Performance Evaluation of an Expanded Range XIPS Ion Thruster System for NASA Science Missions

NASA Technical Reports Server (NTRS)

Oh, David Y.; Goebel, Dan M.

2006-01-01

This paper examines the benefit that a solar electric propulsion (SEP) system based on the 5 kW Xenon Ion Propulsion System (XIPS) could have for NASA's Discovery class deep space missions. The relative cost and performance of the commercial heritage XIPS system is compared to NSTAR ion thruster based systems on three Discovery class reference missions: 1) a Near Earth Asteroid Sample Return, 2) a Comet Rendezvous and 3) a Main Belt Asteroid Rendezvous. It is found that systems utilizing a single operating XIPS thruster provides significant performance advantages over a single operating NSTAR thruster. In fact, XIPS performs as well as systems utilizing two operating NSTAR thrusters, and still costs less than the NSTAR system with a single operating thruster. This makes XIPS based SEP a competitive and attractive candidate for Discovery class science missions.

Solar Electric Propulsion for Primitive Body Science Missions

NASA Technical Reports Server (NTRS)

Witzberger, Kevin E.

2006-01-01

This paper describes work that assesses the performance of solar electric propulsion (SEP) for three different primitive body science missions: 1) Comet Rendezvous 2) Comet Surface Sample Return (CSSR), and 3) a Trojan asteroid/Centaur object Reconnaissance Flyby. Each of these missions launches from Earth between 2010 and 2016. Beginning-of-life (BOL) solar array power (referenced at 1 A.U.) varies from 10 to 18 kW. Launch vehicle selections range from a Delta II to a Delta IV medium-class. The primary figure of merit (FOM) is net delivered mass (NDM). This analysis considers the effects of imposing various mission constraints on the Comet Rendezvous and CSSR missions. Specifically, the Comet Rendezvous mission analysis examines an arrival date constraint with a launch year variation, whereas the CSSR mission analysis investigates an Earth entry velocity constraint commensurate with past and current missions. Additionally, the CSSR mission analysis establishes NASA's New Frontiers (NF) Design Reference Mission (DRM) in order to evaluate current and future SEP technologies. The results show that transfer times range from 5 to 9 years (depending on the mission). More importantly, the spacecraft's primary propulsion system performs an average 5-degree plane change on the return leg of the CSSR mission to meet the previously mentioned Earth entry velocity constraint. Consequently, these analyses show that SEP technologies that have higher thrust-to-power ratios can: 1) reduce flight time, and 2) change planes more efficiently.

Coordinated Radio, Electron, and Waves Experiment (CREWE) for the NASA Comet Rendezvous and Asteroid Flyby (CRAF) instrument

NASA Technical Reports Server (NTRS)

Scudder, Jack D.

1992-01-01

The Coordinated Radio, Electron, and Waves Experiment (CREWE) was designed to determine density, bulk velocity and temperature of the electrons for the NASA Comet Rendezvous and Asteroid Flyby Spacecraft, to define the MHD-SW IMF flow configuration; to clarify the role of impact ionization processes, to comment on the importance of anomalous ionization phenomena (via wave particle processes), to quantify the importance of wave turbulence in the cometary interaction, to establish the importance of photoionization via the presence of characteristic lines in a structured energy spectrum, to infer the presence and grain size of significant ambient dust column density, to search for the theoretically suggested 'impenetrable' contact surface, and to quantify the flow of heat (in the likelihood that no surface exists) that will penetrate very deep into the atmosphere supplying a good deal of heat via impact and charge exchange ionization. This final report provides an instrument description, instrument test plans, list of deliverables/schedule, flight and support equipment and software schedule, CREWE accommodation issues, resource requirements, status of major contracts, an explanation of the non-NASA funded efforts, status of EIP and IM plan, descope options, and Brinton questions.

Deep space network: Mission support requirements

NASA Technical Reports Server (NTRS)

1991-01-01

The purpose is to provide NASA and Jet Propulsion Laboratory management with a concise summary of information concerning the forecasting of the necessary support and requirements for missions described here, including the Earth Radiation Budget Experiment, the Cosmic Background Explorer, the Comet Rendezvous Asteroid Flyby, the Cassini, and the Dynamics Explorer-1. A brief description of various missions along with specific support requirements for each are given.

Basic targeting strategies for rendezvous and flyby missions to the near-Earth asteroids

NASA Astrophysics Data System (ADS)

Perozzi, Ettore; Rossi, Alessandro; Valsecchi, Giovanni B.

2001-01-01

Missions to asteroids and comets are becoming increasingly feasible both from a technical and a financial point of view. In particular, those directed towards the Near-Earth Asteroids have proven suitable for a low-cost approach, thus attracting the major space agencies as well as private companies. The choice of a suitable target involves both scientific relevance and mission design considerations, being often a difficult task to accomplish due to the limited energy budget at disposal. The aim of this paper is to provide an approach to basic trajectory design which allows to account for both aspects of the problem, taking into account scientific and technical information. A global characterization of the Near-Earth Asteroids population carried out on the basis of their dynamics, physical properties and flight dynamics considerations, allows to identify a group of candidates which satisfy both, the scientific and engineering requirements. The feasibility of rendezvous and flyby missions towards them is then discussed and the possibility of repeated encounters with the same object is investigated, as an intermediate scenario. Within this framework, the capability of present and near future launch and propulsion systems for interplanetary missions is also addressed.

Outward to the Beginning: the CRAF and Cassini Missions of the Mariner Mark 2 Program

NASA Technical Reports Server (NTRS)

1988-01-01

Two successive journeys will soon offer a perspective on the origin of the solar system and perhaps provide clues on the origin of life as well. The missions, the Comet Rendezvous Asteroid Flyby (CRAF) and Cassini (the Saturn orbiter/Titan probe), combine to form the first initiative of the Mariner Mark 2 program, a series of planetary missions whose common objective is to explore primitive bodies and the outer solar system, toward the ultimate goal of understanding the nature of our origins. Cassini and CRAF are exciting planetary missions. The objectives that they share, the region of the solar system in which comets, asteroids, and the Saturnian system have evolved and now reside, and the spacecraft that will carry both sets of experiments to their targets in the outer solar system are described.

Study of a comet rendezvous mission. Volume 2: Appendices

NASA Technical Reports Server (NTRS)

1972-01-01

Appendices to the comet Encke rendezvous mission consider relative positions of comet, earth and sun; viewing condition for Encke; detection of Taurid meteor streams; ephemeris of comet Encke; microwave and optical techniques in rendezvous mission; approach instruments; electrostatic equilibrium of ion engine spacecraft; comet flyby data for rendezvous spacecraft assembly; observations of P/Encke extracted from a compilation; and summary of technical innovations.

A Reconfigurable Testbed Environment for Spacecraft Autonomy

NASA Technical Reports Server (NTRS)

Biesiadecki, Jeffrey; Jain, Abhinandan

1996-01-01

A key goal of NASA's New Millennium Program is the development of technology for increased spacecraft on-board autonomy. Achievement of this objective requires the development of a new class of ground-based automony testbeds that can enable the low-cost and rapid design, test, and integration of the spacecraft autonomy software. This paper describes the development of an Autonomy Testbed Environment (ATBE) for the NMP Deep Space I comet/asteroid rendezvous mission.

A new terminal guidance sensor system for asteroid intercept or rendezvous missions

NASA Astrophysics Data System (ADS)

Lyzhoft, Joshua; Basart, John; Wie, Bong

2016-02-01

This paper presents the initial conceptual study results of a new terminal guidance sensor system for asteroid intercept or rendezvous missions, which explores the use of visual, infrared, and radar devices. As was demonstrated by NASA's Deep Impact mission, visual cameras can be effectively utilized for hypervelocity intercept terminal guidance for a 5 kilometer target. Other systems such as Raytheon's EKV (Exoatmospheric Kill Vehicle) employ a different scheme that utilizes infrared target information to intercept ballistic missiles. Another example that uses infrared information is the NEOWISE telescope, which is used for asteroid detection and tracking. This paper describes the signal-to-noise ratio estimation problem for infrared sensors, minimum and maximum range of detection, and computational validation using GPU accelerated simulations. Small targets (50-100 m in diameter) are considered, and scaled polyhedron models of known objects, such as the Rosetta mission's Comet 67P/Churyumov-Gerasimenko, 101,955 Bennu, target of the OSIRIS-REx mission, and asteroid 433 Eros, are utilized. A parallelized ray tracing algorithm to simulate realistic surface-to-surface shadowing of a given celestial body is developed. By using the simulated models and parameters given from the formulation of the different sensors, impact mission scenarios are used to verify the feasibility for intercepting a small target.

Comet rendezvous mission study

NASA Technical Reports Server (NTRS)

Friedlander, A. L.; Wells, W. C.

1971-01-01

Four periodic comets with perihelia between 1980 and 1986 (Encke, d'Arrest, Kipff, and Halley) are used as candidates for the comet rendezvous mission study. All these comet apparitions are especially favorable for rendezvous missions, because of early earth-based comet recovery, good opportunities to view their activity from earth, and reasonable launch vehicle and trajectory requirements for nominal payloads.

The Hitchhiker's Guide to the Outer Solar System

NASA Technical Reports Server (NTRS)

Ono, Masahiro; Quadrelli, Marco; Lantoine, Gregory; Backes, Paul; Lopez Ortega, Alejandro; Grip, Havard; Yen, Chen-Wan; Jewitt, David

2015-01-01

We propose a novel deep space propulsion method called the Comet Hitchhiker. The concept is to perform momentum exchange with small bodies (i.e., asteroid and comet) using an extendable/retrievable tether and a harpoon. Unlike previously proposed tethered fly-by, the use of extendable tether enables to change the relative speed with a target. Hence Hitchhiker would be a prospective means of providing orbit insertion deltaV, particularly for rendezvous missions to small bodies in the outer Solar System such as Kuiper belt objects and Centaurs, which are not easily manageable with chemical propulsion or solar electric propulsion. Furthermore, by applying regenerative brake during a hitchhike maneuver, a Hitchhiker can harvest energy. The stored energy can be used to make a departure from the target by quickly retrieving the tether, which we call a inverse hitchhike maneuver. By repeating hitchhike and inverse Hitchhike maneuvers, a Hitchhiker could perform a mission to rendezvous with multiple targets efficiently, which we call a multi-hitchhike mission. We derive the basic equation of Hitchhiker, namely the Space Hitchhike Equation, which relates the specific strength and mass fraction of tether to achievable ?V. We then perform detailed feasibility analysis through finite element simulations of tether as well as hypervelocity impact simulations of the harpoon using the Adaptive Mesh Refinement Objected-oriented C++ (AMROC) algorithm. The analysis results suggest that a hitchhike maneuver with deltaV = approximately 1.5km/s is feasible with flight proven materials such as Kevlar/Zylon tether and tungsten harpoon. A carbon nanotube tether, combined with diamond harpoon, would enable approximately 10 km/s hitchhike maneuver. Finally, we present two particular mission scenarios for Hitchhiker: Pluto rendezvous and a multi-hitchhike mission to the Themis family asteroids in the main belt.

Software simulations of the detection of rapidly moving asteroids by a charge-coupled device

NASA Astrophysics Data System (ADS)

McMillan, R. S.; Stoll, C. P.

1982-10-01

A rendezvous of an unmanned probe to an earth-approaching asteroid has been given a high priority in the planning of interplanetary missions for the 1990s. Even without a space mission, much could be learned about the history of asteroids and comet nuclei if more information were available concerning asteroids with orbits which cross or approach the orbit of earth. It is estimated that the total number of earth-crossers accessible to ground-based survey telescopes should be approximately 1000. However, in connection with the small size and rapid angular motion expected of many of these objects an average of only one object is discovered per year. Attention is given to the development of the software necessary to distinguish such rapidly moving asteroids from stars and noise in continuously scanned CCD exposures of the night sky. Model and input parameters are considered along with detector sensitivity, aspects of minimum detectable displacement, and the point-spread function of the CCD.

Mars Geochemical Instrument (MarGI): An instrument for the analysis of the Martian surface and the search for evidence of life

NASA Technical Reports Server (NTRS)

Kojiro, Daniel R.; Mancinelli, Rocco; Martin, Joe; Holland, Paul M.; Stimac, Robert M.; Kaye, William J.

2005-01-01

The Mars Geochemical Instrument, MarGI, was developed to provide a comprehensive analysis of the rocks and surface material on Mars. The instrument combines Differential Thermal Analysis (DTA) with miniature Gas Chromatography-Ion Mobility Spectrometry (GC-IMS) to identify minerals, the presence and state of water, and organic compounds. Miniature pyrolysis ovens are used to both, conduct DTA analysis of soil or crushed rocks samples, and pyrolyze the samples at temperatures up to 1000 degrees C for GC-IMS analysis of the released gases. This combination of analytical processes and techniques, which can characterize the mineralogy of the rocks and soil, and identify and quantify volatiles released during pyrolysis, has applications across a wide range of target sites including comets, planets, asteroids, and moons such as Titan and Europa. The MarGI analytical approach evolved from the Cometary Ice and Dust Experiment (CIDEX) selected to fly on the Comet Rendezvous Asteroid Flyby Mission (CRAF).

E-type asteroid (2867) Steins as imaged by OSIRIS on board Rosetta.

PubMed

Keller, H U; Barbieri, C; Koschny, D; Lamy, P; Rickman, H; Rodrigo, R; Sierks, H; A'Hearn, M F; Angrilli, F; Barucci, M A; Bertaux, J-L; Cremonese, G; Da Deppo, V; Davidsson, B; De Cecco, M; Debei, S; Fornasier, S; Fulle, M; Groussin, O; Gutierrez, P J; Hviid, S F; Ip, W-H; Jorda, L; Knollenberg, J; Kramm, J R; Kührt, E; Küppers, M; Lara, L-M; Lazzarin, M; Lopez Moreno, J; Marzari, F; Michalik, H; Naletto, G; Sabau, L; Thomas, N; Wenzel, K-P; Bertini, I; Besse, S; Ferri, F; Kaasalainen, M; Lowry, S; Marchi, S; Mottola, S; Sabolo, W; Schröder, S E; Spjuth, S; Vernazza, P

2010-01-08

The European Space Agency's Rosetta mission encountered the main-belt asteroid (2867) Steins while on its way to rendezvous with comet 67P/Churyumov-Gerasimenko. Images taken with the OSIRIS (optical, spectroscopic, and infrared remote( )imaging system) cameras on board Rosetta show that Steins is an oblate body with an effective spherical diameter of 5.3 kilometers. Its surface does not show color variations. The morphology of Steins is dominated by linear faults and a large 2.1-kilometer-diameter crater near its south pole. Crater counts reveal a distinct lack of small craters. Steins is not solid rock but a rubble pile and has a conical appearance that is probably the result of reshaping due to Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) spin-up. The OSIRIS images constitute direct evidence for the YORP effect on a main-belt asteroid.

E-Type Asteroid (2867) Steins as Imaged by OSIRIS on Board Rosetta

NASA Astrophysics Data System (ADS)

Keller, H. U.; Barbieri, C.; Koschny, D.; Lamy, P.; Rickman, H.; Rodrigo, R.; Sierks, H.; A'Hearn, M. F.; Angrilli, F.; Barucci, M. A.; Bertaux, J.-L.; Cremonese, G.; Da Deppo, V.; Davidsson, B.; De Cecco, M.; Debei, S.; Fornasier, S.; Fulle, M.; Groussin, O.; Gutierrez, P. J.; Hviid, S. F.; Ip, W.-H.; Jorda, L.; Knollenberg, J.; Kramm, J. R.; Kührt, E.; Küppers, M.; Lara, L.-M.; Lazzarin, M.; Moreno, J. Lopez; Marzari, F.; Michalik, H.; Naletto, G.; Sabau, L.; Thomas, N.; Wenzel, K.-P.; Bertini, I.; Besse, S.; Ferri, F.; Kaasalainen, M.; Lowry, S.; Marchi, S.; Mottola, S.; Sabolo, W.; Schröder, S. E.; Spjuth, S.; Vernazza, P.

2010-01-01

The European Space Agency’s Rosetta mission encountered the main-belt asteroid (2867) Steins while on its way to rendezvous with comet 67P/Churyumov-Gerasimenko. Images taken with the OSIRIS (optical, spectroscopic, and infrared remote imaging system) cameras on board Rosetta show that Steins is an oblate body with an effective spherical diameter of 5.3 kilometers. Its surface does not show color variations. The morphology of Steins is dominated by linear faults and a large 2.1-kilometer-diameter crater near its south pole. Crater counts reveal a distinct lack of small craters. Steins is not solid rock but a rubble pile and has a conical appearance that is probably the result of reshaping due to Yarkovsky-O’Keefe-Radzievskii-Paddack (YORP) spin-up. The OSIRIS images constitute direct evidence for the YORP effect on a main-belt asteroid.

The design of transfer trajectory for Ivar asteroid exploration mission

NASA Astrophysics Data System (ADS)

Qiao, Dong; Cui, Hutao; Cui, Pingyuan

2009-12-01

An impending demand for exploring the small bodies, such as the comets and the asteroids, envisioned the Chinese Deep Space exploration mission to the Near Earth asteroid Ivar. A design and optimal method of transfer trajectory for asteroid Ivar is discussed in this paper. The transfer trajectory for rendezvous with asteroid Ivar is designed by means of Earth gravity assist with deep space maneuver (Delta-VEGA) technology. A Delta-VEGA transfer trajectory is realized by several trajectory segments, which connect the deep space maneuver and swingby point. Each trajectory segment is found by solving Lambert problem. Through adjusting deep maneuver and arrival time, the match condition of swingby is satisfied. To reduce the total mission velocity increments further, a procedure is developed which minimizes total velocity increments for this scheme of transfer trajectory for asteroid Ivar. The trajectory optimization problem is solved with a quasi-Newton algorithm utilizing analytic first derivatives, which are derived from the transversality conditions associated with the optimization formulation and primer vector theory. The simulation results show the scheme for transfer trajectory causes C3 and total velocity increments decrease of 48.80% and 13.20%, respectively.

Multiple main-belt asteroid mission options for a Mariner Mark II spacecraft

NASA Astrophysics Data System (ADS)

Sauer, Carl G., Jr.; Yen, Chen-Wan L.

This paper presents the trajectory options available for a MMII spacecraft mission to asteroids and introduces systematic methods of uncovering attractive mission opportunities. The analysis presented considers multiple synchronous gravity assists of Mars and introduces a terminal resonant or phasing orbit; a concept useful for both increasing the number of asteroid rendezvous targets attainable during a launch opportunity, and also in increasing the number of potential asteroid flybys. Systematic examinations of the requirements for superior asteroidal alignments are made and a comprehensive set of asteroid rendezvous opportunities for the 1998 to 2010 period are presented. Examples of candidate missions involving one or more rendezvous and several flybys are also presented.

Multiple main-belt asteroid mission options for a Mariner Mark II spacecraft

NASA Technical Reports Server (NTRS)

Sauer, Carl G., Jr.; Yen, Chen-Wan L.

1990-01-01

This paper presents the trajectory options available for a MMII spacecraft mission to asteroids and introduces systematic methods of uncovering attractive mission opportunities. The analysis presented considers multiple synchronous gravity assists of Mars and introduces a terminal resonant or phasing orbit; a concept useful for both increasing the number of asteroid rendezvous targets attainable during a launch opportunity, and also in increasing the number of potential asteroid flybys. Systematic examinations of the requirements for superior asteroidal alignments are made and a comprehensive set of asteroid rendezvous opportunities for the 1998 to 2010 period are presented. Examples of candidate missions involving one or more rendezvous and several flybys are also presented.

CORSAIR (COmet Rendezvous, Sample Acquisition, Investigation, and Return): A New Frontiers Mission Concept to Collect Samples from a Comet and Return Them to Earth for Study

NASA Astrophysics Data System (ADS)

Sandford, S. A.; Chabot, N. L.; Dello Russo, N.; Leary, J. C.; Reynolds, E. L.; Weaver, H. A.; Wooden, D. H.

2017-07-01

CORSAIR (COmet Rendezvous, Sample Acquisition, Investigation, and Return) is a mission concept submitted in response to NASA's New Frontiers 4 call. CORSAIR's proposed mission is to return comet nucleus samples to Earth for detailed analysis.

Enhanced Gravity Tractor Technique for Planetary Defense

NASA Technical Reports Server (NTRS)

Mazanek, Daniel D.; Reeves, David M.; Hopkins, Joshua B.; Wade, Darren W.; Tantardini, Marco; Shen, Haijun

2015-01-01

Given sufficient warning time, Earth-impacting asteroids and comets can be deflected with a variety of different "slow push/pull" techniques. The gravity tractor is one technique that uses the gravitational attraction of a rendezvous spacecraft to the impactor and a low-thrust, high-efficiency propulsion system to provide a gradual velocity change and alter its trajectory. An innovation to this technique, known as the Enhanced Gravity Tractor (EGT), uses mass collected in-situ to augment the mass of the spacecraft, thereby greatly increasing the gravitational force between the objects. The collected material can be a single boulder, multiple boulders, regolith or a combination of different sources. The collected mass would likely range from tens to hundreds of metric tons depending on the size of the impactor and warning time available. Depending on the propulsion system's capability and the mass collected, the EGT approach can reduce the deflection times by a factor of 10 to 50 or more, thus reducing the deflection times of several decades to years or less and overcoming the main criticism of the traditional gravity tractor approach. Additionally, multiple spacecraft can orbit the target in formation to provide the necessary velocity change and further reduce the time needed by the EGT technique to divert hazardous asteroids and comets. The robotic segment of NASA's Asteroid Redirect Mission (ARM) will collect a multi-ton boulder from the surface of a large Near-Earth Asteroid (NEA) and will provide the first ever demonstration of the EGT technique and validate one method of collecting in-situ mass on an asteroid of hazardous size.

Main-belt asteroid exploration - Mission options for the 1990s

NASA Technical Reports Server (NTRS)

Yen, Chen-Wan L.

1989-01-01

An extensive investigation of the ways to rendezvous with diverse groups of asteroids residing between 2.0 and 5.0 AU is made, and the extent of achievable missions using the STS upper-stage launch vehicles (IUS 2-Stage/Star-48 or NASA Centaur) is examined. With judicious use of earth, Mars, and Jupiter gravity assists, rendezvous with some asteroids in all regions of space is possible. It is also shown that the STS upper stages are capable of carrying out missions beyond a single rendezvous, namely with several flybys and/or multiple rendezvous.

The Rosetta mission orbiter science overview: the comet phase

PubMed Central

Altobelli, N.; Buratti, B. J.; Choukroun, M.

2017-01-01

The international Rosetta mission was launched in 2004 and consists of the orbiter spacecraft Rosetta and the lander Philae. The aim of the mission is to map the comet 67P/Churyumov–Gerasimenko by remote sensing, and to examine its environment in situ and its evolution in the inner Solar System. Rosetta was the first spacecraft to rendezvous with and orbit a comet, accompanying it as it passes through the inner Solar System, and to deploy a lander, Philae, and perform in situ science on the comet's surface. The primary goals of the mission were to: characterize the comet's nucleus; examine the chemical, mineralogical and isotopic composition of volatiles and refractories; examine the physical properties and interrelation of volatiles and refractories in a cometary nucleus; study the development of cometary activity and the processes in the surface layer of the nucleus and in the coma; detail the origin of comets, the relationship between cometary and interstellar material and the implications for the origin of the Solar System; and characterize asteroids 2867 Steins and 21 Lutetia. This paper presents a summary of mission operations and science, focusing on the Rosetta orbiter component of the mission during its comet phase, from early 2014 up to September 2016. This article is part of the themed issue ‘Cometary science after Rosetta’. PMID:28554981

Exploring Asteroid Interiors: The Deep Interior Mission Concept

NASA Technical Reports Server (NTRS)

Asphaug, E.; Belton, M. J. S.; Cangahuala, A.; Keith, L.; Klaasen, K.; McFadden, L.; Neumann, G.; Ostro, S. J.; Reinert, R.; Safaeinili, A.

2003-01-01

Deep Interior is a mission to determine the geophysical properties of near-Earth objects, including the first volumetric image of the interior of an asteroid. Radio reflection tomography will image the 3D distribution of complex dielectric properties within the 1 km rendezvous target and hence map structural, density or compositional variations. Laser altimetry and visible imaging will provide high-resolution surface topography. Smart surface pods culminating in blast experiments, imaged by the high frame rate camera and scanned by lidar, will characterize active mechanical behavior and structure of surface materials, expose unweathered surface for NIR analysis, and may enable some characterization of bulk seismic response. Multiple flybys en route to this target will characterize a diversity of asteroids, probing their interiors with non-tomographic radar reflectance experiments. Deep Interior is a natural follow-up to the NEARShoemaker mission and will provide essential guidance for future in situ asteroid and comet exploration. While our goal is to learn the interior geology of small bodies and how their surfaces behave, the resulting science will enable pragmatic technologies required of hazard mitigation and resource utilization.

Performance of advanced missions using fusion propulsion

NASA Technical Reports Server (NTRS)

Friedlander, Alan; Mcadams, Jim; Schulze, Norm

1989-01-01

A quantitive evaluation of the premise that nuclear fusion propulsion offers benefits as compared to other propulsion technologies for carrying out a program of advanced exploration of the solar system and beyond is presented. Using a simplified analytical model of trajectory performance, numerical results of mass requirements versus trip time are given for robotic missions beyond the solar system that include flyby and rendezvous with the Oort cloud of comets and with the star system Alpha Centauri. Round trip missions within the solar system, including robotic sample returns from the outer planet moons and multiple asteroid targets, and manned Mars exploration are also described.

Advanced flight computers for planetary exploration

NASA Technical Reports Server (NTRS)

Stephenson, R. Rhoads

1988-01-01

Research concerning flight computers for use on interplanetary probes is reviewed. The history of these computers from the Viking mission to the present is outlined. The differences between ground commercial computers and computers for planetary exploration are listed. The development of a computer for the Mariner Mark II comet rendezvous asteroid flyby mission is described. Various aspects of recently developed computer systems are examined, including the Max real time, embedded computer, a hypercube distributed supercomputer, a SAR data processor, a processor for the High Resolution IR Imaging Spectrometer, and a robotic vision multiresolution pyramid machine for processsing images obtained by a Mars Rover.

Deep Space 1 Using its Ion Engine (Artist's Concept)

NASA Technical Reports Server (NTRS)

2003-01-01

NASA's New Millennium Deep Space 1 spacecraft approaching the comet 19P/Borrelly. With its primary mission to serve as a technology demonstrator--testing ion propulsion and 11 other advanced technologies--successfully completed in September 1999, Deep Space 1 is now headed for a risky, exciting rendezvous with Comet Borrelly. NASA extended the mission, taking advantage of the ion propulsion and other systems to target the daring encounter with the comet in September 2001. Once a sci-fi dream, the ion propulsion engine has powered the spacecraft for over 12,000 hours. Another onboard experiment includes software that tracks celestial bodies so the spacecraft can make its own navigation decisions without the intervention of ground controllers. The first flight in NASA's New Millennium Program, Deep Space 1 was launched October 24, 1998 aboard a Boeing Delta 7326 rocket from Cape Canaveral Air Station, FL. Deep Space 1 successfully completed and exceeded its mission objectives in July 1999 and flew by a near-Earth asteroid, Braille (1992 KD), in September 1999.

Guidance, navigation, and control study for a solar electric propulsion spacecraft

NASA Technical Reports Server (NTRS)

Kluever, Craig A.

1995-01-01

A preliminary investigation of a lunar-comet rendezvous mission using a solar electric propulsion (SEP) spacecraft was performed in two phases.The first phase involved exploration of the moon and the second involved rendezvous with a comet. The initial phase began with a chemical propulsion translunar injection and chemical insertion into a lunar orbit, followed by a low thrust SEP transfer to a circular, polar, low-lunar orbit. After collecting scientific data at the moon, the SEP spacecraft performed a spiral lunar escape maneuver to begin the interplanetary leg of the mission. After escape from the Earth-moon system, the SEP spacecraft maneuvered in interplanetary space and performed a rendezvous with a comet.The immediate goal of this study was to demonstrate the feasibility of using a low-thrust SEP spacecraft for orbit transfer to both the moon and a comet. Another primary goal was to develop a computer optimization code which would be robust enough to obtain minimum-fuel rendezvous trajectories for a wide range of comets.

Rapid design and optimization of low-thrust rendezvous/interception trajectory for asteroid deflection missions

NASA Astrophysics Data System (ADS)

Li, Shuang; Zhu, Yongsheng; Wang, Yukai

2014-02-01

Asteroid deflection techniques are essential in order to protect the Earth from catastrophic impacts by hazardous asteroids. Rapid design and optimization of low-thrust rendezvous/interception trajectories is considered as one of the key technologies to successfully deflect potentially hazardous asteroids. In this paper, we address a general framework for the rapid design and optimization of low-thrust rendezvous/interception trajectories for future asteroid deflection missions. The design and optimization process includes three closely associated steps. Firstly, shape-based approaches and genetic algorithm (GA) are adopted to perform preliminary design, which provides a reasonable initial guess for subsequent accurate optimization. Secondly, Radau pseudospectral method is utilized to transcribe the low-thrust trajectory optimization problem into a discrete nonlinear programming (NLP) problem. Finally, sequential quadratic programming (SQP) is used to efficiently solve the nonlinear programming problem and obtain the optimal low-thrust rendezvous/interception trajectories. The rapid design and optimization algorithms developed in this paper are validated by three simulation cases with different performance indexes and boundary constraints.

Autonomous Onboard Science Data Analysis for Comet Missions

NASA Technical Reports Server (NTRS)

Thompson, David R.; Tran, Daniel Q.; McLaren, David; Chien, Steve A.; Bergman, Larry; Castano, Rebecca; Doyle, Richard; Estlin, Tara; Lenda, Matthew

2012-01-01

Coming years will bring several comet rendezvous missions. The Rosetta spacecraft arrives at Comet 67P/Churyumov-Gerasimenko in 2014. Subsequent rendezvous might include a mission such as the proposed Comet Hopper with multiple surface landings, as well as Comet Nucleus Sample Return (CNSR) and Coma Rendezvous and Sample Return (CRSR). These encounters will begin to shed light on a population that, despite several previous flybys, remains mysterious and poorly understood. Scientists still have little direct knowledge of interactions between the nucleus and coma, their variation across different comets or their evolution over time. Activity may change on short timescales so it is challenging to characterize with scripted data acquisition. Here we investigate automatic onboard image analysis that could act faster than round-trip light time to capture unexpected outbursts and plume activity. We describe one edge-based method for detect comet nuclei and plumes, and test the approach on an existing catalog of comet images. Finally, we quantify benefits to specific measurement objectives by simulating a basic plume monitoring campaign.

Low-energy multiple rendezvous of main belt asteroids

NASA Technical Reports Server (NTRS)

Penzo, Paul A.; Bender, David F.

1992-01-01

An approach to multiple asteroid rendezvous missions to the main belt region is proposed. In this approach key information which consists of a launch date and delta V can be generated for all possible pairs of asteroids satisfying specific constraints. This information is made available on a computer file for 1000 numbered asteroids with reasonable assumptions, limitations, and approximations to limit the computer requirements and the size of the data file.

SEP ENCKE-87 and Halley rendezvous studies and improved S/C model implementation in HILTOP

NASA Technical Reports Server (NTRS)

Horsewood, J. L.; Mann, F. I.

1978-01-01

Studies were conducted to determine the performance requirements for projected state-of-the-art SEP spacecrafts boosted by the Shuttle/IUS to perform a rendezvous with the comet Halley and a rendezvous with the comet Encke during its 1977 apparition. The spacecraft model of the standard HILTOP computer program was assumed. Numerical and graphical results summarizing the studies are presented.

Potential applications of MMC and aluminum-lithium alloys in cameras for CRAF spacecraft. [Comet Rendezvous Asteroid Flyby Mission

NASA Technical Reports Server (NTRS)

Lane, Marc; Hsieh, Cheng; Adams, Lloyd

1989-01-01

In undertaking the design of a 2000-mm focal length camera for the Mariner Mark II series of spacecraft, JPL sought novel materials with the requisite dimensional and thermal stability, outgassing and corrosion resistance, low mass, high stiffness, and moderate cost. Metal-matrix composites and Al-Li alloys have, in addition to excellent mechanical properties and low density, a suitably low coefficient of thermal expansion, high specific stiffness, and good electrical conductivity. The greatest single obstacle to application of these materials to camera structure design is noted to have been the lack of information regarding long-term dimensional stability.

The flyby of Rosetta at asteroid Šteins - mission and science operations

NASA Astrophysics Data System (ADS)

Accomazzo, Andrea; Wirth, Kristin R.; Lodiot, Sylvain; Küppers, Michael; Schwehm, Gerhard

2010-07-01

The international Rosetta mission, a cornerstone mission of the european space agency scientific Programme, was launched on 2nd March 2004 on its 10 years journey towards a rendezvous with comet Churyumov-Gerasimenko ( Gardini et al., 1999). During its interplanetary flight towards its target Rosetta crosses the asteroid belt twice with the opportunity to observe at close quarters two asteroids: (2867)-Šteins in 2008 and (21)-Lutetia in 2010. The spacecraft design was such that these opportunities could be fully exploited to deliver valuable data to the scientific community. The mission trajectory was controlled such that Rosetta would fly next to asteroid Šteins on the 5th of September 2008 with a relative speed of 8.6 km/s at a minimum distance of 800 km. Mission operations have been carefully planned to achieve the best possible flyby scenario and scientific outcome. The flyby scenario, the optical navigation campaign, and the planning of the scientific observations had to be adapted by the Mission and the Science Operations Centres to the demanding requirements expressed by the scientific community. The flyby was conducted as planned with a large number of successful observations.

Deep Space 1 Using its Ion Engine Artist Concept

NASA Image and Video Library

2003-07-02

NASA's New Millennium Deep Space 1 spacecraft approaching the comet 19P/Borrelly. With its primary mission to serve as a technology demonstrator--testing ion propulsion and 11 other advanced technologies--successfully completed in September 1999, Deep Space 1 is now headed for a risky, exciting rendezvous with Comet Borrelly. NASA extended the mission, taking advantage of the ion propulsion and other systems to target the daring encounter with the comet in September 2001. Once a sci-fi dream, the ion propulsion engine has powered the spacecraft for over 12,000 hours. Another onboard experiment includes software that tracks celestial bodies so the spacecraft can make its own navigation decisions without the intervention of ground controllers. The first flight in NASA's New Millennium Program, Deep Space 1 was launched October 24, 1998 aboard a Boeing Delta 7326 rocket from Cape Canaveral Air Station, FL. Deep Space 1 successfully completed and exceeded its mission objectives in July 1999 and flew by a near-Earth asteroid, Braille (1992 KD), in September 1999. http://photojournal.jpl.nasa.gov/catalog/PIA04604

Rendezvous missions to temporarily captured near Earth asteroids

NASA Astrophysics Data System (ADS)

Brelsford, S.; Chyba, M.; Haberkorn, T.; Patterson, G.

2016-04-01

Missions to rendezvous with or capture an asteroid present significant interest both from a geophysical and safety point of view. They are key to the understanding of our solar system and are stepping stones for interplanetary human flight. In this paper, we focus on a rendezvous mission with 2006 RH120, an asteroid classified as a Temporarily Captured Orbiter (TCO). TCOs form a new population of near Earth objects presenting many advantages toward that goal. Prior to the mission, we consider the spacecraft hibernating on a Halo orbit around the Earth-Moon's L2 libration point. The objective is to design a transfer for the spacecraft from the parking orbit to rendezvous with 2006 RH120 while minimizing the fuel consumption. Our transfers use indirect methods, based on the Pontryagin Maximum Principle, combined with continuation techniques and a direct method to address the sensitivity of the initialization. We demonstrate that a rendezvous mission with 2006 RH120 can be accomplished with low delta-v. This exploratory work can be seen as a first step to identify good candidates for a rendezvous on a given TCO trajectory.

The Exploration of Near-Earth Objects

NASA Astrophysics Data System (ADS)

1998-01-01

Near-Earth objects (NEOs) are asteroids and comets with orbits that intersect or pass near that of our planet. About 400 NEOs are currently known, but the entire population contains perhaps 3000 objects with diameters larger than 1 km. These objects, thought to be similar in many ways to the ancient planetesimal swarms that accreted to form the planets, are interesting and highly accessible targets for scientific research. They carry records of the solar system's birth and the geologic evolution of small bodies in the interplanetary region. Because collisions of NEOs with Earth pose a finite hazard to life, the exploration of these objects is particularly urgent. Devising appropriate risk-avoidance strategies requires quantitative characterization of NEOS. They may also serve as resources for use by future human exploration missions. The scientific goals of a focused NEO exploration program are to determine their orbital distribution, physical characteristics, composition, and origin. Physical characteristics, such as size, shape, and spin properties, have been measured for approximately 80 NEOs using observations at infrared, radar, and visible wavelengths. Mineralogical compositions of a comparable number of NEOs have been inferred from visible and near-infrared spectroscopy. The formation and geologic histories of NEOs and related main-belt asteroids are currently inferred from studies of meteorites and from Galileo and Near-Earth Asteroid Rendezvous spacecraft flybys of three main-belt asteroids. Some progress has also been made in associating specific types of meteorites with main-belt asteroids, which probably are the parent bodies of most NEOs. The levels of discovery of NEOs in the future will certainly increase because of the application of new detection systems. The rate of discovery may increase by an order of magnitude, allowing the majority of Earth-crossing asteroids and comets with diameters greater than 1 km to he discovered in the next decade. A small fraction of NEOs are particularly accessible for exploration by spacecraft. To identify the exploration targets of highest scientific interest, the orbits and classification of a large number of NEOs should be determined by telescopic observations. Desired characterization would also include measurements of size, mass, shape, surface composition and heterogeneity, gas and dust emission, and rotation. Laboratory studies of meteorites can focus NEO exploration objectives and quantify the information obtained from telescopes. Once high-priority targets have been identified, various kinds of spacecraft missions (flyby, rendezvous, and sample return) can be designed. Some currently operational (Near-Earth Asteroid Rendezvous [NEAR]) or planned (Deep Space 1) U.S. missions are of the first two types, and other planned U.S. and Japanese spacecraft missions will return samples. Rendezvous missions with sample return are particularly desirable from a scientific perspective because of the very great differences in the analytical capabilities that can be brought to bear in orbit and in the laboratory setting. Although it would be difficult to justify human exploration of NEOs on the basis of cost-benefit analysis of scientific results alone, a strong case can be made for starting with NEOs if the decision to carry out human exploration beyond low Earth orbit is made for other reasons. Some NEOs are especially attractive targets for astronaut missions because of their orbital accessibility and short flight duration. Because they represent deep space exploration at an intermediate level of technical challenge, these missions would also serve as stepping stones for human missions to Mars. Human exploration of NEOs would provide significant advances in observational and sampling capabilities. With respect to ground based telescopic studies, the recommended baseline is that NASA and other appropriate agencies suupport research programs for interpreting the spectra of near-Earth objects (NEOs), continue and coordinate currently supported surveys to discover and determine the orbits of NEOs and develop policies for the public disclosure of results relating to potential hazards. Augmentation to this baseline program include in priority order: (1) provide routine or priority access to existiing ground-based optical and infrared telescopes and radar facilities for characterization of NEOs during favorable encounters; or (2) provide expanded, dedicated telescope access for characterization of NEOs. Appropriate augmentations to existing programs include the following: (1) Develop technological advances in spacecraft capabilities, including nonchemical propulsion and autonomous navigation systems, low-power and low-mass anlaytical instrumentation for remote and in situ studies, and multiple penetrators and other sampling and sample-handling systems to allow low-cost rendezvous and sample return missions; and (2) study technical requirements for human expeditions to NEOs. Although studies evaluating the risk of asteroid collisions with Earth and the means of averting them are desirable, they are beyond the scope of this report.

Physical properties of asteroids in comet-like orbits in the infrared asteroidal survey catalogs

NASA Astrophysics Data System (ADS)

Kim, Y.; Ishiguro, M.; Usui, F.

2014-07-01

Dormant comet and Infrared Asteroidal Survey Catalogs. Comet nucleus is a solid body consisting of dark refractory material and ice. Cometary volatiles sublimate from subsurface layer by solar heating, leaving behind large dust grains on the surface. Eventually, the appearance could turn into asteroidal rather than cometary. It is, therefore, expected that there would be ''dormant comets'' in the list of known asteroids. Over past decade, several ground-based studies have been performed to dig out such dormant comets. One common approach is applying a combination of optical and dynamical properties learned from active comet nucleus to the list of known asteroids. Typical comet nucleus has (i) Tisserand parameter with respect to Jupiter, T_{J}<3, (ii) low geometric albedo, p_{v}<0.1 and (iii) reddish or neutral spectra, similar to P, D, C-type asteroids. Following past ground-based surveys, infrared space missions gave us an opportunity to work on further study of dormant comets. To the present, three infrared asteroidal catalogs taken with IRAS[1], AKARI[2] and WISE[3] are available, providing information of sizes and albedos which are useful to study the physical properties of dormant comets as well as asteroids. Usui et al. (2014) merged three infrared asteroidal catalogs with valid sizes and albedos into single catalog, what they called I-A-W[4]. We applied a huge dataset of asteroids in I-A-W to investigate the physical properties of asteroids in comet-like orbits (ACOs, whose orbits satisfy Q>4.5 au and T_{J}<3). Here we present a study of ACOs in infrared asteroidal catalogs taken with AKARI, IRAS and WISE. In this presentation, we aim to introduce albedo and size properties of ACOs in infrared asteroidal survey catalogs, in combination with orbital and spectral properties from literature. Results and Implications. We summarize our finding and implication as followings: - are 123 ACOs (Q>4.5 au and T_J<3) in I-A-W catalog after rejection of objects with large orbital uncertainties. - Majority (˜80 %) of ACOs have low albedo (p_{v}<0.1), showing similar albedo distribution to active comet nuclei. - Low-albedo ACOs have the cumulative size distribution shallower than that of active comet nuclei. - High-albedo (p_{v}≥0.1) ACOs consist of small (D<3 km) bodies are concentrated in near-Earth space. - We suggest that such high-albedo, small near-Earth asteroids are susceptible to Yarkovsky effect and injected into comet-like orbits.

Mass study for modular approaches to a solar electric propulsion module

NASA Technical Reports Server (NTRS)

Sharp, G. R.; Cake, J. E.; Oglebay, J. C.; Shaker, F. J.

1977-01-01

The propulsion module comprises six to eight 30-cm thruster and power processing units, a mercury propellant storage and distribution system, a solar array ranging in power from 18 to 25 kW, and the thermal and structure systems required to support the thrust and power subsystems. Launch and on-orbit configurations are presented for both modular approaches. The propulsion module satisfies the thermal design requirements of a multimission set including: Mercury, Saturn, and Jupiter orbiters, a 1-AU solar observatory, and comet and asteroid rendezvous. A detailed mass breakdown and a mass equation relating the total mass to the number of thrusters and solar array power requirement is given for both approaches.

Space science: Causes and impacts of cutbacks to NASA's outer solar system exploration missions. Report to the Chairman, Subcommittee on Investigations and Oversight, Committee on Science, Space, and Technology, House of Representatives

NASA Astrophysics Data System (ADS)

Degnan, Frank

1993-12-01

The Comet Rendezvous Asteroid Flyby (CRAF)/Cassini program was first funded by the Congress in fiscal year 1990. Since then, it has encountered difficulties that resulted in the cancellation of CRAF, reduction of Cassini's original scientific capabilities, and extension of its launch date. At the request of the former Chairman of the Investigations and Oversight Subcommittee, House Committee on Science, Space, and Technology, GAO reviewed the program to identify the factors that led to the cancellation of the CRAF project and the prospects for continuation of the Cassini project.

Conceptual definition of a 50-100 kWe NEP system for planetary science missions

NASA Technical Reports Server (NTRS)

Friedlander, Alan

1993-01-01

The Phase 1 objective of this project is to assess the applicability of a common Nuclear Electric Propulsion (NEP) flight system of the 50-100 kWe power class to meet the advanced transportation requirements of a suite of planetary science (robotic) missions, accounting for differences in mission-specific payloads and delivery requirements. The candidate missions are as follows: (1) Comet Nucleus Sample Return; (2) Multiple Mainbelt Asteroid Rendezvous; (3) Jupiter Grand Tour (Galilean satellites and magnetosphere); (4) Uranus Orbiter/Probe (atmospheric entry and landers); (5) Neptune Orbiter/Probe (atmospheric entry and landers); and (6) Pluto-Charon Orbiter/Lander. The discussion is presented in vugraph form.

Noiseless coding for the magnetometer

NASA Technical Reports Server (NTRS)

Rice, Robert F.; Lee, Jun-Ji

1987-01-01

Future unmanned space missions will continue to seek a full understanding of magnetic fields throughout the solar system. Severely constrained data rates during certain portions of these missions could limit the possible science return. This publication investigates the application of universal noiseless coding techniques to more efficiently represent magnetometer data without any loss in data integrity. Performance results indicated that compression factors of 2:1 to 6:1 can be expected. Feasibility for general deep space application was demonstrated by implementing a microprocessor breadboard coder/decoder using the Intel 8086 processor. The Comet Rendezvous Asteroid Flyby mission will incorporate these techniques in a buffer feedback, rate-controlled configuration. The characteristics of this system are discussed.

Earth Science

NASA Image and Video Library

1996-01-31

The Near Earth Asteroid Rendezvous (NEAR) spacecraft embarks on a journey that will culminate in a close encounter with an asteroid. The launch of NEAR inaugurates NASA's irnovative Discovery program of small-scale planetary missions with rapid, lower-cost development cycles and focused science objectives. NEAR will rendezvous in 1999 with the asteroid 433 Eros to begin the first long-term, close-up look at an asteroid's surface composition and physical properties. NEAR's science payload includes an x-ray/gamma ray spectrometer, an near-infrared spectrograph, a laser rangefinder, a magnetometer, a radio science experiment and a multi-spectral imager.

Comet rendezvous mission design using Solar Electric Propulsion

NASA Technical Reports Server (NTRS)

Sackett, L. L.; Hastrup, R. C.; Yen, C.-W. L.; Wood, L. J.

1979-01-01

A dual comet (Halley Flyby/Tempel 2 Rendezvous) mission, which is planned to be the first to use the Solar Electric Propulsion System (SEPS), is to be launched in 1985. The purpose of this paper is to describe how the mission design attempts to maximize science return while working within spacecraft and other constraints. Science requirements and desires are outlined and specific instruments are considered. Emphasis is on the strategy for operations in the vicinity of Tempel 2, for which a representative profile is described. The mission is planned to extend about one year past initial rendezvous. Because of the large uncertainty in the comet environment the Tempel 2 operations strategy must be highly adaptive.

Cometary exploration in the shuttle era

NASA Technical Reports Server (NTRS)

Farquhar, R. W.; Wooden, W. H., II

1978-01-01

A comprehensive program plan for cometary exploration in the 1980-2000 time frame is proposed. Plans for ground-based observations, a Spacelab cometary observatory, and the Space Telescope are included in the observational program. The cometary mission sequence begins with a dual-spacecraft flyby of Halley's comet. The nominal mission strategy calls for a simultaneous launch of two spacecraft towards an intercept with Halley in March 1986. After the Halley encounter, the spacecraft are retargeted: one to intercept comet Borrelly in January 1988 and the other to intercept comet Tempel-2 in September 1988. The additional cometary intercepts are accomplished by utilizing a novel Earth-swingby technique. The next mission in the cometary program plan, a rendezvous with Encke's comet, is scheduled for launch in early 1990. It is planned to rendezvous with Encke in September 1992 at a heliocentric distance of 4 AU. Following this near-aphelion rendezvous, the spacecraft will remain with with Encke through the next two perihelion passages in February 1994 and May 1997. The rendezvous mission will be terminated about seven months after the second perihelion passage.

Application of a Laser Rangefinder for Space Object Imaging and Shape Reconstruction

DTIC Science & Technology

2014-02-10

the LRF can effectively create sufficiently dense point clouds for various asteroid and satellite shaped SOs, with low propellant consumption, by...bodies. An example is NASA’s Near Earth Asteroid Rendezvous (NEAR) mission, which employed an LRF to aid its rendezvous6 with asteroid 433 Eros in...laser beams. The ray-triangle intersection algorithm* deter- mines the point of intersection between the ray and a model of the scanned object. In order

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.

Chasing a Comet with a Solar Sail

NASA Technical Reports Server (NTRS)

Stough, Robert W.; Heaton, Andrew F.; Whorton, Mark S.

2008-01-01

Solar sail propulsion systems enable a wide range of missions that require constant thrust or high delta-V over long mission times. One particularly challenging mission type is a comet rendezvous mission. This paper presents optimal low-thrust trajectory designs for a range of sailcraft performance metrics and mission transit times that enables a comet rendezvous mission. These optimal trajectory results provide a trade space which can be parameterized in terms of mission duration and sailcraft performance parameters such that a design space for a small satellite comet chaser mission is identified. These results show that a feasible space exists for a small satellite to perform a comet chaser mission in a reasonable mission time.

Comet/Asteroid Protection System (CAPS): A Space-Based System Concept for Revolutionizing Earth Protection and Utilization of Near-Earth Objects

NASA Technical Reports Server (NTRS)

Mazanek, Daniel D.; Roithmayr, Carlos M.; Antol, Jeffrey; Kay-Bunnell, Linda; Werner, Martin R.; Park, Sang-Young; Kumar, Renjith R.

2002-01-01

There exists an infrequent, but significant hazard to life and property due to impacting asteroids and comets. There is currently no specific search for long-period comets, smaller near-Earth asteroids, or smaller short-period comets. These objects represent a threat with potentially little or no warning time using conventional ground-based telescopes. These planetary bodies also represent a significant resource for commercial exploitation, long-term sustained space exploration, and scientific research. The Comet/Asteroid Protection System (CAPS) would expand the current detection effort to include long-period comets, as well as small asteroids and short-period comets capable of regional destruction. A space-based detection system, despite being more costly and complex than Earth-based initiatives, is the most promising way of expanding the range of detectable objects, and surveying the entire celestial sky on a regular basis. CAPS is a future spacebased system concept that provides permanent, continuous asteroid and comet monitoring, and rapid, controlled modification of the orbital trajectories of selected bodies. CAPS would provide an orbit modification system capable of diverting kilometer class objects, and modifying the orbits of smaller asteroids for impact defense and resource utilization. This paper provides a summary of CAPS and discusses several key areas and technologies that are being investigated.

Perspectives on Comets, Comet-like Asteroids, and Their Predisposition to Provide an Environment That Is Friendly to Life

NASA Astrophysics Data System (ADS)

Bosiek, Katharina; Hausmann, Michael; Hildenbrand, Georg

2016-04-01

In recent years, studies have shown that there are many similarities between comets and asteroids. In some cases, it cannot even be determined to which of these groups an object belongs. This is especially true for objects found beyond the main asteroid belt. Because of the lack of comet fragments, more progress has been made concerning the chemical composition of asteroids. In particular, the SMASSII classification establishes a link between the reflecting spectra and chemical composition of asteroids and meteorites. To find clues for the chemical structure of comets, the parameters of all known asteroids of the SMASSII classification were compared to those of comet groups like the Encke-type comets, the Jupiter-family comets, and the Halley-type comets, as well as comet-like objects like the damocloids and the centaurs. Fifty-six SMASSII objects similar to comets were found and are categorized as comet-like asteroids in this work. Aside from the chemistry, it is assumed that the available energy on these celestial bodies plays an important role concerning habitability. For the determination of the available energy, the effective temperature was calculated. Additionally, the size of these objects was considered in order to evaluate the possibility of a liquid water core, which provides an environment that is more likely to support processes necessary to create the building blocks of life. Further study of such objects could be notable for the period of the Late Heavy Bombardment and could therefore provide important implications for our understanding of the inner workings of the prebiotic evolution within the Solar System since the beginning.

Perspectives on Comets, Comet-like Asteroids, and Their Predisposition to Provide an Environment That Is Friendly to Life.

PubMed

Bosiek, Katharina; Hausmann, Michael; Hildenbrand, Georg

2016-04-01

In recent years, studies have shown that there are many similarities between comets and asteroids. In some cases, it cannot even be determined to which of these groups an object belongs. This is especially true for objects found beyond the main asteroid belt. Because of the lack of comet fragments, more progress has been made concerning the chemical composition of asteroids. In particular, the SMASSII classification establishes a link between the reflecting spectra and chemical composition of asteroids and meteorites. To find clues for the chemical structure of comets, the parameters of all known asteroids of the SMASSII classification were compared to those of comet groups like the Encke-type comets, the Jupiter-family comets, and the Halley-type comets, as well as comet-like objects like the damocloids and the centaurs. Fifty-six SMASSII objects similar to comets were found and are categorized as comet-like asteroids in this work. Aside from the chemistry, it is assumed that the available energy on these celestial bodies plays an important role concerning habitability. For the determination of the available energy, the effective temperature was calculated. Additionally, the size of these objects was considered in order to evaluate the possibility of a liquid water core, which provides an environment that is more likely to support processes necessary to create the building blocks of life. Further study of such objects could be notable for the period of the Late Heavy Bombardment and could therefore provide important implications for our understanding of the inner workings of the prebiotic evolution within the Solar System since the beginning.

Rendezvous and Docking Strategy for Crewed Segment of the Asteroid Redirect Mission

NASA Technical Reports Server (NTRS)

Hinkel, Heather D.; Cryan, Scott P.; D'Souza, Christopher; Dannemiller, David P.; Brazzel, Jack P.; Condon, Gerald L.; Othon, William L.; Williams, Jacob

2014-01-01

This paper will describe the overall rendezvous, proximity operations and docking (RPOD) strategy in support of the Asteroid Redirect Crewed Mission (ARCM), as part of the Asteroid Redirect Mission (ARM). The focus of the paper is on the crewed mission phase of ARM, starting with the establishment of Orion in the Distant Retrograde Orbit (DRO) and ending with docking to the Asteroid Redirect Vechicle (ARV). The paper will detail the sequence of maneuvers required to execute the rendezvous and proximity operations mission phases along with the on-board navigation strategies, including the final approach phase. The trajectories to be considered will include target vehicles in a DRO. The paper will also discuss the sensor requirements for rendezvous and docking and the various trade studies associated with the final sensor selection. Building on the sensor requirements and trade studies, the paper will include a candidate sensor concept of operations, which will drive the selection of the sensor suite; concurrently, it will be driven by higher level requirements on the system, such as crew timeline constraints and vehicle consummables. This paper will address how many of the seemingly competing requirements will have to be addressed to create a complete system and system design. The objective is to determine a sensor suite and trajectories that enable Orion to successfully rendezvous and dock with a target vehicle in trans lunar space. Finally, the paper will report on the status of a NASA action to look for synergy within RPOD, across the crewed and robotic asteroid missions.

Performance comparison of earth and space storable bipropellant systems in interplanetary missions

NASA Technical Reports Server (NTRS)

Meissinger, H. F.

1978-01-01

The paper evaluates and compares the performance of earth-storable and space-storable liquid bipropellant propulsion systems in high-energy planetary mission applications, including specifically Saturn and Mercury orbiters, as well as asteroid and comet rendezvous missions. The discussion covers a brief review of the status of space-storable propulsion technology, along with an illustrative propulsion module design for a three-axis stabilized outer planet and cometary mission spacecraft of the Mariner class. The results take revised Shuttle/Upper Stage performance projections into account. It is shown that in some of the missions the performance improvement achievable in the ballistic transfer mode with space-storable spacecraft propulsion can provide a possible alternative to the use of solar-electric propulsion.

Comet/Asteroid Protection System (CAPS): Preliminary Space-Based Concept and Study Results

NASA Technical Reports Server (NTRS)

Mazanek, Daniel D.; Roithmayr, Carlos M.; Antol, Jeffrey; Park, Sang-Young; Koons, Robert H.; Bremer, James C.; Murphy, Douglas G.; Hoffman, James A.; Kumar, Renjith R.; Seywald, Hans

2005-01-01

There exists an infrequent, but significant hazard to life and property due to impacting asteroids and comets. There is currently no specific search for long-period comets, smaller near-Earth asteroids, or smaller short-period comets. These objects represent a threat with potentially little or no warning time using conventional ground-based telescopes. These planetary bodies also represent a significant resource for commercial exploitation, long-term sustained space exploration, and scientific research. The Comet/Asteroid Protection System (CAPS) is a future space-based system concept that provides permanent, continuous asteroid and comet monitoring, and rapid, controlled modification of the orbital trajectories of selected bodies. CAPS would expand the current detection effort to include long-period comets, as well as small asteroids and short-period comets capable of regional destruction. A space-based detection system, despite being more costly and complex than Earth-based initiatives, is the most promising way of expanding the range of detectable objects, and surveying the entire celestial sky on a regular basis. CAPS would provide an orbit modification system capable of diverting kilometer class objects, and modifying the orbits of smaller asteroids for impact defense and resource utilization. This Technical Memorandum provides a compilation of key related topics and analyses performed during the CAPS study, which was performed under the Revolutionary Aerospace Systems Concepts (RASC) program, and discusses technologies that could enable the implementation of this future system.

COMPASS Final Report: Near Earth Asteroids Rendezvous and Sample Earth Returns (NEARER)

NASA Technical Reports Server (NTRS)

Oleson, Steven R.; McGuire, Melissa L.

2009-01-01

In this study, the Collaborative Modeling for Parametric Assessment of Space Systems (COMPASS) team completed a design for a multi-asteroid (Nereus and 1996 FG3) sample return capable spacecraft for the NASA In-Space Propulsion Office. The objective of the study was to support technology development and assess the relative benefits of different electric propulsion systems on asteroid sample return design. The design uses a single, heritage Orion solar array (SA) (approx.6.5 kW at 1 AU) to power a single NASA Evolutionary Xenon Thruster ((NEXT) a spare NEXT is carried) to propel a lander to two near Earth asteroids. After landing and gathering science samples, the Solar Electric Propulsion (SEP) vehicle spirals back to Earth where it drops off the first sample s return capsule and performs an Earth flyby to assist the craft in rendezvousing with a second asteroid, which is then sampled. The second sample is returned in a similar fashion. The vehicle, dubbed Near Earth Asteroids Rendezvous and Sample Earth Returns (NEARER), easily fits in an Atlas 401 launcher and its cost estimates put the mission in the New Frontier s (NF's) class mission.

The asteroid rendezvous spacecraft. An adaptation study of TIROS/DMSP technology

NASA Technical Reports Server (NTRS)

1982-01-01

The feasibility of using the TIROS/DMSP Earth orbiting meteorological satellite in application to a near Earth asteroid rendezvous mission. System and subsystems analysis was carried out to develop a configuration of the spacecraft suitable for this mission. Mission analysis studies were also done and maneuver/rendezvous scenarios developed for baseline missions to both Anteros and Eros. The fact that the Asteroid mission is the most complex of the Pioneer class missions currently under consideration notwithstanding, the basic conclusion very strongly supports the suitability of the basic TIROS bus for this mission in all systems and subsystems areas, including science accommodation. Further, the modifications which are required due to the unique mission are very low risk and can be accomplished readily. The key issue is that in virtually every key subsystem, the demands of the Asteroid mission are a subset of the basic meteorological satellite mission. This allows a relatively simple reconfiguration to be accomplished without a major system redesign.

Lunar and Planetary Science XXXV: Asteroids, Meteors, Comets

NASA Technical Reports Server (NTRS)

2004-01-01

The session Asteroids, Meteors, Comets includes the following topics: 1) Where Some Asteroid Parent Bodies; 2) The Collisional Evolution of the Main Belt Population; 3) On Origin of Ecliptic Families of Periodic Comets; 4) Mineralogy and Petrology of Laser Irradiated Carbonaceous Chondrite Mighei; and 5) Interaction of the Gould Belt and the Earth.

Physical Characteristics of Asteroid-like Comet Nucleus C/2001 OG108 (LONEOS)

NASA Technical Reports Server (NTRS)

Abell, P. A.; Fernandez, Y. R.; Pravec, P.; French, L. M.; Farnham, T. L.; Gaffey, M. J.; Hardersen, P. S.; Kusnirak, P.; Sarounova, L.; Sheppard, S. S.

2003-01-01

For many years several investigators have suggested that some portion of the near-Earth asteroid population may actually be extinct cometary nuclei. Evidence used to support these hypotheses was based on: observations of asteroid orbits and associated meteor showers (e.g. 3200 Phaethon and the Geminid meteor shower); low activity of short period comet nuclei, which implied nonvolatile surface crusts (e.g. Neujmin 1, Arend-Rigaux); and detections of transient cometary activity in some near-Earth asteroids (e.g. 4015 Wilson-Harrington). Recent investigations have suggested that approximately 5-10% of the near- Earth asteroid population may be extinct comets. However if members of the near-Earth asteroid population are extinct cometary nuclei, then there should be some objects within this population that are near their final stages of evolution and so should demonstrate only low levels of activity. The recent detections of coma from near-Earth object 2001 OG108 have renewed interest in this possible comet-asteroid connection. This paper presents the first high quality ground-based near-infrared reflectance spectrum of a comet nucleus combined with detailed lightcurve and albedo measurements.

Photon momentum transfer plane for asteroid, meteoroid, and comet orbit shaping

NASA Technical Reports Server (NTRS)

Campbell, Jonathan W. (Inventor)

2004-01-01

A spacecraft docks with a spinning and/or rotating asteroid, meteoroid, comet, or other space object, utilizing a tether shaped in a loop and utilizing subvehicles appropriately to control loop instabilities. The loop is positioned about a portion of the asteroid and retracted thereby docking the spacecraft to the asteroid, meteoroid, comet, or other space object. A deployable rigidized, photon momentum transfer plane of sufficient thickness may then be inflated and filled with foam. This plane has a reflective surface that assists in generating a larger momentum from impinging photons. This plane may also be moved relative to the spacecraft to alter the forces acting on it, and thus on the asteroid, meteoroid, comet, or other space object to which it is attached. In general, these forces may be utilized, over time, to alter the orbits of asteroids, meteoroids, comets, or other space objects. Sensors and communication equipment may be utilized to allow remote operation of the rigidized, photon momentum transfer plane and tether.

Rosetta Planetary Science Archive (PSA) Status

NASA Astrophysics Data System (ADS)

Wirth, Kristin R.; Cardesin, A.; Barthelemy, M.; Diaz del Rio, J.; Zender, J.; Arviset, C.

2006-09-01

The Planetary Science Archive (PSA) is an online database (accessible via http://www.rssd.esa.int/PSA) implemented by ESA/RSSD. Currently the PSA contains the science data from the Giotto (Halley), Mars Express and SMART-1 (Moon) missions, and the Rosetta Supplementary Archive (Wirtanen). The PSA user is offered a broad range of search possibilities. Search queries can be combined without restrictions and are executed across the whole database. The PSA utilizes the Planetary Data System (PDS) standard. In spring 2007 the PSA will provide the first science and engineering data collected by Rosetta. In preparation for the initial Peer Review to be performed before publication of these data, an Internal Review was held in March 2006, executed by staff internal to the organizations responsible for the Rosetta archiving (ESA, PDS, CNES). The Internal Reviewers identified shortcomings in documentation, data structures, and completeness of the data delivery. They recommended the usage of unified conventions and formats across different instruments. Work is ongoing to include standardized geometry information in the datasets. Rosetta was launched in March 2004 to rendezvous with comet 67P/Churyumov-Gerasimenko (C-G) in May 2014. After having placed a lander on the comet's surface, the Rosetta orbiter will continue to orbit C-G and accompany the comet through perihelion. Rosetta makes use of three Earth swingbys and one Mars swingby in order to reach C-G. Rosetta will also perform close flybys at two asteroids, namely 2867 Steins in September 2008 and 21 Lutetia in July 2010. In addition, Rosetta makes scientific observations of targets of opportunity, e.g. lightcurves of the flyby asteroids to study the rotation, and plasma measurements when passing through cometary ion tails or meteoroid streams. Rosetta continuously monitored the encounter of the Deep Impact probe with comet 9P/Tempel 1 over an extended period of 16 days around the impact on 4 July 2005.

The Search for Life in the Solar System

NASA Astrophysics Data System (ADS)

Ehrenfreund, Pascale

2016-07-01

To unravel the origins of life on Earth and possibly elsewhere remains one of mankind's most important discoveries. Basic building blocks of life are widespread in planetary systems in our Milky Way and other galaxies. Extraterrestrial material delivered to young terrestrial planetary surfaces in the early history of our solar system through asteroids, comets and meteorites may have provided significant raw material for the emergence of life on Earth. Since August 2014 the comet rendezvous mission Rosetta has monitored the evolution of comet 67P/Churyumov-Gerasimenko during its approach to the Sun and observed numerous volatiles and complex organic compounds on the comet surface. Several asteroid sample return missions as well as the improved analyses of key meteorites increase our knowledge about the organic inventory that seeded the young planets. Prokaryotic, anaerobic bacteria, which are approximately 3.5 billion years old, represent the first evidence for life on Earth. Since then, life has evolved to high complexity and adapted to nearly every explored environment on our planet. Extreme life on Earth has expanded the list of potentially habitable solar system environments. However, our neighbor planet Mars is the most promising target to search for life within our solar system. Data from the Curiosity rover show regions that were habitable in the past, traces of organic carbon and active CH_4 in the Martian atmosphere at present. Recent discoveries such as the plumes from the southern polar region of Enceladus and plume activity on Europa strengthen the long-standing hypothesis that moons in our solar system contain substantial bodies of water and are probably habitable. Since decades, a fleet of robotic space missions target planets, moons and small bodies to reveal clues on the origin of our solar system and life beyond Earth. This lecture will review and discuss past, current and future space missions investigating habitability and biosignatures in our solar system and the science and technology preparation for robotic and human exploration efforts.

Major achievements of the Rosetta mission in connection with the origin of the solar system

NASA Astrophysics Data System (ADS)

Barucci, M. A.; Fulchignoni, M.

2017-10-01

Comets have been studied from a long time and are believed to preserve pristine materials, so they are fundamental to understand the origin of the solar system and life. Starting in the early 1990s, ESA decided to have a more risky and fantastic mission to a comet. As Planetary Cornerstone mission of the ESA Horizon 2000 program, the Rosetta mission was selected with the aim of realizing two asteroid fly-bys, a rendezvous with a comet to deliver a surface science package and to hover around the comet from 4 AU inbound up to perihelion and outbound back to 3.7 AU. The mission was successfully launched on March 2, 2004 with Ariane V that started its 10-year journey toward comet 67P/Churyumov-Gerasimenko. After several planetary gravity assists, Rosetta flew by two asteroids—on September 5, 2008 (Steins) and on July 10, 2010 (Lutetia), respectively, and performed the comet orbit insertion maneuver on August 6, 2014. The onboard instruments characterized the nucleus orbiting the comet at altitudes down to few kilometers. On November 12, 2014, the lander Philae was delivered realizing the first landing ever on a comet surface. Although the exploration of the comet was planned up to the end of 2015, the mission duration was extended for nine more months than the nominal one, to follow the comet on its outbound orbit. To terminate the mission, following a series of very low orbits, a controlled impact of Rosetta spacecraft with the comet was realized on September 30, 2016. The scientific objectives of the mission have been largely achieved. The challenging mission provided the science community with an enormous quantity of data of extraordinary scientific value. In this paper, a detailed description of the mission and the highlights of the obtained scientific results on the exploration of an extraordinary world are presented. The paper also includes lessons learned and directions for the future.

Asteroid (457175) 2008 GO98: a quasi-Hilda comet. (Italian Title: Asteroide (457175) 2008 GO98:una cometa "quasi-Hilda")

NASA Astrophysics Data System (ADS)

Bacci, P.

2017-12-01

Cometary activity in the asteroid (457175) 2008 GO98 was observed at San Marcello Observatory, highlighting an extended coma and a tail of 36 arcseconds. The asteroid should be classified as a quasi-Hilda comet.

Asteroid Redirect Crewed Mission Nominal Design and Performance

NASA Technical Reports Server (NTRS)

Condon, Gerald; williams, Jacob

2014-01-01

In 2010, the President announced that, in 2025, the U.S. intended to launch a human mission to an asteroid [1]. This announcement was followed by the idea of a Capability Driven Framework (CDF) [2], which is based on the idea of evolving capabilities from less demanding to more demanding missions to multiple possible destinations and with increased flexibility, cost effectiveness and sustainability. Focused missions, such as a NASA inter-Center study that examined the viability and implications of sending a crew to a Near Earth Asteroid (NEA) [3], provided a way to better understand and evaluate the utility of these CDF capabilities when applied to an actual mission. The long duration of the NEA missions were contrasted with a concept described in a study prepared for the Keck Institute of Space Studies (KISS) [4] where a robotic spacecraft would redirect an asteroid to the Earth-Moon vicinity, where a relatively short duration crewed mission could be conducted to the captured asteroid. This mission concept was included in the National Aeronautics and Space Administration (NASA) fiscal year 2014 budget request, as submitted by the NASA Administrator [5]. NASA studies continued to examine the idea of a crewed mission to a captured asteroid in the Earth-Moon vicinity. During this time was an announcement of NASA's Asteroid Grand Challenge [6]. Key goals for the Asteroid Grand Challenge are to locate, redirect, and explore an asteroid, as well as find and plan for asteroid threats. An Asteroid Redirect Mission (ARM) study was being conducted, which supports this Grand Challenge by providing understanding in how to execute an asteroid rendezvous, capture it, and redirect it to Earth-Moon space, and, in particular, to a distant retrograde orbit (DRO). Subsequent to the returning of the asteroid to a DRO, would be the launch of a crewed mission to rendezvous with the redirected asteroid. This report examines that crewed mission by assessing the Asteroid Redirect Crewed Mission (ARCM) nominal design and performance costs associated with an Orion based crewed rendezvous mission to a captured asteroid in an Earth-Moon DRO. The ARM study includes two fundamental mission phases: 1) The Asteroid Redirect Robotic Mission (ARRM) and 2) the ARCM. The ARRM includes a solar electric propulsion based robotic asteroid return vehicle (ARV) sent to rendezvous with a selected near Earth asteroid, capture it, and return it to a DRO in the Earth-Moon vicinity. The DRO is selected over other possible asteroid parking orbits due to its achievability (by both the robotic and crewed vehicles) and by its stability (e.g., no orbit maintenance is required). After the return of the asteroid to the Earth-Moon vicinity, the ARCM is executed and carries a crew of two astronauts to a DRO to rendezvous with the awaiting ARV with the asteroid. The outbound and inbound transfers employ lunar gravity assist (LGA) flybys to reduce the Orion propellant requirement for the overall nominal mission, which provides a nominal mission with some reserve propellant for possible abort situations. The nominal mission described in this report provides a better understanding of the mission considerations as well as the feasibility of such a crewed mission, particularly with regard to spacecraft currently undergoing development, such as the Orion vehicle and the Space Launch System (SLS).

Trajectory design for a rendezvous mission to Earth's Trojan asteroid 2010 TK7

NASA Astrophysics Data System (ADS)

Lei, Hanlun; Xu, Bo; Zhang, Lei

2017-12-01

In this paper a rendezvous mission to the Earth's Trojan asteroid 2010 TK7 is proposed, and preliminary transfer trajectories are designed. Due to the high inclination (∼ 20.9°) of the target asteroid relative to the ecliptic plane, direct transfers usually require large amounts of fuel consumption, which is beyond the capacity of current technology. As gravity assist technique could effectively change the inclination of spacecraft's trajectory, it is adopted to reduce the launch energy and rendezvous velocity maneuver. In practical computation, impulsive and low-thrust, gravity-assisted trajectories are considered. Among all the trajectories computed, the low-thrust gravity-assisted trajectory with Venus-Earth-Venus (V-E-V) swingby sequence performs the best in terms of propellant mass. For a spacecraft with initial mass of 800 kg , propellant mass of the best trajectory is 36.74 kg . Numerical results indicate that both the impulsive and low-thrust, gravity-assisted trajectories corresponding to V-E-V sequence could satisfy mission constraints, and can be applied to practical rendezvous mission.

Radar observations of asteroids and comets

NASA Technical Reports Server (NTRS)

Ostro, S. J.

1985-01-01

Radar techniques for the observation of asteroids and comets are reviewed, emphasizing the logical basis for inferring physical properties from radar measurements. Results to date are reviewed, focusing on some recent highlights of the research to demonstrate the synergism between radar and other ground-based techniques. Particular attention is given to the asteroids 2 Pallas, 16 Psyche, 2101 Adonis, and the comet IRAS-Araki-Alcock.

An electromagnetic/electrostatic dual cathode system for electron beam instruments

NASA Technical Reports Server (NTRS)

Bradley, J. G.; Conley, J. M.; Wittry, D. B.; Albee, A. L.

1986-01-01

A method of providing cathode redundancy which consists of two fixed cathodes and uses electromagnetic and/or electrostatic fields to direct the electron beam to the electron optical axis is presented, with application to the cathode system of the Scanning Electron Microscope and Particle Analyzer proposed for NASA's Mariner Mark II Comet Rendezvous/Asteroid Flyby projected for the 1990s. The symmetric double deflection system chosen has the optical property that the image of the effective electron source is formed above the magnet assembly near the apparent position of the effective source, and it makes the transverse positions of the electron sources independent of the electron beam energy. Good performance of the system is found, with the sample imaging resolution being the same as for the single-axis cathode.

