounds the 1:2, 1:1, 3:2 and 2:1 spin-orbit resonances, but allows for islands of stability around the 1:2 and 1:1 spin-orbit states. The secondary’s echo bandwidths indicate that its spin rate indeed lies within or very close to this chaotic region. To date no acceptable fit to the sequence of secondary images has been found under the assumption of synchronous spin. Saturn’s moon Hyperion is the only solar system object known so far to have a chaotic spin state (Wisdom, Peale, Mignard 1984).

  2. 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.

  3. 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.

  4. 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.

  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. Sub-populations among the Jupiter Trojans

    NASA Astrophysics Data System (ADS)

    Wong, I.; Brown, M.

    2014-07-01

    The Jupiter Trojans are a significant population of minor bodies in the middle Solar System. Lying in a 1:1 mean-motion resonance with Jupiter and concentrated in two swarms centered about the L4 and L5 Lagrangian points, their peculiar location and dynamical properties place the Trojans at the intersection of several of the most important topics in planetary science. The origin and evolution of this population have been a subject of particular interest. While earlier theories proposed a scenario in which the Trojans formed at the same heliocentric distance as Jupiter, a recent theory, known as the Nice model, suggests a more complex picture in which the Trojan population originated in a region beyond the primordial orbit of Neptune. Through interactions with neighboring planetesimals, the gas giants underwent a rapid migration, setting off a period of chaotic dynamical alterations in the outer Solar System. It is hypothesized that during this time, the primordial transneptunian 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 study of the nature of the Trojans may shed light on the relationships between the Trojans and other minor body populations in the outer Solar System, and more broadly, crucially constrain models of late Solar System evolution. Several past spectroscopic studies of Trojans have revealed notable bimodalities with respect to near-infrared spectra, infrared albedo, and color, which point toward the existence of two distinct groups among the Trojan population. In our work, we have carried out an analysis of the magnitude distributions of these two groups, which we refer to as the red and less-red color populations. By compiling spectral data from previous works and photometric data from the Sloan Digital Sky Survey, we show that the

  8. Spectroscopy and Photometry of Mars Trojans

    NASA Technical Reports Server (NTRS)

    Rivkin, A. S.; Binzel, R. P.; Howell, E. S.; Bus, S. J.; Grier, J. A.

    2003-01-01

    Mars is the only terrestrial planet known to have co-orbiting Trojan asteroids. We have obtained visible and near-IR reflectance spectra of three of these objects: 5261 Eureka and 1998 VF31 in the L5 region and 1999 UJ7 in the LA region. We also obtained JHK spectrophotometry and a visible lightcurve for 5261 Eureka. The asteroid 5261 Eureka has a visible spectrum that is classified as Sr in the Bus taxonomy, and has infrared colors consistent with the A-class asteroids. The data for 1998 VF31 have a restricted wavelength range, but are most consistent with the Sr or Sa class, though we note a marginal consistency with the D class. We can rule out a C-class classification. 1999 UJ7 has an X-class or T-class spectrum, which is unlike that of the other two Mars Trojans. The photometric data for Eureka are limited, but we can constrain the period to longer than 5 hours (likely 5.5-6 hours) and lightcurve amplitude of at least 0.15 magnitude at this viewing geometry. The spectral differences among the Mars Trojans suggests that either they did not all form at their present solar distances or that they have not always been at their present sizes.

  9. 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.

  10. 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

  11. 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.

  12. Arecibo and Goldstone Radar Observations of Binary Near-Earth Asteroid and Marco Polo-R Mission Target (175706) 1996 FG3

    NASA Astrophysics Data System (ADS)

    Benner, L. A. M.; Brozovic, M.; Giorgini, J. D.; Lawrence, K. J.; Taylor, P. A.; Nolan, M. C.; Howell, E. S.; Busch, M. W.; Margot, J. L.; Naidu, S. P.; Magri, C.; Shepard, M. K.

    2012-05-01

    We report Arecibo (2380 MHz), 13-cm) and Goldstone (8560 MHz, 3.5-cm) delay-Doppler radar observations of binary near-Earth asteroid and Marco Polo-R mission target (175706) 1996 FG3 that were obtained on nine dates November-December, 2011.

  13. 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

  14. Stability and Evolution of Orbits around Binary Asteroids: Applications to the Marco Polo Mission Scenario

    NASA Astrophysics Data System (ADS)

    Wickhusen, K.; Oberst, J.; Hussmann, H.; Shi, X.; Damme, F.

    2011-10-01

    We have analyzed the orbit stability of a spacecraft moving around a small Near-Earth-Asteroid (NEA), focusing on the primary target of the Marco Polo Mission: 175706 (1996 FG3). The simulation showed that most orbits are unstable over time but under certain conditions the S/C stays in orbit without crashing or escaping into space.

  15. On habitable Trojan worlds in exoplanetary systems

    NASA Astrophysics Data System (ADS)

    Schwarz, Richard; Eggl, Siegfried; Akos, Bazso; Funk, Barbara

    2016-09-01

    When astronomers look for life on planets in exoplanetary systems (EPS), they use the concept of the habitable zone (HZ) for the search of life in the universe. In many EPS a giant planet moves in the HZ and makes the existence of another habitable planet impossible, because of the gravitational interaction with a gas giant (GG). Therefore the investigation of the Trojan configuration provides another opportunity for an additional habitable planet. The configuration is the following, when a GG (like Jupiter or larger) moves in the HZ, a terrestrial Trojan planet may move in a stable orbit around the Lagrangian equilibrium points L4 or L5. Trojans are moving either close to 60° ahead or 60° behind the GG with nearly the same semi-major axis as the planet (as shown in the figure for the circular case). Former studies (Schwarz et al. 2009 and Schwarz et al 2014) could show that this configuration is not only stable for small bodies like asteroids (e.g. Jupiter Trojans), but also for larger ones (Earth-mass). We investigate the stability of possible Trojan planets in several known extra-solar planetary systems, by using the planar 3 and N-body problem as dynamical model considering the eccentricity of the planets. For our numerical simulations we use the Lie-integration method with an automatic step-size control to solve the equations of motion (Eggl and Dvorak 2010). In our study, we have concentrated on the extension of the stability region around the Lagrangian points and the influence of additional outer or inner GG. Finally we present a list of candidates of EPS where a massive GG (3-10 Jupiter masses) moves almost or fully in the HZ and an additional possible Trojan planet can have stable motion.

  16. On the stability of the Neptune Trojans

    NASA Astrophysics Data System (ADS)

    Dvorak, R.; Schwarz, R.; Süli, Á.; Kotoulas, T.

    2007-12-01

    The area of stable motion for fictitious Trojan asteroids around Neptune's equilateral equilibrium points is investigated with respect to the size of the regions and their shape, subject to the inclination of the asteroid's orbit. For this task, we used the results of extensive numerical integrations of orbits for a fine grid in initial conditions around the points L4 and L5 and analysed the stability of the individual orbits. Our basic dynamical model was the outer Solar system (Jupiter, Saturn, Uranus and Neptune) but for comparison reasons also simpler ones were tested. We integrated in our models the equations of motion for some 5 × 105 orbits of fictitious Trojans in the vicinity of the stable equilibrium points up to 109 yr. According to the three-dimensional model, the initial inclination of the asteroids' orbit was also varied in the range 0° < i < 60°. Using on one side a fine grid of initial conditions, the semimajor axis versus perihelion of the fictitious object and, on the other side, the proper eccentricity ep versus the libration width Df, we compiled stability maps separately for L4 and L5. In addition, we computed the escape-times of the individual objects and plotted the number of escapers per time-interval of 5 × 106 yr for different initial inclinations. Finally, integrations of the equations of motion in different dynamical models shed light on the reason of the asymmetry of the stability behaviour of orbits close to the two equilateral equilibrium points of Neptune. For low-inclined Trojan orbits, the stability area around L4 and L5 disappeared after some 108 yr, and for larger inclinations of the Trojans the stability area survived for the time-interval of integration of 109yr. The largest stable regions exist for Neptune Trojans with 20° < i < 50°. The somewhat interesting asymmetry in the size and the shape of the preceding and following Lagrange points, which exist for Neptune Trojans, was confirmed, and was found to be caused mostly

  17. 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

  18. 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

  19. 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.

  20. 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.

  1. How different are the Greeks from the Trojans?

    NASA Astrophysics Data System (ADS)

    Chatelain, J. P.; Henry, T.; Scott, N.; Winters, J.

    2011-10-01

    The Greek and Trojan camps situated at the stable L4 and L5 Lagrangian points of Jupiter are two largely unexamined populations of asteroids that could provide vital clues to the formation and evolution of the solar system. A close examination of the differences and similarities between the camps could hint at the mechanisms responsible for their precarious placement as well as the primordial conditions of the early Solar System within which they formed. Also, their position at Jupiter's orbit means that they are an ideal intermediate population between the inner Main Belt asteroids and the asteroids in the outer Solar System.

  2. Spectrophotometric study of asteroids

    NASA Technical Reports Server (NTRS)

    Chapman, C. R.

    1974-01-01

    Observations of particular faint asteroids of interest, in particular the Trojans, were carried out during an observation run at Kitt Peak National Observatory (1.3 meter telescope) in September 1973, and an attempt was made to study the compositional variation within Hirayama families. A particularly important study was initiated to observe spectrophotometrically certain asteroids which are considered as potential source bodies for meteorites. A program was also undertaken to coordinate the spectrophotometry program with polarimetric and thermal-infrared observation programs being conducted elsewhere.

  3. 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.

  4. 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

  5. Ejecta cloud from the AIDA space project kinetic impact on the secondary of a binary asteroid: I. mechanical environment and dynamical model

    NASA Astrophysics Data System (ADS)

    Yu, Yang; Michel, Patrick; Schwartz, Stephen R.; Naidu, Shantanu P.; Benner, Lance A. M.

    2017-01-01

    An understanding of the post-impact dynamics of ejecta clouds are crucial to the planning of a kinetic impact mission to an asteroid, and also has great implications for the history of planetary formation. The purpose of this article is to track the evolution of ejecta produced by AIDA mission, which targets for kinetic impact the secondary of near-Earth binary asteroid (65803) Didymos on 2022, and to feedback essential informations to AIDA's ongoing phase-A study. We present a detailed dynamic model for the simulation of an ejecta cloud from a binary asteroid that synthesizes all relevant forces based on a previous analysis of the mechanical environment. We apply our method to gain insight into the expected response of Didymos to the AIDA impact, including the subsequent evolution of debris and dust. The crater scaling relations from laboratory experiments are employed to approximate the distributions of ejecta mass and launching speed. The size distribution of fragments is modeled with a power law fitted from observations of real asteroid surface. A full-scale demonstration is simulated using parameters specified by the mission. We report the results of the simulation, which include the computed spread of the ejecta cloud and the recorded history of ejecta accretion and escape. The violent period of the ejecta evolution is found to be short, and is followed by a stage where the remaining ejecta is gradually cleared. Solar radiation pressure proves to be efficient in cleaning dust-size ejecta, and the simulation results after two weeks shows that large debris on polar orbits (perpendicular to the binary orbital plane) has a survival advantage over smaller ejecta and ejecta that keeps to low latitudes.

  6. 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

  7. 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

  8. 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.

  9. 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

  10. 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.

  11. Mutual Orbits, Size, Density, and Interior of Visualized Multiple Asteroids

    NASA Astrophysics Data System (ADS)

    Marchis, F.; Vachier, F.; Durech, J.; Berthier, J.; Hanus, J.

    2012-12-01

    Since 2001 our team collected Adaptive Optics Observations of high-size ratio multiple asteroids (e.g. 22 Kalliope, 130 Elektra, 624 Hektor) and large similarly-sized binary asteroids (90 Antiope, 617 Patroclus) using 8-10m class telescopes such as Gemini North, VLT-UT4, and W.M. Keck II telescopes and archive data from HST. Using a new genetic-based algorithm, named GENOID (Vachier et al. 2012), we derived the orbital parameters of ~16 multiple asteroids, including 13 main-belt asteroids, 2 Jupiter-trojan asteroids and one Transneptunian asteroid. This efficient algorithm allows us to explore a wide range or orbital solutions without any a priori constrain on the system. Two types of dynamical models, one purely Keplerian and a dynamical one (which fits as well the size and J2/J4 of the primary) can be used. In the last case, we can also infer the distribution of material in the primary. The volume of these asteroids is derived by combining mid-IR observations from Spitzer/IRS, IRAS, WISE or AKARI with lightcurve inversion technique and stellar occultations. The bulk density derived for these asteroids confirmed a relationship between their taxonomic classes and their composition with an average density of ~3.5 g/cc for M-type asteroids, ~1 g/cc for C/P/D-type and ~2 g/cc for S-type. We will present an overview of our analysis emphasizing the most recent results in particular the size, shape and internal structure of (624) Hektor. We will also discuss new directions of investigations using more performant AO systems soon available on 8-10m class telescopes. More accessible multi-user campaigns to observe stellar occultation and also mutual event between the components of the systems aiming at refining the size & shape of the primary and the size of the satellite(s) will be described. GENOID algorithm provides orbital solution directly implemented in the IMCCE ephemerides allowing the predictions of these events and the position of the satellite(s).

  12. 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.

  13. 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.

  14. Low and high albedo jovian Trojans and Hildas: a similar or different origin?

    NASA Astrophysics Data System (ADS)

    Marsset, M.; Vernazza, P.; Gourgeot, F.; Dumas, C.; Birlan, M.; Lamy, P.; Binzel, R. P.

    2014-04-01

    Jupiter Trojans and Hilda asteroids are small primitive bodies located near or beyond the snow line, around respectively the L4 and L5 Lagrange points of Jupiter at ~5.2AU from the sun (Trojans) and in the 2:3 mean-motion resonance with Jupiter near 3.9AU (Hildas). Our current understanding of the early dynamical evolution of the Solar System tells us that they probably originated from the primordial transneptunian region from which they were captured in their current location (Nice model; [6, 5]). In addition, this region not only comprised planetesimals formed beyond the snow line (D-, T- and X-type asteroids) but also a minor population of rocky interlopers (e.g., A-, S-, V-type asteroids) that migrated outward during the very early evolutionary phases of the Solar System 5 to 7My after its formation (Grand Tack model; [8]). The recent discovery by WISE [2, 3] and Spitzer [1] of high albedo (pv ≥0.15) asteroids within jovian Trojans and Hildas opened the possibility of an observational evidence for the presence of a small fraction (~2 %) of such interlopers among these two low albedo (pv ∼0.07) populations. Here, we report the very first spectroscopic characterization of a sample of high albedo tTrojans and Hildas obtained with X-SHOOTER and SpeX in the visible and / or nearinfrared ranges. This study allows us to investigate the origin of these high albedo objects and to provide an estimate of the contamination rate of jovian Trojans and Hilda asteroids by objects that do not belong to the C / T / D-type complex (e.g., A-, S-, V-type asteroids), thus constraining migration models [7, 4, 6, 5, 8]. The results of this study will be presented in details.

  15. 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.

  16. 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

  17. 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

  18. 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.

  19. 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."

  20. 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

  1. Arecibo and Goldstone Radar Observations of Binary Near-Earth Asteroid and Marco Polo-R Mission Target (175706) 1996 FG3

    NASA Astrophysics Data System (ADS)

    Benner, Lance A. M.; Brozovic, M.; Giorgini, J. D.; Lawrence, K. J.; Taylor, P. A.; Nolan, M. C.; Howell, E. S.; Busch, M. W.; Margot, J.; Naidu, S. P.; Magri, C.; Shepard, M. K.

    2012-10-01

    We report Arecibo (2380 MHz), 13-cm) and Goldstone (8560 MHz, 3.5-cm) delay-Doppler radar observations of binary near-Earth asteroid and Marco Polo-R mission target (175706) 1996 FG3 that were obtained on nine dates between November 6-December 17, 2011. The images achieve resolutions as fine as 75 m in range and place hundreds of pixels on the primary. The images provide thorough rotational coverage by the primary and reveal a rounded, slightly elongated object with a visible extent of 0.9 km. If the visible extent is about ½ of the actual extent, which would be true for a sphere, then the equatorial diameter is about 1.8 km. The primary has features along its leading edge that resemble the signature of the pronounced ridge on the equator of binary asteroid (66391) 1999 KW4. The images sample a wide range of orbital positions by the secondary, resolve it in range and Doppler frequency, show that it is elongated and roughly 500 m in diameter, and suggest that its rotation is synchronous (or nearly so) with the orbital period of 16.1 h estimated by Scheirich and Pravec (2009, Icarus 200, 531-547). We observe a maximum range separation of 2.5 km that, combined with the nearly circular eccentricity found by Scheirich and Pravec from inversion of lightcurves, establishes a lower bound on the semimajor axis. 1996 FG3 has a circular polarization ratio SC/OC = 0.34±0.02 that is comparable to that of 25143 Itokawa (0.28±0.04), suggesting similar degrees of near-surface roughness. The radar data will yield a 3D model of the primary, possibly a coarse-resolution model of the secondary, more precise orbit fitting, and estimates of the system’s mass and bulk density.

  2. 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.

  3. Asteroid Lightcurve Derived Data V16.0

    NASA Astrophysics Data System (ADS)

    Harris, A. W.; Warner, B. D.; Pravec, P.

