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Morphology and compositional differentiation of the surface of comets
The spacecraft missions to Comet Halley gave us the first detailed view of a comet nucleus. What was suspected before, that the nucleus surface was heterogeneous, was confirmed. The Halley Multicolor Camera aboard Giotto recorded jet-like dust features emanating from active regions covering approximately 15 percent of the surface that were responsible for emitting most of the dust and gas. An intensity gradient across the nucleus originating at the active areas and falling off to the darker, inactive region on the night side is caused by small particles that are more easily entrained by surface winds than larger particles that tend to remain in the jets. Data from the PIA (Giotto) and PUMA (Vega 1,2) instruments indicate that the smallest dust particles are enriched with organics (CHON particles). Some of this fine dust gravitationally settles creating a thin surface layer rich in organics. Particularly strong dust jets may cause wind-blown surface structures over inactive areas, such as, leeward dust accumulation behind hills. At close heliocentric distances the fine dust may be sintered on the surface.
Physical properties of Jupiter-family comets and spacecraft mission targets
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Halley's Comet flythrough and rendezvous missions via solar electric propulsion
Characteristics and capabilites of solar electric propulsion for missions to Halleys comet due to return 1985-1986
Terminal navigation analysis for the 1980 comet Encke slow flyby mission
The initial results of a terminal navigation analysis for the proposed 1980 solar electric slow flyby mission to the comet Encke are presented. The navigation technique employs onboard optical measurements with the scientific television camera, groundbased observations of the spacecraft and comet, and groundbased orbit determination and thrust vector update computation. The knowledge and delivery accuracies of the spacecraft are evaluated as a function of the important parameters affecting the terminal navigation. These include optical measurement accuracy, thruster noise level, duration of the planned terminal coast period, comet ephemeris uncertainty, guidance initiation time, guidance update frequency, and optical data rate.
Comet Nucleus Tour (CONTOUR) A Mission to Study the Diversity of Comet Nuclei
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Contour: The Comet Nucleus Tour Mission
Target Selection: emphasis on diversity and unique objects. Flybys of three comets.
A Post-Stardust Mission View of Jupiter Family Comets
Before the Stardust Mission, many persons (including the mission team) believed that comet nuclei would be geologically boring objects. Most believed that comet nucleus mineralogy would be close or identical to the chondritic interplanetary dust particles (IDPs), or perhaps contain mainly amorphous nebular condensates or that comets might even be composed mainly of preserved presolar material [1]. Amazingly, the results for Comet Wild 2 (a Jupiter class comet) were entirely different. Whether this particular comet will ultimately be shown to be typical or atypical will not be known for a rather long time, so we describe our new view of comets from the rather limited perspective of this single mission.
Trajectory and guidance analysis. comet and close-approach asteroid mission study, volume 3 final report, 2 jul. 1964 - 2 jan. 1965
Trajectory and guidance analysis for flyby mission to comet and close-approach asteroid
The Deep Space 4/Champollion Comet Rendezvous and Lander Technology Demonstration Mission
The Deep Space 4/Champollion mission is designed to test and validate technologies for landing on and anchoring to small bodies, and sample collection and transfer, in preparation for future sample return missions from comets, asteriods, and satellites.
Arecibo Observatory support of the US international cometary Explorer mission encounter at comet Giacobini-Zinner
The Arecibo Observatory in Puerto Rico participated in the support of the U.S. International Cometary Explorer (ICE) mission when the ICE spacecraft passed through the tail of comet Giacobini-Zinner on September 11, 1985. The Arecibo Observatory is a research facility of the National Astronomy and Ionosphere Center (NAIC) operated by Cornell University under contract to the National Science Foundation (NSF). Coverage of the encounter involved the use of the observatory's 305-m (1000-ft) radio reflector antenna and RF and data system equipment fabricated or modified specifically for support of the ICE mission. The successful implementation, testing, and operation of this temporary receive, record, and data relay capability resulted from a cooperative effort by personnel at the Arecibo Observatory, the Goddard Space Flight Center, and the Jet Propulsion Laboratory.