Tough budget year ahead, says NASA's Fisk

NASA Astrophysics Data System (ADS)

Cole, Stephen

1992-02-01

Lennard Fisk, head of NASA's space science and applications division, painted a bleak picture for space scientists on February 14 as the Bush administration's fiscal 1993 budget headed to Congress. Speaking at the annual meeting of the Space Science Working Group in Washington, D.C., Fisk said “It's going to take a miracle to get the $2,985 billion request” for space science in this year's NASA budget.Fisk held out no hope that programs already cut from the budget, such as the Comet Rendezvous/Asteroid Flyby mission, would be reinstated. The CRAF cancellation was “a $50 million issue in fiscal 1993,” said Fisk, “and it was $50 million that simply wasn't there.” His office “was under enormous pressure to take something off the plate,” he said.

Study of a comet rendezvous mission, volume 1

NASA Technical Reports Server (NTRS)

1972-01-01

The feasibility, scientific objectives, modes of exploration and implementation alternatives of a rendezvous mission to Encke's comet in 1984 are considered. Principal emphasis is placed on developing the scientific rationale for such a mission, based on available knowledge and best estimates of this comet's physical characteristics, including current theories of its origin, evolution and composition. Studied are mission profile alternatives, performance tradeoffs, preferred exploration strategy, and a spacecraft design concept capable of performing this mission. The study showed that the major scientific objectives can be met by a Titan IIID/Centaur-launched 17.5 kw solar electric propulsion spacecraft which carries 60 kg of scientific instruments and is capable of extensive maneuvering within the comet envelope to explore the coma, tail and nucleus.

CCD scanning for asteroids and comets

NASA Technical Reports Server (NTRS)

Gehrels, T.; Mcmillan, R. S.

1986-01-01

A change coupled device (CCD) is used in a scanning mode to find new asteroids and recover known asteroids and comet nuclei. Current scientific programs include recovery of asteroids and comet nuclei requested by the Minor Planet Center (MPC), discovery of new asteroids in the main belt and of unusual orbital types, and follow-up astrometry of selected new asteroids discovered. The routine six sigma limiting visual magnitude is 19.6 and slightly more than a square degree is scanned three times every 90 minutes of observing time during the fortnight centered on New Moon. Semiautomatic software for detection of moving objects is in routine use; angular speeds as low as 11.0 arcseconds per hour were distinguished from the effects of the Earth's atmosphere on the field of view. A typical set of three 29-minute scans near the opposition point along the ecliptic typically nets at least 5 new main-belt asteroids down to magnitude 19.6. In 18 observing runs (months) 43 asteroids were recovered, astrometric and photometric data on 59 new asteroids were reported, 10 new asteroids with orbital elements were consolidated, and photometry and positions of 22 comets were reported.

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

NASA Technical Reports Server (NTRS)

Bowell, Edward

1988-01-01

The work comprises observational, theoretical, and computational research on asteroids, together with a smaller effort concerning the astrometry of comets and Jupiter's satellites JVI through JXIII. 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. About 2000 accurate photographic positions of asteroids and comets, including a number from the Lowell, Palomar, and Goethe-Link archival plate collections, the last of which was donated to us last winter by Indiana University were measured and published. Charge coupled device (CCD) astrometry of 36 faint targets was undertaken, including 4 comets; JVI, JVII, JVIII, JLX, JXI, and JXII; and 26 asteroids, most of which are Earth-approachers. A deep, bias-correctable asteroid survey (LUKAS), the aim of which is to determine the true spatial distribution of asteroids down to subkilometer diameters was started. A series of eight plates at the UK Schmidt telescope that contain images of asteroids as faint as V approximately 22 mag was obtained. Analysis of microdensitometric scans of two plates has shown that about 98 percent of the asteroid images could be identified completely automatically.

Solar Sail Application to Comet Nucleus Sample Return

NASA Technical Reports Server (NTRS)

Taylor, Travis S.; Moton, Tryshanda T.; Robinson, Don; Anding, R. Charles; Matloff, Gregory L.; Garbe, Gregory; Montgomery, Edward

2003-01-01

Many comets have perihelions at distances within 1.0 Astronomical Unit (AU) from the sun. These comets typically are inclined out of the ecliptic. We propose that a solar sail spacecraft could be used to increase the inclination of the orbit to match that of these 1.0 AU comets. The solar sail spacecraft would match the orbit velocity for a short period of time, which would be long enough for a container to be injected into the comet's nucleus. The container would be extended from a long durable tether so that the solar sail would not be required to enter into the potentially degrading environment of the comet s atmosphere. Once the container has been filled with sample material, the tether is retracted. The solar sail would then lower its inclination and fly back to Earth for the sample return. In this paper, we describe the selection of cometary targets, the mission design, and the solar sailcraft design suitable for sail-comet rendezvous as well as possible rendezvous scenarios.

Integrated Modeling of Spacecraft Touch-and-Go Sampling

NASA Technical Reports Server (NTRS)

Quadrelli, Marco

2009-01-01

An integrated modeling tool has been developed to include multi-body dynamics, orbital dynamics, and touch-and-go dynamics for spacecraft covering three types of end-effectors: a sticky pad, a brush-wheel sampler, and a pellet gun. Several multi-body models of a free-flying spacecraft with a multi-link manipulator driving these end-effectors have been tested with typical contact conditions arising when the manipulator arm is to sample the surface of an asteroidal body. The test data have been infused directly into the dynamics formulation including such information as the mass collected as a function of end-effector longitudinal speed for the brush-wheel and sticky-pad samplers, and the mass collected as a function of projectile speed for the pellet gun sampler. These data represent the realistic behavior of the end effector while in contact with a surface, and represent a low-order model of more complex contact conditions that otherwise would have to be simulated. Numerical results demonstrate the adequacy of these multibody models for spacecraft and manipulator- arm control design. The work contributes to the development of a touch-and-go testbed for small body exploration, denoted as the GREX Testbed (GN&C for Rendezvous-based EXploration). The GREX testbed addresses the key issues involved in landing on an asteroidal body or comet; namely, a complex, low-gravity field; partially known terrain properties; possible comet outgassing; dust ejection; and navigating to a safe and scientifically desirable zone.

A binary main-belt comet.

PubMed

Agarwal, Jessica; Jewitt, David; Mutchler, Max; Weaver, Harold; Larson, Stephen

2017-09-20

Asteroids are primitive Solar System bodies that evolve both collisionally and through disruptions arising from rapid rotation. These processes can lead to the formation of binary asteroids and to the release of dust, both directly and, in some cases, through uncovering frozen volatiles. In a subset of the asteroids called main-belt comets, the sublimation of excavated volatiles causes transient comet-like activity. Torques exerted by sublimation measurably influence the spin rates of active comets and might lead to the splitting of bilobate comet nuclei. The kilometre-sized main-belt asteroid 288P (300163) showed activity for several months around its perihelion 2011 (ref. 11), suspected to be sustained by the sublimation of water ice and supported by rapid rotation, while at least one component rotates slowly with a period of 16 hours (ref. 14). The object 288P is part of a young family of at least 11 asteroids that formed from a precursor about 10 kilometres in diameter during a shattering collision 7.5 million years ago. Here we report that 288P is a binary main-belt comet. It is different from the known asteroid binaries in its combination of wide separation, near-equal component size, high eccentricity and comet-like activity. The observations also provide strong support for sublimation as the driver of activity in 288P and show that sublimation torques may play an important part in binary orbit evolution.

Asteroid and comet flux in the neighborhood of the earth

NASA Technical Reports Server (NTRS)

Shoemaker, Eugene M.; Shoemaker, Carolyn S.; Wolfe, Ruth F.

1988-01-01

Significant advances in the knowledge and understanding of the flux of large solid objects in the neighborhood of Earth have occurred. The best estimates of the collision rates with Earth of asteroids and comets and the corresponding production of impact craters are presented. Approximately 80 Earth-crossing asteroids were discovered through May 1988. Among 42 new Earth-crossing asteroids found in the last decade, two-thirds were discovered from observations at Palomar Observatory and 15 were discovered or independently detected in dedicated surveys with the Palomar Observatory and 15 were discovered or independently detected in dedicated surveys with the Palomar 46 cm Schmidt. Probabilities of collision with Earth have been calculated for about two-thirds of the known Earth-crossing asteroids. When multiplied by the estimated population of Earth-crossers, this yields an estimated present rate of collision about 65 pct higher than that previously reported. Spectrophotometric data obtained chiefly in the last decade show that the large majority of obvserved Earth-crossers are similar to asteroids found in the inner part of the main belt. The number of discovered Earth-crossing comets is more than 4 times greater than the number of known Earth-crossing asteroids, but reliable data on the sizes of comet nuclei are sparse. The flux of comets almost certainly was highly variable over late geologic time, owing to the random perturbation of the Oort comet cloud by stars in the solar neighborhood.

Dormant Comets in the Near-Earth Asteroid Population

NASA Astrophysics Data System (ADS)

Mommert, Michael; Harris, Alan W.; Mueller, Michael; Hora, Joseph L.; Trilling, David E.; Knight, Matthew; Bottke, William F.; Thomas, Cristina; Delbo', Marco; Emery, Josh P.; Fazio, Giovanni; Smith, Howard A.

2015-11-01

The population of near-Earth objects comprises active comets and asteroids, covering a wide range of dynamical parameters and physical properties. Dormant (or extinct) comets, masquerading as asteroids, have long been suspected of supplementing the near-Earth asteroid (NEA) population. We present a search for asteroidal objects of cometary origin based on dynamical and physical considerations. Our study is based on albedos derived within the ExploreNEOs program and is extended by adding data from NEOWISE and the Akari asteroid catalog. We use a statistical approach to identify asteroids on orbits that resemble those of short-period near-Earth comets using the Tisserand parameter with respect to Jupiter, the aphelion distance, and the minimum orbital intersection distance with respect to Jupiter. We identify a total of 23 near-Earth asteroids from our sample that are likely to be dormant short-period near-Earth comets and, based on a de-biasing procedure applied to the cryogenic NEOWISE survey, estimate both magnitude-limited and size-limited fractions of the NEA population that are dormant short-period comets. We find that 0.3-3.3% of the NEA population with H <= 21, and 9(+2/-5)% of the population with diameters d >= 1 km, are dormant short-period near-Earth comets. We also present an observation program that utilizes the 1.8m Vatican Advanced Technology Telescope (VATT) on Mt. Graham, AZ, to identify dormant comet candidates and search for activity in these objects. Our targets are NEAs on comet-like orbits, based on the dynamical criteria derived in the above study, that are accessible with the VATT (V <= 22). We identify dormant comets based on their optical spectral slope, represented by V-R color measurements, as albedo measurements for most of these objects are not available. For each target we measure and monitor its V magnitude in order to reveal activity outbreaks. We also search for extended emission around our targets using deep imaging and a point-spread-function subtraction technique that allows us to obtain an upper limit on the dust production rate in each target. We present preliminary results from this program. This work is supported in part by funding from the Spitzer Science Center.

Comet composition and density analyzer

NASA Technical Reports Server (NTRS)

Clark, B. C.

1982-01-01

Distinctions between cometary material and other extraterrestrial materials (meteorite suites and stratospherically-captured cosmic dust) are addressed. The technique of X-ray fluorescence (XRF) for analysis of elemental composition is involved. Concomitant with these investigations, the problem of collecting representative samples of comet dust (for rendezvous missions) was solved, and several related techniques such as mineralogic analysis (X-ray diffraction), direct analysis of the nucleus without docking (electron macroprobe), dust flux rate measurement, and test sample preparation were evaluated. An explicit experiment concept based upon X-ray fluorescence analysis of biased and unbiased sample collections was scoped and proposed for a future rendezvous mission with a short-period comet.

Comet nuclei and Trojan asteroids - A new link and a possible mechanism for comet splittings

NASA Technical Reports Server (NTRS)

Hartmann, William K.; Tholen, David J.

1990-01-01

Relatively elongated shapes, implied by recent evidence of a greater incidence of high amplitude lightcurves for comet nuclei and Trojan asteroids than for similarly scaled main belt asteroids, are suggested to have evolved among comet nuclei and Trojans due to volatile loss. It is further suggested that such an evolutionary course may account for observed comet splitting; rotational splitting may specifically occur as a result of evolution in the direction of an elongated shape through sublimation. Supporting these hypotheses, the few m/sec separation velocities projected for rotationally splitting elongated nuclei are precisely in the observed range.

Rogue Asteroids and Doomsday Comets: The Search for the Million Megaton Menace That Threatens Life on Earth

NASA Astrophysics Data System (ADS)

Steel, Duncan

1997-09-01

Could a giant asteroid or comet crash into Earth and destroy life as we know it? Many astronomers who once discredited the risks are now convinced. You will be too after reading Duncan Steel's critically acclaimed examination of the evidence of Earth's encounters with killer comets and asteroids. Acclaim for Rogue Asteroids and Doomsday Comets "A chilling and utterly convincing account of a cosmic menace that must not be ignored any longer. This book is a welcome challenge to the scientific prejudice against catastrophism." --Paul Davies, author of The Mind of God "Written in clear prose for the layperson, this gripping report advocates the creation of an international search program to detect, intercept, and divert Earth-menacing asteroids and comets." --Publishers Weekly. "Steel writes clearly and ominously, and he should be listened to." --The Daily Telegraph (London) A selection of the Astronomy Book Club A Library Journal "Best Science Book of the Year" selection

Are Adonis and Hephaistos "Extinct" Comets?

NASA Astrophysics Data System (ADS)

Babadzhanov, P. B.

The investigation of the evolution of Earth-approaching asteroids with the aim of revealing their meteor streams is one of the ways to determine if these asteroids are extinct comets. The orbital evolution of asteroids 2101 Adonis and 2212 Hephaistos studied, respectively, by AlfanGoryachev and Everhart methods shows that these asteroids cross the Earth's orbit four times. Their possible meteoroid swarms may therefore produce four meteor showers each. In this work, the theoretically predicted orbital elements and radiants of these streams are compared to the available observational data. In the cases of both Adonis and Hephaistos, all four meteor showers are shown to be active. Most likely, these asteroids are extinct comets.

The bare nucleus of comet Neujmin 1

NASA Technical Reports Server (NTRS)

Campins, Humberto; A'Hearn, Michael F.; Mcfadden, Lucy-Ann

1987-01-01

Simultaneous visible and infrared observations of comet P/Neujmin 1 1984c are presented which show that the comet has a large (mean radius 10 km), dark (geometric albedo 2-3 percent) nucleus with a surface which is mostly inert material but which still shows a low level of gaseous activity. This is the first physical evidence that cometary nuclei can leave behind an inert body after the coma activity ceases. No asteroid or asteroid class has been found to match the reflectance and albedo of this comet except possibly some D asteroids.

The gas production rate of periodic comet d'Arrest

NASA Technical Reports Server (NTRS)

Festou, Michel C.; Feldman, Paul D.; Ahearn, Michael F.

1992-01-01

Comet P/d'Arrest is a potential target for a rendezvous mission to a short period comet. Its light curve is rather peculiar, the comet being active only after perihelion passage. One apparition out of two is easy to observe from the ground. The 1995 apparition of the comet will offer a unique opportunity to characterize the outgassing properties of its nucleus.

Accessibility of near-Earth asteroids, 1990

NASA Technical Reports Server (NTRS)

Hulkower, Neal D.; Child, Jack B.

1991-01-01

Previous research which analyzed the accessibility of all known near-Earth asteroids is updated. Since then, many new near-Earth asteroids have been discovered, and 1928 DB, the most accessible asteroid at that time, has been recovered. Many of these recently discovered near-Earth asteroids have promising orbital characteristics. In addition to accessibility (as defined by minimum global delta v), ideal rendezvous opportunities are identified.

Direct Characterization of Comets and Asteroids via Cosmic Dust Analysis from the Deep Space Gateway

NASA Technical Reports Server (NTRS)

Fries, M.; Fisher, K.

2018-01-01

The Deep Space Gateway (DSG) may provide a platform for direct sampling of a large number of comets and asteroids, through employment of an instrument for characterizing dust from these bodies. Every year, the Earth traverses through debris streams of dust and small particles from comets and asteroids in Earth-crossing orbits, generating short-lived outbursts of meteor activity commonly known as "meteor showers" (Figure 1). The material in each debris stream originates from a distinct parent body, many of which have been identified. By sampling this material, it is possible to quantitatively analyze the composition of a dozen or more comets and asteroids (See Figure 2, following page) without leaving cislunar space.

Cometary Coma Chemical Composition (C4) Mission

NASA Technical Reports Server (NTRS)

Carle, Glenn C.; Clark, Benton C.; Knocke, Philip C.; OHara, Bonnie J.; Adams, Larry; Niemann, Hasso B.; Alexander, Merle; Veverka, Joseph; Goldstein, Raymond; Huebner, Walter;

Abstracts for the International Conference on Asteroids, Comets, Meteors 1991

NASA Technical Reports Server (NTRS)

1991-01-01

Topics addressed include: chemical abundances; asteroidal belt evolution; sources of meteors and meteorites; cometary spectroscopy; gas diffusion; mathematical models; cometary nuclei; cratering records; imaging techniques; cometary composition; asteroid classification; radio telescopes and spectroscopy; magnetic fields; cosmogony; IUE observations; orbital distribution of asteroids, comets, and meteors; solar wind effects; computerized simulation; infrared remote sensing; optical properties; and orbital evolution.

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.

Organic material: Asteroids, meteorites, and planetary satellites

NASA Technical Reports Server (NTRS)

Cruikshank, Dale P.; Kerridge, John F.

1992-01-01

Telescopic observations in in situ spacecraft investigations over the last two decades have shown that many planetary satellites, asteroids, and comets have surfaces containing very dark material that is either neutral (black) or red in color. Although comets are not the focus of this paper, the possible relationship of comets to asteroids, meteorites, and interplanetary dust is briefly discussed in the context of their dark-matter component. The following topics are discussed with respect to their organic content: carbonaceous chondrites; asteroids; low-albedo planetary satellites; and Pluto, Charon, and Triton. Laboratory studies and a summary are also presented.

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?

Time travel and chemical evolution - A look at the outer solar system

NASA Astrophysics Data System (ADS)

Owen, T.

1987-12-01

It has been hypothesized that the chemical conditions today on the planets and moons of the outer solar system are similar to conditions on earth soon after it formed. If this is so, much can be learned about the chemistry that led to life on earth. While Jupiter is a poor terrestrial analog, its satellite Europa has a smooth icy surface that may cover a layer of liquid water tens of kilometers deep. It is possible that sunlight could filter through cracks in the ice, providing energy to drive chemical reactions in the water below the ice. It is noted that the surface of Titan may include lakes or oceans of ethane and that Triton may also have liquids on its surface. Studies of cometary nuclei will be undertaken during the Comet Rendezvous-Asteroid Flyby mission.

Cost, capability, and risk for planetary operations

NASA Technical Reports Server (NTRS)

Mclaughlin, William I.; Deutsch, Marie J.; Miller, Lanny J.; Wolff, Donna M.; Zawacki, Steven J.

1992-01-01

The three key factors for flight projects - cost, capability, and risk - are examined with respect to their interplay, the uplink process, cost drivers, and risk factors. Scientific objectives are translated into a computer program during the uplink process, and examples are given relating to the Voyager Interstellar Mission, Galileo, and the Comet Rendezvous Asteroid Flyby. The development of a multimission sequence system based on these uplinks is described with reference to specific subsystems such as the pointer and the sequence generator. Operational cost drivers include mission, flight-system, and ground-system complexity, uplink traffic, and work force. Operational risks are listed in terms of the mission operations, the environment, and the mission facilities. The uplink process can be analyzed in terms of software development, and spacecraft operability is shown to be an important factor from the initial stages of spacecraft development.

Observation of freakish-asteroid-discovered-resembles support my idea that many dark comets were arrested and lurked in the solar system after every impaction

NASA Astrophysics Data System (ADS)

Cao, Dayong

2014-03-01

New observations show that some asteroids are looked like comets. http://www.astrowatch.net/2013/11/freakish-asteroid-discovered-resembles.html, http://www.astrowatch.net/2013/11/astronomers-puzzle-over-newfound.html. It supports my idea that ``many dark comets with very special tilted orbits were arrested and lurked in the solar system'' - ``Sun's companion-dark hole seasonal took its dark comets belt and much dark matter to impact near our earth. And some of them probability hit on our earth. So this model kept and triggered periodic mass extinctions on our earth every 25 to 27 million years. After every impaction, many dark comets with very special tilted orbits were arrested and lurked in the solar system. Because some of them picked up many solar matter, so it looked like the asteroids. When the dark hole-Tyche goes near the solar system again, they will impact near planets.'' The idea maybe explains why do the asteroid looks like the comet? Where are the asteroids come from? What relationship do they have with the impactions and extinctions? http://meetings.aps.org/link/BAPS.2011.CAL.C1.7, http://meetings.aps.org/Meeting/CAL12/Event/181168, http://meetings.aps.org/link/BAPS.2013.MAR.H1.267. During 2009 to 2010, I had presented there are many dark comets like dark Asteroids near the orbit of Jupiter in ASP Meetings. In 2010, NASA's WISE found them. http://meetings.aps.org/link/BAPS.2011.APR.K1.17, http://www.nasa.gov/mission_pages/WISE/news/wise20100122.html Avoid Earth Extinction Associ.

BILLIARDS: Baseline Instrumented Lithology Lander, Inspector and Asteroid Redirection Demonstration System

NASA Technical Reports Server (NTRS)

Marcus, Matthew; Sloane, Joshua; Ortiz, Oliver; Barbee, Brent

2015-01-01

BILLIARDS Baseline Instrumented Lithology Lander, Inspector, and Asteroid Redirection Demonstration System Proposed demonstration mission for Billiard-Ball concept Select asteroid pair with natural close approach to minimize cost and complexity Primary Objectives Rendezvous with a small (10m), near Earth (alpha) asteroid Maneuver the alpha asteroid to a collision with a 100m (beta) asteroid Produce a detectable deflection or disruption of the beta asteroid Secondary objectives Contribute knowledge of asteroid composition and characteristics Contribute knowledge of small-body formation Opportunity for international collaboration

Delivery of organics to Mars through asteroid and comet impacts

NASA Astrophysics Data System (ADS)

Frantseva, K.; Mueller, M.; van der Tak, F. F. S.; ten Kate, I. L.; Greenstreet, S.

2017-09-01

Preliminary results show that the asteroid-borne organic flux on Mars is comparable to the IPD rate; asteroids certainly cannot be neglected. Comets, on the other hand, contribute only 0.01% of the IDP-borne rate and can be neglected in the process of organic delivery to Mars.

Space missions to comets

NASA Technical Reports Server (NTRS)

Neugebauer, M. (Editor); Yeomans, D. K. (Editor); Brandt, J. C. (Editor); Hobbs, R. W. (Editor)

1979-01-01

The broad impact of a cometary mission is assessed with particular emphasis on scientific interest in a fly-by mission to Halley's comet and a rendezvous with Tempel 2. Scientific results, speculations, and future plans are discussed.

Can 67P/Churyumov-Gerasimenko become the reference for comet research?

NASA Astrophysics Data System (ADS)

Schulz, R.

2014-07-01

After its discovery in 1969, comet 67P/Churyumov-Gerasimenko went almost unnoticed through another five perihelion passages until the year 2003, when it suddenly became the new target of the first comet rendezvous mission, Rosetta. Today, 11 years and 1.5 apparitions later, it has become one of the few Jupiter-family comets that were monitored along its entire orbit, even near aphelion. Huge effort was spent in determining its characteristics. Observations obtained by the largest and most sophisticated telescopes on the Earth and in space were combined with dedicated modelling approaches in order to be best prepared for the space mission. Therefore, at this point time, we have basically determined as much as is achievable for a comet of this brightness without visiting it by spacecraft. A summary of what we already know about 67P/Churyumov-Gerasimenko, hence what we could in principle also determine for the ensemble of Jupiter-family comets, will be provided. The information expected to become available after the comet rendezvous will then be discussed particularly in view of whether and how it can be transferred to other comets for which only remote observations can be collected in the near future.

Mosaic of CCDs to Survey for Asteroids and Comets

NASA Technical Reports Server (NTRS)

McMillan, Robert S.

2002-01-01

Spacewatch searches for asteroids and comets ranging in location from near-Earth space to regions beyond the orbit of Neptune. We are studying Earth-approaching asteroids, main belt asteroids, comets, Centaurs, and TNOs, as well as the interrelationships of these classes and their bearing on the origin and evolution of the solar system. Spacewatch is described at http://www. lpl. arizona. edu/spacewatch/index.html. The Spacewatch Project has been discovering Earth-approaching asteroids (EAs) steadily and has used the results aggressively to estimate the statistical properties of the EA population. This grant funded Spacewatch to develop and implement a mosaic of CCD imaging detectors for the 0.9-m telescope, to increase that telescope's rate of coverage of sky area while preserving its limiting magnitude.

Expert system isssues in automated, autonomous space vehicle rendezvous

NASA Technical Reports Server (NTRS)

Goodwin, Mary Ann; Bochsler, Daniel C.

1987-01-01

The problems involved in automated autonomous rendezvous are briefly reviewed, and the Rendezvous Expert (RENEX) expert system is discussed with reference to its goals, approach used, and knowledge structure and contents. RENEX has been developed to support streamlining operations for the Space Shuttle and Space Station program and to aid definition of mission requirements for the autonomous portions of rendezvous for the Mars Surface Sample Return and Comet Nucleus Sample return unmanned missions. The experience with REMEX to date and recommendations for further development are presented.

A CubeSat Asteroid Mission: Design Study and Trade-Offs

NASA Technical Reports Server (NTRS)

Landis, Geoffrey A.; Oleson, Steven R.; McGuire, Melissa; Hepp, Aloysius; Stegeman, James; Bur, Mike; Burke, Laura; Martini, Michael; Fittje, James E.; Kohout, Lisa;

Spectroscopy of asteroids in unusual orbits

NASA Technical Reports Server (NTRS)

Cochran, W. D.; Cochran, A. L.; Barker, E. S.

1986-01-01

Medium-resolution spectroscopy of a collection of nonmain-belt asteroids has been obtained in order to search for possible cometlike spectral features. The asteroids include nine earth approachers, two Trojans, and the unusual object 2060 Chiron. All spectra were obtained and reduced in the same manner as comet data in the McDonald Observatory Faint Comet Survey. No indication of cometary activity was found in any of the asteroids observed.

Science Planning for the TROPIX Mission

NASA Technical Reports Server (NTRS)

Russell, C. T.

1998-01-01

The objective of the study grant was to undertake the planning needed to execute meaningful solar electric propulsion missions in the magnetosphere and beyond. The first mission examined was the Transfer Orbit Plasma Investigation Experiment (TROPIX) mission to spiral outward through the magnetosphere. The next mission examined was to the moon and an asteroid. Entitled Diana, it was proposed to NASA in October 1994. Two similar missions were conceived in 1996 entitled CNR for Comet Nucleus Rendezvous and MBAR for Main Belt Asteroid Rendezvous. The latter mission was again proposed in 1998. All four of these missions were unsuccessfully proposed to the NASA Discovery program. Nevertheless we were partially successful in that the Deep Space 1 (DS1) mission was eventually carried out nearly duplicating our CNR mission. Returning to the magnetosphere we studied and proposed to the Medium Class Explorer (MIDEX) program a MidEx mission called TEMPEST, in 1995. This mission included two solar electric spacecraft that spiraled outward in the magnetosphere: one at near 900 inclination and one in the equatorial plane. This mission was not selected for flight. Next we proposed a single SEP vehicle to carry Energetic Neutral Atom (ENA) imagers and inside observations to complement the IMAGE mission providing needed data to properly interpret the IMAGE data. This mission called SESAME was submitted unsuccessfully in 1997. One proposal was successful. A study grant was awarded to examine a four spacecraft solar electric mission, named Global Magnetospheric Dynamics. This study was completed and a report on this mission is attached but events overtook this design and a separate study team was selected to design a classical chemical mission as a Solar Terrestrial Probe. Competing proposals such as through the MIDEX opportunity were expressly forbidden. A bibliography is attached.

Autonomous rendezvous and docking: A commercial approach to on-orbit technology validation

NASA Technical Reports Server (NTRS)

Tchoryk, Peter, Jr.; Whitten, Raymond P.

1991-01-01

SpARC, in conjunction with its corporate affiliates, is planning an on-orbit validation of autonomous rendezvous and docking (ARD) technology. The emphasis in this program is to utilize existing technology and commercially available components wherever possible. The primary subsystems to be validated by this demonstration include GPS receivers for navigation, a video-based sensor for proximity operations, a fluid connector mechanism to demonstrate fluid resupply capability, and a compliant, single-point docking mechanism. The focus for this initial experiment will be ELV based and will make use of two residual Commercial Experiment Transporter (COMET) service modules. The first COMET spacecraft will be launched in late 1992 and will serve as the target vehicle. After the second COMET spacecraft has been launched in late 1994, the ARD demonstration will take place. The service module from the second COMET will serve as the chase vehicle.

Trajectory design for an ion drive asteroids rendezvous mission launched into an Ariane geostationary transfer orbit

NASA Astrophysics Data System (ADS)

Pietrass, A. E.

1984-08-01

AMSAT has conceived an asteroid rendezvous mission which would consist of an Ariane-launched, 3-axis-stabilized, 350-kg spacecraft utilizing both mercury and solar electric ion propulsion. The spacecraft is to be equipped with a science instrument platform with a mass of approximately 30 to 50 kg. Practically uninterrupted earth departure opportunities are found for targets such as 4 Vesta, 8 Flora, and 19 Fortuna from 1986 through 1988. The 7 to 8 year mission would allow for a second rendezvous of 4 Vesta, and marginal additional fuel would make close flybys of targets feasible. Through the use of parameter optimization techniques, trajectories can be generated and the inclusion of constraints due to spacecraft techology, tour design, and navigation can be facilitated.

Estimating the Mass of Asteroid 433 Eros During the Near Spacecraft Flyby

NASA Technical Reports Server (NTRS)

Yeomans, D.; Antreasian, P.; Cheng, A.; Dunham, D.; Farquhar, R.; Gaskell, R.; Giorgini, J.; Helfrich, C.; Konopliv, A.; McAdams, J.;

Report of the Terrestrial Bodies Science Working Group. Volume 6: The asteroids

NASA Technical Reports Server (NTRS)

Chapman, C. R.; Johnson, T. V.; Mccord, T. B.

1977-01-01

Earth-based astronomical observations and laboratory analysis of meteorites provide the only scientific data available on asteroids. These data are summarized and subjects for future investigations are explored. The measurements required for potential missions are discussed and concepts for a multi-asteroid rendezvous mission in the mid-1980's are outlined.

Asteroid Impact Mission (aim) & Deflection Assessment: AN Opportunity to Understand Impact Dynamics and Modelling

NASA Astrophysics Data System (ADS)

Galvez, A.; Carnelli, I.; Fontaine, M.; Corral Van Damme, C.

2012-09-01

ESA's Future Preparation and Strategic Studies Office has carried out the Asteroid Impact Mission (AIM) study with the objective of defining an affordable and fully independent mission element that ESA could contribute to an Asteroid Impact Deflection Assessment campaign (AIDA), a joint effort of ESA, JHU/APL, NASA, OCA and DLR. The mission design foresees two independent spacecraft, one impactor (DART) and one rendezvous probe (AIM). The target of this mission is the binary asteroid system (65803) Didymos (1996 GT): one spacecraft, DART, would impact the secondary of the Didymos binary system while AIM would observe and measure any the change in the relative orbit. For this joint project, the timing of the experiment is set (maximum proximity of the target to Earth allowing for ground-based characterisation of the experiment) but the spacecraft are still able to pursue their missions fully independently. This paper describes in particular the AIM rendezvous mission concept.

Radioisotope Electric Propulsion (REP) for Selected Interplanetary Science Missions

NASA Technical Reports Server (NTRS)

Oh, David; Bonfiglio, Eugene; Cupples, Mike; Belcher, Jeremy; Witzberger, Kevin; Fiehler, Douglas; Artis, Gwen

2005-01-01

This viewgraph presentation analyzes small body targets (Trojan Asteroids), Medium Outer Planet Class (Jupiter Polar Orbiter with Probes), and Main Belt Asteroids and Comets (Comet Surface Sample Return), for Radioisotope Electric Propulsion (REP).

Two-phase framework for near-optimal multi-target Lambert rendezvous

NASA Astrophysics Data System (ADS)

Bang, Jun; Ahn, Jaemyung

2018-03-01

This paper proposes a two-phase framework to obtain a near-optimal solution of multi-target Lambert rendezvous problem. The objective of the problem is to determine the minimum-cost rendezvous sequence and trajectories to visit a given set of targets within a maximum mission duration. The first phase solves a series of single-target rendezvous problems for all departure-arrival object pairs to generate the elementary solutions, which provides candidate rendezvous trajectories. The second phase formulates a variant of traveling salesman problem (TSP) using the elementary solutions prepared in the first phase and determines the final rendezvous sequence and trajectories of the multi-target rendezvous problem. The validity of the proposed optimization framework is demonstrated through an asteroid exploration case study.

Physical Mechanism of Comet (and Asteroid) Outbursts: The Movie

NASA Astrophysics Data System (ADS)

Hartmann, W. K.

2015-07-01

A film made during impact experiments at NASA Ames illustrates a mechanism in which regolith can become gas charged and then erupt to create outbursts as observed on comets (and "asteroids" such as 2060 Chiron).

Stretched Lens Array Photovoltaic Concentrator Technology Developed

NASA Technical Reports Server (NTRS)

Piszczor, Michael F., Jr.; O'Neill, Mark J.

2004-01-01

Solar arrays have been and continue to be the mainstay in providing power to nearly all commercial and government spacecraft. Light from the Sun is directly converted into electrical energy using solar cells. One way to reduce the cost of future space power systems is by minimizing the size and number of expensive solar cells by focusing the sunlight onto smaller cells using concentrator optics. The stretched lens array (SLA) is a unique concept that uses arched Fresnel lens concentrators to focus sunlight onto a line of high-efficiency solar cells located directly beneath. The SLA concept is based on the Solar Concentrator Array with Refractive Linear Element Technology (SCARLET) design that was used on NASA's New Millennium Deep Space 1 mission. The highly successful asteroid/comet rendezvous mission (1998 to 2001) demonstrated the performance and long-term durability of the SCARLET/SLA solar array design and set the foundation for further improvements to optimize its performance.

Design concepts and performance of NASA X-band transponder (DST) for deep space spacecraft applications

NASA Technical Reports Server (NTRS)

Mysoor, Narayan R.; Perret, Jonathan D.; Kermode, Arthur W.

1991-01-01

The design concepts and measured performance characteristics of an X band (7162 MHz/8415 MHz) breadboard deep space transponder (DST) for future spacecraft applications, with the first use scheduled for the Comet Rendezvous Asteroid Flyby (CRAF) and Cassini missions in 1995 and 1996, respectively. The DST consists of a double conversion, superheterodyne, automatic phase tracking receiver, and an X band (8415 MHz) exciter to drive redundant downlink power amplifiers. The receiver acquires and coherently phase tracks the modulated or unmodulated X band (7162 MHz) uplink carrier signal. The exciter phase modulates the X band (8415 MHz) downlink signal with composite telemetry and ranging signals. The receiver measured tracking threshold, automatic gain control static phase error, and phase jitter characteristics of the breadboard DST are in good agreement with the expected performance. The measured results show a receiver tracking threshold of -158 dBm and a dynamic signal range of 88 dB.

An X-band spacecraft transponder for deep space applications - Design concepts and breadboard performance

NASA Technical Reports Server (NTRS)

Mysoor, Narayan R.; Perret, Jonathan D.; Kermode, Arthur W.

1992-01-01

The design concepts and measured performance characteristics are summarized of an X band (7162 MHz/8415 MHz) breadboard deep space transponder (DSP) for future spacecraft applications, with the first use scheduled for the Comet Rendezvous Asteroid Flyby (CRAF) and Cassini missions in 1995 and 1996, respectively. The DST consists of a double conversion, superheterodyne, automatic phase tracking receiver, and an X band (8415 MHz) exciter to drive redundant downlink power amplifiers. The receiver acquires and coherently phase tracks the modulated or unmodulated X band (7162 MHz) uplink carrier signal. The exciter phase modulates the band (8415 MHz) downlink signal with composite telemetry and ranging signals. The receiver measured tracking threshold, automatic gain control, static phase error, and phase jitter characteristics of the breadboard DST are in good agreement with the expected performance. The measured results show a receiver tracking threshold of -158 dBm and a dynamic signal range of 88 dB.

Results of the JIMO Follow-on Destinations Parametric Studies

NASA Technical Reports Server (NTRS)

Noca, Muriel A.; Hack, Kurt J.

2005-01-01

NASA's proposed Jupiter Icy Moon Orbiter (JIMO) mission currently in conceptual development is to be the first one of a series of highly capable Nuclear Electric Propulsion (NEP) science driven missions. To understand the implications of a multi-mission capability requirement on the JIMO vehicle and mission, the NASA Prometheus Program initiated a set of parametric high-level studies to be followed by a series of more in-depth studies. The JIMO potential follow-on destinations identified include a Saturn system tour, a Neptune system tour, a Kuiper Belt Objects rendezvous, an Interstellar Precursor mission, a Multiple Asteroid Sample Return and a Comet Sample Return. This paper shows that the baseline JIMO reactor and design envelop can satisfy five out of six of the follow-on destinations. Flight time to these destinations can significantly be reduced by increasing the launch energy or/and by inserting gravity assists to the heliocentric phase.

Analysis of the Organic Matter in Interplanetary Dust Particles: Clues to the Organic Matter in Comets, Asteroids, and Interstellar Grains

NASA Technical Reports Server (NTRS)

Flynn, G. J.; Keller, L. P.

2003-01-01

Reflection spectroscopy suggests the C- , P-, and D-types of asteroids contain abundant carbon, but these Vis-nearIR spectra are featureless, providing no information on the type(s) of carbonaceous matter. Infrared spectroscopy demonstrates that organic carbon is a significant component in comets and as grains or grain coatings in the interstellar medium. Most of the interplanetary dust particles (IDPs) recovered from the Earth s stratosphere are believed to be fragments from asteroids or comets, thus characterization of the carbon in IDPs provides the opportunity to determine the type(s) and abundance of organic matter in asteroids and comets. Some IDPs exhibit isotopic excesses of D and N-15, indicating the presence of interstellar material. The characterization of the carbon in these IDPs, and particularly any carbon spatially associated with the isotopic anomalies, provides the opportunity to characterize interstellar organic matter.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Yoonyoung; Ishiguro, Masateru; Usui, Fumihiko

We investigated the population of asteroids in comet-like orbits using available asteroid size and albedo catalogs of data taken with the Infrared Astronomical Satellite, AKARI, and the Wide-field Infrared Survey Explorer on the basis of their orbital properties (i.e., the Tisserand parameter with respect to Jupiter, T{sub J}, and the aphelion distance, Q). We found that (1) there are 123 asteroids in comet-like orbits by our criteria (i.e., Q > 4.5 AU and T{sub J} < 3), (2) 80% of them have low albedo, p{sub v} < 0.1, consistent with comet nuclei, (3) the low-albedo objects among them have amore » size distribution shallower than that of active comet nuclei, that is, the power index of the cumulative size distribution is around 1.1, and (4) unexpectedly, a considerable number (i.e., 25 by our criteria) of asteroids in comet-like orbits have high albedo, p{sub v} > 0.1. We noticed that such high-albedo objects mostly consist of small (D < 3 km) bodies distributed in near-Earth space (with perihelion distance of q < 1.3 AU). We suggest that such high-albedo, small objects were susceptible to the Yarkovsky effect and drifted into comet-like orbits via chaotic resonances with planets.« less

Asteroid-comet continuum objects in the solar system.

PubMed

Hsieh, Henry H

2017-07-13

In this review presented at the Royal Society meeting, 'Cometary science after Rosetta', I present an overview of studies of small solar system objects that exhibit properties of both asteroids and comets (with a focus on so-called active asteroids). Sometimes referred to as 'transition objects', these bodies are perhaps more appropriately described as 'continuum objects', to reflect the notion that rather than necessarily representing actual transitional evolutionary states between asteroids and comets, they simply belong to the general population of small solar system bodies that happen to exhibit a continuous range of observational, physical and dynamical properties. Continuum objects are intriguing because they possess many of the properties that make classical comets interesting to study (e.g. relatively primitive compositions, ejection of surface and subsurface material into space where it can be more easily studied, and orbital properties that allow us to sample material from distant parts of the solar system that would otherwise be inaccessible), while allowing us to study regions of the solar system that are not sampled by classical comets.This article is part of the themed issue 'Cometary science after Rosetta'. © 2017 The Author(s).

Planetary Defense: Are we currently looking for our keys under the lamp post?

NASA Astrophysics Data System (ADS)

Nuth, J. A., III; Barbee, B.; Leung, R. Y.

2016-12-01

Planetary Defense is a serious and important endeavor and the approach taken to date is a sensible beginning. Finding and cataloging all potentially hazardous asteroids and supporting research into relevant topics required to divert such a threat to our home planet is a necessary, but far from sufficient set of activities required to ensure the survival of our species. Concentrating our efforts on the asteroid threat is relatively easy. Most asteroids move in near-circular orbits, are relatively close to the ecliptic plane and are likely to be detected as hazards many decades in advance of a potential impact. The single most likely problem that will be encountered in deflecting such a threat will be developing the political will to fund the project while there is still ample time for multiple deflection techniques to be applied successfully. While asteroid threats can be mitigated, comets are the invisible danger lurking in the vast, dark parking lot that is the outer solar system. Very few comets falling into the inner solar system will be detected more than two years before their arrival: refinement of a new comet's trajectory requires months of observation before its hazard potential can be realistically assessed and knowledge of the composition, mass and shape of the body cannot be refined sufficiently to design a deflection campaign without much more observational effort. To make matters worse, because of the highly elliptical orbits of most new comets, some of which can be far out of the ecliptic plane while a few can even be in retrograde orbits, the impact velocity of a typical comet will be significantly higher than that of an asteroid. If this increase is only a factor of two, then a typical comet carries four times the impact energy of an asteroid of similar size, though much higher multipliers are possible. The distribution of meteor stream velocities can be examined to place bounds on this threat. Finally, the time required to assemble and launch an asteroid deflection mission starting from scratch and with a high probability of success could exceed three years from mission approval. Based on the recent passage of Comet Siding Spring one must therefore conclude that a successful comet deflection mission must begin well before a hazardous comet is even detected, much less characterized as a significant threat.

Asteroid and Comet Census from WISE

NASA Image and Video Library

2010-10-04

This frame from a video demonstrates how NASA Wide-field Infrared Survey Explorer surveys asteroids and comets in the solar system. Perspective shown here is looking down from high above Earth North Pole, a kind of bird eye view of the solar system.

Physical characteristics of Comet Nucleus C/2001 OG 108 (LONEOS)

NASA Astrophysics Data System (ADS)

Abell, Paul A.; Fernández, Yanga R.; Pravec, Petr; French, Linda M.; Farnham, Tony L.; Gaffey, Michael J.; Hardersen, Paul S.; Kušnirák, Peter; Šarounová, Lenka; Sheppard, Scott S.; Narayan, Gautham

2005-12-01

A detailed description of the Halley-type Comet C/2001 OG 108 (LONEOS) has been derived from visible, near-infrared, and mid-infrared observations obtained in October and November 2001. These data represent the first high-quality ground-based observations of a bare Halley-type comet nucleus and provide the best characterization of a Halley-type comet other than 1P/Halley itself. Analysis of time series photometry suggests that the nucleus has a rotation period of 57.2±0.5 h with a minimum nuclear axial ratio of 1.3, a phase-darkening slope parameter G of -0.01±0.10, and an estimated H=13.05±0.10. The rotation period of C/2001 OG 108 is one of the longest observed among comet nuclei. The V- R color index for this object is measured to be 0.46±0.02, which is virtually identical to that of other cometary nuclei and other possible extinct comet candidates. Measurements of the comet's thermal emission constrain the projected elliptical nuclear radii to be 9.6±1.0 km and 7.4±1.0 km, which makes C/2001 OG 108 one of the larger cometary nuclei known. The derived geometric albedo in V-band of 0.040±0.010 is typical for comet nuclei. Visible-wavelength spectrophotometry and near-infrared spectroscopy were combined to derive the nucleus's reflectance spectrum over a 0.4 to 2.5 μm wavelength range. These measurements represent one of the few nuclear spectra ever observed and the only known spectrum of a Halley-type comet. The spectrum of this comet nucleus is very nearly linear and shows no discernable absorption features at a 5% detection limit. The lack of any features, especially in the 0.8 to 1.0 μm range such as are seen in the spectra of carbonaceous chondrite meteorites and many low-albedo asteroids, is consistent with the presence of anhydrous rather than hydrous silicates on the surface of this comet. None of the currently recognized meteorites in the terrestrial collections have reflectance spectra that match C/2001 OG 108. The near-infrared spectrum, the geometric albedo, and the visible spectrophotometry all indicate that C/2001 OG 108 has spectral properties analogous to the D-type, and possibly P-type asteroids. Comparison of the measured albedo and diameter of C/2001 OG 108 with those of Damocloid asteroids reveals similarities between these asteroids and this comet nucleus, a finding which supports previous dynamical arguments that Damocloid asteroids could be composed of cometary-like materials. These observations are also consistent with findings that two Jupiter-family comets may have spectral signatures indicative of D-type asteroids. C/2001 OG 108 probably represents the transition from a typical active comet to an extinct cometary nucleus, and, as a Halley-type comet, suggests that some comets originating in the Oort cloud can become extinct without disintegrating. As a near-Earth object, C/2001 OG 108 supports the suggestion that some fraction of the near-Earth asteroid population consists of extinct cometary nuclei.

Castalia - A Mission to a Main Belt Comet

NASA Astrophysics Data System (ADS)

Jones, G. H.; Snodgrass, C.

2015-10-01

Main Belt Comets (MBCs), or Active Asteroids, constitute a newly identified class of solar system objects. They have stable, asteroid-like orbits and some exhibit a recurrent comet-like appearance. It is believed that they survived the age of the solarsystem in a dormant state and that their current ice sublimation driven activity only began recently. Buried water ice is the only volatile expected to survive under an insulating surface. Excavation by an impact can expose the ice and trigger the start of MBC activity. We present the case for a mission to one of these objects. The specific science goals of the Castalia mission are: 1. Characterize a new Solar System family, the MBCs, by in-situ investigation 2. Understand the physics of activity on MBCs 3. Directly sample water in the asteroid belt and test if MBCs are a viable source for Earth's water 4. Use the observed structure of an MBC as a tracer of planetary system formation and evolution. These goals can be achieved by a spacecraft designed to rendezvous with and orbit an MBC for a time interval of some months, arriving before the active period for mapping and then sampling the gas and dust released during the active phase. Given the low level of activity of MBCs, and the expectation that their activity comes from only a localized patch on the surface, the orbiting spacecraft will have to be able to maintain a very close orbit over extended periods - the Castalia plan envisages an orbiter capable of 'hovering' autonomously at distances of only a few km from the surface of the MBC. The strawman payload comprises a Visible and near-infrared spectral imager, Thermal infrared imager, Radio science,Subsurface radar, Dust impact detector, Dust composition analyser, Neutral/ion mass spectrometer, Magnetometer, and Plasma package. In addition to this, a surface science package is being considered. At the moment, MBC 133P/Elst Pizarro is the bestknown target for such a mission. A design study for the Castalia mission has been carried out in partnership between the science team, DLR and OHB Systems. This study looked at possible missions to 133P with launch dates around 2025, and found that this, and backup MBC targets, are reachable by an ESA M-class mission. More details are available at http://bit.ly/mbcmission

Rosetta enters hibernation

NASA Astrophysics Data System (ADS)

Ferri, Paolo; Accomazzo, Andrea; Hubault, Armelle; Lodiot, Sylvain; Pellon-Bailon, Jose-Luis; Porta, Roberto

2012-10-01

The International Rosetta Mission was launched on 2nd March 2004 on its 10 years journey to comet 67P/Churyumov-Gerasimenko. Rosetta will reach the comet in 2014, orbit it for about 1.5 years down to distances of a few kilometres and deliver the Lander Philae onto its surface. Following the fly-by of Asteroid (21-)Lutetia in 2010, Rosetta continued its travel towards the planned comet encounter in 2014. In this phase Rosetta became the solar-powered spacecraft that reached the largest Sun distances in history of spaceflight, up to an aphelion at 5.3 AU in October 2012. At distances above 4.5 AU the spacecraft's solar generator power is not sufficient to keep all spacecraft systems active. Therefore in June 2011 the spacecraft was spun up to provide gyroscopic stabilisation, and most of its on-board units, including those used for attitude control and communications, were switched off. Over this "hibernation" phase of about 2.5 years the spacecraft will keep a minimum of autonomy active to ensure maintenance of safe thermal conditions. After Lutetia fly-by, flight controllers had to tackle two anomalies that had significant impacts on the mission operations. A leak in the reaction control subsystem was confirmed and led to the re-definition of the operational strategy to perform the comet rendezvous manoeuvres planned for 2011 and 2014. Anomalous jumps detected in the estimated friction torque of two of the four reaction wheels used for attitude control forced the rapid adoption of measures to slow down the wheels degradation. This included in-flight re-lubrication activities and changes in the wheels operational speed regime. Once the troubleshooting of the two anomalies was completed, and the related operational scenarios were implemented, the first large (790 m/s) comet rendezvous manoeuvre was executed, split into several long burns in January and February 2011. The second burn was unexpectedly interrupted due to the anomalous behaviour of two thrusters, causing attitude off-pointing. Flight controllers modified the thrusters operation parameters in the on-board software and managed to re-start the sequence of burns and successfully complete the manoeuvre. After the manoeuvre, preparation for the critical spin-up and hibernation entry activities, planned for June 2011, began. This paper presents the activities carried out on Rosetta in the final year before hibernation entry. The major anomalies and the related troubleshooting and workaround solutions are detailed. Lessons learned from the operation of the first spacecraft operating with solar power at Jupiter-like distances from the Sun are presented and discussed.

New Research by CCD Scanning for Comets and Asteroids

NASA Technical Reports Server (NTRS)

Gehrels, Tom; McMillan, Robert S.

1997-01-01

The purpose of Spacewatch is to explore the various populations of small objects within the solar system. Spacewatch provides data for studies of comets and asteroids, finds potential targets for space missions, and provides information on the environmental problem of possible impacts. Moving objects are discovered by scanning the sky with charge-coupled devices (CCDs) on the 0.9-meter Spacewatch Telescope of the University of Arizona on Kitt Peak. Each Spacewatch scan consists of three drift scan passes over an area of sky using a CCD filtered to a bandpass of 0.5-1.0 microns (approximately V+R+I with peak sensitivity at 0.7 micron). The effective exposure time for each pass is 143 seconds multiplied by the secant of the declination. We have been finding some 30,000 new asteroids per year and applying their statistics to the study of the collisional history of the solar system. As of the end of the observing run of Nov. 1997, Spacewatch had found a total of 153 Near-Earth Asteroids (NEAs) and 8 new comets since the project began in the 1980s, and had recovered one lost comet. The total number of NEAs found by Spacewatch big enough to be hazardous if they were to impact the Earth is 36. Spacewatch is also efficient in recovery of known comets and has detected and reported positions for more than 137,000 asteroids, mostly new ones in the main belt, including more than 16,000 asteroids designated by the Minor Planet Center (MPC).

A Delta-V map of the known Main Belt Asteroids

NASA Astrophysics Data System (ADS)

Taylor, Anthony; McDowell, Jonathan C.; Elvis, Martin

2018-05-01

With the lowered costs of rocket technology and the commercialization of the space industry, asteroid mining is becoming both feasible and potentially profitable. Although the first targets for mining will be the most accessible near Earth objects (NEOs), the Main Belt contains 106 times more material by mass. The large scale expansion of this new asteroid mining industry is contingent on being able to rendezvous with Main Belt asteroids (MBAs), and so on the velocity change required of mining spacecraft (delta-v). This paper develops two different flight burn schemes, both starting from Low Earth Orbit (LEO) and ending with a successful MBA rendezvous. These methods are then applied to the ∼700,000 asteroids in the Minor Planet Center (MPC) database with well-determined orbits to find low delta-v mining targets among the MBAs. There are 3986 potential MBA targets with a delta-v < 8 km s-1 , but the distribution is steep and reduces to just 4 with delta-v < 7 km s-1. The two burn methods are compared and the orbital parameters of low delta-v MBAs are explored.

Potential Jupiter-Family comet contamination of the main asteroid belt

NASA Astrophysics Data System (ADS)

Hsieh, Henry H.; Haghighipour, Nader

2016-10-01

We present the results of "snapshot" numerical integrations of test particles representing comet-like and asteroid-like objects in the inner Solar System aimed at investigating the short-term dynamical evolution of objects close to the dynamical boundary between asteroids and comets as defined by the Tisserand parameter with respect to Jupiter, TJ (i.e., TJ = 3). As expected, we find that TJ for individual test particles is not always a reliable indicator of initial orbit types. Furthermore, we find that a few percent of test particles with comet-like starting elements (i.e., similar to those of Jupiter-family comets) reach main-belt-like orbits (at least temporarily) during our 2 Myr integrations, even without the inclusion of non-gravitational forces, apparently via a combination of gravitational interactions with the terrestrial planets and temporary trapping by mean-motion resonances with Jupiter. We estimate that the fraction of real Jupiter-family comets occasionally reaching main-belt-like orbits on Myr timescales could be on the order of ∼ 0.1-1%, although the fraction that remain on such orbits for appreciable lengths of time is certainly far lower. For this reason, the number of JFC-like interlopers in the main-belt population at any given time is likely to be small, but still non-zero, a finding with significant implications for efforts to use apparently icy yet dynamically asteroidal main-belt comets as tracers of the primordial distribution of volatile material in the inner Solar System. The test particles with comet-like starting orbital elements that transition onto main-belt-like orbits in our integrations appear to be largely prevented from reaching low eccentricity, low inclination orbits, suggesting that the real-world population of main-belt objects with both low eccentricities and inclinations may be largely free of this potential occasional Jupiter-family comet contamination. We therefore find that low-eccentricity, low-inclination main-belt comets may provide a more reliable means for tracing the primordial ice content of the main asteroid belt than the main-belt comet population as a whole.

Analyses of the P/Wild 2 Images from STARDUST

NASA Technical Reports Server (NTRS)

Duxbury, Thomas C.

2004-01-01

This viewgraph presentation reviews the design of the Stardust spacecraft, and the trajectory that took it to rendezvous with the comet, Wild-2. Included are views of the comet, and comparisons with other astronomical bodies. Close up views show size, shape and orientation.

Spacecraft Mission Design for the Mitigation of the 2017 PDC Hypothetical Asteroid Threat

NASA Technical Reports Server (NTRS)

Barbee, Brent W.; Sarli, Bruno V.; Lyzhoft, Josh; Chodas, Paul W.; Englander, Jacob A.

2017-01-01

This paper presents a detailed mission design analysis results for the 2017 Planetary Defense Conference (PDC) Hypothetical Asteroid Impact Scenario, documented at https:cneos.jpl.nasa.govpdcspdc17. The mission design includes campaigns for both reconnaissance (flyby or rendezvous) of the asteroid (to characterize it and the nature of the threat it poses to Earth) and mitigation of the asteroid, via kinetic impactor deflection, nuclear explosive device (NED) deflection, or NED disruption. Relevant scenario parameters are varied to assess the sensitivity of the design outcome, such as asteroid bulk density, asteroid diameter, momentum enhancement factor, spacecraft launch vehicle, and mitigation system type. Different trajectory types are evaluated in the mission design process from purely ballistic to those involving optimal midcourse maneuvers, planetary gravity assists, and/or low-thrust solar electric propulsion. The trajectory optimization is targeted around peak deflection points that were found through a novel linear numerical technique method. The optimization process includes constrain parameters, such as Earth departure date, launch declination, spacecraft, asteroid relative velocity and solar phase angle, spacecraft dry mass, minimum/maximum spacecraft distances from Sun and Earth, and Earth-spacecraft communications line of sight. Results show that one of the best options for the 2017 PDC deflection is solar electric propelled rendezvous mission with a single spacecraft using NED for the deflection.

Autonomous rendezvous and docking: A commercial approach to on-orbit technology validation

NASA Technical Reports Server (NTRS)

Tchoryk, Peter, Jr.; Dobbs, Michael E.; Conrad, David J.; Apley, Dale J.; Whitten, Raymond P.

1991-01-01

The Space Automation and Robotics Center (SpARC), a NASA-sponsored Center for the Commercial Development of Space (CCDS), in conjunction with its corporate affiliates, is planning an on-orbit validation of autonomous rendezvous and docking (ARD) technology. The emphasis in this program is to utilize existing technology and commercially available components whenever possible. The primary subsystems that will be validated by this demonstration include GPS receivers for navigation, a video-based sensor for proximity operations, a fluid connector mechanism to demonstrate fluid resupply capability, and a compliant, single-point docking mechanism. The focus for this initial experiment will be expendable launch vehicle (ELV) based and will make use of two residual Commercial Experiment Transporter (COMET) service modules. The first COMET spacecraft will be launched in late 1992 and will serve as the target vehicle. The ARD demonstration will take place in late 1994, after the second COMET spacecraft has been launched. The service module from the second COMET will serve as the chase vehicle.

Rosetta rendezvous and CONSERT operations in 2014: A chimeric surface model of 67P/Churyumov Gerasimenko

NASA Astrophysics Data System (ADS)

Herique, Alain; Lasue, Jéremie; Rogez, Yves; Zine, Sonia; Kofman, Wlodek

2012-07-01

In 2014 the European Space Agency's Rosetta probe will rendezvous with the comet 67P/Churyumov Gerasimenko (67P) and the Philae Lander will land on the surface of the nucleus. Following the landing, the COmet Nucleus Sounding Experiment by Radiowave Transmission (CONSERT) radar will perform the tomography of the nucleus by measuring radiowave propagation through the comet between the Lander and the orbiter. Preparation for these operations, in particular the development and validation of simulation software, requires a shape model of the surface of 67P. The complexity of this model should reflect the environmental conditions that will be found in 2014. In this paper, we show that existing models of 67P are not of a sufficiently high resolution to constitute interesting test cases. Following a review of current shape models for other comets, we propose a composite which is a hybrid of the 67P and 81P/Wild 2 models.

A population of comets in the main asteroid belt.

PubMed

Hsieh, Henry H; Jewitt, David

2006-04-28

Comets are icy bodies that sublimate and become active when close to the Sun. They are believed to originate in two cold reservoirs beyond the orbit of Neptune: the Kuiper Belt (equilibrium temperatures of approximately 40 kelvin) and the Oort Cloud (approximately 10 kelvin). We present optical data showing the existence of a population of comets originating in a third reservoir: the main asteroid belt. The main-belt comets are unlike the Kuiper Belt and Oort Cloud comets in that they likely formed where they currently reside and may be collisionally activated. The existence of the main-belt comets lends new support to the idea that main-belt objects could be a major source of terrestrial water.

The study of the physics of cometary nuclei

NASA Technical Reports Server (NTRS)

Whipple, F. L.

1985-01-01

The development and utilization of an optimized computer program to analyze orbital stabilization by repeated calculations is presented. The stability of comets in the Opik-Oort Cloud about the Sun against perturbations by the Galactic center involve the same basic type of calculation. The supposed persistence of these bodies in orbits over the life of the solar system, depends upon the stability of bodies of negligible mass in orbits around a body whose mass is small compared to the central mass about which they revolve. The question remains of preferential orientation of extremely eccentric comet orbits, possibly to explain the asymmetry observed among new comet motions. A third application of the computing programs is suited to meteoroids that may exist in orbits about asteroids and that may endanger science spacecraft making flybys too near to asteroids. As in the double-comet case, solar activity and solar gravitational perturbations limit the attendance to an asteroid by small meteroids in their orbits. It is found that the mass distances planned for asteroid fly-bys are adequate.

Comets: Data, problems, and objectives

NASA Technical Reports Server (NTRS)

Whipple, F. L.

1977-01-01

A highly abridged review of new relevant results from the observations of Comet Kohoutek is followed by an outline summary of our basic knowledge concerning comets, both subjects being confined to data related to the nature and origin of comets rather than the phenomena (for example, plasma phenomena are omitted). The discussion then centers on two likely places of cometary origin in the developing solar system, the proto-Uranus-Neptune region versus the much more distant fragmented interstellar cloud region, now frequented by comets of the Opik-Oort cloud. The Comet Kohoutek results add new insights, particularly with regard to the parent molecules and the nature of meteoric solids in comets, to restrict the range of the physical circumstances of comet formation. A few fundamental and outstanding questions are asked, and a plea made for unmanned missions to comets and asteroids in order to provide definitive answers as to the nature and origin of comets, asteroids, and the solar system generally.

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.

The Rotational Properties of Multi-tailed Asteroid P/2013 P5

NASA Astrophysics Data System (ADS)

Gustafsson, Annika; Moskovitz, Nicholas; Levine, Stephen

2014-11-01

To date, there are twelve known celestial bodies in the Solar System, labeled Main Belt Comets (e.g. Hsieh & Jewitt, 2006) or Active Asteroids (Jewitt, 2012) that exhibit both asteroid and comet-like properties. Among them is P/2013 P5, a comet-asteroid transition object discovered by PAN-STARRS in August 2013. Observations made with the Hubble Space Telescope in September 2013 revealed that P/2013 P5 appears to have six comet-like dust tails. Jewitt et al. (2013) concluded that this extraordinary structure and activity cannot be explained by traditional near-surface ice sublimation or collision events ejecting particles from the asteroid’s surface. Instead, the most likely explanation is that this unusual object has been spun-up by YORP torques to a critical limit that has resulted in the rotational disruption of the asteroid causing the unique six-tail structure. This interpretation predicts that the nucleus of this comet-like asteroid should be in rapid rotation. In November 2013, broadband photometry of P/2013 P5 was obtained with Lowell Observatory’s 4-meter Discovery Channel Telescope using the Large Monolithic Imager to investigate the possibility of rapid rotation. On chip optimal aperture photometry was performed on P/2013 P5. At an apparent magnitude V=22.5 magnitude, we found no significant variability in the light curve at the level of 0.15 magnitudes. General morphology changes in the nucleus-coma system of the asteroid were also investigated. We will present our analysis of this search for variability in both time and spatially across the coma relative to the object’s center of brightness. Hsieh, H. H., & Jewitt, D. 2006, Science, 312, 561Jewitt, D. 2012, AJ, 143, 66Jewitt, D.C., Agarwal, J., Weaver, H., Mutchler, M., & Larson, S. 2013, ApL, 778

Application of a Novel Long-Reach Manipulator Concept to Asteroid Redirect Missions

NASA Technical Reports Server (NTRS)

Dorsey, John T.; Doggett, William R.; Jones, Thomas C.; King, Bruce D.

2015-01-01

A high priority mission currently being formulated by NASA is to capture all or part of an asteroid and return it to cis-lunar space for examination by an astronaut crew. Two major mission architectures are currently being considered: in the first (Mission Concept A), a spacecraft would rendezvous and capture an entire free flying asteroid (up to 14 meters in diameter), and in the second (Mission Concept B), a spacecraft would rendezvous with a large asteroid (which could include one of the Martian moons) and retrieve a boulder (up to 4 meters in diameter). A critical element of the mission is the system that will capture the asteroid or boulder material, enclose it and secure it for the return flight. This paper describes the design concepts, concept of operations, structural sizing and masses of capture systems that are based on a new and novel Tendon- Actuated Lightweight In-Space MANipulator (TALISMAN) general-purpose robotic system. Features of the TALISMAN system are described and the status of its technology development is summarized. TALISMAN-based asteroid material retrieval system concepts and concepts-of-operations are defined for each asteroid mission architecture. The TALISMAN-based capture systems are shown to dramatically increase operational versatility while reducing mission risk. Total masses of TALISMAN-based systems are presented, reinforcing the mission viability of using a manipulator-based approach for the asteroid redirect mission.

77 FR 3102 - Procedures for Implementing the National Environmental Policy Act

Federal Register 2010, 2011, 2012, 2013, 2014

2012-01-23

... from solar system bodies (such as asteroids, comets, planets, dwarf planets, and planetary moons.../program which would return samples to Earth from solar system bodies (such as asteroids, comets, planets, dwarf planets, and planetary moons), which would likely receive a Restricted Earth Return categorization...

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.

Detection of ice and organics on an asteroidal surface.

PubMed

Rivkin, Andrew S; Emery, Joshua P

2010-04-29

Recent observations, including the discovery in typical asteroidal orbits of objects with cometary characteristics (main-belt comets, or MBCs), have blurred the line between comets and asteroids, although so far neither ice nor organic material has been detected on the surface of an asteroid or directly proven to be an asteroidal constituent. Here we report the spectroscopic detection of water ice and organic material on the asteroid 24 Themis, a detection that has been independently confirmed. 24 Themis belongs to the same dynamical family as three of the five known MBCs, and the presence of ice on 24 Themis is strong evidence that it also is present in the MBCs. We conclude that water ice is more common on asteroids than was previously thought and may be widespread in asteroidal interiors at much smaller heliocentric distances than was previously expected.

Asteroid/comet encounter opportunities for the Galileo VEEGA mission

NASA Technical Reports Server (NTRS)

Johannesen, Jennie R.; Nolan, Brian G.; Byrnes, Dennis V.; D'Amario, Louis A.

1988-01-01

The opportunity for the Galileo spacecraft to perform a close flyby of an asteroid or distant observation of a comet while on the Venus-Earth-Earth-Gravity-Assist (VEEGA) mission to Jupiter is discussed. More than 120 nominal trajectories were used in a scan program to identify asteroids passing within 30 million km of the spacecraft. A total of 47 asteroids were examined to determine the propellant cost of a close flyby. The possible flybys include a double asteroid flyby with No. 951 in October, 1991, with a flyby of No. 243 in August 1993. The factors considered in the selection of an asteroid include the propellant margin cost of modifying a nominal trajectory to include a close flyby, the size and type of asteroid, and the Jupiter arrival date.

Baffling system for the Wide Angle Camera (WAC) of ROSETTA mission

NASA Astrophysics Data System (ADS)

Brunello, Pierfrancesco; Peron, Fabio; Barbieri, Cesare; Fornasier, Sonia

2000-10-01

After the experience of GIOTTO fly-by to comet Halley in 1986, the European Space Agency planned to improve the scientific knowledge of these astronomical objects by means of an even more ambitious rendezvous mission with another comet (P/Wirtanen). This mission, named ROSETTA, will go on from 2003 to 2013, ending after the comet perihelion phase and including also the fly-by with two asteroids of the main belt (140 Siwa and 4979 Otawara). Scientific priority of the mission is the in situ investigation of the cometary nucleus, with the aim of better understanding the formation and the composition of planetesimals and their evolution over the last 4.5 billions of years. In this context, the Authors were involved in the design of the baffling for the Wide Angle Camera (WAC) of the imaging system (OSIRIS) carried on board of the spacecraft. Scientific requirements for the WAC are : a large field of view (FOV) of 12 degree(s) x 12 degree(s) with a resolution of 100 (mu) rad per pixel, UV response, and a contrast ratio of 10-4 in order to detect gaseous and dusty features close to the nucleus of the comet. TO achieve these performances, a fairly novel class of optical solutions employing off-axis sections of concentric mirrors was explored. Regarding baffling, the peculiar demand was the rejection of stray-light generated by the optics for sources within the FOV, since the optical entrance aperture is located at the level of the secondary mirror (instead of the primary as usual). This paper describes the baffle design and analyzes its performances, calculated by numerical simulation with ray tracing methods, at different angles of incidence of the light, for sources both outside and inside the field of view.

Physical Characterization of the Near-Earth Object Population

NASA Technical Reports Server (NTRS)

Binzel, Richard P.

2003-01-01

This program seeks to address the fundamental question: What are the relationships between asteroids, comets, and meteorites? To answer this question, we are studying the population of asteroids near the Earth which likely contain both asteroids and extinct comets and which is the immediate source for meteorites. An analysis of new and existing visible wavelength spectral data for more than 100 (Near-Earth Objects) NEOs, and Keck albedo data for more than 20 NEOs is underway. New asteroid-meteorite links are being found, the NEO population and hazard is being characterized, and the extinct comet component is being constrained. These results are contained within the following publication work during the current period: 1 book, 2 book chapters, 1 published paper, 2 papers submitted, 2 papers in preparation, 1 Ph. D. thesis in preparation, and 7 meeting abstracts/presentations.

The enigmatic object 2201 Oljato - Is it an asteroid or an evolved comet?

NASA Technical Reports Server (NTRS)

Mcfadden, Lucy A.; Cochran, Anita L.; Barker, Edwin S.; Cruikshank, Dale P.; Hartmann, William K.

1993-01-01

The orbital properties of near-earth object 2201 have been associated with meteor showers, and its modeled orbital evolution is chaotic - a property which might indicate a history related to comets. Telescopic observations of its visible and near-infrared spectral reflectance, broad-band visible and near-infrared photometry, infrared radiometric measurements, and radar echoes are reported here from two apparitions, 1979 and 1983. This asteroid has a high radiometric albedo, a property not associated with comet nuclei. In certain wavelength regimes it is classified as an S-type asteroid, in others, an E-type, but its overall spectral reflectance is not typical of either taxonomic type, and neither type is thought of as cometlike. Unexpectedly high ultraviolet reflectance at the 1979 apparition was suggested to be the result of residual outgassing as in a comet. The UV photometric data are modeled as fluorescent emission from neutral species found in comets. The resulting calculations indicate a plausible value for OH and CN emission at 0.3085 and 0.38 micron relative to the observed range of active comets.

Development and Testing of Harpoon-Based Approaches for Collecting Comet Samples

NASA Technical Reports Server (NTRS)

Purves, Lloyd (Compiler); Nuth, Joseph (Compiler); Amatucci, Edward (Compiler); Wegel, Donald; Smith, Walter; Church, Joseph; Leary, James; Kee, Lake; Hill, Stuart; Grebenstein, Markus;

Example Solar Electric Propulsion System asteroid tours using variational calculus

NASA Technical Reports Server (NTRS)

Burrows, R. R.

1985-01-01

Exploration of the asteroid belt with a vehicle utilizing a Solar Electric Propulsion System has been proposed in past studies. Some of those studies illustrated multiple asteroid rendezvous with trajectories obtained using approximate methods. Most of the inadequacies of those approximations are overcome in this paper, which uses the calculus of variations to calculate the trajectories and associated payloads of four asteroid tours. The modeling, equations, and solution techniques are discussed, followed by a presentation of the results.

Example Solar Electric Propulsion System asteroid tours using variational calculus

NASA Astrophysics Data System (ADS)

Burrows, R. R.

1985-06-01

Exploration of the asteroid belt with a vehicle utilizing a Solar Electric Propulsion System has been proposed in past studies. Some of those studies illustrated multiple asteroid rendezvous with trajectories obtained using approximate methods. Most of the inadequacies of those approximations are overcome in this paper, which uses the calculus of variations to calculate the trajectories and associated payloads of four asteroid tours. The modeling, equations, and solution techniques are discussed, followed by a presentation of the results.

Laboratory Studies of Cometary Materials - Continuity Between Asteroid and Comet

NASA Technical Reports Server (NTRS)

Messenger, Scott; Walker, Robert M.

2015-01-01

Laboratory analysis of cometary samples have been enabled by collection of cometary dust in the stratosphere by high altitude aircraft and by the direct sampling of the comet Wild-2 coma by the NASA Stardust spacecraft. Cometary materials are composed of a complex assemblage of highly primitive, unprocessed interstellar and primordial solar system materials as well as a variety of high temperature phases that must have condensed in the inner regions of the protoplanetary disk. These findings support and contradict conclusions of comet properties based solely on astronomical observations. These sample return missions have instead shown that there is a continuity of properties between comets and asteroids, where both types of materials show evidence for primitive and processed materials. Furthermore, these findings underscore the importance and value of direct sample return. There will be great value in comparing the findings of the Stardust cometary coma sample return mission with those of future asteroid surface sample returns OSIRIS-REx and Hayabusa II as well as future comet nucleus sample returns.

Asteroid Family Associations of Main-Belt Comets

NASA Astrophysics Data System (ADS)

Hsieh, Henry H.; Novakovic, Bojan; Kim, Yoonyoung; Brasser, Ramon

2016-10-01

We present a population-level analysis of the asteroid family associations of known main-belt comets or main-belt comet candidates (which, to date, have largely just been analyzed on individual bases as they have been discovered). In addition to family associations that have already been reported in the literature, we have identified dynamical relationships between 324P/La Sagra and the Alauda family, P/2015 X6 (PANSTARRS) and the Aeolia family, and P/2016 G1 (PANSTARRS) and the Adeona family. We will discuss the overall implications of these family associations, particularly as they pertain to the hypothesis that members of primitive asteroid family members may be more susceptible to producing observable sublimation-driven dust emission activity, and thus becoming main-belt comets. We will also discuss the significance of other dynamical and physical properties of a family or sub-family as they relate to the likelihood of that family containing one or more currently active main-belt comets.

On the relationship between gas and dust in 15 comets: an application to Comet 103P/Hartley 2 target of the NASA EPOXI mission of opportunity

NASA Astrophysics Data System (ADS)

Sanzovo, G. C.; Sanzovo, D. Trevisan; de Almeida, A. A.