    2016-10-01

    This is a compilation of published rotational parameters derived from lightcurve data for asteroids, based on the Warner et al. (2009) Asteroid Lightcurve Database. This is the version as of February 16, 2016. In addition to reported rotational parameters by individual paper, there is a summary file with the values adopted by Harris, Warner, and Pravec as the most likely correct values for each asteroid. The data set also contains files listing known binary asteroids, asteroid spin axes, and 'tumbling' asteroids.

  4. Asteroid Lightcurve Derived Data V15.0

    NASA Astrophysics Data System (ADS)

    Harris, A. W.; Warner, B. D.; Pravec, P.

    2015-12-01

    This is a compilation of published rotational parameters derived from lightcurve data for asteroids, based on the Warner et al. (2009) Asteroid Lightcurve Database. This is the version as of February 6, 2015. In addition to reported rotational parameters by individual paper, there is a summary file with the values adopted by Harris, Warner, and Pravec as the most likely correct values for each asteroid. The data set also contains files listing known binary asteroids, asteroid spin axes, and 'tumbling' asteroids.

  5. Asteroid Lightcurve Analysis at Elephant Head Observatory: 2012 November - 2013 April

    NASA Astrophysics Data System (ADS)

    Alkema, Michael S.

    2013-07-01

    Thirteen asteroids were observed from Elephant Head Observatory from 2012 November to 2013 April: the main-belt asteroids 227 Philosophia, 331 Etheridgea, 577 Rhea, 644 Cosima, 850 Altona, 906 Repsolda, 964 Subamara, 973 Aralia, 1016 Anitra, 1024 Hale, 2034 Bernoulli, 2556 Louise, and Jupiter Trojan 3063 Makhaon.

  6. 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.

  7. 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

  8. A New Surface Density Model of Jovian Trojans around Triangular Libration Points

    NASA Astrophysics Data System (ADS)

    Nakamura, Tsuko; Yoshida, Fumi

    2008-04-01

    We constructed a new surface number density distribution model for Jovian Trojans around the L4 or L5 libration point of Jupiter. This is an empirical asymmetric model of the Maxwellian-Gaussian type, derived from numerical integrations of orbital motions for actual Trojan asteroids around the L4 point. With this model, in combination with the observed surface number densities obtained by Yoshida and Nakamura (2005, AJ, 130, 2900; 2008, PASJ, 60, 297), we estimate that the total populations of L4 and L5 Trojans with diameters (D)>2km are (6.3±1.0)×104 and (3.4±0.5) ×104, respectively. These results indicate that the L4 total populations (D> 2km) calculated previously by Jewitt, Trujillo, and Luu (2000, AJ, 120, 1140) and by Yoshida and Nakamura (2005, ibid.) using the former's isotropic Gaussian model are overestimated by a factor of 3-4.

  9. 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.

  10. 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

  11. 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

  12. 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.

  13. 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.

  14. Giga-year evolution of Jupiter Trojans and the asymmetry problem

    NASA Astrophysics Data System (ADS)

    Di Sisto, Romina P.; Ramos, Ximena S.; Beaugé, Cristián

    2014-11-01

    We present a series of numerical integrations of observed and fictitious Jupiter Trojan asteroids, under the gravitational effects of the four outer planets, for time-spans comparable with the age of the Solar System. From these results we calculate the escape rate from each Lagrange point, and construct dynamical maps of "permanence" time in different regions of the phase space. Fictitious asteroids in L4 and L5 show no significant difference, showing almost identical dynamical maps and escape rates. For real Trojans, however, we found that approximately 23% of the members of the leading swarm escaped after 4.5 Gyrs, while this number increased to 28.3% for L5 . This implies that the asymmetry between the two populations increases with time, indicating that it may have been smaller at the time of formation/capture of these asteroids. Nevertheless, the difference in chaotic diffusion cannot, in itself, account for the current observed asymmetry (∼40%), and must be primarily primordial and characteristic of the capture mechanism of the Trojans. Finally, we calculate new proper elements for all the numbered Trojans using the semi-analytical approach of Beaugé and Roig (Beaugé, C., Roig, F.V. [2001]. Icarus, 153, 391-415), and compare the results with the numerical estimations by Brož and Rosehnal (Brož, M., Rosehnal, J. [2011]. Mon. Not. R. Astron. Soc. 414, 565-574). For asteroids that were already numbered in 2011, both methods yield very similar results, while significant differences were found for those bodies that became numbered after 2011.

  15. 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

  16. Tidal torques on infrequently colliding particle disks in binary systems and the truncation of the asteroid belt

    NASA Technical Reports Server (NTRS)

    Franklin, F. A.; Lecar, M.; Lin, D. N. C.; Papaloizou, J.

    1980-01-01

    Conditions leading to the truncation, at the 2:1 resonance, of a disk of infrequently colliding particles surrounding the primary of a binary system are studied numerically and analytically. Attention is given to the case in which the mass ratio, q, is sufficiently small (less than about 0.1) and the radius of the disk centered on the primary allowably larger, so that first-order orbit-orbit resonances between ring material and the secondary can lie within it. Collisions are found to be less frequent than q to the -2/3 power orbital periods (the period of the forced eccentricity at the 2:1 resonance), and truncation occurs and Kirkwood gaps are produced only if the particle eccentricity is less than some critical value, estimated to be of order q to the 5/9 power, or approximately 0.02 for the sun-Jupiter case having q equal to 10 to the -3rd power.

  17. Asteroid families

    NASA Astrophysics Data System (ADS)

    Nesvorný, David; Bottke, William F.; Vokrouhlický, David; Morbidelli, Alessandro; Jedicke, Robert

    An asteroid family is a group of asteroids with similar orbits and spectra that was produced by a collisional breakup of a large parent body. To identify asteroid families, researchers look for clusters of asteroid positions in the space of proper orbital elements. These elements, being more constant over time than osculating orbital elements, provide a dynamical criterion of whether a group of bodies has a common ancestor. More than fifty asteroid families have been identified to date. Their analysis produced several important insights into the physics of large scale collisions, dynamical processes affecting small bodies in the Solar System, and surface and interior properties of asteroids.

  18. Sample return from asteroids --- Hayabusa2 and the next

    NASA Astrophysics Data System (ADS)

    Yoshikawa, M.; Kuninaka, H.; Inaba, N.; Tsuda, Y.; Watanabe, S.; Mori, O.; Yano, H.; Nakamura, R.; Kawaguchi, J.

    2014-07-01

    In 2006, a few years before the Earth return of Hayabusa, which is the first asteroid sample-return mission in the world, we started to consider the next asteroid sample-return mission, Hayabusa2. Hayabusa was a mission for engineering, but Hayabusa2 focuses also on the science. The scientific purpose of Hayabusa2 is to learn about the origin and evolution of the solar system, especially, the origin of water and organic matters. It is considered that C-type asteroids contain more organic matters and hydrated minerals than S-type asteroids like Itokawa. Therefore, the C-type asteroid (162173) 1999 JU_3 was selected as the target. From the technological point of view, the purpose of Hayabusa2 is to make a more reliable and robust system for sample-return exploration. The scale of the spacecraft is similar to Hayabusa, but many parts are modified so that we will not have to face the trouble that we experienced in Hayabusa. We will try new things, too. One of them is the impactor, which creates a small crater on the surface of the asteroid. Then, we can sample the sub-surface material as shown in the figure. We are now preparing the spacecraft for launch at the end of 2014. Hayabusa2 will arrive at the asteroid in June 2018. It will stay there for about one and half years. Then, it will leave the asteroid in December 2019, and will come back to the Earth in December 2020 [1]. We have already started to consider the next sample-return mission after Hayabusa2. In this future mission, the target asteroid is a Jupiter Trojan, which is a more primitive asteroid (D/P-type asteroid) than the S-type Itokawa and C-type 1999 JU_3. We use the solar-power-sail technique, which was demonstrated successfully by IKAROS. IKAROS means Interplanetary Kite-craft Accelerated by Radiation Of the Sun, and it was the first interplanetary solar sail in the world. The science purpose of this Jupiter Trojan mission is to study the various kinds of issues related to the planetary formation, such

  19. 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.

  20. Searching for Solar System Wide Binaries with Pan-STARRS-1

    NASA Astrophysics Data System (ADS)

    Holman, Matthew J.; Protopapas, P.; Tholen, D. J.

    2007-10-01

    Roughly 60% of the observing time of the Pan-STARRS-1 (PS1) telescope will be dedicated to a "3pi steradian" survey with an observing cadence that is designed for the detection of near-Earth asteroids and slow-moving solar system bodies. Over this course of its 3.5 year cience mission, this unprecedented survey will discover nearly every asteroid, Trojan, Centaur, long-period comet, short-period comet, and trans-neptunian object (TNO) brighter than magnitude R=23. This census will be used to address a large number of questions regarding the physical and dynamical properties of the various small body populations of the solar system. Roughly 1-2% of TNOs are wide binaries with companions at separations greater than 1 arcsec and brightness differences less than 2 magnitudes (Kern & Elliot 2006; Noll et al 2007). These can be readily detected by PS1; we will carry out such a search with PS1 data. To do so, we will modify the Pan-STARRS Moving Object Processing System (MOPS) such that it will associate the components of resolved or marginally resolved binaries, link such pairs of detections obtained at different epochs, and the estimate the relative orbit of the binary. We will also determine the efficiency with which such binaries are detected as a function of the binary's relative orbit and the relative magnitudes of the components. Based on an estimated 7000 TNOs that PS1 will discover, we anticipate finding 70-140 wide binaries. The PS1 data, 60 epochs over three years, is naturally suited to determining the orbits of these objects. Our search will accurately determine the binary fraction for a variety of subclasses of TNOs.

  1. 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…

  2. Asteroid Densities

    NASA Astrophysics Data System (ADS)

    Britt, D. T.; Yeomans, D.; Housen, K.; Consolmagno, G.

    2005-01-01

    This data set contains a tabulation of asteroid masses, diameters, and bulk densities compiled by D. T. Britt and published in Table 1 of Britt, et al. (2002) [BRITTETAL2002] in the 'Asteroids III' volume.

  3. 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.

  4. 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

  5. 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.

  6. Discovery of Slow Rotators in The Jovian Trojan Population from Pan-STARRS Medium Deep Fields

    NASA Astrophysics Data System (ADS)

    Cheng, Y.; Ip, W.; Lin, H.; Chen, Y.; Chen, W.

    2013-12-01

    Pan-STARRS 1 (PS1) project is the largest optical sky survey project in the current time-domain astronomy. It provides a wealth of high-cadence and high quality data for the study of solar system small bodies like asteroids and the trans-Neptunian objects. We analyzed four of the PS1 Medium Deep (MD) fields around the elliptic plane and developed a new method to determine the rotation curves and surface colors of solar system objects in those dataset. The basic concept of our method is the merge of all photometric data separated in four PS1 filters (g, r, i, z) in order to improve the time coverage of measurements available for each object. We used the predicted brightness as a standard in each epoch and calculated the difference between the apparent brightness and predicted magnitude (Δm). The Δm values of individual filter pairs can then be used to shift all of the brightness data points to the same baseline to obtain a unified time-series lightcurve and determine the brightness variation and the corresponding amplitude, sometimes even the rotation periods. In this manner, we found five slow rotators with rotation periods longer than 10 days among the 92 Jovian Trojans we have examined. Four of these slow rotators, (7543), (216421), (248978) and (343993), have large rotation amplitudes and are possibly contact binary systems. The surface colors of three of these five slow rotators belong to the C-type taxonomic class which is unusual in the L4 population.

  7. 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?

  8. 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

  9. Dynamics of single and multiple asteroids based on Gaia observations

    NASA Astrophysics Data System (ADS)

    Hestroffer, D.

    2014-07-01

    The Gaia mission from the European Space Agency (ESA) has been launched in December 2013, and is currently under commissioning phase. Gaia is expected to provide huge improvements in the science of Solar System Objects (SSO) [1]. Indeed, depending on the actual limiting magnitude that will be achieved by the telescope (mag. V<20 nominally) about 300,000 asteroids will be observed (mostly known). These include near-Earth objects (NEOs), main-belt bodies, Trojans, as well as bright Centaurs and transneptunian objects (TNOs), and, moreover, several comets and a few planetary satellites. The Gaia telescope will regularly scan the sky during its 5 years operation, down to the solar elongation of 45°, providing one of the largest systematic surveys of such bodies. The observation and data reduction for Solar System Objects is specifically included in the data-reduction pipeline, and the final Gaia catalogue will contain very important data for planetary science. After resuming the general aspects of Gaia observations of SSOs, and some of their limitations, we will focus on the astrometric information, dynamics, orbit determination, and improvements that can be performed on asteroids. The direct outcome from Gaia astrometric measurements (orbit improvement, binary-asteroid and multiple-system orbits, mass and bulk density determination for a significant number of large asteroids, local test of general relativity, detection of non-gravitational effects, etc.) will be presented, as well as their link to imaging and photometric measurements (size, shape, spin rate and spin direction, albedo, taxonomy, etc.). A ground-based network Gaia-FUN-SSO dedicated to the follow-up of critical objects such as newly discovered NEOs has been set up. Detection of new objects, computation of orbits, and ground- based follow-up will also be addressed. At the end of its mission, Gaia will provide a much broader view of the dynamical and physical characteristics of the Small Bodies of the

  10. 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.

  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. 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.

  14. Stability and Evolution of Orbits Around the Binary Asteroid 175706 (1996 FG3) and Asteroids 162173 (1999 JU3) and 101955 (1999 RQ36): Implications for the MARCO-POLO-R Mission

    NASA Astrophysics Data System (ADS)

    Hussmann, H.; Oberst, J.; Wickhusen, K.; Shi, X.; Damme, F.; Luedicke, F.; Lupovka, V.; Bauer, S.

    2012-05-01

    In support of the Marco-Polo-R mission, we have carried out numerical simulations of spacecraft trajectories searching for stable orbits about the asteroids 175706(1996 FG3), 1999 RQ36 and 1999 JU3 under the influence of solar radiation pressure.

  15. 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.

  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. 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.

  18. 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.

  19. Towards Countering the Rise of the Silicon Trojan

    DTIC Science & Technology

    The Trojan Horse has a venerable if unwelcome history and it is still regarded by many as the primary component in Computer Network Attack. Trojans ... Trojans have in the vast majority taken the form of malicious software. However, more recent times have seen the emergence of what has been dubbed by some...as the ’Silicon Trojan ’ these trojans are embedded at the hardware level and can be designed directly into chips and devices. The complexity of the

  20. 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.

  1. Where are the Saturnian Trojans?

    NASA Astrophysics Data System (ADS)

    Innanen, K. A.; Mikkola, S.

    1988-01-01

    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. Such orbits show no sign of instability, for at least a million years. For Saturn the existence of such orbits is surprising because of the periodic proximity of Jupiter. The authors discuss the results of their numerical study, and consider the possibilities of observational confirmation of their conclusions. There is preliminary evidence for similar stability for the Trojan analogues of the inner planets.

  2. 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.

  3. 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.

  4. Binary Minor Planets

    NASA Astrophysics Data System (ADS)

    Richardson, Derek C.; Walsh, Kevin J.

    2006-05-01

    A review of observations and theories regarding binary asteroids and binary trans-Neptunian objects [collectively, binary minor planets (BMPs)] is presented. To date, these objects have been discovered using a combination of direct imaging, lightcurve analysis, and radar. They are found throughout the Solar System, and present a challenge for theorists modeling their formation in the context of Solar System evolution. The most promising models invoke rotational disruption for the smallest, shortest-lived objects (the asteroids nearest to Earth), consistent with the observed fast rotation of these bodies; impacts for the larger, longer-lived asteroids in the main belt, consistent with the range of size ratios of their components and slower rotation rates; and mutual capture for the distant, icy, trans-Neptunian objects, consistent with their large component separations and near-equal sizes. Numerical simulations have successfully reproduced key features of the binaries in the first two categories; the third remains to be investigated in detail.

  5. 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.

  6. Space weathering and the color-color diagram of Plutinos and Jupiter Trojans

    NASA Astrophysics Data System (ADS)

    Melita, M. D.; Kaňuchová, Z.; Brunetto, R.; Strazzulla, G.

    2015-03-01

    The Jupiter Trojan asteroids and the Plutinos are two peculiar populations. They are dynamically resonant, therefore with heliocentric distances relatively bounded for long timescales, as a farely general rule. As a consequence, some correlation with the surface color properties of their respective members is expected. Indeed, there are apparent differences in the B - V vs. V - R color-color diagram of the two populations. Using a simple model based on the surface color due to the contribution of two components, one pristine and one altered, we find as plausible that the difference is due to the interplay of space weathering by energetic cosmic-radiation and collisional effects.

  7. 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.

  8. Creating and Transporting Trojan Wave Packets

    NASA Astrophysics Data System (ADS)

    Wyker, B.; Ye, S.; Dunning, F. B.; Yoshida, S.; Reinhold, C. O.; Burgdörfer, J.

    2012-01-01

    Nondispersive localized Trojan wave packets with ni˜305 moving in near-circular Bohr-like orbits are created and transported to localized near-circular Trojan states of higher n, nf˜600, by driving with a linearly polarized sinusoidal electric field whose period is slowly increased. The protocol is remarkably efficient with over 80% of the initial atoms being transferred to the higher n states, a result confirmed by classical trajectory Monte Carlo simulations.

  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. Characterizing the Neptune Trojan Orbit Distribution

    NASA Astrophysics Data System (ADS)

    Parker, Alex H.

