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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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NASA NTRS1992

Mission options for rendezvous with the most accessible Near-Earth Asteroid - 1989 ML

The recent discovery of the Amor-class 1989 ML, the most accessible known asteroid for minimum-energy rendezvous missions, has expedited the search for frequent, low-cost Near-Earth Asteroid rendezvous and round-trip missions. This paper identifies trajectory characteristics and assesses mass performance for low Delta V ballistic rendezvous opportunities to 1989 ML during the period 1996-2010. This asteroid also offers occasional unique extended mission opportunities, such as the lowest known Delta V requirement for any asteroid sample return mission as well as pre-rendezvous asteroid flyby and post-rendezvous comet flyby opportunities requiring less than 5.25 km/sec total Delta V. This paper also briefly comments concerning mission opportunities for asteroid 1991 JW, which recently replaced other known asteroids as the most accessible Near-Earth Asteroid for fast rendezvous and round-trip missions.

Mcadams, Jim V.↗
NASA NTRS1991

The comet rendezvous asteroid flyby mission: A status report

The Comet Rendezvous Asteroid Flyby (CRAF) mission received a new start in fiscal year 1990. CRAF will match orbits with an active short-period comet and follow it around the Sun, making scientific measurements of the nucleus, coma, and tail. The Imaging system will map the nucleus surface at a resolution of 1 meter/line-pair or better, while Visible and Infrared Mapping Spectrometer (VIMS) and Thermal Infrared Radiometer Experiment (TIREX) will produce spectral and thermal maps of the surface. Onboard instruments will collect cometary dust, ice, and gases and perform elemental and molecular analysis. A suite of fields and particles instruments will observe the solar wind interaction with the cometary atmosphere and tail. Radio tracking of the spacecraft will provide an accurate measure of the nucleus mass and higher harmonics in the comet's gravity field. En route to the comet, the spacecraft will make a close flyby of a large asteroid, preferably a primitive type from the outer main belt. Observations at the asteroid include remote sensing mapping of the surface, detection of any solar wind interaction observable at the flyby distance, and measurement of the asteroid mass to better than 10 percent accuracy. Detailed design of the CRAF spacecraft is currently underway at the Jet Propulsion Laboratory (JPL). Recent mass growth has necessitated a switch to Venus-Earth gravity assist type trajectories, similar to that used by the Galileo spacecraft. These trajectories require longer flight times from launch to rendezvous with the target comet. The details of the current baseline mission, spacecraft design, and instrument payload will be reviewed.

Weissman, Paul R.↗
NASA NTRS1989

Thermal design for the Comet Rendezvous Asteroid Flyby spacecraft

The mission overview of the Comet Rendezvous Asteroid Flyby (CRAF) spacecraft, which is planned to rendezvous with Comet Kopff in 1998, is presented, together with the CRAF mission trajectory. The preliminary thermal design of the CRAF spacecraft is discussed, with emphasis placed on the Low Precision Pointing Platform, Bus, Propulsion Module, and Comet Penetrator, the thermal design of which was impacted most by the comet environment. Model simulations showed the design of the bus and the propulsion module subsystems to be adequate. Configuration diagrams are included.

Tsuyuki, G. T.↗
NASA NTRS1988

Trajectory design for the Comet Rendezvous Asteroid Flyby 1995-1996 opportunities

Recent reprogramming of NASA's Comet Rendezvous Asteroid Flyby (CRAF) mission has motivated an examination of the comet rendezvous opportunities available with launch dates in 1995 and 1996. Various interplanetary transfer modes have been investigated including direct, Delta V-earth-gravity- assist and Venus/earth gravity assist trajectories. Optimal trajectories have been generated and their performance assessed for a spacecraft using a chemical propulsion system and the upgraded Titan/Centaur launch vehicle. Of the viable options available, a new CRAF baseline mission has been selected. One important result of the present study is that while there are comet rendezvous trajectories with launch dates throughout the next decade, 1997 marks the beginning of a hiatus of opportunities with short flight times to the comet targets which promise the greatest potential science return.

Myers, Mark R.↗
NASA NTRS1987

The Comet Rendezvous Asteroid Flyby project

The first Mariner Mark II (MMII) mission, the Comet Rendezvous Asteroid Flyby (CRAF), is described in detail. The comet Tempe 2 has been selected as the rendezvous target. The CRAF payload will include a cometary retarding ion mass spectrometer, a cometary ice and dust experiment, a penetrator/lander, a thermal IR radiometer, and a visual IR mapping spectrometer.

Draper, Ronald F.↗
NASA NTRS1973

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.

Jacobson, R. A.↗
NASA NTRS1992

Interplanetary mission design for the Comet Rendezvous Asteroid Flyby mission

As part of the CRAF/Cassini Project, the Comet Rendezvous Asteroid Flyby (CRAF) mission will explore primitive solar system bodies. CRAF is unique in that there are a number of scientifically acceptable targets from which to choose. In principle, each may be reached with several types of trajectories. This results in a large number of potential mission opportunities which must be considered. The various mission modes being considered will be discussed along with the criteria by which these missions are evaluated in order to reduce them to a smaller set. Also, the current primary and backup missions will be discussed.