After the success of Deep Impact mission to hit the nucleus of Comet 9P/Tempel 1 with an impactor, the concerns are turned now to the possible reutilization of this dormant flyby spacecraft in the study of another comet, for only about 10% of the cost of the original mission. Comet 103P/Hartley 2 on UT 2010 October 11 is the most attractive target in terms of available fuel at rendezvous and arrival time at the comet. In addition, the comet has a low inclination so that major orbital plane changes in the spacecraft trajectory are unnecessary. In an effort to provide information concerning the planning of this new NASA EPOXI space mission of opportunity, we use in this work, visual magnitudes measurements available from International Comet Quarterly (ICQ) to obtain, applying the Semi-Empirical Method of Visual Magnitudes - SEMVM (de Almeida, Singh, & Huebner 1997), the water production rates (in molecules/s) related to its perihelion passage of 1997. When associated to the water vaporization theory of Delsemme (1982), these rates allowed the acquisition of the minimum dimension for the effective nuclear radius of the comet. The water production rates were then converted into gas production rates (in g/s) so that, with the help of the strong correlation between gas and dust found for 12 periodic comets and 3 non-period comets (Trevisan Sanzovo 2006), we obtained the dust loss rates (in g/s), its behavior with the heliocentric distance and the dust-to-gas ratios in this physically attractive rendezvous target-comet to Deep Impact spacecraft at a closest approach of 700 km.

Mid-infrared spectra of comet nuclei

NASA Astrophysics Data System (ADS)

Kelley, Michael S. P.; Woodward, Charles E.; Gehrz, Robert D.; Reach, William T.; Harker, David E.

2017-03-01

Comet nuclei and D-type asteroids have several similarities at optical and near-IR wavelengths, including near-featureless red reflectance spectra, and low albedos. Mineral identifications based on these characteristics are fraught with degeneracies, although some general trends can be identified. In contrast, spectral emissivity features in the mid-infrared provide important compositional information that might not otherwise be achievable. Jovian Trojan D-type asteroids have emissivity features strikingly similar to comet comae, suggesting that they have the same compositions and that the surfaces of the Trojans are highly porous. However, a direct comparison between a comet and asteroid surface has not been possible due to the paucity of spectra of comet nuclei at mid-infrared wavelengths. We present 5-35 μm thermal emission spectra of comets 10P/Tempel 2, and 49P/Arend-Rigaux observed with the Infrared Spectrograph on the Spitzer Space Telescope. Our analysis reveals no evidence for a coma or tail at the time of observation, suggesting the spectra are dominated by the comet nucleus. We fit each spectrum with the near-Earth asteroid thermal model (NEATM) and find sizes in agreement with previous values. However, the NEATM beaming parameters of the nuclei, 0.74-0.83, are systematically lower than the Jupiter-family comet population mean of 1.03 ± 0.11, derived from 16- and 22-μm photometry. We suggest this may be either an artifact of the spectral reduction, or the consequence of an emissivity low near 16 μm. When the spectra are normalized by the NEATM model, a weak 10-μm silicate plateau is evident, with a shape similar to those seen in mid-infrared spectra of D-type asteroids. A silicate plateau is also evident in previously published Spitzer spectra of the nucleus of comet 9P/Tempel 1. We compare, in detail, these comet nucleus emission features to those seen in spectra of the Jovian Trojan D-types (624) Hektor, (911) Agamemnon, and (1172) Aneas, as well as those seen in the spectra of seven comet comae. The comet comae present silicate features with two distinct shapes, either trapezoidal, or more rounded, the latter apparently due to enhanced emission near 8 to 8.5 μm. The surfaces of Tempel 2, Arend-Rigaux, and Hektor best agree with the comae that present trapezoidal features, furthering the hypothesis that the surfaces of these targets must have high porosities in order to exhibit a spectrum similar to a comet coma. An emissivity minimum at 15 μm, present in the spectra of Tempel 2, Arend-Rigaux, Hektor, and Agamemnon, is also described, the origin of which remains unidentified. The compositional similarity between D-type asteroids and comets is discussed, and our data supports the hypothesis that they have similar origins in the early Solar System.

Linking main-belt comets to asteroid families

NASA Astrophysics Data System (ADS)

Novakovic, B.; Hsieh, H. H.; Cellino, A.

2012-09-01

Here we present our results obtained by applying different methods in order to establish a firm link between the main-belt comets (MBCs) and colisionally-formed asteroid families (AFs), i.e, to possibly find additional line of evidence supporting the hypothesis that MBCs may be preferentially found among the members of young AFs.

Spacecraft Mission Design for the Mitigation of the 2017 PDC Hypothetical Asteroid Threat

NASA Technical Reports Server (NTRS)

Barbee, Brent W.; Sarli, Bruno V.; Lyzhoft, Joshua; Chodas, Paul W.; Englander, Jacob A.

2017-01-01

This paper presents a detailed mission design analysis results for the 2017 Planetary Defense Conference (PDC) Hypothetical Asteroid Impact Scenario, documented at https://cneos.jpl.nasa.gov/ pd/cs/pdc17/. The mission design includes campaigns for both reconnaissance (flyby or rendezvous) of the asteroid (to characterize it and the nature of the threat it poses to Earth) and mitigation of the asteroid, via kinetic impactor deflection, nuclear explosive device (NED) deflection, or NED disruption. Relevant scenario parameters are varied to assess the sensitivity of the design outcome, such as asteroid bulk density, asteroid diameter, momentum enhancement factor, spacecraft launch vehicle, and mitigation system type. Different trajectory types are evaluated in the mission design process from purely ballistic to those involving optimal midcourse maneuvers, planetary gravity assists, and/or lowthrust solar electric propulsion. The trajectory optimization is targeted around peak deflection points that were found through a novel linear numerical technique method. The optimization process includes constrain parameters, such as Earth departure date, launch declination, spacecraft/asteroid relative velocity and solar phase angle, spacecraft dry mass, minimum/maximum spacecraft distances from Sun and Earth, and Earth/spacecraft communications line of sight. Results show that one of the best options for the 2017 PDC deflection is solar electric propelled rendezvous mission with a single spacecraft using NED for the deflection

PHYS: Division of Physical Chemistry 258 - Properties and Origins of Cometary and Asteroidal Organic Matter Delivered to the Early Earth

NASA Technical Reports Server (NTRS)

Messenger, Scott; Nguyen, Ann

2017-01-01

Comets and asteroids may have contributed much of the Earth's water and organic matter. The Earth accretes approximately 4x10(exp 7) Kg of dust and meteorites from these sources every year. The least altered meteorites contain complex assemblages of organic compounds and abundant hydrated minerals. These carbonaceous chondrite meteorites probably derive from asteroids that underwent hydrothermal processing within the first few million years after their accretion. Meteorite organics show isotopic and chemical signatures of low-T ion-molecule and grain-surface chemistry and photolysis of icy grains that occurred in cold molecular clouds and the outer protoplanetary disk. These signatures have been overprinted by aqueously mediated chemistry in asteroid parent bodies, forming amino acids and other prebiotic molecules. Comets are much richer in organic matter but it is less well characterized. Comet dust collected in the stratosphere shows larger H and N isotopic anomalies than most meteorites, suggesting better preservation of primordial organics. Rosetta studies of comet 67P coma dust find complex organic matter that may be related to the macromolecular material that dominates the organic inventory of primitive meteorites. The exogenous organic material accreting on Earth throughout its history is made up of thousands of molecular species formed in diverse processes ranging from circumstellar outflows to chemistry at near absolute zero in dark cloud cores and the formative environment within minor planets. NASA and JAXA are currently flying sample return missions to primitive, potentially organic-rich asteroids. The OSIRIS-REx and Hayabusa2 missions will map their target asteroids, Bennu and Ryugu, in detail and return regolith samples to Earth. Laboratory analyses of these pristine asteroid samples will provide unprecedented views of asteroidal organic matter relatively free of terrestrial contamination within well determined geological context. Studies of extraterrestrial materials and returned samples are essential to understand the origins of Solar System organic material and the roles of comets and asteroids to providing the starting materials for the emergence of life.

MEST-Do the ``rubble-pile'' asteroid-1950 DA, with low 1700 kg/m3 density, has a structure with spacetime center?

NASA Astrophysics Data System (ADS)

Cao, Dayong

2015-04-01

According to Einstein's equation and observation of flat universe, the paper gives new ideas both of dark massenergy and spacetime center, and supporses that some asteroids were comets which have spacetime center, and some comets were wraped up by rock in 2012. It explains of a observation about low density of the asteroid-1950 DA by spacetime center of the asteroid. (see Ben Rozitis, ``Cohesive forces prevent the rotational breakup of rubble-pile asteroid (29075) 1950 DA,'' http://www. nature.com / nature / journal / v512 / n7513/full/nature13632.html) It also can explain of a rock hull of 67P/Churyumov-Gerasimenko. (see Jonathan O'Callaghan, ``Comets are like deep fried ICE CREAM: Nasa ice-box experiment confirms 67P is hard on the outside but fluffy on the inside,'' http://www.dailymail.co.uk/sciencetech/article-2949020/Comets-like-deep-fried-ICE-CREAM-Nasa-ice-box-experiment-confirms-67P-hard-outside-fluffy-inside.html) (See Dayong Cao, ``MEST-The dark hole, dark comet and dark matter are the space-time center'' and ``MEST- avoid next extinction by a space-time effect'') http://meetings.aps.org/link/BAPS.2014.APR.L1.3 http://meetings.aps.org/link/BAPS.2014.APR.L1.2 http://meetings.aps.org/link/BAPS.2015.APR.L1.2 http://meeting.aps.org/Meeting/CAL12/Session/H1.8 http://meetings.aps.org/link/BAPS.2012.APR.K1.79

The Asteroid Impact Mission - Deflection Demonstration (AIM - D2)

NASA Astrophysics Data System (ADS)

Küppers, M.; Michel, P.; Carnelli, I.

2017-09-01

The Asteroid Impact Mission (AIM) is ESA's contribution to the international Asteroid Impact Deflection Assessment (AIDA) cooperation, targeting the demonstration of deflection of a hazardous near-earth asteroid. AIM will also be the first in-depth investigation of a binary asteroid and make measurements that are relevant for the preparation of asteroid resource utilisation. AIM is foreseen to rendezvous with the binary near-Earth asteroid (65803) Didymos and to observe the system before, during, and after the impact of NASA's Double Asteroid Redirection Test (DART) spacecraft. Here we describe the observations to be done by the simplified version Asteroid Impact Mission - Deflection Demonstration (AIM-D2) and show that most of the original AIM objectives can still be achieved.

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.

Challenges of Deflecting an Asteroid or Comet Nucleus with a Nuclear Burst

NASA Astrophysics Data System (ADS)

Bradley, P. A.; Plesko, C. S.; Clement, R. R. C.; Conlon, L. M.; Weaver, R. P.; Guzik, J. A.; Pritchett-Sheats, L. A.; Huebner, W. F.

2010-01-01

There are many natural disasters that humanity has to deal with over time. These include earthquakes, tsunamis, hurricanes, floods, asteroid strikes, and so on. Some of these disasters occur slowly enough that some advance warning is possible for affected areas. In this case, the response is to evacuate the affected area and deal with the damage later. The Katrina and Rita hurricane evacuations on the U.S. Gulf Coast in 2005 demonstrated the chaos that can result from such a response. In contrast with other natural disasters, it is likely that an asteroid or comet nucleus on a collision course with Earth will be detected with enough warning time to possibly deflect it away. Thanks to Near-Earth Object (NEO) surveys, people are working towards a goal of cataloging at least 90% of all near-Earth objects with diameters larger than ~140 meters in the next fifteen years. The important question then, is how to mitigate the threat from an asteroid or comet nucleus found to be on a collision course with Earth. In this paper, we briefly review some possible deflection methods, describe their good and bad points, and then embark on a more detailed description of using nuclear munitions in a standoff mode to deflect the asteroid or comet nucleus before it can hit Earth.

Hybrid Guidance Control for a Hypervelocity Small Size Asteroid Interceptor Vehicle

NASA Technical Reports Server (NTRS)

Zebenay, Melak M.; Lyzhoft, Joshua R.; Barbee, Brent W.

2017-01-01

Near-Earth Objects (NEOs) are comets and/or asteroids that have orbits in proximity with Earth's own orbit. NEOs have collided with the Earth in the past, which can be seen at such places as Chicxulub crater, Barringer crater, and Manson crater, and will continue in the future with potentially significant and devastating results. Fortunately such NEO collisions with Earth are infrequent, but can happen at any time. Therefore it is necessary to develop and validate techniques as well as technologies necessary to prevent them. One approach to mitigate future NEO impacts is the concept of high-speed interceptor. This concept is to alter the NEO's trajectory via momentum exchange by using kinetic impactors as well as nuclear penetration devices. The interceptor has to hit a target NEO at relative velocity which imparts a sufficient change in NEO velocity. NASA's Deep Impact mission has demonstrated this scenario by intercepting Comet Temple 1, 5 km in diameter, with an impact relative speed of approximately 10 km/s. This paper focuses on the development of hybrid guidance navigation and control (GNC) algorithms for precision hypervelocity intercept of small sized NEOs. The spacecraft's hypervelocity and the NEO's small size are critical challenges for a successful mission as the NEO will not fill the field of view until a few seconds before intercept. The investigation needs to consider the error sources modeled in the navigation simulation such as spacecraft initial state uncertainties in position and velocity. Furthermore, the paper presents three selected spacecraft guidance algorithms for asteroid intercept and rendezvous missions. The selected algorithms are classical Proportional Navigation (PN) based guidance that use a first order difference to compute the derivatives, Three Plane Proportional Navigation (TPPN), and the Kinematic Impulse (KI). A manipulated Bennu orbit that has been changed to impact Earth will be used as a demonstrative example to compare the three methods. In addition, a hybrid approach that is a combination between proportional navigation and kinematic impulse will be investigated to find an effective, error tolerant, and power saving approach. A 3-dimension mission scenario for both the asteroid and the interceptor spacecraft software simulator is developed for testing of the controllers. The current result demonstrates that a miss distance magnitude of less than 10m is found using the PN and TPPN guidance laws for small asteroid in the presence of error in the spacecraft states. Moreover, the paper presents these results and also the hybrid control approach simulation results.

The σ-Capricornids complex of near-Earth objects

NASA Astrophysics Data System (ADS)

Babadzhanov, P. B.; Kokhirova, G. I.; Khamroev, U. Kh.

2015-04-01

The Earth-crossing asteroids 2008BO16, 2011EC41, and 2013CT36 have very similar orbits according to the Southworth and Hawkins DSH criterion. Their orbits are additionally classified as comet-like based on using the Tisserand parameter which is a standard tool used to distinction between asteroids and comets. The orbital evolution research shows that they cross the Earth's orbit four times over one cycle of the perihelion argument variations. Consequently, a meteoroid stream, possibly associated with them, may produce four meteor showers. Theoretic parameters of the predicted showers were calculated and identified with the observable nighttime σ-Capricornids and χ-Sagittariids, and daytime χ-Capricornids and Capricornids-Sagittariids meteor showers. The similar comet-like orbits and the linkage with the same meteoroid stream producing four active showers provide strong evidence that these asteroids have a common cometary origin. Earlier, it was demonstrated that the Earth-crossing asteroids (2101) Adonis and 1995CS, being a potentially hazardous asteroid (PHA), were recognized as dormant comets because of their linkage with the σ-Capricornids meteoroid stream. Thus, a conclusion was made, that either the considered objects are large pieces of the Adonis, or all five objects are extinct or dormant fragments of a larger comet that was the parent body of the σ-Capricornids meteoroid stream, and whose break-up occurred several tens of thousands years ago. During 2010-2011, three σ-Capricornids fireballs were captured by the Tajikistan fireball network. Taking into account the observations in Canada and the USA, the dynamic and physical properties of the σ-Capricornid meteoroids were identified. According to the estimated meteoroids bulk density a non-homogeneous compound of the σ-Capricornids shower comet-progenitor was suggested.

A Spitzer Search for Activity in Dormant Comets

NASA Astrophysics Data System (ADS)

Mommert, Michael; Trilling, David; Hora, Joseph; Smith, Howard

2018-05-01

Dormant comets are inactive cometary nuclei hiding in the asteroid populations. Due to their cometary origin, it is possible that volatiles are still retained in their interiors. This hypothesis is supported by the case of near-Earth asteroid Don Quixote, which had been known as an asteroid for 30 yr before activity was discovered in this team's prior Spitzer observations. Interestingly, Don Quixote showed outgassing of CO or CO2, but no dust activity. This significant observation was repeated in 2017 with the same result, suggesting that Don Quixote is continuously outgassing - and still an active comet. Don Quixote's case suggests that other dormant comets might be outgassing with low dust production rates, concealing their activity to optical surveys. The implication of this scenario is that the volatile inventory of the asteroid populations might be significantly larger than currently assumed. We propose 48.8 hr of deep IRAC observations of eight dormant comets in search of faint activity in them. For each target, we will (1) measure (or provide upper limits on) gas and dust production rates from our IRAC CH1 and CH2 observations, (2) derive the diameters and albedos of five of our targets using asteroid thermal modeling, (3) measure the near-infrared spectral slope between CH1 and CH2 for three of our targets, and (4) obtain lightcurve observations of the nuclei of all of our targets. Our observations, which are combined with ground-based observations as part of a NASA-funded program, will provide important constraints on the volatile content of the asteroid population, as well as the origin, evolution, and physical properties of cometary nuclei.

Evidence of Collisional Histories of Asteroids, Comets and Meteorites: Comparisons with Shocked Minerals

NASA Technical Reports Server (NTRS)

Lederer, Susan M.; Jensen, Elizabeth; Smith, Douglas; Fane, Michael; Whizin, Akbar; Landsman, Zoe A.; Wooden, Diane H.; Lindsay, Sean S.; Cintala, Mark; Keller, Lindsay P.;

Using Information from Rendezvous Missions For Best-Case Appraisals of Impact Damage to Planet Earth Caused By Natural Objects

NASA Technical Reports Server (NTRS)

Arnold, J. O.; Chodas, P. W.; Ulamec, S.; Mathias, D. L.; Burkhard, C. D.

2017-01-01

The Asteroid Threat Assessment Project (ATAP), a part of NASAs Planetary Defense Coordination Office (PDCO) has the responsibility to appraise the range of surface damage by potential asteroid impacts on land or water. If a threat is realized, the project will provide appraisals to officials empowered to make decisions on potential mitigation actions. This paper describes a scenario for assessment of surface damage when characterization of an asteroid had been accomplished by a rendezvous mission that would be conducted by the international planetary defense community. It is shown that the combination of data from ground and in-situ measurements on an asteroid provides knowledge that can be used to pin-point its impact location and predict the level of devastation it would cause. The hypothetical asteroid 2017 PDC with a size of 160 to 290 m in diameter to be discussed at the PDC 2017 meeting is used as an example. In order of importance for appraising potential damage, information required is: (1) where will the surface impact occur? (2) What is the mass, shape and size of the asteroid and what is its entry state (speed and entry angle) at the 100 km atmospheric pierce point? And (3) is the asteroid a monolith or a rubble pile? If it is a rubble pile, what is its sub and interior structure? Item (1) is of first order importance to determine levels of devastation (loss of life and infrastructure damage) because it varies strongly on the impact location. Items (2) and (3) are used as input for ATAPs simulations to define the level of surface hazards: winds, overpressure, thermal exposure; all created by the deposition of energy during the objects atmospheric flight, andor cratering. Topics presented in this paper include: (i) The devastation predicted by 2017 PDCs impact based on initial observations using ATAPs risk assessment capability, (ii) How information corresponding to items (1) to (3) could be obtained from a rendezvous mission, and (iii) How information from a rendezvous mission could be used, along with that from ground observations and data from the literature, could provide input for an new risk analysis capability that is emerging from ATAPs research. It is concluded that this approach would result in appraisal with the least uncertainty possible (herein called the best-case) using simulation capabilities that are currently available or will be in the future.

Using Information from Rendezvous Missions For Best-Case Appraisals of Impact Damage to Planet Earth Caused By Natural Objects

NASA Technical Reports Server (NTRS)

Arnold, James O.; Chodas, Paul W.; Ulamec, Stephan; Mathias, Donovan L.; Burkhard, Craig D.

2017-01-01

The Asteroid Threat Assessment Project (ATAP), a part of NASAs Planetary Defense Coordination Office (PDCO) has the responsibility to appraise the range of surface damage by potential asteroid impacts on land or water. If a threat is realized, the project will provide appraisals to officials empowered to make decisions on potential mitigation actions. This paper describes a scenario for assessment of surface damage when characterization of an asteroid had been accomplished by a rendezvous mission that would be conducted by the international planetary defense community. It is shown that the combination of data from ground and in-situ measurements on an asteroid provides knowledge that can be used to pin-point its impact location and predict the level of devastation it would cause. The hypothetical asteroid 2017 PDC with a size of 160 to 290 m in diameter to be discussed at the PDC 2017 meeting is used as an example. In order of importance for appraising potential damage, information required is: (1) where will the surface impact occur? (2) What is the mass, shape and size of the asteroid and what is its entry state (speed and entry angle) at the 100 km atmospheric pierce point? And (3) is the asteroid a monolith or a rubble pile? If it is a rubble pile, what is its sub and interior structure? Item (1) is of first order importance to determine levels of devastation (loss of life and infrastructure damage) because it varies strongly on the impact location. Items (2) and (3) are used as input for ATAPs simulations to define the level of surface hazards: winds, overpressure, thermal exposure; all created by the deposition of energy during the objects atmospheric flight, and/or cratering. Topics presented in this paper include: (i) The devastation predicted by 2017 PDCs impact based on initial observations using ATAPs risk assessment capability, (ii) How information corresponding to items (1) to (3) could be obtained from a rendezvous mission, and (iii) How information from a rendezvous mission could be used, along with that from ground observations and data from the literature, could provide input for an new risk analysis capability that is emerging from ATAPs research. It is concluded that this approach would result in appraisal with the least uncertainty possible (herein called the best-case) using simulation capabilities that are currently available or will be in the future.

Using Information from Rendezvous Missions for Best-Case Appraisals of Impact Damage to Planet Earth Caused by Natural Objects

NASA Technical Reports Server (NTRS)

Arnold, James O.; Chodas, Paul W.; Ulamec, Stephan; Mathias, Donovan L.; Burkhard, Craig D.

2017-01-01

The Asteroid Threat Assessment Project (ATAP), a part of NASAs Planetary Defense Coordination Office (PDCO) has the responsibility to appraise the range of surface damage by potential asteroid impacts on land or water. If a threat is realized, the project will provide appraisals to officials empowered to make decisions about potential mitigation actions. This paper describes a scenario for assessment of surface damage when characterization of an asteroid had been accomplished by a rendezvous mission that would be conducted by the international planetary defense community. It is shown that the combination of data from ground and in-situ measurements on an asteroid provides knowledge that can be used to pin-point its impact location and predict the level of devastation it would cause. The hypothetical asteroid 2017 PDC with a size range of 160 to 290 m in diameter to be discussed at the PDC 2017 is used as an example. In order of importance for appraising potential damage, information required is: (1) where will the surface impact occur? (2) what is the mass, shape and size of the asteroid and what is its entry state (speed and entry angle) at the 100 km atmospheric pierce point? And (3) is the asteroid a monolith or a rubble pile? If it is a rubble pile, what is its structure and heterogeneity from the surface and throughout its interior? Item (1) is of first order importance to determine levels of devastation (loss of life and infrastructure damage) because it varies strongly on the impact location. Items (2) and (3) are used as inputs for ATAPs simulations to define the level of surface hazards: winds, overpressure, thermal exposure; all created by the deposition of energy during the objects atmospheric flight, andor cratering. Topics presented in this paper include: (i) the devastation predicted by 2017 PDCs impact on land based on initial observations using ATAPs risk assessment capability, (ii) how information corresponding to items (1) to (3) could be obtained from a rendezvous mission, and (iii) how information from a rendezvous mission could be used, along with that from ground observations and data from the literature to provide input for a new risk analysis capability that is emerging from ATAPs research. It is concluded that this approach would result in the creation of an appraisal of the threat from 2017 PDC with the least uncertainty possible, herein called the best-case.

Compressed/reconstructed test images for CRAF/Cassini

NASA Technical Reports Server (NTRS)

Dolinar, S.; Cheung, K.-M.; Onyszchuk, I.; Pollara, F.; Arnold, S.

1991-01-01

A set of compressed, then reconstructed, test images submitted to the Comet Rendezvous Asteroid Flyby (CRAF)/Cassini project is presented as part of its evaluation of near lossless high compression algorithms for representing image data. A total of seven test image files were provided by the project. The seven test images were compressed, then reconstructed with high quality (root mean square error of approximately one or two gray levels on an 8 bit gray scale), using discrete cosine transforms or Hadamard transforms and efficient entropy coders. The resulting compression ratios varied from about 2:1 to about 10:1, depending on the activity or randomness in the source image. This was accomplished without any special effort to optimize the quantizer or to introduce special postprocessing to filter the reconstruction errors. A more complete set of measurements, showing the relative performance of the compression algorithms over a wide range of compression ratios and reconstruction errors, shows that additional compression is possible at a small sacrifice in fidelity.

Design concepts and performance of NASA X-band (7162 MHz/8415 MHz) transponder for deep-space spacecraft applications

NASA Technical Reports Server (NTRS)

Mysoor, N. R.; Perret, J. D.; Kermode, A. W.

1991-01-01

The design concepts and measured performance characteristics are summarized of an X band (7162 MHz/8415 MHz) breadboard deep space transponder (DSP) for future spacecraft applications, with the first use scheduled for the Comet Rendezvous Asteroid Flyby (CRAF) and Cassini missions in 1995 and 1996, respectively. The DST consists of a double conversion, superheterodyne, automatic phase tracking receiver, and an X band (8415 MHz) exciter to drive redundant downlink power amplifiers. The receiver acquires and coherently phase tracks the modulated or unmodulated X band (7162 MHz) uplink carrier signal. The exciter phase modulates the X band (8415 MHz) downlink signal with composite telemetry and ranging signals. The receiver measured tracking threshold, automatic gain control, static phase error, and phase jitter characteristics of the breadboard DST are in good agreement with the expected performance. The measured results show a receiver tracking threshold of -158 dBm and a dynamic signal range of 88 dB.

Asteroids, comets, meteors, and their interrelations. Part II: Editorial review

NASA Astrophysics Data System (ADS)

Muinonen, Karri; Granvik, Mikael; Penttilä, Antti; Gritsevich, Maria

2016-04-01

The Asteroids, Comets, Meteors 2014 (ACM 2014) conference was organized in Helsinki in June 30-July 4, 2014, with the first collection of the peer-reviewed papers published in December 2015 in the Special Issue of Planetary and Space Science (Muinonen et al., 2015). The present issue contains the second collection of papers from ACM 2014.

Imaging the interiors of near-earth objects with radio reflection tomography

NASA Technical Reports Server (NTRS)

Safaeinili, A.; Ostro, S. J.

2002-01-01

Scenarios for mitigation of asteroid comet collisions include the use of explosives to deflect or destroythe projectile. However, as demonstrated by Asphaug et al.( 1998), the outcome of explosive energy transfer to an asteroid or comet (via a bomb or a hypervelocity impact) is extremely sensitive to the pre-existing configuration of fractures and voids.

The Near-Earth Space Surveillance (NESS) Mission: Discovery, Tracking, and Characterization of Asteroids, Comets, and Artificial Satellites with a Microsatellite

NASA Technical Reports Server (NTRS)

Hildebrand, A. R.; Carroll, K. A.; Balam, D. D.; Cardinal, R. D.; Matthews, J. M.; Kuschnig, R.; Walker, G. A. H.; Brown, P. G.; Tedesco, E. F.; Worden, S. P.

2001-01-01

The Near-Earth Space Surveillance (NESS) Mission, a microsatellite dedicated to observing near-Earth (NEO) and interior-to-the-Earth (IEO)asteroids and comets plus artificial satellites, is currently being studied under contract to the Canadian Space Agency. Additional information is contained in the original extended abstract.

The 1986 DA and 1986 EB: M-class asteroids in near-Earth orbits

NASA Technical Reports Server (NTRS)

Gradie, Jonathan; Tedesco, Edward

1987-01-01

The Earth-approaching asteroid population is composed of asteroids in orbits with short lifetimes compared with the age of the solar system. These objects which are comprised of Aten, Apollo, and Amor asteroids must be replenished from either cometary or mainbelt asteroid sources since lifetimes against collision with or ejection by a planet are on the order of 10 to 100 million years. The physical study of Earth-approaching asteroids is constrained by the generally long period between favorable apparitions and poorly known orbits. Broadband spectrophotometry on the Johnson UBVR system and the Eight-Color Asteroid Survey system were obtained at Kitt Peak National Observatory and on the Johnson JHK system and at 10 and 20 microns at the NASA Infrared Telescope Facility at Mauna Kea Observatory. These observations were used to determine the absolute visual magnitudes and to derive the visual geometric albedos and diameters on the IRAS system. The spectral reflectance properties and geometric albedos of the M-class asteroids are consistent compositions analogous to the iron nickel meteorites or the enstatite-metal assemblages of the enstatite chondrites. The issue of the source(s) of the near-Earth asteroids population was examined by comparing the classifications on the scheme employed by Gradie and Tedesco of 38 such asteroids. Most of the near-Earth objects is indeed the asteroid belt as the observations suggest, then a method for removing extinct nuclei of short period comets must be found since the rate of production of short period comets from the long period comets is relatively large.

Castalia: A European Mission to a Main Belt Comet

NASA Astrophysics Data System (ADS)

Snodgrass, Colin; Castalia mission science Team

2013-10-01

Main Belt Comets (MBCs) are a newly identified population, with stable asteroid-like orbits in the outer main belt and a comet-like appearance. It is believed that they survived the age of the solar system in a dormant state and that their activity occurred only recently. Water ice is the only volatile expected to survive, and only when buried under an insulating surface. Excavation by impact could bring the water ice (closer) to the surface and trigger the start of MBC activity. The specific science goals of the Castalia mission are: 1. Characterize a new Solar System family, the MBCs, by in-situ investigation 2. Understand the physics of activity on MBCs 3. Directly detect water in the asteroid belt 4. Test if MBCs are a viable source for Earth’s water 5. Use MBCs as tracers of planetary system formation and evolution These goals can be achieved by a spacecraft designed to rendezvous with and orbit an MBC for some months, arriving before the active period begins for mapping before directly sampling the gas and dust released during the active phase. Given the low level of activity of MBCs, and the expectation that their activity comes from only a localized patch on the surface, the orbiting spacecraft will have to be able to maintain a very close orbit over extended periods - the Castalia plan envisages an orbiter capable of ‘hovering’ autonomously at distances of only a few km from the surface of the MBC. The straw-man instrument payload is made up of: - Visible and near-infrared spectral imager - Thermal infrared imager - Radio science - Dust impact detector - Dust composition analyzer - Neutral/ion mass spectrometer - Magnetometer - Plasma package In addition to this, the option of a surface science package is being considered. At the moment MBC 133P/Elst-Pizarro is the best-known target for such a mission. A design study for the Castalia mission has been carried out in partnership between the science team, DLR and OHB Systems. This study looked at possible missions to 133P with launch dates around 2025, and found that this (and other MBC targets as backups) are reachable with an ESA M-class type mission.

Castalia - European Mission to a Main Belt Comet

NASA Astrophysics Data System (ADS)

Hilchenbach, M.

2013-12-01

Main Belt Comets (MBCs) are a recently identified new solar system population with stable asteroid-like orbits and a comet-like appearance. It is believed that they survived the age of the solar system in a dormant state and that their activity occurred only recently. Buried water ice is the only volatile expected to survive under an insulating surface. Excavation by an impact might expose the ice and trigger the start of MBC activity. The specific science goals of the Castalia mission are: 1. Characterize a new Solar System family, the MBCs, by in-situ investigation 2. Understand the physics of activity on MBCs 3. Directly detect water in the asteroid belt 4. Test if MBCs are a viable source for Earth's water 5. Use MBCs as tracers of planetary system formation and evolution These goals can be achieved by a spacecraft designed to rendezvous with and orbit an MBC for a time interval of some months, arriving before the active period for mapping and then directly sampling the gas and dust released during the active phase. Given the low level of activity of MBCs, and the expectation that their activity comes from only a localized patch on the surface, the orbiting spacecraft will have to be able to maintain a very close orbit over extended periods - the Castalia plan envisages an orbiter capable of ';hovering' autonomously at distances of only a few km from the surface of the MBC. The straw-man instrument payload is made up of: - Visible and near-infrared spectral imager - Thermal infrared imager - Radio science - Dust impact detector - Dust composition analyzer - Neutral/ion mass spectrometer - Magnetometer - Plasma package In addition to this, the option of a surface science package is being considered. At the moment MBC 133P/Elst-Pizarro is the best-known target for such a mission. A design study for the Castalia mission has been carried out in partnership between the science team, DLR and OHB Systems. This study looked at possible missions to 133P with launch dates around 2025, and found that this (and other MBC targets as backups) are reachable within an ESA M-class type mission.

Low-Cost Innovation in Spaceflight: The Near Earth Asteroid Rendezvous (NEAR) Shoemaker Mission

NASA Technical Reports Server (NTRS)

McCurdy, Howard E.

2005-01-01

On a spring day in 1996, at their research center in the Maryland countryside, representatives from the Johns Hopkins University Applied Physics Laboratory (APL) presented Administrator Daniel S. Goldin of the National Aeronautics and Space Administration (NASA) with a check for $3.6 million. 1 Two and a half years earlier, APL officials had agreed to develop a spacecraft capable of conducting an asteroid rendezvous and to do so for slightly more than $122 million. This was a remarkably low sum for a spacecraft due to conduct a planetaryclass mission. By contrast, the Mars Observer spacecraft launched in 1992 for an orbital rendezvous with the red planet had cost $479 million to develop, while the upcoming Cassini mission to Saturn required a spacecraft whose total cost was approaching $1.4 billion. In an Agency accustomed to cost overruns on major missions, the promise to build a planetary-class spacecraft for about $100 million seemed excessively optimistic.

Understanding the Effects of Collisional Evolution and Spacecraft Impact Experiments on Comets and Asteroids

NASA Technical Reports Server (NTRS)

Lederer, S.M.; Jensen, E.A.; Fane, M.; Smith, D.C.; Holmes, J.; Keller, L.P.; Lindsay, S.S.; Wooden, D.H.; Whizin, A.; Cintala, M.J.;

Two Years of NEOWISE Asteroid Data

NASA Image and Video Library

2016-04-04

NASA's asteroid hunting NEOWISE survey uses infrared to detect and characterize asteroids and comets. Since the mission was restarted in December 2013, NEOWISE has discovered 72 near-Earth objects and characterized 439 others.

The Origin of Apollo Objects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perlmutter, Saul

1984-03-29

The source of the Earth-orbit-crossing asteroids has been much debated. (This class of asteroidal bodies includes the Apollo, Aten, and some Amor objects, each with its own orbital characteristics; we shall use the term Apollo objects to mean all Earth-crossers.) It is difficult to find a mechanism which would create new Apollo objects at a sufficient rate to balance the loss due to collision with planets and ejection from the solar system, and thus explain the estimated steady-state number. A likely source is the main asteroid belt, since it has similar photometric characteristics. There are gaps in the main beltmore » which correspond to orbits resonant with the orbits of Jupiter and Saturn, and it has been shown that the resonances can perturb a body into an Earth-crossing orbit. Apollo objects could thus be generated when random collisions between asteroids in the main belt sent fragments into these resonant orbits. Calculations of the creation rate from these random collisions, however, yielcl numbers too low by a factor of four. This rate could be significantly lower given the uncertainty in the efficiency of the resonance mechanism. As an alternative, it was suggested that the evaporation of a comet's volatile mantle as it passes near the sun could provide enough non-gravitational force to move the comet into an orbit with aphelion inside of Jupiter's orbit, and thus safe from ejection from the solar system. The probability of such an event occurring is unknown, although the recent discovery of the 'asteroid' 1983 TB, with an orbit matching that of the Geminid meteor shower, suggests that such a mechanism has occurred at least once. New evidence from paleontology and geophysics, however, suggests a better solution to the problem of the source of the Apollos. M. Davis, P. Hut, and R. A. Muller recently proposed that an unseen companion to the sun passes through the Oort cloud every 28 million years, sending a shower of comets to the Earth; this provides an explanation for the periodicity of the fossil record of extinctions found by D. M. Raup and J. J. Sepkoski. W. Alvarez and R. A. Muller have shown that the craters on the earth have an age distribution with a periodicity and phase consistent with this hypothesis. These periodic comet showers would of course pass through the entire solar system, colliding with other bodies besides the earth. When the target is the asteroid belt, many small comets will have sufficient kinetic energy to disrupt large asteroids. This will generate many more fragments in the resonant orbits than would be generated by random collisions of asteroids with each other, and hence more Apollo objects. In this report, we shall calculate approximately (A) the number of comets per shower which cross the asteroid belt, (B) the probability of collisions with a single asteroid per shower, (C) the number of fragments with radius > 0.5 km which reach Apollo orbits, and (D) the current expected number of Apollos derived from comet/asteroid collisions. Given conservative assumptions, the calculated number is in agreement with observations.« less

Low-thrust mission risk analysis, with application to a 1980 rendezvous with the comet Encke

NASA Technical Reports Server (NTRS)

Yen, C. L.; Smith, D. B.

1973-01-01

A computerized failure process simulation procedure is used to evaluate the risk in a solar electric space mission. The procedure uses currently available thrust-subsystem reliability data and performs approximate simulations of the thrust sybsystem burn operation, the system failure processes, and the retargeting operations. The method is applied to assess the risks in carrying out a 1980 rendezvous mission to the comet Encke. Analysis of the results and evaluation of the effects of various risk factors on the mission show that system component failure rates are the limiting factors in attaining a high mission relability. It is also shown that a well-designed trajectory and system operation mode can be used effectively to partially compensate for unreliable thruster performance.

Evidence of Collisional Histories of Asteroids, Comets and Meteorites: Comparisons with Shocked Minerals

NASA Astrophysics Data System (ADS)

Lederer, Susan M.; Jensen, Elizabeth; Smith, Douglas; Fane, Michael; Whizin, Akbar; Landsman, Zoe A.; Wooden, Diane H.; Lindsay, Sean S.; Cintala, Mark; Keller, Lindsay P.; Zolensky, Michael

2017-10-01

Evidence of the collisional history of comets and asteroids has been emerging from analyses of cometary forsterite and enstatite returned from Comet Wild 2 by the Stardust mission (Keller et al.Geochim. Cosmochim. Acta 72, 2008; Tomeoka et al. MAPS 43, 2008; Jacobs et al. MAPS 44, 2009). Likewise, shock metamorphism is observed in many meteoritic forsterites and enstatites (McCausland et al. AGU, 2010), suggesting similar collisional histories for asteroids. Further exploration of the effects of collisions is slated for the upcoming Asteroid Impact Mission/Double Asteroid Redirection Test (AIM/DART) mission, expected for launch in 2020. DART will impact Didymoon, the companion of the larger 65803 Didymos (1996 G2) asteroid, and AIM will use its instrumentation to characterize the impact.A suite of relevant impact experiments have been carried out in the Experimental Impact Laboratory at the NASA Johnson Space Center at velocities ranging from ~2.0 - 2.8 km s-1 and temperatures from 25°C to -100°C. Targets include a suite of minerals typically found in cometary dust and in asteroids and meteorites: Mg-rich forsterite (olivine), enstatite (orthopyroxene), diopside (clinopyroxene), magnesite (Mg-rich carbonate), and serpentine (phyllosilicate). Transmission Electron Microscope (TEM) imaging indicates evidence of shock similar to that seen in forsterite and enstatite from Comet Wild 2. Fourier Transform Infrared (FTIR) Spectroscopy will also be used for comparisons with meteorite spectra. A quantitative analysis of the shock pressures required to induce planar dislocations and spectral effects with respect to wavelength will also be presented.Funding provided by the NASA PG&G grant 09-PGG09-0115, NSF grant AST-1010012. Special thanks to NASA EIL staff, F. Cardenas and R. Montes.

Spacewatch Survey of the Solar System

NASA Technical Reports Server (NTRS)

McMillan, Robert S.

2000-01-01

The purpose of the Spacewatch project is to explore the various populations of small objects throughout the solar system. Statistics on all classes of small bodies are needed to infer their physical and dynamical evolution. More Earth Approachers need to be found to assess the impact hazard. (We have adopted the term "Earth Approacher", EA, to include all those asteroids, nuclei of extinct short period comets, and short period comets that can approach close to Earth. The adjective "near" carries potential confusion, as we have found in communicating with the media, that the objects are always near Earth, following it like a cloud.) Persistent and voluminous accumulation of astrometry of incidentally observed main belt asteroids MBAs will eventually permit the Minor Planet Center (MPQ to determine the orbits of large numbers (tens of thousands) of asteroids. Such a large body of information will ultimately allow better resolution of orbit classes and the determinations of luminosity functions of the various classes, Comet and asteroid recoveries are essential services to planetary astronomy. Statistics of objects in the outer solar system (Centaurs, scattered-disk objects, and Trans-Neptunian Objects; TNOs) ultimately will tell part of the story of solar system evolution. Spacewatch led the development of sky surveying by electronic means and has acted as a responsible interface to the media and general public on this discipline and on the issue of the hazard from impacts by asteroids and comets.

Comet nucleus and asteroid sample return missions

NASA Technical Reports Server (NTRS)

1992-01-01

Three Advanced Design Projects have been completed this academic year at Penn State. At the beginning of the fall semester the students were organized into eight groups and given their choice of either a comet nucleus or an asteroid sample return mission. Once a mission had been chosen, the students developed conceptual designs. These were evaluated at the end of the fall semester and combined into three separate mission plans, including a comet nucleus same return (CNSR), a single asteroid sample return (SASR), and a multiple asteroid sample return (MASR). To facilitate the work required for each mission, the class was reorganized in the spring semester by combining groups to form three mission teams. An integration team consisting of two members from each group was formed for each mission so that communication and information exchange would be easier among the groups. The types of projects designed by the students evolved from numerous discussions with Penn State faculty and mission planners at the Johnson Space Center Human/Robotic Spacecraft Office. Robotic sample return missions are widely considered valuable precursors to manned missions in that they can provide details about a site's environment and scientific value. For example, a sample return from an asteroid might reveal valuable resources that, once mined, could be utilized for propulsion. These missions are also more adaptable when considering the risk to humans visiting unknown and potentially dangerous locations, such as a comet nucleus.

The Spaceguard Survey: Report of the NASA International Near-Earth-Object Detection Workshop

NASA Technical Reports Server (NTRS)

Morrison, David (Editor)

1992-01-01

Impacts by Earth-approaching asteroids and comets pose a significant hazard to life and property. Although the annual probability of the Earth being struck by a large asteroid or comet is extremely small, the consequences of such a collision are so catastrophic that it is prudent to assess the nature of the threat and to prepare to deal with it. The first step in any program for the prevention or mitigation of impact catastrophes must involve a comprehensive search for Earth-crossing asteroids and comets and a detailed analysis of their orbits. At the request of the U.S. Congress, NASA has carried out a preliminary study to define a program for dramatically increasing the detection rate of Earth-crossing objects, as documented in this workshop report.

OSIRIS-REx Orbit Determination Covariance Studies at Bennu

NASA Technical Reports Server (NTRS)

Antreasian, P. G.; Moreau, M.; Jackman, C.; Williams, K.; Page, B.; Leonard, J. M.

2016-01-01

The Origins Spectral Interpretation Resource Identification Security Regolith Explorer (OSIRIS-REx) mission is a NASA New Frontiers mission launching in 2016 to rendezvous with the small, Earth-crossing asteroid (101955) Bennu in late 2018, and ultimately return a sample of regolith to Earth. Approximately 3 months before the encounter with Bennu, the asteroid finally becomes detectable in the narrow field PolyCam imager. The spacecraft's rendezvous with Bennu begins with a series of four Asteroid Approach Maneuvers, which slow the spacecraft's speed relative to Bennu beginning two and a half months prior to closest approach, ultimately delivering the spacecraft to a point 18 km from Bennu on Nov 18, 2018. An extensive campaign of proximity operations activities to characterize the properties of Bennu and select a suitable sample site will follow. This paper will discuss the challenges of navigating near a small 500-m diameter asteroid. The navigation at close proximity is dependent on the accurate mathematical model or digital terrain map of the asteroids shape. Predictions of the spacecraft state are very sensitive to spacecraft small forces, solar radiation pressure, and mis-modeling of Bennu's gravity field. Uncertainties in the physical parameters of the central body Bennu create additional challenges. The navigation errors are discussed and their impact on science planning will be presented.

OSIRIS-REx Orbit Determination Covariance Studies at Bennu

NASA Technical Reports Server (NTRS)

Antreasian, P. G.; Moreau, M.; Jackman, C.; Williams, K.; Page, B.; Leonard, J. M.

2016-01-01

The Origins Spectral Interpretation Resource Identification Security Regolith Explorer (OSIRIS-REx) mission is a NASA New Frontiers mission launching in 2016 to rendezvous with the small, Earth-crossing asteroid (101955) Bennu in late 2018, ultimately returning a sample of regolith to Earth. Approximately three months before the encounter with Bennu, the asteroid becomes detectable in the narrow field PolyCam imager. The spacecraft's rendezvous with Bennu begins with a series of four Asteroid Approach Maneuvers, slowing the spacecraft's speed relative to Bennu beginning two and a half months prior to closest approach, ultimately delivering the spacecraft to a point 18 km from Bennu in Nov, 2018. An extensive campaign of proximity operations activities to characterize the properties of Bennu and select a suitable sample site will follow. This paper will discuss the challenges of navigating near a small 500-m diameter asteroid. The navigation at close proximity is dependent on the accurate mathematical model or digital terrain map of the asteroid's shape. Predictions of the spacecraft state are very sensitive to spacecraft small forces, solar radiation pressure, and mis-modeling of Bennu's gravity field. Uncertainties in the physical parameters of the central body Bennu create additional challenges. The navigation errors are discussed and their impact on science planning will be presented.

Are There Many Inactive Jupiter-Family Comets among the Near-Earth Asteroid Population?

NASA Astrophysics Data System (ADS)

Fernández, Julio A.; Gallardo, Tabaré; Brunini, Adrián

2002-10-01

We analyze the dynamical evolution of Jupiter-family (JF) comets and near-Earth asteroids (NEAs) with aphelion distances Q>3.5 AU, paying special attention to the problem of mixing of both populations, such that inactive comets may be disguised as NEAs. From numerical integrations for 2×10 6 years we find that the half lifetime (where the lifetime is defined against hyperbolic ejection or collision with the Sun or the planets) of near-Earth JF comets (perihelion distances q<1.3 AU) is about 1.5×10 5 years but that they spend only a small fraction of this time (˜ a few 10 3 years) with q<1.3 AU. From numerical integrations for 5×10 6 years we find that the half lifetime of NEAs in "cometary" orbits (defined as those with aphelion distances Q>4.5 AU, i.e., that approach or cross Jupiter's orbit) is 4.2×10 5 years, i.e., about three times longer than that for near-Earth JF comets. We also analyze the problem of decoupling JF comets from Jupiter to produce Encke-type comets. To this end we simulate the dynamical evolution of the sample of observed JF comets with the inclusion of nongravitational forces. While decoupling occurs very seldom when a purely gravitational motion is considered, the action of nongravitational forces (as strong as or greater than those acting on Encke) can produce a few Enckes. Furthermore, a few JF comets are transferred to low-eccentricity orbits entirely within the main asteroid belt ( Q<4 AU and q>2 AU). The population of NEAs in cometary orbits is found to be adequately replenished with NEAs of smaller Q's diffusing outward, from which we can set an upper limit of ˜20% for the putative component of deactivated JF comets needed to maintain such a population in steady state. From this analysis, the upper limit for the average time that a JF comet in near-Earth orbit can spend as a dormant, asteroid-looking body can be estimated to be about 40% of the time spent as an active comet. More likely, JF comets in near-Earth orbits will disintegrate once (or shortly after) they end their active phases.

The nucleus of 19/P Borrelly as revealed by deep space 1

USGS Publications Warehouse

Buratti, B.; Hicks, M.; Soderblom, L.; Britt, D.; Boice, D.; Brown, R.; Nelson, R.; Oberst, J.; Owen, Timothy W.; Sandel, B.; Stern, S.A.; Thomas, N.; Yelle, R.

2002-01-01

The Deep Space 1 encounter with comet 19/P Borrelly offered the first close-up view of a comet unobscured by dust. The geometric albedo of the comet is 0.029±0.006 (with a size of 8.0 × 3.15 km), comparable to the low-albedo hemisphere of Iapetus, the lowest albedo C-type asteroids, and the Uranian rings. Albedo variegations on the body are substantial, far greater than on the handful of asteroids so far scrutinized by spacecraft. The Bond albedo of Borrelly is 0.009 ± 0.002, the lowest of any object in the Solar System. The physical photometric parameters of the comet are similar to asteroids, but the optically active portion of its regolith may be fluffier. Differences in macroscopic roughness exist on its surface: the older regions appear to be slightly less rough, as if low-lying regions are infilled with native dust. Regional differences in the single particle phase function exist, with small regions exhibiting almost isotropic functions.

The Impact Imperative: Laser Ablation for Deflecting Asteroids, Meteoroids, and Comets From Impacting the Earth

NASA Technical Reports Server (NTRS)

Campbell, Jonathan W.; Phipps, Claude; Smalley, Larry; Reilly, Jim; Boccis, Dona; Howell, Joe T., Jr. (Technical Monitor)

2002-01-01

Impacting at hypervelocity, an asteroid struck the Earth approximately 65 million years ago in the Yucatan Peninsula area. This triggered the extinction of almost 70% of the species of life on Earth including the dinosaurs. Other impacts prior to this one have caused even greater extinctions. Preventing collisions with the Earth by hypervelocity asteroids, meteoroids, and comets is the most important immediate space challenge facing human civilization. This is the Impact Imperative. We now believe that while there are about 2000 earth orbit crossing rocks greater than 1 kilometer in diameter, there may be as many as 200,000 or more objects in the 100 m size range, Can anything be done about this fundamental existence question facing our civilization? The answer is a resounding yes! By using an intelligent combination of Earth and space based sensors coupled with an infra-structure of high-energy laser stations and other secondary mitigation options, we can deflect inbound asteroids, meteoroids, and comets and prevent them from striking the Earth.

Navigation Strategies for Primitive Solar System Body Rendezvous and Proximity Operations

NASA Technical Reports Server (NTRS)

Getzandanner, Kenneth M.

2011-01-01

A wealth of scientific knowledge regarding the composition and evolution of the solar system can be gained through reconnaissance missions to primitive solar system bodies. This paper presents analysis of a baseline navigation strategy designed to address the unique challenges of primitive body navigation. Linear covariance and Monte Carlo error analysis was performed on a baseline navigation strategy using simulated data from a· design reference mission (DRM). The objective of the DRM is to approach, rendezvous, and maintain a stable orbit about the near-Earth asteroid 4660 Nereus. The outlined navigation strategy and resulting analyses, however, are not necessarily limited to this specific target asteroid as they may he applicable to a diverse range of mission scenarios. The baseline navigation strategy included simulated data from Deep Space Network (DSN) radiometric tracking and optical image processing (OpNav). Results from the linear covariance and Monte Carlo analyses suggest the DRM navigation strategy is sufficient to approach and perform proximity operations in the vicinity of the target asteroid with meter-level accuracy.

The asteroid-comet continuum from laboratory and space analyses of comet samples and micrometeorites

NASA Astrophysics Data System (ADS)

Engrand, Cécile; Duprat, Jean; Bardin, Noémie; Dartois, Emmanuel; Leroux, Hugues; Quirico, Eric; Benzerara, Karim; Remusat, Laurent; Dobrică, Elena; Delauche, Lucie; Bradley, John; Ishii, Hope; Hilchenbach, Martin

2016-10-01

Comets are probably the best archives of the nascent solar system, 4.5 Gyr ago, and their compositions reveal crucial clues on the structure and dynamics of the early protoplanetary disk. Anhydrous minerals (olivine and pyroxene) have been identified in cometary dust for a few decades. Surprisingly, samples from comet Wild2 returned by the Stardust mission in 2006 also contain high temperature mineral assemblages like chondrules and refractory inclusions, which are typical components of primitive meteorites (carbonaceous chondrites - CCs). A few Stardust samples have also preserved some organic matter of comet Wild 2 that share some similarities with CCs. Interplanetary dust falling on Earth originate from comets and asteroids in proportions to be further constrained. These cosmic dust particles mostly show similarities with CCs, which in turn only represent a few percent of meteorites recovered on Earth. At least two (rare) families of cosmic dust particles have shown strong evidences for a cometary origin: the chondritic porous interplanetary dust particles (CP-IDPs) collected in the terrestrial stratosphere by NASA, and the ultracarbonaceous Antarctic Micrometeorites (UCAMMs) collected from polar snow and ice by French and Japanese teams. Analyses of dust particles from the Jupiter family comet 67P/Churyumov-Gerasimenko by the dust analyzers on Rosetta orbiter (COSIMA, GIADA, MIDAS) suggest a relationship to interplanetary dust/micrometeorites. A growing number of evidences highlights the existence of a continuum between asteroids and comets, already in the early history of the solar system.

Studies of Asteroids and Comets

NASA Technical Reports Server (NTRS)

Bowell, Edward L. G.

1998-01-01

Research under this grant was carried out between 1989 and 1998. It comprised observational, theoretical, and computational research, mainly on asteroids. Two principal areas of research, centering on astrometry and photometry, were interrelated in their aim to study the overall structure of the asteroid belt and the orbital and physical properties of individual asteroids.

Astrometric Observations of Comets and Asteroids and Subsequent Orbital Investigations

NASA Technical Reports Server (NTRS)

Marsden, Brian G.; McCrosky, Richard E.

1997-01-01

An earlier series of photographic observations was made with the 1.5-m reflector from 1972 to 1989. The start of the series to which this report refers occurred shortly before the conversion from photographic to CCD operation in August 1989, at which point there was a dramatic increase in the productivity of the program. This is evident gives a month-by-month summary of the observations; the earlier data refer to the measurement or remeasurement of photographic plates previously taken with the same telescope. The total number of observations made was 24,423, of which 1338 were of comets. Of the 23,085 observations of asteroids, 21,529 referred to asteroids that were unnumbered when the observations were made. Since an important emphasis of the program was to improve knowledge of the orbits to the point where asteroids can be numbered, the fact that only 4262 of the observations refer to asteroids that are still unnumbered is a measure of the program's success, with 30-35 percent of all the new numberings being habitually made solely because of the recent data from the Oak Ridge program, which even at the time of McCrosky's retirement was still the fourth largest comet-asteroid astrometric program in the world.

Super-Comet or Big Asteroid Belt?

NASA Technical Reports Server (NTRS)

2005-01-01

[figure removed for brevity, see original site] Figure 1: Spectrograph of HD 69830

This graph of data from NASA's Spitzer Space Telescope demonstrates that the dust around a nearby star called HD 69830 (upper line) has a very similar composition to that of Comet Hale-Bopp. Spitzer spotted large amounts of this dust in the inner portion of the HD 69830 system.

The bumps and dips seen in these data, or spectra, represent the 'fingerprints' of various minerals. Spectra are created when an instrument called a spectrograph spreads light out into its basic parts, like a prism turning sunlight into a rainbow. These particular spectra reveal the presence of the silicate mineral called olivine, and more specifically, a type of olivine called forsterite, which is pictured in the inset box. Forsterite is a bright-green gem found on Earth, on the 'Green Sand Beach' of Hawaii among other places; and in space, in comets and asteroids.

Because the dust around HD 69830 has a very similar make-up to that of Comet Hale-Bopp, astronomers speculate that it might be coming from a giant comet nearly the size of Pluto. Such a comet may have been knocked into the inner solar system of HD 69830, where it is now leaving in its wake a trail of evaporated dust.

Nonetheless, astronomers say the odds that Spitzer has caught a 'super-comet' spiraling in toward its star - an unusual and relatively short-lived event - are slim. Instead, they favor the theory that the observed dust is actually the result of asteroids banging together in a massive asteroid belt.

The data of HD 69830's dust were taken by Spitzer's infrared spectrograph. The data of Comet Hale-Bopp were taken by the European Space Agency's Infrared Observatory Satellite. The picture of forsterite comes courtesy of Dr. George Rossman, California Institute of Technology, Pasadena.

Comet Tempel 2: Orbit, ephemerides and error analysis

NASA Technical Reports Server (NTRS)

Yeomans, D. K.

1978-01-01

The dynamical behavior of comet Tempel 2 is investigated and the comet is found to be very well behaved and easily predictable. The nongravitational forces affecting the motion of this comet are the smallest of any comet that is affected by nongravitational forces. The sign and time history of these nongravitational forces imply (1) a direct rotation of the comet's nucleus and (2) the comet's ability to outgas has not changed substantially over its entire observational history. The well behaved dynamical motion of the comet, the well observed past apparitions, the small nongravitational forces and the excellent 1988 ground based observing conditions all contribute to relatively small position and velocity errors in 1988 -- the year of a proposed rendezvous space mission to this comet. To assist in planned ground based and earth orbital observations of this comet, ephemerides are given for the 1978-79, 1983-84 and 1988 apparitions.

Internal gravity, self-energy, and disruption of comets and asteroids

NASA Astrophysics Data System (ADS)

Dobrovolskis, Anthony R.; Korycansky, D. G.

2018-03-01

The internal gravity and self-gravitational energy of a comet, asteroid, or small moon have applications to their geophysics, including their formation, evolution, cratering, and disruption, the stresses and strains inside such objects, sample return, eventual asteroid mining, and planetary defense strategies for potentially hazardous objects. This paper describes the relation of an object's self-energy to its collisional disruption energy, and shows how to determine an object's self-energy from its internal gravitational potential. Any solid object can be approximated to any desired accuracy by a polyhedron of sufficient complexity. An analytic formula is known for the gravitational potential of any homogeneous polyhedron, but it is widely believed that this formula applies only on the surface or outside of the object. Here we show instead that this formula applies equally well inside the object. We have used these formulae to develop a numerical code which evaluates the self-energy of any homogeneous polyhedron, along with the gravitational potential and attraction both inside and outside of the object, as well as the slope of its surface. Then we use our code to find the internal, external, and surface gravitational fields of the Platonic solids, asteroid (216) Kleopatra, and comet 67P/Churyumov-Gerasimenko, as well as their surface slopes and their self-gravitational energies. We also present simple spherical, ellipsoidal, cuboidal, and duplex models of Kleopatra and comet 67P, and show how to generalize our methods to inhomogeneous objects and magnetic fields. At present, only the self-energies of spheres, ellipsoids, and cuboids (boxes) are known analytically (or semi-analytically). The Supplementary Material contours the central potential and self-energy of homogeneous ellipsoids and cuboids of all aspect ratios, and also analytically the self-gravitational energy of a "duplex" consisting of two coupled spheres. The duplex is a good model for "contact binary" comets and asteroids; in fact, most comets seem to be bilobate, and might be described better as "dirty snowmen" than as "dirty snowballs".

Sources of Terrestrial Volatiles

NASA Technical Reports Server (NTRS)

Zahnle, K. J.; Dones, L.

1998-01-01

Atmospheres are found enveloping those planets and satellites best able to hold them. The obvious conclusion is that volatile escape must have played nearly as great a role as volatile supply. A consequence of this view is that volatile supplies were probably much greater than the atmospheres that remain. The likeliest candidates are sources associated with the main events of planetary accretion itself such as volatile-rich planetesimals, or direct gravitational capture of nebular gases. Late asteroidal or cometary volatile-rich veneers are attractive, but they present quantitative difficulties. Comets in particular are inadequate, because the associated mass of stray comets that would have been scattered to the Oort Cloud or beyond is excessive. This difficulty applies to Uranus-Neptune planetesimals as well as to a putative massive early Kuiper Belt. Another potential problem with comets is that the D/H ratio in the three comets for which this has been measured is about twice that of Earth's oceans. Objects falling from a much augmented ancient asteroid belt remain a viable option, but timing is an issue: Can the depopulation of the asteroid belt be delayed long enough that it makes sense to talk of asteroids as a late veneer? Early accretion of asteroids as objects scattered into the maw of infant Earth makes more sense. Another appealing candidate population of volatile-rich objects for the inner solar system would be scattered planetesimals associated with the accretion of Jupiter, for two reasons: (1) Before there was Jupiter, there was no object in the solar system capable of expelling comets efficiently, and (2) the cross section of the inner solar system to stray objects was Greater when there were m many planetesimals.

New Research by CCD Scanning for Comets and Asteroids

NASA Technical Reports Server (NTRS)

Gehrels, Tom

1997-01-01

Spacewatch was begun in 1980; its purpose is to explore the various populations of small objects within the solar system. Spacewatch provides data for studies of comets and asteroids, finds potential targets for space missions, and provides information on the environmental problem of possible impacts. Moving objects are discovered by scanning the sky with charge-coupled devices (CCDS) on the 0.9-meter Spacewatch Telescope of the University of Arizona on Kitt Peak. Each Spacewatch scan consists of three drift scan passes over an area of sky using a CCD filtered to a bandpass of 0.5-1.0 pm (approximately V+R+I with peak sensitivity at 0.7 pm). The effective exposure time for each pass is 143 seconds multiplied by the secant of the declination. The area covered by each scan is 32 arcminutes in declination by about 28 minutes of time in right ascension. The image scale is 1.05 arcseconds per pixel. Three passes take about 1.5 hours to complete and show motions of individual objects over a one hour time baseline. The limiting magnitude is about 21.5 in single scans. CCD scanning was developed by Spacewatch in the early 1980s, with improvements still being made - particularly by bringing a new 1.8-m Spacewatch Telescope on line. In the meantime, we have been finding some 30,000 new asteroids per year and applying their statistics to the study of the collisional history of the solar system. Spacewatch had found a total of 150 Near-Earth Asteroids (NEAS) and 8 new comets, and had recovered one lost comet (P/Spitaler in 1993). Spacewatch is also efficient in recovery of known comets and has detected and reported positions for more than 137,000 asteroids, mostly new ones in the main belt, including more than 10,882 asteroids designated by the Minor Planet Center (MPC).

Secular light curves of comets, II: 133P/Elst Pizarro, an asteroidal belt comet

NASA Astrophysics Data System (ADS)

Ferrín, Ignacio

2006-12-01

We present the secular light curve (SLC) of 133P/Elst-Pizarro, and show ample and sufficient evidence to conclude that it is evolving into a dormant phase. The SLC provides a great deal of information to characterize the object, the most important being that it exhibits outburst-like activity without a corresponding detectable coma. 133P will return to perihelion in July of 2007 when some of our findings may be corroborated. The most significant findings of this investigation are: (1) We have compiled from 127 literature references, extensive databases of visual colors (37 comets), rotational periods and peak-to-valley amplitudes (64 comets). 2-Dimensional plots are created from these databases, which show that comets do not lie on a linear trend but in well defined areas of these phase spaces. When 133P is plotted in the above diagrams, its location is entirely compatible with those of comets. (2) A positive correlation is found between cometary rotational periods and diameters. One possible interpretation suggest the existence of rotational evolution predicted by several theoretical models. (3) A plot of the historical evolution of cometary nuclei density estimates shows no trend with time, suggesting that perhaps a consensus is being reached. We also find a mean bulk density for comets of <ρ>=0.52±0.06 g/cm. This value includes the recently determined spacecraft density of Comet 9P/Tempel 1, derived by the Deep Impact team. (4) We have derived values for over 18 physical parameters, listed in the SLC plots, Figs. 6-9. (5) The secular light curve of 133P/Elst-Pizarro exhibits a single outburst starting at +42±4 d (after perihelion), peaking at LAG=+155±10 d, duration 191±11 d, and amplitude 2.3±0.2 mag. These properties are compatible with those of other low activity comets. (6) To explain the large time delay in maximum brightness, LAG, two hypothesis are advanced: (a) the existence of a deep ice layer that the thermal wave has to reach before sublimation is possible, or (b) the existence of a sharp polar active region pointing to the Sun at time = LAG, that may take the form of a polar ice cap, a polar fissure or even a polar crater. The diameter of this zone is calculated at ˜1.8 km. (7) A new time-age is defined and it its found that T-AGE = 80 cy for 133P, a moderately old comet. (8) We propose that the object has its origin in the main belt of asteroids, thus being an asteroid-comet hybrid transition object, an asteroidal belt comet (ABC), proven by its large density. (9) Concerning the final evolutionary state of this object, to be a truly extinct comet the radius must be less than the thermal wave depth, which at 1 AU is ˜250 m (at the perihelion distance of 133P the thermal wave penetrates only ˜130 m). Comets with radius larger than this value cannot become extinct but dormant. Thus we conclude that 133P cannot evolve into a truly extinct comet because it has too large a diameter. Instead it is shown to be entering a dormant phase. (10) We predict the existence of truly extinct comets in the main belt of asteroids (MBA) beginning at absolute magnitude ˜21.5 (diameter smaller than ˜190 m). (11) The object demonstrates that a comet may have an outburst of ˜2.3 mag, and not show any detectable coma. (12) Departure from a photometric R law is a more sensitive method (by a factor of 10) to detect activity than star profile fitting or spectroscopy. (13) Sufficient evidence is presented to conclude that 133P is the first member of a new class of objects, an old asteroidal belt comet, ABC, entering a dormant phase.

Comet or asteroid shower in the late Eocene?

PubMed

Tagle, Roald; Claeys, Philippe

2004-07-23

The passage of a comet shower approximately 35 million years ago is generally advocated to explain the coincidence during Earth's late Eocene of an unusually high flux of interplanetary dust particles and the formation of the two largest craters in the Cenozoic, Popigai and the Chesapeake Bay. However, new platinum-group element analyses indicate that Popigai was formed by the impact of an L-chondrite meteorite. Such an asteroidal projectile is difficult to reconcile with a cometary origin. Perhaps instead the higher delivery rate of extraterrestrial matter, dust, and large objects was caused by a major collision in the asteroid belt.

Implications of theories of asteroid and comet impact for policy options for management of spent nuclear fuel and high-level radioactive wastes

USGS Publications Warehouse

Trask, Newell J.

1994-01-01

Concern with the threat posed by terrestrial asteroid and comet impacts has heightened as the catastrophic consequences of such events have become better appreciated. Although the probabilities of such impacts are very small, a reasonable question for debate is whether such phenomena should be taken into account in deciding policy for the management of spent fuel and high-level radioactive waste. The rate at which asteroid or comet impacts would affect areas of surface storage of radioactive waste is about the same as the estimated rate at which volcanic activity would affect the Yucca Mountain area. The Underground Retrievable Storage (URS) concept could satisfactorily reduce the risk from cosmic impact with its associated uncertainties in addition to providing other benefits described by previous authors.

Environmental Perturbations Caused by the Impacts of Comets and Asteroids on Earth

NASA Technical Reports Server (NTRS)

Toon, Owen B.; Lawless, James G. (Technical Monitor)

1994-01-01

The extinction mechanisms proposed at the Cretaceous-Tertiary geological boundary are reviewed and related to the impact of asteroids or comets in general. For impact energies below 10(exp 4) Megatons (less than 6 x 10(exp 4) years; asteroid diameter less than 650 m), blast, earthquake, and fire may destroy local areas up to 10(exp 5) square m. Tidal waves could flood a kilometer inland over entire ocean basins. The energy range from 105 to 106 Megatons (less than 2 x 10(exp 6) years; asteroid diameter less than 3 km) is transitional. Dust lifted, sulfur released from within impacting asteroids, and soot from fires started by comets can produce climatologically significant optical depths of 10. At energies beyond 10(exp 7) Megatons, blast and earthquake damage is regional (10(exp 6) square cm). Tsunami cresting to 100 m and flooding 20 km inland will sweep the coastal zones of the world's oceans. Fires will be set globally. Light levels may drop so low from the smoke, dust and sulfate that vision is not possible. At energies approaching 10(exp 9) Megatons the ocean surface waters may be acidified by sulfur. The combination of these effects would be devastating.

Refined Rotational Period, Pole Solution, and Shape Model for (3200) Phaethon

NASA Astrophysics Data System (ADS)

Ansdell, Megan; Meech, Karen J.; Hainaut, Olivier; Buie, Marc W.; Kaluna, Heather; Bauer, James; Dundon, Luke

2014-09-01

(3200) Phaethon exhibits both comet- and asteroid-like properties, suggesting it could be a rare transitional object such as a dormant comet or previously volatile-rich asteroid. This justifies detailed study of (3200) Phaethon's physical properties as a better understanding of asteroid-comet transition objects can provide insight into minor body evolution. We therefore acquired time series photometry of (3200) Phaethon over 15 nights from 1994 to 2013, primarily using the Tektronix 2048 × 2048 pixel CCD on the University of Hawaii 2.2 m telescope. We utilized light curve inversion to (1) refine (3200) Phaethon's rotational period to P = 3.6032 ± 0.0008 hr; (2) estimate a rotational pole orientation of λ = +85° ± 13° and β = -20° ± 10° and (3) derive a shape model. We also used our extensive light curve data set to estimate the slope parameter of (3200) Phaethon's phase curve as G ~ 0.06, consistent with C-type asteroids. We discuss how this highly oblique pole orientation with a negative ecliptic latitude supports previous evidence for (3200) Phaethon's origin in the inner main asteroid belt as well as the potential for deeply buried volatiles fueling impulsive yet rare cometary outbursts.

Comparison of comet 81P/Wild 2 dust with interplanetary dust from comets.

PubMed

Ishii, Hope A; Bradley, John P; Dai, Zu Rong; Chi, Miaofang; Kearsley, Anton T; Burchell, Mark J; Browning, Nigel D; Molster, Frank

2008-01-25

The Stardust mission returned the first sample of a known outer solar system body, comet 81P/Wild 2, to Earth. The sample was expected to resemble chondritic porous interplanetary dust particles because many, and possibly all, such particles are derived from comets. Here, we report that the most abundant and most recognizable silicate materials in chondritic porous interplanetary dust particles appear to be absent from the returned sample, indicating that indigenous outer nebula material is probably rare in 81P/Wild 2. Instead, the sample resembles chondritic meteorites from the asteroid belt, composed mostly of inner solar nebula materials. This surprising finding emphasizes the petrogenetic continuum between comets and asteroids and elevates the astrophysical importance of stratospheric chondritic porous interplanetary dust particles as a precious source of the most cosmically primitive astromaterials.

Thermal alteration in carbonaceous chondrites and implications for sublimation in rock comets

NASA Astrophysics Data System (ADS)

Springmann, Alessondra; Lauretta, Dante S.; Steckloff, Jordan K.

2015-11-01

Rock comets are small solar system bodies in Sun-skirting orbits (perihelion q < ~0.15 AU) that form comae rich in mineral sublimation products, but lack typical cometary ice sublimation products (H2O, CO2, etc.). B-class asteroid (3200) Phaethon, considered to be the parent body of the Geminid meteor shower, is the only rock comet currently known to periodically eject dust and form a coma. Thermal fracturing or thermal decomposition of surface materials may be driving Phaethon’s cometary activity (Li & Jewitt, 2013). Phaethon-like asteroids have dynamically unstable orbits, and their perihelia can change rapidly over their ~10 Myr lifetimes (de León et al., 2010), raising the possibility that other asteroids may have been rock comets in the past. Here, we propose using spectroscopic observations of mercury (Hg) as a tracer of an asteroid’s thermal metamorphic history, and therefore as a constraint on its minimum achieved perihelion distance.B-class asteroids such as Phaethon have an initial composition similar to aqueously altered primitive meteorites such as CI- or CM-type meteorites (Clark et al., 2010). Laboratory heating experiments of ~mm sized samples of carbonaceous chondrite meteorites from 300K to 1200K at a rate of 15K/minute show mobilization and volatilization of various labile elements at temperatures that could be reached by Mercury-crossing asteroids. Samples became rapidly depleted in labile elements and, in particular, lost ~75% of their Hg content when heated from ~500-700 K, which corresponds to heliocentric distances of ~0.15-0.3 au, consistent with our thermal models. Mercury has strong emission lines in the UV (~ 185 nm) and thus its presence (or absence) relative to carbonaceous chondrite abundances would indicate if these bodies had perihelia in their dynamical histories inside of 0.15 AU, and therefore may have previously been Phaethon-like rock comets. Future space telescopes or balloon-borne observing platforms equipped with a UV spectrometer could potentially detect the presence or absence of strong ultraviolet mercury lines on rock comets or rock comet candidates.

Japanese Exploration to Solar System Small Bodies: Rewriting a Planetary Formation Theory with Astromaterial Connection (Invited)

NASA Astrophysics Data System (ADS)

Yano, H.