    2013-10-01

    The Neptune Trojan swarms are large, stable minor planet populations, and their orbit distribution encodes information about Neptune's late-stage migration and the properties of the planetesimal disk that Neptune encountered. However, extracting a meaningful model of the Neptune Trojans' orbit distribution is made difficult by the uncharacterized biases present in the very small observed sample. I will describe a survey-agnostic statistical method for quantifying the range of plausible orbit distribution models for the Neptune Trojans, using priors gleaned from other resonant minor planet populations, and present quantitative limits on the orbital properties of Neptune Trojans. I will also discuss the results of a suite of Neptune Trojan capture simulations designed to explore the implications of their measured present-day orbital properties; I find that migrating Neptune into a pre-heated disk is required to reproduce the inclinations seen in the extant Trojans, and that capture efficiency remains high even as disk excitation increases. This indicates that some process was responsible for pre-heating the planetesimal disk prior to Neptune's arrival, such as an earlier epoch of interactions with a giant planet.

  11. Debris about asteroids: Where and how much?

    NASA Technical Reports Server (NTRS)

    Burns, Joseph A.; Hamilton, Douglas P.

    1992-01-01

    We summarize several recent findings on the size and shape of the region within which material can stably orbit an asteroid. If the asteroid (with assumed density 2.38 g/cu cm) circles the Sun at 2.55 AU, co-planar prograde material will remain trapped whenever started on unperturbed circular orbits at less than about 220 R(sub A) (asteroid radii); co-planar retrograde particles are stable out twice as far. Our 3-D stability surface, which encloses several hundred numerically calculated orbits that start with various inclinations, is shaped like a sphere with its top and bottom sliced off; its dimensions scale like the Hill radius =(mu/3)(exp 1/3)R, where mu is the asteroid-to-solar mass ratio and R is the asteroid's orbital radius. If the asteroid moves along an elliptical orbit, a fairly reliable indicator of the dimensions of the hazard zone is the size of its Hill sphere at the orbit's pericenter. Grains with radii less than a few mm will be lost through the action of radiation forces which can induce escape or cause collisions with the asteroid on times scales of a few years; interplanetary micrometeoroids produce collisional break-up of these particles in approximately 10(exp 4) yrs. The effects of Jupiter and of asteroids that pass close to the target asteroid allow particles to diffuse from the system, again shrinking the hazard zone. None of the considered sources-primordial formation, debris spalled off the asteroid during micrometeoroid impact, captured interplanetary particles, feeder satellites, etc., seem capable of densely populating distant orbits from the asteroid. No certain detections of debris clouds or of binary asteroids have been made. Thus, it seems highly unlikely that a spacecraft fly-by targeted at 100 R(sub A) from the asteroid over its orbital pole would encounter any material.

  12. 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.

  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. 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.

  15. 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

  16. 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.

  17. International CJMT-1 Workshop on Asteroidal Science

    NASA Astrophysics Data System (ADS)

    Ip, Wing-Huen

    2014-03-01

    An international workshop on asteroidal science was held between October 16 and 17, 2012, at the Macau University of Science and Technology gathering together experts on asteroidal study in China, Japan, Macao and Taiwan. For this reason, we have called it CJMT-1 Workshop. Though small in sizes, the asteroids orbiting mainly between the orbit of Mars and of Jupiter have important influence on the evolution of the planetary bodies. Topics ranging from killer asteroids to space resources are frequently mentioned in news reports with prominence similar to the search for water on Mars. This also means that the study of asteroids is very useful in exciting the imagination and interest in science of the general public. Several Asian countries have therefore developed long-term programs integrating ground-based observations and space exploration with Japan being the most advanced and ambitious as demonstrated by the very successful Hayabusa mission to asteroid 25143 Itokawa. In this volume we will find descriptions of the mission planning of Hayabusa II to the C-type near-Earth asteroid, 1999 JU3. Not to be outdone, China's Chang-E 2 spacecraft was re-routed to a flyby encounter with asteroid 4179 Toutatis in December 2012. It is planned that in the next CJMT workshop, we will have the opportunity to learn more about the in-depth data analysis of the Toutatis observations and the progress reports on the Hayabusa II mission which launch date is set to be July 2014. Last but not least, the presentations on the ground-based facilities as described in this volume will pave the way for coordinated observations of asteroidal families and Trojan asteroids - across Asia from Taiwan to Uzbekistan. Such international projects will serve as an important symbol of good will and peaceful cooperation among the key members of this group. Finally, I want to thank the Space Science Institute, Macao University of Science and Technology, for generous support, and its staff members

  18. Asteroid Impact and Deflection Assessment mission: the Double Asteroid Redirection Test (DART)

    NASA Astrophysics Data System (ADS)

    Cheng, A.; Michel, P.

    2015-10-01

    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, which includes the ESA Asteroid Impact Mission (AIM) rendezvous spacecraft 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 6.5 km/s and demonstrate the ability to modify its trajectory through momentum transfer. The primary goals of AIDA are (i) to investigate the binary near-Earth asteroid (65803) Didymos, (ii) to demonstrate asteroid deflection by kinetic impact and to characterize the deflection. The primary DART objectives are to demonstrate a hypervelocity 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.

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. Capture of Trojans by Jumping Jupiter

    NASA Astrophysics Data System (ADS)

    Nesvorný, David; Vokrouhlický, 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 ~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) × 10-7 for each particle in the original transplanetary disk, implying that the disk contained (3-4) × 107 planetesimals with absolute magnitude H < 9 (corresponding to diameter D = 80 km for a 7% albedo). The disk mass inferred from this work, M disk ~ 14-28 M Earth, is consistent with the mass deduced from recent dynamical simulations of the planetary instability.

  8. 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.

  9. (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

  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. A Unified Submodular Framework for Multimodal IC Trojan Detection

    NASA Astrophysics Data System (ADS)

    Koushanfar, Farinaz; Mirhoseini, Azalia; Alkabani, Yousra

    This paper presents a unified formal framework for integrated circuits (IC) Trojan detection that can simultaneously employ multiple noninvasive measurement types. Hardware Trojans refer to modifications, alterations, or insertions to the original IC for adversarial purposes. The new framework formally defines the IC Trojan detection for each measurement type as an optimization problem and discusses the complexity. A formulation of the problem that is applicable to a large class of Trojan detection problems and is submodular is devised. Based on the objective function properties, an efficient Trojan detection method with strong approximation and optimality guarantees is introduced. Signal processing methods for calibrating the impact of inter-chip and intra-chip correlations are presented. We propose a number of methods for combining the detections of the different measurement types. Experimental evaluations on benchmark designs reveal the low-overhead and effectiveness of the new Trojan detection framework and provides a comparison of different detection combining methods.

  12. Radar images of asteroid 1989 PB

    NASA Astrophysics Data System (ADS)

    Ostro, S. J.; Chandler, J. F.; Hine, A. A.; Rosema, K. D.; Shapiro, I. I.; Yeomans, D. K.

    1990-06-01

    Radar observations of the near-earth asteroid 1989 PB, made shortly after its optical discovery, yield a sequence of delay-Doppler images that reveal it to consist of two distinct lobes that appear to be in contact. It seems likely that the two lobes once were separate and that they collided to produce the current 'contact-binary' configuration.

  13. 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.

  14. 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...

  15. On enigmatic properties of the main belt asteroids

    NASA Astrophysics Data System (ADS)

    Kochemasov, G.

    two warping waves cannot be inscribed in a sphere otherwise than to stretch a body in one direction and to press it in the perpendicular one. Thus, an enigmatic shape of Mars is explained by this way. Asteroids are subjected to a warping action of the wave that bulges one hemisphere and presses the opposite one making convexo-concave bean shape [1]. This wave resonate (1 to 1) with the fundamental wave causing dichotomy of all celestial bodies . This very strong resonance enhances a warping action. That is why asteroids are flat, oblong and bean-shaped. The bulging hemisphere is always cracked, and this cracking sometimes is so strong that "saddles" appear sometimes cutting body into two or more pieces (binaries, satellites). Eros and the small Trojan satellite of Saturn Calypso (PIA07633) are very similar in this typical shape (convexo-concave shape and a "saddle") though they have different compositions, sizes and strengths. It was 1 shown earlier that degassing and rotations of terrestrial planets may be tied by redistribution of their angular momentum between a solid body and its gaseous envelope [2]. Bodies with higher orb. fr. and thus more finely granulated (Mercury, Venus) are more thoroughly wiped out of its volatiles and rotate slower because a significant part of their momenta gone with atmosphere (The Mercury's atmosphere was destroyed by the solar wind). The main asteroid belt rather stretched (2.2-3.2 a.u.) is composed of metallic, stone and carbonaceous bodies (judging by spectra and meteorites) , the first two dominating its inner part, the third -the outer one (similarity with the inner planets in respect of volatiles distribution). Less degassed asteroids keeping their original mass and "original" momentum (i.e.,the larger bodies) differ from the smaller ones having lost their original mass by degassing and spalling and shared their momenta with gone off parts. That is why the larger bodies are fast, the smaller ones slow rotating. References: [1

  16. Albedos of Centaurs, Jovian Trojans and Hildas

    NASA Astrophysics Data System (ADS)

    Romanishin, William

    2017-01-01

    I present optical V band albedo distributions for samples of outer solar system minor bodies including Centaurs, Jovian Trojans and Hildas. Diameters come almost entirely from the NEOWISE catalog (Mainzer etal 2016- Planetary Data System). Optical photometry (H values) for about 2/3 of the approximately 2700 objects studied are from PanStarrrs (Veres et al 2015 Icarus 261, 34). The PanStarrs optical photometry is supplemented by H values from JPL Horizons (corrected to be on the same photometric system as the PanStarrs data) for the objects in the NEOWISE catalog that are not in the PanStarrs catalog. I compare the albedo distributions of various pairs of subsamples using the nonparametric Wilcoxon rank sum test. Examples of potentially interesting comparisons include: (1) the median L5 Trojan cloud albedo is about 10% darker than that of the L4 cloud at a high level of statistical significance and (2) the median albedo of the gray Centaurs lies between that of the L4 and L5 Trojan groups.

  17. 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.

  18. 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

  19. Leucocyte protein Trojan, a possible regulator of apoptosis.

    PubMed

    Petrov, Petar; Syrjänen, Riikka; Uchida, Tatsuya; Vainio, Olli

    2017-02-01

    Trojan is a leucocyte-specific protein, cloned from chicken embryonic thymocyte cDNA library. The molecule is a type I transmembrane protein with an extracellular CCP domain, followed by two FN3 domains. Its cytoplasmic tail is predicted to possess a MAPK docking and a PKA phosphorylation sites. Trojan has been proposed to have an anti-apoptotic role based on its differential expression on developing thymocyte subpopulations. Using a chicken cell line, our in vitro studies showed that upon apoptosis induction, Trojan expression rises dramatically on the surface of surviving cells and gradually decreases towards its normal levels as cells recover. When sorted based on their expression levels of Trojan, cells with high expression appeared less susceptible to apoptotic induction than those bearing no or low levels of Trojan on their surface. The mechanism by which the molecule exerts its function is yet to be discovered. We found that cells overexpressing Trojan from a cDNA plasmid show elevated steady-state levels of intracellular calcium, suggesting the molecule is able to transmit cytoplasmic signals. The mechanistic nature of Trojan-induced signalling is a target of future investigation. In this article, we conducted a series of experiments that suggest Trojan as an anti-apoptotic regulator.

  20. 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

  1. 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.

  2. 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

  3. Direct Detection of the Asteroidal YORP Effect

    NASA Astrophysics Data System (ADS)

    Lowry, Stephen C.; Fitzsimmons, A.; Pravec, P.; Vokrouhlicky, D.; Boehnhardt, H.; Taylor, P. A.; Margot, J. L.; Galád, A.; Irwin, M.; Irwin, J.; Kusnirák, P.

    2007-10-01

    The Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect is a torque that can modify the rotation rates and obliquities of small bodies in the solar system via the combined effects of incident solar radiation pressure and the recoil effect from anisotropic emission of thermal photons. The YORP effect is the only realistic mechanism for explaining the intriguing spin-axis alignments within the Koronis asteroid family, and quite possibly explains the anomalous distribution of spin rates for small asteroids. YORP is now thought to be an important mechanism in the formation of binary asteroid systems, and has a direct bearing on the related Yarkovsky effect, which affects the orbital motion of small asteroids. Despite its importance, there exists only indirect evidence for the presence of YORP on solar system objects, until now. We conducted an optical-imaging monitoring campaign from 2001-2005 on a small near-Earth asteroid, 2000 PH5, now known as asteroid (54509) YORP. We found that the asteroid has been continuously increasing its sidereal rotation rate by (2.0 ± 0.2)*10-4 deg./day2, over this 4-yr period (Lowry et al., 2007, Science 316, 272-274). The observed YORP strength is consistent with detailed shape-model-based theoretical calculations of the effect (Taylor et al., 2007, Science 316, 274-277). We simulated the asteroid's close Earth approaches from 2001 to 2005, showing that gravitational torques cannot explain the observed spin rate increase. Dynamical simulations suggest that 2000 PH5 may reach a rotation period of just 20 seconds toward the end of its expected lifetime.

  4. Asteroid sizes and albedos

    NASA Technical Reports Server (NTRS)

    Morrison, D.

    1977-01-01

    The radiometric method of determining asteroid diameters is described, and a synthesis of radiometric and polarimetric measurements of the diameters and geometric albedos of a total of 187 asteroids is presented. An analysis is offered of the size distributions of different albedo classes down to 80-km diameter for the entire main asteroid belt (2.0-3.5 AU). The distribution of albedos is found to be strongly bimodal, with mean albedos for the C and S group of 0.035 and 0.15, respectively. The C asteroids outnumber the S asteroids at all sizes and all values of semimajor axis, with the proportion of C asteroids increasing from a little over half inside 2.5 AU to more than 95% beyond 3.0 AU. Other aspects of the distribution of C, S, and M asteroids are discussed, and the total mass of main-belt asteroids larger than 70 km is estimated.

  5. Observational data and orbits of the asteroids discovered at the Molėtai observatory in 2008-2009

    NASA Astrophysics Data System (ADS)

    Černis, K.; Wlodarczyk, I.; Zdanavičius, J.

    We present the statistics of the asteroids observed and discovered at the Molėtai Observatory, Lithuania, in 2008-2009 within the project for astrometric observations of the near-Earth objects (NEOs), the main belt asteroids and comets. CCD observations of the asteroids were obtained with the 35/51-cm Maksutov-type meniscus telescope. In the Minor Planet Circulars and the Minor Planet Electronic Circulars (2008-2009), 11 900 astrometric positions of 2522 asteroids were published. Among them 95 were new asteroids, including four belonging to the Trojan group: (352655) 2008QX28, 2008 SE8, (353194) 2009 SM100 and (264068) 2009 SQ148. For the asteroids discovered at Molėtai their precise orbits are calculated. Because of short observational arc, a few asteroids have low-precision orbits and some asteroids are considered lost. For the three Main Belt asteroids with low-precision orbital elements, 2008 QP32, 2008 SD8 and 2008 SG150, we present their ephemerides for 2017. They can be brighter than 20 mag.

  6. 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...

  7. The Trojan Horse Method in nuclear astrophysics

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    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.

  8. 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

  9. 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.

  10. 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 simulations with

  11. 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.

  12. Exotic orbits of asteroids in the solar system and their impacts on space missions

    NASA Astrophysics Data System (ADS)

    Schwarz, Richard

    2017-01-01

    Speaking of exotic orbits we mean objects in co-orbital motion. Objects in co-orbital motion are two celestial bodies moving in the same orbit or similar distance to the central body then they are in the so called 1:1 mean motion resonance (MMR). There are several configurations of co-orbital objects, depending on their point of libration: 1. The satellite configuration. 2. A common configuration in our Solar System especially for asteroids is the so-called Trojans. These are two groups of asteroids moving close to the equilibrium points (Lagrangian points) L4 and L5 in a 1:1 mean motion resonance with Jupiter (also with Earth, Mars, Uranus and Neptune). That means that Jupiter's Trojans are moving either close to 60° ahead respectively 60° behind the Jupiter with the same semi-major axis as the planet. 3. Similar class to the Trojan class is the horseshoe orbits, in which objects librates around 180° from the planet. 4. Another exotic class of orbits is the exchange orbit that occurs when two co-orbital objects are of similar masses and thus exert a non-negligible influence on each other. The objects can exchange semi-major axes (e.g. Saturnian moons Janus and Epimetheus) or eccentricities when they approach each other. After the success of space missions like SOHO and Herschel-Plank the scientific interest increased towards to the benefit of the Lagrangian points and other exotic motions.

  13. Asteroid lightcurve inversion

    NASA Technical Reports Server (NTRS)

    Ostro, Steven J.; Connelly, Robert

    1987-01-01

    One of the most fundamental physical properties of any asteroid is its shape. Lightcurves provide the only source of shape information for most asteroids. Unfortunately, the functional form of a lightcurve is determined by the viewing/illumination geometry and the asteroid's light scattering characteristics as well as its shape, and in general it is impossible to determine an asteroid's shape from lightcurves. A technique called convex-profile inversion (CPI) that obtains a convex profile, P, from any lightcurve is introduced. If certain ideal conditions are satisfied, then P is an estimator for the asteroid's mean cross section, C, a convex set defined as the average of all cross sections C(z) cut by planes a distance z above the asteroids's equatorial plane. C is therefore a 2-D average of the asteroid's 3-D shape.

  14. Study of 2003 YT1 Asteroid

    NASA Astrophysics Data System (ADS)

    Vodniza, A. Q.; Rojas, M.