Williams, S. N.↗
NASA NTRS1991

Short-period comets

The spacecraft flybys of Comet Halley in 1986 confirmed Whipple's icy conglomerate hypothesis for cometary nuclei and showed that comets are far richer in volatiles than any other class of solar system bodies. Water is the most abundant volatile, comprising roughly 80 percent of the gas flowing out from the nucleus. Carbon monoxide is next with a content of 15 percent relative to water, though with approximately half of that coming from an extended source in the cometary coma, i.e., hydrocarbon dust grains. The detection of large numbers of hydrocarbon CHON grains was one of the more significant discoveries of the Halley flybys, as was the ground-based observation that CN occurs in jets, again indicating an extended source. Evidence was also found for more complex hydrocarbons. Estimates of the total dust-to-gas ratio for Halley range as high as 2:1, indicating that a substantial fraction of the volatile material may be tied up in solid hydrocarbons rather than ices. The role of clathrates in trapping more volatile ices is not yet understood. If Halley can be taken to be representative of all short-period comets, then the short-period comets may provide a significant source of volatiles in near-earth space. This resource is more difficult to reach dynamically than the near-earth asteriods, but the high volatile content may justify the additional effort necessary. In addition, there is considerable evidence that at least some fraction of the near-earth asteriods are extinct cometary nuclei which have evolved into asteroid orbits, and which may contain significant volatiles buried beneath an insulating lag-deposit crust of nonvolatiles. Knowledge of comets will be greatly enhanced in the near future by the Comet Rendezvous Flyby mission now under development by NASA, and by the proposed Rosetta mission.

Weissman, Paul R.↗
NASA NTRS2000

Stardust Navigation Covariance Analysis

The Stardust spacecraft was launched on February 7, 1999 aboard a Boeing Delta-II rocket. Mission participants include the National Aeronautics and Space Administration (NASA), the Jet Propulsion Laboratory (JPL), Lockheed Martin Astronautics (LMA) and the University of Washington. The primary objective of the mission is to collect in-situ samples of the coma of comet Wild-2 and return those samples to the Earth for analysis. Mission design and operational navigation for Stardust is performed by the Jet Propulsion Laboratory (JPL). This paper will describe the extensive JPL effort in support of the Stardust pre-launch analysis of the orbit determination component of the mission covariance study. A description of the mission and it's trajectory will be provided first, followed by a discussion of the covariance procedure and models. Predicted accuracy's will be examined as they relate to navigation delivery requirements for specific critical events during the mission. Stardust was launched into a heliocentric trajectory in early 1999. It will perform an Earth Gravity Assist (EGA) on January 15, 2001 to acquire an orbit for the eventual rendezvous with comet Wild-2. The spacecraft will fly through the coma (atmosphere) on the dayside of Wild-2 on January 2, 2004. At that time samples will be obtained using an aerogel collector. After the comet encounter Stardust will return to Earth when the Sample Return Capsule (SRC) will separate and land at the Utah Test Site (UTTR) on January 15, 2006. The spacecraft will however be deflected off into a heliocentric orbit. The mission is divided into three phases for the covariance analysis. They are 1) Launch to EGA, 2) EGA to Wild-2 encounter and 3) Wild-2 encounter to Earth reentry. Orbit determination assumptions for each phase are provided. These include estimated and consider parameters and their associated a-priori uncertainties. Major perturbations to the trajectory include 19 deterministic and statistical maneuvers planned for the mission. The spacecraft is three axis stabilized and has unbalanced thrusters for attitude control. Accelerations due to the attitude control system are treated stochastically. The tracking scenario for the study is patterned after the actual schedule employed during the different phases of the mission. Conventional X-band two-way Doppler and SRA range data was simulated and the standard accuracy for these data types was assumed throughout most of the mission. However, a deweighting scheme was used for the Doppler data during times of low Sun-Earth-Probe angles, especially in the case of the DSM. Optical data is assumed to be available starting at 50 days prior to the comet encounter. The optical data will be used to improve the ephemeris of Wild-2, which is considered crucial to properly target the comet flyby. Results of the covariance analysis are presented for all mission phases. Navigation capability will be discussed in terms of the uncertainty in the encounter B-Plane (B.R and B.T) and linearized time of flight. Delivery errors based on the final maneuver prior to the comet encounter will be presented. The most stringent navigation requirement is for the Earth reentry. The uncertainty in the flight path angle must be less than 0.02 degree (orbit determination and maneuver performance) to assure successful recovery of the SRC. Results presented show that this requirement can be met.

Menon, Premkumar R.↗
NASA NTRS1986

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.