2013-12-01

Three decades ago, Japan's deep space exploration started with Sakigake and Suisei, twin flyby probes to P/Halley. Since then, the Solar System small bodies have been one of focused destinations to the Japanese solar system studies even today. Only one year after the Halley armada launch, the very first meeting was held for an asteroid sample return mission at ISAS, which after 25 years, materialized as the successful Earth return of Hayabusa , an engineering verification mission for sample return from surfaces of an NEO for the first time in the history. Launched in 2003 and returned in 2010, Hayabusa became the first to visit a sub-km, rubble-pile potentially hazardous asteroid in near Earth space. Its returned samples solved S-type asteroid - ordinary chondrite paradox by proving space weathering evidences in sub-micron scale. Between the Halley missions and Hayabusa, SOCCER concept by M-V rocket was jointly studied between ISAS and NASA; yet it was not realized due to insufficient delta-V for intact capture by decelerating flyby/encounter velocity to a cometary coma. The SOCCER later became reality as Stardust, NASA Discovery mission for cometary coma dust sample return in1999-2006. Japan has collected the second largest collection of the Antarctic meteorites and micrometeorites of the world and asteromaterial scientists are eager to collaborate with space missions. Also Japan enjoyed a long history of collaborations between professional astronomers and high-end amateur observers in the area of observational studies of asteroids, comets and meteors. Having these academic foundations, Japan has an emphasis on programmatic approach to sample returns of Solar System small bodies in future prospects. The immediate follow-on to Hayabusa is Hayabusa-2 mission to sample return with an artificial impactor from 1999 JU3, a C-type NEO in 2014-2020. Following successful demonstration of deep space solar sail technique by IKAROS in 2010-2013, the solar power sail is a deep space probe with hybrid propulsion of solar photon sail and ion engine system that will enable Japan to reach out deep interplanetary space beyond the main asteroid belt. Since 2002, Japanese scientists and engineers have been investigating the solar power sail mission to Jupiter Trojans and interdisciplinary cruising science, such as infrared observation of zodiacal light due to cosmic dust, which at the same time hit a large cross section of the solar sail membrane dust detector, concentrating inside the main asteroid belt. Now the mission design has extended from cruising and fly-by only to rendezvous and sample return options from Jupiter Trojan asteroids. Major scientific goal of Jupiter Trojan exploration is to constrain its origin between two competing hypothesis such as remnants of building blocks the Jovian system as the classic model and the second generation captured EKBOs as the planetary migration models, in which several theories are in deep discussion. Also important is to better understand mixing process of material and structure of the early Solar System just beyond snow line. The current plan involves its launch and both solar photon and IES accelerations combined with Earth and Jupiter gravity assists in 2020's, detailed rendezvous investigation of a few 10-km sized D-type asteroid among Jupiter Trojans in early 2030's and an optional sample return of its surface materials to the Earth in late 2030's.

Amor: Investigating The Triple Asteroid System 2001 SN263

NASA Astrophysics Data System (ADS)

Jones, T.; Bellerose, Julie; Lee, P.; Prettyman, T.; Lawrence, D.; Smith, P.; Gaffey, M.; Nolan, M.; Goldsten, J.; Thomas, P.; Veverka, J.; Farquhar, R.; Heldmann, J.; Reddy, V.; Williams, B.; Chartres, J.; DeRosee, R.; Dunham, D.

2010-10-01

The Amor mission will rendezvous and land at the triple Near-Earth Asteroid system (153591) 2001 SN263 and execute detailed, in-situ science investigations. The spacecraft reaches 2001 SN263 by using a two-year ΔVEGA (ΔV-Earth Gravity Assist) trajectory with a relatively low launch C3 of 33.5 km2/s2. Rendezvous will enable reconnaissance activities including global and regional imaging, shape modeling, system dynamics, and compositional mapping. After landing, Amor will conduct in-situ imaging (panoramic to microscopic scale) and compositional measurements to include elemental abundance. The main objectives are to 1) establish in-situ the long-hypothesized link between C-type asteroids and the primitive carbonaceous chondrite (CC) meteorites, 2) investigate the nature, origin and evolution of C-type asteroids, and 3) investigate the origin and evolution of a multiple asteroid system. The mission also addresses the distribution of volatiles and organic materials, impact hazards, and resources for future exploration. Amor is managed by NASA Ames Research Center in partnership with Orbital Sciences, KinetX, MDA, and Draper with heritage instruments provided by Ball Aerospace, JHU/APL, and Firestar Engineering. The science team brings experience from NEAR, Hayabusa, Deep Impact, Dawn, LCROSS, Kepler, and Mars missions. In this paper, we describe the science, mission design, and main operational challenges of performing in-situ science at this triple asteroid system. Challenges include landing on the asteroid components, thermal environment, short day-night cycles, and the operation of deployed instruments in a low gravity (10^-5 g) environment.

Ion Beam Deflection (AKA Push-Me/Pull-You)

NASA Technical Reports Server (NTRS)

Brophy, John

2013-01-01

The Ion Beam Deflection provides the following potential advantages over other asteroid deflection systems. Like the gravity tractor, it doesn't require despinning of the asteroid. Unlike the gravity tractor, it provides a significantly higher coupling force that is independent of the asteroid size. The concept could be tested as part of the baseline Asteroid Redirect Robotic Mission. The thrust and total impulse are entirely within the design of the SEP vehicle. The total impulse is potentially competitive with kinetic impactors and eliminates the need for a second rendezvous spacecraft.?Gridded ion thrusters provide beam divergence angles of a few degrees enabling long stand-off distances from the asteroid. Mitigating control issues. Minimizing back-sputter contamination risks

Planetary Defense: Options for Deflection of Near Earth Objects

NASA Technical Reports Server (NTRS)

Adams, R. B.; Statham, G.; Hopkins, R.; Chapman, J.; White, S.; Bonometti, J.; Alexander, R.; Fincher, S.; Polsgrove, T.; Kalkstein, M.

2003-01-01

Several recent near-miss encounters with asteroids and comets have focused attention on the threat of a catastrophic impact with the Earth. This document reviews the historical impact record and current understanding of the number and location of Near Earth Objects (NEO's) to address their impact probability. Various ongoing projects intended to survey and catalog the NEO population are also reviewed. Details are then given of an MSFC-led study, intended to develop and assess various candidate systems for protection of the Earth against NEOs. An existing program, used to model the NE0 threat, was extensively modified and is presented here. Details of various analytical tools, developed to evaluate the performance of proposed technologies for protection against the NEO threat, are also presented. Trajectory tools, developed to model the outbound path a vehicle would take to intercept or rendezvous with a target asteroid or comet, are described. Also, details are given of a tool that was created to model both the un-deflected inbound path of an NE0 as well as the modified, post-deflection, path. The number of possible options available for protection against the NE0 threat was too numerous for them to all be addressed within the study; instead, a representative selection were modeled and evaluated. The major output from this work was a novel process by which the relative effectiveness of different threat mitigation concepts can be evaluated during future, more detailed, studies. In addition, several new or modified mathematical models were developed to analyze various proposed protection systems. A summary of the major lessons learned during this study is presented, as are recommendations for future work. It is hoped that this study will serve to raise the level attention about this very real threat and also demonstrate that successful defense is both possible and practicable, provided appropriate steps are taken.

Orbit-dependent spectral trends for the near-Earth asteroid population

NASA Astrophysics Data System (ADS)

Fevig, Ronald Adrey

Results of visible to near-infrared spectrophotometric observations of 55 near- Earth asteroids (NEAs) are reported. The observing techniques, instrumentation, and method of data analysis are described. A new asteroid classification method that directly compares these NEA spectra with spectral features of meteorites is presented. Two major siliceous groups (having discernible "1-mm" absorptions) result from this method, OC-likes which match the spectra of ordinary chondrites and S-types. The dataset shows a preponderance of spectra consistent with ordinary chondrites (23 NEAs), as well as S-types (19), 2 with spectra consistent with black ordinary chondrites, 2 R-types, and 9 that show no 1-mm absorption. The spectral characteristics of the siliceous S-type and OC-like asteroids blend together, providing evidence that S-type asteroids are simply ordinary chondrites whose surface has been modified by weathering. This helps resolve the long standing question of the lack of main belt asteroids having spectra matching ordinary chondrite meteorites. Main belt asteroids have on average much older surfaces while NEAs that exhibit OC-like spectra have younger surfaces. It was found that fresh objects having spectra consistent with ordinary chondrites (1) occupy mostly highly eccentric Apollo orbits which encounter a strong collisional environment in the asteroid main-belt, (2) may have been recently injected into high eccentricity orbits, or (3) have suffered tidal disruption. S-type NEAs reside primarily in orbits that do not cross the asteroid main-belt. This orbit dependent trend is verified by using the larger NEA dataset of Binzel et al. (2004a). Nine NEAs from this survey exhibiting no 1-mm absorption can be associated with extinct comets, iron meteorites or enstatite meteorites. It is shown that most of these NEAs must be extinct comets, implying a considerably larger fraction of comets among the NEA population than previously thought. A correlation of these objects with low inclination orbits is found. This study finds that the NEA population is divided roughly as follows: ~40 % fresh ordinary chondrites, ~35% S-types, ~20% extinct comet candidates, and ~5% in minor classes. This work may guide NEA mitigation planning should such an emergency arise.

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.

The Uncertain Nature of Cometary Motions

NASA Technical Reports Server (NTRS)

Yeomans, Donald K.

1997-01-01

The number of active short- and long-periodic comets crossing the Earth's orbit each year is less than 10 percent of the corresponding number of asteroids crossing the Earth's orbit. However, the higher relative velocities of comets with respect to the Earth and the uncertainties associated with accurately computing their future trajectories can cause considerable problems when assessing the risks of Earth-crossing objects. Unlike asteroids, the motions of active comets are often affected by so-called nongravitational (outgassing) forces that are imperfectly modeled. In addition, the astrometric optical observations that are used to refine a comet's orbit are often imprecise because a comet's center of mass can be hidden by atmospheric gas and dust. For long-period comets, there is the additional problem of having to base orbital solutions on relatively short observational data intervals. Long-term numerical integrations extending two centuries into the future have been carried out to investigate upcoming Earth-close approaches by known periodic comets. Error analyses and impact probabilities have been computed for those comets that will pass closest to the Earth. Although there are no known comets that will make dangerously close Earth approaches in the next two centuries, there are a few objects that warrant future monitoring.

NEOWISE View of Comet Christensen

NASA Image and Video Library

2015-11-23

An infrared view from NASA's NEOWISE mission of the Oort cloud comet C/2006 W3 (Christensen). The spacecraft observed this comet on April 20th, 2010 as it traveled through the constellation Sagittarius. Comet Christensen was nearly 370 million miles (600 million kilometers) from Earth at the time. The image is half of a degree of the sky on each side. Infrared light with wavelengths of 3.4, 12 and 22 micron channels are mapped to blue, green, and red, respectively. The signal at these wavelengths is dominated primarily by the comet's dust thermal emission, giving it a golden hue. The WISE spacecraft was put into hibernation in 2011 upon completing its goal of surveying the entire sky in infrared light. WISE cataloged three quarters of a billion objects, including asteroids, stars and galaxies. In August 2013, NASA decided to reinstate the spacecraft on a mission to find and characterize more asteroids. http://photojournal.jpl.nasa.gov/catalog/PIA20118

Comet and asteroid hazard to the terrestrial planets

NASA Astrophysics Data System (ADS)

Ipatov, S. I.; Mather, J. C.

2004-01-01

We estimated the rate of comet and asteroid collisions with the terrestrial planets by calculating the orbits of 13,000 Jupiter-crossing objects (JCOs) and 1300 resonant asteroids and computing the probabilities of collisions based on random-phase approximations and the orbital elements sampled with a 500 years step. The Bulirsh-Stoer and a symplectic orbit integrator gave similar results for orbital evolution, but may give different collision probabilities with the Sun. A small fraction of former JCOs reached orbits with aphelia inside Jupiter's orbit and some reached Apollo orbits with semi-major axes less than 2 AU, Aten orbits and inner-Earth orbits (with aphelia less than 0.983 AU) and remained there for millions of years. Though less than 0.1% of the total, these objects were responsible for most of the collision probability of former JCOs with Earth and Venus. We conclude that a significant fraction of near-Earth objects could be extinct comets that came from the trans-Neptunian region or most of such comets disintegrated during their motion in near-Earth object orbits.

Research in planetary astronomy and operation of the Mauna Kea Observatory

NASA Technical Reports Server (NTRS)

Cruikshank, Dale P.

1988-01-01

Spectroscopic studies with ground-based telescopes at low resolution can give compositional information of the surfaces and atmospheres of planets, satellites, asteroids, and comets. Solid state absorptions in ices and minerals are measurable by the low-resolution spectrophotometric technique. This program includes spectroscopy of distant comets, asteroids of particular interest in various contexts (planet crossers, outer main belt, trojans, etc.), Pluto and Charon, and planetary satellites of particular interest (Iapetus, Io, Uranian satellites, etc.). In the case of planets, satellites, and comets, emphasis is placed on volatiles (ices and organics), while for asteroids the stress is on mineralogy and the connection with the meteorites. New spectra show that the IR signature of Triton has changed since 1980, in that the methane bands are significantly weaker. Spectral evidence for the presence of molecular nitrogen remains convincing. Also, the brightness of Triton throughout its orbital cycle was measured to higher precision than before and was found to be constant to better than 0.02 mag. Suggestive spectral evidence was found for the presence of the C-H stretching mode band in diffuse reflection on asteroid 130 Elektra.

The 1973 report and recommendations of the NASA Science Advisory Committee on Comets and Asteroids

NASA Technical Reports Server (NTRS)

Atkins, K. (Editor)

1973-01-01

The present day knowledge is reported of comets and asteroids and recommendations for a development program needed to provide instruments to achieve certain scientific objectives are also presented. Discussions include reports on the primary experiments and instruments, the instruments of potential applicability, mission classes and parameters, mission opportunities, and vehicular technology. An annotated bibliography and recommendations for flight projects, propulsion systems, and experiment development are included.

Where Do Comets Come From?

ERIC Educational Resources Information Center

Van Flandern, Tom

1982-01-01

Proposes a new origin for comets in the solar system, namely, that comets originated in the breakup of a body orbiting the sun in or near the present location of the asteroid belt in the relatively recent past. Predictions related to the theory are discussed. (Author/JN)

Comets - Groundbased observations of spacecraft mission candidates

NASA Technical Reports Server (NTRS)

Osip, David J.; Schleicher, David G.; Millis, Robert L.

1992-01-01

Ground-based narrowband photometry results are presented for nine candidate comets for flyby and/or rendezvous missions. The comets include Churyumov-Gerasimenko, d'Arrest, Encke, Grigg-Skjellerup, Honda-Mrkos-Pajdusakova, Kopff, Tempel 1, Tempel 2, and Wild 2. On the basis of measured OH production rates and a model of the sublimation of water from the surface, limits are derived on the size of each cometary nucleus. A detailed analysis of the characteristics of these nine viable mission candidates can furnish the bases for the prioritization of targets of prospective missions.

Rosetta/VIRTIS-M spectral data: Comet 67P/CG compared to other primitive small bodies.

NASA Astrophysics Data System (ADS)

De Sanctis, M. C.; Capaccioni, F.; Filacchione, G.; Erard, S.; Tosi, F.; Ciarniello, M.; Raponi, A.; Piccioni, G.; Leyrat, C.; Bockelée-Morvan, D.; Drossart, P.; Fornasier, S.

2014-12-01

VIRTIS-M, the Visible InfraRed Thermal Imaging Spectrometer, onboard the Rosetta Mission orbiter (Coradini et al., 2007) acquired data of the comet 67P/Churyumov-Gerasimenko in the 0.25-5.1 µm spectral range. The initial data, obtained during the first mission phases to the comet, allow us to derive albedo and global spectral properties of the comet nucleus as well as spectra of different areas on the nucleus. The characterization of cometary nuclei surfaces and their comparison with those of related populations such as extinct comet candidates, Centaurs, near-Earth asteroids (NEAs), trans-Neptunian objects (TNOs), and primitive asteroids is critical to understanding the origin and evolution of small solar system bodies. The acquired VIRTIS data are used to compare the global spectral properties of comet 67P/CG to published spectra of other cometary nuclei observed from ground or visited by space mission. Moreover, the spectra of 67P/Churyumov-Gerasimenko are also compared to those of primitive asteroids and centaurs. The comparison can give us clues on the possible common formation and evolutionary environment for primitive asteroids, centaurs and Jupiter-family comets. Authors acknowledge the funding from Italian and French Space Agencies. References: Coradini, A., Capaccioni, F., Drossart, P., Arnold, G., Ammannito, E., Angrilli, F., Barucci, A., Bellucci, G., Benkhoff, J., Bianchini, G., Bibring, J. P., Blecka, M., Bockelee-Morvan, D., Capria, M. T., Carlson, R., Carsenty, U., Cerroni, P., Colangeli, L., Combes, M., Combi, M., Crovisier, J., De Sanctis, M. C., Encrenaz, E. T., Erard, S., Federico, C., Filacchione, G., Fink, U., Fonti, S., Formisano, V., Ip, W. H., Jaumann, R., Kuehrt, E., Langevin, Y., Magni, G., McCord, T., Mennella, V., Mottola, S., Neukum, G., Palumbo, P., Piccioni, G., Rauer, H., Saggin, B., Schmitt, B., Tiphene, D., Tozzi, G., Space Science Reviews, Volume 128, Issue 1-4, 529-559, 2007.

Advanced Navigation Strategies For Asteroid Sample Return Missions

NASA Technical Reports Server (NTRS)

Getzandanner, K.; Bauman, J.; Williams, B.; Carpenter, J.

2010-01-01

Flyby and rendezvous missions to asteroids have been accomplished using navigation techniques derived from experience gained in planetary exploration. This paper presents analysis of advanced navigation techniques required to meet unique challenges for precision navigation to acquire a sample from an asteroid and return it to Earth. These techniques rely on tracking data types such as spacecraft-based laser ranging and optical landmark tracking in addition to the traditional Earth-based Deep Space Network radio metric tracking. A systematic study of navigation strategy, including the navigation event timeline and reduction in spacecraft-asteroid relative errors, has been performed using simulation and covariance analysis on a representative mission.

Roadmap of next generation minor body explorations in Japan

NASA Astrophysics Data System (ADS)

Yano, H.

As of the early 2004, more than 250,000 minor bodies in the solar system have been detected. Among them, several thousands of asteroids are determined orbital elements well and even multi-band spectroscopic observation from ground enables us to classify taxonomy of them in statistically valid numbers. On the other hand, there have been several 10,000s of meteorite and cosmic dust samples already collected in the terrestrial environment. Thus, asteroid studies in statistical manners are practically conducted by ground observation and meteoritic analyses. It is a unique contribution of planetary exploration to provide the ground truth which bridges between abundant database of the ground observation and that of the meteoritic analyses, by bringing samples back to the Earth from a particular asteroid investigated in-situ. In May 2003, JAXA/ISAS successfully launched the Hayabusa (MUSES-C) spacecraft as the first kind of such minor body exploration, which will bring surface samples of an S-type NEO back to the Earth in mid 2007. Many of Japanese planetary scientists hope to advance such sample return strategies as their new expertise in the post-Hayabusa era. Now the ISAS new minor body exploration working group is about to start. Mission candidates include multiple sample returns from known spectra asteroids, in order to complete the asteroid taxonomy-meteoritic connection issue as early as possible (next 10-20 years) with possible international collaborations. One of such ideas is the multiple rendezvous sample return mission to known spectra NEOs of both primitive types (i.e., C, P/D) and differentiated types (e.g., V, M). Another is fly-by investigation and sample collection of multiple asteroids that belong to a single main-belt family. It will provide direct information of the interior as well as collisional history of their parent body, a refractory planetesimal disrupted by mutual collisions in the early stage of the Solar System evolution. One scenario targets the Koronis family including the Ida-Gaspra system, the only family asteroid visited by spacecraft in the past, and its dust band. Another aims the Nysa-Polana Family, which has several spectral types. Also what ISAS is planning is the solar powered sail mission which will make fly-by observations of main belt asteroids as well as Jovian Trojan asteroids, most of which are D-type asteroids with the absence of water absorption lines. Understanding generic connections among the Trojans, short-period cometary nucleus and the outermost D-type asteroids in the main belt may be a clue of how to distinguish between asteroids and comets, depending upon where they originated with respect to heliocentric distance in the early solar system.

ESA confirms ROSETTA and FIRST in its long-term science programme

NASA Astrophysics Data System (ADS)

1993-11-01

ROSETTA was originally conceived as a comet-nucleus sample-return mission that should have brought back cometary material to Earth to be able to study it with the most advanced laboratory analysis techniques available. The original mission could not be implemented as it was too ambitious and too complex. Therefore in 1992 the concept had to be revised. The mission was reconsidered as being performed by ESA alone on the basis of European technology and the Ariane 5 launch capability. However, the opportunity for other agencies to join and augment the scientific return was left open, and international partners have already indicated to ESA their interest to join. The new baseline mission is a rendezvous with a comet and at least one (most probably two) flybys of asteroids. After gravity-assist manoeuvres at the Earth and Mars or Venus to acquire the necessary energy to reach the comet at its aphelion (the part of the orbit farthest from the Sun), the spacecraft will stay with the comet along its trajectory into the inner solar system through perihelion (the orbital point nearest to the Sun) to study the material that constitutes the comet, and the cometary processes that evolve with the decreasing distance from the Sun. A Surface Science Station will be deployed onto the comets' nucleus surface to provide the means for in-situ studies of the nucleus. The mission retains as far as possible the objectives of the original comet-nucleus sample-return mission and concentrates on the in-situ investigations of cometary matter and the structure of the nucleus. "As we cannot bring the cometary material into our terrestrial laboratories, we will take our laboratories to the comet" said Dr. Roger Bonnet, ESA Director of Science. Potential target comets are Schwassmann- Wachmann 3, Wirtanen, Finlay and Brooks 2 for a launch in the time interval 2002-2004. "Both teams for ROSETTA and FIRST" added Dr. Bonnet, "defined excellent missions with exciting prospects for the science to be achieved. For programmatic reasons ROSETTA will be implemented as Cornerstone 3, following Cluster and SOHO and XMM". "However", he continued, "the work on FIRST will proceed at a very high level to further develop the critical technologies, like for instance the 3 m telescope mirror, the coolers and the detectors. The major elements of the Horizon 2000 science programme are now under way and we will start the process to define the 'post-Horizon 2000' programme".

Main-belt asteroid exploration - Mission options for the 1990s

NASA Technical Reports Server (NTRS)

Yen, C.-W. L.

1982-01-01

Mission configurations, propulsion systems, and target bodies for possible NASA asteroid exploration projects are examined. Noting that an announced delay in the development of a solar electric propulsion system has led to a consideration of chemical rocket systems, asteroid missions are grouped in terms of five potential areas for investigation, each successively further from the sun. The Shuttle-launched IUS is suggested as the prime candidate for boosting probes into trajectories for asteroid rendezvous with a number of the 3000 known asteroids. Planetary swingbys are mentioned as the only suitable method for satisfying the large energy requirements of the asteroid missions. Performance analyses are presented of the IUS 2-stage/Star-48 and Centaur vehicles, and sample missions to Fortuna, Anahita, and Urania in 1990 and further missions to the middle, outer, and Trojans asteroids are outlined.

Mission operations for unmanned nuclear electric propulsion outer planet exploration with a thermionic reactor spacecraft.

NASA Technical Reports Server (NTRS)

Spera, R. J.; Prickett, W. Z.; Garate, J. A.; Firth, W. L.

1971-01-01

Mission operations are presented for comet rendezvous and outer planet exploration NEP spacecraft employing in-core thermionic reactors for electric power generation. The selected reference missions are the Comet Halley rendezvous and a Jupiter orbiter at 5.9 planet radii, the orbit of the moon Io. The characteristics of the baseline multi-mission NEP spacecraft are presented and its performance in other outer planet missions, such as Saturn and Uranus orbiters and a Neptune flyby, are discussed. Candidate mission operations are defined from spacecraft assembly to mission completion. Pre-launch operations are identified. Shuttle launch and subsequent injection to earth escape by the Centaur D-1T are discussed, as well as power plant startup and the heliocentric mission phases. The sequence and type of operations are basically identical for all missions investigated.

Agile Science Operations: A New Approach for Primitive Exploration Bodies

NASA Technical Reports Server (NTRS)

Chien, Steve A.; Thompson, David R.; Castillo-Rogez, Julie C.; Doyle, Richard; Estlin, Tara; Mclaren, David

2012-01-01

Primitive body exploration missions such as potential Comet Surface Sample Return or Trojan Tour and Rendezvous would challenge traditional operations practices. Earth-based observations would provide only basic understanding before arrival and many science goals would be defined during the initial rendezvous. It could be necessary to revise trajectories and observation plans to quickly characterize the target for safe, effective observations. Detection of outgassing activity and monitoring of comet surface activity are even more time constrained, with events occurring faster than round-trip light time. "Agile science operations" address these challenges with contingency plans that recognize the intrinsic uncertainty in the operating environment and science objectives. Planning for multiple alternatives can significantly improve the time required to repair and validate spacecraft command sequences. When appropriate, time-critical decisions can be automated and shifted to the spacecraft for immediate access to instrument data. Mirrored planning systems on both sides of the light-time gap permit transfer of authority back and forth as needed. We survey relevant science objectives, identifying time bottlenecks and the techniques that could be used to speed missions' reaction to new science data. Finally, we discuss the results of a trade study simulating agile observations during flyby and comet rendezvous scenarios. These experiments quantify instrument coverage of key surface features as a function of planning turnaround time. Careful application of agile operations techniques can play a significant role in realizing the Decadal Survey plan for primitive body exploration

Discovery of Main-Belt Comet P/2006 VW139 by Pan-STARRS1

NASA Astrophysics Data System (ADS)

Hsieh, H. H.; Yang, B.; Haghighipour, N.; Kaluna, H. M.; Fitzsimmons, A.; Denneau, L.; Novakovic, B.; Jedicke, R.; Wainscoat, R. J.; Armstrong, J. D.; Duddy, S. R.; Lowry, S. C.; Trujillo, C. A.; Micheli, M.; Keane, J. V.; Urban, L.; Riesen, T.; Meech, K. J.; Abe, S.; Cheng, Y. C.; Chen, W. P.; Granvik, M.; Grav, T.; Ip, W. H.; Kinoshita, D.; Kleyna, J.; Lacerda, P.; Lister, T.; Milani, A.; Tholen, D. J.; Veres, P.; Lisse, C. M.; Kelley, M. S.; Fernandez, Y. R.; Bhatt, B. C.; Sahu, D. K.; Kaiser, N.; Chambers, K. C.; Hodapp, K. W.; Magnier, E. A.; Price, P. A.; Tonry, J. L.

2012-05-01

We describe the discovery of comet-like activity in main-belt asteroid (300163) 2006 VW139 (later re-designated as Comet P/2006 VW139) by Pan-STARRS1. We also detail follow-up photometric, spectroscopic, and dynamical analyses of the object.

The contribution of comets in Near-Earth Object and Main Belt populations and the role of collisions in the physical properties of members of these populations.

NASA Astrophysics Data System (ADS)

Michel, P.

2008-09-01

The population of Near-Earth Objects (NEOs) is composed of small bodies of various origins. Groundbased observational programs have been developed to perform their inventory and to determine their physical properties. However, these observations contain many biases and the total population of NEOs with diameters down to a few hundreds of meters has not been identified yet. In recent years, the main sources of NEOs have been characterized [1]. Most of these bodies come from the asteroid main belt and the Jupiter-family comets and their source regions are linked to transport mechanisms (mean motion and secular resonances, slow diffusion mechanisms) to the NEO-space. It has then been possible to construct a complete model of the steady-state orbital, size and albedo distribution of NEOs and to determine the level of contribution of each of their sources, including the contribution of Jupiter-family comets. However, nothing is known regarding the contribution of longperiod comets. Physical observations have been conducted in order to identify potential dormant or extinct comets among small bodies in the NEO population and to determine the fraction of "comet candidates within the total NEO population. Combining the results of these observations with our model of NEO population to evaluate source region probabilities [1], it was found that 8 +/- 5% of the total asteroid-like NEO population may have originated as comets from the outer Solar System [2]. In the population of Main Belt (MB) asteroids, three members are known to display transient comet-like physical characteristics, including prolonged periods of dust emission leading to the formation of radiation pressure-swept tails [3]. These physical properties are most naturally explained as the result of sub-limation of near-surface ice from what are, dynamically, mainbelt asteroids (hence the name "main-belt comets" (MBCs) or, equivalently "icy asteroids"). No pausible dynamical path to the asteroid belt from the cometary reservoirs in the Oort cloud or Kuiper belt has been established. Thus, we may have an unsuspected icy region closer to the Sun than expected. However, it has also been suggested that numerous comets may have been captured during a violent period of planetary orbital evolution in the early stages of our Solar System [4]. Most of these bodies experience collisions during their lifetime, which can either disrupt them or modify their physical properties. In particular, collisions are suspected to be the triggering mechanism for the activation of MBCs. Thus the collisional process needs a good understanding in order to determine its contribution in the evolution of these small bodies, as a function of their physical properties. We have recently made a major improvement in the simulations of a small body disruption by introducing a model of fragmentation of porous material which will allows us to study the impact process on cometary bodies [5]. Moreover, for bodies dominated by gravity, our simulations includes the explicit computation of the formation of aggregates during the gravitational reaccumulation of small fragments, allowing us to obtain information on their spin, the number of boulders composing them or lying on their surface, and their shape. We will present the first and preliminary results of this process taking as examples some asteroid families that we reproduced successfully with our previous simulations [6], [7], [8], [9], [10], and their possible implications on the properties of small bodies generated by a disruption. Such information can for instance be compared with data provided by the Japanese space mission Hayabusa of the asteroid Itokawa, a body now understood to be a fragment of a larger parent body. For the population of comets, improving our understanding of their collisional response can then allow us to better characterize their collisional evolution, lifetime and other properties [11] which can have some implications on their contribution in "asteroidal" populations. It is also clear that future space missions to small bodies devoted to precise insitu analysis and sample return will allow us to improve our understanding on the physical properties of these objects, and to check whether our theoretical and numerical works are valid.

Physical studies of minor planets

NASA Technical Reports Server (NTRS)

Gehrels, T. (Editor)

1971-01-01

Astronomical observations of the asteroids are discussed. The origin of asteroids and their interrelationships with comets, meteorites, and meteors are considered. Possible space missions and further topics of research are also discussed.

Cratering rates on the Galilean satellites.

PubMed

Zahnle, K; Dones, L; Levison, H F

1998-12-01

We exploit recent theoretical advances toward the origin and orbital evolution of comets and asteroids to obtain revised estimates for cratering rates in the jovian system. We find that most, probably more than 90%, of the craters on the Galilean satellites are caused by the impact of Jupiter-family comets (JFCs). These are comets with short periods, in generally low-inclination orbits, whose dynamics are dominated by Jupiter. Nearly isotropic comets (long period and Halley-type) contribute at the 1-10% level. Trojan asteroids might also be important at the 1-10% level; if they are important, they would be especially important for smaller craters. Main belt asteroids are currently unimportant, as each 20-km crater made on Ganymede implies the disruption of a 200-km diameter parental asteroid, a destruction rate far beyond the resources of today's asteroid belt. Twenty-kilometer diameter craters are made by kilometer-size impactors; such events occur on a Galilean satellite about once in a million years. The paucity of 20-km craters on Europa indicates that its surface is of order 10 Ma. Lightly cratered surfaces on Ganymede are nominally of order 0.5-1.0 Ga. The uncertainty in these estimates is about a factor of five. Callisto is old, probably more than 4 Ga. It is too heavily cratered to be accounted for by the current flux of JFCs. The lack of pronounced apex-antapex asymmetries on Ganymede may be compatible with crater equilibrium, but it is more easily understood as evidence for nonsynchronous rotation of an icy carapace. c 1998 Academic Press.

Autonomous Deep-Space Optical Navigation Project

NASA Technical Reports Server (NTRS)

D'Souza, Christopher

2014-01-01

This project will advance the Autonomous Deep-space navigation capability applied to Autonomous Rendezvous and Docking (AR&D) Guidance, Navigation and Control (GNC) system by testing it on hardware, particularly in a flight processor, with a goal of limited testing in the Integrated Power, Avionics and Software (IPAS) with the ARCM (Asteroid Retrieval Crewed Mission) DRO (Distant Retrograde Orbit) Autonomous Rendezvous and Docking (AR&D) scenario. The technology, which will be harnessed, is called 'optical flow', also known as 'visual odometry'. It is being matured in the automotive and SLAM (Simultaneous Localization and Mapping) applications but has yet to be applied to spacecraft navigation. In light of the tremendous potential of this technique, we believe that NASA needs to design a optical navigation architecture that will use this technique. It is flexible enough to be applicable to navigating around planetary bodies, such as asteroids.

Testing interconnected VLSI circuits in the Big Viterbi Decoder

NASA Technical Reports Server (NTRS)

Onyszchuk, I. M.

1991-01-01

The Big Viterbi Decoder (BVD) is a powerful error-correcting hardware device for the Deep Space Network (DSN), in support of the Galileo and Comet Rendezvous Asteroid Flyby (CRAF)/Cassini Missions. Recently, a prototype was completed and run successfully at 400,000 or more decoded bits per second. This prototype is a complex digital system whose core arithmetic unit consists of 256 identical very large scale integration (VLSI) gate-array chips, 16 on each of 16 identical boards which are connected through a 28-layer, printed-circuit backplane using 4416 wires. Special techniques were developed for debugging, testing, and locating faults inside individual chips, on boards, and within the entire decoder. The methods are based upon hierarchical structure in the decoder, and require that chips or boards be wired themselves as Viterbi decoders. The basic procedure consists of sending a small set of known, very noisy channel symbols through a decoder, and matching observables against values computed by a software simulation. Also, tests were devised for finding open and short-circuited wires which connect VLSI chips on the boards and through the backplane.

Background and applications of astrodynamics for space missions of the johns hopkins applied physics laboratory.

PubMed

Dunham, David W; Farquhar, Robert W

2004-05-01

This paper describes astrodynamic techniques applied to develop special orbital designs for past and future space missions of the Applied Physics Laboratory (APL) of Johns Hopkins University, and background about those techniques. The paper does not describe the long history of low Earth-orbiting missions at APL, but rather concentrates on the astrodynamically more interesting high-altitude and interplanetary missions that APL has undertaken in recent years. The authors developed many of their techniques in preparation for, and during, the Third International Sun-Earth Explorer (ISEE-3) halo orbit mission while they worked for the Goddard Space Flight Center (GSFC) of NASA during the 1970s and 1980s. Later missions owed much to the ground breaking work of the trajectory designs for ISEE-3 (later known as the International Cometary Explorer, or ICE). This experience, and other new ideas, were applied to the APL near Earth asteroid rendezvous (NEAR) and comet nucleus tour (CONTOUR) discovery missions, as well as to APL's future MESSENGER, STEREO, and New Horizons missions. These will be described in the paper.

Common Infrastructure for Neo Scientific and Planetary Defense Missions

NASA Technical Reports Server (NTRS)

Adams, Robert; Wilks, Rodney

2009-01-01

While defending the Earth against collisions with asteroids and comets has garnered increasing attention over the past few decades, our knowledge of the threats and methods of mitigation remain inadequate. There exists a considerable gap in knowledge regarding the size, composition, location, internal structure and formation of near earth asteroids and comets. Although estimates have been made, critical experiments have not yet been conducted on the effectiveness of various proposed mitigation techniques. Closing this knowledge gap is of interest to both the planetary defense and planetary science communities. Increased scientific knowledge of asteroid and comet composition and structure can confirm or advance current theories about the formation of the solar system. This proposal suggests a joint effort between these two communities to provide an economical architecture that supports multiple launches of characterization and mitigation payloads with minimal response time. The science community can use this architecture for characterization missions of opportunity when multiple scientific targets or targets of uncommon scientific value present themselves, while the planetary defense community would be able to fire characterization or mitigation payloads at targets that present a threat to the Earth. Both communities would benefit from testing potential mitigation techniques, which would reveal information on the internal structure of asteroids and comets. In return, the Earth would have the beginnings of a viable response system should an impact threat prove real in the near future.

Comets, Asteroids, Meteorites, and the Origin of the Biosphere

NASA Technical Reports Server (NTRS)

Hoover, Richard B.

2006-01-01

During the past few decades, the delivery of water, organics, and prebiotic chemicals to the Biosphere of Earth during the Hadean (4.5-3.8 Ga) period of heavy bombardment by comets and asteroids has become more widely accepted. Comets are still largely regarded as frigid, pristine bodies of protosolar nebula material that are devoid of liquid water and therefore unsuitable for life. Complex organic compounds have been observed in comets and on the water-rich asteroid 1998 KY26 and near IR observations have indicated the presence of crystalline water ice and ammonia hydrate on the large Kuiper Belt object (50000) Quaoar that has resurfacing suggesting cryovolcanic outgassing. Spacecraft observations of the chemical compositions and characteristics of the nuclei of several comets (Halley, Borrelly, Wild 2, and Tempel 1) have shown that comets contain complex organic chemicals; that water is the predominant volatile; and that extremely high temperatures (approx. 350-400 K) can be reached on the surfae of the very black (albedo approx. 0.03) nuclei of comets when they approach the Sun. Impact craters and pinnacles observed on comet Wild 2 suggest a thick crust. Episodic outbursts and jets from the nuclei of several comets indicate that localized regimes of liquid water and water vapor can periodically exist beneath the comet crust. The Deep Impact mission found the temperature of the nucleus of comet Tempel 1 at 1.5 AU varied from a minimum of 280 plus or minus 8 K the 330K (57 C) on the sunlit side. In this paper it is argued that that pools and films of liquid water exist (within a wide range of temperatures) in cavities and voids just beneath the hot, black crust. The possibility of liquid water existing over a wide range of temperatures significantly enhances the possibility that comets might contain niches suitable for the growth of microbial communities and ecosystems. These regimes would be ideal for the growth of psychrophilic, mesophilic, and thermophilic photoautotrophs and chemolithotrophs such as the motile filamentous cyanobacteria (e.g., Calothrix, Oscillatoria, Phormidium, and Spirulina) that grow in geothermal springs and geysers of Earth at temperatures ranging fiom 320K to 345K and are also found growing in cold polar desert soils. The mineralized remains of morphotypes of all of these cyanobacteria have also been found in the Orgueil CI1 and the Murchison CN2 carbonaceous meteorites that may derive from cometary parent bodies. Observational results that support the hypothesis that liquid water can in active regions just beneath the surface of comets and that comets, carbonaceous meteorites, and asteroids may have played a significant role in the origin and evolution of the Biosphere and in the distribution of microbial life throughout the Solar System.

Low Cost Multiple Near Earth Object Missions

NASA Astrophysics Data System (ADS)

Smith, D. B.; Klaus, K.; Kaplan, M.

2009-12-01

Commercial spacecraft are available with efficient high power solar arrays and hybrid propulsion systems (Chemical and Solar Electric) that make possible multiple Near Earth Object Missions within Discovery budget limits. Our analysis is based on the Geosynchronous Transfer Orbit Capability (GTOC-3) solution. GTOC-3 assumptions: - Escape from Earth, rendezvous with 3 asteroids, then rendezvous with Earth - Departure velocity below 0.5 km/s - Launch between 2016 and 2025 - Total trip time less than 10 years - Minimum stay time of 60 days at each asteroid - Initial spacecraft mass of 2,000 kg - Thrust of 0.15 N and Isp of 3,000 s - Only Earth GAMs allowed (Rmin = 6,871 km) Preliminary results indicate that for mission objectives we can visit Apophis and any other 2 asteroids on this list or any other 3 asteroids listed. We have considered two spacecraft approaches to accomplish mission objectives: - Case 1: Chemical engine burn to the 1st target, and then solar electric to the 2nd and 3rd targets, or - Case 2: Solar electric propulsion to all 3 targets For both Cases, we assumed an instrument mass of up to 100 kg, power up to 100 W, and s/c bus pointing as good as 12 arc sec.Multi-NEO Mission Candidates

Comet Hunters: A Citizen Science Project to Search for Comets in the Main Asteroid Belt

NASA Astrophysics Data System (ADS)

Hsieh, Henry H.; Schwamb, Megan Elizabeth; Zhang, Zhi-Wei; Chen, Ying-Tung; Wang, Shiang-Yu; Lintott, Chris

2016-10-01

Fully automated detection of comets in wide-field surveys remains a challenge, as even highly successful comet-finding surveys like Pan-STARRS rely on a combination of both automated flagging algorithms and vetting by human eyes. To take advantage of the long-noted superiority of the human eye over computer algorithms in certain types of pattern recognition, particularly when dealing with a range of target morphologies of interest, we have created a citizen science website with the aim of allowing the general public to aid in the search for active asteroids, which are objects that occupy dynamically asteroidal orbits yet exhibit comet-like dust emission due to sublimation, impact disruption, rotational destabilization, or other effects. Located at comethunters.org, the Comet Hunters website was built using the Zooniverse Project Builder (https://www.zooniverse.org/lab), and displays images of known asteroids obtained either from archival data obtained between 1999 and 2014 by the Suprime-Cam wide-field imager mounted on the 8-m Subaru telescope on Mauna Kea in Hawaii, or more contemporary data obtained by the Hyper Suprime-Cam (HSC) wide-field imager also on the Subaru Telescope as part of the ongoing HSC Subaru Strategic Program (SSP) survey. By using observations from such a large-aperture telescope, most of which have never been searched for solar system objects, much less cometary ones, we expect that volunteers should be able to make genuinely scientifically significant discoveries, and also provide valuable insights into the potential and challenges of searching for comets in the LSST era. To date, over 13,000 registered volunteers have contributed 350,000 classifications. We will discuss the design and construction of the Comet Hunters website, and also discuss early results from the project.This work uses data generated via the Zooniverse.org platform, development of which was supported by a Global Impact Award from Google, and by the Alfred P. Sloan Foundation.The HSC SSP collaboration includes the astronomical communities of Japan and Taiwan, and Princeton University. Instrumentation and software for HSC were developed by NAOJ, Kavli IPMU, the University of Tokyo, KEK, ASIAA, and Princeton University.

The asteroid-comet continuum from laboratory and space analyses of comet samples and micrometeorites

NASA Astrophysics Data System (ADS)

Engrand, Cecile; Duprat, Jean; Bardin, Noemie; Dartois, Emmanuel; Leroux, Hugues; Quirico, Eric; Benzerara, Karim; Rémusat, Laurent; Dobrică, Elena; Delauche, Lucie; Bradley, John; Ishii, Hope; Hilchenbach, Martin; COSIMA Team

2015-08-01

Comets are probably the best archives of the nascent solar system, 4.5 Gyr ago, and their compositions reveal crucial clues on the structure and dynamics of the early protoplanetary disk. Anhydrous minerals (olivine and pyroxene) have been identified in cometary dust for a few decades. Surprisingly, samples from comet Wild2 returned by the Stardust mission in 2006 also contain high temperature mineral assemblages like chondrules and refractory inclusions, which are typical components of primitive meteorites (carbonaceous chondrites - CCs). A few Stardust samples have also preserved some organic matter of comet Wild 2 that share some similarities with CCs. Interplanetary dust falling on Earth originate from comets and asteroids in proportions to be further constrained. These cosmic dust particles mostly show similarities with CCs, which in turn only represent a few percent of meteorites recovered on Earth. At least two (rare) families of cosmic dust particles have shown strong evidences for a cometary origin: the chondritic porous interplanetary dust particles (CP-IDPs) collected in the terrestrial stratosphere by NASA, and the ultracarbonaceous Antarctic Micrometeorites (UCAMMs) collected from polar snow and ice by French and Japanese teams. The Rosetta mission currently carries dust analyzers capable of measuring dust flux, sizes, physical properties and compositions of dust particles from the Jupiter family comet 67P/Churyumov-Gerasimenko (COSIMA, GIADA, MIDAS), as well as gas analyzers (ROSINA, PTOLEMY, COSAC). A growing number of evidences highlights the existence of a continuum between asteroids and comets, already in the early history of the solar system. We will present the implications of the analyses of samples in the laboratory and in space to a better understanding of the early protoplanetary disk.

Earth-approaching asteroids: Populations, origin, and compositional types

NASA Technical Reports Server (NTRS)

Shoemaker, E. M.; Helin, E. F.

1978-01-01

Origin, physical properties, and discovery history of smaller asteroids are reviewed. They appear to link the main belt objects, namely the comets and meteorites. Physical observations suggest that a wide variety of compositional types are represented among the near-earth asteroids; the apparent rarity of carbonaceous objects is stated.

Observations of Spacecraft Targets, Unusual Asteroids, and Targets of Opportunity

NASA Technical Reports Server (NTRS)

Tholen, David J.

1998-01-01

Obtain physical and astrometric observations of: (1) spacecraft targets to support mission operations; (2) known asteroids with unusual orbits to help determine their origin; and (3) newly discovered minor planets (including both asteroids and comets) that represent a particular opportunity to add significant new knowledge of the Solar System.

Accurate Determination of Comet and Asteroid Orbits Leading to Collision With Earth

NASA Technical Reports Server (NTRS)

Roithmayr, Carlos M.; Kay-Bunnell, Linda; Mazanek, Daniel D.; Kumar, Renjith R.; Seywald, Hans; Hausman, Matthew A.

2005-01-01

Movements of the celestial bodies in our solar system inspired Isaac Newton to work out his profound laws of gravitation and motion; with one or two notable exceptions, all of those objects move as Newton said they would. But normally harmonious orbital motion is accompanied by the risk of collision, which can be cataclysmic. The Earth s moon is thought to have been produced by such an event, and we recently witnessed magnificent bombardments of Jupiter by several pieces of what was once Comet Shoemaker-Levy 9. Other comets or asteroids may have met the Earth with such violence that dinosaurs and other forms of life became extinct; it is this possibility that causes us to ask how the human species might avoid a similar catastrophe, and the answer requires a thorough understanding of orbital motion. The two red square flags with black square centers displayed are internationally recognized as a warning of an impending hurricane. Mariners and coastal residents who know the meaning of this symbol and the signs evident in the sky and ocean can act in advance to try to protect lives and property; someone who is unfamiliar with the warning signs or chooses to ignore them is in much greater jeopardy. Although collisions between Earth and large comets or asteroids occur much less frequently than landfall of a hurricane, it is imperative that we learn to identify the harbingers of such collisions by careful examination of an object s path. An accurate determination of the orbit of a comet or asteroid is necessary in order to know if, when, and where on the Earth s surface a collision will occur. Generally speaking, the longer the warning time, the better the chance of being able to plan and execute action to prevent a collision. The more accurate the determination of an orbit, the less likely such action will be wasted effort or, what is worse, an effort that increases rather than decreases the probability of a collision. Conditions necessary for a collision to occur are discussed, and warning times for long-period comets and near-Earth asteroids are presented.

Dynamics and Distribution of Interplanetary Dust

NASA Astrophysics Data System (ADS)

Ipatov, S. I.; Mather, J. C.

2005-08-01

We integrated the orbital evolution of 12,000 asteroidal, cometary, and trans-Neptunian dust particles, under the gravitational influence of planets, Poynting-Robertson drag, radiation pressure, and solar wind drag (Annals of the New York Academy of Sciences, v. 1017, 66-80, 2004; Advances in Space Research, in press, 2005). The orbital evolution of 30,000 Jupiter-family comets (JFCs) was also integrated (Annals of the New York Academy of Sciences, v. 1017, 46-65, 2004). For asteroidal and cometary particles, the values of the ratio β between the radiation pressure force and the gravitational force varied from <0.0004 to 0.4 (for silicates, such values correspond to particle diameters between >1000 and 1 microns). The considered cometary particles started from comets 2P, 10P, and 39P. The probability of a collision of an asteroidal or cometary dust particle with the Earth during a lifetime of the particle was maximum at diameter about 100 microns; this is in accordance with cratering records. Our different studies of migration of dust particles and small bodies testify that the fraction of cometary dust particles of the overall dust population inside Saturn's orbit is considerable and can be dominant: (1) Some JFCs can reach orbits entirely located inside Jupiter's orbit and remain in such orbits for millions of years. Such former comets could disintegrate during millions of years and produce a lot of mini-comets and dust. (2) The spatial density of migrating trans-Neptunian particles near Jupiter's orbit is smaller by a factor of several than that beyond Saturn's orbit. Only a small fraction of asteroidal particles can migrate outside Jupiter's orbit. Therefore cometary dust particles are needed to explain the observed constant spatial density of dust particles at 3-18 AU from the Sun. (3) Comparison of the velocities of zodiacal dust particles obtained in our runs with the observations of velocities of these particles made by Reynolds et al. (Ap.J., 2004, v. 612, 1206-1213) shows that only asteroidal dust particles cannot explain these observations, and particles produced by high-eccentricity comets (such as Comet Encke) are needed for such explanation. Several our recent papers are presented on astro-ph.

Physical observations of comets: Their composition, origin and evolution

NASA Technical Reports Server (NTRS)

Cochran, Anita L.; Barker, Edwin S.; Cochran, William D.

1991-01-01

The composition, origins, and evolution of comets were studied. The composition was studied using spectroscopic observations of primarily brighter comets at moderate and high resolution for the distribution of certain gases in the coma. The origins was addressed through an imaging search for the Kuiper belt of comets. The evolution was addressed by searching for a link between comets and asteroids using an imaging approach to search for an OH coma.

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.

Low-Gravity Centrifuge Facilities for Asteroid Lander and Material Processing and Manufacturing

NASA Astrophysics Data System (ADS)

Asphaug, E.; Thangavelautham, J.; Schwartz, S.

2018-02-01

We are developing space centrifuge research facilities for attaining low-gravity to micro-gravity geological environmental conditions representative of the environment on the surfaces of asteroids and comets.

Comet nucleus sample return mission

NASA Technical Reports Server (NTRS)

1983-01-01

A comet nucleus sample return mission in terms of its relevant science objectives, candidate mission concepts, key design/technology requirements, and programmatic issues is discussed. The primary objective was to collect a sample of undisturbed comet material from beneath the surface of an active comet and to preserve its chemical and, if possible, its physical integrity and return it to Earth in a minimally altered state. The secondary objectives are to: (1) characterize the comet to a level consistent with a rendezvous mission; (2) monitor the comet dynamics through perihelion and aphelion with a long lived lander; and (3) determine the subsurface properties of the nucleus in an area local to the sampled core. A set of candidate comets is discussed. The hazards which the spacecraft would encounter in the vicinity of the comet are also discussed. The encounter strategy, the sampling hardware, the thermal control of the pristine comet material during the return to Earth, and the flight performance of various spacecraft systems and the cost estimates of such a mission are presented.

Deep Interior: Probing the Structure of Primitive Bodies

NASA Astrophysics Data System (ADS)

Asphaug, Erik; Scheeres, Daniel; Safaeinili, Ali

Deep Interior is a mature Discovery-class mission concept focused on probing the geophysical behavior of primitive bodies, from the mechanics of their exterior materials to the structures of their interiors. Its theme is to discover how small bodies work - to learn the natural origin and evolution of asteroids, comets and other primitive bodies through radar reflection tomography and through detailed observations of the local and global effects of cratering. Learning the structure and mechanical response of asteroids and comets is also a precursor to resource utilization and hazardous asteroid mitigation. Overall the mission is aligned with NASA strategic sub-goal 3C, to advance scientific knowledge of the origin and history of the solar system ... and the hazards and resources present as humans explore space. Deep Interior deploys no complex landers or sub-spacecraft; the scientific instruments are a radar and a camera. A blast cratering experiments triggered by grenades leads to a low cost seismological investigation which complements the radar investigation. A desired addition is an imaging spectrometer. The science instruments are high heritage, as are the navigation techniques for orbiting and station-keeping. The mission conducts the following investigations at one or more asteroids: Radar Reflection Tomography (RRT). The first science phase is to operate a penetrating radar during each several-month rendezvous, deployed in reflection mode in the manner of ongoing radar investigations underway by Mars Express, Mars Reconnaissance Orbiter, and Kaguya. The RRT technique (Safaeinili et al., MAPS 2002) is analogous to performing a "CAT scan" from orbit: closely sampled radar echoes are processed to yield volumetric maps of mechanical and compositional boundaries, and to measure interior dielectric properties. Deep Interior utilizes a polar orbit (or station keeping) while the asteroid spins underneath; the result is to "peel the apple" with thousands of unique radar returns, providing global interior coverage. Camera images allow for the accurate reconstruction of spacecraft position at each radar acquisition. Radar flight heritage has been demonstrated by the MARSIS radar on Mars Express (Picardi et al., Science 2005; Plaut et al., Science 2007), the SHARAD radar onboard the Mars Reconnaissance Orbiter (Seu et al., JGR 2007), and the LRS radar onboard Kaguya (Ono et al, EPS 2007). The Mars radars have discovered detailed subsurface structure to km depths in a variety of terrains; early results from Kaguya demonstrate its ability to detect structure to km depths in basaltic materials on the Moon. A reflection radar deployed in orbit about a primitive body will enjoy significant simplifying benefits compared to using the same instrument for Mars or lunar radar science: (1) The proximity of operations leads to a much higher signal to noise, +30 dB or more. (2) The lack of an ionosphere makes for far simpler data modeling and analysis, compared with what is being required at Mars. (3) The body is globally illuminated during every data acquisition and since the final processing is a fully coherent focused processing based on all available observations, it will remove any "clutter" ambiguities. Laboratory measurements of dielectric properties for a suite of meteorite materials (Heggy et al., LPSC 2007) show that a 10 MHz radar can penetrate a chondritic asteroid up to 5 km diameter, and a 100 MHz radar can penetrate a chondritic asteroid up to 1 km diameter. The dielectric properties of different meteorite types can be discriminated, allowing radar to be used for interior compositional analysis. The primary trade is higher definition navigation for higher-resolution imaging, presuming that penetration requirements are met. It appears reliable that a SHARAD-type radar can image the global interior of a chondritic asteroid up to several km diameter. Radar imaging might leave a number of key questions unanswered, and to directly probe the mechanical behavior of an asteroid we conclude each rendezvous by observing one or more explosion cratering experiments. Cratering (CRT). Cratering is the primary mode of geologic evolution of asteroids, and meteoroid impacts can trigger outbursts on cometary nuclei. The process is important to study for its own sake, and a cratering experiment offers three additional science benefits: (1) final crater diameter and morphology indicates the mechanical behavior of regolith and other exterior materials; (2) cratering exposes the subsurface for analysis of interior materials; and (3) cratering might trigger global reverberations that can be detected using before-and-after image comparisons of toppled boulders and landslides. Small cratering events may be of global consequence on small asteroids (Asphaug, MAPS, in press) and thus a grenade of only a few kg is likely to send a detectable resurfacing reverberation spanning the asteroid. This experiment thus serves as a low cost proxy for primitive body seismology. Global seismic response is quantified using techniques that have been developed on Earth based on estimates for the dynamical acceleration of preciariously balanced rocks (Brune et al., JGR 2003). Ideally the mission would have two cratering charges per rendezvous target, differing by ˜2 orders of magnitude in yield, to bracket local to global response. Cratering and landslide physics will also be studied in this novel microgravity setting, for the purpose of establishing scaling rules and addressing fundamental problems of dense granular flow. Moreover, many cubic meters of ejected regolith are exposed for analysis of size distribution, clast shape, spectral heterogeneity, and dynamics. In the case that the asteroid is metastable (e.g. a rapid rotator), the small cratering event might trigger a global avalanche, in which case Deep Interior will observe the formation of transitory debris disks or small moons (e.g. Scheeres et al., Science 2007). Hazards to the spacecraft from these blast events have been computed from scaling laws for crater ejecta mass-velocity distributions, and are found to be minimal when the spacecraft is a few km away. This hazard drops to zero if the spacecraft is below the horizon of the blast, because dust is cleared out by the solar wind in about a day. Long term debris (moonlets and rings) are easily avoided since stable orbits are dynamically constrained (Scheeres et al., Icarus 1996). Unforeseen impacts with orbiting debris would occur at only a few cm/s.

Characterization of the Surface Properties of MUSES-C/Hayabusa Spacecraft Target Asteroid 25143 Itokawa (1998 SF36)

NASA Technical Reports Server (NTRS)

Lederer, S. M.; Domingue, D. L.; Vilas, F.; Abe, M.; Farnham, T. L.; Jarvis, K. S.; Lowry, S. C.; Ohba, Y.; Weissman, P. R.; French, L. M.

2004-01-01

Several spacecraft missions have recently targeted asteroids to study their morphologies and physical properties (e.g. Galileo, NEAR Shoemaker), and more are planned. MUSES-C is a Japanese mission designed to rendezvous with a near-Earth asteroid (NEA). The MUSES-C spacecraft, Hayabusa, was launched successfully in May 2003. It will rendezvous with its target asteroid in 2005, and return samples to the Earth in 2007. Its target, 25143 Itokawa (1998 SF36), made a close approach to the Earth in 2001. We collected an extensive ground-based database of broadband photometry obtained during this time, which maximized the phase angle coverage, to characterize this target in preparation for the mission. Our project was designed to capitalize on the broadband UBVRI photometric observations taken with a series of telescopes, instrumentation, and observers. Photometry and spectrophotometry of Itokawa were acquired at Lowell, McDonald, Steward, Palomar, Table Mountain and Kiso Observatories. The photometric data sets were combined to calculate Hapke model parameters of the surface material of Itokawa, and examine the solar-corrected broadband color characteristics of the asteroid. Broadband photometry of an object can be used to: (1) determine its colors and thereby contribute to the understanding of its surface composition and taxonomic class, and (2) infer global physical surface properties of the target body. We present both colors from UBVRI observations of the MUSES-C target Itokawa, and physical properties derived by applying a Hapke model to the broadband BVRI photometry.

A Cubesat Asteroid Mission: Propulsion Trade-offs

NASA Technical Reports Server (NTRS)

Landis, Geoffrey A.; Oleson, Steven R.; McGuire, Melissa L.; Bur, Michael J.; Burke, Laura M.; Fittje, James E.; Kohout, Lisa L.; Fincannon, James; Packard, Thomas W.; Martini, Michael C.

2014-01-01

A conceptual design was performed for a 6-U cubesat for a technology demonstration to be launched on the NASA Space Launch System (SLS) test launch EM-1, to be launched into a free-return translunar trajectory. The mission purpose was to demonstrate use of electric propulsion systems on a small satellite platform. The candidate objective chosen was a mission to visit a Near-Earth asteroid. Both asteroid fly-by and asteroid rendezvous missions were analyzed. Propulsion systems analyzed included cold-gas thruster systems, Hall and ion thrusters, incorporating either Xenon or Iodine propellant, and an electrospray thruster. The mission takes advantage of the ability of the SLS launch to place it into an initial trajectory of C3=0.

KSC-99pc49

NASA Image and Video Library

1999-01-11

In the Payload Hazardous Servicing Facility, workers look over the solar panels on the Stardust spacecraft that are deployed for lighting tests. Stardust is scheduled to be launched aboard a Boeing Delta II rocket from Launch Pad 17A, Cape Canaveral Air Station, on Feb. 6, 1999, for a rendezvous with the comet Wild 2 in January 2004. Stardust will use a substance called aerogel to capture comet particles flying off the nucleus of the comet, plus collect interstellar dust for later analysis. The collected samples will return to Earth in a sample return capsule to be jettisoned as it swings by Earth in January 2006

KSC-99pc43

NASA Image and Video Library

1999-01-11

In the Payload Hazardous Servicing Facility, workers adjust the solar panels of the Stardustspacecraft before performing lighting tests. Stardust is scheduled to be launched aboard a Boeing Delta II rocket from Launch Pad 17A, Cape Canaveral Air Station, on Feb. 6, 1999, for a rendezvous with the comet Wild 2 in January 2004. Stardust will use a substance called aerogel to capture comet particles flying off the nucleus of the comet, plus collect interstellar dust for later analysis. The collected samples will return to Earth in a sample return capsule to be jettisoned as it swings by Earth in January 2006

KSC-99pc38

NASA Image and Video Library

1999-01-11

Workers in the Payload Hazardous Servicing Facility deploy a solar panel on the Stardust spacecraft before performing lighting tests. Stardust is scheduled to be launched aboard a Boeing Delta II rocket from Launch Pad 17A, Cape Canaveral Air Station, on Feb. 6, 1999, for a rendezvous with the comet Wild 2 in January 2004. Stardust will use a substance called aerogel to capture comet particles flying off the nucleus of the comet, plus collect interstellar dust for later analysis. The collected samples will return to Earth in a sample return capsule to be jettisoned as it swings by Earth in January 2006

KSC-99pc41

NASA Image and Video Library

1999-01-11

In the Payload Hazardous Servicing Facility, a worker (left) conducts lighting tests on the fully extended solar panels of the Stardustspacecraft. Stardust is scheduled to be launched aboard a Boeing Delta II rocket from Launch Pad 17A, Cape Canaveral Air Station, on Feb. 6, 1999, for a rendezvous with the comet Wild 2 in January 2004. Stardust will use a substance called aerogel to capture comet particles flying off the nucleus of the comet, plus collect interstellar dust for later analysis. The collected samples will return to Earth in a sample return capsule to be jettisoned as it swings by Earth in January 2006

Changing Speed of Comets

ERIC Educational Resources Information Center

Follows, Mike

2003-01-01

It is shown that highly elliptical orbits, such as those of comets, can be explained well in terms of energy rather than forces. The principle of conservation of energy allows a comet's velocity to be calculated at aphelion and perihelion. An example asks students to calculate whether they can run fast enough to escape from a small asteroid.…

Ultralow-mass solar-array designs for Halley's comet rendezvous mission

NASA Technical Reports Server (NTRS)

Costogue, E. N.; Rayl, G.

1978-01-01

This paper describes the conceptual design study results of photovoltaic arrays capable of powering a Halley's comet rendezvous mission. This mission would be Shuttle-launched, employ a unique form of propulsion (ion drive) which requires high power levels for operation, and operate at distances between 0.6 and 4.5 AU. These requirements make it necessary to develop arrays with extremely high power-to-mass ratio (200 W/kg). In addition, the dual requirements of providing ion thruster power as well as housekeeping power leads to the development of unique methods for mode switching. Both planar and variable-concentrator-enhanced array concepts using ultrathin (50 micron) high-efficiency (up to 12.5%) silicon solar cells coupled with thin (75 micron) plastic encapsulants are considered. In order to satisfy the Shuttle launch environment it was necessary to provide novel methods of both storing and deploying these arrays.

Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer Planning (OSIRIS-REx)

NASA Technical Reports Server (NTRS)

Nakamura-Messenger, Keiko; Messenger, Scott; Keller, Lindsay; Righter, Kevin

2014-01-01

Scientists at ARES are preparing to curate and analyze samples from the first U.S. mission to return samples from an asteroid. The Origins-Spectral Interpretation- Resource Identification-Security-Regolith Explorer, or OSIRIS-REx, was selected by NASA as the third mission in its New Frontiers Program. The robotic spacecraft will launch in 2016 and rendezvous with the near-Earth asteroid Bennu, in 2020. A robotic arm will collect at least 60 grams of material from the surface of the asteroid to be returned to Earth in 2023 for worldwide distribution by the NASA Astromaterials Curation Facility at ARES.

Spectral Characterization of Analog Samples in Anticipation of OSIRIS-REx's Arrival at Bennu

NASA Technical Reports Server (NTRS)

Donaldson Hanna, K. L.; Schrader, D. L.; Bowles, N. E.; Clark, B. E.; Cloutis, E. A.; Connolly, H. C., Jr.; Hamilton, V. E.; Keller, L. P.; Lauretta, D. S.; Lim, L. F.;

Scientific rationale and strategies for a first comet mission: Report of the Comet Halley science working group

NASA Technical Reports Server (NTRS)

1977-01-01

The science objectives of a first comet mission are reviewed and related to what is known or can be expected to be learned in the near future from ground-based and near earth observations. A set of instruments and their science objectives are defined for a mission to Comet Halley during its 1985/86 apparition. The benefits from a fast flyby, a slow flyby, or a rendezvous mission and the relative impact of each on the instrument payload were assessed. The relative scientific value of encounters with the comet at distances from the sun ranging from 1 AU to 2.5 AU, including possible tradeoffs between flyby velocity and distance was considered. Pre- and post-perihelion encounters were likewise evaluated.

Environmental Perturbations Caused by the Impacts of Asteroids and Comets

NASA Technical Reports Server (NTRS)

Toon, Owen B.; Zahnle, Kevin; Morrison, David; Turco, Richard; Covey, Curt

1997-01-01

We review the major mechanisms proposed to cause extinctions at the Cretaceous-Tertiary geological boundary following an asteroid impact. We then discuss how the proposed extinction may relate to the impact of asteroids or comets in general. We discuss the limitations of these mechanisms in terms of the spatial scale that may be affected, and the time scale over which the effects may last. Our goal is to provide relatively simple prescriptions for evaluating the importance of colliding objects having a range of energies and compositions. We also identify the many uncertainties concerning the environmental effects of impacts. We conclude that, for impact energies below about 10(exp 4) Mts (megatons of TNT equivalent) - i.e., impact frequencies less than in 6 x 10(exp 4) yr, corresponding to comets and asteroids with diameters smaller than about 400 m and 650 m, respectively - blast damage, earthquakes, and fires should be important on a scale of 10(exp 4) or 10(exp 5) km (exp 2), which corresponds to the area damaged in many natural disasters of recent history. However, tsunami could be more damaging, flooding a kilometer of coastal plane over entire ocean basins. In the energy range of 10(exp 4) to 10 (exp 5) Mts (intervals up to 3 x 10(exp 5) yr; comets and asteroids with sizes up to 800 m and 1.5 km, respectively) water vapor injections and ozone loss become significant on the global scale. In the submicrometer dust injection fraction from the pulverized target material is much higher than is presently thought to be most likely, then dust injection could be important in this energy range.

Rosetta begins its 10-year journey to the origins of the Solar System

NASA Astrophysics Data System (ADS)

2004-03-01

Rosetta’s mission began at 08h17 CET (07h17 GMT) on 2 March when a European Ariane 5 launch vehicle liftered off from the Guiana Space Centre, Europe’s spaceport in Kourou, French Guiana. The launcher successfully placed its upper stage and payload into an eccentric coast orbit (200 x 4000 km). About two hours later, at 10h14 CET (09h14 GMT) the upper stage ignited its own engine to reach an escape velocity in order to leave the Earth’s gravity field and enter heliocentric orbit. The Rosetta probe was released about 18 minutes later. “After the recent success of Mars Express, Europe is now heading to deep space with another fantastic mission. We will have to be patient, as the rendezvous with the comet will not take place until ten years from now, but I think it’s worth the wait” said ESA’s Director General Jean-Jacques Dordain witnessing the launch from Kourou. ESA’s Operations Centre (ESOC) in Darmstadt, Germany, has established contact with the probe as it flies away from Earth at a relative speed of about 3.4 km/s. ESOC will be in charge of Rosetta operations and orbit determination throughout the mission. During the next eight months, the spacecraft’s onboard systems will be checked and its science payload will be commissioned. A 10-year odyssey Rosetta will be reactivated for planetary flybys, which will be used to modify its trajectory through gravity assist manoeuvres. During the trip, the probe could also observe one or more asteroids, observation of asteroids being one of the mission's secondary objectives. The first planetary encounter will be in March 2005, as Rosetta flies by the Earth for the first time. The gravity assist will boost Rosetta into an orbit that will take it to Mars two years later. During its close encounter with Mars in February 2007, Rosetta will approach to a distance of about 200 km and conduct science observations. This Martian flyby will be followed by another Earth flyby in November the same year. Both planetary encounters will increase the probe’s orbital energy and boost it well into the asteroid belt. A third and last flyby of the Earth in November 2009 will send Rosetta toward the orbit of comet Churyumov-Gerasimenko. Then, by mid-2011, when it is about 800 million km from the Sun, Rosetta will ignite its main engine for a major deep-space manoeuvre that will place it onto an interception trajectory with the comet, which will take nearly three years to be reached. Rosetta will be reactivated for good in January 2014, as it enters a six-month approach phase, closing in slowly on the nucleus of comet Churyumov-Gerasimenko. The comet will then still be far from the Sun and should not be active. Rendezvous with a comet Like comet 46P/Wirtanen, which was the planned target for Rosetta until its launch was postponed in early 2003, comet 67P/Churyumov-Gerasimenko is one of the periodic comets that were “trapped” in the inner Solar System after they came too close to Jupiter. This comet was discovered in September 1969 at the Almaty Astrophysical Institute in Kazakhstan. It was detected by astronomer Klim Churyumov, from the University of Kiev, Ukraine, on pictures taken by his colleague Svetlana Gerasimenko, from the Institute of Astrophysics of Dushanbe, Tajikistan. Rosetta will start accompanying the comet's nucleus in August 2014. It will then conduct detailed mapping of its surface and a landing site will be selected for Philae, its 100 kg lander. Philae will be dropped from an altitude of about 1 km and, due to the tiny gravity of the nucleus, it will touch down at walking speed. The lander will even have to anchor itself to the surface with two harpoons to avoid bouncing back. Philae is expected to operate from the surface for several weeks, sending back very high resolution pictures and as information about the upper crust of the nucleus. These data will be relayed to Earth by the orbiter. Rosetta will continue its observations of the comet’s nucleus for over a year, at least until December 2015, and will have a ringside seat to monitor the « awakening » of the comet’s activity as it comes closer to the Sun and reached its perihelion, in October 2015. Probing the comet The Rosetta probe was built for ESA by an industrial team of over 50 European companies led by EADS Astrium. It is a 3 tonne spacecraft with solar arrays spanning an impressive 32 metres. This is the first probe designed to travel beyond the orbit of Mars to rely on solar cells for its power supply. In addition to the Philae lander, Rosetta incorporates a 165 kg science payload consisting of 11 instruments developed in partnership by ESA member countries and by the the United States. Four of these instruments are dedicated to observation of the nucleus: the ALICE ultraviolet spectrometer, the OSIRIS high-resolution camera, the VIRTIS imaging spectrometer and the MIRO microwave radiometer/spectrometer. Three more instruments will study the composition of the nucleus and its emanations; the COSIMA and ROSINA spectrometers and the MIDAS microscope. The GIADA collector will analyse dusts in the vicinity of the nucleus while the RPC group of sensors will characterise the internal structure of the comet’s coma and its interaction with the solar wind. The last two instruments, CONSERT and RSI, will use radio waves, one to probe the internal structure of the nucleus and the other to determine the distribution of masses inside the nucleus and the structure of the coma. The Philae lander, developed under the leadership of Germany’s DLR aerospace research agency, carries 9 instruments provided by ESA member countries in partnership with the United States, Hungary and Russia. Among these, the ÇIVA/ROLIS set of cameras will provide panoramic and stereoscopic high-resolution views. The APXS, COSAC and Ptolemy instruments will analyse soil compounds. The SESAME seismometer will probe the surface to a depth of 2 m, while its characteristics will be studied by the MUPUS instrument with sensors on the anchoring harpoon. The ROMAP magnetometer and a second model of the CONSERT experiment will study the magnetic field and its interactions with the solar wind. The Rosetta Stone -unearthed in Egypt more than 200 years ago- gave XIXth-century Egyptologists the keys to decipher hieroglyphic writing and to rediscover three millennia of forgotten Egyptian history and culture. The in-depth study of a comet’s nucleus and asteroids by the Rosetta probe is expected to enable today’s science community to decipher the mystery of the origins of our Solar System and to better understand the mechanisms ruling the formation of planetary systems around other stars.

Comet 322P/SOHO 1: An Asteroid with the Smallest Perihelion Distance?

NASA Astrophysics Data System (ADS)

Knight, Matthew M.; Fitzsimmons, Alan; Kelley, Michael S. P.; Snodgrass, Colin

2016-05-01

We observed comet 322P/SOHO 1 (P/1999 R1) from the ground and with the Spitzer Space Telescope when it was between 2.2 and 1.2 au from the Sun. These are the first observations of any Solar and Heliospheric Observatory (SOHO)-discovered periodic comet by a non-solar observatory and allow us to investigate its behavior under typical cometary circumstances. 322P appeared inactive in all images. Its light curve suggests a rotation period of 2.8 ± 0.3 hr and has an amplitude ≳0.3 mag, implying a density of at least 1000 kg m-3, considerably higher than that of any known comet. It has average colors of {g}\\prime -{r}\\prime =0.52+/- 0.04 and {r}\\prime -{I}\\prime =0.03+/- 0.06. We converted these to Johnson colors and found that the V - R color is consistent with average cometary colors, but R - I is somewhat bluer; these colors are most similar to V- and Q-type asteroids. Modeling of the optical and IR photometry suggests it has a diameter of 150-320 m and a geometric albedo of 0.09-0.42, with diameter and albedo inversely related. Our upper limits to any undetected coma are still consistent with a sublimation lifetime shorter than the typical dynamical lifetimes for Jupiter-family comets. These results suggest that 322P may be of asteroidal origin and only active in the SOHO fields of view via processes different from the volatile-driven activity of traditional comets. If so, it has the smallest perihelion distance of any known asteroid. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programme 095.C-0853, with Lowell Observatory’s Discovery Channel Telescope, and with Spitzer Space Telescope under program 11104.

Determination of Eros Physical Parameters for Near Earth Asteroid Rendezvous Orbit Phase Navigation

NASA Technical Reports Server (NTRS)

Miller, J. K.; Antreasian, P. J.; Georgini, J.; Owen, W. M.; Williams, B. G.; Yeomans, D. K.