    2011-10-01

    The asteroid 2003 YT1 was at approximately 25 million kilometers from the Earth on May 05-2011 (U.T) [1]. It has an orbital period of 1.17 years and it was estimated to have a size of 2.63 kilometers [2]. 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 [3]. 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. This asteroid has a rotation period of 2.343 hours [4] and its binary nature was noted by the Modra and Ondrejov Observatories independently [5]. Nolan used radar observations to determine that this is a binary with sizes of approximately 1 and 0.2 km and primary rotation period of P < 2.6 h [6]. The asteroid will be at approximately 0.0348 A.U from the Earth on October 31-2016 and at approximately 0.0113 A.U from the Earth on October 31-2016 [7]. Astrometry was carried out, and we calculated the orbital elements. It was designed a computing program on Visual Basic 6.0. SPACEWEATHER published our video of 2003YT1 on May 5/2011 [8].

  15. Saturn Trojans: a dynamical point of view

    NASA Astrophysics Data System (ADS)

    Hou, X. Y.; Scheeres, D. J.; Liu, L.

    2014-01-01

    Different from the usual approach in the inertial frame, the stability problem of fictitious Saturn Trojans is studied in the synodic frame in this paper. First, some numerical facts are shown to allow us to simplify the force model. Then, motion equations centred at the geometrical triangular libration points for the planar S-JS model are derived. Using these equations, the resonance mechanism that causes the instability is studied. We confirm the opinion that the secular resonances and the near-commensurability between the libration frequency and the great inequality are the reasons to cause the instability of motions close to the triangular libration point. By studying the survivability of the long period family and the short period family in the S-JSUN model, the planar stable region far away from the triangular libration point is studied. By frequency analysis of the orbits in the stable region, we are able to find two secular resonances associated with the boundary of the stable region. Three-dimensional motion is also discussed, by starting with the survivability of the vertical period family in the S-JSUN model. The secular resonance that causes the orbit inclination restriction on the Trojans is qualitatively discussed. Lastly, the effects of planetary migrations are briefly studied. With the contribution in this paper, a global picture of the dynamics around the triangular libration points in the Sun-Saturn system perturbed by Jupiter is presented.

  16. 5 - 14 μm Spitzer spectra of primitive asteroid families

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

    Compositional studies of primitive asteroid families provide constraints on the physical and chemical environment of the solar nebula and the evolution of the asteroid belt. Spectroscopic studies in the visible and near-infrared have shown spectral diversity between primitive families. Our goal is 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 a total of 18 asteroids, nine from each family. We report the presence of a broad 10-μm emission feature, attributed to a layer of fine-grained silicates, in the spectra of all nine 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 geometric albedos in the range 0.06 ± 0.01 to 0.14 ± 0.02. 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 suggest icy bodies with some amount of fine-grained silicates, but with coarser grains or denser surface structure than Trojan asteroids and comets.

  17. Testing the inversion of Gaia photometry of asteroids

    NASA Astrophysics Data System (ADS)

    Santana-Ros, Toni; Bartczak, Przemysław; Michałowski, Tadeusz; Tanga, Paolo; Cellino, Alberto

    2016-06-01

    We studied the performance of the Gaia inversion algorithm under different scenarios. The test consisted of feeding the algorithm with several sets of photometric simulations for ten thousand asteroids having different spin axis orientations, rotational periods and shapes, including binaries. We used the Gaia mission simulator to generate the observational epochs, while the brightnesses were generated using a Z-buffer standard graphic method. It was found that results are biased against asteroids presenting low lightcurve amplitude and low pole latitudes. The analysis of the inversion results led to the confirmation that synchronous binary systems can be successfully modelled with a simple triaxial ellipsoid body. On the basis of these simulations, it was also possible to develop strategies for binary asteroid detection. The presented quantitative results include the semi-major axis values of the triaxial ellipsoid model with a high probability of hosting binary systems. We also present the Gaia-Groundbased Observation Service for Asteroids (Gaia-GOSA), which aims to support ground-based observation campaigns of asteroids.

  18. Beam-energy dependence and updated test of the Trojan-horse nucleus invariance via a measurement of the 2H(d ,p )3H reaction at low energies

    NASA Astrophysics Data System (ADS)

    Li, Chengbo; Wen, Qungang; Tumino, A.; Fu, Yuanyong; Zhou, Jing; Zhou, Shuhua; Meng, Qiuying; Spitaleri, C.; Pizzone, R. G.; Lamia, L.

    2017-03-01

    The 2H(d ,p )3H bare nucleus astrophysical S (E ) factor has been measured indirectly at energies from about 500 keV down to several keV by means of the Trojan-horse method applied to the 2H(6Li,p t )4He quasifree reaction induced at 11 MeV. The obtained results are compared with direct data as well as with previous indirect investigation of the same binary reactions. It shows that the precision of S (E ) data in the low-energy range extracted via the same Trojan-horse nuclei [6Li=(d ⊕α )] becomes better when the incident energy of the virtual binary process decreases from high value down to the lower Gamow energy range, which near the zero-quasi-free-energy point. The very good agreement between data extracted from different Trojan-horse nuclei [6Li=(d ⊕α ) vs 3He=(d ⊕p )] gives a strong updated test for the independence of the binary indirect cross section on the chosen Trojan-horse nucleus at low energies.

  19. 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

  20. 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

  1. 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)

  2. 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

  3. 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.

  4. The asteroids. [review

    NASA Technical Reports Server (NTRS)

    Chapman, C. R.; Hartmann, W. K.; Williams, J. G.

    1978-01-01

    The asteroids are small rocky bodies that orbit in modestly eccentric and inclined orbits, mainly between the orbits of Mars and Jupiter. With the comets, they are the only known population of residual planetesimals from the earliest epochs of solar system history. The observational characteristics of asteroids are discussed, taking into account aspects of photometry, rotations, masses and densities, spectrophotometry and surface compositions, surface textures and regoliths, size distribution, and erosion and fragmentation occurring as a result of interasteroidal collisions. Questions of dynamics and orbital evolution are investigated and ramifications for planetary evolution are explored. Attention is given to asteroids as planetesimals, aspects of early orbital evolution, the geochemical evolution of asteroids, commensurabilities and Kirkwood gaps, secular resonances, the material transport from the asteroid belt, Poisson's theorem, planetary masses, catalogs and selection effects, families, and Apollo, Amor, and Mars-crossing asteroids.

  5. 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

  6. 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.

  7. Physical properties of asteroids

    NASA Technical Reports Server (NTRS)

    Veeder, Glenn J.

    1988-01-01

    Infrared photometry at 1.2, 1.6 and 2.2 micrometer provides a relatively rapid and accurate method for the classification of asteroids and is important for comparison with laboratory measurements of meteorites and other possible compositional analogues. Extension beyond the visual is espicially useful for minerals which have strong characteristic infrared colors such as olivine in the A class asteroids. Radiometry at long infrared wavelengths is important for deriving basic physical parameters (via thermal models) such as size and albedo which in turn enables the conversion of relative colors to absolute reflectances. In particular, albedos are the only way to distinguish among the otherwise ambiguous E, M and P classes of asteroids. Infrared observations of 15 asteroids were made at the NASA infrared Telescope Facility (IRTF) on Mauna Kea in 1987. Researchers completed the analysis of 22 Aten, Apollo and Amor asteroids. Results include albedos and diameters for these objects as well as the identification of the first known class M and Class E near-Earth asteroids. The standard thermal model appears to be inadequate for some of these small asteroids because of their coarse regolith, so researchers constructed a rotating thermal model for such asteroids. They have identified a subtle systematic difference between the sub-populations of large and small IRAS asteroids as well as several anomalous objects.

  8. Asteroid and comet surfaces

    NASA Technical Reports Server (NTRS)

    Mcfadden, Lucy-Ann

    1988-01-01

    Photometric and spectrophotometric studies of asteroids and comets are in progress to address questions about the mineralogical relationship between asteroids near the 3:1 Kirkwood gap and ordinary chondrite meteorites and between cometary nuclei and the surface of asteroids. Progress was made on a method to convert the measured excess UV flux in the spectrum of 2201 Oljato to column abundance of OH and CN. Spectral reflectance measurements of large asteroids near the 3:1 Kirkwood gap, which is expected to be the source of ordinary chondrite meteorites, were briefly examined and show no spectral signatures that are characteristic of ordinary chondrite meteorite powders measured in the lab.

  9. Radar investigation of asteroids

    NASA Technical Reports Server (NTRS)

    Ostro, S. J.

    1981-01-01

    Software to support all stages of asteroid radar observation and data analysis is developed. First-order analysis of all data in hand is complete. Estimates of radar cross sections, circular polarization ratios, and limb-to-limb echo spectral bandwidths for asteroids 7 Iris, 16 Psyche, 97 Klotho, 1862 Apollo, and 1915 Quetzalcoatl are reported. Radar observations of two previously unobserved asteroids were conducted. An Aten asteroid, 2100 Ra-Shalom, with the smallest known semimajor axis (0.83) was detected. Preliminary data reduction indicates a circular polarization ratio comparable to those of Apollo, Quetzalcoatl, and Toro.

  10. Radar investigation of asteroids

    NASA Astrophysics Data System (ADS)

    Ostro, S. J.

    1981-11-01

    Software to support all stages of asteroid radar observation and data analysis is developed. First-order analysis of all data in hand is complete. Estimates of radar cross sections, circular polarization ratios, and limb-to-limb echo spectral bandwidths for asteroids 7 Iris, 16 Psyche, 97 Klotho, 1862 Apollo, and 1915 Quetzalcoatl are reported. Radar observations of two previously unobserved asteroids were conducted. An Aten asteroid, 2100 Ra-Shalom, with the smallest known semimajor axis (0.83) was detected. Preliminary data reduction indicates a circular polarization ratio comparable to those of Apollo, Quetzalcoatl, and Toro.

  11. Speckle interferometry of asteroids

    NASA Technical Reports Server (NTRS)

    Drummond, Jack

    1988-01-01

    This final report for NASA Contract NAGw-867 consists of abstracts of the first three papers in a series of four appearing in Icarus that were funded by the preceding contract NAGw-224: (1) Speckle Interferometry of Asteroids I. 433 Eros; (2) Speckle Interferometry of Asteroids II. 532 Herculina; (3) Speckle Interferometry of Asteroids III. 511 Davida and its Photometry; and the fourth abstract attributed to NAGw-867, (4) Speckle Interferometry of Asteroids IV. Reconstructed images of 4 Vesta; and a review of the results from the asteroid interferometry program at Steward Observatory prepared for the Asteroids II book, (5) Speckle Interferometry of Asteroids. Two papers on asteroids, indirectly related to speckle interferometry, were written in part under NAGw-867. One is in press and its abstract is included here: Photometric Geodesy of Main-Belt Asteroids. II. Analysis of Lightcurves for Poles, Periods and Shapes; and the other paper, Triaxial Ellipsoid Dimensions and Rotational Pole of 2 Pallas from Two Stellar Occultations, is included in full.

  12. 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.

  13. 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.

  14. Reliability of Physical Systems: Detection of Malicious Subcircuits (Trojan Circuits) in Sequential Circuits

    NASA Astrophysics Data System (ADS)

    Matrosova, A. Yu.; Kirienko, I. E.; Tomkov, V. V.; Miryutov, A. A.

    2016-12-01

    Reliability of physical systems is provided by reliability of their parts including logical ones. Insertion of malicious subcircuits that can destroy logical circuit or cause leakage of confidential information from a system necessitates the detection of such subcircuits followed by their masking if possible. We suggest a method of finding a set of sequential circuit nodes in which Trojan Circuits can be inserted. The method is based on random estimations of controllability and observability of combinational nodes calculated using a description of sequential circuit working area and an evidence of existence of a transfer sequence for the proper set of internal states without finding the sequence itself. The method allows cutting calculations using operations on Reduced Ordered Binary Decision Diagrams (ROBDDs) that can depend only on the state variables of the circuit. The approach, unlike traditional ones, does not require preliminary sequential circuit simulation but can use its results. It can be used when malicious circuits cannot be detected during sequential circuit verification.

  15. The Color-Magnitude Distribution of Small Jupiter Trojans

    NASA Astrophysics Data System (ADS)

    Wong, Ian; Brown, Michael E.

    2015-12-01

    We present an analysis of survey observations targeting the leading L4 Jupiter Trojan cloud near opposition using the wide-field Suprime-Cam CCD camera on the 8.2 m Subaru Telescope. The survey covered about 38 deg2 of sky and imaged 147 fields spread across a wide region of the L4 cloud. Each field was imaged in both the g‧ and the i‧ band, allowing for the measurement of g - i color. We detected 557 Trojans in the observed fields, ranging in absolute magnitude from H = 10.0 to H = 20.3. We fit the total magnitude distribution to a broken power law and show that the power-law slope rolls over from 0.45 ± 0.05 to {0.36}-0.09+0.05 at a break magnitude of {H}b={14.93}-0.88+0.73. Combining the best-fit magnitude distribution of faint objects from our survey with an analysis of the magnitude distribution of bright objects listed in the Minor Planet Center catalog, we obtain the absolute magnitude distribution of Trojans over the entire range from H = 7.2 to H = 16.4. We show that the g - i color of Trojans decreases with increasing magnitude. In the context of the less-red and red color populations, as classified in Wong et al. using photometric and spectroscopic data, we demonstrate that the observed trend in color for the faint Trojans is consistent with the expected trend derived from extrapolation of the best-fit color population magnitude distributions for bright cataloged Trojans. This indicates a steady increase in the relative number of less-red objects with decreasing size. Finally, we interpret our results using collisional modeling and propose several hypotheses for the color evolution of the Jupiter Trojan population. Based on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

  16. Serendipitous Observations of Asteroids by the K2 Mission

    NASA Astrophysics Data System (ADS)

    Barentsen, Geert

    2015-11-01

    The K2 mission is using the unique assets of the Kepler space telescope to perform long-baseline, high-cadence, high-precision photometry of targets selected by the community. Unlike the original Kepler mission, the loss of two reaction wheels requires K2 to point near the ecliptic plane. As a result, thousands of faint asteroids can be seen to pass through the target pixel masks that are downlinked to earth after each ~75-day observing campaign. I will show how these serendipitous observations of asteroids can be used to obtain lightcurves for faint (V>18) objects which are otherwise challenging to target from the ground. In particular, I will demonstrate that the data are well-suited to identify small asteroids with rotation periods near or below the ~2 hour "spin barrier". I will also highlight the K2 data of other solar system bodies, including the comets, trans-Neptunian objects and Jupiter trojans for which dedicated pixel masks have been (or will be) downlinked. Owing to its ecliptic pointing and 1.4-meter diameter mirror, K2 is offering unique time-series photometry of small solar system bodies at a precision which is unlikely to be rivaled by the future, smaller-aperture photometric missions such as TESS and PLATO.

  17. 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

  18. 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)

  19. 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

  20. 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.

  1. Revealing Secrets of Triple Asteroid Systems with SPHERE

    NASA Astrophysics Data System (ADS)

    Yang, Bin; Wahhaj, Zahed; Beauvalet, Laurene; Marchis, Franck; Dumas, Christophe; Marsset, Michaël

    2015-11-01

    A multiple-asteroid system provides otherwise unattainable information about the intrinsic properties of the system itself as well as its formation and evolution. Comparative spectroscopy and imaging of two large multiple main-belt asteroids: (93) Minerva and (130) Elektra were performed using the newly commissioned Spectro-Polarimetric High-contrast Exoplanet Research instrument (SPHERE) on ESO's 8.2-m VLT. A new moon (S/2014 (130) 1), of the known binary asteroid (130) Elektra, was discovered based on the SPHERE observations, making (130) Elektra the sixth triple system detected in the asteroid belt. We will present the component-resolved near infrared spectra, from 0.9 to 1.6 micron, of the Minerva and the Elektra triple systems. We will also present the orbital solution and the dynamical simulations on the two moons of (130) Elektra.

  2. Near-Sun asteroids

    NASA Astrophysics Data System (ADS)

    Emel'yanenko, V. V.

    2017-01-01

    As follows from dynamical studies, in the course of evolution, most near-Earth objects reach orbits with small perihelion distances. Changes of the asteroids in the vicinity of the Sun should play a key role in forming the physical properties, size distribution, and dynamical features of the near-Earth objects. Only seven of the discovered asteroids are currently moving along orbits with perihelion distances q < 0.1 AU. However, due to the Kozai-Lidov secular perturbations, the asteroids, having recently passed near the Sun, could by now have moved to orbits farther from the Sun. In this study, we found asteroids that have been recently orbiting with perihelion distances q < 0.1 AU. Asteroids may be on such orbits for hundreds to tens of thousands of years. To carry out astrophysical observations of such objects is a high priority.

  3. Speckle interferometry applied to asteroids and other solar system objects

    NASA Technical Reports Server (NTRS)

    Drummond, J. D.; Hege, E. K.

    1986-01-01

    Speckle interferometry is a high angular resolution technique that allows study of resolved asteroids. By following the changing size, shape, and orientation of minor planets, and with a few general assumptions (e.g., geometric scattering, triaxial ellipsoid figures, no albedo features), it is possible to directly measure an asteroid's true dimensions and the direction of its spin axis in one or two nights. A particular subset of triaxial ellipsoid figures are equilibrium shapes, and would imply that some asteroids are thoroughly fractured. Such shapes if they exist among the asteroids would allow a determination of bulk density since there is a unique relation among spin period, size, shape, and density. The discovery of even a single rubble pile, (just as the finding of even one binary asteroid by speckle interferometric techniques) would drastically alter the notion of asteroids as small solid planets. The Pluto/Charon system was studied to aid in improving the orbital elements necessary to predict the eclipse/occultation season currently in progress. Four asteroids were reduced to their size, shape, and pole direction: 433 Eros, 532 Herculina, 511 Davida, and 2 Pallas.