Swenson, B. L.↗
NASA NTRS1970

Comet rendezvous missions

Jupiter swingby trajectory analysis for comet flyby and rendezvous missions, discussing approach velocity and payloads

Manning, L. R.↗
NASA NTRS1972

Study of a comet rendezvous mission. Volume 2: Appendices

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.

Source record↗
NASA NTRS1973

The evolution of the SEP stage /SEPS/ concept

The features of a solar electric propulsion (SEP) stage are examined. An SEP stage (SEPS) contains all of the subsystems required to deliver separable payloads to the desired target and to support its own operations. These include attitude control, communications, data handling, and computer subsystems in addition to the solar array and thrust subsystems required for electric propulsion. SEPS can provide subsystem support to attached payloads for comet flyby and asteroid rendezvous. It can accommodate both planetary and geosynchronous missions by the use of mission-peculiar modules. In addition SEPS can assist the shuttle tug transportation system in earth-orbital applications. Aspects of mission analysis are discussed together with details of the electric propulsion system including solar array considerations.

Gilbert, J.↗
NASA NTRS1974

Planetary mission summaries. Volume 1: Introduction and overview

Tabular synopses of twelve missions are presented along with the Mariner Jupiter/Saturn 1977 mission for comparison. Mission definitions considered include: Mars Polar Orbiter; Mars Surface Sample Return; Mars Rover; Marine Jupiter/Uranus 1979 with Uranus Entry Probe; Mariner Jupiter Orbiter; Mariner Mercury Orbiter 1978; Early Mariner Comet Flyby Solar Electric Encke Slow Flyby; Mariner Encke Ballistic Flyby; Solar Electric Encke Rendezvous 1981; Venus Orbital Imaging Radar; Solar Electric Out-of-the-Eliptic Probe 1979. Technical conclusions of mission studies are given in order that these results may interact with the broader questions of scope, pace, and priorities in the planetary exploration program.

Source record↗
NASA NTRS1980

Chemical energy in cold-cloud aggregates - The origin of meteoritic chondrules

If interstellar particles and molecules accumulate into larger particles during the collapse of a cold cloud, the resulting aggregates contain a large store of internal chemical energy. It is here proposed that subsequent warming of these accumulates leads to a thermal runaway when exothermic chemical reactions begin within the aggregate. These, after cooling, are the crystalline chondrules found so abundantly within chondritic meteorites. Chemical energy can also heat meteoritic parent bodies of any size, and both thermal metamorphism and certain molten meteorites are proposed to have occurred in this way. If this new theory is correct, (1) the model of chemical condensation in a hot gaseous solar system is eliminated, and (2) a new way of studying the chemical evolution of the interstellar medium has been found. A simple dust experiment on a comet flyby is proposed to test some features of this controversy.

Clayton, D. D.↗
NASA NTRS1987

Use of a 2.3-GHz traveling-wave maser on the Usuda 64-meter antenna

A 2.3 GHz traveling-wave maser/closed-cycle refrigeration system was installed on the 64 m antenna at Usuda, Japan. This was done to evaluate the beam-waveguide antenna noise performance, and to support the International Cometary Explorer's (ICE's) comet flyby mission. System noise temperature at 2270 MHz was measured to be 15 K, including the maser noise contribution of 2.5 K. Maser installation and noise performance are described. The Usuda 64 m antenna is of high quality with a system operating noise temperature better than the DSN 64 m antennas.

Neff, D.↗
NASA NTRS2012

The Rotation Temperature of Methanol in Comet 103P/Hartley 2

Considered to be relics from Solar System formation, comets may provide the vital information connecting Solar Nebula and its parent molecular cloud. Study of chemical and physical properties of comets is thus important for our better understanding of the formation of Solar System. In addition, observing organic molecules in comets may provide clues fundamental to our knowledge on the formation of prebiotically important organic molecules in interstellar space, hence, may shed light on the origin of life on the early Earth. Comet 103PIHartley 2 was fIrst discovered in 1986 and had gone through apparitions in 1991, 1997, and 2004 with an orbital period of about 6 years, before its latest return in 2010. 2010 was also a special year for Comet 103PIHartley 2 because of the NASA EPOXI comet-flyby mission.

Chuang, Yo-Ling↗
NASA NTRS1996

Plasma Experiment for Planetary Exploration (PEPE)

The Plasma Experiment for Planetary Environments (PEPE) is one of the new instrument technologies being demonstrated with the New Millennium Deep Space One mission. PEPE will serve three purposes: (1) the characterization of the environment induced by the Solar Electric Propulsion (SEP) system while validating the feasibility of flying high performance plasma instrumentation on future SEP missions, (2) to carry out state-of-the-art plasma measurements in support of the scientific investigation of an asteroid and comet flyby, and (3) to validate several new plasma sensor technologies needed for future space physics and planetary missions. Details of the PEPE design are presented as well as an overview of both the technology and scientifically driven measurement objectives. The potential future applications of PEPE technology are also discussed.

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