1995-01-01

Navigation of the orbit phase of the Near Earth steroid Rendezvous (NEAR) mission will re,quire determination of certain physical parameters describing the size, shape, gravity field, attitude and inertial properties of Eros. Prior to launch, little was known about Eros except for its orbit which could be determined with high precision from ground based telescope observations. Radar bounce and light curve data provided a rough estimate of Eros shape and a fairly good estimate of the pole, prime meridian and spin rate. However, the determination of the NEAR spacecraft orbit requires a high precision model of Eros's physical parameters and the ground based data provides only marginal a priori information. Eros is the principal source of perturbations of the spacecraft's trajectory and the principal source of data for determining the orbit. The initial orbit determination strategy is therefore concerned with developing a precise model of Eros. The original plan for Eros orbital operations was to execute a series of rendezvous burns beginning on December 20,1998 and insert into a close Eros orbit in January 1999. As a result of an unplanned termination of the rendezvous burn on December 20, 1998, the NEAR spacecraft continued on its high velocity approach trajectory and passed within 3900 km of Eros on December 23, 1998. The planned rendezvous burn was delayed until January 3, 1999 which resulted in the spacecraft being placed on a trajectory that slowly returns to Eros with a subsequent delay of close Eros orbital operations until February 2001. The flyby of Eros provided a brief glimpse and allowed for a crude estimate of the pole, prime meridian and mass of Eros. More importantly for navigation, orbit determination software was executed in the landmark tracking mode to determine the spacecraft orbit and a preliminary shape and landmark data base has been obtained. The flyby also provided an opportunity to test orbit determination operational procedures that will be used in February of 2001. The initial attitude and spin rate of Eros, as well as estimates of reference landmark locations, are obtained from images of the asteroid. These initial estimates are used as a priori values for a more precise refinement of these parameters by the orbit determination software which combines optical measurements with Doppler tracking data to obtain solutions for the required parameters. As the spacecraft is maneuvered; closer to the asteroid, estimates of spacecraft state, asteroid attitude, solar pressure, landmark locations and Eros physical parameters including mass, moments of inertia and gravity harmonics are determined with increasing precision. The determination of the elements of the inertia tensor of the asteroid is critical to spacecraft orbit determination and prediction of the asteroid attitude. The moments of inertia about the principal axes are also of scientific interest since they provide some insight into the internal mass distribution. Determination of the principal axes moments of inertia will depend on observing free precession in the asteroid's attitude dynamics. Gravity harmonics are in themselves of interest to science. When compared with the asteroid shape, some insight may be obtained into Eros' internal structure. The location of the center of mass derived from the first degree harmonic coefficients give a direct indication of overall mass distribution. The second degree harmonic coefficients relate to the radial distribution of mass. Higher degree harmonics may be compared with surface features to gain additional insight into mass distribution. In this paper, estimates of Eros physical parameters obtained from the December 23,1998 flyby will be presented. This new knowledge will be applied to simplification of Eros orbital operations in February of 2001. The resulting revision to the orbit determination strategy will also be discussed.

Comet deflection by directed energy: a finite element analysis

NASA Astrophysics Data System (ADS)

Madajian, Jonathan; Griswold, Janelle; Gandra, Anush; Hughes, Gary B.; Zhang, Qicheng; Rupert, Nic; Lubin, Philip

2016-09-01

Comets and Asteroids are viable threats to our planet; if these space rocks are smaller than 25 meters, they burn up in the atmosphere, but if they are wider than 25 meters they can cause damage to the impact area. Anything more than one to two kilometers can have worldwide effects, furthermore a mile-wide asteroid travelling at 30,000 miles per hour has the energy equal to a megaton bomb and is very likely to wipe out most of the life on Earth. Residents near Chelyabinsk, Russia experienced the detrimental effects of a collision with a Near-Earth Asteroid (NEA) on 15 February 2013 as a 20 m object penetrated the atmosphere above that city. The effective yield from this object was approximately 1/2 Megaton TNT equivalent (Mt), or that of a large strategic warhead. The 1908 Tunguska event, also over Russia, is estimated to have had a yield of approximately 15 Mt and had the potential to kill millions of people had it come down over a large city1. In the face of such danger a planetary defense system is necessary and this paper proposes a design for such a system. DE-STAR (Directed Energy System for Targeting of Asteroids and exploRation) is a phased array laser system that can be used to oblate, deflect and de-spin asteroids and comets.

Migration of Interplanetary Dust and Comets

NASA Astrophysics Data System (ADS)

Ipatov, S. I.; Mather, J. C.

Our studies of migration of interplanetary dust and comets were based on the results of integration of the orbital evolution of 15,000 dust particles and 30,000 Jupiter-family comets (JFCs) [1-3]. For asteroidal and cometary particles, the values of the ratio β between the radiation pressure force and the gravitational force varied from <0.0004 to 0.4. For silicates, such values correspond to particle diameters between >1000 and 1 microns. The probability of a collision of a dust particle started from an asteroid or JFC with the Earth during a lifetime of the particle was maximum at diameter d ˜100 microns. For particles started from asteroids and comet 10P, this maximum probability was ˜0.01. Different studies of migration of dust particles and small bodies testify that the fraction of cometary dust particles of the overall dust population inside Saturn's orbit is considerable and can be dominant: (1) Cometary dust particles produced both inside and outside Jupiter's orbit are needed to explain the observed constant number density of dust particles at 3-18 AU. The number density of migrating trans-Neptunian particles near Jupiter's orbit is smaller by a factor of several than that beyond Saturn's orbit. Only a small fraction of asteroidal particles can get outside Jupiter's orbit. (2) Some (less than 0.1%) JFCs can reach typical near-Earth object orbits and remain there for millions of years. Dynamical lifetimes of most of the former JFCs that have typical near-Earth object orbits are about 106 -109 yr, so during most of these times they were extinct comets. Such former comets could disintegrate and produce a lot of mini-comets and dust. (3) Comparison of the velocities of zodiacal dust particles (velocities of MgI line) based on the distributions of particles over their orbital elements obtained in our runs [3-4] with the velocities obtained at the WHAM observations shows that only asteroidal dust particles cannot explain these observations, and particles produced by comets, including high-eccentricity comets, are needed for such explanation. The fraction of particles started from Encke-type comets is not large (<0.15) in order to fit the observational distributions of particles over their distances from the Sun. Studies of velocities of MgI line and corresponding eccentricities and inclinations in our runs showed that the mean eccentricity of zodiacal dust particles is about 0.5. [1] Ipatov S.I. and Mather J.C. (2004) Annals of the New York Acad. of Sciences, 1017, 46- 65. [2] Ipatov S.I., Mather J.C., and Taylor P. (2004) Annals of the New York Acad. of Sciences, 1017, 66-80. [3] Ipatov S.I. and Mather J.C. (2006) Advances in Space Research, 37, 126-137. [4] Ipatov S.I. et al. (2006) 37th LPSC, #1471.

Advanced planning activity. [for interplanetary flight and space exploration

NASA Technical Reports Server (NTRS)

1974-01-01

Selected mission concepts for interplanetary exploration through 1985 were examined, including: (1) Jupiter orbiter performance characteristics; (2) solar electric propulsion missions to Mercury, Venus, Neptune, and Uranus; (3) space shuttle planetary missions; (4) Pioneer entry probes to Saturn and Uranus; (5) rendezvous with Comet Kohoutek and Comet Encke; (6) space tug capabilities; and (7) a Pioneer mission to Mars in 1979. Mission options, limitations, and performance predictions are assessed, along with probable configurational, boost, and propulsion requirements.

Positions of minor planets and Comet Panther (1980 u) obtained at the Chorzow Observatory

NASA Astrophysics Data System (ADS)

Wlodarczyk, I.

Photographic observations of 17 asteroids and Comet Panther were made between 1977 and 1982 with a 200/1000 mm photographic camera coupled to a 300/4500 mm refractor. The Turner method with the complete second-order polynomial was used to reduce the 16 x 16 cm ORWO ZU-2 plates that were obtained. The tabulated information for each asteroid and the comet include the number of the observation, the time of the observation in Universal Time, the topocentric position of the object referred to the mean epoch 1950.0, the dispersion in right ascension and declination, the duration of the exposure in minutes, and the symbol of the observer. Ten observers participated in the program.

The 1990 MB: The first Mars Trojan

NASA Technical Reports Server (NTRS)

Bowell, Edward

1991-01-01

Asteroid 1990 MB was discovered during the course of the Mars and Earth-crossing Asteroid and Comet Survey. An orbit based on a 9-day arc and the asteroid's location near Mars L5 longitude led to speculation that it might be in 1:1 resonance with Mars, analogous to the Trojan asteroids of Jupiter. Subsequent observations strengthened the possibility, and later calculations confirmed it. The most recent orbit shows that the asteroid's semimajor axis is very similar to that of Mars.

Virtual Observatory and Colitec Software: Modules, Features, Methods

NASA Astrophysics Data System (ADS)

Pohorelov, A. V.; Khlamov, S. V.; Savanevych, V. E.; Briukhovetskyi, A. B.; Vlasenko, V. P.

In this article we described complex processing system created by the CoLiTec project. This system includes features, user-friendly tools for processing control, results reviewing, integration with online catalogs and a lot of different computational modules that are based on the developed methods. Some of them are described in the article.The main directions of the CoLiTec software development are the Virtual Observatory, software for automated asteroids and comets detection and software for brightness equalization.The CoLiTec software is widely used in a number of observatories in the CIS. It has been used in about 700 000 observations, during which 1560 asteroids, including 5 NEO, 21 Trojan asteroids of Jupiter, 1 Centaur and four comets were discovered.

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.

Assessing Atmospheric Water Injection from Oceanic Impacts

NASA Technical Reports Server (NTRS)

Pierazzo, E.

2005-01-01

Collisions of asteroids and comets with the Earth s surface are rare events that punctuate the geologic record. Due to the vastness of Earth s oceans, oceanic impacts of asteroids or comets are expected to be about 4 times more frequent than land impacts. The resulting injections of oceanic water into the upper atmosphere can have important repercussions on Earth s climate and atmospheric circulation. However, the duration and overall effect of these large injections are still unconstrained. This work addresses atmospheric injections of large amounts of water in oceanic impacts.

Report of the Terrestrial Bodies Science Working Group. Volume 1: Executive summary. [Terrestrial planets, Galilean satellites, Comets, Asteroids, and the Moon

NASA Technical Reports Server (NTRS)

1977-01-01

Current knowledge of Mercury, Venus, Mars, the Moon, asteroids, comets, and the Galilean satellites were reviewed along with related NASA programs and available mission concepts. Exploration plans for the 1980 to 1990 period are outlined and recommendations made. Topics discussed include: scientific objectives and goals, exploration strategy and recommended mission plans, supporting research and technology, Earth-based and Earth-orbital investigations, data analysis and synthesis, analysis of extraterrestrial materials, broadening the science support base, and international cooperation.

A geological basis for the exploration of the planets: Introduction

NASA Technical Reports Server (NTRS)

Greeley, R.; Carr, M. H.

1976-01-01

The geological aspects of solar-system exploration were considered by first showing how geologic data are related to space science in general, and, second, by discussing the approach used in planetary geology. The origin, evolution, and distribution of matter condensed in the form of planets, satellites, comets, and asteroids were studied. Terrestrial planets, comets, and asteroids, and the solid satellites of the outer planets are discussed. Jupiter and Saturn, in particular, have satellites of prime importance. Geophysics, geochemistry, geodesy, cartography, and other disciplines concerned with the solid planets were all included.

The NEAR Multispectral Imager.

NASA Astrophysics Data System (ADS)

Hawkins, S. E., III

1998-06-01

Multispectral Imager, one of the primary instruments on the Near Earth Asteroid Rendezvous (NEAR) spacecraft, uses a five-element refractive optics telescope, an eight-position filter wheel, and a charge-coupled device detector to acquire images over its sensitive wavelength range of ≍400 - 1100 nm. The primary science objectives of the Multispectral Imager are to determine the morphology and composition of the surface of asteroid 433 Eros. The camera will have a critical role in navigating to the asteroid. Seven narrowband spectral filters have been selected to provide multicolor imaging for comparative studies with previous observations of asteroids in the same class as Eros. The eighth filter is broadband and will be used for optical navigation. An overview of the instrument is presented, and design parameters and tradeoffs are discussed.

KSC-99pc45

NASA Image and Video Library

1999-01-11

Bright white light (left) and blue light (upper right) appear on the solar panels of the Stardust spacecraft during lighting tests in the Payload Hazardous Servicing Facility. Stardust is scheduled to be launched aboard a Boeing Delta II rocket from Launch Pad 17A, Cape Canaveral Air Station, on Feb. 6, 1999, for a rendezvous with the comet Wild 2 in January 2004. Stardust will use a substance called aerogel to capture comet particles flying off the nucleus of the comet, plus collect interstellar dust for later analysis. The collected samples will return to Earth in a sample return capsule to be jettisoned as it swings by Earth in January 2006

Requirements and Capabilities for Planetary Missions: Mariner Encke Ballistic Flyby 1980

NASA Technical Reports Server (NTRS)

Ball, G. G.; Bird, T. H.

1975-01-01

This mission will provide a broad-based fast reconnaissance of comet Encke, building a data base for subsequent more detailed comet investigations, including rendezvous. After a 3 month flight, the spacecraft will encounter the comet at a nominal range of about 500 km. Flyby velocity will be 7 to 28 km/sec depending on choice of arrival data (0 to 35 days before Encke perihelion) and launch vehicle. The spacecraft will be similar to the MVM 73 spacecraft, with scan platform and 117 kbps encounter data rate, and designed to survive the thermal environment of 0.34 to 0.8 AU.

KSC-99pc48

NASA Image and Video Library

1999-01-11

In the Payload Hazardous Servicing Facility, workers get ready to rotate the Stardust spacecraft before deploying the solar panels (at left and right) for lighting tests. Stardust is scheduled to be launched aboard a Boeing Delta II rocket from Launch Pad 17A, Cape Canaveral Air Station, on Feb. 6, 1999, for a rendezvous with the comet Wild 2 in January 2004. Stardust will use a substance called aerogel to capture comet particles flying off the nucleus of the comet, plus collect interstellar dust for later analysis. The collected samples will return to Earth in a sample return capsule to be jettisoned as it swings by Earth in January 2006

KSC-99pc47

NASA Image and Video Library

1999-01-11

In the Payload Hazardous Servicing Facility, workers raise the Stardust spacecraft from its workstand to move it to another area for lighting tests on the solar panels. Stardust is scheduled to be launched aboard a Boeing Delta II rocket from Launch Pad 17A, Cape Canaveral Air Station, on Feb. 6, 1999, for a rendezvous with the comet Wild 2 in January 2004. Stardust will use a substance called aerogel to capture comet particles flying off the nucleus of the comet, plus collect interstellar dust for later analysis. The collected samples will return to Earth in a sample return capsule to be jettisoned as it swings by Earth in January 2006

KSC-99pc40

NASA Image and Video Library

1999-01-11

Workers in the Payload Hazardous Servicing Facility watch as the Stardust spacecraft is rotated and lowered before deploying the solar panels for lighting tests. Stardust is scheduled to be launched aboard a Boeing Delta II rocket from Launch Pad 17A, Cape Canaveral Air Station, on Feb. 6, 1999, for a rendezvous with the comet Wild 2 in January 2004. Stardust will use a substance called aerogel to capture comet particles flying off the nucleus of the comet, plus collect interstellar dust for later analysis. The collected samples will return to Earth in a sample return capsule (seen on top of the spacecraft) to be jettisoned as it swings by Earth in January 2006

KSC-99pc44

NASA Image and Video Library

1999-01-11

In the Payload Hazardous Servicing Facility, a worker looks over the solar panels of the Stardust spacecraft before it undergoes lighting tests. Stardust is scheduled to be launched aboard a Boeing Delta II rocket from Launch Pad 17A, Cape Canaveral Air Station, on Feb. 6, 1999, for a rendezvous with the comet Wild 2 in January 2004. Stardust will use a substance called aerogel to capture comet particles flying off the nucleus of the comet, plus collect interstellar dust for later analysis. The collected samples will return to Earth in a sample return capsule (its white cap is seen on the left) to be jettisoned as it swings by Earth in January 2006

STARDUST and HAYABUSA: Sample Return Missions to Small Bodies in the Solar System

NASA Technical Reports Server (NTRS)

Sandford, S. A.

2005-01-01

There are currently two active spacecraft missions designed to return samples to Earth from small bodies in our Solar System. STARDUST will return samples from the comet Wild 2, and HAYABUSA will return samples from the asteroid Itokawa. On January 3,2004, the STARDUST spacecraft made the closest ever flyby (236 km) of the nucleus of a comet - Comet Wild 2. During the flyby the spacecraft collected samples of dust from the coma of the comet. These samples will be returned to Earth on January 15,2006. After a brief preliminary examination to establish the nature of the returned samples, they will be made available to the general scientific community for study. The HAYABUSA spacecraft arrived at the Near Earth Asteroid Itokawa in September 2005 and is currently involved in taking remote sensing data from the asteroid. Several practice landings have been made and a sample collection landing will be made soon. The collected sample will be returned to Earth in June 2007. During my talk I will discuss the scientific goals of the STARDUST and HAYABUSA missions and provide an overview of their designs and flights to date. I will also show some of the exciting data returned by these spacecraft during their encounters with their target objects.

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.

Observation of asteroid 2013 TV135 supports my idea that a new impaction will come in 20 years

NASA Astrophysics Data System (ADS)

Cao, Dayong

2014-03-01

Asteroid 2013 TV135 who will impact in 2023 was newly discovered by Ukrainian astronomers in 2013. It supports my idea that a new impaction will come in 20 years. http://www.nasa.gov/mission_pages/asteroids/news/asteroid20131017.html, http://meetings.aps.org/link/BAPS.2011.DFD.LA.24, http://meetings.aps.org/link/BAPS.2012.APR.K1.78, http://meetings.aps.org/link/BAPS.2013.APR.S2.14. The Sun's companion-dark hole, which is made of dark matter seasonal took its dark comets belt, dark matter, dark lives, and the pressed asteroids belt to impact near our earth. These impactions and dark matter's killers caused seasonal extinctions and produced new species. By many dark comets and asteroids impacting, the dark impaction model is a high probability impaction model; the impaction would not change the orbit of the invisible dark hole, so that it could keep accurate periodicity impactions. With the space-time center, the dark hole system is a negative Einstein's model by ``mass-energy coordinate.'' Sun and Dark hole build up the balance system. Through studying the model, the rule of the impaction can be calculated. Avoid Earth Extinction Association.

Electromagnetic Scattering Analysis of Large Size Asteroids/Comets for Reflection/Transmission Tomography (RTT)

NASA Technical Reports Server (NTRS)

Deshpande, Manohar

2011-01-01

A precise knowledge of the interior structure of asteroids, comets, and Near Earth Objects (NEO) is important to assess the consequences of their impacts with the Earth and develop efficient mitigation strategies. Knowledge of their interior structure also provides opportunities for extraction of raw materials for future space activities. Low frequency radio sounding is often proposed for investigating interior structures of asteroids and NEOs. For designing and optimizing radio sounding instrument it is advantageous to have an accurate and efficient numerical simulation model of radio reflection and transmission through large size bodies of asteroid shapes. In this presentation we will present electromagnetic (EM) scattering analysis of electrically large size asteroids using (1) a weak form formulation and (2) also a more accurate hybrid finite element method/method of moments (FEM/MOM) to help estimate their internal structures. Assuming the internal structure with known electrical properties of a sample asteroid, we first develop its forward EM scattering model. From the knowledge of EM scattering as a function of frequency and look angle we will then present the inverse scattering procedure to extract its interior structure image. Validity of the inverse scattering procedure will be presented through few simulation examples.

Ground-based observation of near-Earth asteroids

NASA Technical Reports Server (NTRS)

Gaffey, Michael J.

1992-01-01

An increased ground-based observation program is an essential component of any serious attempt to assess the resource potential of near-Earth asteroids. A vigorous search and characterization program could lead to the discovery and description of about 400 to 500 near-Earth asteroids in the next 20 years. This program, in conjunction with meteorite studies, would provide the data base to ensure that the results of a small number of asteroid-rendezvous and sample-return missions could be extrapolated with confidence into a geological base map of the Aten, Apollo, and Amor asteroids. Ground-based spectral studies of nearly 30 members of the Aten/Apollo/Amor population provide good evidence that this class includes bodies composed of silicates, metal-silicates, and carbonaceous assemblages similar to those found in meteorites. The instruments that are being used or could be used to search for near-Earth asteroids are listed. Techniques useful in characterizing asteroids and the types of information obtainable using these techniques are listed.

Overview of the Mission Design Reference Trajectory for NASA's Asteroid Redirect Robotic Mission

NASA Technical Reports Server (NTRS)

Mcguire, Melissa L.; Strange, Nathan J.; Burke, Laura M.; McCarty, Steven L.; Lantoine, Gregory B.; Qu, Min; Shen, Haijun; Smith, David A.; Vavrina, Matthew A.

2017-01-01

The National Aeronautics and Space Administration's (NASA's) recently cancelled Asteroid Redirect Mission was proposed to rendezvous with and characterize a 100 m plus class near-Earth asteroid and provide the capability to capture and retrieve a boulder off of the surface of the asteroid and bring the asteroidal material back to cislunar space. Leveraging the best of NASA's science, technology, and human exploration efforts, this mission was originally conceived to support observation campaigns, advanced solar electric propulsion, and NASA's Space Launch System heavy-lift rocket and Orion crew vehicle. The asteroid characterization and capture portion of ARM was referred to as the Asteroid Redirect Robotic Mission (ARRM) and was focused on the robotic capture and then redirection of an asteroidal boulder mass from the reference target, asteroid 2008 EV5, into an orbit near the Moon, referred to as a Near Rectilinear Halo Orbit where astronauts would visit and study it. The purpose of this paper is to document the final reference trajectory of ARRM and the challenges and unique methods employed in the trajectory design of the mission.

Discovery: Near-Earth Asteroid Rendezvous (NEAR)

NASA Technical Reports Server (NTRS)

Veverka, Joseph

1992-01-01

The work carried out under this grant consisted of two parallel studies aimed at defining candidate missions for the initiation of the Discovery Program being considered by NASA's Solar System Exploration Division. The main study considered a Discover-class mission to a Near Earth Asteroid (NEA); the companion study considered a small telescope in Earth-orbit dedicated to ultra violet studies of solar system bodies. The results of these studies are summarized in two reports which are attached (Appendix 1 and Appendix 2).

A Study of the Effects of Faint Dust Comae on the Spectra of Asteroids

NASA Astrophysics Data System (ADS)

Rondón, E.; Carvano, J.; Lorenz-Martins, S.

2017-09-01

The presence of dust comae on asteroids and centaurs is a phenomenon that became accepted in the last decades and which challenges the traditional definitions of asteroids and comets. A possible way of improving the chances of discovery of Active Asteroids is to use large multi-colour surveys or catalogs, like SDSS Moving Object Catalog. In this work we analyze the effects of faint dust comae on asteroid spectra and then use it to investigate the effects that a faint dust comae would have over the spectrum, magnitude, and radial profile of asteroids.

Analysis of the orbit of the Centaur asteroid 2009 HW77

NASA Astrophysics Data System (ADS)

Wlodarczyk, I.; Cernis, K.; Eglitis, I.

2011-12-01

We present the time evolution of orbital elements of the Centaur asteroid 2009 HW77, discovered by KC and IE, forwards and backwards in time over a 10-Myr period. The dynamical behaviour is analysed using three software packages: the ORBFIT, the SWIFT and the MERCURY integrators. Changes in the orbital elements of 2009 HW77 clones are calculated using the classification of Horner et al. It is shown that close approaches to the giant planets significantly change the asteroid orbit. Our computations made with the SWIFT software and with the MERCURY software give similar results. The half-life is about 5 Myr in both the forward and backward integrations. Moreover, our computations suggest that the Centaur asteroid will be temporarily locked as a periodic asteroid connected with Jupiter with a Tisserand parameter smaller than 3. Hence it is dynamically similar to the Jupiter Family Comets. The mean duration in this state is about 82 kyr, but the behaviour and lifetime depend on whether capture occurs after a few hundred thousand years or a few hundred million years. Several clones of this dynamically interesting Centaur asteroid are temporarily locked up to four times as periodic asteroids connected with Jupiter, after which they are ejected from the Solar system. According to Bailey and Malhotra, asteroid 2009 HW77 may belong to the diffusing class of Centaurs, which can evolve into Jupiter Family Comets.

Impact as a general cause of extinction: A feasibility test

NASA Technical Reports Server (NTRS)

Raup, David M.

1988-01-01

Large body impact has been implicated as the possible cause of several extinction events. This is entirely plausible if one accepts two propositions: (1) that impacts of large comets and asteroids produce environmental effects severe enough to cause significant species extinctions and (2) that the estimates of comet and asteroid flux for the Phanerozoic are approximately correct. A resonable next step is to investigate the possibility that impact could be a significant factor in the broader Phanerozoic extinction record, not limited merely to a few events of mass extinction. Monte Carlo simulation experiments based on existing flux estimates and reasonable predictions of the relationship between bolide diameter and extinction are discussed. The simulation results raise the serious possibility that large body impact may be a more pervasive factor in extinction than has been assumed heretofore. At the very least, the experiments show that the comet and asteroid flux estimates combined with a reasonable kill curve produces a reasonable extinction record, complete with occasional mass extinctions and the irregular, lower intensity extinctions commonly called background extinction.

An Optimal Mitigation Strategy Against the Asteroid Impact Threat with Short Warning Time

NASA Technical Reports Server (NTRS)

Wie, Bong; Barbee, Brent; Pitz, Alan; Kaplinger, Brian; Hawkins, Matt; Winkler, Tim; Premaratne, Pavithra; Vardaxis, George; Lyzhoft, Joshua; Zimmerman, Ben

2015-01-01

To develop an innovative yet practically implementable mitigation technique for the most probable impact threat of an asteroid or comet with short warning time (i.e., when we don't have sufficient warning times for a deflection mission).

Ptolemy: in situ mass spectrometry during the Rosetta flyby of 21 Lutetia, and implications for future missions.

NASA Astrophysics Data System (ADS)

Andrews, D. J.; Morse, A. D.; Barber, S. J.; Leese, M. R.; Morgan, G. H.; Sheridan, S.; Wright, I. P.; Pillinger, C. T.

2011-10-01

Rosetta is the European Space Agency 'Planetary Cornerstone' mission intended to solve many of the unanswered questions surrounding the small bodies of the Solar System. Launched in March 2004 it is now over halfway through its decade long cruise, leading up to entering orbit around the nucleus of comet 67P/Churyumov-Gerasimenko in mid-2014. To date, this cruise has included three gravitational assist manoeuvres using Earth and one such manoeuvre using the gravity well of Mars. In addition, targeted flybys of two asteroids have returned a plethora of data to be compared with the comet observations to come. These flybys were of the 5.3 km diameter E-type asteroid 2867 Šteins on September 5th 2008, and a similar 3,162 km flyby of the 100 km diameter asteroid 21 Lutetia on July 10th 2010, the focus of this work. Recent ground based observations of the main belt asteroid 24 Themis have shown this body to have an organic-rich surface with exposed water ice [1]. It is also known that there at least four main belt comets - comets residing within the main belt, the prototype being 133P/Elst-Pizarro - and there are likely to be many more such bodies undergoing lower levels of cometary activity yet to be discovered [2]. The once clear-cut differentiation between volatile rich comets and volatile depleted asteroids has been somewhat eroded by these findings. Ptolemy is a miniature chemical analysis laboratory aboard the Rosetta lander 'Philae', and is intended to determine the chemical and isotopic composition of cometary material sourced from beneath, on and above the surface of the target comet. Samples are taken from the Sampler, Drill and Distribution system (SD2) and are then processed in a chemical preparation suite before delivery to a three channel gas chromatograph (GC). Elution products from the GC are passed to a quadrupole ion trap mass spectrometer for detection and quantitation [3]. As well as analysing solid samples, Ptolemy can passively adsorb coma material onto CarbosphereTM molecular sieve contained within one of the 26 SD2 sample ovens for later thermal release and analysis. Ptolemy can also make direct 'sniff' detections of the current spacecraft environment, bypassing the sample inlet and GC system, instead directly analyzing the inside of the mass spectrometer which is connected to space via a vent pipe. Based on the demonstrated instrument performance (a sensitivity of one ion count per 1x10-11 mbar for a particular mass), and knowing that the state of knowledge concerning the volatile composition and outgassing nature of main belt asteroids is only loosely constrained, it was decided to attempt to detect any extant, tenuous exosphere surrounding asteroid 21 Lutetia during the 2010 flyby opportunity. This body was thought to have both carbonaceous material and hydrated minerals on its surface - potential sources of outgassing - and therefore worthwhile of study [4].

Imaging spectrometer concepts for next-generation planetary missions

NASA Technical Reports Server (NTRS)

Herring, M.; Juergens, D. W.; Kupferman, P. N.; Vane, G.

1984-01-01

In recent years there has been an increasing interest in the imaging spectrometer concept, in which imaging is accomplished in multiple, contiguous spectral bands at typical intervals of 5 to 20 nm. There are two implementations of this concept under consideration for upcoming planetary missions. One is the scanning, or 'whisk-broom' approach, in which each picture element (pixel) of the scene is spectrally dispersed onto a linear array of detectors; the spatial information is provided by a scan mirror in combination with the vehicle motion. The second approach is the 'push-broom' imager, in which a line of pixels from the scene is spectrally dispersed onto a two-dimensional (area-array) detector. In this approach, the scan mirror is eliminated, but the optics and focal plane are more complex. This paper discusses the application of these emerging instrument concepts to the planetary program. Key issues are the trade-off between the two types of imaging spectrometer, the available data rate from a typical planetary mission, and the focal-plane cooling requirements. Specific straw-man conceptual designs for the Mars Geoscience/Climatology Orbiter (MGCO) and the Mariner Mark II Comet Rendezvous/Asteroid Flyby (CRAF) missions are discussed.

How well do you know The Earth, Asteroids, Comets?

NASA Astrophysics Data System (ADS)

Alexander, C. J.; Lopez, J.; Barkus, R. C.; Angrum, A.

2011-12-01

The U.S. Rosetta Project is the NASA contribution to the International Rosetta Mission, an ESA cornerstone mission. The mission will arrive at its target, comet 67 P/Churyumov-Gerasimenko, in 2014, and escort the comet around the Sun for the ensuing 17 months. Along the way, the mission has encountered two asteroids: 21/Lutetia, and 2867/Steins, and enjoyed gravity assists at Mars and several at the Earth. The challenge for outreach coordinators is to convey the excitement of the mission, the manner in which its experiments gather and interpret data, provide context for those interpretations, all in an engaging fashion, without heavy use of camera images -- the camera not being among the NASA contributed instruments. In other words, because the US Rosetta Project expects to present the data and results from: an ultraviolet spectrometer, a plasma instrument, and a microwave spectrometer, outreach is presented with the special challenges of engaging the public in data which at least visually is less accessible than that of camera images. The project has turned to online games, interactive simulations, animated cartoons, and virtual labs to provide a visually stimulating way to explain: how scientists determine the age of asteroids; the context of a timeline of Earth geologic history with which to understand the relative position of the ages of any given asteroid to some event on Earth; a model of the solar system that goes from our Sun to the next Star to understand the spatial distances covered by comets in their journey around the Sun; and a model of early solar system evolution in which to understand the possible scenarios of solar system evolution that comets can help us sort out. In this paper we will present these simulations, even if some of them remain in the beta-development phase at the time of the meeting itself. Work at the Jet Propulsion Laboratory, California Institute of Technology, was supported by NASA. Rosetta is a joint collaboration between NASA and the European Space Agency.

Spectral Characterization of Analog Samples in Anticipation of OSIRIS-REx's Arrival at Bennu

NASA Technical Reports Server (NTRS)

Donaldson Hanna, K. L.; Schrader, D. L.; Bowles, N. E.; Clark, B. E.; Cloutis, E. A.; Connolly, H. C., Jr.; Hamilton, V. E.; Keller, L. P.; Lauretta, D. S.; Lim, L. F.;

Laboratory measurements of dielectric properties of compact and granular materials, in relation with Rosetta mission.

NASA Astrophysics Data System (ADS)

Brouet, Y.; Levasseur-Regourd, A. C.; Encrenaz, P.; Gheudin, M.; Ciarletti, V.; Gulkis, S.; Jambon, A.; Ruffié, G.; Prigent, C.

2012-04-01

The European Rosetta spacecraft (s/c), launched in 2004, will be the first s/c to orbit a comet and place a lander module on its surface. In 2014, the s/c will rendezvous with the comet 67P/Churyumov-Gerasimenko and place the lander on its surface thereby allowing in situ and remote sensing of the comet nucleus. Two radio experiments, one passive (MIRO [1]) and one active (CONSERT [2]), are aboard the Rosetta s/c. MIRO, composed of two radiometers, with center band frequencies at 190 GHz and at 563 GHz to determine the brightness temperatures of the target surfaces and sub-surfaces, has already observed asteroids (2867) Steins [3] and (21) Lutetia [4]. CONSERT will investigate the deep interior of the nucleus using 90 MHz radio-waves transmitted from the orbiter through the nucleus and returned to the orbiter from the lander. To support interpretations of MIRO and CONSERT observations, a program of dielectric properties measurements is under development on a large range of frequencies encompassing those of the above-mentioned experiments. Several instruments for dielectric constant determination are available at IMS laboratory (Bordeaux, France): impedance analyzer, coaxial sensor, resonant cavities (measuring respectively at 100 MHz, 0.5-6 GHz, 1.2-13.4 GHz). Millimeter benches are available at both IMS and LERMA laboratories (measuring respectively at 30-110 GHz and 70-230 GHz). Taking into account the possible presence of regolith layers on the surface of asteroids or nuclei and the very low density of cometary nuclei [5], the dependence of the dielectric constant on the structure and porosity of given granular materials needs also to be investigated (while the thermal and hygrometric conditions are carefully monitored). We have already reported measurements obtained on various meteorites, possibly representative of some asteroid surfaces [6, 7]. We will also report systematic measurements obtained on a large sample of pyroclastic deposits from Etna, providing different sizes distributions (i.e. surface to volume ratios), and possibly porosities. Dielectric constant determination at 190 GHz typically suggests that the real part of dielectric constant slowly increases with grain size: 2.86 ± 0.06, 2.96 ± 0.02 and 3.13 ± 0.05 for sizes respectively lower than 50 µm, between 50 and 160 µm and between 160 and 355 µm. Additional series of measurements on compact and granular samples of meteoritic analogues, such as carbonaceous chondrites are also to take place. [1] Gulkis et al. , Space Sci. Rev., 128, 561-597, 2007. [2] Kofman et al. , Space Sci. Rev., 128, 413-432, 2007. [3] Gulkis et al. , Space. Sci. Rev., 58, 1077-1087, 2010. [4] Gulkis et al. , Space. Sci. Rev., doi: 10.1016/j.pss.2011.12.004, 2011. [5] Levasseur-Regourd et al. , Planet. Space Sci., 57, 221-228, 2009. [6] McFadden et al., 40th LPSC, 2887, 2009. [7] Brouet el al. , EPSC-DPS Joint Meeting, p. 1083, 2011.

Simulation of the Interactions Between Gamma-Rays and Detectors Using BSIMUL

NASA Technical Reports Server (NTRS)

Haywood, S. E.; Rester, A. C., Jr.

1996-01-01

Progress made during 1995 on the Monte-Carlo gamma-ray spectrum simulation program BSIMUL is discussed. Several features have been added, including the ability to model shield that are tapered cylinders. Several simulations were made on the Near Earth Asteroid Rendezvous detector.

Round-trip missions to low delta-V asteroids and implications for material retrieval

NASA Technical Reports Server (NTRS)

Bender, D. F.; Dunbar, R. S.; Ross, D. J.

1979-01-01

Low-delta-V asteroids are to be found among those which have perihelia near 1 AU. From the 50 known asteroids with perihelia less than 1.5 AU, 10 candidates for asteroid retrieval missions were selected on the basis of low eccentricity and inclination. To estimate the ranges of orbital elements for which capture in earth orbit may be feasible, a survey was made of 180 deg transfer from a set of orbits having elements near those of the earth to the earth. For 2 of the 10 low-delta-V asteroids and for an additional one with elements more earth-like than any yet known, direct ballistic round trips in the 1980's were computed. A stay time of several months at the asteroid was used. The results show that the total delta V, including that for rendezvous with earth upon return, for the known asteroids is above 14 km/sec. But if asteroids are found similar to the strawman considered, the total delta V could be as low as 10 km/sec.

Data base on physical observations of near-Earth asteroids and establishment of a network to coordinate observations of newly discovered near-Earth asteroids

NASA Technical Reports Server (NTRS)

Davis, D. R.; Chapman, C. R.; Campins, H.

1990-01-01

This program consists of two tasks: (1) development of a data base of physical observations of near-earth asteroids and establishment of a network to coordinate observations of newly discovered earth-approaching asteroids; and (2) a simulation of the surface of low-activity comets. Significant progress was made on task one and, and task two was completed during the period covered by this progress report.

Ultraviolet Characterization of Comet and Asteroid Surfaces as Observed by the Rosetta Alice Instrument (Invited)

NASA Astrophysics Data System (ADS)

Feaga, L. M.; Holt, C. E.; Steffl, A.; Stern, S. A.; Bertaux, J. L.; Parker, J. W.; A'Hearn, M. F.; Feldman, P.; Keeney, B. A.; Knight, M. M.; Noonan, J.; Vervack, R. J., Jr.; Weaver, H. A., Jr.

2017-12-01

In 2016, Alice, NASA's lightweight and low-power far-ultraviolet (FUV) imaging spectrograph onboard ESA's comet-orbiting spacecraft Rosetta, completed a 2-year characterization of 67P/Churyumov-Gerasimenko (C-G), a bi-lobed Jupiter family comet with extreme seasons and diverse surface features. In addition to coma studies, Alice monitored the sunlit surface of C-G from 700-2050 Å to establish the FUV bidirectional reflectance properties and albedo of the surface, determine homogeneity, correlate spectral features with morphological regions, and infer the compositional makeup of the comet. The heliocentric distance coverage (3.7 AU from the Sun, through perihelion at 1.24 AU, and back out to 3.8 AU) over a period of 2 years and spatial resolution of the Alice data (e.g., 30 m by 150 m at the comet from a spacecraft distance of 30 km) resulted in the first resolved observations of a cometary nucleus in the FUV throughout much of its orbit. Upon arrival in 2014, initial characteristics and properties of the surface were derived for the northern hemisphere, revealing a dark, homogeneous, and blue-sloped surface in the FUV with an average geometric albedo of 5% at 1475 Å, consistent with a homogeneous layer of dust covering that hemisphere and similar to nucleus properties derived for this and other comets in the visible. Now, with a fully calibrated dataset, properties of the southern and northern hemispheres, before and after perihelion, have been quantified and preliminarily show minimal change in the comet's surface in the FUV through the apparition. Analyses are ongoing and we will highlight any detected variability. En-route to C-G, Alice made history during the flybys of asteroid (2867) Steins and (21) Lutetia obtaining the first global FUV reflectivity measurement and acquiring spatially resolved observations of an asteroid surface, respectively. The asteroid properties will be compared to those derived for C-G to demonstrate commonalities across small bodies in our solar system. Rosetta is an ESA mission with contributions from its member states and NASA. The Alice team acknowledges continuing support from NASA's Jet Propulsion Laboratory through contract 1336850 to the Southwest Research Institute (SwRI). This work was supported by a subcontract from SwRI to the University of Maryland.

Voyager 2: Rendezvous with Saturn - America celebrates its space flight at the JPL

NASA Astrophysics Data System (ADS)

Thiele, S.

1981-11-01

Impressions of a German scientist invited to the Jet Propulsion Laboratory during the time of the rendezvous of Voyager 2 with Saturn are presented. During the period from the 21st to the 28th of August 1981, Voyager 2 transmitted data concerning Saturn and its satellites to earth. The received information, including photographs and measurement results, were made available at the JPL to approximately 100 scientists and a few hundred reporters. The future of planetary research is briefly discussed, and attention is given to a space mission for the study of the comet Halley in 1986.

The Ion Propulsion System on NASA's Space Technology 4/Champollion Comet Rendezvous Mission

NASA Technical Reports Server (NTRS)

Brophy, John R.; Garner, Charles E.; Weiss, Jeffery M.

1999-01-01

The ST4/Champollion mission is designed to rendezvous with and land on the comet Tempel 1 and return data from the first-ever sampling of a comet surface. Ion propulsion is an enabling technology for this mission. The ion propulsion system on ST4 consists of three ion engines each essentially identical to the single engine that flew on the DS1 spacecraft. The ST4 propulsion system will operate at a maximum input power of 7.5 kW (3.4 times greater than that demonstrated on DS1), will produce a maximum thrust of 276 mN, and will provide a total (Delta)V of 11.4 km/s. To accomplish this the propulsion system will carry 385 kg of xenon. All three engines will be operated simultaneously for the first 168 days of the mission. The nominal mission requires that each engine be capable of processing 118 kg. If one engine fails after 168 days, the remaining two engines can perform the mission, but must be capable of processing 160 kg of xenon, or twice the original thruster design requirement. Detailed analyses of the thruster wear-out failure modes coupled with experience from long-duration engine tests indicate that the thrusters have a high probability of meeting the 160-kg throughput requirement.

JPL-20170515-NEOWISf-0001-Three Years of NEOWISE Survey Data

NASA Image and Video Library

2017-06-05

NASA's asteroid hunting NEOWISE survey uses infrared to detect and characterize asteroids and comets. Animation shows the 114 near-Earth objects and 693 other objects characterized by the mission since the WISE mission (decommissioned in February 2011) was recommissioned as NEOWISE in December 2013.

Space debris, asteroids and satellite orbits; Proceedings of the Fourth and Thirteenth Workshops, Graz, Austria, June 25-July 7, 1984

NASA Technical Reports Server (NTRS)

Kessler, D. J.; Gruen, E.; Sehnal, L.

1985-01-01

The workshops covered a variety of topics relevant to the identification, characterization and monitoring of near-earth solar system debris. Attention was given to man-made and naturally occurring microparticles, their hazards to present and future spacecraft, and ground- and space-based techniques for tracking both large and small debris. The studies are extended to solid fuel particulates in circular space. Asteroid rendezvous missions are discussed, including propulsion and instrumentation options, the possibility of encountering asteroids during Hohman transfer flights to Venus and/or Mars, and the benefits of multiple encounters by one spacecraft. Finally, equipment and analytical models for generating precise satellite orbits are reviewed.

Search for Activity in Comet-Asteroid Transition Object 107P/Wilson-Harrington

NASA Astrophysics Data System (ADS)

Khayat, Alain; Meech, K.; Pittichova, J.; Schorghofer, N.; Yang, B.; Sonnett, S.; Riesen, T.; Kleyna, J.; Kaluna, H.; Keane, J.

2010-10-01

Comet-asteroid transition object 107P/Wilson-Harrington was observed near its October 22, 2009 perihelion passage to search for activity. No activity was detected. Consequently, we place limits on possible dust production of 0.013 kg/s at 1.23 AU. Furthermore, the data was not sufficient to constrain a rotation period; however, it is clear that the rotation period is > 4hr. Our data is consistent with the observations of others (6.1 hr). Phase function fitting yielded a value of the phase coefficient beta= 0.0406 ± .0001 mag/deg, similar to C-type asteroids that have a linear phase curve at large phase angles. Thermal models for 107P/Wilson-Harrington show that the average loss rate of exposed crystalline ice at zero latitude is in the order of 0.3 meters/year. The derived high loss rate suggests that 107P/Wilson-Harrington is deprived of surface ice. Our observations and analysis confirm earlier findings that 107P/Wilson-Harrington is an example of the very few such objects discovered so far. Such study we made is a critical next step in understanding the life of dormant comets, and a window into the evolutionary end states of the lives of comets that become extinct. This work has been supported in part by AST-0807521 from the National Science Foundation.

The potentially hazardous asteroid 2007CA19 as the parent of the η-Virginids meteoroid stream

NASA Astrophysics Data System (ADS)

Babadzhanov, P. B.; Kokhirova, G. I.; Obrubov, Yu. V.

2015-07-01

The orbit of the potentially hazardous near-Earth asteroid 2007CA19 is classified as comet-like according to the Tisserand parameter with a value of Tj = 2.8, therefore the object can be empirically considered as an extinct or dormant Jupiter-family comet. If 2007CA19 is really a former comet, it could have formed a meteoroid stream in the past in the period of its cometary activity. Investigation of the asteroid's orbital evolution shows that 2007CA19 is a quadruple-crosser of the Earth's orbit. Consequently, the meteoroid stream that is supposedly associated with the object can produce four meteor showers if, as expected, the perihelia arguments of the meteoroids are very distributed over the orbit. Theoretical radiants of the predicted showers were calculated using elements of the 2007CA19 osculating orbit that correspond to the positions of intersections with the Earth's orbit. A search for the predicted night-time showers has shown that the Northern and Southern η-Virginids can be associated to 2007CA19. Using the MOID IAU database, we identify two other daytime showers that can be associated with this asteroid. Thus, we confirm that 2007CA19 has an associated meteoroid stream that produces four active meteor showers in the Earth's atmosphere. This relationship supports the dynamical classification of the object and also points to the possibility of its cometary origin.

Migration of small bodies and dust to the terrestrial planets

NASA Astrophysics Data System (ADS)

Ipatov, Sergei I.; Mather, John C.

2005-02-01

We integrated the orbital evolution of 30,000 Jupiter-family comets, 1300 resonant asteroids, and 7000 asteroidal, trans-Neptunian, and cometary dust particles. For initial orbital elements of bodies close to those of Comets 2P, 10P, 44P, and 113P, a few objects got Earth-crossing orbits with semi-major axes a<2 AU and moved in such orbits for more than 1 Myr (up to tens or even hundreds of Myrs). Three objects (from 2P and 10P runs) even got inner-Earth orbits (with aphelion distance Q<0.983 AU) and Aten orbits for Myrs. Our results show that the trans-Neptunian belt can provide a significant portion of near-Earth objects, or the number of trans-Neptunian objects migrating inside the solar system can be smaller than it was earlier considered, or most of 1-km former trans-Neptunian objects that had got near-Earth object orbits for millions of years disintegrated into mini-comets and dust during a smaller part of their dynamical lifetimes. The probability of a collision of an asteroidal or cometary particle during its lifetime with the Earth was maximum at diameter d˜ 100 mum. At d<10 mum such probability for trans-Neptunian particles was less than that for asteroidal particles by less than an order of magnitude, so the fraction of trans-Neptunian particles with such diameter near Earth can be considerable.

Near-Earth Asteroid Tracking (NEAT): First Year Results

NASA Astrophysics Data System (ADS)

Helin, E. F.; Rabinowitz, D. L.; Pravdo, S. H.; Lawrence, K. J.

1997-07-01

The successful detection of Near-Earth Asteroids (NEAs) has been demonstrated by the Near-Earth Asteroid Tracking (NEAT) program at the Jet Propulsion Laboratory during its first year of operation. The NEAT CCD camera system is installed on the U. S. Air Force 1-m GEODSS telescope in Maui. Using state-of-the-art software and hardware, the system initiates nightly transmitted observing script from JPL, moves the telescopes for successive exposures of the selected fields, detects moving objects as faint as V=20.5 in 40 s exposures, determines their astrometric positions, and downloads the data for review at JPL in the morning. The NEAT system is detecting NEAs larger than 200m, comets, and other unique objects at a rate competitive with current operating systems, and bright enough for important physical studies on moderate-sized telescopes. NEAT has detected over 10,000 asteroids over a wide range of magnitudes, demonstrating the excellent capability of the NEAT system. Fifty-five percent of the detections are new objects and over 900 of them have been followed on a second night to receive designation from the Minor Planet Center. 14 NEAs (9 Amors, 4 Apollos, and 1 Aten) have been discovered since March 1996. Also, 2 long period comets and 1996 PW, an asteroidal object with an orbit of a long-period comet, with an eccentricity of 0.992 and orbital period of 5900 years. Program discoveries will be reviewed along with analysis of results pertaining to the discovery efficiency, distribution on the sky, range of orbits and magnitudes. Related abstract: Lawrence, K., et al., 1997 DPS

Exo-comet Detection in Debris Disks Around Young A-type Stars

NASA Astrophysics Data System (ADS)

Welsh, Barry; Montgomery, S. L.

2013-01-01

We present details of the successful search for comet-like bodies (i.e. exo-comets) in orbit around several nearby stars. These objects have been found in young stellar systems that are in the transitional stage of evolution between possession of a gaseous protoplanetary disk to that of a dust-rich debris disk. During this period it is thought that large planetesimals of ~ 1000 km diameter may cause dynamical perturbations in the population of smaller bodies (such as asteroids and comets), such that they are sent on highly eccentric orbits towards their parent star resulting in the liberation of large amounts of evaporating gas and dust. By observing the varying spectral absorption signature of the CaII K-line at 3933Å due to this liberated gas, we have been able to track the trajectory of these exo-comets over a time-frame of several nights as they approach (and sometimes pass around) the central star. The youngest debris disks (1 - 50 Myr) are thought to represent the last stage in the formation of planetary systems and they may resemble our solar system’s own debris disk at the time of the Late Heavy Bombardment when the terrestrial worlds were subject to frequent collisions with asteroids and comets. Collisions with water-rich comets from the outer regions of our solar system may have delivered water to thee Earth’s oceans.

Discovery of Main-belt Comet P/2006 VW139 by Pan-STARRS1

NASA Astrophysics Data System (ADS)

Hsieh, Henry H.; Yang, Bin; Haghighipour, Nader; Kaluna, Heather M.; Fitzsimmons, Alan; Denneau, Larry; Novaković, Bojan; Jedicke, Robert; Wainscoat, Richard J.; Armstrong, James D.; Duddy, Samuel R.; Lowry, Stephen C.; Trujillo, Chadwick A.; Micheli, Marco; Keane, Jacqueline V.; Urban, Laurie; Riesen, Timm; Meech, Karen J.; Abe, Shinsuke; Cheng, Yu-Chi; Chen, Wen-Ping; Granvik, Mikael; Grav, Tommy; Ip, Wing-Huen; Kinoshita, Daisuke; Kleyna, Jan; Lacerda, Pedro; Lister, Tim; Milani, Andrea; Tholen, David J.; Vereš, Peter; Lisse, Carey M.; Kelley, Michael S.; Fernández, Yanga R.; Bhatt, Bhuwan C.; Sahu, Devendra K.; Kaiser, Nick; Chambers, K. C.; Hodapp, Klaus W.; Magnier, Eugene A.; Price, Paul A.; Tonry, John L.

2012-03-01

The main-belt asteroid (300163) 2006 VW139 (later designated P/2006 VW139) was discovered to exhibit comet-like activity by the Pan-STARRS1 (PS1) survey telescope using automated point-spread-function analyses performed by PS1's Moving Object Processing System. Deep follow-up observations show both a short (~10'') antisolar dust tail and a longer (~60'') dust trail aligned with the object's orbit plane, similar to the morphology observed for another main-belt comet (MBC), P/2010 R2 (La Sagra), and other well-established comets, implying the action of a long-lived, sublimation-driven emission event. Photometry showing the brightness of the near-nucleus coma remaining constant over ~30 days provides further evidence for this object's cometary nature, suggesting it is in fact an MBC, and not a disrupted asteroid. A spectroscopic search for CN emission was unsuccessful, though we find an upper limit CN production rate of Q CN < 1.3 × 1024 mol s-1, from which we infer a water production rate of Q_H_2O<10^{26} mol s-1. We also find an approximately linear optical spectral slope of 7.2%/1000 Å, similar to other cometary dust comae. Numerical simulations indicate that P/2006 VW139 is dynamically stable for >100 Myr, while a search for a potential asteroid family around the object reveals a cluster of 24 asteroids within a cutoff distance of 68 m s-1. At 70 m s-1, this cluster merges with the Themis family, suggesting that it could be similar to the Beagle family to which another MBC, 133P/Elst-Pizarro, belongs.

DASTCOM5: A Portable and Current Database of Asteroid and Comet Orbit Solutions

NASA Astrophysics Data System (ADS)

Giorgini, Jon D.; Chamberlin, Alan B.

2014-11-01

A portable direct-access database containing all NASA/JPL asteroid and comet orbit solutions, with the software to access it, is available for download (ftp://ssd.jpl.nasa.gov/pub/xfr/dastcom5.zip; unzip -ao dastcom5.zip). DASTCOM5 contains the latest heliocentric IAU76/J2000 ecliptic osculating orbital elements for all known asteroids and comets as determined by a least-squares best-fit to ground-based optical, spacecraft, and radar astrometric measurements. Other physical, dynamical, and covariance parameters are included when known. A total of 142 parameters per object are supported within DASTCOM5. This information is suitable for initializing high-precision numerical integrations, assessing orbit geometry, computing trajectory uncertainties, visual magnitude, and summarizing physical characteristics of the body. The DASTCOM5 distribution is updated as often as hourly to include newly discovered objects or orbit solution updates. It includes an ASCII index of objects that supports look-ups based on name, current or past designation, SPK ID, MPC packed-designations, or record number. DASTCOM5 is the database used by the NASA/JPL Horizons ephemeris system. It is a subset exported from a larger MySQL-based relational Small-Body Database ("SBDB") maintained at JPL. The DASTCOM5 distribution is intended for programmers comfortable with UNIX/LINUX/MacOSX command-line usage who need to develop stand-alone applications. The goal of the implementation is to provide small, fast, portable, and flexibly programmatic access to JPL comet and asteroid orbit solutions. The supplied software library, examples, and application programs have been verified under gfortran, Lahey, Intel, and Sun 32/64-bit Linux/UNIX FORTRAN compilers. A command-line tool ("dxlook") is provided to enable database access from shell or script environments.

DISCOVERY OF MAIN-BELT COMET P/2006 VW{sub 139} BY Pan-STARRS1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hsieh, Henry H.; Yang Bin; Haghighipour, Nader

2012-03-20

The main-belt asteroid (300163) 2006 VW{sub 139} (later designated P/2006 VW{sub 139}) was discovered to exhibit comet-like activity by the Pan-STARRS1 (PS1) survey telescope using automated point-spread-function analyses performed by PS1's Moving Object Processing System. Deep follow-up observations show both a short ({approx}10'') antisolar dust tail and a longer ({approx}60'') dust trail aligned with the object's orbit plane, similar to the morphology observed for another main-belt comet (MBC), P/2010 R2 (La Sagra), and other well-established comets, implying the action of a long-lived, sublimation-driven emission event. Photometry showing the brightness of the near-nucleus coma remaining constant over {approx}30 days provides furthermore » evidence for this object's cometary nature, suggesting it is in fact an MBC, and not a disrupted asteroid. A spectroscopic search for CN emission was unsuccessful, though we find an upper limit CN production rate of Q{sub CN} < 1.3 Multiplication-Sign 10{sup 24} mol s{sup -1}, from which we infer a water production rate of Q{sub H{sub 2O}}<10{sup 26} mol s{sup -1}. We also find an approximately linear optical spectral slope of 7.2%/1000 A, similar to other cometary dust comae. Numerical simulations indicate that P/2006 VW{sub 139} is dynamically stable for >100 Myr, while a search for a potential asteroid family around the object reveals a cluster of 24 asteroids within a cutoff distance of 68 m s{sup -1}. At 70 m s{sup -1}, this cluster merges with the Themis family, suggesting that it could be similar to the Beagle family to which another MBC, 133P/Elst-Pizarro, belongs.« less

Search for Water in Outer Main Belt Based on AKARI Asteroid Catalog

NASA Astrophysics Data System (ADS)

Usui, Fumihiko

2012-06-01

We propose a program to search water ice on the surface of asteroids in the outer main belt regions, which have high albedo measured with AKARI. The distribution of water in the main belt provides important information to understanding of the formation and evolution of the solar system, because water is a good indicator of temperature in the early solar nebula. The existence of water ice is a hot topic in the solar system studies today. Water ice is recently found in the outer region of the main asteroid belt and some of them are linked to the main belt comets. Brand-new albedo data brought by AKARI opens the possibility of detection of water ice on the C-type asteroids. Here we propose to make the spectroscopic observations with the Subaru telescope in the near-infrared wavelengths to detect water ice on these high-albedo C-type asteroids. Thanks to a large aperture of Subaru telescope and a high altitude of Mauna Kea, it can be only possible to observe a weak signal of the existence of water on the surface of asteroids with a certain S/N. In addition, using the imaging data taken prior to IRCS spectroscopic mode, we intend to seek any comet-like activities by investigating diffuseness of the asteroids, which can be detected by comparing the observed point-spread functions with those of field stars.

A Survey of Rotation Lightcurves of Small Jovian Trojan Asteroids in the L4 Cloud

NASA Astrophysics Data System (ADS)

French, Linda M.; Stephens, Robert; Warner, Brian; James, David; Rohl, Derrick; Connour, Kyle

2017-10-01

Jovian Trojan asteroids are of interest both as objects in their own right and as possible relics of Solar System formation. Several lines of evidence support a common origin for, and possible hereditary link between, Jovian Trojan asteroids and cometary nuclei. Asteroid lightcurves give information about processes that have affected a group of asteroids including their density. Due to their distance and low albedos, few comet-sized Trojans have been studied. We have been carrying out a survey of Trojan lightcurve properties comparing small Trojan asteroids with comets (French et al 2015). We present new lightcurve information for 39 Trojans less than about 35 km in diameter. We report our latest results and compare them with results from the sparsely-sampled lightcurves from the Palomar Transient Factory (Waszazak et al., Chang et al. 2015). The minimum densities for objects with complete lightcurves are estimated and are found to becomparable to those measured for cometary nuclei. A significant fraction (~40%) of thisobserved small Trojan population rotates slowly (P > 24 hours), with measured periods as over 500 hours (Waszczak et al 2015). 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.

The 1908 Tunguska explosion - Atmospheric disruption of a stony asteroid

NASA Technical Reports Server (NTRS)

Chyba, Christofer F.; Thomas, Paul J.; Zahnle, Kevin J.

1993-01-01

The explosion over Tunguska, Central Siberia, in 1908 released 10 to 20 megatons (high explosive equivalent) of energy at an altitude of about 10 km. This event represents a typical fate for stony asteroids tens of meters in radius entering the Earth's atmosphere at common hypersonic velocities. Comets and carbonaceous asteroids of the appropriate energy disrupt too high, whereas typical iron objects reach and crater the terrestrial surface.

Asteroid Origins Satellite (AOSAT) I: An On-orbit Centrifuge Science Laboratory

NASA Astrophysics Data System (ADS)

Lightholder, Jack; Thoesen, Andrew; Adamson, Eric; Jakubowski, Jeremy; Nallapu, Ravi; Smallwood, Sarah; Raura, Laksh; Klesh, Andrew; Asphaug, Erik; Thangavelautham, Jekan

2017-04-01

Exploration of asteroids, comets and small moons (small bodies) can answer fundamental questions relating to the formation of the solar system, the availability of resources, and the nature of impact hazards. Near-earth asteroids and the small moons of Mars are potential targets of human exploration. But as illustrated by recent missions, small body surface exploration remains challenging, expensive, and fraught with risk. Despite their small size, they are among the most extreme planetary environments, with low and irregular gravity, loosely bound regolith, extreme temperature variation, and the presence of electrically charged dust. Here we describe the Asteroid Origins Satellite (AOSAT-I), an on-orbit, 3U CubeSat centrifuge using a sandwich-sized bed of crushed meteorite fragments to replicate asteroid surface conditions. Demonstration of this CubeSat will provide a low-cost pathway to physical asteroid model validation, shed light on the origin and geophysics of asteroids, and constrain the design of future landers, rovers, resource extractors, and human missions. AOSAT-I will conduct scientific experiments within its payload chamber while operating in two distinct modes: (1) as a nonrotating microgravity laboratory to investigate primary accretion, and (2) as a rotating centrifuge producing artificial milligravity to simulate surface conditions on asteroids, comets and small moons. AOSAT-I takes advantage of low-cost, off-the-shelf components, modular design, and the rapid assembly and instrumentation of the CubeSat standard, to answer fundamental questions in planetary science and reduce cost and risk of future exploration.

Animation Sequence of Comet Wild2 Once More Demonstrates Shape Peculiarities of Small Celestial Bodies

NASA Astrophysics Data System (ADS)

Kochemasov, G. G.

The outstanding success of the Stardust mission having acquired in January 2004 images of Comet Wild2 allows us to compare them with images of some other small objects: satellites, asteroids, comets and confirm the earlier conclusion about prevailing shaping forces [1, 2]. The excellent images of the Comet Wild2 core (the best up to date among comets, Internet) show that it is not ``a ball of dirty ice and rock'' but rather a convexo-concave object resembling other small bodies. They all, independently of their nature, sizes, compositions, demonstrate oblong ``banana''-type style. This is a result of pressing in one side and bulging out another antipodean one (the fundamental wave action). Comet Wild2 (5.4 km long core) in this sense can be perfectly compared with asteroid Mathilde (60 km) and satellite Thebe (˜ 116 km). All three have deeply concave hemisphere opposed by clearly convex one. Bulging out friable material often induces deep fracturing of convex hemispheres. This is well visible in comet Borrelli (8 km long core) and especially pronounced in asteroids Eros (33 km) and Annefrank (`˜ 6 km). Deep ``saddle'' at the convex side of both makes their images rather similar. Another characteristic of small oblong bodies is a principal shape difference of two elongated ends: one is blunt, another sharp. Principally, it is the same process which makes the ``banana''-shape (wave1) but of a smaller scale (wave2). The blunt end is made by pressing in, the sharp end by bulging out. Obviously, an impact sculpturing cannot give similar complex forms in so different bodies. The main principal shaping is done by standing inertia-gravity waves arising in celestial bodies in response to their movement in elliptical orbits with periodically changing accelerations. The fundamental wave1 makes convexo-concave shape, the first overtone wave2 sharp-blunt ends. Larger celestial bodies: satellites, planets, stars react to these waves by universal tectonic dichotomy and sectoring [3]. The arctic-antarctic symptom (after Earth) is typical manifestation of sectoring with two antepodean sectors: one pressed in, another bulged out. References: [1] Kochemasov G.G. (1999) On convexo-concave shape of small celestial bodies // ``Asteroids, Comets, Meteors'' conference, Cornell Univ., U.S.A., July 1999, Abstract # 24. 22; [2] Kochemasov G.G. (2002) ``Dirty snowball'' -- now is too primitive for a scientific description of comets // 34th COSPAR Scientific Assembly at the World Space Congress 2002, 10-19 Oct. 2002, Houston, Texas, USA, (CD-ROM); [3] Kochemasov G.G. (1999) Theorems of wave planetary tectonics // Geophys. Res. Abstr., Vol. 1, # 3, 700.

Main Belt Comet P/2006 VW139: A Fragment from a Recent Collision?

NASA Astrophysics Data System (ADS)

Novakovic, B.; Hsieh, H. H.; Cellino, A.

2012-05-01

We applied different methods to examine a possibility that main belt comet P/2006VW139, recently discovered by the Pan-STARRS 1, belongs to a small group of 24 asteroids. Results show strong evidence that P/2006VW139 really belongs to this group.

Getting together in deep space - The Rosetta space probe's long trek to Comet 67/P Churyumov-Gerasimenko

NASA Astrophysics Data System (ADS)

2004-02-01

The countdown to Rosetta’s rendezvous in space began on 1 March 1997. At the end of February 2004, seven years and not a few headaches later, the European Space Agency (ESA) probe will at last be setting off on its journey to meet Comet Churyumov-Gerasimenko. The long-planned get-together will not however take place until the middle of 2014. A few months after arriving at the comet, Rosetta will release a small lander onto its surface. Then, for almost two years it will investigate Churyumov-Gerasimenko from close up. Dr Gerhard Schwehm, lead scientist for the Rosetta project, explains that, “With this mission we will be breaking new ground - this will be the first protracted cometary encounter.” The trip to the meeting place in space will certainly be a long one, located as it is some 4.5 astronomical units from the Sun, which translates into something like 675 million kilometres. Rosetta will be on the road for ten years, during which time it will clock up in excess of five billion kilometres. Launch in February 2004 Rosetta will be waved off on 26 February when it lifts off from the space centre in Kourou, French Guiana, aboard an Ariane 5 launcher. Shortly after the spacecraft’s release, its solar panels will be deployed and turned towards the Sun to build up the necessary power reserves. Its various systems and experiments will be gradually brought into operation and tested. Just three months into the mission the first active phase will be over, followed by final testing of the experiments in October 2004. Rosetta will then spend the following years flying a lonely path to the comet, passing by the Earth, Mars, the Earth and the Earth again. There is no alternative to this detour, for even Ariane 5, the most powerful launcher on the market today, lacks the power to hurl the probe on a direct route to the comet. To get the required momentum, it will rely on swing-by manœuvres, using the gravitation pull of Mars (in 2007) and the Earth (three times, in 2005, 2007 and 2008) to pick up speed. Asteroids for company A change is as good as a rest, and a meeting with at least one asteroid should help break the monotony for Rosetta. The spacecraft will come close to an asteroid at the end of 2008. Asteroids are, it will be remembered, rocky bodies, some as large as mountains, some even larger, that orbit the Sun in much the same way as planets. “These ‘brief encounters’ are a scientific opportunity and also a chance to test Rosetta’s instrument payload,” says Gerhard Schwehm. But asteroid exploration also serves an entirely practical purpose: “The more we find out about them, the better the prospect of being able one day to avert a possible collision.” Following a period of low-activity cruising, the probe’s course will be adjusted one last time in May 2011. From July 2011, a further two-and-a-half years' radio silence will be observed, and Rosetta, left entirely to its own resources, will fly close to the Jupiter orbit. Link-up in 2014 Finally, in January 2014, the probe will be reactivated and will, by October 2014, be only a few kilometres distant from Churyumov-Gerasimenko. This is where the dream of so many scientists becomes reality. Having deposited its precious lander cargo on the comet’s surface, Rosetta will continue to orbit Churyumov-Gerasimenko and together they will spend the next seventeen months flying towards the Sun. Rosetta was built by an international consortium led by Astrium. The lander probe was developed in Cologne under the aegis of the DLR, Germany’s space agency, with contributions from ESA and research centres in Austria, Finland, France, Hungary, Ireland, Italy and Great Britain. The comet explorer carries ten scientific instruments. Their job is to draw out the secrets of the comet’s chemical and physical composition and reveal its magnetic and electrical properties. Using a specially designed camera, the lander will take pictures in the macro and micro ranges and send all the data thus acquired back to Earth, via Rosetta. “This will be our first ever chance to be there, at first hand, so to speak, as a comet comes to life,” Schwehm goes on to explain. When Churyumov-Gerasimenko gets to within about 500 million kilometres of the Sun, the frozen gases that envelop it will evaporate and a trail of dust will be blown back over hundreds of thousands of kilometres. When illuminated by the Sun, this characteristic comet tail then becomes visible from Earth. In the course of the mission, the processes at work within the cometary nucleus will be studied and measured more precisely than has ever before been possible, for earlier probes simply flew past their targets. “As we will be accompanying Churyumov-Gerasimenko for two years, until the comet reaches the point closest to the Sun and travels away from it, we can at long last hope to acquire new knowledge about comets. We are confident we will come a step nearer to understanding the origins and formation of our solar system and the emergence of life on Earth.” More information on the Rosetta launch can be found on : http://www.esa.int/rosetta. More on ESA Science Programme at : http://www.esa.int/science

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. Thus such asteroids are known as the Trojans and the mentioned programme is referred to as the Uppsala-DLR Trojan Survey . In September and October/November 1996, the ESO Schmidt telescope was used to cover about 900 square degrees twice centered on the sky field in the direction of the Jovian L4 point. The observations were made by ESO night-assistants Guido and Oscar Pizarro . By inspection of those from September, Claes-Ingvar Lagerkvist found a total of about 400 Trojan asteroids, most of which were hitherto unknown. Their accurate positions were measured on a two-coordinate measuring machine at the ESO Headquarters in Garching (Germany). During the same period, the 0.6-m Bochum telescope at La Silla was used for additional observations of positions and magnitudes. An asteroid with a tail? ESO Press Photo 31a/97 ESO Press Photo 31a/97 [JPG, 120k] Caption: Discovery image of P/1997 T3 , obtained on October 1, 1997, with the 1-metre ESO Schmidt telescope at the La Silla observatory in the Chilean Atacama desert. The object is seen as a small straight and sharp `asteroidal' trail (in 4 o'clock orientation) on the lower right side of the strong white line in the middle of the field, directly opposite the white dot (these marks were placed in order to mark the position of the new object on the film). A new object was found by Claes-Ingvar Lagerkvist on a film obtained with the ESO 1-metre Schmidt telescope on October 1, 1997. The appearance was that of a point light source, i.e. it was presumably of asteroidal nature , cf. ESO Press Photo 31a/97. ESO Press Photo 31b/97 ESO Press Photo 31b/97 [JPG, 45k] Caption: P/1997 T3 on October 6, 1997 at 05:13:54 UT. This image of the new object (slightly above and to the left of the centre of the field) was obtained with the 0.6-m Bochum telescope at La Silla; the observer was Andreas Nathues . The tail is faintly visible to the lower left of the point-like object (in the 7 o'clock direction). However, when Andreas Nathues (DLR, Institute of Planetary Exploration) soon thereafter obtained seven unfiltered CCD images on three consecutive nights with the 60-cm `Bochum telescope' at La Silla, Uri Carsenty found a tail extending 15 arcseconds in the WSE direction from the point source, cf. ESO Press Photo 31b/97. The (red) magnitude was about 19, or 150,000 times fainter than what is visible to the naked eye. More observations were obtained at La Silla during the following nights, confirming the persistent presence of this tail. NTT observations confirm the cometary nature of P/1997 T3 ESO Press Photo 31c/97 ESO Press Photo 31c/97 [JPG, 52k] Caption: Deep NTT image of P/1997 T3. This image covers a field of 105 x 60 arcsec and is a composite of several CCD exposures. It was taken with the ESO New Technology Telescope (NTT) and the EMMI multi-mode instrument by ESO astronomers Hermann Boehnhardt and Olivier Hainaut on different days between 21 and 25 October 1997. By computer processing, the images of P/1997 T3 are aligned to the same pixel position and co-added in order to increase the visibility of the comet. Due to the motion of the comet, multiple images of several galaxies and stars appear in this photo. At the time of the observations, the comet was about 3.34 AU from Earth and about 4.30 AU from the Sun. A larger version [JPG, 384k] is also available. In late October 1997, further images of the new object and its tail were taken with the ESO 3.5-m New Technology Telescope (NTT) at La Silla, cf. ESO Press Photo 31c/97. On these, the narrow tail was seen to be at least 90 arcsec long and pointing roughly in the Sun direction . The steady appearance and the sunward orientation of the tail indicates that it consists of dust. Moreover, a preliminary image analysis shows the presence of a weak and very condensed coma of dust grains around the nucleus. Interestingly, a series of images through several broadband filters with a total of almost 30 min exposure time did not show any trace of a normal, anti-sunward tail seen in most comets. Still, these observations indicate that the object resembles a typical comet much more than originally thought. This is also supported by the fact that its orbit, calculated on the basis of positional observations during the past month, has been found to be moderately elongated (eccentricity 0.36). The mean distance to the Sun is 6.67 AU (1000 million kilometres), but it comes as close as 4.25 AU (635 million kilometres) at its perihelion. The orbital period is about 17 years. More observations needed! It will be interesting to follow this new object in coming years. Will it remain `cometary' or will the unusual tail disappear after a while? Could it be that some `asteroids' in `cometary' orbits, if observed in more detail with a larger telescope, as was done in this case with the NTT, will also turn out to have a faint coma and even a tail? It is at this moment still unknown which implications the discovery of apparently `intermediate' objects may have on our understanding of the origin and evolution of the solar system. In particular, it is not at all clear whether they represent a completely new class of objects with an internal structure (and composition?) that is significantly different from a `dirty-snowball' cometary nucleus or a rocky asteroid. It may also be that some asteroids have substantial deposits of icy material on or near the surface that may be set free under certain circumstances and mimic cometary activity. This might in theory happen by collisions with other, smaller objects or due to an internal heat source. Only further observations of such objects will allow to tell. Where to find more information Here are some WWW-addresses where more useful information may be obtained about the comet/asteroid phenomenon: * http://www.dlr.de/Berlin/ - Small Bodies Group at the DLR (Berlin, Germany) * http://www.astro.uu.se/planet/asteroid - Asteroids' page of the Uppsala planetary system group (Sweden) * http://www.skypub.com/comets/1996n2pw.html - Are They Comets or Asteroids? (adapted version of article by Stuart J. Goldman in Sky & Telescope, November 1996) * http://cfa-www.harvard.edu/~graff/pressreleases/1996PW.html - Two Unusual Objects: 1996 PW and C/1996 N2 (Press information from the Harvard-Smithsonian Center for Astrophysics (CfA), Cambridge, Massachusetts, U.S.A.) * Abstract of research article : Origin and Evolution of the Unusual Object 1996 PW: Asteroids from the Oort Cloud? by Paul R. Weissman and Harold F. Levison * Abstract of research article : The Main Asteroid Belt - Comet Graveyard or Nursery? by Mark Hammergren * Preprint of research article : The Lightcurve and Colours of Unusual Minor Planet 1996 PW by J.K. Davies et al. This Press Release is accompanied by ESO PR Photo 31a/97 [JPG, 120k] , ESO PR Photo 31b/97 [JPG, 45k] and ESO PR Photo 31c/97 [JPG, 52k]. A larger version of ESO PR Photo 31c/97 [JPG, 384k] is also available. They may be reproduced, if credit is given to the European Southern Observatory. How to obtain ESO Press Information ESO Press Information is made available on the World-Wide Web (URL: http://www.eso.org ).