  4. Galahad: medium class asteroid sample return mission

    NASA Astrophysics Data System (ADS)

    Cheng, Andrew; Rivkin, Andrew; Adler, Mark

    The Galahad asteroid sample return mission proposal to the NASA New Frontiers solicitation met all of the objectives for the Asteroid Rover/Sample Return mission as defined in that announcement. Galahad is in many ways similar to the Marco Polo and the OSIRIS-Rex proposals. All three missions plan bulk sample returns from primitive, C or B class Near Earth asteroids. Galahad in particular will rendezvous with and orbit the binary C-asteroid 1996 FG3, making extensive orbital measurements. It will then land and collect over 60 g of well-documented samples with geologic context for return to Earth. The samples are expected to provide abundant materials from the early solar system, including chondrules and CAIs, as well as a primitive assemblage of organics, presolar grains and probably hydrated minerals. Analyses of these samples will yield new understanding of the early solar system, planetary accretion, and the nature and origins of prebiotic organic material. We will discuss scientific and technical approaches to characterization of, landing on, and sample collection from small primitive bodies.

  5. On the dynamical habitability of Trojan planets in exoplanetary systems

    NASA Astrophysics Data System (ADS)

    Schwarz, R.; Funk, B.; Bazsó, Á.; Eggl, S.

    2017-03-01

    Besides the hierarchical configurations exoplanets have been observed in so far, Earth-analogs can theoretically exist in co-orbital motion with giant planets. Those so-called Trojan planets share the same orbit as their Jovian hosts, trailing or leading by approximately 60 degrees in mean anomaly. If a giant planet was situated in the habitable zone (HZ) of an exoplanetary system coorbital terrestrial worlds could in principle also be habitable provided their orbits are "tame enough". In this paper, we study the dynamical properties of Earth-like Trojan planets in their host stars' respective HZs. We investigate the orbital stability of possible Trojan planets near the Lagrangian equilibrium points L_4 and L_5 for several candidate systems. Our numerical simulations have been carried out using the planar three-body problem, in case the extrasolar system contains only one known planet and the n-body problem with more than one planet in the system. We study the stability region around the equilibrium points and counted the number of stable orbits concentrating on the dependencies between the semimajor axis, the eccentricity and the argument of perihelion of the Trojan planet. We found that of the investigated 14 systems 6 support stable Trojan planets in the system's HZ, namely HD 5891, HD 28185, WASP-41, HD 11755, HD 221287 and HD 13908.

  6. The eight-color asteroid survey - Results for 589 minor planets

    NASA Astrophysics Data System (ADS)

    Zellner, B.; Tholen, D. J.; Tedesco, E. F.

    1985-03-01

    Results are presented from reflection spectrophotometry of 589 minor planets in a photometric system using eight filter passbands ranging from 0.34- to 1.04-micron wavelength. The sampling completeness approaches or exceeds 50 percent of the numbered asteroids for the near-earth objects, the Hungarias, the Nysa family, the Cybeles, the Hildas, and the Trojans. The general evolution of predominant compositional type from S to C to D with increasing heliocentric distance is evident, as is the spectral homogeneity of the Eos, Koronis, Nysa, and Themis families.

  7. 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

  8. Morphological Evolution of Asteroids

    NASA Astrophysics Data System (ADS)

    Richardson, D. C.

    2003-08-01

    Recent ground- and space-based observations of asteroids have revealed that these bodies are far more complex than once imagined. Surprisingly low bulk densities, giant craters, unusual shapes, non-principal-axis spin states, and satellites are all challenging our understanding of how asteroids form and evolve. Since asteroids are the remnants of the planet building era, understanding their nature improves our understanding of the origin of solar systems in general. I will review some of the more puzzling aspects of asteroid morphology, including the existence of asteroid satellites, and discuss recent theoretical advances aimed at understanding our tiny neighbors. I will show that both theoretical and observational evidence is pointing increasingly to asteroids being fragile assemblages of smaller pieces, called gravitational aggregates. The consequences of such fragmented internal structure on asteroid evolution and hazard mitigation will be discussed. This work has been supported in part by the National Aeronautics and Space Administration under Contract No. NAG511722 issued through the Office of Space Science.

  9. Samples from Asteroid Itokawa

    NASA Astrophysics Data System (ADS)

    Taylor, G. J.; Martel, L. M. V.

    2011-08-01

    The Hayabusa spacecraft, flown by the Japanese Aerospace Exploration Agency (JAXA), returned samples from asteroid 25143 Itokawa on June 13, 2010. Though the sampling device did not operate properly, the mission was able to return a couple thousand particles, from a few- to a few hundred-micrometers across. A battery of laboratory analyses (electron microscopy, elemental analysis, and oxygen isotopic measurements) shows that the particles derive from materials like those in thermally metamorphosed LL group ordinary chondrites. Astronomical observations had classified Itokawa as a stony S(IV) type of asteroid. The nature of S-type asteroids has been debated for decades; some astronomers argued that S-type asteroids are ordinary chondrites while others suggested that they were more likely to be differentiated objects (i.e., melted or partially melted to make igneous rocks). The problem was that we did not know enough about space weathering on asteroids to know how the spectra of chondritic or differentiated asteroids changed with exposure to micrometeorites and solar wind. The examinations of Hayabusa's treasure have settled the argument: S-type asteroid, Itokawa, indeed has an ordinary chondrite composition whose spectrum has been reddened by space weathering. This conclusion is supported by detailed studies of the surfaces of 10 Itokawa particles, half of which have glassy rims (5-50 nanometers thick) containing nano-sized particles of iron sulfide and metallic iron, signatures of space weathering. Analysis of noble gases in three particles from the asteroid indicate that they were exposed on the surface of Itokawa for surprisingly short times, less than 8 million years. The Hayabusa science team suggests that the short exposure time indicates loss of particles into space through small impacts at the surprisingly fast rate of tens of centimeters per million years. This might not seem fast, but the asteroid, only 535 x 294 x 209 meters in size, would become just a

  10. 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

  11. 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.

  12. 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.

  13. Radar Investigations of Asteroids

    NASA Technical Reports Server (NTRS)

    Ostro, S. J.

    1984-01-01

    Radar investigations of asteroids, including observations during 1984 to 1985 of at least 8 potential targets and continued analyses of radar data obtained during 1980 to 1984 for 30 other asteroids is proposed. The primary scientific objectives include estimation of echo strength, polarization, spectral shape, spectral bandwidth, and Doppler shift. These measurements yield estimates of target size, shape, and spin vector; place constraints on topography, morphology, density, and composition of the planetary surface; yield refined estimates of target orbital parameters; and reveals the presence of asteroidal satellites.

  14. Where Did Ceres Accrete - In Situ in the Asteroid Belt, Among the Giant Planets, or in the Primordial Transneptunian Belt?

    NASA Astrophysics Data System (ADS)

    McKinnon, William B.

    2012-10-01

    Ceres appears to be in rotational hydrostatic equilibrium and its density implies a substantial water ice fraction (20±5% by mass). Thermal evolution arguments strongly favor an icy outer shell as opposed to bound water throughout (Castillo-Rogez et al., Icarus 2001). Such iciness is unusually large for asteroids (or meteorites) as we know them. If Ceres formed in situ, this could be consistent with temporal evolution of the nebular snow-line across the asteroidal zone; icy planetesimals from further out could also contribute, prior to Jupiter formation. In the “grand tack” elaboration of the Nice model, Jupiter and Saturn undergo a two-stage, inward-then-outward, migration (Walsh et al., Nature 2011). Because Jupiter reverses migration direction close in, the primordial asteroid belt is emptied and then repopulated with bodies from both the inner and outer solar system. At Ceres’ position the majority of icy, outer solar system bodies derive from between the giant planets (out to 8 AU in the initial configuration). This new asteroid belt is predicted to be highly dynamically agitated, however, which may not be consistent with 39Ar/40Ar age constraints from meteorites. In the Nice model proper, KBOs/comets are embedded in large numbers into the jovian Trojan clouds and the outer asteroid belt (>2.6 AU) (Levison et al., Nature 2009). Although the model embedded cometary population does not include large bodies (>180 km diameter), the size-frequency distribution can be extended according to various proposed population indices. Without violating the Trojan population constraint, I find that embedding and retaining large (500-to-1000 km diameter) KBOs in the outer asteroid belt generally cannot be statistically ruled out at the 2σ level (though the original steep differential power-law index of Levison et al., -6.5, is not consistent with an embedded Ceres). Chemical and isotopic measurements (especially D/H) will be important future tests of Ceres

  15. NEA rotations and binaries

    NASA Astrophysics Data System (ADS)

    Pravec, Petr; Harris, A. W.; Warner, B. D.

    2007-05-01

    Of nearly 3900 near-Earth asteroids known in June 2006, 325 have got estimated rotation periods. NEAs with sizes down to 10 meters have been sampled. Observed spin distribution shows a major changing point around D=200 m. Larger NEAs show a barrier against spin rates >11 d-1 (period P~2.2 h) that shifts to slower rates with increasing equatorial elongation. The spin barrier is interpreted as a critical spin rate for bodies held together by self-gravitation only, suggesting that NEAs larger than 200 m are mostly strenghtless bodies (i.e., with zero tensile strength), so called `rubble piles'. The barrier disappears at D<200 m where most objects rotate too fast to be held together by self-gravitation only, so a non-zero cohesion is implied in the smaller NEAs. The distribution of NEA spin rates in the `rubble pile' range (D>0.2 km) is non-Maxwellian, suggesting that other mechanisms than just collisions worked there. There is a pile up in front of the barrier (P of 2-3 h). It may be related to a spin up mechanism crowding asteroids to the barrier. An excess of slow rotators is seen at P>30 h. The spin-down mechanism has no clear lower limit on spin rate; periods as long as tens of days occur. Most NEAs appear to be in basic spin states with rotation around the principal axis. Excited rotations are present among and actually dominate in slow rotators with damping timescales >4.5 byr. A few tumblers observed among fast rotating coherent objects consistently appear to be more rigid or younger than the larger, rubble-pile tumblers. An abundant population of binary systems among NEAs has been found. The fraction of binaries among NEAs larger than 0.3 km has been estimated to be 15 +/-4%. Primaries of the binary systems concentrate at fast spin rates (periods 2-3 h) and low amplitudes, i.e., they lie just below the spin barrier. The total angular momentum content in the binary systems suggests that they formed at the critical spin rate, and that little or no angular

  16. Effect of Non-Sphericity of Gravitational Field of the Asteroid on the its Satellites Orbits Evolution

    NASA Astrophysics Data System (ADS)

    Troianskyi, V. V.

    2015-12-01

    Lately it has become possible to sufficiently precise definition of the physical and geometric characteristics of asteroid systems using radar observations (http://echo.jpl.nasa.gov/˜lance/binary.neas.html), which allowed calculating the asymmetry of the massive component of double and multiple asteroids for studying the dynamics of motion of their satellites.

  17. 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.

  18. 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.

  19. 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...

  20. 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.

  1. Ranking asteroid threats

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    “Kiss your asteroid goodbye,” read the March 13, 1998, New York Post headline, which was far more sensational than Asteroid 1997 XF11's feared encounter with the Earth turned out to be. Fortunately, many other asteroids also have proven to be duds. But our pock-marked planet provides proof that occasional chunks of rock do shake up things on the Earth. They also suggest that it might be prudent to have some sort of method for sizing up potential danger—a type of Richter scale for understanding the risks posed by asteroids and comets. A new scale devised for rating the potential for near-Earth object (NEO) collisions with the planet may help to better communicate risks to scientists and the general public, according to the scale's creator, Richard Binzel, professor of Earth, Atmospheric and Planetary Sciences at the Massachusetts Institute of Technology.

  2. Physical properties of asteroids

    NASA Technical Reports Server (NTRS)

    Veeder, G. J.

    1986-01-01

    The physical properties of asteroids were studied by telescopic observations and laboratory and theoretical work. Spectrophotometry from 0.3 to 1.1 microns and 1.2, 1.6 and 2.2 micron photometry allow spectral-compositional classification of asteroids. Based on laboratory data and telescopic observations, it was found that infrared measurements at 1.2, 1.6 and 2.2 microns provide a relatively rapid and accurate method for the classification of minor planets and are important in comparing asteroids with meteorites. This technique was proven and employed in an expanded survey of Apollo-Amor-Aten and other unusual asteroids recently scanned by IRAS.

  3. Asteroid lightcurve studies

    NASA Technical Reports Server (NTRS)

    Harris, A. W.

    1986-01-01

    The use of light curves to characterize the dynamics of asteroids is discussed in a review of recent statistical and theoretical investigations. The summary, detailed, and bibliographic lists comprising the IAU light-curve data set are briefly characterized, and studies of rotation rates, shapes and pole positions, and phase relations are surveyed. Rotation-rate differences among the taxonomic classes and with asteroid size are noted, along with a wide dispersion of rotation rates in objects smaller than about 100 km.

  4. Hilda Asteroid Compositions as an Observational Test of Giant Planet Migration Models

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

    Multiple lines of evidence indicate that planetary migration is a key part of the evolution of planetary systems. Planetary migration models of the solar system suggest that the Jupiter Trojan and Hilda stable resonances were repopulated during giant planet migration. We have completed a 4-year, multi-epoch photomteric multi-color survey of Hilda asteroids in order to determine individual object composition. The colors of ~500 Hildas are now known, a factor of 3 increase in objects with determined compositions compared to the start of our observations. We report the results of our survey in the context of the predictions from current dynamical migration models, identify the model inconsistent with the compositional results, and address future observational data that is required in addition to Hilda asteroid compositions to validate the Nice and Grand Tack models.This work supported by the University of Minnesota Undergraduate Research Scholarship Program and NASA Planetary Astronomy Grant NNX13AJ11G.

  5. 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.

  6. 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

  7. 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

  8. 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

  9. 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

  10. 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

  11. 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,…

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. Jovian Trojans: Orbital structures versus the WISE data

    NASA Astrophysics Data System (ADS)

    Rozehnal, Jakub; Broz, M.

    2013-10-01

    In this work, we study the relation between orbital characteristics of Jovian Trojans and their albedos and diameters as measured by the WISE/NEOWISE mission (Grav et al. 2011, 2012). In our previous work (Broz & Rozehnal 2011), we concluded that there is only one collisional family with parent body size larger than 100 km among Trojans, namely the Eurybates. This finding was based on the analysis of the observed size distributions, colour data from the Sloan Digital Sky Survey, and simulations of orbital evolution. The WISE albedos serve as an independent source of information which allows us to verify our previous results. We also update our database of suitable resonant elements (i.e. the libration amplidude D, eccentricity e, inclination I) of Trojans and we look for new (to-be-discovered) clusters by the Hierarchical Clustering Method. Using the WISE diameters, we can construct more precise size-frequency distributions of Trojans in both the leading/trailing clouds which we compare to SFD of the cluster(s) mentioned above. We then prepare a collisional model (based on the Boulder code, Morbidelli et al. 2009). Initial conditions of our model are based on an assumption that the Trojans were captured from a destabilised transplanetary disc while Jupiter jumped during its close encounter with a Neptune-mass planet - the so-called "jump capture" (Nesvorny et al. 2013). Within the framework of this model we try to constrain the age of the Eurybates family. The work of MB was supported by grant GACR 13-013085 of the Czech Science Foundation and the Research Programme MSM0021620860 of the Czech Ministry of Education.

  17. 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).

  18. 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.

  19. 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.

  20. Asteroid selection for mission opportunities. Appendix: Asteroid data sheets

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The characteristics of asteroids selected as possible space mission objectives are presented. The asteroids are described according to: (1) magnitude, (2) spectral reflectivity; (3) phase factors, (4) polarization, (5) light curve, and (6) physical parameters. The data are tabulated on specific formats for each asteroid considered.

  1. The evolution of asteroids in the jumping-Jupiter migration model

    NASA Astrophysics Data System (ADS)

    Virgilio Roig, Fernando; Nesvorný, David

    2015-11-01

    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 3 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 semi-major 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 ˜10o 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.

  2. The Evolution of Asteroids in the Jumping-Jupiter Migration Model

    NASA Astrophysics Data System (ADS)

    Roig, Fernando; Nesvorný, David

    2015-12-01

    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. 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.

  4. 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 ...

  5. 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...

  6. ISO observations of asteroids

    NASA Astrophysics Data System (ADS)

    Dotto, E.; Barucci, M. A.; Crovisier, J.; Doressoundiram, A.; Encrenaz, Th.; Fulchignoni, M.; Knacke, R.; Lellouch, E.; Morris, P. W.; Müller, T. G.; Owen, T.

    1999-03-01

    Asteroids were observed by ISO with several instruments (PHT-P, PHT-S and SWS). The aim of these observations was to investigate the asteroid physical and compositional properties. Sixteen asteroids have been observed by PHT-P and PHT-S: with PHT-P we obtained the observations at filters 3.6, 10, 11.5, 25, and 60 μm for 10 asteroids and only at filters 3.6 and 10 μm for the other 6 objects. With PHT-S we obtained simultaneously the 2.5-5 and 5.8-11.6 μm spectral ranges. Four of these asteroids have been also observed with SWS between 5.3 and 45 μm. The first analysis of the obtained spectra has shown some features which suggest the presence of oxides (e.g. magnetite, hematite, etc.) among the surface materials of 10 Hygiea and 308 Polyxo, indicating aqueous alteration on the surfaces of these objects.