COMET Progresses Toward First Mission
The COMmercial Experiment Transporter (COMET) is a set of hardware and related infrastructure used to support orbital experiments of the CDD's and their industrial partners. During this year major support contracts were signed, preliminary design reviews conducted, experiments selected for the first mission, and long lead items place on order. The Program Office and CCDS Monitors took an active role in guiding COMET through the activation maze. Launch and recovery sites were selected and licenses for the launch vehicle, recovery system, and recovery operations were filed by the contractors with the Department of Transportation. As the period closed, COMET was preparing for Critical Design Reviews on all major systems and a target launch data was selected. This report deals primarily with the programmatic issues which were resolved as the program matured. At times is is impossible to disassociate the technical from the programmatic and, in such cases the technical material is presented to provide insight into the paths selected by both CCDS and Contractor Management.
A proposed comet nucleus penetrator for the Comet Rendezvous Asteroid Flyby mission
The importance of the study of comets has led NASA to plan a mission to rendezvous with comet Tempel 2 in 1997. Critical to the understanding of comets will be measurements of the nucleus material to determine its elemental and isotopic composition, its mechanical properties, and its thermal state and properties. this paper describes a proposal for a Comet Nucleus Penetrator to accomplish these measurement goals. The Comet Nucleus Penetrator will implant instruments into the comet's nucleus beneath a probable volatile-depleted surface mantle into material more representative of the bulk composition of the nucleus.
The Deep Space 4/Champollion Comet Rendezvous and Lander Technology Demonstration Mission
The Deep Space 4/Champollion mission is designed to test and validate technologies for landing on and anchoring to small bodies, and sample collection and transfer, in preparation for future sample return missions from comets, asteroids, and satellites. in addition, DS-4 will test technologies for advanced, multi-engine solar electric propulsion (SEP) systems, inflatable-rigidizable solar arrays, autonomous navigation and precision guidance for landing, autonomous hazard detection and avoidance, and advanced integrated avionics and packaging concepts. Deep Space-4/Champollion consists of two spacecraft: an orbiter/carrier vehicle which includes the multi-engine SEP stage, and a lander, called Champollion, which will descend to the surface of the 46P/Tempel 1 cometary nucleus. The spacecraft will launch in April, 2003 and land on the comet in September, 2006 Deep Space 4/Champollion is a joint project between NASA and CNES, the French space agency.
Comet and close approach asteroid mission study final report
Comet and close approach asteroid missions
Interplanetary trajectory design for the Mariner Mark II Comet Rendezvous/Asteroid Flyby mission
The primary purpose of the first mission utilizing a Mariner Mark II spacecraft will be to rendezvous with the short-period comet Wild 2 and conduct a proximal examination during the comet's quiescent and active phases. The purpose of the present study is to elucidate, using an accurate dynamic model, some of the characteristics of the interplanetary trajectory that are relevant to the mission design. Optimal transfer trajectories are generated, constrained by the Shuttle/Centaur launch vehicle capability and the total spacecraft mass and performance. Asteroid flyby opportunities are examined, and the effects of selected asteroid encounters on mission performance are discussed.
Analysis of the Touch-And-Go Surface Sampling Concept for Comet Sample Return Missions
This paper studies the Touch-and-Go (TAG) concept for enabling a spacecraft to take a sample from the surface of a small primitive body, such as an asteroid or comet. The idea behind the TAG concept is to let the spacecraft descend to the surface, make contact with the surface for several seconds, and then ascend to a safe location. Sampling would be accomplished by an end-effector that is active during the few seconds of surface contact. The TAG event is one of the most critical events in a primitive body sample-return mission. The purpose of this study is to evaluate the dynamic behavior of a representative spacecraft during the TAG event, i.e., immediately prior, during, and after surface contact of the sampler. The study evaluates the sample-collection performance of the proposed sampling end-effector, in this case a brushwheel sampler, while acquiring material from the surface during the contact. A main result of the study is a guidance and control (G&C) validation of the overall TAG concept, in addition to specific contributions to demonstrating the effectiveness of using nonlinear clutch mechanisms in the sampling arm joints, and increasing the length of the sampling arms to improve robustness.
Ephemeris data and error analysis in support of a Comet Encke intercept mission
Utilizing an orbit determination based upon 65 observations over the 1961 - 1973 interval, ephemeris data were generated for the 1976-77, 1980-81 and 1983-84 apparitions of short period comet Encke. For the 1980-81 apparition, results from a statistical error analysis are outlined. All ephemeris and error analysis computations include the effects of planetary perturbations as well as the nongravitational accelerations introduced by the outgassing cometary nucleus. In 1980, excellent observing conditions and a close approach of comet Encke to the earth permit relatively small uncertainties in the cometary position errors and provide an excellent opportunity for a close flyby of a physically interesting comet.