Comet Christensen Has Carbon Gas

NASA Image and Video Library

2015-11-23

An expanded view of comet C/2006 W3 (Christensen) is shown here. The WISE spacecraft observed this comet on April 20th, 2010 as it traveled through the constellation Sagittarius. Comet Christensen was nearly 370 million miles (600 million kilometers) from Earth at the time. The extent of the dust, about a tenth of a degree across in this image, is about 2/3rds the diameter of the sun. The red contours show the signal from the gas emission observed by the WISE spacecraft in the 4.6 micron wavelength channel, which contains carbon monoxide (CO) and carbon dioxide (CO2) emission lines. The strength of the 4.6 micron signal indicates over half a metric ton per second of CO or CO2 was emitted from this comet at the time of the observations. The WISE spacecraft was put into hibernation in 2011 upon completing its goal of surveying the entire sky in infrared light. WISE cataloged three quarters of a billion objects, including asteroids, stars and galaxies. In August 2013, NASA decided to reinstate the spacecraft on a mission to find and characterize more asteroids. http://photojournal.jpl.nasa.gov/catalog/PIA20119

Guidance and navigation requirements for unmanned flyby and swingby missions to the outer planets. Volume 4: High thrust mission, part 2, phase C

NASA Technical Reports Server (NTRS)

1971-01-01

The guidance and navigation requirements for a set of impulsive thrust missions involving one or more outer planets or comets. Specific missions considered include two Jupiter entry missions of 800 and 1200 day duration, two multiple swingby missions with the sequences Jupiter-Uranus-Neptune and Jupiter-Saturn-Pluto, and two comets rendezvous missions involving the short period comets P/Tempel 2 and P/Tuttle-Giacobini-Kresak. Results show the relative utility of onboard and Earth-based DSN navigation. The effects of parametric variations in navigation accuracy, measurement rate, and miscellaneous constraints are determined. The utility of a TV type onboard navigation sensor - sighting on planetary satellites and comets - is examined. Velocity corrections required for the nominal and parametrically varied cases are tabulated.

Hummingbird Comet Nucleus Analysis Mission

NASA Technical Reports Server (NTRS)

Kojiro, Daniel; Carle, Glenn C.; Lasher, Larry E.

2000-01-01

Hummingbird is a highly focused scientific mission, proposed to NASA s Discovery Program, designed to address the highest priority questions in cometary science-that of the chemical composition of the cometary nucleus. After rendezvous with the comet, Hummingbird would first methodically image and map the comet, then collect and analyze dust, ice and gases from the cometary atmosphere to enrich characterization of the comet and support landing site selection. Then, like its namesake, Hummingbird would carefully descend to a pre-selected surface site obtaining a high-resolution image, gather a surface material sample, acquire surface temperature and then immediately return to orbit for detailed chemical and elemental analyses followed by a high resolution post-sampling image of the site. Hummingbird s analytical laboratory contains instrumentation for a comprehensive molecular and elemental analysis of the cometary nucleus as well as an innovative surface sample acquisition device.

A collision in 2009 as the origin of the debris trail of asteroid P/2010 A2.

PubMed

Snodgrass, Colin; Tubiana, Cecilia; Vincent, Jean-Baptiste; Sierks, Holger; Hviid, Stubbe; Moissl, Richard; Boehnhardt, Hermann; Barbieri, Cesare; Koschny, Detlef; Lamy, Philippe; Rickman, Hans; Rodrigo, Rafael; Carry, Benoît; Lowry, Stephen C; Laird, Ryan J M; Weissman, Paul R; Fitzsimmons, Alan; Marchi, Simone

2010-10-14

The peculiar object P/2010 A2 was discovered in January 2010 and given a cometary designation because of the presence of a trail of material, although there was no central condensation or coma. The appearance of this object, in an asteroidal orbit (small eccentricity and inclination) in the inner main asteroid belt attracted attention as a potential new member of the recently recognized class of main-belt comets. If confirmed, this new object would expand the range in heliocentric distance over which main-belt comets are found. Here we report observations of P/2010 A2 by the Rosetta spacecraft. We conclude that the trail arose from a single event, rather than a period of cometary activity, in agreement with independent results. The trail is made up of relatively large particles of millimetre to centimetre size that remain close to the parent asteroid. The shape of the trail can be explained by an initial impact ejecting large clumps of debris that disintegrated and dispersed almost immediately. We determine that this was an asteroid collision that occurred around 10 February 2009.

Enhanced Gravity Tractor Derived from the Asteroid Redirect Mission for Deflecting Hypothetical Asteroid 2017 PDC

NASA Technical Reports Server (NTRS)

Mazanek, Daniel D.; Reeves, David M.; Abell, Paul A.; Shen, Haijun; Qu, Min

2017-01-01

The Asteroid Redirect Mission (ARM) concept would robotically visit a hazardous-size near-Earth asteroid (NEA) with a rendezvous spacecraft, collect a multi-ton boulder and regolith samples from its surface, demonstrate an innovative planetary defense technique known as the Enhanced Gravity Tractor (EGT), and return the asteroidal material to a stable orbit around the Moon, allowing astronauts to explore the returned material in the mid-2020s. Launch of the robotic vehicle to rendezvous with the ARM reference target, NEA (341843) 2008 EV5, would occur in late 2021 [1,2]. The robotic segment of the ARM concept uses a 40 kW Solar Electric Propulsion (SEP) system with a specific impulse (Isp) of 2600 s, and would provide the first ever demonstration of the EGT technique on a hazardous-size asteroid and validate one method of collecting mass in-situ. The power, propellant, and thrust capability of the ARM robotic spacecraft can be scaled from a 40 kW system to 150 kW and 300 kW, which represent a likely future power level progression. The gravity tractor technique uses the gravitational attraction of a station-keeping spacecraft with the asteroid to provide a velocity change and gradually alter the trajectory of the asteroid. EGT utilizes a spacecraft with a high-efficiency propulsion system, such as Solar Electric Propulsion (SEP), along with mass collected in-situ to augment the mass of the spacecraft, thereby increasing the gravitational force between the objects [3]. As long as the spacecraft has sufficient thrust and propellant capability, the EGT force is only limited by the amount of in-situ mass collected and can be increased several orders of magnitude compared to the traditional gravity tractor technique in which only the spacecraft mass is used to generate the gravitational attraction force. This increase in available force greatly reduces the required deflection time. The collected material can be a single boulder, multiple boulders, regolith, or a combination of different material types using a variety of collection techniques. The EGT concept assumes that the ability to efficiently collect asteroid mass in-situ from a wide variety of asteroid types and environments is a future capability that will be developed and perfected in the future by the asteroid mining community. Additionally, it is anticipated that the mass collection would likely be performed by a single or multiple separable spacecraft to allow the SEP spacecraft to operate at safe distance from the asteroid.

The Big Splash: Tsunami from Large Asteroid and Comet Impacts

NASA Astrophysics Data System (ADS)

Hills, J.; Goda, M.

Asteroid and comet impacts produce a large range of damage. Tsunami may produce most of the economic damage in large asteroid impacts. Large asteroid impacts produce worldwide darkness lasting several months that may kill more people by mass starvation, especially in developing countries, than would tsunami, but the dust should not severely affect economic infrastructure. The tsunami may even kill more people in developed countries with large coastal populations, such as the United States, than the starvation resulting from darkness. We have been determining which regions of Earth are most susceptible to asteroid tsunami by simulating the effect of a large asteroid impact into mid-ocean. We have modeled the effect of midAtlantic and midPacific impacts that produce craters 300 to 150 km in diameter. A KT-size impactor would cause the larger of these craters. We used a computer code that has successfully determined the runup and inundation from historical earthquake-generated tsunami. The code has been progressively improved to eliminate previous problems at the domain boundaries, so it now runs until the tsunami inundation is complete. We find that the larger of these two midAtlantic impacts would engulf the entire Florida Peninsula. The smaller one would inundate the eastern third of the peninsula while a tsunami passing through the Gulf of Cuba would inundate the West Coast of Florida. Impacts at three different sites in the Pacific show the great vulnerability of Tokyo and its surroundings to asteroid tsunami. Mainland Asia is relatively protected from asteroid tsunami. In Europe, the Iberian Peninsula and the Atlantic Providences of France are highly vulnerable to asteroid tsunami.

Consequences of impacts of small asteroids and comets with Earth

NASA Technical Reports Server (NTRS)

Hills, J. G.

1994-01-01

The fragmentation of a small asteroid in the atmosphere greatly increases its cross sections for aerodynamic braking and energy dissipation. At a typical impact velocity of 22 km/s, the atmosphere absorbs more than half the kinetic energy of stony meteoroids with diameters, D(sub m), less than 220 m and iron meteoroids with D(sub m) less than 80 m. The corresponding diameter for comets with impact velocity 50 km/s is D(sub m) less than 1600 m. Most of the atmospheric energy dissipation occurs in a fraction of a scale height, so large meteors appear to 'explode' or 'flare' at the end of their visible paths. This dissipation of energy in the atmosphere protects the earth from direct impact damage (e.g., craters), but it produces a blast wave that can do considerable damage. The area of destruction around the impact point in which the over-pressure in the blast wave exceeds 4 lb/sq in = 2.8 x 10(exp 5) dynes/cu cm, which is enough to knock over trees and destroy buildings, increases rapidly from zero for chondritic meteoroids less than 56 m in diameter (15 megatons) to about 200 sq km for those 80 m in diameter (48 megatons); the probable diameter of the tunguska impactor of 1908 is about 80 m. Crater formation and earthquakes are not significant in land impacts by stony asteroids less than about 200 m in diameter because of the air protection. A tsunami is probably the most devastating type of damage for asteroids 200 m to 1 km in diameter. An impact by an asteroid this size anywhere in the Atlantic would devastate coastal areas on both sides of the ocean. An asteroid a few kilometers across would produce a tsunami that would reach the foothills of the Appalachian Mountains in the upper half of the East Coast of the United States. Most of Florida is protected from a tsunami by the gradual slope of the ocean off its coast, which causes most of the tsunami energy to be reflected back into the Atlantic. The atmosphere plume produced by asteroids with diameters exceeding about 120 m cannot be contained by the atmosphere, so this bubble of high-temperature gas forms a new layer on top of the atmosphere. The dust entrapped in this hot gas is likely to have optical depths exceeding tau = 10 for asteroids with diameters exceeding about 0.5 to 1 km. The optical flux from asteroids 60 m or more in diameter is enough to ignite pine forests. However, the blast wave from an impacting asteroid goes beyond the radius in which the fire starts. The blast wave tends to blow out the fire, so it is likely that the impact will char the forest, as at Tunguska, but the impact will not produce a sustained fire. Because comets dissipate their energy much higher in the atmosphere than asteroids, they illuminate a much larger region and their blast wave is weaker. So they are much more effective in producing large fires. This suggests that the KT impactor was a comet rather than an asteroid.

Samples of Asteroid Surface Ponded Deposits in Chondritic Meteorites

NASA Technical Reports Server (NTRS)

Zolensky, M. E.; Lee, R.; Le, L.

2004-01-01

One of the many unexpected observations of asteroid 433 Eros by the Near Earth Asteroid Rendezvous (NEAR) mission was the many ponds of fine-grained materials [1-3]. The ponds have smooth surfaces, and define equipotential surfaces up to 10's of meters in diameter [4]. The ponds have a uniformly sub-cm grain size and appear to be cohesive or indurated to some degree, as revealed by slumping. The ponds appear to be concentrated within 30 degrees of the equator of Eros, where gravity is lowest. There is some insight into the mineralogy and composition of the ponds surfaces from NEAR spectroscopy [2,4,5,6]. Compared to the bulk asteroid, ponds: (1) are distinctly bluer (high 550/760 nm ratio), (2) have a deeper 1um mafic band, (3) have reflectance elevated by 5%.

Mission Analysis for the Don Quijote Phase-A Study

NASA Technical Reports Server (NTRS)

Cano, Juan L.; Sanchez, Mariano; Cornara, Stefania; Carnelli, Ian

2007-01-01

The Don Quijote Phase-A study is a definition study funded by ESA and devoted to the analysis of the possibilities to deflect a Near Earth Object (NEO) in the range of 300-800 m diameter. DEIMOS Space S.L. and EADS Astrium have teamed up within this study to form one of the three consortia that have analyzed these aspects for ESA. Target asteroids for the mission are 1989 ML, 2002 AT4 and Apophis. This paper presents the mission analysis activities within the consortium providing: low-thrust interplanetary rendezvous Orbiter trajectories to the target asteroids, ballistic interplanetary trajectories for the Impactor, Orbiter arrival description at the asteroids, Orbiter stable orbits characterization at the asteroid, deflection determination by means of a Radio Science Experiment (RSE) as well as the mission timelines and overall mission scenarios.

A Wide-Angle Camera for the Mobile Asteroid Surface Scout (MASCOT) on Hayabusa-2

NASA Astrophysics Data System (ADS)

Schmitz, N.; Koncz, A.; Jaumann, R.; Hoffmann, H.; Jobs, D.; Kachlicki, J.; Michaelis, H.; Mottola, S.; Pforte, B.; Schroeder, S.; Terzer, R.; Trauthan, F.; Tschentscher, M.; Weisse, S.; Ho, T.-M.; Biele, J.; Ulamec, S.; Broll, B.; Kruselburger, A.; Perez-Prieto, L.

2014-04-01

JAXA's Hayabusa-2 mission, an asteroid sample return mission, is scheduled for launch in December 2014, for a rendezvous with the C-type asteroid 1999 JU3 in 2018. MASCOT, the Mobile Asteroid Surface Scout [1], is a small lander, designed to deliver ground truth for the orbiter remote measurements, support the selection of sampling sites, and provide context for the returned samples.MASCOT's main objective is to investigate the landing site's geomorphology, the internal structure, texture and composition of the regolith (dust, soil and rocks), and the thermal, mechanical, and magnetic properties of the surface. MASCOT comprises a payload of four scientific instruments: camera, radiometer, magnetometer and hyper-spectral microscope. The camera (MASCOT CAM) was designed and built by DLR's Institute of Planetary Research, together with Airbus DS Germany.

Incorporating Uncertainty into Spacecraft Mission and Trajectory Design

NASA Astrophysics Data System (ADS)

Juliana D., Feldhacker

The complex nature of many astrodynamic systems often leads to high computational costs or degraded accuracy in the analysis and design of spacecraft missions, and the incorporation of uncertainty into the trajectory optimization process often becomes intractable. This research applies mathematical modeling techniques to reduce computational cost and improve tractability for design, optimization, uncertainty quantication (UQ) and sensitivity analysis (SA) in astrodynamic systems and develops a method for trajectory optimization under uncertainty (OUU). This thesis demonstrates the use of surrogate regression models and polynomial chaos expansions for the purpose of design and UQ in the complex three-body system. Results are presented for the application of the models to the design of mid-eld rendezvous maneuvers for spacecraft in three-body orbits. The models are shown to provide high accuracy with no a priori knowledge on the sample size required for convergence. Additionally, a method is developed for the direct incorporation of system uncertainties into the design process for the purpose of OUU and robust design; these methods are also applied to the rendezvous problem. It is shown that the models can be used for constrained optimization with orders of magnitude fewer samples than is required for a Monte Carlo approach to the same problem. Finally, this research considers an application for which regression models are not well-suited, namely UQ for the kinetic de ection of potentially hazardous asteroids under the assumptions of real asteroid shape models and uncertainties in the impact trajectory and the surface material properties of the asteroid, which produce a non-smooth system response. An alternate set of models is presented that enables analytic computation of the uncertainties in the imparted momentum from impact. Use of these models for a survey of asteroids allows conclusions to be drawn on the eects of an asteroid's shape on the ability to successfully divert the asteroid via kinetic impactor.

Global environmental effects of impact-generated aerosols: Results from a general circulation model

NASA Technical Reports Server (NTRS)

Covey, Curt; Ghan, Steven J.; Walton, John J.; Weissman, Paul R.

1989-01-01

Interception of sunlight by the high altitude worldwide dust cloud generated by impact of a large asteroid or comet would lead to substantial land surface cooling, according to the three-dimensional atmospheric general circulation model (GCM). This result is qualitatively similar to conclusions drawn from an earlier study that employed a one-dimensional atmospheric model, but in the GCM simulation the heat capacity of the oceans, not included in the one-dimensional model, substantially mitigates land surface cooling. On the other hand, the low heat capacity of the GCM's land surface allows temperatures to drop more rapidly in the initial stages of cooling than in the one-dimensional model study. GCM-simulated climatic changes in the scenario of asteroid/comet winter are more severe than in nuclear winter because the assumed aerosol amount is large enough to intercept all sunlight falling on earth. Impacts of smaller objects could also lead to dramatic, though of course less severe, climatic changes, according to the GCM. An asteroid or comet impact would not lead to anything approaching complete global freezing, but quite reasonable to assume that impacts would dramatically alter the climate in at least a patchy sense.

Could 433 Eros have a Primitive Achondritic Composition?

NASA Technical Reports Server (NTRS)

Burbine, T. H.; McCoy, T. J.; Nittler, L. R.; Bell, J. F., III

2001-01-01

One of the goals of the NEAR (Near Earth Asteroid Rendezvous) mission to 433 Eros is to determine if it has a meteoritic analog. We are currently investigating if primitive achondrites have bulk compositions and spectral properties similar to Eros. Additional information is contained in the original extended abstract.

Investigation of the interior of primordial asteroids and the origin of the Earth's water: The INSIDER space mission

NASA Astrophysics Data System (ADS)

Vernazza, P.; Lamy, P.

2014-07-01

Today's asteroid belt may not only be populated by objects that formed in situ, typically between 2.2 and 3.3 au, but also by bodies that formed over a very large range of heliocentric distances. It is currently proposed that both the early (<5 Myrs after Solar System formation) and late (>700 Myrs after Solar System formation) dynamical evolution of the Solar System was governed by giant planet migrations that led to the insertion of inner (1--3 au) as well as outer (4--13 au) small bodies in the asteroid belt. Taken altogether, the current dynamical models are able to explain many striking features of the asteroid belt including i) its incredible compositional diversity deduced mainly from spectroscopic observations and meteorites measurements, and ii) the evidence of radial mixing experienced by the various asteroid classes (e.g., S-, C-types) after their formation. In a broad stroke, the idea that the asteroid belt is a condensed version of the primordial Solar System is progressively emerging. The asteroid belt therefore presents the double advantage of being easily accessible and of offering crucial tests for the formation models of the Solar System by exploring the building blocks predicted by models of i) the telluric planets, ii) the giant planet cores, iii) the giant planets' satellites, and iv) outer small bodies such TNOs and comets. It also appears as an ideal place to search for the origin of Earth's water. Up to now, only a few asteroid classes (e.g., several S-types) have been visited by spacecraft and the focus of these in situ measurements has been mainly to give a geological context to ground based observations as well as strengthen/validate their interpretation. Most of the tantalizing discoveries of asteroid missions have been realized via images of the objects surfaces. Time has come for asteroid space science to reach a new milestone by extending the reconnaissance of the Belt's diversity and addressing new science questions. The scientific objectives of the INSIDER mission, to be proposed in response to the 2014 ESA call for an M-class mission, require the exploration of diverse primordial asteroids --- possibly the smallest surviving protoplanets of our Solar System --- in order to constrain the earliest stages of planetesimal formation thus avoiding the effect of destructive collisions, which produce extensively processed rubble piles. Our science objectives that justify in situ measurements in the context of an M-class mission and that are expected to lead to significant breakthroughs include: - The exploration of the diversity of the asteroid belt - The first investigation of the internal structure of asteroids - The origin of water on Earth The proposed mission scenario consists in i) successive rendez-vous followed by orbit insertion of two and possibly three large (D>100 km) objects, ii) one or two small landing modules (MASCOT type) to perform cosmochemical measurements (D/H ratio, O isotopes). The potential targets would include 24 Themis and 10 Hygiea. Meeting our science objectives requires instruments (such as radar, seismometers to be dropped to the surface, magnetometer, high resolution laser-desorption-ionization mass spectrometer to analyse the surface samples) not flown so far during past asteroids missions along with the traditional powerhouses, such as cameras and spectrometers.

Organic Chemistry in Space

NASA Technical Reports Server (NTRS)

Charnley, Steven

2009-01-01

Astronomical observations, theoretical modeling, laboratory simulation and analysis of extraterrestrial material have enhanced our knowledge of the inventory of organic matter in the interstellar medium (ISM) and on small bodies such as comets and asteroids (Ehrenfreund & Charnley 2000). Comets, asteroids and their fragments, meteorites and interplanetary dust particles (IDPs), contributed significant amounts of extraterrestrial organic matter to the young Earth. This material degraded and reacted in a terrestrial prebiotic chemistry to form organic structures that may have served as building blocks for life on the early Earth. In this talk I will summarize our current understanding of the organic composition and chemistry of interstellar clouds. Molecules of astrobiological relevance include the building blocks of our genetic material: nucleic acids, composed of subunits such as N-heterocycles (purines and pyrimidines), sugars and amino acids. Signatures indicative of inheritance of pristine and modified interstellar material in comets and meteorites will also be discussed.

Earth-return trajectory options for the 1985-86 Halley opportunity

NASA Technical Reports Server (NTRS)

Farquhar, R. W.; Dunham, D. W.

1982-01-01

A unique and useful family of ballistic trajectories to Halley's comet is described. The distinguishing feature of this family is that all of the trajectories return to the Earth's vicinity after the Halley intercept. It is shown that, in some cases, the original Earth-return path can be reshaped by Earth-swingby maneuvers to achieve additional small-body encounters. One mission profile includes flybys of the asteroid Geographos and comet Tempel-2 following the Halley intercept. Dual-flyby missions involving comets Encke and Borrelly and the asteroid Anteros are also discussed. Dust and gas samples are collected during the high-velocity (about 70 km/sec) flythrough of Halley, and then returned to a high-apogee Earth orbit. Aerobraking maneuvers are used to bring the sample-return spacecraft to a low-altitude circular orbit where it can be recovered by the Space Shuttle.

Migration Processes and Volatiles Inventory to the Inner Planets

NASA Technical Reports Server (NTRS)

Marov, M. Y.; Ipatov, S. I.

2004-01-01

Comets and asteroids colliding with the terrestrial planets can deliver volatiles and organic or prebiotic compounds to the planets, thereby depositing on the planets the fundamental building-blocks for life. The inner planets contain heavier and cosmically less abundant elements in an iron-silicate matrix than the giant planets. This can be caused by the following three mechanisms: uneven fractionation and condensation in the accretionary disk; unequal degree of degassing of the composed matter; and heterogeneous accretion. Asteroid-size bodies consisting of the last low-temperature condensates (similar to most primitive chondritic meteorites, and enriched in hydrated silicates and trapped gases) are believed to have fallen onto the inner planets during the process of the giant planets formation. The relative contribution of either endogenous (i.e. outgassing) or exogenous (i.e. asteroid/comet collisions) sources is difficult to assess, although it is constrained by the pattern of noble gas abundances in the planetary atmospheres.

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 with several multiple asteroid systems located in the main belt. This mission concept uses the NASA's evolutionary Xenon Thruster (NEXT), the second generation of electric propulsion with 3 times more input power than the previous generation (NSTAR) of the Dawn mission. The mission objectives for each rendezvous asteroid are i) the characterization of the surface geology by direct imaging in visible and thermal infrared spectroscopy, ii) the characterization of the shape and gravity coupling visible observations with LIDAR ranging data, iii) the determination of the thermophysical properties of the surface, and iv) the identification of the surface composition by visible and near-infrared spectroscopy. The trajectory, science package and mission operations of the mission will be described. This work is supported by the National Science Foundation 05-608, "Astronomy and Astrophysics Research Grants (AAG)" No AST-0807468

Meteoroids and impact craters

USGS Publications Warehouse

Spall, H.

1986-01-01

Many meteoroids are associted with comets; as a comet travels around the sun it leaves a trail of debris behind it and it is this debris which produces meteor showers. Other meteoroids come from the asteroid belt, a zone between Mars and Jupiter filled with thousands of dwarf worlds that failed to coalesce into planets. 

Photometry of the comet 2060 Chiron

NASA Technical Reports Server (NTRS)

Buratti, Bonnie J.; Marcialis, Robert L.; Dunbar, R. Scott

1991-01-01

The comet 2060 Chiron has proven to be an interesting and enigmatic object. Situated between the orbits of Saturn and Uranus, it was originally classified as the most distant asteroid. It began to show cometary behavior in 1987 by increasing a full magnitude in brightness and developing a coma; there is evidence also for similar earlier outbursts. A thorough study of Chiron is important for two reasons: (1) it is a transition object defining the relationship between comets, asteroids, and meteorites; and (2) a full description of its changes in brightness - particularly on time scale of hours - will provide an empirical foundation for understanding the physical mechanisms (including outgassing, sublimation of volatiles, and even significant mass ejections) driving the evolution of comets. Short term outbursts were observed in early 1989, and a rapid decrease in brightness of Chiron's coma was observed in 1990 in the V and R filters. Also, a rotational lightcurve was detected of the nucleus with an amplitude only 1/4 that observed in its quiescent state: this fact indicates the increased importance of the optically thin coma to the observed brightness.

Dynamical evidence regarding the relationship between asteroids and meteorites

NASA Technical Reports Server (NTRS)

Wetherill, G. W.

1978-01-01

Meteorites are fragments of small solar system bodies transferring into the vicinity of earth from the inner edge of the asteroid belt. Photometric measurements support an association between Apollo objects and chondritic meteorites. Dynamical arguments indicate that most Apollo objects are devolatilized comet residues, however; petrographic and cosmogonical reasons argue against this conclusion.

Cometary Volatiles and the Origin of Comets

NASA Technical Reports Server (NTRS)

A'Hearn, Michael F.; Feaga, Lori M.; Keller, H. Uwe; Kawakita, Hideyo; Hampton, Donald L.; Kissel, Jochen; Klaasen, Kenneth P.; McFadden, Lucy A.; Meech, Karen J.; Schultz, Peter H.;

ESA Unveils Its New Comet Chaser.

NASA Astrophysics Data System (ADS)

1999-07-01

The objective is to study one of these primordial objects at close quarters by placing a lander on its surface and chasing, with an orbiter, the comet for millions of kilometres through space. Comets - among the oldest (4.6 billion years!) and last altered objects in the solar system - are regarded as the building blocks from which the planets formed. Thus the Rosetta's discoveries will allow the scientists to learn more about birth and evolution of the planets and about the origin of life on the Earth. The final design of the Rosetta orbiter will be revealed for the first time at the Royal Society in London on 1 July when a 1:4 scale model will be unveiled by ESA's Director of Science, Prof.. Roger Bonnet. (The full size version of the spacecraft is 32 metres across, so large that it would stretch the entire width of a football pitch. Almost 90 of this is accounted for by the giant solar panels which are needed to provide electrical power in the dark depths of the Solar System). "Rosetta is a mission of major scientific importance," said Prof. Bonnet. "It will build on the discoveries made by Giotto and confirm ESA's leading role in the exploration of the Solar System and the Universe as a whole." The timing of this event has been chosen to coincide with the London meeting of the Rosetta Science Working Team and the second Earth flyby of the now non-operational Giotto spacecraft. In addition, the opening of the British Museum's 'Cracking Codes' Exhibition, for which the Rosetta Stone is the centrepiece, is set to take place on 10 July. The Rosetta mission. Rosetta is the third Cornerstone in ESA's 'Horizon 2000' long-term scientific programme. It will be launched by Ariane 5 rocket from Kourou spaceport in French Guiana in January 2003. In order to gain sufficient speed to reach the distant comet, Rosetta will require gravity assists from the Earth (twice) and Mars. After swinging around Mars in May 2005, Rosetta will return to Earth's vicinity in October 2005 and October 2007 before heading away from the Sun towards Comet Wirtanen. As it bounces around the Solar System, Rosetta will also make two excursions into the main asteroid belt, where it will obtain the first close-up images and information on two contrasting objects, 4979 Otawara and 140 Siwa. Scientists believe Otawara is less than 20 km across, whereas Siwa is probably 110 km in diameter, much larger than any asteroid which has so far been visited by spacecraft. Rosetta will fly to within 1,000 km of Otawara in July 2006, followed by a similar rendezvous with Siwa two years later. However, the most difficult phase of the mission will be the final rendezvous with the fast-moving comet (the foreseen date for the rendezvous manoeuvre is 27 November 2011, close approach is set for 20 May 2012 and orbit insertion around the nucleus is set for 28 May 2012). Thus, after a 5.3 billion km space odyssey, Rosetta will make first contact with Wirtanen about 675 million km from the Sun. At this distance, sunlight is 20 times weaker than on Earth, and the comet's nucleus will still be frozen and inactive. Once the navigation team are able to determine the comet's exact location from images returned by the spacecraft camera, a series of braking manoeuvres will allow Rosetta to match speed and direction with its target. After about seven months of edging closer, Rosetta will eventually close to within 2 km of Wirtanen's frozen nucleus. From its close orbit above the tiny nucleus, Rosetta will be able to send back the most detailed images and information ever obtained of a comet. When a suitable landing site has been chosen, about a month after global mapping starts, the orbiter will release a 100 kg lander onto the comet's solid surface. Touchdown must be quite slow - less than one metre per second - to allow for the almost negligible gravitational pull of the tiny nucleus. In order to ensure that the lander does not bounce and disappear into space, an anchoring harpoon will be fired into the surface immediately on impact. By this time, the warmth of the Sun will probably have begun to vapourise parts of the nucleus, initiating some form of surface outgassing. For a period of about a month, data from the lander's eight experiments will be relayed to Earth via the orbiter. They will send back unique information on the nature and composition of the nucleus. Samples for chemical analysis will be taken of the organic crust and ices to a depth of at least 20 cm. Other instruments will measure characteristics such as near-surface strength, density, texture, porosity and thermal properties. Meanwhile, as Comet Wirtanen approaches the Sun, the Rosetta orbiter will fly alongside it, mapping its surface and studying changes in its activity. As its icy nucleus evaporates, 12 experiments on the orbiter will map its surface and study the dust and gas particles it ejects. For the first time, scientists will be able to monitor at close quarters the dramatic changes which take place as a comet plunges sunwards at a speed of 46,000 kph. The stream of data will include a mass of new information about the comet's changes in behaviour as it approaches the Sun, including: * variations in the temperature of the nucleus, * changing intensity and location of gas and dust jets on the nucleus, * the amount of gas and dust emitted from the nucleus, * the size, composition and impact velocity of dust particles, * the nature of the comet's interaction with the charged particles of the solar wind. By mission's end in July 2013, Rosetta will have spent almost two years chasing the comet for millions of kilometres through space. It will also have returned a treasure trove of data, which will enable us to learn more about how the planets formed and where we came from. Why Rosetta? Space exploration is all about discovering the unknown. Just as, 200 years ago, the discovery of the Rosetta Stone eventually enabled Champollion to unravel the mysteries of ancient Egyptian hieroglyphics, so Rosetta will help scientists to unravel the mysteries of comets. Hieroglyphics were the building blocks of the Egyptian language. Comets are the most primitive objects in the Solar System, the building blocks from which the planets formed. Virtually unchanged after 4.6 billion years in the deep freeze of the outer Solar System, they still contain ices and dust from the original solar nebula. They also contain complex organic compounds which some scientists believe may have been the first building blocks for life on Earth. 200 years ago, the discovery of a slab of volcanic basalt near the Egyptian town of Rashid (Rosetta) led to a revolution in our understanding of the past. By comparing the inscriptions on the 'Rosetta Stone', historians were able to decipher Egyptian hieroglyphics for the first time. Just as the Rosetta Stone provided the key to an ancient civilisation, so the European Space Agency's Rosetta spacecraft will allow scientists to unlock the mysteries of the oldest building blocks of our Solar System - the comets. The legacy of Giotto. For centuries, comets have inspired awe and wonder. Many ancient civilisations saw them as portents of death and disaster, omens of great social and political upheavals. Shrouded in thin, luminous veils with tails streaming behind them, these 'long-haired stars' were given the name 'comets' by the ancient Greeks (the Greek word kome meant 'hair'). When ESA's Giotto spacecraft arrived at Halley's Comet in 1986, no one knew what a comet nucleus was really like. The problem was that it is impossible to see the solid heart of a comet from the Earth. As soon as the nucleus moves close enough to us for detailed observation, it is obscured from view by a shroud of gas and dust. The most popular theory about the nature of comets was put forward by American astronomer Fred Whipple, who believed they were like dirty snowballs - large chunks of water ice and dust mixed with ammonia, methane and carbon dioxide. As they approach the Sun, their outer ices begin to vapourise, releasing large amounts of dust and gas to form the surrounding coma and wispy tails. Today, largely thanks to data from Giotto and the Russian Vega spacecraft, we now know that Whipple's model was fairly accurate. A comet nucleus resembles a fluffy snowball, usually only a few kilometres across, coated with a crust of black (probably organic) material and spouting jets of vapourised ice. However, despite these advances, scientists want to learn more about these occasional visitors to the inner Solar System. Why is it important to study comets? Comets formed about 4.5 billion years ago, and so they are among the oldest, most primitive objects in our Solar System. Billions of these giant chunks of ice still linger in the depths of space, the remnants of a vast swarm of objects which once surrounded our Sun and eventually came together to form planets. During the early history of our planet, the Solar System was like a gigantic shooting gallery with comets and asteroids continually crashing into the Earth. Some of the water which makes up the oceans may have originated in these ancient comet collisions. Previous studies have shown that comets carry complex organic molecules, compounds which are rich in carbon, hydrogen, oxygen and nitrogen. Intriguingly, these are the elements, which make up nucleic acids and amino acids, essential ingredients for life as we know it. Did life on Earth begin with the help of cometary seeding? If so, it almost certainly began in a similar way somewhere else. Fortunately, comets rarely strike the Earth today. One of the most recent episodes which has been linked to a small comet occurred at Tunguska in Siberia in 1908. When the incoming object exploded in mid-air, trees were flattened for hundreds of kilometres around. Rosetta's target is the periodic Comet Wirtanen, a chunk of dirty ice less than 1 km across which orbits the Sun once every 5 and a half years. Wirtanen was chosen for the mission because it is much easier to reach than most comets and its path is predictable. Since its discovery in 1948, it has been well observed by ground-based instruments, so its orbit is well known. In recent years the comet's orbit has been altered by the gravitational pull of Jupiter so that it passes close to the Earth's orbit and never strays too far from the Sun. After multiple approaches to the Sun, Wirtanen has lost most of its volatile ices, so outgassing activity remains quite low. This will make it easier for the instruments on board the Rosetta orbiter and lander to image and study the comet's surface.

Solar Electric Propulsion for Future NASA Missions

NASA Technical Reports Server (NTRS)

Landis, Geoffrey A.; Oleson, Steven R.; Mercer, Carolyn R.

2015-01-01

Use of high-power solar arrays, at power levels ranging from approximately 500 KW to several megawatts, has been proposed for a solar-electric propulsion (SEP) demonstration mission, using a photovoltaic array to provide energy to a high-power xenon-fueled engine. One of the proposed applications of the high-power SEP technology is a mission to rendezvous with an asteroid and move it into lunar orbit for human exploration, the Asteroid Retrieval mission. The Solar Electric Propulsion project is dedicated to developing critical technologies to enable trips to further away destinations such as Mars or asteroids. NASA needs to reduce the cost of these ambitious exploration missions. High power and high efficiency SEP systems will require much less propellant to meet those requirements.

OSIRIS-REx Touch-And-Go (TAG) Mission Design and Analysis

NASA Technical Reports Server (NTRS)

Berry, Kevin; Sutter, Brian; May, Alex; Williams, Ken; Barbee, Brent W.; Beckman, Mark; Williams, Bobby

2013-01-01

The Origins Spectral Interpretation Resource Identification Security Regolith Explorer (OSIRIS-REx) mission is a NASA New Frontiers mission launching in 2016 to rendezvous with the near-Earth asteroid (101955) 1999 RQ36 in late 2018. After several months in formation with and orbit about the asteroid, OSIRIS-REx will fly a Touch-And-Go (TAG) trajectory to the asteroid s surface to obtain a regolith sample. This paper describes the mission design of the TAG sequence and the propulsive maneuvers required to achieve the trajectory. This paper also shows preliminary results of orbit covariance analysis and Monte-Carlo analysis that demonstrate the ability to arrive at a targeted location on the surface of RQ36 within a 25 meter radius with 98.3% confidence.

A study of extended zodiacal structures

NASA Technical Reports Server (NTRS)

Sykes, Mark V.

1990-01-01

Observations of cometary dust trails and zodiacal dust bands, discovered by the Infrared Astronomical Satellite (IRAS) were analyzed in a continuing effort to understand their nature and relationship to comets, asteroids, and processes effecting those bodies. A survey of all trails observed by IRAS has been completed, and analysis of this phenomenon continues. A total of 8 trails have been associated with known short-period comets (Churyumov-Gerasimenko, Encke, Gunn, Kopff, Pons-Winnecke, Schwassmann-Wachmann 1, Tempel 1, and Tempel 2), and a few faint trails have been detected which are not associated with any known comet. It is inferred that all short-period comets may have trails, and that the trails detected were seen as a consequence of observational selection effects. Were IRAS launched today, it would likely observe a largely different set of trails. The Tempel 2 trail exhibits a small but significant excess in color temperature relative to a blackbody at the same heliocentric distance. This excess may be due to the presence of a population of small, low-beta particles deriving from large particles within the trail, or a temperature gradient over the surface of large trail particles. Trails represent the very first stage in the formation and evolution of a meteor stream, and may also be the primary mechanism by which comets contribute to the interplanetary dust complex. A mathematical model of the spatial distribution of orbitally evolved collisional debris was developed which reproduces the zodiacal dust band phenomena and was used in the analysis of dust band observations made by IRAS. This has resulted in the principal zodiacal dust bands being firmly related to the principal Hirayama asteroid families. In addition, evidence for the collisional diffusion of the orbital elements of the dust particles has been found in the case of dust generated in the Eos asteroid family.

Beginning Research with the 1.8-meter Spacewatch Telescope

NASA Technical Reports Server (NTRS)

Gehrels, Tom; Lane, Lynn A.

2001-01-01

The purpose of this grant was to bring the Spacewatch 1.8-m telescope to operational status for research on asteroids and comets. This objective was achieved; first light with the telescope was in May 2000 and since then several tests and demonstrations of the facility's capability to observe Earth-approaching Asteroids (EAs) have been made, including the first observations to be incorporated into a peer-reviewed publication. The Spacewatch 1.8-m telescope will be the largest in the world dedicated full time to finding and doing astrometry of asteroids and comets. It will be used to search for asteroids and comets anywhere from the space near Earth to regions beyond the orbit of Neptune, and to do astrometry and lightcurves on the fainter of such objects that are already known. Its comparatively large aperture will permit faster discovery of the very small asteroids in Earthlike orbits, such as 1998 KY(sub 26), that are coveted for their accessibility as material resources in space, as well as recovery of EAs on their return apparitions when they tend to be more distant and fainter than they were at the times of their discoveries. It will also tend to find EAs when they do not happen to be close to Earth. Discoveries made under those circumstances allow the objects to be followed for longer intervals, providing better determinations of their orbits during their discovery apparitions. In addition to its size, the 1.8-m Spacewatch telescope will have the unique capability of long strip scanning in any direction, for example along the ecliptic (the plane of the solar system), and along the line of variation of EAs with uncertain orbits that are being targeted for recovery.

Terrestrial production vs. extraterrestrial delivery of prebiotic organics to the early Earth

NASA Technical Reports Server (NTRS)

Chyba, C. F.; Sagan, C.; Thomas, P. J.; Brookshaw, L.

1991-01-01

A comprehensive treatment of comet/asteroid interaction with the atmosphere, ensuring surface impact, and resulting organic pyrolysis is required to determine whether more than a negligible fraction of the organics in incident comets and asteroids actually survived collision with Earth. Results of such an investigation, using a smoothed particle hydrodynamic simulation of cometary and asteroidal impacts into both oceans and rock, demonstrate that organics will not survive impacts at velocities approx. greater than 10 km s(exp -1), and that even comets and asteroids as small as 100m in radius cannot be aerobraked to below this velocity in 1 bar atmospheres. However, for plausible dense (10 bar CO2) early atmospheres, there will be sufficient aerobraking during atmospheric passage for some organics to survive the ensuing impact. Combining these results with analytical fits to the lunar impact record shows that 4.5 Gyr ago Earth was accreting at least approx. 10(exp 6) kg yr(exp 1) of intact cometary organics, a flux which thereafter declined with a approx. 100 Myr half-life. The extent to which this influx was augmented by asteroid impacts, as well as the effect of more careful modelling of a variety of conservative approximations, is currently being quantified. These results may be placed in context by comparison with in situ organic production from a variety of terrestrial energy sources, as well as organic delivery by interplanetary dust. Which source dominated the early terrestrial prebiotic inventory is found to depend on the nature of the early terrestrial atmosphere. However, there is an intriguing symmetry: it is exactly those dense CO2 atmospheres where in situ atmospheric production of organic molecules should be the most difficult, in which intact cometary organics would be delivered in large amounts.

Colour, albedo and nucleus size of Halley's comet

NASA Technical Reports Server (NTRS)

Cruikshank, D. P.; Tholen, D. J.; Hartmann, W. K.

1985-01-01

Photometry of Halley's comet in the B, J, V, and K broadband filters during a time when the coma was very weak and presumed to contribute negligibly to the broadband photometry is reported. The V-J and J-K colors suggest that the color of the nucleus of Halley's comet is similar to that of the D-type asteroids, which in turn suggests that the surface of the nucleus has an albedo less than 0.1.

A brief visit from a red and extremely elongated interstellar asteroid.

PubMed

Meech, Karen J; Weryk, Robert; Micheli, Marco; Kleyna, Jan T; Hainaut, Olivier R; Jedicke, Robert; Wainscoat, Richard J; Chambers, Kenneth C; Keane, Jacqueline V; Petric, Andreea; Denneau, Larry; Magnier, Eugene; Berger, Travis; Huber, Mark E; Flewelling, Heather; Waters, Chris; Schunova-Lilly, Eva; Chastel, Serge

2017-12-21

None of the approximately 750,000 known asteroids and comets in the Solar System is thought to have originated outside it, despite models of the formation of planetary systems suggesting that orbital migration of giant planets ejects a large fraction of the original planetesimals into interstellar space. The high predicted number density of icy interstellar objects (2.4 × 10 -4 per cubic astronomical unit) suggests that some should have been detected, yet hitherto none has been seen. Many decades of asteroid and comet characterization have yielded formation models that explain the mass distribution, chemical abundances and planetary configuration of the Solar System today, but there has been no way of telling whether the Solar System is typical of planetary systems. Here we report observations and analysis of the object 1I/2017 U1 ('Oumuamua) that demonstrate its extrasolar trajectory, and that thus enable comparisons to be made between material from another planetary system and from our own. Our observations during the brief visit by the object to the inner Solar System reveal it to be asteroidal, with no hint of cometary activity despite an approach within 0.25 astronomical units of the Sun. Spectroscopic measurements show that the surface of the object is spectrally red, consistent with comets or organic-rich asteroids that reside within the Solar System. Light-curve observations indicate that the object has an extremely oblong shape, with a length about ten times its width, and a mean radius of about 102 metres assuming an albedo of 0.04. No known objects in the Solar System have such extreme dimensions. The presence of 'Oumuamua in the Solar System suggests that previous estimates of the number density of interstellar objects, based on the assumption that all such objects were cometary, were pessimistically low. Planned upgrades to contemporary asteroid survey instruments and improved data processing techniques are likely to result in the detection of more interstellar objects in the coming years.

Pointing control for the International Comet Mission

NASA Technical Reports Server (NTRS)

Leblanc, D. R.; Schumacher, L. L.

1980-01-01

The design of the pointing control system for the proposed International Comet Mission, intended to fly by Comet Halley and rendezvous with Comet Tempel-2 is presented. Following a review of mission objectives and the spacecraft configuration, design constraints on the pointing control system controlling the two-axis gimballed scan platform supporting the science instruments are discussed in relation to the scientific requirements of the mission. The primary design options considered for the pointing control system design for the baseline spacecraft are summarized, and the design selected, which employs a target-referenced, inertially stabilized control system, is described in detail. The four basic modes of operation of the pointing control subsystem (target acquisition, inertial hold, target track and slew) are discussed as they relate to operations at Halley and Tempel-2. It is pointed that the pointing control system design represents a significant advance in the state of the art of pointing controls for planetary missions.

Meteorites, Bolides and Comets: A Tale of Inconsistency

NASA Astrophysics Data System (ADS)

Jakes, P.; Padevet, V.

1992-07-01

Inhomogeneity of cometary nuclei has been established through the observed disruptions of comets [1] and through the determination of dust particle composition during the encounter of the Vega and Giotto satellites with comet Halley [2,3,4]. The raisin bread model of cometary nuclei [5,6] assumes the presence of solid (rock) and dust particle material set in the volatile rich, ice- cemented material. Rock material may contribute to the formation of dust particles. Gombosi and Houpis [5] argued that only the composition of dust particles derived from the icy, volatile component of the comet were analyzed and implied thus that the third cometary component present (raisins/rocks) has not been examined. The compositions of the cometary (Halley) dust and the interplanetary dust particles (IDPs) are "chondritic" (Blanford et al., 1988). It is difficult, therefore to estimate the proportion of cometary to asteroid-derived dust in near Earth space, e.g., among the IDPs [7] unless other criteria are available. Bolide multistation photographic tracking allows the determination of the orbital preencounter parameters of solid bodies (0.01-100,000 kg in mass) with the Earth, and allows us to classify them according to their ablation coefficient (tau), penetration depth into the atmosphere (PE), theoretical densities (sigma), and terminal velocities (V(sub)E). Four groups are recognized (Table 1). Three of the type I bolides were recovered as ordinary chondrites (Pribram, Lost City, and Innisfree). Ceplecha [8] has shown that 38% of bolides (fireballs) come from cometary orbits (11% from highly eccentric orbits typical of new comets), but most of the bolides (62%) originate at asteroidal orbits. Seven of the 14 known meteoric showers could be attributed to known comets: N,S Taurids to 1970 P/Encke, Lyrids to 1861 I Thatcher-Beaker, Perseids to 1862 III Swift-Tuttle- Simons, Orionids to 1835 III P/Halley, Draconids to 1946 V P/Giacobini-Zinner, Leonids to 1966 I Tempel-Tuttle, and Leo Minorids to 1739 Zanotti. Geminids were related to asteroid 3200 Phaeton, considered to be an "extinct comet." Spurny [9], using ablation coefficient and penetration depth criteria, found that Geminids (frequently) and Taurids (rarely) contain bolides of types I and II. This may indicate that meteoric showers from "comets" on AAA orbits contain some portion of "rocky" material comparable to chondrites. These observations revive Opik's (1963) idea that comets may be captured in the asteroid belt on AAA orbits and may contain (and supply) chondritic meteorites to the Earth [10]. If the relationship among large solid particles "native to the asteroid belt" and those from the outer solar system can be established, they can be scaled and applied to IDPs. We have studied the records of 292 bolides (Prairie and European networks) with measured terminal velocities. We attempt to use the terminal velocity, calculated density, estimated terminal mass, and mechanical strength to correlate features with the meteorite features. We compare the meteorite fall frequency [11] with the bolide features. Two extreme hypotheses (Table 1) are examined: (A) bolides of types IIIa and IIIb do not have equivalents among the meteorites and (B) all four bolide types have meteoritic equivalents, and only IDPs do not produce bolides (fireballs). If the entry parameters of meteoroids are similar, bodies with lower density should reach terminal velocity at higher altitudes than those with higher density. If it is assumed that fragmentation is the same for dense (I and II) and less dense bodies (IIIa and IIIb), the calculated terminal altitudes show that among the bolides exist materials with lower densities than those of recovered meteorites and that model A of the correlation between meteorite falls and bolide observations is likely [12]. If, however, the less dense bodies were more easily fragmented than denser bodies, the correlation is better for hypothesis B. Table 1, which in the hard copy appears here, shows fireball observations. Using the value of terminal velocities and the average value of ablation coefficients the terminal (residual) masses (m(sub)E) can be calculated. Among the bodies studied, 99 were heavier than 0.1 kg and 153 heavier than 0.01 kg. The parameter (m(sub)E) indicates the end of ablation in the atmosphere, but it cannot distinguish between meteoroids that were totally disintegrated and those genuinely decelerated. Similarly the calculated terminal altitudes and mechanical strength values do not provide a unequivocal interpretation. Correlation of bolide properties with meteorite falls could well be accommodated by the hypothesis B in which each bolide type has a meteorite equivalent. This has, however, some "outrageous" implications: comets may carry chondrites, icy dust balls do not produce fireballs; the extremely primitive carbon-rich particles represented by the IDPs do not form larger discrete bodies (fireballs) of "asteroidal" size; and the asteroid belt is a mixture of "native fractionated old bodies" together with the captured comets. Hypothesis B therefore contradicts the "established" scheme of the asteroid belt in which the non-differentiated meteorites (CI, CM, and CV) form the outer part of the asteroid belt, whereas the fractionated metamorphosed and igneous meteorites characterize the inner asteroids. References: [1] Whipple F. L., 1987, Phil. Trans. R. Soc. Lond., A 323, 339. [2] Dikov Yu. P. et al., 1991, Geochemistry International, 29, 33-38. [3] Kissel J., et al., 1986, Nature, 321, 326. [4] Solc M., et al., 1987, Publ. Astr. Inst. Czechosl., 67, 47. [5] Gombosi T. I. and Houpis H. L. F., 1986, Nature, 324, 43. [6] Delsemme A. H., 1977, Comets, asteroids, meteorites, Univ. of Toledo Press. [7] Gibson E. K., 1992, J. Geophys. Res., 97, E3 3865. [8] Ceplecha Z., 1988, Bull. Astr. Inst. Czech., 39, 221. [9] Spurny P., 1991, doc. diss., Astr. Inst. Czechosl. [10] Opik E. J., 1963, Adv. Astr. Astrophys., 2, 219. [11] Hutchinson R., et al., 1977, Appendix to Catalogue of Meteorites, British Museum, London. [12] Ceplecha Z. and McCrosky R. E., 1976, J. Geophys. Res., 81, 6257.

A Secondary Ion Mass Analyzer for Remote Surface Composition Analysis of the Galilean Moons

NASA Technical Reports Server (NTRS)

Krueger, H.; Srama, R.; Johnson, T. V.; Henkel, H.; vonHoerner, H.; Koch, A.; Horanyi, M.; Gruen, E.; Kissel, J.; Krueger, F.

2003-01-01

Galileo in-situ dust measurements have shown that the Galilean moons are surrounded by tenuous dust clouds formed by collisional ejecta from their icy surfaces, kicked up by impacts of interplanetary micrometeoroids. The majority of the ejecta dust particles have been sensed at altitudes below five between 0.5 and 1 micron, just above the detector threshold, indicating a size distribution decreasing towards bigger particles. their parent bodies. They carry information about the properties of the surface from which they have been kicked up. In particular, these grains may carry organic compounds and other chemicals of biological relevance if they exist on the icy Galilean moons. In-situ analysis of the grain composition with a sophisticated dust analyzer instrument flying on a Jupiter Icy Moons Orbiter can provide important information about geochemical and geophysical processes during the evolutionary histories of these moons which are not accessible with other techniques from an orbiter spacecraft. Thus, spacecraft-based in-situ dust measurements can be used as a diagnostic tool for the analysis of the surface composition of the moons. This way, the in-situ measurements turn into a remote sensing technique by using the dust instrument like a telescope for surface investigation. An instrument capable of very high resolution composition analysis of dust particles is the Cometary Secondary Ion Mass Analyzer (COSIMA). The instrument was originally developed for the Comet Rendezvous and Asteroid Flyby (CRAF) mission and has now been built for ESA'S comet orbiter Rosetta. Dust particles are collected on a target and are later located by an optical microscope camera. A pulsed primary indium ion gun partially ionizes the dust grains. The generated secondary ions are accelerated in an electric field and travel through a reflectron-type time-of-flight ion mass spectrometer.

Characterizing the population of Asteroids in Cometary Orbits (ACOs)

NASA Astrophysics Data System (ADS)

Tancredi, Gonzalo; Licandro, Javier; Alí-Lagoa, Victor; Martino, Silvia; Vieira Monteiro, Filipe; Silva, Jose Sergio; Lazzaro, Daniela

2015-08-01

The classification criterion between asteroids and comets has evolved in recent decades, but the main phenomenological distinction remains unchanged: comets are active objects as they present gas and dust ejection from the surface at some point of their orbits, while asteroids are inert objects as they do not show any kind of large scale gas and dust ejection.To identify the transitional objects several classification schemes based on the orbital elements have been used. They are usually based on the Tisserand’s parameter (TJ). Tancredi (2014) presents a much more restrictive criterion to identify ACOs that ensured that the objects have a dynamical evolution similar to the population of periodic comets. After applying the criteriaa to the sample of over half a million asteroids already discovered, we obtain 316 ACOs that are further classified in subclasses similar to the cometary classification: 203 objects belong to the Jupiter Family group; 72 objects are classified as Centaurs; and 56 objects have Halley Type Orbits (also known as Damocloids). These are the best-known extinct/dormant comets candidates from a dynamical point of view.We study the physical properties of this sample of ACOs. Two results will be presented:- We look for the ACOs detected by the NASA’s WISE and by fitting a thermal model to their observations, we derive: the effective diameter, beaming parameter and the visible geometric albedo, using the method described in Al-Lagoa et al (2013). We obtain these parameters for 37 of 203 ACOs in JFC orbits and 13 of 56 Damocloids. We also compute the Cumulative Size Distribution (CSDs) of these populations and compare them with the CSDs of JF Comets and Centaurs.- We have been monitoring the observable ACOs since 12/2014 up to 06/2015. Every other month we select all the ACOs with elongations >90deg and estimated magnitudes V<21. We try to observe them with the 1m IMPACTON telescope of the Observatório Astronômico do Sertão de Itaparica (OASI). By comparing the photometric profiles of the ACOs with background stars, we try to detect some hint of cometary activity. Over 20 ACOs have been observed in the six months.

Clementine Observations of the Zodiacal Light and the Dust Content of the Inner Solar System

NASA Technical Reports Server (NTRS)

Hahn, Joseph M.; Zook, Herbert A.; Cooper, Bonnie; Sunkara, Bhaskar

2002-01-01

Using the Moon to occult the Sun, the Clementine spacecraft used its navigation cameras to map the inner zodiacal light at optical wavelengths over elongations of 3 approx. less than epsilon approx. less than 30 deg from the Sun. This surface brightness map is then used to infer the spatial distribution of interplanetary dust over heliocentric distances of about 10 solar radii to the orbit of Venus. The averaged ecliptic surface brightness of the zodiacal light falls off as Z(epsilon) is a member of epsilon(sup -2.45 +/- 0.05), which suggests that the dust cross-sectional density nominally falls off as sigma(r) is a member of r(sup - 1.45 +/- 0.05). The interplanetary dust also has an albedo of alpha approx. = 0.1 that is uncertain by a factor of approx. 2. Asymmetries of approx. 10% are seen in directions east-west and north-south of the Sun, and these may be due the giant planets' secular gravitational perturbations. We apply a simple model that attributes the zodiacal light as due to three dust populations having distinct inclination distributions, namely, dust from asteroids and Jupiter-family comets (JFCs) having characteristic inclinations of i approx. 7 deg, dust from Halley-type comets having i approx. 33 deg, and an isotropic cloud of dust from Oort Cloud comets. The best-fitting scenario indicates that asteroids + JFCs are the source of about 45% of the optical dust cross section seen in the ecliptic at 1 AU but that at least 89% of the dust cross section enclosed by a 1-AU-radius sphere is of a cometary origin. Each population's radial density variations can also deviate somewhat from the nominal sigma(r) is a member of r(sup -1.45). When these results are extrapolated out to the asteroid belt, we find an upper limit on the mass of the light-reflecting asteroidal dust that is equivalent to a 12-km asteroid, and a similar extrapolation of the isotropic dust cloud out to Oort Cloud distances yields a mass equivalent to a 30-km comet, although the latter mass is uncertain by orders of magnitude.

Using Chebyshev polynomial interpolation to improve the computational efficiency of gravity models near an irregularly-shaped asteroid

NASA Astrophysics Data System (ADS)

Hu, Shou-Cun; Ji, Jiang-Hui

2017-12-01

In asteroid rendezvous missions, the dynamical environment near an asteroid’s surface should be made clear prior to launch of the mission. However, most asteroids have irregular shapes, which lower the efficiency of calculating their gravitational field by adopting the traditional polyhedral method. In this work, we propose a method to partition the space near an asteroid adaptively along three spherical coordinates and use Chebyshev polynomial interpolation to represent the gravitational acceleration in each cell. Moreover, we compare four different interpolation schemes to obtain the best precision with identical initial parameters. An error-adaptive octree division is combined to improve the interpolation precision near the surface. As an example, we take the typical irregularly-shaped near-Earth asteroid 4179 Toutatis to demonstrate the advantage of this method; as a result, we show that the efficiency can be increased by hundreds to thousands of times with our method. Our results indicate that this method can be applicable to other irregularly-shaped asteroids and can greatly improve the evaluation efficiency.

The study of the physics of cometary nuclei

NASA Technical Reports Server (NTRS)

Whipple, Fred L.

1987-01-01

The numerical calculations of stability for many possible orbits of the double nucleus for P/Holmes showed that the likelihood of such a precollision history was quite high. A number of investigations were made of hypothetical orbits for particles about the asteroid Amphitrite to test for stability. The purpose was to establish more favorable fly-by orbits close to the asteroid for the Galileo missions en-route to Jupiter, reducing the collisional hazards. A statistical study was made of the orbits of long-period comets with small original semi-major axes recently perturbed from the great Opik-Oort Cloud. The results from the space missions to Halley's comet are partially reported in the two papers in the appendices.

Evaluation of radioisotope electric propulsion for selected interplanetary science missions

NASA Technical Reports Server (NTRS)

Oh, David; Bonfiglio, Eugene; Cupples, Mike; Belcher, Jeremy; Witzberger, Kevin; Fiehler, Douglas; Robinson Artis, Gwen

2005-01-01

This study assessed the benefits and applicability of REP to missions relevant to the In-Space Propulsion Program (ISPP) using first and second generation RPS with specific powers of 4 We/kg and 8 We/kg, respectively. Three missions representing small body targets, medium outer planet class, and main belt asteroids and comets were evaluated. Those missions were a Trojan Asteroid Orbiter, Comet Surface Sample Return (CSSR), and Jupiter Polar Orbiter with Probes (JPOP). For each mission, REP cost and performance was compared with solar electric propulsion system (SEPS) and SOA chemical propulsion system (SCPS) cost and performance. The outcome of the analysis would be a determinant for potential inclusion in the ISPP investment portfolio.

Mitigation of Earth-asteroid collisions via explosive, intense radiation sources

NASA Astrophysics Data System (ADS)

Miles, Aaron; Sanders, James

2005-10-01

The Universe is continually producing astrophysical explosions that generate intense bursts of electromagnetic and particle radiation. Interaction of this radiation with nearby objects can effect significant changes to their dynamics through a variety of processes including ionization, ablation, and shock generation. The next time a large asteroid or comet is found to be approaching the Earth on an impact trajectory, humans may find it prudent to mimic nature by using the most intense radiation sources available to alter the incoming object's trajectory and avert a catastrophic collision. With this in mind, we consider the effect of nuclear explosives on nearby would-be Earth impactors. Neutrons and x-rays produced in the explosion are deposited in a thin layer of the asteroid's surface, resulting in ablation and shock and thereby imparting a deflection velocity. A Monte Carlo code is used for radiation transport and energy deposition, while the subsequent dynamic evolution of the asteroid is followed with the hydrodynamics code CALE. We consider the dependence of the deflection velocity on the source energy and spectrum, the asteroid or comet composition, and the standoff distance between the target and the source. This work was performed under the auspices of the U. S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.

Solar System Research with the Spacewatch 1.8-m Telescope

NASA Technical Reports Server (NTRS)

McMillan, Robert S.

2001-01-01

During this grant period, the 1.8-m Spacewatch telescope was put into routine operation to search for asteroids and comets ranging in location from near-Earth space to regions beyond the orbit of Neptune. All of these classes of objects can be detected simultaneously with our uniform scanning procedures. We are studying near Earth objects (NEOs), main belt asteroids, comets, Centaurs, and trans-Neptunian objects (TNOs), as well as the interrelationships of these classes and their bearing on the origin and evolution of the solar system. The Spacewatch 1.8-meter telescope is sensitive to V(mag) < 22.6 in sidereal scanning mode and is able to reach even fainter in longer 'staring' exposures, with a field of view 0.5 degrees square. These faint limits make the operation of the Spacewatch 1.8-m telescope complementary to asteroid surveys being done by other groups. Specifically, EAs smaller than 100 m in diameter and small main belt asteroids can be found, as well as more distant objects such as Centaurs/Scattered Disk Objects (SDOs) and TNOs. The 1.8-m telescope is also being used to do recoveries and astrometry of recently-discovered asteroids that subsequently become too faint for the other groups before good orbits are established.

Search techniques for near-earth asteroids

NASA Technical Reports Server (NTRS)

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

1990-01-01

Knowledge of the near-earth asteroids (Apollo, Amor, and Aten groups) has increased enormously over the last 10 to 15 years. This has been due in large part to the success of programs that have systematically searched for these objects. These programs have been motivated by the apparent relationships of the near-earth asteroids to terrestrial impact cratering, meteorites, and comets, and their relative accessibility for asteroid missions. Discovery of new near-earth asteroids is fundamental to all other studies, from theoretical modeling of their populations to the determination of their physical characteristics by various remote-sensing techniques. The methods that have been used to find these objects are reviewed, and ways in which the search for near-earth asteroids can be expanded are discussed.

Epsilon Eridani Inner Asteroid Belt

NASA Image and Video Library

2017-09-14

SCI2017_0004: Artist's illustration of the Epsilon Eridani system showing Epsilon Eridani b, right foreground, a Jupiter-mass planet orbiting its parent star at the outside edge of an asteroid belt. In the background can be seen another narrow asteroid or comet belt plus an outermost belt similar in size to our solar system's Kuiper Belt. The similarity of the structure of the Epsilon Eridani system to our solar system is remarkable, although Epsilon Eridani is much younger than our sun. SOFIA observations confirmed the existence of the asteroid belt adjacent to the orbit of the Jovian planet. Credit: NASA/SOFIA/Lynette Cook

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

The Trojan asteroids, located at Jupiter's L4 and L5 Lagrange points, are a potential source of insights into long-standing questions on the origin and early history of the Solar System. The 2013 Planetary Science Decadal Survey recommends a Trojan Tour and Rendezvous mission as high-priority among medium-class missions. A dedicated mission to the Trojan asteroids could confirm or refute multiple theories to correctly explain the Trojan asteroids' current location, characteristics, and behavior. In-depth and conclusive evidence for the Trojan asteroids' internal and external make-up as well as dynamical behavior hav been challenging due to limitations of ground- and space-based observations. Notwithstanding these limitations, it has been inferred that there are two distinct sub- populations that are distinguishable in visible and near-infrared spectra (redder and less red) within the swarms. These spectral groupings have not yet been conclusively linked to physical characteristics (e.g. size) or other observed parameters (e.g. albedo) of the primordial bodies. NASA's Jet Propulsion Laboratory's concept studies for Decadal Survey evaluated three concepts for missions to Trojan asteroids: each utilizing chemical- solar-electric, and radioisotope-electric for propulsion. Both Solar and Advanced Stirling Radioisotope Generators were considered for power [2]. We present a new conceptual mission to explore the Trojan asteroids that achieves the science goals prioritized in the 2013 Planetary Science Decadal Survey. The proposed mission aims to study both a redder and less red asteroid for the surface mineralogical and elemental composition, state of surface regolith, evidence and consequences of external modification processes such as collisional evolution, space weathering, and irradiation. Some potential targets in the L4 Greek camp currently under consideration for this mission include Achilles, Hektor and Agamemnon (redder) and Eurybates, Deipylos and Kalchas (less 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.

The ABC of ACM: asteroids, Buffon and comets

NASA Astrophysics Data System (ADS)

Steel, D. I.

1997-12-01

Most of the participants in the ACM 96 conference would have made use of facilities in a building named for Georges-Louis Leclerc, the Compte de Buffon (1707-1788). Buffon made many major contributions to the natural sciences, and may be considered to be one of the founders of planetary science. He proposed a theory for the origin of the planets which involved a massive comet having an oblique impact upon the Sun, the ejected material condensing so as to form a regular system of planets. Amongst his mathematical contributions is what is known as Buffon's Needle, whereby experimental evaluations of π may be made by randomly dropping a needle onto a set of parallel lines of separation greater than the needle length, and accumulating the fraction of times that the needle cuts one of the lines. Near-Earth asteroid (NEA) trails imaged onto a CCD chip provide a two-dimensional analogue of this, and where the pixel size is very large (this having some advantages for NEA searching) an analysis based on Buffon's Needle provides probabilities of the NEA trail lying within one, two or three pixels, such probabilities affecting the chances of detection. It is therefore appropriate that Buffon and his contributions to studies of comets and asteroids be remembered in these conference proceedings.

Comet/Asteroid Protection System: Concept Study Executive Summary

NASA Technical Reports Server (NTRS)

Mazanek, Daniel D.

2005-01-01

Many of the major issues have been identified for a futuristic capability to protect against impacting comets and asteroids, and a preliminary space-based concept has been envisioned. Some of the basic concept elements, approaches, methodologies, and features have been identified. When contemplating the ability to monitor comets and asteroids continuously, there are many trade-offs between orbiting observatories and detection systems on planetary bodies without an atmosphere. Future orbit modification techniques have the potential for rapid and controlled alteration of NEO orbits, provided that high-power, compatible thermal management systems are developed. Much additional work and analysis are required to identify a final system concept, and many trade studies need to be performed to select the best mix of system capability, reliability, maintainability, and cost. Finally, it is fully appreciated that at the present time space systems are much more costly than terrestrial-based systems. Hopefully, this will change in the future. Regardless, understanding what it would take to defend against a much wider range of the impact threat will foster ideas, innovations, and technologies that could one day enable the development of such a system. This understanding is vital to provide ways of reducing the costs and quantifying the benefits that are achievable with a system like CAPS.

Cometary delivery of organic molecules to the early earth

NASA Technical Reports Server (NTRS)

Chyba, Christopher F.; Thomas, Paul J.; Sagan, Carl; Brookshaw, Leigh

1990-01-01

It has long been speculated that earth accreted prebiotic organic molecules important for the origins of life from impacts of carbonaceous asteroids and comets during the period of heavy bombardment 4.5 x 10 to the 9th to 3.8 x 10 to the 9th years ago. A comprehensive treatment of comet-asteroid interaction with the atmosphere, surface impact, and resulting organic pyrolysis demonstrates that organics will not survive impacts at velocities greater than about 10 kilometers per second and that even comets and asteroids as small as 100 meters in radius cannot be aerobraked to below this velocity in 1-bar atmospheres. However, for plausible dense (10-bar carbon dioxide) early atmospheres, it is found that 4.5 x 10 to the 9th years ago earth was accreting intact cometary organics at a rate of at least about 10 to the 6th to 10 to the 7th kilograms per year, a flux that thereafter declined with a half-life of about 10 to the 8th years. These results may be put in context by comparison with terrestrial oceanic and total biomasses, about 3 x 10 to the 12th kilograms and about 6 x 10 to the 14th kilograms, respectively.

The solar panels of the spacecraft Stardust are deployed before undergoing lighting test in the PHSF

NASA Technical Reports Server (NTRS)

1999-01-01

In the Payload Hazardous Servicing Facility, workers look over the solar panels on the Stardust spacecraft that are deployed for lighting tests. Stardust is scheduled to be launched aboard a Boeing Delta II rocket from Launch Pad 17A, Cape Canaveral Air Station, on Feb. 6, 1999, for a rendezvous with the comet Wild 2 in January 2004. Stardust will use a substance called aerogel to capture comet particles flying off the nucleus of the comet, plus collect interstellar dust for later analysis. The collected samples will return to Earth in a sample return capsule to be jettisoned as it swings by Earth in January 2006.

JPL's On-Line Solar System Data Service

NASA Astrophysics Data System (ADS)

Giorgini, J. D.; Yeomans, D. K.; Chamberlin, A. B.; Chodas, P. W.; Jacobson, R. A.; Keesey, M. S.; Lieske, J. H.; Ostro, S. J.; Standish, E. M.; Wimberly, R. N.

1996-09-01

Numerous data products from the JPL ephemeris team are being made available via an interactive telnet computer service and separate web page. For over 15,000 comets and asteroids, 60 natural satellites, and 9 planets, users with an Internet connection can easily create and download information 24 hours a day, 7 days a week. These data include customized, high precision ephemerides, orbital and physical characteristics, and search-lists of comets and asteroids that match combinations of up to 39 different parameters. For each body, the user can request computation of more than 70 orbital and physical quantities. Ephemerides output can be generated in ICRF/J2000.0 and FK4/1950.0 reference frames with TDB, TT, or UTC timescales, as appropriate, at user specified intervals. Computed tables are derived from the same ephemerides used at JPL for radar astronomy and spacecraft navigation. The dynamics and computed observables include relativistic effects. Available ephemeris time spans currently range from A.D. 1599-2200 for the planets to a few decades for the satellites, comets and asteroids. Information on the interference from sunlight and moonlight is available. As an example of a few of the features available, we note that a user could easily generate information on satellite and planetary magnitudes, illuminated fractions, and the planetographic longitudes and latitudes of their centers and sub-solar points as seen from a particular observatory location on Earth. Satellite transits, occultations and eclipses are available as well. The resulting ASCII tables can be transferred to the user's host computer via e-mail, ftp, or kermit protocols. For those who have WWW access, the telnet solar system ephemeris service will be one feature of the JPL solar system web page. This page will provide up-to-date physical and orbital characteristics as well as current and predicted observing opportunities for all solar system bodies. Close Earth approaches and radar observations will be provided for comets and asteroids.

Cosmic impact: What are the odds?

NASA Astrophysics Data System (ADS)

Harris, A. W.

2009-12-01

Firestone et al. (PNAS 104, 16016-16021, 2007) propose that the impact of a ~4 km diameter comet (or multiple bodies making up a similar mass) led to the Younger Dryas cooling and extinction of megafauna in North America, 12,900 years ago. Even more provocatively, Firestone et al. (Cycle of Cosmic Catastrophes, Bear & Co. Books, 2006, 392pp), suggest that a nearby supernova may have produced a comet shower leading to the impact event, either by disturbing the Oort Cloud or by direct injection of 4-km comet-like bodies to the solar neighborhood. Here we show: (a) A supernova shockwave or mass ejection is not capable of triggering a shower of comets from the Oort Cloud. (b) An Oort Cloud shower from whatever cause would take 100,000 years or more for the perturbed comets to arrive in the inner solar system, and the peak flux would persist for some hundreds of thousands more years. (c) Even if all 20 solar masses or so of ejected matter from a SN were in the form of 4-km diameter balls, the probability of even one such ball hitting the Earth from an event 100 light years away would be about 3e-5. (d) A 4-km diameter ball traveling fast enough to get here from 100 LY away in some tens of thousands of years would deliver the energy of a 50 km diameter impactor traveling at typical Earth-impact velocity (~20 km/sec). We review the current impact flux on the Earth from asteroids and comets, and show that the probability of an impact of a 4-km diameter asteroid in an interval of 13,000 years is about one in a thousand, and the probability of a comet impact of that size is a few in a million. An "impact shower" caused by the injection or breakup of comets or asteroids in the inner solar system by whatever means would take tens to hundreds of thousands of years to clear out, thus the population of NEOs we see now with our telescopic surveys is what we’ve had for the last few tens of thousands of years, at least. Faced with such low odds, the evidence that such a large cosmic impact is the cause of the Younger Dryas boundary and cooling, and that there is no other possible cause, needs to be extraordinary indeed.

Amateur astronomers in support of observing campaigns

NASA Astrophysics Data System (ADS)

Yanamandra-Fisher, P.

2014-07-01

The Pro-Am Collaborative Astronomy (PACA) project evolved from the observational campaign of C/2012 S1 or C/ISON. The success of the paradigm shift in scientific research is now implemented in other comet observing campaigns. While PACA identifies a consistent collaborative approach to pro-am collaborations, given the volume of data generated for each campaign, new ways of rapid data analysis, mining access, and storage are needed. Several interesting results emerged from the synergistic inclusion of both social media and amateur astronomers: - the establishment of a network of astronomers and related professionals that can be galvanized into action on short notice to support observing campaigns; - assist in various science investigations pertinent to the campaign; - provide an alert-sounding mechanism should the need arise; - immediate outreach and dissemination of results via our media/blogger members; - provide a forum for discussions between the imagers and modelers to help strategize the observing campaign for maximum benefit. In 2014, two new comet observing campaigns involving pro-am collaborations have been identified: (1) C/2013 A1 (C/Siding Spring) and (2) 67P/Churyumov-Gerasimenko (CG). The evolving need for individual customized observing campaigns has been incorporated into the evolution of PACA (Pro-Am Collaborative Astronomy) portal that currently is focused on comets: from supporting observing campaigns for current comets, legacy data, historical comets; interconnected with social media and a set of shareable documents addressing observational strategies; consistent standards for data; data access, use, and storage, to align with the needs of professional observers. The integration of science, observations by professional and amateur astronomers, and various social media provides a dynamic and evolving collaborative partnership between professional and amateur astronomers. The recent observation of comet 67P, at a magnitude of 21.2, from Siding Spring, Australia, via robotic telescope network, also detected several asteroids in a crowded star field (SSI, Press Release, May 2014). These may be useful in support of the ESA/Gaia mission, which will characterize asteroids and comets to a magnitude of 20. While its network of amateur astronomers has already been established (Thuillot, 2005, ESASP, 576), such observations by robotic telescope networks can provide both astrometry and subsequent science analysis of the data acquired. An additional benefit of amateur network will be to unequivocally recognize asteroids and comets via complementary imaging that is not possible for the mission itself.

Comets, Asteroids, and the Origin of the Biosphere

NASA Technical Reports Server (NTRS)

Hoover, Richard B.