  7. The Pan-STARRS 1 Discoveries of Five New Neptune Trojans

    NASA Astrophysics Data System (ADS)

    Lin, Hsing Wen; Chen, Ying-Tung; Holman, Matthew J.; Ip, Wing-Huen; Payne, M. J.; Lacerda, P.; Fraser, W. C.; Gerdes, D. W.; Bieryla, A.; Sie, Z.-F.; Chen, W.-P.; Burgett, W. S.; Denneau, L.; Jedicke, R.; Kaiser, N.; Magnier, E. A.; Tonry, J. L.; Wainscoat, R. J.; Waters, C.

    2016-11-01

    In this work, we report the detection of seven Neptune Trojans (NTs) in the Pan-STARRS 1 (PS1) survey. Five of these are new discoveries, consisting of four L4 Trojans and one L5 Trojan. Our orbital simulations show that the L5 Trojan stably librates for only several million years. This suggests that the L5 Trojan must be of recent capture origin. On the other hand, all four new L4 Trojans stably occupy the 1:1 resonance with Neptune for more than 1 Gyr. They can, therefore, be of primordial origin. Our survey simulation results show that the inclination width of the NT population should be between 7° and 27° at >95% confidence, and most likely ∼11°. In this paper, we describe the PS1 survey, the Outer Solar System pipeline, the confirming observations, and the orbital/physical properties of the new NTs.

  8. 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.

  9. 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).

  10. 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

  11. A Technique for Removing an Important Class of Trojan Horses from High-Order Languages

    DTIC Science & Technology

    1988-01-01

    A Technique for Removing an Important Class of Trojan Horses from High Order Languages∗ John McDermott Center for Secure Information Technology...Ken Thompson described a sophisticated Trojan horse attack on a compiler, one that is undetectable by any search of the compiler source code. The...object of the compiler Trojan horse is to modify the semantics of the high order language in a way that breaks the security of a trusted system generated

  12. Building a Better Trojan Horse: Emerging Army Roles in Joint Urban Operations

    DTIC Science & Technology

    2001-01-01

    Building a Better Trojan Horse : Emerging Army Roles in Joint Urban Operations A Monograph by MAJ Christopher H. Beckert Infantry, U.S. Army School...xx-xx-2000 to xx-xx-2000 5a. CONTRACT NUMBER 5b. GRANT NUMBER 4. TITLE AND SUBTITLE Building a Better Trojan Horse : Emerging Army Roles in Joint...TELEPHONE NUMBER International Area Code Area Code Telephone Number 703 767-9007 DSN 427-9007 2 Abstract BUILDING A BETTER TROJAN HORSE : EMERGING ARMY

  13. Discovery of the triple asteroidal system 87 Sylvia.

    PubMed

    Marchis, Franck; Descamps, Pascal; Hestroffer, Daniel; Berthier, Jérome

    2005-08-11

    After decades of speculation, the existence of binary asteroids has been observationally confirmed, with examples in all minor planet populations. However, no triple systems have hitherto been discovered. Here we report the unambiguous detection of a triple asteroidal system in the main belt, composed of a 280-km primary (87 Sylvia) and two small moonlets orbiting at 710 and 1,360 km. We estimate their orbital elements and use them to refine the shape of the primary body. Both orbits are equatorial, circular and prograde, suggesting a common origin. Using the orbital information to estimate its mass and density, 87 Sylvia appears to have a rubble-pile structure with a porosity of 25-60 per cent. The system was most probably formed through the disruptive collision of a parent asteroid, with the new primary resulting from accretion of fragments, while the moonlets are formed from the debris, as has been predicted previously.

  14. Manuel's asteroid disruption technique.

    PubMed

    John, Manuel; Ipe, Abraham; Jacob, Ivan

    2015-06-01

    A seventy-year-old male presented with dense asteroid hyalosis in both eyes. He had undergone cataract extraction in one eye 3 years ago, and the other eye had immature cataract. Both the autorefractor and dilated streak retinoscopy did not give readings and subjective visual improvement could not be achieved. Immediately following YAG posterior capsulotomy and anterior vitreous asteroid disruption, the vision improved to 20/20 with recordable auto refractor and streak retinoscopy values. Our initial experience indicates that the treatment is simple, safe and effective but needs controlled and prospective studies to confirm its long-term safety.

  15. Radar investigation of asteroids

    NASA Technical Reports Server (NTRS)

    Ostro, S. J.

    1984-01-01

    The initial radar observations of the mainbelt asteroids 9 Metis, 27 Euterpe, and 60 Echo are examined. For each target, data are taken simultaneously in the same sense of circular polarization as transmitted as well as in the opposite (OC) sense. Estimates of the radar cross sections provide estimates of the circular polarization ratio, and the normalized OC radar cross section. The circular polarization ratio, is comparable to values measured for other large S type asteroids and for a few much smaller, Earth approaching objects, most of the echo is due to single reflection backscattering from smooth surface elements.

  16. A Re-examination of the Lightcurves for Seven Hungaria Asteroids

    NASA Astrophysics Data System (ADS)

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

    2009-10-01

    During the course of a study of long period asteroids (f < 1/d) within the Hungaria asteroid population, the lightcurves for seven asteroids were re-examined using updated software and techniques. Several were found to have significantly different periods from those previously reported by two of the authors (Warner and Stephens). The most significant change was 2074 Shoemaker, which was initially reported to have a period of 57 h but now appears to be a binary asteroid with a primary period of 2.5328 ± 0.0004 h and a possible orbital period of 55.52 ± 0.01 h. The other asteroids that were re-examined were 1919 Clemence, 3043 San Diego, 3353 Jarvis, 4142 Dersu-Uzala, (20232) 1997 YK, and (101549) 1998 YY2. The reexamination showed once again the importance of placing data on at least an internal system to achieve accurate night-to-night calibrations.

  17. NASA's Asteroid Redirect Mission (ARM)

    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.

    2017-01-01

    Mission Description and Objectives: NASA's Asteroid Redirect Mission (ARM) consists of two mission segments: 1) the Asteroid Redirect Robotic Mission (ARRM), a robotic mission to visit a large (greater than approximately 100 meters diameter) near-Earth asteroid (NEA), collect a multi-ton boulder from its surface along with regolith samples, and return the asteroidal material to a stable orbit around the Moon; and 2) the Asteroid Redirect Crewed Mission (ARCM), in which astronauts will explore and investigate the boulder and return to Earth with samples. The ARRM is currently planned to launch at the end of 2021 and the ARCM is scheduled for late 2026.

  18. 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

  19. 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

  20. 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.

  1. 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).

  2. Asteroid capture using lunar flyby

    NASA Astrophysics Data System (ADS)

    Gong, Shengping; Li, Junfeng

    2015-09-01

    This paper focuses on the approach which enables us to capture an asteroid using the lunar flyby. Assume that the asteroid is able to enter the Earth-Moon system. The orbits of the asteroid before and after lunar flybys are investigated for different Jacobi constants in the restricted three body problem. The capture will happen when the post-flyby Jacobi constant reaches certain value due to the flyby. The capture regions of different pre-flyby initial Jacobi constants are numerically explored in the diagram that is represented by two defined angles. To give an intuitive description of the capture region, it is represented by the orbital elements of the asteroid. Based on this capture region, the asteroids that can be captured through lunar flybys are chosen from the asteroid database. Finally, the capture processes of selected asteroids are validated through the ephemerides model.

  3. (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.

  4. The superficial characterization of a large sample of asteroids: the S3OS2

    NASA Astrophysics Data System (ADS)

    Lazzaro, D.; Angeli, C. A.; Mothe-Diniz, T.; Carvano, J. M.; Duffard, R.; Florczak, M.

    2002-09-01

    Informations about the compositional and mineralogical properties of a large sample of asteroids is important to better constraint their formation and evolution. In this sense large surveys have been performed in the last years either through photometric or spectroscopic observations (ex.: ECAS, 52colours, SMASS, etc.) with nearly 2000 asteroids sampled. However, in view of the steadly increasing number of known asteroids this sample is still in need of more data in order to have a complete knowledge of the distribution of compositions. The purpose of the Small Solar System Objects Spectroscopic Survey - S3OS2, was to contribute to increase the database of known superficial composition of asteroids in the visible range. The S3OS2 was performed at the European Southern Observatory (La Silla, Chile) under the agreement with the Observatorio Nacional, using the 1.52-m telescope equipped with a Boller & Chivens Spectrograph and a CCD. The survey was carried on from November 1996 up to September 2001 and visible spectra, in the range 4900-9200 Angstrom, were obtained for 843 asteroids. All these spectra will be available at the homepage of the Observatorio Nacional (http://www.on.br/institucional/) starting on October/2002. The taxonomic classification of all the sample will also be available at the same site. The spatial distribution of S3OS2 range from the Near Earth region, around 1.5 AU, up the Trojan region, around 5.2AU. Several families have been studied as well as several groups, all of which have been object of specific papers. In this presentation we will discuss the general properties and results of the survey, in view of what these represent for a better understanding about the formation and subsequent collisional and dynamical evolution of the asteroid belt as a whole. The author acknowledge the funding from CNPq, FAPERJ and CAPES.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. A Trojan horse mechanism of bacterial pathogenesis against nematodes

    PubMed Central

    Niu, Qiuhong; Huang, Xiaowei; Zhang, Lin; Xu, Jianping; Yang, Dongmei; Wei, Kangbi; Niu, Xuemei; An, Zhiqiang; Bennett, Joan Wennstrom; Zou, Chenggang; Yang, Jinkui; Zhang, Ke-Qin

    2010-01-01

    Understanding the mechanisms of host–pathogen interaction can provide crucial information for successfully manipulating their relationships. Because of its genetic background and practical advantages over vertebrate model systems, the nematode Caenorhabditis elegans model has become an attractive host for studying microbial pathogenesis. Here we report a “Trojan horse” mechanism of bacterial pathogenesis against nematodes. We show that the bacterium Bacillus nematocida B16 lures nematodes by emitting potent volatile organic compounds that are much more attractive to worms than those from ordinary dietary bacteria. Seventeen B. nematocida-attractant volatile organic compounds are identified, and seven are individually confirmed to lure nematodes. Once the bacteria enter the intestine of nematodes, they secrete two proteases with broad substrate ranges but preferentially target essential intestinal proteins, leading to nematode death. This Trojan horse pattern of bacterium–nematode interaction enriches our understanding of microbial pathogenesis. PMID:20733068

  11. Trojan-horse attacks on quantum-key-distribution systems

    SciTech Connect

    Gisin, N.; Fasel, S.; Kraus, B.; Zbinden, H.; Ribordy, G.

    2006-02-15

    General Trojan-horse attacks on quantum-key-distribution systems, i.e., attacks on Alice or Bob's system via the quantum channel, are analyzed. We illustrate the power of such attacks with today's technology and conclude that all systems must implement active counter measures. In particular, all systems must include an auxiliary detector that monitors any incoming light. We show that such counter measures can be efficient, provided that enough additional privacy amplification is applied to the data. We present a practical way to reduce the maximal information gain that an adversary can gain using Trojan-horse attacks. This does reduce the security analysis of the two-way plug-and-play implementation to those of the standard one-way systems.

  12. 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.

  13. Hardware Trojans - Prevention, Detection, Countermeasures (A Literature Review)

    DTIC Science & Technology

    2011-07-01

    Testing Given the huge logical space in a modern IC, constructing a test vector that covers the entire IC logic space is computationally infeasible...20 5.2.2.3 Side-Channel Analysis . . . . . . . . . . . . . . . . . . 21 6 Countermeasures 23 6.1 Data Guards...spectrum of Hardware Trojans – their capabilities, size, trigger mechanisms, and payloads – is enormous, and the state- space of IC development both

  14. 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.

  15. Spacecraft exploration of asteroids - The 1988 perspective

    NASA Technical Reports Server (NTRS)

    Veverka, J.; Langevin, Y.; Farquhar, R.; Fulchignoni, M.

    1989-01-01

    Planned and proposed missions to study asteroids are examined. The history of asteroid studies in the 1980s is reviewed, including the proposed Mainbelt Asteroid Orbiter/Flyby mission. Main-belt asteroid flyby missions are discussed, including the Galileo, Cassini, and Comet Rendezvous Asteroid Flyby mission. Also, consideration is given to proposed missions to near-earth asteroids, the Vesta mission to perform in situ studies on two large asteroids, the Piazzi mission to flyby an Apollo-Amor-Aten asteroid using a Giotto-derived spacecraft, and the possibility of a Japanese asteroid flyby mission.

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. Active Asteroids: Main-Belt Comets and Disrupted Asteroids

    NASA Astrophysics Data System (ADS)

    Hsieh, Henry H.

    2016-10-01

    The study of active asteroids has attracted a great deal of interest in recent years since the recognition of main-belt comets (which orbit in the main asteroid belt, but exhibit comet-like activity due to the sublimation of volatile ices) as a new class of comets in 2006, and the discovery of the first disrupted asteroids (which, unlike MBCs, exhibit comet-like activity due to a physical disruption such as an impact or rotational destabilization, not sublimation) in 2010. In this paper, I will briefly discuss key areas of interest in the study of active asteroids.

  2. 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.

  3. A Statistical Search for a Population of Exo-Trojans in the Kepler Data Set

    NASA Astrophysics Data System (ADS)

    Hippke, Michael; Angerhausen, Daniel

    2015-09-01

    Trojans are small bodies in planetary Lagrangian points. In our solar system, Jupiter has the largest number of such companions. Their existence is assumed for exoplanetary systems as well, but none have been found so far. We present an analysis by super-stacking ∼4 × 103 Kepler planets with a total of ∼9 × 104 transits, searching for an average Trojan transit dip. Our results give an upper limit to the average Trojan transiting area (per planet) that corresponds to one body of radius \\lt 460 {km} with 2σ confidence. We find a significant Trojan-like signal in a sub-sample for planets with more (or larger) Trojans for periods >60 days. Our tentative results can and should be checked with improved data from future missions like PLATO 2.0, and can guide planetary formation theories.

  4. 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.

  5. 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.

  6. 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.

  7. Radar investigation of asteroids

    NASA Astrophysics Data System (ADS)

    Ostro, S. J.

    1981-07-01

    Radar investigations were conducted of selected minor planets, including: (1) observations during 1981-82 of 10 potential targets (2 Pallas, 8 Flora, 12 Victoria, 15 Eunomia, 19 Fortuna, 22 Kalliope, 132 Aethra, 219 Thusnelda, 433 Eros, and 2100 Ra-Shalom); and (2) continued analyses of observational data obtained during 1980-81 for 10 other asteroids (4 Vesta, 7 Iris, 16 Psyche, 75 Eurydike, 97 Klotho, 216 Kleopatra, 1685 Toro, 1862 Apollo, 1865 Cerberus, and 1915 Quetzalcoatl). Scientific objectives include estimation of echo strength, polarization, spectral shape, spectral bandwidth, and Doppler shift. These measurements: (1) yield estimates of target size, shape, and spin vector; (2) place constraints on topography, morphology, and composition of the planetary surface; (3) yield refined estimates of target orbital parameters; (4) reveal the presence of asteroidal satellites.

  8. 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

  9. 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?

  10. The Rafita asteroid family

    NASA Astrophysics Data System (ADS)

    Aljbaae, S.; Carruba, V.; Masiero, J. R.; Domingos, R. C.; Huaman, M.

    2017-01-01

    The Rafita asteroid family is an S-type group located in the middle main belt, on the right side of the 3J:-1A mean-motion resonance. The proximity of this resonance to the family left side in semi-major axis caused many former family members to be lost. As a consequence, the family shape in the (a, 1/D) domain is quite asymmetrical, with a preponderance of objects on the right side of the distribution. The Rafita family is also characterized by a leptokurtic distribution in inclination, which allows the use of methods of family age estimation recently introduced for other leptokurtic families such as Astrid, Hansa, Gallia, and Barcelona. In this work we propose a new method based on the behavior of an asymmetry coefficient function of the distribution in the (a, 1/D) plane to date incomplete asteroid families such as Rafita. By monitoring the time behavior of this coefficient for asteroids simulating the initial conditions at the time of the family formation, we were able to estimate that the Rafita family should have an age of 490 ± 200 Myr, in good agreement with results from independent methods such as Monte Carlo simulations of Yarkovsky and Yorp dynamical induced evolution and the time behaviour of the kurtosis of the sin (i) distribution. Asteroids from the Rafita family can reach orbits similar to 8% of the currently known near Earth objects. ≃1% of the simulated objects are present in NEO-space during the final 10 Myr of the simulation, and thus would be comparable to objects in the present-day NEO population.

  11. 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.

  12. The intrinsic Neptune Trojan orbit distribution: Implications for the primordial disk and planet migration

    NASA Astrophysics Data System (ADS)

    Parker, Alex H.

    2015-02-01

    The present-day orbit distribution of the Neptune Trojans is a powerful probe of the dynamical environment of the outer Solar System during the late stages of planet migration. In this work, I conservatively debias the inclination, eccentricity, and libration amplitude distributions of the Neptune Trojans by reducing a priori unknown discovery and follow-up survey properties to nuisance parameters and using a likelihood-free Bayesian rejection sampler for parameter estimation. Using this survey-agnostic approach, I confirm that the Neptune Trojans are a dynamically excited population: at >95% confidence, the Neptune Trojans' inclination width must be σi>11° . For comparison and motivation purposes, I also model the Jupiter Trojan orbit distributions in the same basis and produce new estimates of their parameters (Jupiter Trojan σi=14.4° ±0.5° , σL11=11.8° ±0.5° , and σe=0.061±0.002 ). The debiased inclination, libration amplitude, and eccentricity distributions of the Neptune Trojans are nominally very similar to those of the Jupiter Trojans. I use these new constraints to inform a suite of simulations of Neptune Trojan capture by an eccentric, rapidly-migrating Neptune from an initially dynamically-hot disk. These simulations demonstrate that if migration and eccentricity-damping timescales were short (τa≲ 10 Myr, τe≲ 1 Myr), the disk that Neptune migrated into must have been pre-heated (prior to Neptune's appearance) to a width comparable to the Neptune Trojans' extant width to produce a captured population with an inclination distribution width consistent with that of the observed population.

  13. 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.

  14. 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.

  15. The taxonomic distribution of asteroids from multi-filter all-sky photometric surveys

    NASA Astrophysics Data System (ADS)

    DeMeo, F. E.; Carry, B.

    2013-09-01

    The distribution of asteroids across the main belt has been studied for decades to understand the current compositional distribution and what that tells us about the formation and evolution of our Solar System. All-sky surveys now provide orders of magnitude more data than targeted surveys. We present a method to bias-correct the asteroid population observed in the Sloan Digital Sky Survey (SDSS) according to size, distance, and albedo. We taxonomically classify this dataset consistent with the Bus and Binzel (Bus, S.J., Binzel, R.P. [2002]. Icarus 158, 146-177) and Bus-DeMeo et al. (DeMeo, F.E., Binzel, R.P., Slivan, S.M., Bus, S.J. [2009]. Icarus 202(July), 160-180) systems and present the resulting taxonomic distribution. The dataset includes asteroids as small as 5 km, a factor of three in diameter smaller than in previous work such as by Mothé-Diniz et al. (Mothé-Diniz, T., Carvano, J.M.Á., Lazzaro, D. [2003]. Icarus 162(March), 10-21). Because of the wide range of sizes in our sample, we present the distribution by number, surface area, volume, and mass whereas previous work was exclusively by number. While the distribution by number is a useful quantity and has been used for decades, these additional quantities provide new insights into the distribution of total material. We find evidence for D-types in the inner main belt where they are unexpected according to dynamical models of implantation of bodies from the outer Solar System into the inner Solar System during planetary migration (Levison, H.F., Bottke, W.F., Gounelle, M., Morbidelli, A., Nesvorný, D., Tsiganis, K. [2009]. Nature 460(July), 364-366). We find no evidence of S-types or other unexpected classes among Trojans and Hildas, albeit a bias favoring such a detection. Finally, we estimate for the first time the total amount of material of each class in the inner Solar System. The main belt’s most massive classes are C, B, P, V and S in decreasing order. Excluding the four most massive

  16. 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.

  17. 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

  18. 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

  19. 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

  20. Origin and dynamical evolution of Neptune Trojans - II. Long-term evolution

    NASA Astrophysics Data System (ADS)

    Lykawka, P. S.; Horner, J.; Jones, B. W.; Mukai, T.

    2011-03-01

    Following our earlier work studying the formation of the Neptunian Trojan population during the planet's migration, we present results examining the eventual fate of the Trojan clouds produced in that work. A large number of Trojans were followed under the gravitational influence of the giant planets for a period of at least 1 Gyr. We find that the stability of Neptunian Trojans seems to be strongly correlated to their initial post-migration orbital elements, with those objects that survive as Trojans for billions of years, displaying negligible orbital evolution. The great majority of these survivors began the integrations with small eccentricities (e < 0.2) and small libration amplitudes (A < 30°-40°). The survival rate of 'pre-formed' Neptunian Trojans [which in general survived on dynamically cold orbits (e < 0.1, i < 5°-10°)] varied between ˜5 and 70 per cent, depending on the precise detail of their initial orbits. In contrast, the survival rate of 'captured' Trojans (on final orbits spread across a larger region of the e-i element space) was markedly lower, ranging between 1-10 per cent after 4 Gyr. Taken in concert with our earlier work and the broad i-distribution of the observed Trojan population, we note that planetary formation scenarios, which involve the slow migration (a few tens of millions of years) of Neptune from an initial planetary architecture that is both resonant and compact (aN < 18 au), provide the most promising fit of those we considered to the observed Trojan population. In such scenarios, we find that the present-day Trojan population would number ˜1 per cent of that which was present at the end of the planet's migration (i.e. survival rate of ˜1 per cent), with the bulk being sourced from captured, rather than pre-formed objects. We note, however, that even those scenarios still fail to reproduce the presently observed portion of the Neptune Trojan population moving on orbits with e < 0.1 but i > 20°. Dynamical integrations of

  1. 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.

  2. 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.

  3. Plutinos and Trojans as Probes of Planet Building

    NASA Astrophysics Data System (ADS)

    Alexandersen, Mike; Gladman, B. J.; Kavelaars, J. J.; Petit, J.

    2012-10-01

    Previous work has shown steep power-law distributions in the TNO region for diameters > 100 km. Recent results claim a dramatic roll-over in the size distribution of Neptune Trojans and other KBO populations, with a strong deficit of intermediate-size planetesimals with D<100 km. One interpretation is that planetesimals were born big, skipping the intermediate sizes. Regardless of interpretation, exploration of the TNO size distribution requires more precisely calibrated detections in order to improve statistics on these results (there are, for example, only seven known Neptune Trojans). In 2011 we used MegaCam on the Canada-France-Hawaii Telescope to begin surveying 40 square degrees in the Neptune L4 region, where Trojans reside and many Plutinos & other TNOs come to perihelion. We acquired 42 hours of r-band imaging. In the better-quality half of the observations (20 sq. deg.) we have discovered 70 TNOs with a search limit of m_r 24.5 (m_g 25.0). Most of the discovered TNOs have successfully been tracked over several months of arc, giving us high-quality orbits, with the goal of tracking every TNO brighter than some a limit (roughly 24.5) to a high quality orbit so that they can be precisely modelled. In August to December 2012 we will obtain another 42 hours of follow-up observations to complete this project. Here we present some preliminary results of the survey, concentrating on the Plutino population coupled with the CFEPS L7 Plutino model (Gladman et al., 2012, AJ, 144, 23) in order to study the Plutino size distribution. This research was supported by the Canadian National Sciences and Engineering Research Council.

  4. 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.

  5. 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.

  6. 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

  7. Ethics as a beneficial Trojan horse in a technological society.

    PubMed

    Queraltó, Ramón

    2013-03-01

    This article explores the transformation of ethics in a globalizing technological society. After describing some basic features of this society, particularly the primacy it gives to a special type of technical rationality, three specific influences on traditional ethics are examined: (1) a change concerning the notion of value, (2) the decreasing relevance of the concept of axiological hierarchy, and (3) the new internal architecture of ethics as a net of values. These three characteristics suggest a new pragmatic understanding of ethics. From a pragmatic perspective, the process of introducing ethical values into contemporary society can be regarded as a beneficial Trojan horse, a metaphor that will be developed further.

  8. 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

  9. Stability and capture of asteroids

    NASA Technical Reports Server (NTRS)

    Szebehely, V.

    1983-01-01

    The problem of stability of asteroids is treated from the point of view of Hill's stability-concept and using Lyapunov's Characteristic Numbers. The quantitative measure of stability (S) introduced earlier is evaluated for over 300 asteroids and a surprisingly simple relation is established between the semi-major axes of some of the asteroids' orbits and S. A detailed analysis is presented of the Lyapunov Characteristic Numbers for two minor planets and the time-variation of these numbers is discussed. The technology of capture of asteroids is vitally dependent on their orbital stability, therefore, these two problems, i.e., capture and stability, are closely related. In fact, some predictable instabilities may be properly utilized to capture and/or change asteroidal orbits to accomplish collisions with the Earth.

  10. Asteroid electrostatic instrumentation and modelling

    NASA Astrophysics Data System (ADS)

    Aplin, K. L.; Bowles, N. E.; Urbak, E.; Keane, D.; Sawyer, E. C.

    2011-06-01

    Asteroid surface material is expected to become photoelectrically charged, and is likely to be transported through electrostatic levitation. Understanding any movement of the surface material is relevant to proposed space missions to return samples to Earth for detailed isotopic analysis. Motivated by preparations for the Marco Polo sample return mission, we present electrostatic modelling for a real asteroid, Itokawa, for which detailed shape information is available, and verify that charging effects are likely to be significant at the terminator and at the edges of shadow regions for the Marco Polo baseline asteroid, 1999JU3. We also describe the Asteroid Charge Experiment electric field instrumentation intended for Marco Polo. Finally, we find that the differing asteroid and spacecraft potentials on landing could perturb sample collection for the short landing time of 20min that is currently planned.

  11. 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.

  12. 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.

  13. Radar investigation of asteroids

    NASA Technical Reports Server (NTRS)

    Ostro, S. J.

    1981-01-01

    Efforts were focused on: (1) acquisition of radar data at Arecibo; (2) examination of raw data; (3) reduction of the unmodulated data to background-free, calibrated spectra; (4) integration and coherent analyses of the phase-coded data; and (5) calculation of Doppler shifts and preliminary values for echo limb-to-limb bandwidths, radar cross sections, and circular polarization ratios. Asteroids observed to data have radar properties distinct from those of the rocky terrestrial planets and those of the icy Galilean satellites.

  14. 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.

  15. Temporary Capture of Asteroids by a Planet: Dependence of Prograde/Retrograde Capture on Asteroids’ Semimajor Axes

    NASA Astrophysics Data System (ADS)

    Higuchi, A.; Ida, S.

    2016-01-01

    We have investigated the dependence of the prograde/retrograde temporary capture of asteroids by a planet on their original heliocentric semimajor axes through analytical arguments and numerical orbital integrations in order to discuss the origins of irregular satellites of giant planets. We found that capture is mostly retrograde for the asteroids near the planetary orbit and is prograde for those from farther orbits. An analytical investigation reveals the intrinsic dynamics of these dependences and gives boundary semimajor axes for the change in prograde/retrograde capture. The numerical calculations support the idea of deriving analytical formulae and confirm their dependence. Our numerical results show that the capture probability is much higher for bodies from the inner region than for outer ones. These results imply that retrograde irregular satellites of Jupiter are most likely captured bodies from the nearby orbits of Jupiter that may have the same origin as Trojan asteroids, while prograde irregular satellites originate from far inner regions such as the main-belt asteroid region.

  16. Modeling Momentum Transfer from Kinetic Impacts: Implications for Redirecting Asteroids

    DOE PAGES

    Stickle, A. M.; Atchison, J. A.; Barnouin, O. 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

  17. 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.

  18. 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

  19. Binary Plutinos

    NASA Astrophysics Data System (ADS)

    Noll, Keith S.

    2015-08-01

    The Pluto-Charon binary was the first trans-neptunian binary to be identified in 1978. Pluto-Charon is a true binary with both components orbiting a barycenter located between them. The Pluto system is also the first, and to date only, known binary with a satellite system consisting of four small satellites in near-resonant orbits around the common center of mass. Seven other Plutinos, objects in 3:2 mean motion resonance with Neptune, have orbital companions including 2004 KB19 reported here for the first time. Compared to the Cold Classical population, the Plutinos differ in the frequency of binaries, the relative sizes of the components, and their inclination distribution. These differences point to distinct dynamical histories and binary formation processes encountered by Plutinos.

  20. 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.

  1. 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.

  2. Asteroid, Meteor, Meteorite

    NASA Astrophysics Data System (ADS)

    Martel, L. M. V.

    2010-04-01

    Almahata Sitta is the name identifying the collection of meteorite remnants of the first observed fall of a tracked asteroid, 2008 TC3. Ground-based observatories, orbiting satellites, a pilot of a commercial airline flight, and eyewitnesses of the fireball in the Nubian Desert of northern Sudan all observed evidence of the spectacular events on October 6, 2008. The first meteorites were recovered two months later in Sudan by students and staff from the University of Khartoum (Sudan) led by Dr. Muawia Shaddad and further guided by Dr. Peter Jenniskens of the SETI Institute and NASA Ames Research Center (Mt. View, California). A session at the 41st Lunar and Planetary Science Conference held March 1-5, 2010 focused on ureilitic asteroids and insights from Almahata Sitta, and forms the basis for this article. Rather than discuss the results of each of the talks and posters presented at the conference, I highlight what makes the impact, recovery, and characterization of the ureilite meteorite fragments so outstanding.

  3. 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.

  4. 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.

  5. Design study for asteroidal exploitation

    NASA Astrophysics Data System (ADS)

    Adams, Carl; Blissit, Jim; Jarrett, Dave; Sanner, Rob; Yanagawa, Koji

    1985-08-01

    A systematic approach to asteroidal exploitation for the 1990 to 2010 time frame is presented as an initial step toward expanding the use of space beyond the space station by providing a source of lower cost materials. With only a limited amount of information known about the asteroids, reconnaissance and exploration phases to determine the exact locations and compositions of several earth-approaching asteroids are required. Earth-based telescopes are used to locate and study the asteroids, while unmanned probes will return samples of asteroidal material to earth for analysis. After these phases are completed, the retrieval of a 35,000 metric ton piece of the asteroid Anteros is undertaken. A cargo transporter uses magnetoplasmadynamic (MPD) arcjets outbound and a mass-driver using asteroidal material inbound. A crew ship uses ion engines. Low thrust trajectories are used for both spacecraft. A materials processing facility will manufacture propellant pellets and retrieve non-propellant materials for spacecraft use. The cost is 1/10th that to transport the same materials from earth to high earth orbit. The project will cost 25 percent less if done in conjunction with a lunar and Martian base.

  6. Compositional studies of primitive asteroids

    NASA Technical Reports Server (NTRS)

    Vilas, F.

    1988-01-01

    The composition of primitive asteroids and their relationship to satellites in the solar system will be studied by analyzing existing narrowband charge coupled device (CCD) reflectance spectra, acquiring additional spectra of asteroids and small satellites in the 0.5 to 1.0 micrometer spectral range, and exploring possibilities for obtaining compositional information in the blue-UV spectral region. Comparison with laboratory spectra of terrestrial chlorites and serpentines (phyllosilicates) and the clay minerals found in carbonaceous chondrite meteorites will continue. During 1987, narrowband CCD reflectance spectra of 17 additional asteroids were acquired. These spectra and spectra of 34 other asteroids have been used primarily for two studies: weak absorption features similar to those due to Fe2(+) and Fe2(+) - Fe3(+) transitions in iron oxides f ound in terrestrial chlorites and serpentines and carbonaceous chondrites have been identified in some primitive asteroid spectra. There is a first indication that asteroids grouped by heliocentric distance show similar weak absorption features. Nonparametric statistics are being applied to test the hypothesis of discrete remnants of a gradation in composition of outer-belt asteroids.

  7. 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.

  8. Mine Planning for Asteroid Orebodies

    NASA Astrophysics Data System (ADS)

    Gertsch, L. S.; Gertsch, R. E.

    2000-01-01

    Given that an asteroid (or comet) has been determined to contain sufficient material of value to be potentially economic to exploit, a mining method must be selected and implemented. This paper discusses the engineering necessary to bring a mine online, and the opportunities and challenges inherent in asteroid mineral prospects. The very important step of orebody characterization is discussed elsewhere. The mining methods discussed here are based on enclosing the asteroid within a bag in some fashion, whether completely or partially. In general, asteroid mining methods based on bags will consist of the following steps. Not all will be required in every case, nor necessarily in this particular sequence. Some steps will be performed simultaneously. Their purpose is to extract the valuable material from the body of the asteroid in the most efficient, cost-effective manner possible. In approximate order of initiation, if not of conclusion, the steps are: 1. Tether anchoring to the asteroid. 2. Asteroid motion control. 3. Body/fragment restraint system placement. 4. Operations platform construction. 5. Bag construction. 6. Auxiliary and support equipment placement. 7. Mining operations. 8. Processing operations. 9. Product transport to markets.

  9. Radiometry of near-earth asteroids

    NASA Technical Reports Server (NTRS)

    Veeder, G. J.; Hanner, M. S.; Matson, D. L.; Tedesco, E. F.; Lebofsky, L. A.

    1989-01-01

    Infrared photometry is reported 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.

  10. An International Asteroid Search Campaign

    NASA Astrophysics Data System (ADS)

    Miller, J. Patrick; Davis, Jeffrey W.; Holmes, Robert E., Jr.; Devore, Harlan; Raab, Herbert; Pennypacker, Carlton R.; White, Graeme L.; Gould, Alan

    The International Asteroid Search Campaign (IASC, fondly nicknamed "Isaac") is an Internet- based program for high schools and colleges. Within hours of acquisition, astronomical CCD images are made available via the Internet to participating schools around the world. Under the guidance of their teachers, students analyze the images with free software tools, searching for new asteroids and confirmations of near- Earth objects (NEOs). These discoveries are reported to the Minor Planet Center (MPC; Smithsonian Astrophysical Observatory, Harvard), which gives the students published recognition in its MPC circulars. To date, 36 new Main Belt asteroids have been found in one year, and 197 NEOs confirmed.