2006-01-01

During the past few decades, the role of comets in the delivery of water, organics, and prebiotic chemicals to the Biosphere of Earth during the Hadean (4.5-3.8 Ga) period of heavy bombardment has become more widely accepted. However comets are still largely regarded as frigid, pristine bodies of protosolar nebula material that are entirely devoid of liquid water and consequently unsuitable for life in any form. Complex organic compounds have been observed comets and on the water rich asteroid 1998 KY26, which has color and radar reflectivity similar to the carbonaceous meteorites. Near infrared observations have indicated the presence of crystalline water ice and ammonia hydrate on the large Kuiper Belt object (50000) Quaoar with resurfacing that may indicate cryovolcanic outgassing and the Cassini spacecraft has detected water-ice geysers on Saturn s moon Enceladus. Spacecraft observations of the chemical compositions and characteristics of the nuclei of several comets (Halley, Borrelly, Wild 2, and Tempel 1) have now firmly established that comets contain a suite of complex organic chemicals; water is the predominant volatile; and that extremely high temperatures (approx.350-400 K) can be reached on the surface of the very black (albedo-0.03) nuclei when the comets are with 1.5 AU from the Sun. Impact craters and pinnacles observed on comet Wild 2 suggest a thick crust and episodic outbursts and jets observed on the nuclei of several comets are interpreted as indications that localized regimes of liquid water and water vapor can periodically exist beneath the crust of some comets. The Deep Impact observations indicate that the temperature on the nucleus of of comet Tempel 1 at 1.5 AU varied from 330K on the sunlit side to a minimum of 280+/-8 K. It is interesting that even the coldest region of the comet surface was slightly above the ice/liquid water phase transition temperature. These results suggest that pools and films of liquid water can exist in a wide range of temperatures in cavities and voids at different depths just beneath the crust of a comet. The possibility that liquid water may exist over a wide range of temperatures on comets significantly enhances the possibility that these bodies may harbor niches suitable for microbial communities and ecosystems. Such niches would by ideal for the growth of psychrophilic, mesophilic, and possibly even thermophilic chemolithotrophs and photoautotrophs such as the motile filamentous cyanobacteria (e.g., Calothrix, Oscillatoria, Phormidium, and Spirulina) that can grow in geothermal springs and geysers at temperatures ranging from 320K to 345K and in cold polar desert soils. This paper reviews the observational data in support of the hypothesis that liquid water can exist in permafrost-like active regions just beneath the surface of comets when near perihelion and provides additional arguments in support of the hypothesis that comets, carbonaceous meteorites, and asteroids may have played a significant role in the origin and evolution of the Biosphere and in the distribution of microbial life throughout the Solar System.

The Ion Propulsion System for the Asteroid Redirect Robotic Mission

NASA Technical Reports Server (NTRS)

Herman, Daniel A.; Santiago, Walter; Kamhawi, Hani; Polk, James E.; Snyder, John Steven; Hofer, Richard; Sekerak, Michael

2016-01-01

The Asteroid Redirect Robotic Mission is a Solar Electric Propulsion Technology Demonstration Mission (ARRM) whose main objectives are to develop and demonstrate a high-power solar electric propulsion capability for the Agency and return an asteroidal mass for rendezvous and characterization in a companion human-crewed mission. This high-power solar electric propulsion capability, or an extensible derivative of it, has been identified as a critical part of NASA's future beyond-low-Earth-orbit, human-crewed exploration plans. This presentation presents the conceptual design of the ARRM ion propulsion system, the status of the NASA in-house thruster and power processing development activities, the status of the planned technology maturation for the mission through flight hardware delivery, and the status of the mission formulation and spacecraft acquisition.

Comets 169P/NEAT and P/2003 T12 (SOHO): Two possible fragments of a common ancestor?

NASA Astrophysics Data System (ADS)

Sosa, Andrea; Fernández, Julio Angel

2015-08-01

In a recent work we analyzed the orbit evolution of Jupiter family comets in near-Earth orbits, and found some comets moving on highly stable orbits, like the near-Earth asteroids (Fernández & Sosa 2015). Two of them actually show almost identical orbits; they are the comets 169P/NEAT and P/2003 T12 (SOHO). Comet 169P seems to be a few km-sized, almost inactive body, while P/2003 T12 would be a very small comet, with a sub-km radius nucleus. We performed extended orbital integrations for the past 100,000 yr to further study their dynamical evolution. We found that the orbital parameters remain stable for several thousand years, with a well defined absolute minimum of their relative spatial distance around 2900 yr in the past, coincident with a low value of the relative velocity. This spatial minimum is in a remarkable good agreement with the results obtained by means of other methods to study common origins between pairs of asteroids (Vokrouhlicky & Nesvorny 2008, Southworth & Hawkins 1963), and to test a comet-meteor shower association (Drummond 1981). Our results support the hypothesis of a breakup of a parent body, that ocurred about 2900 yr ago, as the most probable origin for the studied pair of comets. Possible fragmentation mechanisms, like thermal stress, rotational instability, or colisions, are briefly discussed.References:Drumond J.D. 1981. Icarus 45, 545-553.Fernández J.A., & Sosa A. 2015. Submitted to Planetary & Space Science.Southworth R.B., & Hawkins, G.S. 1963. Smithson. Contrib. Astrophys. 7, 261-285Vokrouhlicky D., & Nesvorny D. 2008. Astron. J. 136, 280-290.

Cometary Defense with Directed Energy

NASA Astrophysics Data System (ADS)

Zhang, Q.; Lubin, P. M.; Hughes, G. B.

2016-12-01

Cometary impacts pose a long-term hazard to humans on Earth. Due to their comparative rarity, most planetary defense schemes neglect the comet threat, choosing instead to focus exclusively on mitigating asteroid impacts. Methods like kinetic impactors may be suitable for deflecting near-Earth asteroids (NEAs) and Jupiter-family comets (JFCs), both of which are characterized by low inclination orbits and short orbital periods which favor early detection—characteristics ideal for an interception mission. In contrast, Halley-type comets (HTCs) and long-period comets (LPCs) are often found in high inclination orbits rarely more than 2 yr prior to reaching Earth's orbit. Unless discovered and identified in a prior apparition—often centuries or millennia earlier, if ever—timely interception of a threatening HTC or LPC is improbable even with preparation, with missions demanding delta-v budgets often in excess of 30 km/s. Active comets, however, are already naturally perturbed from purely gravitational trajectories through solar-driven sublimation of volatiles. Further deflection may be achieved by supplementing the solar radiation with an artificial directed energy source such as by one or more laser arrays positioned on or near Earth. Simulations were developed with models derived from the known solar nongravitational perturbations of typical comets. Results suggest that a diffraction-limited 500 m array operating at 10 GW for 10 min/day may be sufficient to divert a typical active 500 m comet from an impact given 1 yr. A larger 1 km array operating at 100 GW for 100 s/day is similarly effective. Care must be taken to ensure the target remains intact throughout the deflection period due to comets' low compressive strength and resulting propensity for disintegration at high incident flux.

NASA's Hubble Sees Asteroid Spout Six Comet-like Tails

NASA Image and Video Library

2013-11-13

This NASA Hubble Space Telescope set of images reveals a never-before-seen set of six comet-like tails radiating from a body in the asteroid belt, designated P/2013 P5. The asteroid was discovered as an unusually fuzzy-looking object with the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) survey telescope in Hawaii. The multiple tails were discovered in Hubble images taken on Sept. 10, 2013. When Hubble returned to the asteroid on Sept. 23, the asteroid's appearance had totally changed. It looked as if the entire structure had swung around. One interpretation is that the asteroid's rotation rate has been increased to the point where dust is falling off the surface and escaping into space where the pressure of sunlight sweeps out fingerlike tails. According to this theory, the asteroid's spin has been accelerated by the gentle push of sunlight. The object, estimated to be no more than 1,400 feet across, has ejected dust for at least five months, based on analysis of the tail structure. These visible-light, false-color images were taken with Hubble's Wide Field Camera 3. Object Name: P/2013 P5 Image Type: Astronomical/Annotated Credit: NASA, ESA, and D. Jewitt (UCLA) NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

NASA's Hubble Sees Asteroid Spout Six Comet-like Tails

NASA Image and Video Library

2013-11-13

P/2013 P5 on September 23, 2013. --- This NASA Hubble Space Telescope set of images reveals a never-before-seen set of six comet-like tails radiating from a body in the asteroid belt, designated P/2013 P5. The asteroid was discovered as an unusually fuzzy-looking object with the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) survey telescope in Hawaii. The multiple tails were discovered in Hubble images taken on Sept. 10, 2013. When Hubble returned to the asteroid on Sept. 23, the asteroid's appearance had totally changed. It looked as if the entire structure had swung around. One interpretation is that the asteroid's rotation rate has been increased to the point where dust is falling off the surface and escaping into space where the pressure of sunlight sweeps out fingerlike tails. According to this theory, the asteroid's spin has been accelerated by the gentle push of sunlight. The object, estimated to be no more than 1,400 feet across, has ejected dust for at least five months, based on analysis of the tail structure. These visible-light, false-color images were taken with Hubble's Wide Field Camera 3. Object Name: P/2013 P5 Image Type: Astronomical/Annotated Credit: NASA, ESA, and D. Jewitt (UCLA) NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

NASA's Hubble Sees Asteroid Spout Six Comet-like Tails

NASA Image and Video Library

2013-11-13

P/2013 P5 on September 10, 2013. --- This NASA Hubble Space Telescope set of images reveals a never-before-seen set of six comet-like tails radiating from a body in the asteroid belt, designated P/2013 P5. The asteroid was discovered as an unusually fuzzy-looking object with the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) survey telescope in Hawaii. The multiple tails were discovered in Hubble images taken on Sept. 10, 2013. When Hubble returned to the asteroid on Sept. 23, the asteroid's appearance had totally changed. It looked as if the entire structure had swung around. One interpretation is that the asteroid's rotation rate has been increased to the point where dust is falling off the surface and escaping into space where the pressure of sunlight sweeps out fingerlike tails. According to this theory, the asteroid's spin has been accelerated by the gentle push of sunlight. The object, estimated to be no more than 1,400 feet across, has ejected dust for at least five months, based on analysis of the tail structure. These visible-light, false-color images were taken with Hubble's Wide Field Camera 3. Object Name: P/2013 P5 Image Type: Astronomical/Annotated Credit: NASA, ESA, and D. Jewitt (UCLA) NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

SAFARI: Searching Asteroids For Activity Revealing Indicators

NASA Astrophysics Data System (ADS)

Curtis, Anthony; Chandler, Colin Orion; Mommert, Michael; Sheppard, Scott; Trujillo, Chadwick A.

2018-06-01

We present results on one of the deepest and widest systematic searches for active asteroids, objects in the main-belt which behave dynamically like asteroids but display comet-like comae. This activity comes from a variety of sources, such as the sublimation of ices or rotational breakup, the former of which offers an opportunity to study a family of protoplanetary ices different than those seen in comets and Kuiper Belt objects. Indications of activity may be detected through visual or spectroscopic evidence of gas or dust emissions. However, these objects are still poorly understood, with only about 25 identified to date. We looked for activity indicators with a pipeline that examined ~35,000 deep images taken with the Dark Energy Camera (DECam) mounted on the 4-meter Blanco telescope at the Cerro Tololo Inter-American Observatory in Chile. Our pipeline was configured to perform astrometry on DECam images and produce thumbnail images of known asteroids in the field to be examined by eye for signs of activity. We detected three previously identified active asteroids, one of which has shown repeated signs of activity in these data. Our proof of concept demonstrates 1) our novel informatics approach can locate active asteroids 2) DECam data are well suited to search for active asteroids. We will discuss the design structure of our pipeline, adjustments that had to be made for the specific dataset to improve performance, and the the significance of detecting activity in the main-belt. The authors acknowledge funding for this project through NSF grant number AST-1461200.

Targeting an asteroid: The DSPSE encounter with asteroid 1620 Geographos

NASA Technical Reports Server (NTRS)

Yeomans, Donald K.

1993-01-01

Accurate targeting of the Deep Space Program Science Experiment (DSPSE) spacecraft to achieve a 100 km sunward flyby of asteroid 1620 Geographos will require that the ground-based ephemeris of Geographos be well known in advance of the encounter. Efforts are underway to ensure that precision optical and radar observations are available for the final asteroid orbit update that takes place several hours prior to the DSPSE flyby. Because the asteroid passes very close to the Earth six days prior to the DSPSE encounter, precision ground-based optical and radar observations should be available. These ground-based data could reduce the asteroid's position uncertainties (1-sigma) to about 10 km. This ground-based target ephemeris error estimate is far lower than for any previous comet or asteroid that has been under consideration as a mission target.

P/2006 VW139: a main-belt comet born in an asteroid collision?

NASA Astrophysics Data System (ADS)

Novaković, Bojan; Hsieh, Henry H.; Cellino, Alberto

2012-08-01

In this paper, we apply different methods to examine the possibility that a small group of 24 asteroids dynamically linked to a main-belt comet P/2006 VW139, recently discovered by the Pan-STARRS1 survey telescope, shares a common physical origin. By applying the hierarchical clustering and backward integration methods, we find strong evidence that 11 of these asteroids form a sub-group which likely originated in a recent collision event, and that this group includes P/2006 VW139. The objects not found to be part of the 11-member sub-group, which we designate as the P/2006 VW139 family, were either found to be dynamically unstable or are likely interlopers which should be expected due to the close proximity of the Themis family. As we demonstrated, statistical significance of the P/2006 VW139 family is >99 per cent. We determine the age of the family to be 7.5 ± 0.3 Myr, and estimate the diameter of the parent body to be ˜11 km. Results show that the family is produced by an impact which can be best characterized as a transition from the catastrophic to the cratering regime. The dynamical environment of this family is studied as well, including the identification of the most influential mean motion and secular resonances in the region. Our findings now make P/2006 VW139 the second main-belt comet to be dynamically associated with a young asteroid family, a fact with important implications for the origin and activation mechanism of such objects.

Global environmental effects of impact-generated aerosols: Results from a general circulation model

NASA Technical Reports Server (NTRS)

Covey, C.; Ghan, S. J.; Weissman, Paul R.

1988-01-01

Cooling and darkening at Earth's surface are expected to result from the interception of sunlight by the high altitude worldwide dust cloud generated by impact of a large asteroid or comet, according to the one-dimensional radioactive-convective atmospheric model (RCM) of Pollack et al. An analogous three-dimensional general circulation model (GCM) simulation obtains the same basic result as the RCM but there are important differences in detail. In the GCM simulation the heat capacity of the oceans, not included in the RCM, substantially mitigates land surface cooling. On the other hand, the GCM's low heat capacity surface allows surface temperatures to drop much more rapidly than reported by Pollack et al. These two differences between RCM and GCM simulations were noted previously in studies of nuclear winter; GCM results for comet/asteroid winter, however, are much more severe than for nuclear winter because the assumed aerosol amount is large enough to intercept all sunlight falling on Earth. In the simulation the global average of land surface temperature drops to the freezing point in just 4.5 days, one-tenth the time required in the Pollack et al. simulation. In addition to the standard case of Pollack et al., which represents the collision of a 10-km diameter asteroid with Earth, additional scenarios are considered ranging from the statistically more frequent impacts of smaller asteroids to the collision of Halley's comet with Earth. In the latter case the kinetic energy of impact is extremely large due to the head-on collision resulting from Halley's retrograde orbit.

The Hawaii trails project: comet-hunting in the main asteroid belt

NASA Astrophysics Data System (ADS)

Hsieh, H. H.

2009-10-01

Context: The mysterious solar system object 133P/(7968) Elst-Pizarro is dynamically asteroidal, yet displays recurrent comet-like dust emission. Two scenarios were hypothesized to explain this unusual behavior: 1) 133P is a classical comet from the outer solar system that has evolved onto a main-belt orbit or 2) 133P is a dynamically ordinary main-belt asteroid on which subsurface ice has recently been exposed. If 1) is correct, the expected rarity of a dynamical transition onto an asteroidal orbit implies that 133P could be alone in the main belt. In contrast, if 2) is correct, other icy main-belt objects should exist and could also exhibit cometary activity. Aims: Believing 133P to be a dynamically ordinary, yet icy main-belt asteroid, I set out to test the primary prediction of the hypothesis: that 133P-like objects should be common and could be found by an appropriately designed observational survey. Methods: I conducted just such a survey - the Hawaii Trails Project - of selected main-belt asteroids in a search for objects displaying cometary activity. Optical observations were made of targets selected from among the Themis, Koronis, and Veritas asteroid families, the Karin asteroid cluster, and low-inclination, kilometer-scale outer-belt asteroids, using the Lulin 1.0 m, small and moderate aperture research telescope system (SMARTS) 1.0 m, University of Hawaii 2.2 m, southern astrophysical research (SOAR) 4.1 m, Gemini North 8.1 m, Subaru 8.2 m, and Keck I 10 m telescopes. Results: I made 657 observations of 599 asteroids, discovering one active object now known as 176P/LINEAR, leading to the identification of the new cometary class of main-belt comets (MBCs). These results suggest that there could be ~100 currently active MBCs among low-inclination, kilometer-scale outer-belt asteroids. Physically and statistically, MBC activity is consistent with initiation by meter-sized impactors. The estimated rate of impacts and sizes of resulting active sites, however, imply that 133P-sized bodies should become significantly devolatilized over Gyr timescales, suggesting that 133P, and possibly the other MBCs as well, could be secondary, or even multigenerational, fragments from recent breakup events. Some of the data presented herein were obtained at the W. M. Keck Observatory, the Gemini Observatory, Subaru Telescope, National Optical Astronomy Observatory (NOAO) facilities at the Cerro Tololo Inter-American Observatory, and Lulin Observatory. Keck is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration, and was made possible by the generous financial support of the W. M. Keck Foundation. Gemini is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the National Science Foundation (NSF) on behalf of the Gemini partnership. Subaru is operated by the National Astronomical Observatory of Japan. NOAO and Cerro Tololo are operated by the Association of Universities for Research in Astronomy, Inc., under co-operative agreement with the NSF. Lulin is supported and was made possible by the National Science Council of Taiwan, the Ministry of Education of Taiwan, and National Central University. Table [see full textsee full textsee full text] is available in its entirety in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/505/1297 Table 2 is only available in electronic form at http://www.aanda.org

Measurements of Shock Effects Recorded by Hayabusa Samples

NASA Technical Reports Server (NTRS)

Zolensky, Michael; Mikouchi, Takashi; Hagiya, Kenji; Ohsumi, Kazumasa; Martinez, James; Komatsu, Mutsumi; Chan, Queenie H-.S.

2015-01-01

We requested and have been approved for 5 Hayabusa samples in order definitively establish the degree of shock experienced by the regolith of asteroid Itokawa, and to devise a bridge between shock determinations by standard light optical petrography, crystal structures as determined by synchrotron X-ray diffraction (SXRD), and degree of crystallinity as determined by electron back-scattered diffraction (EBSD) [1,2]. As of the writing of this abstract we are awaiting the approved samples. We propose measurements of astromaterial crystal structures and regolith processes. The proposed research work will improve our understanding of how small, primitive solar system bodies formed and evolved, and improve understanding of the processes that determine the history and future of habitability of environments on other solar system bodies. The results of the proposed research will directly enrich the ongoing asteroid and comet exploration missions by NASA, JAXA and ESA, and broaden our understanding of the origin and evolution of small bodies in the early solar system, and elucidate the nature of asteroid and comet regolith.

Measurements of Shock Effects Recorded by Itokawa Samples

NASA Technical Reports Server (NTRS)

Zolensky, Michael; Mikouchi, Takashi; Hagiya, Kenji; Ohsumi, Kazumasa; Martinez, James; Komatsu, Mutsumi; Chan, Queenie H-.S.

2016-01-01

We requested and have been approved for 5 Hayabusa samples in order definitively establish the degree of shock experienced by the regolith of asteroid Itokawa, and to devise a bridge between shock determinations by standard light optical petrography, crystal structures as determined by synchrotron X-ray diffraction (SXRD), and degree of crystallinity as determined by electron back-scattered diffraction (EBSD). As of the writing of this abstract we are awaiting the approved samples. We propose measurements of astromaterial crystal structures and regolith processes. The proposed research work will improve our understanding of how small, primitive solar system bodies formed and evolved, and improve understanding of the processes that determine the history and future of habitability of environments on other solar system bodies. The results of the proposed research will directly enrich the ongoing asteroid and comet exploration missions by NASA, JAXA and ESA, and broaden our understanding of the origin and evolution of small bodies in the early solar system, and elucidate the nature of asteroid and comet regolith.

Top 10 astronomy stories of 2005

NASA Astrophysics Data System (ADS)

Reddy, Francis

2006-01-01

Spacecraft explored two planets and touched a comet, while astronomers puzzled over an errant asteroid, larger galaxies, and a titanic explosion in space. (10) Blast from beyond; (9) Exoplanet surprises; (8) An asteroid among us; (7) Return to space; (6) A year at Saturn ... (5) ... and two at Mars; (4) Deep impact; (3) Bigger, better galaxies; (2) The tenth planet; (1) Huygens lands on Titan.

Using Astrometrica to Teach an Introduction to Asteroid and Comet Astrometry

NASA Astrophysics Data System (ADS)

Durig, Douglas T.

2007-05-01

We have organized a Consortium for Astronomy Research and Teaching (CART) with several small colleges and universities from the Appalachian Colleges Association (ACA). In 2006 we received a small grant from the ACA Teaching and Learning Conference to develop laboratory exercises using the on-line telescopes of the Cordell-Lorenz Observatory of The University of the South in Sewanee, TN. We have completed and tested the first two, Asteroid Astrometry and Comet Astronomy and Angular Size. We are continuing to develop several more on the HR Diagram, Cataclysmic Variables and Short Period Variable Stars. We had unknown new asteroids in the field of view the first four times we performed the Asteroid Astrometry exercise but, unfortunately, none of the students recognized the new objects. However, they were more motivated to perform the exercise because of the opportunity to discover the new objects and they performed better on the review questions than students doing a comparable virtual exercise. Both of the astrometry exercises use the Astrometrica program developed by Herbert Raab and provide an introduction to the use and applications of this very functional shareware program. The program is available for free to educators.

DISINTEGRATING ASTEROID P/2013 R3

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jewitt, David; Li, Jing; Agarwal, Jessica

Splitting of the nuclei of comets into multiple components has been frequently observed but, to date, no main-belt asteroid has been observed to break up. Using the Hubble Space Telescope, we find that main-belt asteroid P/2013 R3 consists of 10 or more distinct components, the largest up to 200 m in radius (assumed geometric albedo of 0.05) each of which produces a coma and comet-like dust tail. A diffuse debris cloud with total mass ∼2 × 10{sup 8} kg further envelopes the entire system. The velocity dispersion among the components, ΔV ∼ 0.2-0.5 m s{sup –1}, is comparable to the gravitational escape speeds ofmore » the largest members, while their extrapolated plane-of-sky motions suggest a break up between 2013 February and September. The broadband optical colors are those of a C-type asteroid. We find no spectral evidence for gaseous emission, placing model-dependent upper limits to the water production rate ≤1 kg s{sup –1}. Breakup may be due to a rotationally induced structural failure of the precursor body.« less

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.

Volatiles in asteroids

NASA Astrophysics Data System (ADS)

Campins, H.

2014-07-01

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

Tidal Forces as Drivers of Collisional Evolution

NASA Technical Reports Server (NTRS)

Asphaug, E.; Agnor, C.; Williams, Q.

2005-01-01

Planetary collisions are usually understood as shock-related phenomena, analogous to impact cratering. But at large scales, where the impact timescale is comparable to the gravitational timescale, collisions can be dominated by gravitational torques and disruptive tides. Shock physics fares poorly, in many respects, in explaining asteroid and meteorite genesis. Melts, melt residues, welded agglomerates and hydrous and gasrich phases among meteorites lead to an array of diverse puzzles whose solution might be explained, in part, by the thermomechanics of tidal unloading. Comet Shoemaker-Levy 9 disrupted in a process that is common in the present and ancestral solar system, so here we consider specific effects tidal disruption had on the evolution of asteroids, comets and meteorites the unaccreted residues of planet formation.

Assessing the physical nature of near-Earth asteroids through their dynamical histories

NASA Astrophysics Data System (ADS)

Fernández, Julio A.; Sosa, Andrea; Gallardo, Tabaré; Gutiérrez, Jorge N.

2014-08-01

We analyze a sample of 139 near-Earth asteroids (NEAs), defined as those that reach perihelion distances q<1.3 au, and that also fulfill the conditions of approaching or crossing Jupiter’s orbit (aphelion distances Q>4.8 au), having Tisserand parameters 24.8 au of cometary origin, but it could be even lower if the NEAs in unstable orbits listed before turn out to be bona fide asteroids from the main belt. This study strengthens the idea that NEAs and comets essentially are two distinct populations, and that periods of dormancy in comets must be rare. Most likely, active comets in near-Earth orbits go through a continuous erosion process in successive perihelion passages until disintegration into meteoritic dust and fragments of different sizes. In this scenario, 289P/Blanpain might be a near-devolatized fragment from a by now disintegrated parent comet.

Spectroscopic Evidence for the Asteroidal Nature of the July 2009 Jovian Impactor

NASA Astrophysics Data System (ADS)

Lisse, Carey; Orton, Glenn; Yanamandra-Fisher, Padma; Fletcher, Leigh; Depater, Imke; Hammel, Heidi

2010-05-01

The collision of a large object with Jupiter on July 19, 2009, heated its atmosphere, modified its composition and generated a prominent field of deposited particulate debris. Low-resolution 7-24 μm spectroscopy of the impact field obtained using the T-ReCS mid-infrared camera/spectrometer on Gemini/South on 24 July 2009 has revealed an excess 9-μm absorption in the impact debris in addition to that supplied by hot ammonia created in the impact. We have searched for candidate materials that would best fit the spectral feature near 9 μm, and find that the feature cannot be matched with candidate materials in Jupiter's atmosphere. A search through a large suite of gaseous and solid absorption spectra (c.f Lisse et al. 2008, 2009) revealed that the major competent matches were for (a) obsidian, a glassy silica, and (b) quartz and cristobalite, crystalline silicas, kinetic alteration products of primitive body ferromagnesian silicates formed at high pressures and temperatures over 1500 K. There are also weak features at 10 - 11 um consistent with olivine absorptions. While the high temperatures required to create silicas are also high enough to destroy the non-refractory water and organics dominating icy cometary bodies, and thus destroy their spectral signal, there was no detectable absorption due to pyroxene materials, which, along with olivines in roughly equal measure, comprise the majority of refractory silicaceous species found in comets (Lisse et al. 2007). This suggests that the impacting body was not a comet, but an olivine-rich differentiated body similar to asteroids that are abundant in the outer regions of the main asteroid belt (Lodders and Fegley 1998). We speculate that the weak structural strength of bulk cometary material causes a comet impactor to catastrophically disrupt at higher altitudes and lower temperatures than a strong, dense asteroidal body, so that the cometary refractory dust component remains relatively cold and unaltered through blowback and Jovian surface deposition, while asteroidal dust is heated enough to be transformed from silicates to silicas. Ancillary evidence for the asteroidal nature of the impactor arises from the singular nature of the impact site, the existence of asteroidal orbits consistent with the observed geometry (Chodas 2009, Orton et al. 2010), and the differences between the observed 2009 opacity spectra of the debris and the observed debris opacity created in July 1994 by the SL9 fragments. Nicholson et al. (1995) noted the presence of a non-gaseous component of their spectrum of the SL9 R fragment impact, which they fit with the 'astronomical silicate' of Draine (1985). Griffith et al. (1997) also required an opacity source besides NH3 gas in order to explain the spectral continuum associated with debris from the L fragment, inferring that it was most likely the result of a silicate feature similar to those in comets (Hanner et al. 1994). Both of these are consistent with increased opacity in the 10-12 μm region due to a mix of stratospheric debris consisting of olivines and pyroxenes, typically found in comets, without any additional opacity at ~9 um due to silica.

Interplanetary spacecraft design using solar electric propulsion

NASA Technical Reports Server (NTRS)

Duxbury, J. H.; Paul, G. M.

1974-01-01

Emphasis of the electric propulsion technology program is now on the application of solar electric propulsion to scientific missions. Candidate planetary, cometary, and geosynchronous missions are being studied. The object of this paper is to describe a basic spacecraft design proposed as the means to accomplish (1) a comet Encke slow flyby, (2) a comet Encke rendezvous, and (3) an out-of-the-ecliptic mission. The discussion includes design differences foreseen for the various missions and indicates those areas where spacecraft design commonality is possible. Particular emphasis is placed on a solar electric propulsion module design which permits an attractive degree of design inheritance from mission to mission.

Near-Earth Asteroid Tracking with the Maui Space Surveillance System (NEAT/MSSS)

NASA Technical Reports Server (NTRS)

Helin, Eleanor F.; Pravdo, Steven H.; Lawrence, Kenneth J.; Hicks, Michael D.

2001-01-01

Over the last year the Jet Propulsion Laboratory's (JPL) Near-Earth Asteroid Tracking (NEAT) program has made significant progress and now consists of two simultaneously-operating, autonomous search systems on the 1.2-m (48") telescopes: on the Maui Space Surveillance System (NEAT/MSSS) and NEAT/Palomar on the Palomar Observatory's Oschin telescope. This paper will focus exclusively on the NEAT/MSSS system. NEAT/MSSS is operated as a partnership between NASA/JPL and the United States Air Force Research Laboratory (AFRL), utilizing the AFRL 1.2-m telescope on the 3000-m summit of Haleakala, Maui, The USAF Space Command (SPCMD) contributed financial support to build and install the 'NEAT focal reducer' on the MSSS 1.2-m telescope giving it a large field of view (2.5 square degrees), suitable for the near-earth object (NEO),both asteroids and comets, survey. This work was completed in February 2000. AFRL has made a commitment to NEAT/MSSS that allows NEAT to operate full time with the understanding that AFRL participate as partners in NEAT/MSSS and have use of the NEAT camera system for high priority satellite observations during bright time (parts of 12 nights each month). Currently, NEAT has discovered 42 NEAs including 12 larger than 1-km, 5 Potentially Hazardous Asteroids (PHAs), 6 comets, and nearly 25,000 asteroid detections since March 2000.

A late Miocene dust shower from the break-up of an asteroid in the main belt.

PubMed

Farley, Kenneth A; Vokrouhlický, David; Bottke, William F; Nesvorný, David

2006-01-19

Throughout the history of the Solar System, Earth has been bombarded by interplanetary dust particles (IDPs), which are asteroid and comet fragments of diameter approximately 1-1,000 microm. The IDP flux is believed to be in quasi-steady state: particles created by episodic main belt collisions or cometary fragmentation replace those removed by comminution, dynamical ejection, and planetary or solar impact. Because IDPs are rich in 3He, seafloor sediment 3He concentrations provide a unique means of probing the major events that have affected the IDP flux and its source bodies over geological timescales. Here we report that collisional disruption of the >150-km-diameter asteroid that created the Veritas family 8.3 +/- 0.5 Myr ago also produced a transient increase in the flux of interplanetary dust-derived 3He. The increase began at 8.2 +/- 0.1 Myr ago, reached a maximum of approximately 4 times pre-event levels, and dissipated over approximately 1.5 Myr. The terrestrial IDP accretion rate was overwhelmingly dominated by Veritas family fragments during the late Miocene. No other event of this magnitude over the past approximately 10(8) yr has been deduced from main belt asteroid orbits. One remarkably similar event is present in the 3He record 35 Myr ago, but its origin by comet shower or asteroid collision remains uncertain.

Detection of solid C(triple bond)N bearing materials on solar system bodies

NASA Technical Reports Server (NTRS)

Cruikshank, Dale P.; Hartmann, W. K.; Tholen, David J.; Allamandola, L. J.; Brown, R. H.; Matthews, C. N.; Bell, J. F.

1991-01-01

We found observational evidence for the presence of C(triple bond)N-bearing solid materials on four classes of Solar System bodies: comets, asteroids, the rings of Uranus, and Saturn's satellite Iapetus. Gaseous CN was known in comet spectra, and the IR spectra of Comet P/Halley show emission of the CN fundamental at 4.5 microns interpreted as solids containing CN- group in the grains of the inner coma. The presented data offer the first evidence for chemically related material on the other objects.

Dust bands in the asteroid belt

NASA Technical Reports Server (NTRS)

Sykes, Mark V.; Greenberg, Richard; Dermott, Stanley F.; Nicholson, Philip D.; Burns, Joseph A.

1989-01-01

This paper describes the original IRAS observations leading to the discovery of the three dust bands in the asteroid belt and the analysis of data. Special attention is given to an analytical model of the dust band torus and to theories concerning the origin of the dust bands, with special attention given to the collisional equilibrium (asteroid family), the nonequilibrium (random collision), and the comet hypotheses of dust-band origin. It is noted that neither the equilibrium nor nonequilibrium models, as currently formulated, present a complete picture of the IRAS dust-band observations.

Search for Dormant Comets in Near-Earth Space

NASA Astrophysics Data System (ADS)

Kim, Yoonyoung

2013-06-01

It is considered that comets have been injected into near-Earth space from outer region (e.g. Kuiper-belt region), providing rich volatile and organic compounds to the earth. Some comets are still active while most of them are dormant with no detectable tails and comae. Here we propose to make a multi-band photometric observation of near-Earth objects (NEOs) with comet-like orbits. We select our targets out of infrared asteroidal catalogs based on AKARI and WISE observations. With a combination of taxonomic types by Subaru observation and albedos by AKARI or WISE, we aim to dig out dormant comet candidates among NEOs. Our results will provide valuable information to figure out the dynamical evolution and fate of comets. We would like to emphasize that this is the first taxonomic survey of dormant comets to utilize the infrared data archive with AKARI and WISE.

Electric solar-wind sail for asteroid touring missions and planetary protection

NASA Astrophysics Data System (ADS)

Janhunen, P.

2014-07-01

The electric solar-wind sail (electric sail, E-sail [1,2]) is a relatively new concept for moving around in the solar system without consuming propellant and by using the thrust provided by the natural solar wind to produce propulsion. The E-sail is based on deploying, using the centrifugal force, a set of long, thin metallic tethers and charging them to high positive voltage by actively removing negative charge from the system by an electron gun. To make the tethers resistant towards inevitable wire cuts by micrometeoroids, they must be made by bonding from multiple (typically 4) thin (25--50 μ m) aluminium wires. Production of the tethers was a technical challenge which was recently overcome. According to present numerical estimates, the E-sail could produce up to 1 N of propellantless thrust out of less than 200 kg package which is enough to give characteristic acceleration of 1 mm/s^2 to a spacecraft weighing 1 tonne, thus producing 30 km/s of delta-v per year. The thrust scales as ˜ 1/r where r is the solar distance. There are ways to control and vector the thrust enough to enable inward and outward spiralling missions in the solar system. The E-sail working principle has been indirectly measured in a laboratory, and ESTCube-1 CubeSat experiment is underway in orbit (in late March 2014 it was waiting to be started) to measure the E-sail thrust acting on a short 10-m long tether. A full-scale mission requires ˜ 1000 km of tether altogether (weighing ˜10 kg). The production of a 1-km piece of tether has been demonstrated in laboratory [3]. If the E-sail holds up its present promise, it would be ideally suited for asteroid missions because it enables production of similar level of thrust than ion engines, but needs only a small fraction of the electric power and never runs out of propellant because it does not use any (the ''propellant'' being the natural solar-wind plasma flow). Here we consider especially a mission which would tour the asteroid belt for a long time, moving from asteroid to asteroid in a bit similar way as, e.g., Mars rovers move from rock to rock on the planet's surface. After starting from the Earth, the mission would slowly spiral outward, making rendezvous with interesting asteroids along the way, as well as flybys or even a larger number of asteroids as opportunities arise. The spacecraft would do remote sensing of the bodies and perhaps also deploy small CubeSat-sized expendable landers on them (the mother spacecraft cannot land on an asteroid or else it would lose the E-sail tethers). The mission would first explore near-Earth objects, then pass through the main belt and end up with the Trojans, exploring asteroids in rendezvous and flyby modes all the time. Asteroids in roughly circular orbits and at low inclination would be the easiest and most likely targets for rendezvous mode encounters, while there would be less restrictions for flyby mode observations. Besides for pure asteroid science, the E-sail could also be used for planetary protection, either through direct propulsive deflection of a dangerous asteroid [4] or by accelerating a relatively lightweight impactor spacecraft to a retrograde orbit and in that way maximizing the available deflecting impact energy for given impactor mass. E-sails could take a number of such impactors to retrograde storage orbits from which they could be commanded to impact a dangerous asteroid with relatively short warning time. Such impactor fleet would not be dangerous to the Earth because the vehicles can be designed to burn completely in the atmosphere, in the unlikely event that due to some mishap one of them would collide with the Earth. The E-sail has potentially large applicability to asteroids as it promises ''free'' transportation in the solar system. As a next step, a solar-wind test mission is needed to demonstrate the technology in the authentic environment.

Near Earth asteroids associated with the Sigma-Capricornids meteoroid stream

NASA Astrophysics Data System (ADS)

Gulchekhra, Kokhirova; Pulat, Babadzhanov; Umed, Khamroev

The Near Earth Asteroids (NEAs) 2008BO16, 2011EC41, and 2013CT36 (http://newton.dm.\\unipi.it/neodys, 2013) have very similar orbits according to the D_{SH} criterion of Southworth, Hawkins (1963). Additionally, their orbits are classed as comet-like by the Tisserand invariant values (Kresak 1982; Kosai 1992). The orbital evolution investigation shows, that during one cycle of variations of the argument of perihelion omega, the asteroids cross the Earth’s orbit four times. Consequently, a developed meteoroid stream, possible associated with them, might produce four meteor showers (Babadzhanov, Obrubov 1992). Theoretical parameters of the predicted showers were calculated and identified with the observable nighttime sigma-Capricornids (Sekanina 1973; Jenniskens 2006) and chi-Sagittarids (Sekanina 1976), and daytime chi-Capricornids (Sekanina 1976) and Capricornids-Sagittarids (Sekanina 1973) meteor showers. The similar and comet-like orbits and association with the meteoroid stream producing four active showers are strong indications that these asteroids have a common cometary origin. Earlier the NEAs (2101) Adonis and 1995CS, which additionally is potentially hazardous asteroid (PHA), were recognized as dormant comets because of their link with the same meteoroid stream (Babadzhanov 2003). So, a conclusion was made, that either the considered NEAs are large sized splinters of the Adonis, or all five objects are fragments of a larger comet that was the parent body of the sigma-Capricornids meteoroid stream, and whose break-up occurred several tens of thousands years ago. During 2010-2011 years three fireballs were photographed by the Tajikistan fireball network (Babadzhanov, Kokhirova 2009), belonging to the sigma-Capricornids meteor shower. Taking into account the observations else six fireballs of this shower in the Canada and USA (Halliday et al. 1996; McCrosky et al. 1978), the mean radiant coordinates, the period of activity, as well as the mean daily radiant drift of the sigma-Capricornids were determined. Further to the PE criterion (Ceplecha, McCrosky 1976), the values of bulk density of the nine fireball producing meteoroids are in the range 0.2-3.5 g cm(-3) that suggests a non-homogeneous compound of the comet-progenitor of the sigma-Capricornids fireball shower. size{ References Babadzhanov, P.B., 2003, A&A,397, 319 Babadzhanov, P.B., Kokhirova, G.I., 2009, Izv. Ak. Nauk Resp. Taj.,2(135),46 Babadzhanov, P.B., Obrubov, Yu.V., 1992, Cel. Mech.& Dyn. Astron., v.54, p.111 Ceplecha, Z., McCrosky, R.E.J., 1976, J. Geophys. Res., 81, 6257 Halliday, I., Griffin, A.A., Blackwell, A.T., 1996, Met.& Planet. Sci., 31, 185 Jenniskens, P., 2006, Meteor showers and their parent comets, New- York: Cambridge Univ. Press, p. 790 Kosai, H., 1992, Cel. Mech. & Dyn. Astron., 54, 237 Kresak, L., 1982, BAC, 33, 104 McCrosky, R.E., Shao, C.Y., Posen, A., 1978, Meteoritika, 37, 44 Sekanina Z., 1973, Icarus, 18, 253 Sekanina Z., 1976, Icarus, 27, 265 Southworth, R.B., Hawkins, G.S., 1963, Smith. Cont. Aph. 7, 261}

Orbit Refinement of Asteroids and Comets Using a Robotic Telescope Network

NASA Astrophysics Data System (ADS)

Lantz Caughey, Austin; Brown, Johnny; Puckett, Andrew W.; Hoette, Vivian L.; Johnson, Michael; McCarty, Cameron B.; Whitmore, Kevin; UNC-Chapel Hill SKYNET Team

2016-01-01

We report on a multi-semester project to refine the orbits of asteroids and comets in our Solar System. One of the newest fields of research for undergraduate Astrophysics students at Columbus State University is that of asteroid astrometry. By measuring the positions of an asteroid in a set of images, we can reduce the overall uncertainty in the accepted orbital parameters of that object. These measurements, using our WestRock Observatory (WRO) and several other telescopes around the world, are being published through the Minor Planet Center (MPC) and benefit the global community.Three different methods are used to obtain these observations. First, we use our own 24-inch telescope at WRO, located in at CSU's Coca-Cola Space Science Center in downtown Columbus, Georgia . Second, we have access to data from the 20-inch telescope at Stone Edge Observatory in El Verano, California. Finally, we may request images remotely using Skynet, an online worldwide network of robotic telescopes. Our primary and long-time collaborator on Skynet has been the "41-inch" reflecting telescope at Yerkes Observatory in Williams Bay, Wisconsin. Thus far, we have used these various telescopes to refine the orbits of more than 15 asteroids and comets. We have also confirmed the resulting reduction in orbit-model uncertainties using Monte Carlo simulations and orbit visualizations, using Find_Orb and OrbitMaster software, respectively.Before any observatory site can be used for official orbit refinement projects, it must first become a trusted source of astrometry data for the MPC. We have therefore obtained Observatory Codes not only for our own WestRock Observatory (W22), but also for 3 Skynet telescopes that we may use in the future: Dark Sky Observatory in Boone, North Carolina (W38) Hume Observatory in Santa Rosa, California (U54) and Athabasca University Geophysical Observatory in Athabasca, Alberta, Canada (U96).

Deflection and fragmentation of near-earth asteroids

NASA Technical Reports Server (NTRS)

Ahrens, Thomas J.; Harris, Alan W.

1992-01-01

The collision with earth of near-earth asteroids or comet nuclei poses a potential threat to mankind. Objects about 100 m in diameter could be diverted from an earth-crossing trajectory by the impact of a rocket-launched mass, but for larger bodies nuclear explosions seem to be the only practical means of deflection. Fragmentation of the body by nuclear charges is less efficient or secure.

Dynamics of Populations of Planetary Systems (IAU C197)

NASA Astrophysics Data System (ADS)

Knezevic, Zoran; Milani, Andrea

2005-05-01

1. Resonances and stability of extra-solar planetary systems C. Beaugé, N. Callegari, S. Ferraz-Mello and T. A. Michtchenko; 2. Formation, migration, and stability of extrasolar planetary systems Fred C. Adams; 3. Dynamical evolution of extrasolar planetary systems Ji-Lin Zhou and Yi-Sui Sun; 4. Dynamics of planetesimals: the role of two-body relaxation Eiichiro Kokubo; 5. Fitting orbits Andrzej J. Maciejewski, Krzysztof Gozdziewski and Szymon Kozlowski; 6. The secular planetary three body problem revisited Jacques Henrard and Anne-Sophie Libert; 7. Dynamics of extrasolar systems at the 5/2 resonance: application to 47 UMa Dionyssia Psychoyos and John D. Hadjidemetriou; 8. Our solar system as model for exosolar planetary systems Rudolf Dvorak, Áron Süli and Florian Freistetter; 9. Planetary motion in double stars: the influence of the secondary Elke Pilat-Lohinger; 10. Planetary orbits in double stars: influence of the binary's orbital eccentricity Daniel Benest and Robert Gonczi; 11. Astrometric observations of 51 Peg and Gliese 623 at Pulkovo observatory with 65 cm refractor N. A. Shakht; 12. Observations of 61 Cyg at Pulkovo Denis L. Gorshanov, N. A. Shakht, A. A. Kisselev and E. V. Poliakow; 13. Formation of the solar system by instability Evgeny Griv and Michael Gedalin; 14. Behaviour of a two-planetary system on a cosmogonic time-scale Konstantin V. Kholshevnikov and Eduard D. Kuznetsov; 15. Boundaries of the habitable zone: unifying dynamics, astrophysics, and astrobiology Milan M. Cirkovic; 16. Asteroid proper elements: recent computational progress Fernando Roig and Cristian Beaugé; 17. Asteroid family classification from very large catalogues Anne Lemaitre; 18. Non-gravitational perturbations and evolution of the asteroid main belt David Vokrouhlicky, M. Broz and W. F. Bottke, D. Nesvorny and A. Morbidelli; 19. Diffusion in the asteroid belt Harry Varvoglis; 20. Accurate model for the Yarkovsky effect David Capek and David Vokrouhlicky; 21. The population of asteroids in the 2:1 mean motion resonance with Jupiter revised Miroslav Broz, D. Vokrouhlicky, F. Roig, D. Nesvorny, W. F. Bottke and A. Morbidelli; 22. On the reliability of computation of maximum Lyapunov Characteristic Exponents for asteroids Zoran Knezevic and Slobodan Ninkovic; 23. Nekhoroshev stability estimates for different models of the Trojan asteroids Christos Efthymiopoulos; 24. The role of the resonant 'stickiness' in the dynamical evolution of Jupiter family comets A. Alvarez-Canda and F. Roig; 25. Regimes of stability and scaling relations for the removal time in the asteroid belt: a simple kinetic model and numerical tests Mihailo Cubrovic; 26. Virtual asteroids and virtual impactors Andrea Milani; 27. Asteroid population models Alessandro Morbidelli; 28. Linking Very Large Telescope asteroid observations M. Granvik, K. Muinonen, J. Virtanen, M. Delbó, L. Saba, G. De Sanctis, R. Morbidelli, A. Cellino and E. Tedesco; 29. Collision orbits and phase transition for 2004 AS1 at discovery Jenni Virtanen, K. Muinonen, M. Granvik and T. Laakso; 30. The size of collision solutions in orbital elements space G. B. Valsecchi, A. Rossi, A. Milani and S. R. Chesley; 31. Very short arc orbit determination: the case of asteroid 2004 FU162 Steven R. Chesley; 32. Nonlinear impact monitoring: 2-dimensional sampling Giacomo Tommei; 33. Searching for gravity assisted trajectories to accessible near-Earth asteroids Stefan Berinde; 34. KLENOT - Near Earth and other unusual objects observations Michal Kocer, Jana Tichá and M. Tichy; 35. Transport of comets to the Inner Solar System Hans Rickman; 36. Nongravitational Accelerations on Comets Steven R. Chesley and Donald K. Yeomans; 37. Interaction of planetesimals with the giant planets and the shaping of the trans-Neptunian belt Harold F. Levison and Alessandro Morbidelli; 38. Transport of comets to the outer p

Water in primitive solar system bodies

NASA Astrophysics Data System (ADS)

Yang, Bin

This is a dissertation on the physical properties, particularly, the water distribution in three small body populations of the solar system: (1) the Jovian Trojans, (2) the main-belt B-type asteroids and (3) the comets. Using near-infrared (NIR) spectroscopy, I have sought diagnostic (especially water) features in the Trojans. My sample is focused on objects identified in previous measurements as being of special interest. I found that the high albedo Trojan (4709) Ennomos has a featureless spectrum and that its surface contains no more than 10% water ice. In addition, the organic-like features reported earlier for Trojans (617) Patroclus, (911) Agamemnon, (1143) Odysseus and (2797) Teucer were not confirmed. Furthermore, my observations of seven Trojan asteroids that have been formerly reported to show silicate-like absorption features did not confirm the features in their spectra. My broadband photometric observations of two Trojan families (the Eurybates and the 1986WD family) showed that five Eurybates Trojans and one 1986WD Trojan exhibit UV drop-offs, indicating the presence of hydrated minerals on these objects. B-type asteroids are rare, blue asteroids, of which 2 Pallas is the largest and most famous example. In a focused, spectroscopic study of 20 B-type asteroids, I found that optically similar B-type asteroids are spectrally diverse in the near infrared. The negative optical spectral slope is due to the presence of a broad absorption band centered near 1.0 mm, which can often be modeled using magnetite. The best meteorite analogs for B-types are the unusual CI and CM carbonaceous chondrites. In the NIR spectra of the outburst comet 17P/Holmes, I found two broad absorption bands with centers (at 2mm and 3mm, respectively) and overall shapes consistent with the presence of micron-sized water ice grains in the coma. These features together with the discovery of excess 3mm thermal emission, suggests that the coma of 17P/Holmes has two components (hot, refractory dust and cold ice grains) which are not in thermal contact. I also detected the 1.5- and 2-mm water ice absorption features in the two bright Oort cloud comets, C/ 2005L3 and C/2006W3.

Generation of NEP heliocentric trajectory data

NASA Technical Reports Server (NTRS)

Horsewood, J. L.; Brice, K. B.

1972-01-01

A study, designed to generate representative nuclear electric propulsion data for rendezvous missions to the comet Encke using the variational calculus program HILTOP, is presented. Other purposes of the study include a comparison of the HILTOP data with equivalent data generated with QUICKTOP program and to propose approaches for storing and subsequently accessing the optimum trajectory and performance data in the QUICKLY program.

Geomorphological Mapping on the Southern Hemisphere of Comet 67P/Churyumov-Gerasimenko

NASA Astrophysics Data System (ADS)

Lee, Jui-Chi; Massironi, Matteo; Giacomini, Lorenza; Ip, Wing-Huen; El-Maarry, Mohamed R.

2016-04-01

Since its rendezvous with comet 67P/Churyumov-Gerasimenko on the sixth of August, 2014, the Rosetta spacecraft has carried out close-up observations of the nucleus and coma of this Jupiter family comet. The OSIRIS, the Scientific Imaging Camera System onboard the Rosetta spacecraft, which consists of a narrow-angle and wide-angle camera (NAC and WAC), has made detailed investigations of the physical properties and surface morphology of the comet. From May 2015, the southern hemisphere of the comet became visible and the adaptical resolution was high enough for us to do a detailed analysis of the surface. Previous work shows that the fine particle deposits are the most extensive geomorphological unit in the northern hemisphere. On the contrary, southern hemisphere is dominated by rocky-like stratified terrain. The southern hemisphere of the nucleus surface reveals quite different morphologies from the northern hemisphere. This could be linked to the different insolation condition between northern and southern hemisphere. As a result, surface geological processes could operate with a diverse intensity on the different sides of the comet nucleus. In this work, we provide the geomorphological maps of the southern hemisphere with linear features and geological units identified. The geomorphological maps described in this study allow us to understand the processes and the origin of the comet.

Global environmental effects of impact-generated aerosols: Results from a general circulation model, revision 1

NASA Technical Reports Server (NTRS)

Covey, Curt; Ghan, Steven J.; Walton, John J.; Weissman, Paul R.

1989-01-01

Interception of sunlight by the high altitude worldwide dust cloud generated by impact of a large asteroid or comet would lead to substantial land surface cooling, according to our three-dimensional atmospheric general circulation model (GCM). This result is qualitatively similar to conclusions drawn from an earlier study that employed a one-dimensional atmospheric model, but in the GCM simulation the heat capacity of the oceans substantially mitigates land surface cooling, an effect that one-dimensional models cannot quantify. On the other hand, the low heat capacity of the GCM's land surface allows temperatures to drop more rapidly in the initial stage of cooling than in the one-dimensional model study. These two differences between three-dimensional and one-dimensional model simulations were noted previously in studies of nuclear winter; GCM-simulated climatic changes in the Alvarez-inspired scenario of asteroid/comet winter, however, are more severe than in nuclear winter because the assumed aerosol amount is large enough to intercept all sunlight falling on earth. Impacts of smaller objects could also lead to dramatic, though less severe, climatic changes, according to our GCM. Our conclusion is that it is difficult to imagine an asteroid or comet impact leading to anything approaching complete global freezing, but quite reasonable to assume that impacts at the Alvarez level, or even smaller, dramatically alter the climate in at least a patchy sense.

A mathematical model of the passage of an asteroid-comet body through the Earth’s atmosphere

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shaydurov, V., E-mail: shaidurov04@mail.ru; Siberian Federal University, 79 Svobodny pr., 660041 Krasnoyarsk; Shchepanovskaya, G.

In the paper, a mathematical model and a numerical algorithm are proposed for modeling the complex of phenomena which accompany the passage of a friable asteroid-comet body through the Earth’s atmosphere: the material ablation, the dissociation of molecules, and the radiation. The proposed model is constructed on the basis of the Navier-Stokes equations for viscous heat-conducting gas with an additional equation for the motion and propagation of a friable lumpy-dust material in air. The energy equation is modified for the relation between two its kinds: the usual energy of the translation of molecules (which defines the temperature and pressure) andmore » the combined energy of their rotation, oscillation, electronic excitation, dissociation, and radiation. For the mathematical model of atmosphere, the distribution of density, pressure, and temperature in height is taken as for the standard atmosphere. An asteroid-comet body is taken initially as a round body consisting of a friable lumpy-dust material with corresponding density and significant viscosity which far exceed those for the atmosphere gas. A numerical algorithm is proposed for solving the initial-boundary problem for the extended system of Navier-Stokes equations. The algorithm is the combination of the semi-Lagrangian approximation for Lagrange transport derivatives and the conforming finite element method for other terms. The implementation of these approaches is illustrated by a numerical example.« less

Optimal design of near-Earth asteroid sample-return trajectories in the Sun-Earth-Moon system

NASA Astrophysics Data System (ADS)

He, Shengmao; Zhu, Zhengfan; Peng, Chao; Ma, Jian; Zhu, Xiaolong; Gao, Yang

2016-08-01

In the 6th edition of the Chinese Space Trajectory Design Competition held in 2014, a near-Earth asteroid sample-return trajectory design problem was released, in which the motion of the spacecraft is modeled in multi-body dynamics, considering the gravitational forces of the Sun, Earth, and Moon. It is proposed that an electric-propulsion spacecraft initially parking in a circular 200-km-altitude low Earth orbit is expected to rendezvous with an asteroid and carry as much sample as possible back to the Earth in a 10-year time frame. The team from the Technology and Engineering Center for Space Utilization, Chinese Academy of Sciences has reported a solution with an asteroid sample mass of 328 tons, which is ranked first in the competition. In this article, we will present our design and optimization methods, primarily including overall analysis, target selection, escape from and capture by the Earth-Moon system, and optimization of impulsive and low-thrust trajectories that are modeled in multi-body dynamics. The orbital resonance concept and lunar gravity assists are considered key techniques employed for trajectory design. The reported solution, preliminarily revealing the feasibility of returning a hundreds-of-tons asteroid or asteroid sample, envisions future space missions relating to near-Earth asteroid exploration.

Spacecraft Conceptual Design for Returning Entire Near-Earth Asteroids

NASA Technical Reports Server (NTRS)

Brophy, John R.; Oleson, Steve

2012-01-01

In situ resource utilization (ISRU) in general, and asteroid mining in particular are ideas that have been around for a long time, and for good reason. It is clear that ultimately human exploration beyond low-Earth orbit will have to utilize the material resources available in space. Historically, the lack of sufficiently capable in-space transportation has been one of the key impediments to the harvesting of near-Earth asteroid resources. With the advent of high-power (or order 40 kW) solar electric propulsion systems, that impediment is being removed. High-power solar electric propulsion (SEP) would be enabling for the exploitation of asteroid resources. The design of a 40-kW end-of-life SEP system is presented that could rendezvous with, capture, and subsequently transport a 1,000-metric-ton near-Earth asteroid back to cislunar space. The conceptual spacecraft design was developed by the Collaborative Modeling for Parametric Assessment of Space Systems (COMPASS) team at the Glenn Research Center in collaboration with the Keck Institute for Space Studies (KISS) team assembled to investigate the feasibility of an asteroid retrieval mission. Returning such an object to cislunar space would enable astronaut crews to inspect, sample, dissect, and ultimately determine how to extract the desired materials from the asteroid. This process could jump-start the entire ISRU industry.

Advanced Curation of Current and Future Extraterrestrial Samples

NASA Technical Reports Server (NTRS)

Allen, Carlton C.

2013-01-01

Curation of extraterrestrial samples is the critical interface between sample return missions and the international research community. Curation includes documentation, preservation, preparation, and distribution of samples. The current collections of extraterrestrial samples include: Lunar rocks / soils collected by the Apollo astronauts Meteorites, including samples of asteroids, the Moon, and Mars "Cosmic dust" (asteroid and comet particles) collected by high-altitude aircraft Solar wind atoms collected by the Genesis spacecraft Comet particles collected by the Stardust spacecraft Interstellar dust collected by the Stardust spacecraft Asteroid particles collected by the Hayabusa spacecraft These samples were formed in environments strikingly different from that on Earth. Terrestrial contamination can destroy much of the scientific significance of many extraterrestrial materials. In order to preserve the research value of these precious samples, contamination must be minimized, understood, and documented. In addition the samples must be preserved - as far as possible - from physical and chemical alteration. In 2011 NASA selected the OSIRIS-REx mission, designed to return samples from the primitive asteroid 1999 RQ36 (Bennu). JAXA will sample C-class asteroid 1999 JU3 with the Hayabusa-2 mission. ESA is considering the near-Earth asteroid sample return mission Marco Polo-R. The Decadal Survey listed the first lander in a Mars sample return campaign as its highest priority flagship-class mission, with sample return from the South Pole-Aitken basin and the surface of a comet among additional top priorities. The latest NASA budget proposal includes a mission to capture a 5-10 m asteroid and return it to the vicinity of the Moon as a target for future sampling. Samples, tools, containers, and contamination witness materials from any of these missions carry unique requirements for acquisition and curation. Some of these requirements represent significant advances over methods currently used. New analytical and screening techniques will increase the value of current sample collections. Improved web-based tools will make information on all samples more accessible to researchers and the public. Advanced curation of current and future extraterrestrial samples includes: Contamination Control - inorganic / organic Temperature of preservation - subfreezing / cryogenic Non-destructive preliminary examination - X-ray tomography / XRF mapping / Raman mapping Microscopic samples - handling / sectioning / transport Special samples - unopened lunar cores Informatics - online catalogs / community-based characterization.

NASA's Asteroid Redirect Mission: Overview and Status

NASA Astrophysics Data System (ADS)

Abell, Paul; Gates, Michele; Johnson, Lindley; Chodas, Paul; Brophy, John; Mazanek, Dan; Muirhead, Brian

A major element of the National Aeronautics and Space Administration’s (NASA) new Asteroid Initiative is the Asteroid Redirect Mission (ARM). This concept was first proposed in 2011 during a feasibility study at the Keck Institute for Space Studies (KISS)[1] and is under consideration for implementation by NASA. The ARM involves sending a high-efficiency (ISP 3000 s), high-power (40 kW) solar electric propulsion (SEP) robotic vehicle that leverages technology developed by NASA’s Space Technology Mission Directorate (STMD) to rendezvous with a near-Earth asteroid (NEA) and return asteroidal material to a stable lunar distant retrograde orbit (LDRO)[2]. There are two mission concepts currently under study, one that captures an entire 7 - 10 meter mean diameter NEA[3], and another that retrieves a 1 - 10 meter mean diameter boulder from a 100+ meter class NEA[4]. Once the retrieved asteroidal material is placed into the LDRO, a two person crew would launch aboard an Orion capsule to rendezvous and dock with the robotic SEP vehicle. After docking, the crew would conduct two extra-vehicular activities (EVA) to collect asteroid samples and deploy instruments prior to Earth return. The crewed portion of the mission is expected to last approximately 25 days and would represent the first human exploration mission beyond low-Earth orbit (LEO) since the Apollo program. The ARM concept leverages NASA’s activities in Human Exploration, Space Technology, and Planetary Defense to accomplish three primary objectives and several secondary objectives. The primary objective relevant to Human Exploration is to gain operational experience with vehicles, systems, and components that will be utilized for future deep space exploration. In regard to Space Technology, the ARM utilizes advanced SEP technology that has high power and long duration capabilities that enable future missions to deep space destinations, such as the Martian system. With respect to Planetary Defense, the ARM mission will utilize an enhanced NEA observation campaign that will detect, track, and characterize both spacecraft mission targets and potentially hazardous asteroids that may threaten Earth in the future. Potential secondary objectives for ARM include planetary defense demonstrations at the NEA, conducting planetary science (both during the robotic and crewed mission segments), and encouraging commercial and international partnership opportunities. References [1] J. Brophy et al., “Asteroid Retrieval Feasibility Study,” Keck Institute for Space Studies Report, April 2012. [2] N. Strange et al., “Overview of Mission Design for NASA Asteroid Redirect Robotic Mission Concept,” presented at the 33rd International Electric Propulsion Conference, The George Washington University, Washington, D.C., October 2013. [3] B. Muirhead, J. Brophy “Asteroid Redirect Robotic Mission Feasibility Study,” presented at IEEE Aerospace Conference, Big Sky, Montana, March 2014. [4] Mazenek et al., “Asteroid Redirect Robotic Mission: Alternate Concept Overview”, American Institute of Aeronautics and Astronautics, Space 2014 Conference, San Diego, California, August 2014.

Main-belt comets in the Palomar Transient Factory survey - I. The search for extendedness

NASA Astrophysics Data System (ADS)

Waszczak, A.; Ofek, E. O.; Aharonson, O.; Kulkarni, S. R.; Polishook, D.; Bauer, J. M.; Levitan, D.; Sesar, B.; Laher, R.; Surace, J.; PTF Team

2013-08-01

Cometary activity in main-belt asteroids probes the ice content of these objects and provides clues to the history of volatiles in the inner Solar system. We search the Palomar Transient Factory survey to derive upper limits on the population size of active main-belt comets (MBCs). From data collected from 2009 March through 2012 July, we extracted ˜2 million observations of ˜220 thousand known main-belt objects (40 per cent of the known population, down to ˜1-km diameter) and discovered 626 new objects in multinight linked detections. We formally quantify the `extendedness' of a small-body observation, account for systematic variation in this metric (e.g. due to on-sky motion) and evaluate this method's robustness in identifying cometary activity using observations of 115 comets, including two known candidate MBCs and six newly discovered non-MBCs (two of which were originally designated as asteroids by other surveys). We demonstrate a 66 per cent detection efficiency with respect to the extendedness distribution of the 115 sampled comets, and a 100 per cent detection efficiency with respect to extendedness levels greater than or equal to those we observed in the known candidate MBCs P/2010 R2 (La Sagra) and P/2006 VW139. Using a log-constant prior, we infer 95 per cent confidence upper limits of 33 and 22 active MBCs (per million main-belt asteroids down to ˜1-km diameter), for detection efficiencies of 66 and 100 per cent, respectively. In a follow-up to this morphological search, we will perform a photometric (disc-integrated brightening) search for MBCs.

Rendezvous missions with minimoons from L1

NASA Astrophysics Data System (ADS)

Chyba, M.; Haberkorn, T.; Patterson, G.

2014-07-01

We propose to present asteroid capture missions with the so-called minimoons. Minimoons are small asteroids that are temporarily captured objects on orbits in the Earth-Moon system. It has been suggested that, despite their small capture probability, at any time there are one or two meter diameter minimoons, and progressively greater numbers at smaller diameters. The minimoons orbits differ significantly from elliptical orbits which renders a rendezvous mission more challenging, however they offer many advantages for such missions that overcome this fact. First, they are already on geocentric orbits which results in short duration missions with low Delta-v, this translates in cost efficiency and low-risk targets. Second, beside their close proximity to Earth, an advantage is their small size since it provides us with the luxury to retrieve the entire asteroid and not only a sample of material. Accessing the interior structure of a near-Earth satellite in its morphological context is crucial to an in-depth analysis of the structure of the asteroid. Historically, 2006 RH120 is the only minimoon that has been detected but work is ongoing to determine which modifications to current observation facilities is necessary to provide detection algorithm capabilities. In the event that detection is successful, an efficient algorithm to produce a space mission to rendezvous with the detected minimoon is highly desirable to take advantage of this opportunity. This is the main focus of our work. For the design of the mission we propose the following. The spacecraft is first placed in hibernation on a Lissajoux orbit around the liberation point L1 of the Earth-Moon system. We focus on eight-shaped Lissajoux orbits to take advantage of the stability properties of their invariant manifolds for our transfers since the cost to minimize is the spacecraft fuel consumption. Once a minimoon has been detected we must choose a point on its orbit to rendezvous (in position and velocities) with the spacecraft. This is determined using a combination of distance between the minimoon's orbit to L1 and its energy level with respect to the Lissajoux orbit on which the spacecraft is hibernating. Once the spacecraft rendezvous with the minimoon, it will escort the temporarily captured object to analyze it until the withdrawal time when the spacecraft exits the orbit to return to its hibernating location awaiting for another minimoon to be detected. The entire mission including the return portion can be stated as an optimal control problem, however we choose to break it into smaller sub-problems as a first step to be refined later. To model our control system, we use the circular three-body problem since it provides a good approximation in the vicinity of the Earth-Moon dynamics. Expansion to more refined models will be considered once the problem has been solved for this first approximation. The problem is solved in several steps. First, we consider the time minimal problem since we will use a multiple of it for the minimal fuel consumption problem with fixed time. The techniques used to produce the transfers involve an indirect method based on the necessary optimality condition of the Pontriagyn maximum principle coupled with a continuation method to address the sensitivity of the numerical algorithm to initial values. Time local optimality is verified by computing the Jacobi fields of the Hamiltonian system associated to our optimal control problem to check the second-order conditions of optimality and determine the non-existence of conjugate points.

Visual Odometry for Autonomous Deep-Space Navigation

NASA Technical Reports Server (NTRS)

Robinson, Shane; Pedrotty, Sam

2016-01-01

Visual Odometry fills two critical needs shared by all future exploration architectures considered by NASA: Autonomous Rendezvous and Docking (AR&D), and autonomous navigation during loss of comm. To do this, a camera is combined with cutting-edge algorithms (called Visual Odometry) into a unit that provides accurate relative pose between the camera and the object in the imagery. Recent simulation analyses have demonstrated the ability of this new technology to reliably, accurately, and quickly compute a relative pose. This project advances this technology by both preparing the system to process flight imagery and creating an activity to capture said imagery. This technology can provide a pioneering optical navigation platform capable of supporting a wide variety of future missions scenarios: deep space rendezvous, asteroid exploration, loss-of-comm.

Astrometric observations of comets and asteroids and subsequent orbital investigations

NASA Technical Reports Server (NTRS)

Mccrosky, R. E.; Marsden, B. G.

1986-01-01

During the past year some 500 observations were made on 66 nights and published on the MPCs (Minor Planet Circulars/Minor Planets and Comets). In addition, a handful of measurements of earlier plates were completed and published. 121 of the observations published referred to comets. Of special importance were observations of comets (P/Giacobini-Zinner and P/Halley) in connection with the NASA ICE and ESA Giotto missions, but a special effort was made to get good coverage of almost all of the observable comets. Observations were also made of (2060) Chiron and of the earth-approaching objects (1627) Ivar, (1866) Sisyphys, (1943) Anteros, (3362) 1984 QA, 1985 JA, PA, TB and WA, and 1986 DA and EB. 46 minor planets were given permanent numbers entirely as a result of the observations.

Distant asteroids and Chiron

NASA Technical Reports Server (NTRS)

French, Linda M.; Vilas, Faith; Hartmann, William K.; Tholen, David J.

1989-01-01

Knowledge of the physical properties of distant asteroids (a greater than 3.3 AU) has grown dramatically over the past five years, due to systematic compositional and lighcurve studies. Most of these objects have red, dark surfaces, and their spectra show a reddening in spectral slope with heliocentric distance, implying a change in surface composition. Trojans for which near-opposition phase curve information is available appear to show little or no opposition effect, unlike any other dark solar system objects. The lightcurve amplitudes of Trojan and Hilda asteroids imply significantly more elongated shapes for these groups than for main-belt asteroids of comparable size. These recent observations are reviewed in the context of their implications for the formationan and subsequent evolution of the distant asteroids, and their interrelations with the main belt, Chiron, and comets.

Stardust Worlds

NASA Image and Video Library

2011-03-24

This composite image shows the three small worlds NASA Stardust spacecraft encountered during its 12 year mission. Stardust performed a flyby of asteroid Annefrank in 2002, Comet Wild in 2004, and Tempel 1 in 2011.

Spacewatch Survey for Asteroids and Comets

DTIC Science & Technology

2005-11-01

radar images. Relationship of Spacewatch to the WISE spacecraft mission: E. L. Wright of the UCLA Astronomy Dept. is the PI of the Wide-field Infrared ...Survey Explorer (WISE) MIDEX spacecraft mission. WISE will map the whole sky at thermal infrared wavelengths with 500 times more sensitivity than the...elongations. WISE=s detections in the thermal infrared will also provide a size-limited sample of asteroids instead of the brightness-limited surveys

Asteroid 5535 Annefrank size, shape, and orientation: Stardust first results

NASA Technical Reports Server (NTRS)

Duxbury, T. C.; Newburn, R. L., Jr.; Acton, C. H.; Carranza, E.; McElrath, T. P.; Ryan, R. E.; Synnott, S. P.; You, T. H.; Brownlee, D. E.; Cheuvront, A. R.;

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jewitt, David, E-mail: jewitt@ucla.edu; Department of Physics and Astronomy, UCLA, Los Angeles, CA 90095-1567

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 leavesmore » 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.« less

Migration of Matter from the Edgeworth-Kuiper and Main Asteroid Belts to the Earth

NASA Technical Reports Server (NTRS)

Ipatov. S. I.; Oegerle, William (Technical Monitor)

2002-01-01

The main asteroid belt (MAB), the Edgeworth-Kuiper belt (EKB), and comets belong to the main sources of dust in the Solar System. Most of Jupiter-family comets came from the EKB. Comets can be distracted due to close encounters with planets and the Sun, collisions with small bodies, a nd internal forces. We support the Eneev's idea that the largest objects in the ELB and MAB could be formed directly by the compression of rarefied dust condensations of the protoplanetary cloud but not by the accretion of small (for example, 1-km) planetesimals. The total mass of planetesimals that entered the EKB from the feeding zone of the giant planets during their accumulation could exceed tens of Earth's masses. These planetesimals increased eccentricities of 'local' trans-Neptunian objects (TNOs) and swept most of these TNOs. A small portion of such planetesimals could left beyond Neptune's orbit in highly eccentric orbits. The results of previous investigations of migration and collisional evolution of minor bodies were summarized. Mainly our recent results are presented.

Planetary astronomy program

NASA Technical Reports Server (NTRS)

1977-01-01

A program was developed in which asteroids and two planets, namely, Saturn and Uranus, were investigated. This included: (1) asteroid spectrophotometry; (2) the nature of the Trojan asteroids; (3) an investigation to determine asteroid masses; (4) the photometry, structure, and dynamics of the rings surrounding the planet Saturn; and (5) aerosol distribution in the atmosphere of Uranus. Plans were finalized to obtain observations of the nucleus of the dying comet P/Arend-Rigaux. Further work was accomplished in asteroid data reduction. Data were entered into the TRIAD data file and a program generated classifications for over 560 different asteroids. A photoelectric area scanner was used to obtain UBV scans of the disk of the planet Saturn on several winter and spring nights in 1977. Intensity profiles show pronounced limb brightening in U, moderate limb brightening in B, and limb darkening in V. Narrow band photoelectric area-scanning photometry of the Uranus disk is also reported. Results are given.

KSC-05PD-0128

NASA Technical Reports Server (NTRS)

2005-01-01

KENNEDY SPACE CENTER, FLA. On Launch Pad 17-B, Cape Canaveral Air Force Station, Fla., the Boeing Delta II rocket carrying the Deep Impact spacecraft stands out against an early dawn sky. Scheduled for liftoff at 1:47 p.m. EST today, Deep Impact will head for space and a rendezvous with Comet Tempel 1 when the comet is 83 million miles from Earth. After releasing a 3- by 3-foot projectile (impactor) to crash onto the surface July 4, 2005, Deep Impacts flyby spacecraft will reveal the secrets of the comets interior by collecting pictures and data of how the crater forms, measuring the craters depth and diameter as well as the composition of the interior of the crater and any material thrown out, and determining the changes in natural outgassing produced by the impact. It will send the data back to Earth through the antennas of the Deep Space Network. Deep Impact is a NASA Discovery mission.

KSC-05PD-0124

NASA Technical Reports Server (NTRS)

2005-01-01

KENNEDY SPACE CENTER, FLA. On Launch Pad 17-B, Cape Canaveral Air Force Station, Fla., the Boeing Delta II rocket carrying the Deep Impact spacecraft is bathed in light waiting for tower rollback before launch. Scheduled for liftoff at 1:47 p.m. EST today, Deep Impact will head for space and a rendezvous with Comet Tempel 1 when the comet is 83 million miles from Earth. After releasing a 3- by 3-foot projectile (impactor) to crash onto the surface July 4, 2005, Deep Impacts flyby spacecraft will reveal the secrets of the comets interior by collecting pictures and data of how the crater forms, measuring the craters depth and diameter as well as the composition of the interior of the crater and any material thrown out, and determining the changes in natural outgassing produced by the impact. It will send the data back to Earth through the antennas of the Deep Space Network. Deep Impact is a NASA Discovery mission.

New Hypervelocity Terminal Intercept Guidance Systems for Deflecting/Disrupting Hazardous Asteroids

NASA Astrophysics Data System (ADS)

Lyzhoft, Joshua Richard

Computational modeling and simulations of visual and infrared (IR) sensors are investigated for a new hypervelocity terminal guidance system of intercepting small asteroids (50 to 150 meters in diameter). Computational software tools for signal-to-noise ratio estimation of visual and IR sensors, estimation of minimum and maximum ranges of target detection, and GPU (Graphics Processing Units)-accelerated simulations of the IR-based terminal intercept guidance systems are developed. Scaled polyhedron models of known objects, such as the Rosetta mission's Comet 67P/C-G, NASA's OSIRIS-REx Bennu, and asteroid 433 Eros, are utilized in developing a GPU-based simulation tool for the IR-based terminal intercept guidance systems. A parallelized-ray tracing algorithm for simulating realistic surface-to-surface shadowing of irregular-shaped asteroids or comets is developed. Polyhedron solid-angle approximation is also considered. Using these computational models, digital image processing is investigated to determine single or multiple impact locations to assess the technical feasibility of new planetary defense mission concepts of utilizing a Hypervelocity Asteroid Intercept Vehicle (HAIV) or a Multiple Kinetic-energy Interceptor Vehicle (MKIV). Study results indicate that the IR-based guidance system outperforms the visual-based system in asteroid detection and tracking. When using an IR sensor, predicting impact locations from filtered images resulted in less jittery spacecraft control accelerations than conducting missions with a visual sensor. Infrared sensors have also the possibility to detect asteroids at greater distances, and if properly used, can aid in terminal phase guidance for proper impact location determination for the MKIV system. Emerging new topics of the Minimum Orbit Intersection Distance (MOID) estimation and the Full-Two-Body Problem (F2BP) formulation are also investigated to assess a potential near-Earth object collision risk and the proximity gravity effects of an irregular-shaped binary-asteroid target on a standoff nuclear explosion mission.

Jupiter - Friend or Foe?

NASA Astrophysics Data System (ADS)

Horner, J.; Jones, B. W.

2008-09-01

It has long been believed that the planet Jupiter has played a beneficial role in the development of life on the Earth, acting as a shield from objects which would otherwise go on to significantly raise the impact flux experienced by our planet. Without Jupiter, the story goes, the Earth would have experienced a far greater number of impacts, making it far less hospitable to burgeoning life. In an on-going series of separate studies[1,2], we have examined the effects of varying the mass of Jupiter on the impact flux that the Earth would experience from Near-Earth Objects sourced from the Asteroid belt, short-period comets sourced from the Edgeworth-Kuiper belt, and long-period comets sourced from the Oort cloud. The results are remarkable - it seems that, far from being a shield, Jupiter actually acts to increase the impact flux experienced by the Earth over that which would be expected without the planet. Still more surprising, in the cases of the asteroids and Edgeworth-Kuiper belt objects, it seems that a Jupiter around 0.2 times the mass of "our Jupiter" would be even more threatening, sending a still greater number of objects our way. In order to simulate such disparate populations, different approaches to population construction were needed. The asteroidal and short-period comet populations each contained 100,000 test particles, moving on orbits typical of their class. The asteroids were initially distributed between 2 and 4 AU, with orbits of varying eccentricity and inclination, with number density varying as a function of semi-major axis. The short-period cometary flux was obtained through simulation of a population based on the subset of known Centaurs and Scattered Disk Objects which are Neptune-crossing, and have perihelia beyond the orbit of Uranus. These objects are the parents of the short-period comets, and were chosen since they are a population beyond the current influence of the planet Jupiter. Since our goal was to study the effect of Jupiter's mass on the impact flux at the Earth from the two populations, we followed our 100,000 particle populations for 10 million years, under the influence of the giant planets. Each particle was followed until it either hit something, or was ejected from the system. In this manner, we were able to follow the flux of objects onto the Earth as a function of time. The simulations were repeated over a wide range of Jupiter masses, with all other variables being held constant, allowing us to observe the variations in impact flux as a function of Jovian mass. In the cases of the asteroids and the short-period comets, Jupiter was observed to significantly modify the impact flux which would be experienced by the planet Earth. It was immediately obvious, however, that the old idea that Jupiter shields us from impacts no longer holds. For both of these populations, the lowest impact rates were experienced when the Jupiter-like planet in the system had the lowest mass, rose rapidly to a peak flux at around 0.2 Jupiter masses, before falling away more slowly. Therefore, for the asteroids and short-period comets, it seems that our Jupiter does offer some shielding, when compared to the case where the planet has a mass of around 0.2 MJ, but, compared to the scenario where no Jupiter is present at all (or the Jupiter in question has very low mass), Jupiter actually acts to increase the Earth-bound flux. Simulations are currently underway with the goal of analysing the effects of Jupiter's mass on the impact flux from the long-period comets (deflected inward towards the Earth from the Oort cloud). Further into the future, we intend to study the effects of Jovian position of the impact flux, with the goal of answering, once and for all, the question - "Jupiter - Friend or Foe?".

The Ion Propulsion System for the Asteroid Redirect Robotic Mission

NASA Technical Reports Server (NTRS)

Herman, Daniel A.; Santiago, Walter; Kamhawi, Hani; Polk, James E.; Snyder, John Steven; Hofer, Richard R.; Sekerak, Michael J.

2016-01-01

The Asteroid Redirect Robotic Mission is a Solar Electric Propulsion Technology Demonstration Mission (ARRM) whose main objectives are to develop and demonstrate a high-power solar electric propulsion capability for the Agency and return an asteroidal mass for rendezvous and characterization in a companion human-crewed mission. This high-power solar electric propulsion capability, or an extensible derivative of it, has been identified as a critical part of NASA'a future beyond-low-Earth-orbit, human-crewed exploration plans. Under the NASA Space Technology Mission Directorate the critical electric propulsion and solar array technologies are being developed. This paper presents the conceptual design of the ARRM ion propulsion system, the status of the NASA in-house thruster and power processing development activities, the status of the planned technology maturation for the mission through flight hardware delivery, and the status of the mission formulation and spacecraft acquisition.

Human Exploration of Near-Earth Asteroids

NASA Technical Reports Server (NTRS)

Abell, Paul

2013-01-01

A major goal for NASA's human spaceflight program is to send astronauts to near-Earth asteroids (NEA) in the coming decades. Missions to NEAs would undoubtedly provide a great deal of technical and engineering data on spacecraft operations for future human space exploration while conducting in-depth scientific examinations of these primitive objects. However, before sending human explorers to NEAs, robotic investigations of these bodies would be required to maximize operational efficiency and reduce mission risk. These precursor missions to NEAs would fill crucial strategic knowledge gaps concerning their physical characteristics that are relevant for human exploration of these relatively unknown destinations. Dr. Paul Abell discussed some of the physical characteristics of NEOs that will be relevant for EVA considerations, reviewed the current data from previous NEA missions (e.g., Near-Earth Asteroid Rendezvous (NEAR) Shoemaker and Hayabusa), and discussed why future robotic and human missions to NEAs are important from space exploration and planetary defense perspectives.

Mars, Phobos, and Deimos Sample Return Enabled by ARRM Alternative Trade Study Spacecraft

NASA Technical Reports Server (NTRS)

Englander, Jacob A.; Vavrina, Matthew; Merrill, Raymond G.; Qu, Min; Naasz, Bo J.

2014-01-01

The Asteroid Robotic Redirect Mission (ARRM) has been the topic of many mission design studies since 2011. The reference ARRM spacecraft uses a powerful solar electric propulsion (SEP) system and a bag device to capture a small asteroid from an Earth-like orbit and redirect it to a distant retrograde orbit (DRO) around the moon. The ARRM Option B spacecraft uses the same propulsion system and multi-Degree of Freedom (DoF) manipulators device to retrieve a very large sample (thousands of kilograms) from a 100+ meter diameter farther-away Near Earth Asteroid (NEA). This study will demonstrate that the ARRM Option B spacecraft design can also be used to return samples from Mars and its moons - either by acquiring a large rock from the surface of Phobos or Deimos, and or by rendezvousing with a sample-return spacecraft launched from the surface of Mars.

Mars, Phobos, and Deimos Sample Return Enabled by ARRM Alternative Trade Study Spacecraft

NASA Technical Reports Server (NTRS)

Englander, Jacob A.; Vavrina, Matthew; Naasz, Bo; Merill, Raymond G.; Qu, Min

2014-01-01

The Asteroid Robotic Redirect Mission (ARRM) has been the topic of many mission design studies since 2011. The reference ARRM spacecraft uses a powerful solar electric propulsion (SEP) system and a bag device to capture a small asteroid from an Earth-like orbit and redirect it to a distant retrograde orbit (DRO) around the moon. The ARRM Option B spacecraft uses the same propulsion system and multi-Degree of Freedom (DoF) manipulators device to retrieve a very large sample (thousands of kilograms) from a 100+ meter diameter farther-away Near Earth Asteroid (NEA). This study will demonstrate that the ARRM Option B spacecraft design can also be used to return samples from Mars and its moons - either by acquiring a large rock from the surface of Phobos or Deimos, and/or by rendezvousing with a sample-return spacecraft launched from the surface of Mars.

Research in planetary studies and operation of the Mauna Kea Observatory

NASA Technical Reports Server (NTRS)

Cruikshank, Dale P.

1986-01-01

The research programs are highlighted in the following areas: major planets; planetary satellites and rings; asteroids; comets; dark organic matter; theoretical and analytical structures; extrasolar planetary; and telescopes.

Alien Sunset Artist Concept

NASA Image and Video Library

2007-03-29

Observations from NASA Spitzer Space Telescope have revealed that mature planetary systems -- dusty disks of asteroids, comets and possibly planets -- are more frequent around close-knit twin, or binary, stars than single stars like our sun.

Reduction of astrometric plates

NASA Technical Reports Server (NTRS)

Stock, J.

1984-01-01

A rapid and accurate method for the reduction of comet or asteroid plates is described. Projection equations, scale length correction, rotation of coordinates, linearization, the search for additional reference stars, and the final solution are examined.

Operation of the University of Hawaii 2.2M Telescope on Mauna Kea

NASA Technical Reports Server (NTRS)

McLaren, Robert A.

1999-01-01

This paper presents a final report from March 1, 1997-February 28, 1999 on the Operation of the University of Hawaii 2.2M Telescope on Mauna Kea. The topics include: 1) Telescope and Instrumentation (Newsletter and Documentation, Scheduling Periods); and 2) Scientific Highlights (The Outer Solar System-Trans-Neptunian Objects and the Kuiper Belt, Comet Hale-Bopp, Near-Earth Asteroids, Asteroid Families, and Galileo Mission Support).

Preliminary Results from NEOWISE: An Enhancement to the Wide-field Infrared Survey Explorer for Solar System Science

NASA Astrophysics Data System (ADS)

Mainzer, A.; Bauer, J.; Grav, T.; Masiero, J.; Cutri, R. M.; Dailey, J.; Eisenhardt, P.; McMillan, R. S.; Wright, E.; Walker, R.; Jedicke, R.; Spahr, T.; Tholen, D.; Alles, R.; Beck, R.; Brandenburg, H.; Conrow, T.; Evans, T.; Fowler, J.; Jarrett, T.; Marsh, K.; Masci, F.; McCallon, H.; Wheelock, S.; Wittman, M.; Wyatt, P.; DeBaun, E.; Elliott, G.; Elsbury, D.; Gautier, T., IV; Gomillion, S.; Leisawitz, D.; Maleszewski, C.; Micheli, M.; Wilkins, A.

2011-04-01

The Wide-field Infrared Survey Explorer (WISE) has surveyed the entire sky at four infrared wavelengths with greatly improved sensitivity and spatial resolution compared to its predecessors, the Infrared Astronomical Satellite and the Cosmic Background Explorer. NASA's Planetary Science Division has funded an enhancement to the WISE data processing system called "NEOWISE" that allows detection and archiving of moving objects found in the WISE data. NEOWISE has mined the WISE images for a wide array of small bodies in our solar system, including near-Earth objects (NEOs), Main Belt asteroids, comets, Trojans, and Centaurs. By the end of survey operations in 2011 February, NEOWISE identified over 157,000 asteroids, including more than 500 NEOs and ~120 comets. The NEOWISE data set will enable a panoply of new scientific investigations.

Multiple NEO Rendezvous Using Solar Sail Propulsion

NASA Technical Reports Server (NTRS)

Johnson, Les; Alexander, Leslie; Fabisinski, Leo; Heaton, Andy; Miernik, Janie; Stough, Rob; Wright, Roosevelt; Young, Roy

2012-01-01

The NASA Marshall Space Flight Center (MSFC) Advanced Concepts Office performed an assessment of the feasibility of using a near-term solar sail propulsion system to enable a single spacecraft to perform serial rendezvous operations at multiple Near Earth Objects (NEOs) within six years of launch on a small-to-moderate launch vehicle. The study baselined the use of the sail technology demonstrated in the mid-2000 s by the NASA In-Space Propulsion Technology Project and is scheduled to be demonstrated in space by 2014 as part of the NASA Technology Demonstration Mission Program. The study ground rules required that the solar sail be the only new technology on the flight; all other spacecraft systems and instruments must have had previous space test and qualification. The resulting mission concept uses an 80-m X 80-m 3-axis stabilized solar sail launched by an Athena-II rocket in 2017 to rendezvous with 1999 AO10, Apophis and 2001 QJ142. In each rendezvous, the spacecraft will perform proximity operations for approximately 30 days. The spacecraft science payload is simple and lightweight; it will consist of only the multispectral imager flown on the Near Earth Asteroid Rendezvous (NEAR) mission to 433 Eros and 253 Mathilde. Most non-sail spacecraft systems are based on the Messenger mission spacecraft. This paper will describe the objectives of the proposed mission, the solar sail technology to be employed, the spacecraft system and subsystems, as well as the overall mission profile.

Reactive Sequencing for Autonomous Navigation Evolving from Phoenix Entry, Descent, and Landing

NASA Technical Reports Server (NTRS)

Grasso, Christopher A.; Riedel, Joseph E.; Vaughan, Andrew T.

2010-01-01

Virtual Machine Language (VML) is an award-winning advanced procedural sequencing language in use on NASA deep-space missions since 1997, and was used for the successful entry, descent, and landing (EDL) of the Phoenix spacecraft onto the surface of Mars. Phoenix EDL utilized a state-oriented operations architecture which executed within the constraints of the existing VML 2.0 flight capability, compatible with the linear "land or die" nature of the mission. The intricacies of Phoenix EDL included the planned discarding of portions of the vehicle, the complex communications management for relay through on-orbit assets, the presence of temporally indeterminate physical events, and the need to rapidly catch up four days of sequencing should a reboot of the spacecraft flight computer occur shortly before atmospheric entry. These formidable operational challenges led to new techniques for packaging and coordinating reusable sequences called blocks using one-way synchronization via VML sequencing global variable events. The coordinated blocks acted as an ensemble to land the spacecraft, while individually managing various elements in as simple a fashion as possible. This paper outlines prototype VML 2.1 flight capabilities that have evolved from the one-way synchronization techniques in order to implement even more ambitious autonomous mission capabilities. Target missions for these new capabilities include autonomous touch-and-go sampling of cometary and asteroidal bodies, lunar landing of robotic missions, and ultimately landing of crewed lunar vehicles. Close proximity guidance, navigation, and control operations, on-orbit rendezvous, and descent and landing events featured in these missions require elaborate abort capability, manifesting highly non-linear scenarios that are so complex as to overtax traditional sequencing, or even the sort of one-way coordinated sequencing used during EDL. Foreseeing advanced command and control needs for small body and lunar landing guidance, navigation and control scenarios, work began three years ago on substantial upgrades to VML that are now being exercised in scenarios for lunar landing and comet/asteroid rendezvous. The advanced state-based approach includes coordinated state transition machines with distributed decision-making logic. These state machines are not merely sequences - they are reactive logic constructs capable of autonomous decision making within a well-defined domain. Combined with the JPL's AutoNav software used on Deep Space 1 and Deep Impact, the system allows spacecraft to autonomously navigate to an unmapped surface, soft-contact, and either land or ascend. The state machine architecture enabled by VML 2.1 has successfully performed sampling missions and lunar descent missions in a simulated environment, and is progressing toward flight capability. The authors are also investigating using the VML 2.1 flight director architecture to perform autonomous activities like rendezvous with a passive hypothetical Mars sample return capsule. The approach being pursued is similar to the touch-and-go sampling state machines, with the added complications associated with the search for, physical capture of, and securing of a separate spacecraft. Complications include optically finding and tracking the Orbiting Sample Capsule (OSC), keeping the OSC illuminated, making orbital adjustments, and physically capturing the OSC. Other applications could include autonomous science collection and fault compensation.

Chondrulelike objects in short-period comet 81P/Wild 2.

PubMed

Nakamura, Tomoki; Noguchi, Takaaki; Tsuchiyama, Akira; Ushikubo, Takayuki; Kita, Noriko T; Valley, John W; Zolensky, Michael E; Kakazu, Yuki; Sakamoto, Kanako; Mashio, Etsuko; Uesugi, Kentaro; Nakano, Tsukasa

2008-09-19

The Stardust spacecraft returned cometary samples that contain crystalline material, but the origin of the material is not yet well understood. We found four crystalline particles from comet 81P/Wild 2 that were apparently formed by flash-melting at a high temperature and are texturally, mineralogically, and compositionally similar to chondrules. Chondrules are submillimeter particles that dominate chondrites and are believed to have formed in the inner solar nebula. The comet particles show oxygen isotope compositions similar to chondrules in carbonaceous chondrites that compose the middle-to-outer asteroid belt. The presence of the chondrulelike objects in the comet suggests that chondrules have been transported out to the cold outer solar nebula and spread widely over the early solar system.

The population, magnitudes, and sizes of Jupiter family comets

NASA Astrophysics Data System (ADS)

Fernández, J. A.; Tancredi, G.; Rickman, H.; Licandro, J.

1999-12-01

We analyze the sample of measured nuclear magnitudes of the observed Jupiter family (JF) comets (taken as those with orbital periods P < 20 years and Tisserand parameters T > 2). We find a tendency of the measured nuclear magnitudes to be fainter as JF comets are observed with CCD detectors attached to medium- and large-size telescopes (e.g. Spacewatch Telescope). However, a few JF comets observed very far from the Sun (4-7 AU) show a wide dispersion of their derived absolute nuclear magnitudes which suggests that either these JF comets keep active all along the orbit, so the reported unusually bright distant magnitudes were strongly contaminated by a coma, or some of the measured ``nuclear magnitudes'' were grossly overestimated (i.e. their brightness underestimated). The cumulative mass distribution of JF comets is found to follow a power-law of index s = - 0.88 +/- 0.08, suggesting a distribution significantly steeper than that for both small main-belt asteroids and near-Earth asteroids. The cumulative mass distribution of JF comets with q < 2 AU tends to flatten for absolute (visual) nuclear magnitudes H_N > 16, which is probably due to incompleteness of discovery of fainter comets and/or a real scarcity of small comets due, perhaps, to much shorter physical lifetimes. In particular, no JF comets fainter than H_N ~ 19.5 are found in the sample, suggesting that the critical size for a comet to be still active may be of about 0.4 km radius for an assumed geometric albedo of 0.04. Possibly, smaller comet nuclei disintegrate very quickly into meteor streams. Most absolute nuclear magnitudes are found in the range 15-18, corresponding to nuclear radii in the range 0.8-3.3 km (for the same geometric albedo). We find that a large majority of JF comets with perihelion distances q > 2.5 AU are brighter than absolute nuclear magnitude H_N = 16, suggesting that only a very small fraction (a few percent) of the population of the JF comets with large q has so far been detected. A similar trend is noted for the corresponding absolute total magnitudes H_T taken from Kresák & Kresáková's (1994) catalog. By analyzing the H_N and H_T data, and trends in the discovery rate of JF comets as a function of their perihelion distances, the overall population of JF comets within Jupiter's region (q < 5.2 AU) up to an absolute nuclear magnitude H_N = 18.5 is estimated to be from several thousand to about 104 members. The q-distribution of JF comets shows a steep increase with q, which is consistent with JF comets coming from a flat intermediate source in the Jupiter-Saturn region.

Integrated Attitude Control Strategy for the Asteroid Redirect Mission

NASA Technical Reports Server (NTRS)

Lopez, Pedro, Jr.; Price, Hoppy; San Martin, Miguel

2014-01-01

A deep-space mission has been proposed to redirect an asteroid to a distant retrograde orbit around the moon using a robotic vehicle, the Asteroid Redirect Vehicle (ARV). In this orbit, astronauts will rendezvous with the ARV using the Orion spacecraft. The integrated attitude control concept that Orion will use for approach and docking and for mated operations will be described. Details of the ARV's attitude control system and its associated constraints for redirecting the asteroid to the distant retrograde orbit around the moon will be provided. Once Orion is docked to the ARV, an overall description of the mated stack attitude during all phases of the mission will be presented using a coordinate system that was developed for this mission. Next, the thermal and power constraints of both the ARV and Orion will be discussed as well as how they are used to define the optimal integrated stack attitude. Lastly, the lighting and communications constraints necessary for the crew's extravehicular activity planned to retrieve samples from the asteroid will be examined. Similarly, the joint attitude control strategy that employs both the Orion and the ARV attitude control assets prior, during, and after each extravehicular activity will also be thoroughly discussed.

Active Asteroids in the NEO Population

NASA Astrophysics Data System (ADS)

Jenniskens, Peter

2016-01-01

Some main-belt asteroids evolve into near-Earth objects. They can then experience the same meteoroid-producing phenomena as active asteroids in the main belt. If so, they would produce meteoroid streams, some of which evolve to intersect Earth's orbit and produce meteor showers at Earth. Only few of those are known. Meteoroid streams that move in orbits with Tisserand parameter well in excess of 3 are the Geminids and Daytime Sextantids of the Phaethon complex and the lesser known epsilon Pegasids. The observed activity appears to be related to nearly whole scale disintegrations, rather than dust ejection from volatile outgassing as observed in active comets. There is only a small population of asteroids with a main-belt origin that recently disintegrated into meteoroid streams.

Secular orbital evolution of Jupiter family comets

NASA Astrophysics Data System (ADS)

Rickman, H.; Gabryszewski, R.; Wajer, P.; Wiśniowski, T.; Wójcikowski, K.; Szutowicz, S.; Valsecchi, G. B.; Morbidelli, A.

2017-02-01

Context. The issue of the long term dynamics of Jupiter family comets (JFCs) involves uncertain assumptions about the physical evolution and lifetimes of these comets. Contrary to what is often assumed, real effects of secular dynamics cannot be excluded and therefore merit investigation. Aims: We use a random sample of late heavy bombardment cometary projectiles to study the long-term dynamics of JFCs by a Monte Carlo approach. In a steady-state picture of the Jupiter family, we investigate the orbital distribution of JFCs, including rarely visited domains like retrograde orbits or orbits within the outer parts of the asteroid main belt. Methods: We integrate 100 000 objects over a maximum of 100 000 orbital revolutions including the Sun, a comet, and four giant planets. Considering the steady-state number of JFCs to be proportional to the total time spent in the respective orbital domain, we derive the capture rate based on observed JFCs with small perihelia and large nuclei. We consider a purely dynamical model and one where the nuclei are eroded by ice sublimation. Results: The JFC inclination distribution is incompatible with our erosional model. This may imply that a new type of comet evolution model is necessary. Considering that comets may live for a long time, we show that JFCs can evolve into retrograde orbits as well as asteroidal orbits in the outer main belt or Cybele regions. The steady-state capture rate into the Jupiter family is consistent with 1 × 109 scattered disk objects with diameters D > 2 km. Conclusions: Our excited scattered disk makes it difficult to explain the JFC inclination distribution, unless the physical evolution of JFCs is more intricate than assumed in standard, erosional models. Independent of this, the population size of the Jupiter family is consistent with a relatively low-mass scattered disk.

The comet-like composition of a protoplanetary disk as revealed by complex cyanides.

PubMed

Öberg, Karin I; Guzmán, Viviana V; Furuya, Kenji; Qi, Chunhua; Aikawa, Yuri; Andrews, Sean M; Loomis, Ryan; Wilner, David J

2015-04-09

Observations of comets and asteroids show that the solar nebula that spawned our planetary system was rich in water and organic molecules. Bombardment brought these organics to the young Earth's surface. Unlike asteroids, comets preserve a nearly pristine record of the solar nebula composition. The presence of cyanides in comets, including 0.01 per cent of methyl cyanide (CH3CN) with respect to water, is of special interest because of the importance of C-N bonds for abiotic amino acid synthesis. Comet-like compositions of simple and complex volatiles are found in protostars, and can readily be explained by a combination of gas-phase chemistry (to form, for example, HCN) and an active ice-phase chemistry on grain surfaces that advances complexity. Simple volatiles, including water and HCN, have been detected previously in solar nebula analogues, indicating that they survive disk formation or are re-formed in situ. It has hitherto been unclear whether the same holds for more complex organic molecules outside the solar nebula, given that recent observations show a marked change in the chemistry at the boundary between nascent envelopes and young disks due to accretion shocks. Here we report the detection of the complex cyanides CH3CN and HC3N (and HCN) in the protoplanetary disk around the young star MWC 480. We find that the abundance ratios of these nitrogen-bearing organics in the gas phase are similar to those in comets, which suggests an even higher relative abundance of complex cyanides in the disk ice. This implies that complex organics accompany simpler volatiles in protoplanetary disks, and that the rich organic chemistry of our solar nebula was not unique.

The comet-like composition of a protoplanetary disk as revealed by complex cyanides

NASA Astrophysics Data System (ADS)

Öberg, Karin I.; Guzmán, Viviana V.; Furuya, Kenji; Qi, Chunhua; Aikawa, Yuri; Andrews, Sean M.; Loomis, Ryan; Wilner, David J.

2015-04-01

Observations of comets and asteroids show that the solar nebula that spawned our planetary system was rich in water and organic molecules. Bombardment brought these organics to the young Earth's surface. Unlike asteroids, comets preserve a nearly pristine record of the solar nebula composition. The presence of cyanides in comets, including 0.01 per cent of methyl cyanide (CH3CN) with respect to water, is of special interest because of the importance of C-N bonds for abiotic amino acid synthesis. Comet-like compositions of simple and complex volatiles are found in protostars, and can readily be explained by a combination of gas-phase chemistry (to form, for example, HCN) and an active ice-phase chemistry on grain surfaces that advances complexity. Simple volatiles, including water and HCN, have been detected previously in solar nebula analogues, indicating that they survive disk formation or are re-formed in situ. It has hitherto been unclear whether the same holds for more complex organic molecules outside the solar nebula, given that recent observations show a marked change in the chemistry at the boundary between nascent envelopes and young disks due to accretion shocks. Here we report the detection of the complex cyanides CH3CN and HC3N (and HCN) in the protoplanetary disk around the young star MWC 480. We find that the abundance ratios of these nitrogen-bearing organics in the gas phase are similar to those in comets, which suggests an even higher relative abundance of complex cyanides in the disk ice. This implies that complex organics accompany simpler volatiles in protoplanetary disks, and that the rich organic chemistry of our solar nebula was not unique.

NASA Study Hints at Possible Change in Water ‘Fingerprint’ of Comet

NASA Image and Video Library

2017-12-08

A trip past the sun may have selectively altered the production of one form of water in a comet – an effect not seen by astronomers before, a new NASA study suggests. Astronomers from NASA’s Goddard Space Flight Center in Greenbelt, Maryland, observed the Oort cloud comet C/2014 Q2, also called Lovejoy, when it passed near Earth in early 2015. Through NASA’s partnership in the W. M. Keck Observatory on Mauna Kea, Hawaii, the team observed the comet at infrared wavelengths a few days after Lovejoy passed its perihelion – or closest point to the sun. The team focused on Lovejoy’s water, simultaneously measuring the release of H2O along with production of a heavier form of water, HDO. Water molecules consist of two hydrogen atoms and one oxygen atom. A hydrogen atom has one proton, but when it also includes a neutron, that heavier hydrogen isotope is called deuterium, or the “D” in HDO. From these measurements, the researchers calculated the D-to-H ratio – a chemical fingerprint that provides clues about exactly where comets (or asteroids) formed within the cloud of material that surrounded the young sun in the early days of the solar system. Researchers also use the D-to-H value to try to understand how much of Earth’s water may have come from comets versus asteroids. Read more: go.nasa.gov/2lvd6Vt NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Near Earth Asteroid Rendezvous (NEAR) Revised Eros Orbit Phase Trajectory Design

NASA Technical Reports Server (NTRS)

Helfrich, J; Miller, J. K.; Antreasian, P. G.; Carranza, E.; Williams, B. G.; Dunham, D. W.; Farquhar, R. W.; McAdams, J. V.

1999-01-01

Trajectory design of the orbit phase of the NEAR mission involves a new process that departs significantly from those procedures used in previous missions. In most cases, a precise spacecraft ephemeris is designed well in advance of arrival at the target body. For NEAR, the uncertainty in the dynamic environment around Eros does not allow the luxury of a precise spacecraft trajectory to be defined in advance. The principal cause of this uncertainty is the limited knowledge oi' the gravity field a,-id rotational state of Eros. As a result, the concept for the NEAR trajectory design is to define a number of rules for satisfying spacecraft, mission, and science constraints, and then apply these rules to various assumptions for the model of Eros. Nominal, high, and low Eros mass models are used for testing the trajectory design strategy and to bracket the ranges of parameter variations that are expected upon arrival at the asteroid. The final design is completed after arrival at Eros and determination of the actual gravity field and rotational state. As a result of the unplanned termination of the deep space rendezvous maneuver on December 20, 1998, the NEAR spacecraft passed within 3830 km of Eros on December 23, 1998. This flyby provided a brief glimpse of Eros, and allowed for a more accurate model of the rotational parameters and gravity field uncertainty. Furthermore, after the termination of the deep space rendezvous burn, contact with the spacecraft was lost and the NEAR spacecraft lost attitude control. During the subsequent gyrations of the spacecraft, hydrazine thruster firings were used to regain attitude control. This unplanned thruster activity used Much of the fuel margin allocated for the orbit phase. Consequently, minimizing fuel consumption is now even more important.

AIDA DART asteroid deflection test: Planetary defense and science objectives

NASA Astrophysics Data System (ADS)

Cheng, Andrew F.; Rivkin, Andrew S.; Michel, Patrick; Atchison, Justin; Barnouin, Olivier; Benner, Lance; Chabot, Nancy L.; Ernst, Carolyn; Fahnestock, Eugene G.; Kueppers, Michael; Pravec, Petr; Rainey, Emma; Richardson, Derek C.; Stickle, Angela M.; Thomas, Cristina

2018-08-01

The Asteroid Impact & Deflection Assessment (AIDA) mission is an international cooperation between NASA and ESA. NASA plans to provide the Double Asteroid Redirection Test (DART) mission which will perform a kinetic impactor experiment to demonstrate asteroid impact hazard mitigation. ESA proposes to provide the Hera mission which will rendezvous with the target to monitor the deflection, perform detailed characterizations, and measure the DART impact outcomes and momentum transfer efficiency. The primary goals of AIDA are (i) to demonstrate the kinetic impact technique on a potentially hazardous near-Earth asteroid and (ii) to measure and characterize the deflection caused by the impact. The AIDA target will be the binary asteroid (65803) Didymos, which is of spectral type Sq, with the deflection experiment to occur in October, 2022. The DART impact on the secondary member of the binary at ∼6 km/s changes the orbital speed and the binary orbit period, which can be measured by Earth-based observatories with telescope apertures as small as 1 m. The DART impact will in addition alter the orbital and rotational states of the Didymos binary, leading to excitation of eccentricity and libration that, if measured by Hera, can constrain internal structure of the target asteroid. Measurements of the DART crater diameter and morphology can constrain target properties like cohesion and porosity based on numerical simulations of the DART impact.

Technology Development of Automated Rendezvous and Docking/Capture Sensors and Docking Mechanism for the Asteroid Redirect Crewed Mission

NASA Technical Reports Server (NTRS)

Hinkel, Heather; Cryan, Scott; Zipay, John; Strube, Matthew

2015-01-01

This paper will describe the technology development efforts NASA has underway for Automated Rendezvous and Docking/Capture (AR&D/C) sensors and a docking mechanism and the challenges involved. The paper will additionally address how these technologies will be extended to other missions requiring AR&D/C whether robotic or manned. NASA needs AR&D/C sensors for both the robotic and crewed segments of the Asteroid Redirect Mission (ARM). NASA recently conducted a commonality assessment of the concept of operations for the robotic Asteroid Redirect Vehicle (ARV) and the crewed mission segment using the Orion crew vehicle. The commonality assessment also considered several future exploration and science missions requiring an AR&D/C capability. Missions considered were asteroid sample return, satellite servicing, and planetary entry, descent, and landing. This assessment determined that a common sensor suite consisting of one or more visible wavelength cameras, a threedimensional LIDAR along with long-wavelength infrared cameras for robustness and situational awareness could be used on each mission to eliminate the cost of multiple sensor developments and qualifications. By choosing sensor parameters at build time instead of at design time and, without having to requalify flight hardware, a specific mission can design overlapping bearing, range, relative attitude, and position measurement availability to suit their mission requirements with minimal nonrecurring engineering costs. The resulting common sensor specification provides the union of all performance requirements for each mission and represents an improvement over the current systems used for AR&D/C today. These sensor specifications are tightly coupled to the docking system capabilities and requirements for final docking conditions. The paper will describe NASA's efforts to develop a standard docking system for use across NASA human spaceflight missions to multiple destinations. It will describe the current design status and the considerations and technologies involved in developing this docking mechanism.

Technology Development of Automated Rendezvous and Docking/Capture Sensors and Docking Mechanism for the Asteroid Redirect Crewed Mission

NASA Technical Reports Server (NTRS)

Hinkel, Heather; Strube, Matthew; Zipay, John J.; Cryan, Scott

2015-01-01

This paper will describe the technology development efforts NASA has underway for Automated Rendezvous and Docking/Capture (AR and D/C) sensors and a docking mechanism and the challenges involved. The paper will additionally address how these technologies will be extended to other missions requiring AR and D/C whether robotic or manned. NASA needs AR&D/C sensors for both the robotic and crewed segments of the Asteroid Redirect Mission (ARM). NASA recently conducted a commonality assessment of the concept of operations for the robotic Asteroid Redirect Vehicle (ARV) and the crewed mission segment using the Orion crew vehicle. The commonality assessment also considered several future exploration and science missions requiring an AR and D/C capability. Missions considered were asteroid sample return, satellite servicing, and planetary entry, descent, and landing. This assessment determined that a common sensor suite consisting of one or more visible wavelength cameras, a threedimensional LIDAR along with long-wavelength infrared cameras for robustness and situational awareness could be used on each mission to eliminate the cost of multiple sensor developments and qualifications. By choosing sensor parameters at build time instead of at design time and, without having to requalify flight hardware, a specific mission can design overlapping bearing, range, relative attitude, and position measurement availability to suit their mission requirements with minimal nonrecurring engineering costs. The resulting common sensor specification provides the union of all performance requirements for each mission and represents an improvement over the current systems used for AR and D/C today. These sensor specifications are tightly coupled to the docking system capabilities and requirements for final docking conditions. The paper will describe NASA's efforts to develop a standard docking system for use across NASA human spaceflight missions to multiple destinations. It will describe the current design status and the considerations and technologies involved in developing this docking mechanism.

Technology Development of Automated Rendezvous and Docking/Capture Sensors and Docking Mechanism for the Asteroid Redirect Crewed Mission

NASA Technical Reports Server (NTRS)

Hinkel, Heather; Strube, Matthew; Zipay, John J.; Cryan, Scott

2016-01-01

This paper will describe the technology development efforts NASA has underway for Automated Rendezvous and Docking/Capture (AR&D/C) sensors and a docking mechanism and the challenges involved. The paper will additionally address how these technologies will be extended to other missions requiring AR&D/C whether robotic or manned. NASA needs AR&D/C sensors for both the robotic and crewed segments of the Asteroid Redirect Mission (ARM). NASA recently conducted a commonality assessment of the concept of operations for the robotic Asteroid Redirect Vehicle (ARV) and the crewed mission segment using the Orion spacecraft. The commonality assessment also considered several future exploration and science missions requiring an AR&D/C capability. Missions considered were asteroid sample return, satellite servicing, and planetary entry, descent, and landing. This assessment determined that a common sensor suite consisting of one or more visible wavelength cameras, a three-dimensional LIDAR along with long-wavelength infrared cameras for robustness and situational awareness could be used on each mission to eliminate the cost of multiple sensor developments and qualifications. By choosing sensor parameters at build-time instead of at design-time and, without having to requalify flight hardware, a specific mission can design overlapping bearing, range, relative attitude, and position measurement availability to suit their mission requirements with minimal non-recurring engineering costs. The resulting common sensor specification provides the union of all performance requirements for each mission and represents an improvement over the current systems used for AR&D/C today. These sensor specifications are tightly coupled to the docking system capabilities and requirements for final docking conditions. The paper will describe NASA's efforts to develop a standard docking system for use across NASA human spaceflight missions to multiple destinations. It will describe the current design status and the considerations and technologies involved in developing this docking mechanism.

Rendezvous with Toutatis from the Moon: The Chang'e-2 mission

NASA Astrophysics Data System (ADS)

Huang, J.; Tang, X.; Meng, L.

2014-07-01

Chang'e-2 probe was the second lunar probe of China, with the main objectives to demonstrate some key features of the new lunar soft landing technology, and its applications to future exploration missions. After completing the planned mission successfully, Chang'e-2 flew away from the Moon and entered into the interplanetary space. Later, at a distance of 7 million km from the Earth, Chang'e-2 encountered asteroid (4179) Toutatis with a very close fly-by distance and obtained colorful images with a 3-m resolution. Given some surplus velocity increment as well as the promotion of autonomous flight ability and improvement of control, propulsion, and thermal systems in the initial design, Chang'e-2 had the capabilities necessary for escaping from the Moon. By taking advantage of the unique features of the Lagrangian point, the first close fly-by of asteroid Toutatis was realized despite the tight constraints of propellant allocation, spacecraft-Earth communication, and coordination of execution sequences. Chang'e-2 realized the Toutatis flyby with a km-level distance at closest approach. In the absence of direct measurement method, based on the principle of relative navigation and through the use of the sequence of target images, we calculated the rendezvous parameters such as relative distance and image resolution. With the help of these parameters, some fine and new scientific discoveries about the asteroid were obtained by techniques of optical measurements and image processing. Starting with an innovative design, followed by high-fidelity testing and demonstration, elaborative implementation, and optimal usage of residual propellant, Chang'e-2 has for the first time successfully explored the Moon, L2 point and an asteroid, while achieving the purpose of 'faster, better, cheaper'. What Chang'e-2 has accomplished was far beyond our expectations. *J. Huang is the chief designer (PI) of Chang'e-2 probe, planned Chang'e-2's multi-objective and multitasking exploration mission.

Solar System Science with LSST

NASA Astrophysics Data System (ADS)

Jones, R. L.; Chesley, S. R.; Connolly, A. J.; Harris, A. W.; Ivezic, Z.; Knezevic, Z.; Kubica, J.; Milani, A.; Trilling, D. E.

2008-09-01

The Large Synoptic Survey Telescope (LSST) will provide a unique tool to study moving objects throughout the solar system, creating massive catalogs of Near Earth Objects (NEOs), asteroids, Trojans, TransNeptunian Objects (TNOs), comets and planetary satellites with well-measured orbits and high quality, multi-color photometry accurate to 0.005 magnitudes for the brightest objects. In the baseline LSST observing plan, back-to-back 15-second images will reach a limiting magnitude as faint as r=24.7 in each 9.6 square degree image, twice per night; a total of approximately 15,000 square degrees of the sky will be imaged in multiple filters every 3 nights. This time sampling will continue throughout each lunation, creating a huge database of observations. Fig. 1 Sky coverage of LSST over 10 years; separate panels for each of the 6 LSST filters. Color bars indicate number of observations in filter. The catalogs will include more than 80% of the potentially hazardous asteroids larger than 140m in diameter within the first 10 years of LSST operation, millions of main-belt asteroids and perhaps 20,000 Trans-Neptunian Objects. Objects with diameters as small as 100m in the Main Belt and <100km in the Kuiper Belt can be detected in individual images. Specialized `deep drilling' observing sequences will detect KBOs down to 10s of kilometers in diameter. Long period comets will be detected at larger distances than previously possible, constrainting models of the Oort cloud. With the large number of objects expected in the catalogs, it may be possible to observe a pristine comet start outgassing on its first journey into the inner solar system. By observing fields over a wide range of ecliptic longitudes and latitudes, including large separations from the ecliptic plane, not only will these catalogs greatly increase the numbers of known objects, the characterization of the inclination distributions of these populations will be much improved. Derivation of proper elements for main belt and Trojan asteroids will allow ever more resolution of asteroid families and their size-frequency distribution, as well as the study of the long-term dynamics of the individual asteroids and the asteroid belt as a whole. Fig. 2 Orbital parameters of Main Belt Asteroids, color-coded according to ugriz colors measured by SDSS. The figure to the left shows osculating elements, the figure to the right shows proper elements - note the asteroid families visible as clumps in parameter space [1]. By obtaining multi-color ugrizy data for a substantial fraction of objects, relationships between color and dynamical history can be established. This will also enable taxonomic classification of asteroids, provide further links between diverse populations such as irregular satellites and TNOs or planetary Trojans, and enable estimates of asteroid diameter with rms uncertainty of 30%. With the addition of light-curve information, rotation periods and phase curves can be measured for large fractions of each population, leading to new insight on physical characteristics. Photometric variability information, together with sparse lightcurve inversion, will allow spin state and shape estimation for up to two orders of magnitude more objects than presently known. This will leverage physical studies of asteroids by constraining the size-strength relationship, which has important implications for the internal structure (solid, fractured, rubble pile) and in turn the collisional evolution of the asteroid belt. Similar information can be gained for other solar system bodies. [1] Parker, A., Ivezic

Guidance strategies and analysis for low thrust navigation

NASA Technical Reports Server (NTRS)

Jacobson, R. A.

1973-01-01

A low-thrust guidance algorithm suitable for operational use was formulated. A constrained linear feedback control law was obtained using a minimum terminal miss criterion and restricting control corrections to constant changes for specified time periods. Both fixed- and variable-time-of-arrival guidance were considered. The performance of the guidance law was evaluated by applying it to the approach phase of the 1980 rendezvous mission with the comet Encke.

Large Scale Morphological Changes in the Hapi Region on Comet 67P/Churyumov-Gerasimenko

NASA Astrophysics Data System (ADS)

Davidsson, B. J. R.; Lee, S.; Von Allmen, P. A. A.; Schloerb, F. P.; Hofstadter, M. D.; Sierks, H.; Barbieri, C.; Gulkis, S.; Keller, H. U.; Koschny, D.; Philippe, L.; Rickman, H.; Rodrigo, R.

2017-12-01

The Hapi region is located on the northern hemisphere of comet 67P/C-G at the neck that joins the twolobes of the nucleus. It primarily consists of granular material that is unresolved at 0.35 m/pixel resolutionand that forms a smooth surface with small slopes with respect to local gravity. The OSIRIS cameras on theESA spacecraft Rosetta observed Hapi regularly since its rendezvous with the comet in August 2014.No changes were seen during the first five months in orbit, but on December 30, 2014 two spots appeared in Hapi.Over the course of two months they grew gradually into a 110 by 70 meter shallow depression with a depth of about 0.5 meters.We use OSIRIS observations to characterize the morphology and spectrophotometry of the region. We usemeasurements of the thermal emission of the comet by the MIRO millimeter and submillimeter radiometer incombination with thermophysical modeling to characterize the surface temperature, near surface temperaturegradient, and thermal inertia of the region. The formation mechanism of the depression is discussed in view ofthese empirical data.

Large scale morphological changes in the Hapi region on comet 67P/Churyumov-Gerasimenko

NASA Astrophysics Data System (ADS)

Davidsson, Bjorn; Lee, Seungwon; von Allmen, Paul; Schloerb, Peter; Hofstadter, Mark; Sierks, Holger; Barbieri, Cesare; Gulkis, Samuel; Keller, Horst Uwe; Koschny, Detlef; Lamy, Philippe; Rickman, Hans; Rodrigo, Rafa; MIRO Team; OSIRIS Team

2017-10-01

The Hapi region is located on the northern hemisphere of comet 67P/C-G at the neck that joins the two lobes of the nucleus. It primarily consists of granular material that is unresolved at 0.35 m/pixel resolution and that forms a smooth surface with small slopes with respect to local gravity. The OSIRIS cameras on the ESA spacecraft Rosetta observed Hapi regularly since its rendezvous with the comet in August 2014. No changes were seen during the first five months in orbit but on December 30, 2014, two spots appeared in Hapi. Over the course of two months they grew gradually into a 110 by 70 meter shallow depression with a depth of about 0.5 meters. We use OSIRIS observations to characterize the morphology and spectrophotometry of the region. We use measurements of the thermal emission of the comet by the MIRO millimeter and submillimeter radiometer in combination with thermophysical modeling to characterize the surface temperature, near surface temperature gradient, and thermal inertia of the region. The formation mechanism of the depression is discussed in view of these empirical data.

Sixteenth Lunar and Planetary Science Conference. Press abstracts

NASA Technical Reports Server (NTRS)

1985-01-01

A broad range of topics concerned with lunar and planetary science are discussed. Topics among those included are, the sun, the planets, comets, meteorities, asteroids, satellites, space exploration, and the significance of these to Earth.

Disability Mentoring Day

NASA Image and Video Library

2011-04-07

A student from the Maryland School For the Blind explores an object while learning about Meteorites, Asteroids and Comets during NASA's Disability Mentoring Day, Thursday, April 7, 2011, at NASA Headquarters in Washignton. Photo Credit: (NASA/Paul E. Alers)

Disability Mentoring Day

NASA Image and Video Library

2011-04-07

A student from the Maryland School For the Blind asks a question while learning about Meteorites, Asteroids and Comets during NASA's Disability Mentoring Day, Thursday, April 7, 2011, at NASA Headquarters in Washignton. Photo Credit: (NASA/Paul E. Alers)

A-Track: Detecting Moving Objects in FITS images

NASA Astrophysics Data System (ADS)

Atay, T.; Kaplan, M.; Kilic, Y.; Karapinar, N.

2017-04-01

A-Track is a fast, open-source, cross-platform pipeline for detecting moving objects (asteroids and comets) in sequential telescope images in FITS format. The moving objects are detected using a modified line detection algorithm.

Impact on Comets and Asteroids

NASA Technical Reports Server (NTRS)

OKeefe, John D.; Stewart, Sarah T.; Ahrens, Thomas J.

2001-01-01

We characterized the impact physics in collisions on porous bodies by various density projectiles and defined different penetration modes (compression, spreading, or breakup) based on transitions between instability regimes. Additional information is contained in the original extended abstract.

Molecular Composition Analysis of Distant Targets

NASA Technical Reports Server (NTRS)

Hughes, Gary B.; Lubin, Philip

2017-01-01

This document is the Final Report for NASA Innovative Advanced Concepts (NIAC) Phase I Grant 15-NIAC16A-0145, titled Molecular Composition Analysis of Distant Targets. The research was focused on developing a system concept for probing the molecular composition of cold solar system targets, such as Asteroids, Comets, Planets and Moons from a distant vantage, for example from a spacecraft that is orbiting the target (Hughes et al., 2015). The orbiting spacecraft is equipped with a high-power laser, which is run by electricity from photovoltaic panels. The laser is directed at a spot on the target. Materials on the surface of the target are heated by the laser beam, and begin to melt and then evaporate, forming a plume of asteroid molecules in front of the heated spot. The heated spot glows, producing blackbody illumination that is visible from the spacecraft, via a path through the evaporated plume. As the blackbody radiation from the heated spot passes through the plume of evaporated material, molecules in the plume absorb radiation in a manner that is specific to the rotational and vibrational characteristics of the specific molecules. A spectrometer aboard the spacecraft is used to observe absorption lines in the blackbody signal. The pattern of absorption can be used to estimate the molecular composition of materials in the plume, which originated on the target. Focusing on a single spot produces a borehole, and shallow subsurface profiling of the targets bulk composition is possible. At the beginning of the Phase I research, the estimated Technology Readiness Level (TRL) of the system was TRL-1. During the Phase I research, an end-to-end theoretical model of the sensor system was developed from first principles. The model includes laser energy and optical propagation, target heating, melting and evaporation of target material, plume density, thermal radiation from the heated spot, molecular cross section of likely asteroid materials, and estimation of the absorption profile at a distant spectrometer. Results obtained by executing simulations based on the model provide compelling evidence that the concept of remote laser evaporative molecular absorption spectroscopy is feasible. In this document, technical details of the model are presented, and results of simulations are described that indicate the utility of the proposed sensor system. Additionally, an asteroid rendezvous mission is analyzed, with a survey of system requirements to accomplish molecular composition analysis of the asteroid. Based on positive theoretical results obtained during Phase I, the estimated TRL of the system is now TRL-2. This document also describes potential future research and experimentation that could push the system to TRL-4 within 2 years. Steps required for construction of a laboratory prototype are described. An experiment to test predictions of the theory is described, based on the laboratory prototype setup.

DARe: Dark Asteroid Rendezvous

NASA Technical Reports Server (NTRS)

Noll, K. S.; McFadden, L. A.; Rhoden, A. R.; Lim, L. F.; Boynton, W. V.; Carter, L. M.; Collins, G.; Englander, J. A.; Goossens, S. A.; Grundy, W. M.;

Tying Extinction Events to Comet Impacts Large Enough to Cause an Extinction in Themselves.

NASA Astrophysics Data System (ADS)

Burgener, J. A.

2017-12-01

Comets over 35 km in size impacting Earth will create vast fireballs, and will boil large parts of the oceans, causing extinction events in themselves. They will likely provide enough energy to shatter the crust and eject large masses of molten rock from the mantle, forming traps. Traps are clearly associated with extinction events, but are not expected to cause extinctions. While Chicxulub is recognized to have occurred at the time of the K/Pg boundary layer, it is recognized as being too small in itself to cause an extinction. Are large comet impacts likely? The Kuiper belt has more than 100,000 objects over 100 km in diameter and millions over 10 km. Typically their orbits are less stable than asteroid orbits due to large bodies such as Pluto moving through the belt. The asteroid belt has only 10,000 objects over 10 km diameter. Comet impacts should be more common than asteroid impacts, yet none of the recognized craters are expected to be due to comets. There are many features on Earth that are poorly explained by Plate Tectonics that would be well explained if they were considered to be comet impact craters. A consideration of the Black Sea and the Tarim Basin will show that impact interpretations are a better fit than the present Plate Tectonics' explanations. Both basins are in the midst of mountain building from plate collisions, but are themselves not being disturbed by the plate collisions. Both are ellipses angled at 23.4 degrees to the equator, matching the angle expected for a low angle impact from a comet traveling in the ecliptic. Both are too deep at 15 km depths to be standard oceans (typically 5 km deep). Both are filled with horizontal layers of sediments, undisturbed by the mountain building occurring at the edges. Both have thin crusts and high Moho boundaries. Both have thin lithosphere. Yet both show GPS movement of the land around them moving away from them, as though they were much thicker and stronger than the surrounding land. The Tarim Basin is 1000 km X 380 km, and the Black Sea is in two sections each 600 km X 350 km. They would require impactors in the range of 35 - 40 km diameter, hitting at impact angles of 20 - 30 degrees. The fireballs from such impacts would cover nearly half the planet, which would be large enough in themselves to cause extinctions.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kasuga, Toshihiro; Shirahata, Mai; Usui, Fumihiko

Most outer main-belt asteroids have low albedos because of their carbonaceouslike bodies. However, infrared satellite surveys have revealed that some asteroids have high albedos, which may suggest the presence of unusual surface minerals for those primitive objects. We present new near-infrared (1.1–2.5 μm) spectra of four outer main-belt asteroids with albedos ≥ 0.1. The C-complex asteroids (555) Norma and (2542) Calpurnia are featureless and have (50%–60%) amorphous Mg pyroxenes that might explain the high albedos. Asteroids (701) Oriola (which is a C-complex asteroid) and (2670) Chuvashia (a D/T-type or M-type asteroid) show possible broad absorption bands (1.5–2.1 μm). The featuremore » can be reproduced by either Mg-rich amorphous pyroxene (with 50%–60% and 80%–95% Mg, respectively) or orthopyroxene (crystalline silicate), which might be responsible for the high albedos. No absorption features of water ice (near 1.5 and 2.0 μm) are detected in the objects. We discuss the origin of high albedo components in the outer main-belt asteroids and their physical relations to comets.« less

The IRAS Minor Planet Survey

NASA Technical Reports Server (NTRS)

Tedesco, Edward F.; Veeder, Glenn J.; Fowler, John W.; Chillemi, Joseph R.

1992-01-01

This report documents the program and data used to identify known asteroids observed by the Infrared Astronomical Satellite (IRAS) and to compute albedos and diameters from their IRAS fluxes. It also presents listings of the results obtained. These results supplant those in the IRAS Asteroid and Comet Survey, 1986. The present version used new and improved asteroid orbital elements for 4679 numbered asteroids and 2632 additional asteroids for which at least two-opposition elements were available as of mid-1991. It employed asteroid absolute magnitudes on the International Astronomical Union system adopted in 1991. In addition, the code was modified to increase the reliability of associating asteroids with IRAS sources and rectify several shortcomings in the final data products released in 1986. Association reliability was improved by decreasing the position difference between an IRAS source and a predicted asteroid position required for an association. The shortcomings addressed included the problem of flux overestimation for low SNR sources and the systematic difference in albedos and diameters among the three wavelength bands (12, 25, and 60 micrometers). Several minor bugs in the original code were also corrected.

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.

Highest Resolution Topography of 433 Eros and Implications for MUSES-C

NASA Technical Reports Server (NTRS)

Cheng, A. F.; Barnouin-Jha, O.

2003-01-01

The highest resolution observations of surface morphology and topography at asteroid 433 Eros were obtained by the Near Earth Asteroid Rendezvous (NEAR) Shoemaker spacecraft on 12 February 2001, as it landed within a ponded deposit on Eros. Coordinated observations were obtained by the imager and the laser rangefinder, at best image resolution of 1 cm/pixel and best topographic resolution of 0.4 m. The NEAR landing datasets provide unique information on rock size and height distributions and regolith processes. Rocks and soil can be distinguished photometrically, suggesting that bare rock is indeed exposed. The NEAR landing data are the only data at sufficient resolution to be relevant to hazard assessment on future landed missions to asteroids, such as the MUSES-C mission which will land on asteroid 25143 (1998 SF36) in order to obtain samples. In a typical region just outside the pond where NEAR landed, the areal coverage by resolved positive topographic features is 18%. At least one topographic feature in the vicinity of the NEAR landing site would have been hazardous for a spacecraft.

Assessing the Main-Belt Comet Population with Comet Hunters

NASA Astrophysics Data System (ADS)

Schwamb, Megan E.; Hsieh, Henry H.; Zhang, Zhi-Wei; Chen, Ying-Tung; Lintott, Chris; Wang, Shiang-Yu; Mishra, Ishan

2017-01-01

Cometary activity in the asteroid belt is a recent discovery. Evidence suggests recent collisions play a role excavating subsurface water ice in these Main Belt Comets (MBCs). MBCs may be an alternative source of Earth’s water. The properties and origins of the MBCs remain elusive. To date ~15 MBCs are known, but only with many tens to 100s of MBCs can we fully explore this new reservoir and its implications for the early Earth.Automated routines identify cometary objects by comparing the point spread functions (PSFs) of moving objects to background stars. This approach may miss cometary activity with low-level dust comae or trails that are too weak or extended to affect an object's near-nucleus PSF profile. Direct visual inspection of moving objects by survey team members can often catch such unusual objects, but such an approach is impractical for the largest surveys to date, and will only become more intractable with the next generation wide-field surveys.With the Internet, tens of thousands of people can be engaged in the scientific process. With this citizen science approach, the combined assessment of many non-experts often equals or rivals that of a trained expert and in many cases outperforms automated algorithms. The Comet Hunters (http://www.comethunters.org) project enlists the public to search for MBCs in data from the Hyper Suprime-Cam (HSC) wide survey. HSC is to date the largest field-of-view camera (covering a 1.5 degree diameter circle on sky) on a 8-10-m class telescope. The HSC wide survey provides the sensitivity to detect cometary activity at lower levels than have been possible for previous surveys.We will give an overview of the Comet Hunters project. We will present the results from the first ~10,000 HSC asteroids searched and provide an estimate on the frequency of cometary activity in the Main Asteroid beltAcknowledgements: This work uses data generated via the Zooniverse.org platform, development of which was supported by a Global Impact Award from Google, and by the Alfred P. Sloan Foundation. The HSC collaboration includes the astronomical communities of Japan and Taiwan, and Princeton University.

The cometary and asteroidal impactor flux at the earth

NASA Technical Reports Server (NTRS)

Weissman, Paul R.

1988-01-01

The cratering records on the Earth and the lunar maria provide upper limits on the total impactor flux at the Earth's orbit over the past 600 Myr and the past 3.3 Gyr, respectively. These limits can be compared with estimates of the expected cratering rate from observed comets and asteroids in Earth-crossing orbits, corrected for observational selection effects and incompleteness, and including expected temporal variations in the impactor flux. Both estimates can also be used to calculate the probability of large impacts which may result in biological extinction events on the Earth. The estimated cratering rate on the Earth for craters greater than 10 km-diameter, based on counted craters on dated surfaces is 2.2 + or - 1.1 x 10 to the minus 14th power km(-2) yr(-1) (Shoemaker et al., 1979). Using a revised mass distribution for cometary nuclei based on the results of the spacecraft flybys of Comet Halley in 1986, and other refinements in the estimate of the cometary flux in the terrestrial planets zone, it is now estimated that long-period comets account for 11 percent of the cratering on the Earth (scaled to the estimate above), and short-period comets account for 4 pct (Weissman, 1987). However, the greatest contribution is from large but infrequent, random cometary showers, accounting for 22 pct of the terrestrial cratering.

Organic matter in meteorites and comets - Possible origins

NASA Technical Reports Server (NTRS)

Anders, Edward

1991-01-01

At least six extraterrestrial environments may have contributed organic compounds to meteorites and comets: solar nebula, giant-planet subnebulae, asteroid interiors containing liquid water, carbon star atmospheres, and diffuse or dark interstellar clouds. The record in meteorites is partly obscured by pervasive reheating that transformed much of the organic matter to kerogen; nonetheless, it seems that all six formation sites contributed. For comets, the large abundance of HCHO, HCN, and unsaturated hydrocarbons suggests an interstellar component of 50 percent or more, but the contributions of various interstellar processes, and of a solar-nebula component, are hard to quantify. A research program is outlined that may help reduce these uncertainties.

DEEP-South: Preliminary Photometric Results from the KMTNet-CTIO

NASA Astrophysics Data System (ADS)

Kim, Myung-Jin; Moon, Hong-Kyu; Choi, Young-Jun; Yim, Hong-Suh; Bae, Young-Ho; Roh, Dong-Goo; Park, Jin Tae; Moon, Bora

2016-01-01

Korea Astronomy and Space Science Institute (KASI) successfully completed the development of Korea Microlensing Telescope Network (KMTNet, Park et al. 2012) in mid-2015, following which it conducted test runs for several months. `DEep Ecliptic Patrol of the Southern sky' (DEEP-South, Moon et al. 2015), which will be used for asteroid and comet studies, will not only characterize targeted asteroids, carrying out blind surveys toward the sweet spots, but will also mine the data of such bodies using the KMTNet archive. We report preliminary lightcurves of four Potentially Hazardous Asteroids (PHAs) from test runs at KMTNet-CTIO in the February - May 2015 period.

Comet nuclear magnitudes and a new size distribution using archived NEAT data.

NASA Astrophysics Data System (ADS)

Bambery, R. J.; Hicks, M. D.; Pravdo, S. H.; Helin, E. F.; Lawrence, K. J.

2002-09-01

A reliable estimate of the size distribution of cometary nuclei provides important constraints on the formation and dynamical/physical evolution of these bodies as well as their relative proportions in the near-Earth population. The basic data of nuclear sizes has been difficult to obtain, due to the shroud of dust that envelopes the nucleus across a wide range of heliocentric distances. Only two comets, P/Halley and P/Borrelly, have had direct imaging of their nuclei from spacecraft encounters, though high spatial-resolution imaging by the Hubble Space Telescope has also yielded very reliable diameters [1]. Other observers have recently used ground-based photometry to obtain cumulative size-frequency distributions which are not in agreement [2,3]. One possible source of error is the need to include data from a wide range of telescopes and reduction techniques. We shall obtain a new estimate of the size-frequency distribution using a self-consistent data-set. The Near-Earth Asteroid Tracking (NEAT) Program at the Jet Propulsion laboratory remotely operates two 1.2-meter telescopes at widely geographically separated locations on a near-nightly basis. All NEAT data is archived and publically available through the SKYMORPH website (http:/skyview.gsfc.nasa.gov/skymorph/skymorph.html) Though optimized to discover near-Earth asteroids, we have obtained over 300 CCD images of approximately 40 short and long-period comets over the last 15 months. Though we model coma contamination for all images, we shall concentrate on the fraction of comets at heliocentric distances greater than 3 AU. Our data will be used to derive an independent comet size-frequency distribution .

Oxygen isotope reservoirs in the outer asteroid belt inferred from oxygen isotope systematics of chondrule olivines and isolated forsterite and olivine grains in Tagish Lake-type carbonaceous chondrites, WIS 91600 and MET 00432

NASA Astrophysics Data System (ADS)

Yamanobe, Masakuni; Nakamura, Tomoki; Nakashima, Daisuke

2018-03-01

To understand oxygen isotope ratios and redox conditions of the chondrule formation environments of the outer rigions of the asteroid belt, we analyzed major element concentrations and oxygen isotope ratios of olivine grains in chondrules, isolated forsterite, and isolated olivine from the WIS 91600 and MET 00432 carbonaceous chondrites, which are thought to have originated from D-type asteroids located in the outer asteroid belt. The oxygen isotope ratios of individual chondrules and isolated grains show a wide variation in δ18O from -9.9‰ to +9.1‰ along the carbonaceous chondrite anhydrous mineral (CCAM) and primitive chondrule mineral (PCM) lines. The Δ17O (= δ17O - 0.52 × δ18O) values of the measured objects increase with decreasing Mg#; i.e., FeO-poor objects (Mg# > 90; type I chondrules and isolated forsterites) mainly have Δ17O values of ca. -6‰, and FeO-rich objects (Mg# < 90; type II chondrules and isolated olivines) have Δ17O values ranging from -3‰ to +2‰. Similar trends are observed for ferromagnesian silicate particles from comet Wild2 and CR chondrite chondrules, particularly in terms of FeO-rich objects with Δ17O values ranging from -3‰ to +2‰. It is suggested that FeO-rich objects formed in the outer regions of the asteroid belt and were transported to the outer solar nebular regions where comet Wild2 formed.

Remote comets and related bodies - VJHK colorimetry and surface materials

NASA Technical Reports Server (NTRS)

Hartmann, W. K.; Cruikshank, D. P.; Degewij, J.

1982-01-01

VJHK colors for a number of asteroids and eight comets at various solar distances and levels of activity were obtained, and the observations are interpreted in terms of a two-component mixing model in which outer solar system interplanetary bodies are viewed as mixtures of ice and dark carbonaceous-type (RD and C) dirt. It is inferred that the observed comets have comae, and perhaps surfaces, of dirty ice or ice dirt grains colored by an RD-dirt component. This inference is supported by systematics of an 'alpha index' based on VJHK colors and empirically correlated with albedo and ice/dirt ratio. Among comets the alpha index correlates with solar distance in a way that suggests comets emit dirty ice grains which are stable at large solar distance but from which the ice component sublimes and leaves dirt grains at small solar distance.

The volatile composition of comets

NASA Technical Reports Server (NTRS)

Weaver, H. A.

1988-01-01

Comets may be our best probes of the physical and chemical conditions in the outer regions of the solar nebula during that crucial period when the planets formed. The volatile composition of cometary nuclei can be used to decide whether comets are the product of a condensation sequence similar to that invoked to explain the compositions of the planets and asteroids, or if comets are simply agglomerations of interstellar grains which have been insignificantly modified by the events that shaped the other bodies in the solar system. Although cometary nuclei are not generally accessible to observation, observations of cometary comae can illuminate at least some of the mysteries of the nuclei provided one has a detailed knowledge of the excitation conditions in the coma and also has access to basic atomic and molecular data on the many species present in comets. Examined here is the status of our knowledge of the volatile composition of cometary nuclei and how these data are obtained.

Asteroids Search Results in Large Photographic Sky Surveys

NASA Astrophysics Data System (ADS)

Shatokhina, S. V.; Kazantseva, L. V.; Yizhakevych, O. M.; Eglitis, I.; Andruk, V. M.

Photographic observations of XX century contained numerous and varied information about all objects and events of the Universe fixed on plates. The original and interesting observations of small bodies of the Solar system in previous years can be selected and used for various scientific tasks. Existing databases and online services can help make such selection easily and quickly. The observations of chronologically earlier ppositions, photometric evaluation of brightness for long periods of time allow refining the orbits of asteroids and identifying various non-stationaries. Photographic observations of Northern Sky Survey project and observations of clusters in UBVR bands were used for global search for small bodies of Solar system. Total we founded 2486 positions of asteroids and 13 positions of comets. All positions were compared with ephemeris. It was found that 80 positions of asteroids have a moment of observation preceding their discovery, and 19 of them are chronologically the earliest observations of these asteroids in the world.

A Comprehensive Model of the Meteoroids Environment Around Mercury

NASA Astrophysics Data System (ADS)

Pokorny, P.; Sarantos, M.; Janches, D.

2018-05-01

We present a comprehensive dynamical model for the meteoroid environment around Mercury comprised of meteoroids originating in asteroids, short and long period comets. Our model is fully calibrated and provides predictions for different values of TAA.

Space Radar of Image Aorounga Impact Crater, Chad

NASA Image and Video Library

1999-04-15

The impact of an asteroid or comet several hundred million years ago left scars in the landscape that are still visible in this spaceborne radar image of an area in the Sahara Desert of northern Chad.

Space Radar Image of Possible String of Impact Creaters

NASA Image and Video Library

1999-04-15

The impact of an asteroid or comet several hundred million years ago left scars in the landscape that are still visible in this spaceborne radar image of an area in the Sahara Desert of northern Chad.

Disability Mentoring Day

NASA Image and Video Library

2011-04-07

A student from the Maryland School For the Blind touches a piece of moon rock while learning about Meteorites, Asteroids and Comets during NASA's Disability Mentoring Day, Thursday, April 7, 2011, at NASA Headquarters in Washignton. Photo Credit: (NASA/Paul E. Alers)

Anchoring Technology for In Situ Exploration of Small Bodie

NASA Technical Reports Server (NTRS)

Steltzner, A.; Nasif, A.

2000-01-01

Comets, asteroids and other small bodies found in the solar system do not possess enough gravity to ensure spacecraft contact forces sufficient to allow many types of in situ science, such as core or surface sampling.

Meteor showers associated with 2003EH1

NASA Astrophysics Data System (ADS)

Babadzhanov, P. B.; Williams, I. P.; Kokhirova, G. I.

2008-06-01

Using the Everhart RADAU19 numerical integration method, the orbital evolution of the near-Earth asteroid 2003EH1 is investigated. This asteroid belongs to the Amor group and is moving on a comet-like orbit. The integrations are performed over one cycle of variation of the perihelion argument ω. Over such a cycle, the orbit intersect that of the Earth at eight different values of ω. The orbital parameters are different at each of these intersections and so a meteoroid stream surrounding such an orbit can produce eight different meteor showers, one at each crossing. The geocentric radiants and velocities of the eight theoretical meteor showers associated with these crossing points are determined. Using published data, observed meteor showers are identified with each of the theoretically predicted showers. The character of the orbit and the existence of observed meteor showers associated with 2003EH1 confirm the supposition that this object is an extinct comet.

Galileo Avionica's technologies and instruments for planetary exploration.

PubMed

Battistelli, E; Falciani, P; Magnani, P; Midollini, B; Preti, G; Re, E

2006-12-01

Several missions for planetary exploration, including comets and asteroids, are ongoing or planned by the European Space Agencies: Rosetta, Venus Express, Bepi Colombo, Dawn, Aurora and all Mars Programme (in its past and next missions) are good examples. The satisfaction of the scientific request for the mentioned programmes calls for the development of new instruments and facilities devoted to investigate the body (planet, asteroid or comet) both remotely and by in situ measurements. The paper is an overview of some instruments for remote sensing and in situ planetary exploration already developed or under study by Galileo Avionica Space & Electro-Optics B.U. (in the following shortened as Galileo Avionica) for both the Italian Space Agency (ASI) and for the European Space Agency (ESA). Main technologies and specifications are outlined; for more detailed information please refer to Galileo Avionica's web-site at: http://www.galileoavionica.com .

Impact of Utilizing Photos and Deimos as Waypoints for Mars Human Surface Missions

NASA Technical Reports Server (NTRS)

Cianciolo, Alicia D.; Brown, Kendall

2015-01-01

Phobos and Deimos, the moons of Mars, are interesting exploration destinations that offer extensibility of the Asteroid Redirect Mission (ARM) technologies. Solar Electric Propulsion (SEP), asteroid rendezvous and docking, and surface operations can be used to land on and explore the moons of Mars. The close Mars vicinity of Phobos and Deimos warrant examining them as waypoints, or intermediate staging orbits, for Mars surface missions. This paper outlines the analysis performed to determine the mass impact of using the moons of Mars both as an intermediate staging point for exploration as well as for in-situ recourse utilization, namely propellant, to determine if the moons are viable options to include in the broader Mars surface exploration architecture.

Rosetta following a living comet

NASA Astrophysics Data System (ADS)

Accomazzo, Andrea; Ferri, Paolo; Lodiot, Sylvain; Pellon-Bailon, Jose-Luis; Hubault, Armelle; Porta, Roberto; Urbanek, Jakub; Kay, Ritchie; Eiblmaier, Matthias; Francisco, Tiago

2016-09-01

The International Rosetta Mission was launched on 2nd March 2004 on its 10 year journey to rendezvous with comet 67P Churyumov-Gerasimenko. Rosetta performed comet orbit insertion on the 6th of August 2014, after which it characterised the nucleus and orbited it at altitudes as low as a few kilometres. In November 2014 Rosetta delivered the lander Philae to perform the first soft landing ever on the surface of a comet. The critical landing operations have been conducted with remarkable accuracy and will constitute one of the most important achievements in the history of spaceflight. After this critical operation, Rosetta began the escort phase of the comet in its journey in the Solar System heading to the perihelion, reached in August 2015. Throughout this period, the comet environment kept changing with increasing gas and dust emissions. A first phase of bound orbits was followed by a sequence of complex flyby segments which allowed the scientific instruments to perform in depth investigation of the comet environment and nucleus. The unpredictable nature of the comet activity forced the mission control team to implement unplanned changes to the flight plan prepared for this mission phase and to plan the whole mission in a more dynamic way than originally conceived. This paper describes the details of the landing operations and of the main comet escort phase. It also includes the mission status as achieved after perihelion and the findings about the evolution of the comet and its environment from a mission operations point of view. The lessons learned from this unique and complex operations phase and the plans for the next mission phases, which include a mission extension into 2016, are also described.

Sources of cosmic dust in the Earth's atmosphere

NASA Astrophysics Data System (ADS)

Carrillo-Sánchez, J. D.; Nesvorný, D.; Pokorný, P.; Janches, D.; Plane, J. M. C.

2016-12-01

There are four known sources of dust in the inner solar system: Jupiter Family comets, asteroids, Halley Type comets, and Oort Cloud comets. Here we combine the mass, velocity, and radiant distributions of these cosmic dust populations from an astronomical model with a chemical ablation model to estimate the injection rates of Na and Fe into the Earth's upper atmosphere, as well as the flux of cosmic spherules to the surface. Comparing these parameters to lidar observations of the vertical Na and Fe fluxes above 87.5 km, and the measured cosmic spherule accretion rate at South Pole, shows that Jupiter Family Comets contribute (80 ± 17)% of the total input mass (43 ± 14 t d-1), in good accord with Cosmic Background Explorer and Planck observations of the zodiacal cloud.

Hst Measurements Of Main Belt Comet 300163

NASA Astrophysics Data System (ADS)

Jewitt, David; Weaver, H.; Agarwal, J.; Mutchler, M.; Larson, S.

2012-10-01

Asteroid 300163 (semimajor axis 3.05 AU, eccentricity 0.20, inclination 3 deg., Tisserand parameter 3.20) is a source of dust, giving it the dual cometary designation P/2006 VW139. It satisfies the definition of a main-belt comet (MBC) by having the orbital character of a main-belt asteroid but the diffuse appearance of a comet. We obtained Hubble Space Telescope observations of this object in December 2011 in order to study the morphology of the ejected dust at the highest angular resolution and to determine the cause of the mass loss from the nucleus. One of the two HST observing epochs was carefully timed to coincide with the Earth's crossing of the orbital plane (out of plane angle 0.01 deg.) to obtain a measure of the vertical velocity dispersion free from the effects of projection. We find an extraordinarily thin dust sheet and infer a sub-meter per second dust ejection velocity. Observations at the second epoch show a change in the near-nucleus dust morphology that indicates continuing ejection (i.e. the dust emission is not impulsive). We use the low velocity ejection, coupled with the absence of an observable coma, to help constrain the possible source mechanisms for the dust.