  11. Vertical landing on an asteroid

    NASA Technical Reports Server (NTRS)

    Harel, D.; Geulman, M.

    1992-01-01

    This work is concerned with the final approach phase and vertical landing on an asteroid with a power-limited, electrically propelled spacecraft. With gravitational effects taken into account, a new solution to the fuel optimal vertical landing on an asteroid was obtained. In this solution, the spacecraft commanded acceleration is explicitly expressed as a function of vehicle velocity and time to go. Based on qualitative methods of analysis, the guidance strategy and the resulting trajectories were studied. It is shown that these fuel-optimal trajectories effectively assure a vertical soft landing on the asteroid. Results of numerical simulations for the vertical landing, starting from an elliptical orbit are presented.

  12. 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

  13. Exploring Main Belt Asteroids

    NASA Astrophysics Data System (ADS)

    Sykes, M. V.; Larson, S. M.; Whiteley, R.; Fink, U.; Jedicke, R.; Emery, J.; Fevig, R.; Kelley, M.; Harris, A. W.; Ostro, S.; Reed, K.; Binzel, R. P.; Rivkin, A.; Magri, C.; Bottke, W.; Durda, D.; Walker, R.; Davis, D.; Hartmann, W. K.; Sears, D.; Yano, H.; Granahan, J.; Storrs, A.; Bus, S. J.; Bell, J. F.; Tholen, D.; Cellino, A.

    2001-11-01

    Terrestrial planet formation in the main asteroid belt was interrupted when growing protoplanets became sufficiently massive to gravitationally perturb the local population, causing bodies to collide with increased energy, thus ending accretion and commencing fragmentation and disruption. Few of these protoplanets are thought to have survived unshattered (e.g., Ceres, Vesta, Pallas), leaving a main belt population dominated by fragments of fragments, and significantly depleted of mass as a consequence of dynamical scattering. Yet, these fragments retain a record of the early steps of planet formation and evolution, as well as a record of early solar system conditions and the primordial composition gradient in that region. By exploring main belt asteroids through groundbased observations and spacecraft, modeling and theoretical work, we seek ultimately to recover this information. A single mission to a single target is not sufficient to address, in isolation, these questions. They require a foundation of robust, broad, and continuing groundbased, theoretical, and modeling programs. Such work is funded at a small fraction of a typical mission cost through the NASA Research and Analysis Program. Therefore, within the context of planetary decadal study recommendations to NASA, highest priority needs to be given to maintaining and growing a healthy R&A program over the next ten years and beyond. Missions also have an important role to play. An Earth orbiting remote sensing mission needs to be considered as a means of collecting important data for a large fraction of all main belt asteroids above a sub-kilometer diameter (while also realizing synergistic benefits to astrophysics). Missions to specific main belt targets can provide important new insights and leverage new understanding of existing data, models, and theories, but target definition (and corresponding instrument complement) is critical and must be based on our existing knowledge of these very diverse objects

  14. Formal detection method for hardware vulnerabilities and Trojan of embedded devices

    NASA Astrophysics Data System (ADS)

    Xie, Xiaodong; Li, Qingbao; Niu, Xiaopeng

    2013-03-01

    As become more widely used, embedded systems security has increasingly gained attention. From the hardware point of view, this paper describes the background of approach to the vulnerabilities and hardware Trojan detection of embedded system, basic ideas and objectives; established the model- ESM (Embedded Systems Model) used to describe embedded systems, provides the encoding method of the ESM system state. Based on this model, this article describes how to use model checking methods to detect vulnerabilities and Trojan existence of an embedded system.

  15. 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

  16. Radar investigation of asteroids

    NASA Technical Reports Server (NTRS)

    Ostro, S. J.

    1983-01-01

    For 80 Sappho, 356 Liguria, 694 Ekard, and 2340 Hathor, data were taken simultaneously in the same sense of circular polarization as transmitted (SC) as well as in the opposite (OC) sense. Graphs show the average OC and SC radar echo power spectra soothed to a resolution of EFB Hz and plotted against Doppler frequency. Radar observations of the peculiar object 2201 Oljato reveal an unusual set of echo power spectra. The albedo and polarization ratio remain fairly constant but the bandwidths range from approximately 0.8 Hz to 1.4 Hz and the spectral shapes vary dramatically. Echo characteristics within any one date's approximately 2.5-hr observation period do not fluctuate very much. Laboratory measurements of the radar frequency electrical properties of particulate metal-plus-silicate mixtures can be combined with radar albedo estimates to constrain the bulk density and metal weight, fraction in a hypothetical asteroid regolith having the same particle size distribution as lab samples.

  17. Radar investigation of asteroids

    NASA Technical Reports Server (NTRS)

    Ostro, S. J.

    1982-01-01

    The dual polarization CW radar system which permits simultaneous reception in the same rotational sense of circular polarization as transmitted (i.e., the "SC" sense) and in the opposite ("OC") sense, was used to observe five previously unobserved asteroids: 2 Pallas, 8 Flora, 22 Kalliope, 132 Aethra, and 471 Papagena. Echoes from Pallas and Flora were easily detected in the OC sense on each of several nights. Weighted mean echo power spectra also show marginally significant responses in the SC sense. An approximately 4.5 standard deviation signal was obtained for Aethra. The Doppler shift of the peak is about 10 Hz higher than that predicted from the a priori trial ephemeris. Calculations are performed to determine whether this frequency offset can be reconciled dynamically with optical positions reported for Aethra.

  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. 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.

  20. Discovery and Characterization of an L5 Neptune Trojan in the Search for a New Horizons Encounter Candidate

    NASA Astrophysics Data System (ADS)

    Parker, Alex; Buie, M.; Osip, D.; Gwyn, S.; Holman, M.; Borncamp, D.; Spencer, J.; Benecchi, S.; Binzel, R.; DeMeo, F.; Fabbro, S.; Fuentes, C.; Gay, P.; Kavelaars, J.; McLeod, B.; Petit, J.; Sheppard, S.; Stern, A.; Tholen, D.; Trilling, D.; Ragozzine, D.; Wasserman, L.; Hunters, Ice

    2012-10-01

    After its encounter with Pluto in July of 2015, New Horizons will be capable of performing a course change to target a more distant Kuiper Belt Object. We are currently engaged in a search for one or more candidate Kuiper Belt Objects for New Horizons to visit. In the course of this search, we identified a new L5 Neptune Trojan. This Trojan is as bright as the largest L5 Jupiter Trojan (H 8.2), and has an inclination higher than any other known Neptune Trojan, at 29.4 degrees. We have performed numerical integrations of its orbit and confirmed that it is stably resonant for a large fraction of the age of the Solar System, making it only the second stable L5 Neptune Trojan known. Given our survey's characteristics, the detection of this object confirms that the L5 Neptune Trojans are a large, highly excited population. In addition, we have obtained its photometric colors, a first for an L5 Neptune Trojan, and confirmed that it has a moderately-red color similar to the L4 Neptune Trojan cloud, which are similar to the Jupiter Trojan colors. In late 2013 this object passes within approximately 1.2 AU of the New Horizons spacecraft, and may be within the limits of detection of the LORRI imager. We present the discovery circumstances and our characterization of this Neptune Trojan, and its implications for the Neptune Trojan population. We also introduce a novel statistical technique for debiasing the Neptune Trojan orbit distribution, and compare these debiased orbit distributions to those of other minor planet populations.

  1. Delivery of Nano-Tethered Therapies to Brain Metastases of Primary Breast Cancer Using a Cellular Trojan Horse

    DTIC Science & Technology

    2014-10-01

    REFERENCES: 1. M.-R. Choi et al., Delivery of nanoparticles to brain metastases of breast cancer using a cellular Trojan horse. Cancer Nanotechnol. 3...subtype”, Ann Oncol, 2010, 21: 942– 948. [2] Mi-Ran Choi, et al., “Delivery of nanoparticles to brain metastases of breast cancer using a cellular Trojan...horse”, Cancer Nano, 2012; 3: 47- 54. [3] Mi-Ran Choi, et al., “A cellular Trojan Horse for delivery of therapeutic nanoparticles into tumors

  2. A new method based on the subpixel Gaussian model for accurate estimation of asteroid coordinates

    NASA Astrophysics Data System (ADS)

    Savanevych, V. E.; Briukhovetskyi, O. B.; Sokovikova, N. S.; Bezkrovny, M. M.; Vavilova, I. B.; Ivashchenko, Yu. M.; Elenin, L. V.; Khlamov, S. V.; Movsesian, Ia. S.; Dashkova, A. M.; Pogorelov, A. V.

    2015-08-01

    We describe a new iteration method to estimate asteroid coordinates, based on a subpixel Gaussian model of the discrete object image. The method operates by continuous parameters (asteroid coordinates) in a discrete observational space (the set of pixel potentials) of the CCD frame. In this model, the kind of coordinate distribution of the photons hitting a pixel of the CCD frame is known a priori, while the associated parameters are determined from a real digital object image. The method that is developed, which is flexible in adapting to any form of object image, has a high measurement accuracy along with a low calculating complexity, due to the maximum-likelihood procedure that is implemented to obtain the best fit instead of a least-squares method and Levenberg-Marquardt algorithm for minimization of the quadratic form. Since 2010, the method has been tested as the basis of our Collection Light Technology (COLITEC) software, which has been installed at several observatories across the world with the aim of the automatic discovery of asteroids and comets in sets of CCD frames. As a result, four comets (C/2010 X1 (Elenin), P/2011 NO1(Elenin), C/2012 S1 (ISON) and P/2013 V3 (Nevski)) as well as more than 1500 small Solar system bodies (including five near-Earth objects (NEOs), 21 Trojan asteroids of Jupiter and one Centaur object) have been discovered. We discuss these results, which allowed us to compare the accuracy parameters of the new method and confirm its efficiency. In 2014, the COLITEC software was recommended to all members of the Gaia-FUN-SSO network for analysing observations as a tool to detect faint moving objects in frames.

  3. 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 ...

  4. 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

  5. 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 ...

  6. 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.

  7. 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

  8. System-level protection and hardware Trojan detection using weighted voting.

    PubMed

    Amin, Hany A M; Alkabani, Yousra; Selim, Gamal M I

    2014-07-01

    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.

  9. 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.

  10. Surface heterogeneity of small asteroids

    NASA Astrophysics Data System (ADS)

    Sasaki, Sho

    A rubble pile model of asteroid origin would predict averaged rather homogeneous surface of an asteroid. Previous spacecraft observations (mostly S-type asteroids) did not show large color/albedo variation on the surface. Vesta would be exceptional since HST observation suggested that its surface should be heterogeneous due to the impact excavation of the interior. As for a young asteroid (832) Karin (age being 5Ma), Sasaki et al. (2004) detected variation of infrared spectra which could be explained by the difference of the space weathering degree. They discussed the possibility of the survival of the old surface. However, the variation was not confirmed by later observation (Chapman et al., 2007; Vernazza et al., 2007). Recent observation of a small (550m) asteroid Itokawa by Hayabusa spacecraft revealed that Itokawa is heterogeneous in color and albedo although the overall rocky structure is considered as a rubble pile (Saito et al., 2006). The color difference can be explained by the difference of weathering degree (Ishiguro et al., 2008). The heterogeneity could be explained by mass movement caused by rapid rotation from YORP effect (Scheeres et al., 2007) or seismic shaking (Sasaki, 2006). Probably small silicate asteroids without significant regolith could have heterogeneous in color and albedo. On large asteroids (˜ a few 10km), regolith reaccumulation should have covered the underlying heterogeneity. References: Chapman, C. R. et al (2007) Icarus, 191, 323-329 Ishiguro, M. et al. (2008) MAPS, in press. Saito, J. et al. (2006) Science, 312, 1341-1344 Sasaki, S. (2006) in Spacecraft Reconnaissance of Asteroid and Comet Interiors Sasaki, T. et al (2004) Astrophys. J. 615, L161-L164 Scheeres, D. J. (2007) Icarus 188, 425-429 Vernazza, P. et al. (2007) Icarus 191, 330-336.

  11. 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.

  12. 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.

  13. Cellinoid Shape Model for Asteroids

    NASA Astrophysics Data System (ADS)

    Lu, Xiaoping; Zhao, Haibin; You, Zhong

    2014-08-01

    The ellipsoid shape model plays an important role in physical research on asteroids. However, its symmetric structure cannot practically simulate real asteroids. This article applies a general shape model, named the cellinoid, instead of the ellipsoid model to simulate the asymmetric shape of asteroids. The cellinoid shape model consists of eight octants of ellipsoids having different semi-axes, with the constraint that adjacent octants must have two equal semi-axes in common. Totally, the shape of the cellinoid model is controlled by six parameters, not three as in the case of the shape of the ellipsoid. Using this shape model, the brightness of asteroids observed from the Earth can be fitted numerically by the surface triangularization of the cellinoid. The Levenberg-Marquardt algorithm is also employed here to solve a nonlinear minimization problem. Owing to the asymmetric shape of the cellinoid, the physical parameters of asteroids, such as the rotation period and pole orientation, can be fitted more accurately than in the case of the ellipsoid model. Finally, this is confirmed numerically by applying the shape to both synthetic light curves and real light curves of asteroids. Additionally, the center of mass and moment of inertia of the cellinoid are analyzed explicitly.

  14. 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.

  15. 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.

  16. 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.

  17. Supramolecular "Trojan Horse" for Nuclear Delivery of Dual Anticancer Drugs.

    PubMed

    Cai, Yanbin; Shen, Haosheng; Zhan, Jie; Lin, Mingliang; Dai, Liuhan; Ren, Chunhua; Shi, Yang; Liu, Jianfeng; Gao, Jie; Yang, Zhimou

    2017-03-01

    Nuclear delivery and accumulation are very important for many anticancer drugs that interact with DNA or its associated enzymes in the nucleus. However, it is very difficult for neutrally and negatively charged anticancer drugs such as 10-hydroxycamptothecine (HCPT). Here we report a simple strategy to construct supramolecular nanomedicines for nuclear delivery of dual synergistic anticancer drugs. Our strategy utilizes the coassembly of a negatively charged HCPT-peptide amphiphile and the positively charged cisplatin. The resulting nanomaterials behave as the "Trojan Horse" that transported soldiers (anticancer drugs) across the walls of the castle (cell and nucleus membranes). Therefore, they show improved inhibition capacity to cancer cells including the drug resistant cancer cell and promote the synergistic tumor suppression property in vivo. We envision that our strategy of constructing nanomaterials by metal chelation would offer new opportunities to develop nanomedicines for combination chemotherapy.

  18. Applications of the Trojan Horse method in nuclear astrophysics

    NASA Astrophysics Data System (ADS)

    Spitaleri, Claudio

    2015-02-01

    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.

  19. Refining the asteroid taxonomy by polarimetric observations

    NASA Astrophysics Data System (ADS)

    Belskaya, I. N.; Fornasier, S.; Tozzi, G. P.; Gil-Hutton, R.; Cellino, A.; Antonyuk, K.; Krugly, Yu. N.; Dovgopol, A. N.; Faggi, S.

    2017-03-01

    We present new results of polarimetric observations of 15 main belt asteroids of different composition. By merging new and published data we determined polarimetric parameters characterizing individual asteroids and mean values of the same parameters characterizing different taxonomic classes. The majority of asteroids show polarimetric phase curves close to the average curve of the corresponding class. We show that using polarimetric data it is possible to refine asteroid taxonomy and derive a polarimetric classification for 283 main belt asteroids. Polarimetric observations of asteroid (21) Lutetia are found to exhibit possible variations of the position angle of the polarization plane over the surface.

  20. Origin and dynamical evolution of Neptune Trojans - I. Formation and planetary migration

    NASA Astrophysics Data System (ADS)

    Lykawka, P. S.; Horner, J.; Jones, B. W.; Mukai, T.

    2009-10-01

    We present the results of detailed dynamical simulations of the effect of the migration of the four giant planets on both the transport of pre-formed Neptune Trojans and the capture of new Trojans from a trans-Neptunian disc. The cloud of pre-formed Trojans consisted of thousands of massless particles placed on dynamically cold orbits around Neptune's L4 and L5 Lagrange points, while the trans-Neptunian disc contained tens of thousands of such particles spread on dynamically cold orbits between the initial and final locations of Neptune. Through the comparison of the results with the previous work on the known Neptunian Trojans, we find that scenarios involving the slow migration of Neptune over a large distance (50 Myr to migrate from 18.1 au to its current location, using an exponential-folding time of τ = 10 Myr) provide the best match to the properties of the known Trojans. Scenarios with faster migration (5Myr, with τ = 1Myr), and those in which Neptune migrates from 23.1 au to its current location, fail to adequately reproduce the current-day Trojan population. Scenarios which avoid disruptive perturbation events between Uranus and Neptune fail to yield any significant excitation of pre-formed Trojans (transported with efficiencies between 30 and 98 per cent whilst maintaining the dynamically cold nature of these objects - e < 0.1, i < 5°). Conversely, scenarios with periods of strong Uranus-Neptune perturbation lead to the almost complete loss of such pre-formed objects. In these cases, a small fraction (~0.15 per cent) of these escaped objects are later recaptured as Trojans prior to the end of migration, with a wide range of eccentricities (<0.35) and inclinations (<40°). In all scenarios (including those with such disruptive interaction between Uranus and Neptune), the capture of objects from the trans-Neptunian disc (through which Neptune migrates) is achieved with efficiencies between ~0.1 and ~1 per cent. The captured Trojans display a wide range

  1. 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.

  2. 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 El