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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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At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1997

Nucleosynthesis and the Isotopic Composition of Stardust

Various components have been isolated from carbonaceous meteorites with an isotopically anomalous elemental composition. Several of these are generally thought to represent stardust containing a nucleosynthetic record of their birthsites. This paper discusses the expected isotopic composition of stardust based upon astronomical observations and theoretical studies of their birthsites: red giants and supergiants, planetary nebulae, C-rich Wolf-Rayet stars, novae and supernovae. Analyzing the stardust budget, it is concluded that about 15% of the elements will be locked up in stardust components in the interstellar medium. This stardust will be isotopically heterogenous on an individual grain basis by factors ranging from 2 to several orders of magnitude. Since comets may have preserved a relatively unprocessed record of the stardust entering the solar nebula, isotopic studies of returned comet samples may provide valuable information on the nucleosynthetic processes taking place in the interiors of stars and the elemental evolution of the Milky Way.

Tielens, Alexander G. M.↗
NASA NTRS1999

Deep Space Control Challenges of the New Millennium

The exploration of deep space presents a variety of significant control challenges. Long communication delays coupled with challenging new science objectives require high levels of system autonomy and increasingly demanding pointing and control capabilities. Historically, missions based on the use of a large single spacecraft have been successful and popular since the early days of NASA. However, these large spacecraft missions are currently being displaced by more frequent and more focused missions based on the use of smaller and less expensive spacecraft designs. This trend drives the need to design smart software and good algorithms which together with the miniaturization of control components will improve performance while replacing the heavier and more expensive hardware used in the past. NASA's future space exploration will also include mission types that have never been attempted before, posing significant challenges to the underlying control system. This includes controlled landing on small bodies (e.g., asteroids and comets), sample return missions (where samples are brought back from other planets), robotic exploration of planetary surfaces (e.g., intelligent rovers), high precision formation flying, and deep space optical interferometry, While the control of planetary spacecraft for traditional flyby and orbiter missions are based on well-understood methodologies, control approaches for many future missions will be fundamentally different. This paradigm shift will require completely new control system development approaches, system architectures, and much greater levels of system autonomy to meet expected performance in the presence of significant environmental disturbances, and plant uncertainties. This paper will trace the motivation for these changes and will layout the approach taken to meet the new challenges. Emerging missions will be used to explain and illustrate the need for these changes.

Bayard, David S.↗
NASA NTRS2004

Computational Aerothermodynamic Design Issues for Hypersonic Vehicles

A brief review of the evolutionary progress in computational aerothermodynamics is presented. The current status of computational aerothermodynamics is then discussed, with emphasis on its capabilities and limitations for contributions to the design process of hypersonic vehicles. Some topics to be highlighted include: (1) aerodynamic coefficient predictions with emphasis on high temperature gas effects; (2) surface heating and temperature predictions for thermal protection system (TPS) design in a high temperature, thermochemical nonequilibrium environment; (3) methods for extracting and extending computational fluid dynamic (CFD) solutions for efficient utilization by all members of a multidisciplinary design team; (4) physical models; (5) validation process and error estimation; and (6) gridding and solution generation strategies. Recent experiences in the design of X-33 will be featured. Computational aerothermodynamic contributions to Mars Pathfinder, METEOR, and Stardust (Comet Sample return) will also provide context for this discussion. Some of the barriers that currently limit computational aerothermodynamics to a predominantly reactive mode in the design process will also be discussed, with the goal of providing focus for future research.

Olynick, David R.↗
NASA NTRS2004

Fallen Star

The Sept 8 mishap of the Genesis probe raised fears of the same fate happening to the Stardust comet sample return mission due to parachute into the Utah desert in 2006 with similar recovery hardware.The crash also raised a caution flag for designers of future lunar and Mars sample return missions.

Morring, Frank, Jr.↗
NASA NTRS2005

Computational Aerothermodynamic Design Issues for Hypersonic Vehicles

A brief review of the evolutionary progress in computational aerothermodynamics is presented. The current status of computational aerothermodynamics is then discussed, with emphasis on its capabilities and limitations for contributions to the design process of hypersonic vehicles. Some topics to be highlighted include: (1) aerodynamic coefficient predictions with emphasis on high temperature gas effects; (2) surface heating and temperature predictions for thermal protection system (TPS) design in a high temperature, thermochemical nonequilibrium environment; (3) methods for extracting and extending computational fluid dynamic (CFD) solutions for efficient utilization by all members of a multidisciplinary design team; (4) physical models; (5) validation process and error estimation; and (6) gridding and solution generation strategies. Recent experiences in the design of X-33 will be featured. Computational aerothermodynamic contributions to Mars Path finder, METEOR, and Stardust (Comet Sample return) will also provide context for this discussion. Some of the barriers that currently limit computational aerothermodynamics to a predominantly reactive mode in the design process will also be discussed, with the goal of providing focus for future research.

Gnoffo, Peter A.↗
NASA NTRS1997

Computational Aerothermodynamic Design Issues for Hypersonic Vehicles

A brief review of the evolutionary progress in computational aerothermodynamics is presented. The current status of computational aerothermodynamics is then discussed, with emphasis on its capabilities and limitations for contributions to the design process of hypersonic vehicles. Some topics to be highlighted include: (1) aerodynamic coefficient predictions with emphasis on high temperature gas effects; (2) surface heating and temperature predictions for thermal protection system (TPS) design in a high temperature, thermochemical nonequilibrium environment; (3) methods for extracting and extending computational fluid dynamic (CFD) solutions for efficient utilization by all members of a multidisciplinary design team; (4) physical models; (5) validation process and error estimation; and (6) gridding and solution generation strategies. Recent experiences in the design of X-33 will be featured. Computational aerothermodynamic contributions to Mars Pathfinder, METEOR, and Stardust (Comet Sample return) will also provide context for this discussion. Some of the barriers that currently limit computational aerothermodynamics to a predominantly reactive mode in the design process will also be discussed, with the goal of providing focus for future research.

Gnoffo, Peter A.↗
NASA NTRS2006

Landing and Population Hazard Analysis for Stardust Entry in Operations and Entry Planning

Stardust is a comet sample return mission that successfully returned to Earth on January 15, 2006. Stardust's targeted landing area was the Utah Test and Training Range in the Northwest corner of Utah. Requirements for the risks associated with landing were levied on Stardust by the Utah Test and Training Range and NASA. This paper describes the analysis to verify that these requirements were met and and includes calculation of debris survivability, generation of landing site selection plots, and identification of keep-out zones, as well as appropriate selection of the landing site. Operationally the risk requirements were all met for both of the GOMO-GO polls, so entry was authorized.

simulation↗
NASA NTRS1985

A preliminary analysis of a comet coma sample-return mission

It is pointed out that the exploration and characterization of comets can play a fundamental role in solar system science. Comets are probably primitive products of processes which occurred in the preplanetary solar nebula. The impending return of Halley's comet in 1986 provides an opportunity for a study of comets, and five spacecraft will be launched to intercept Halley. These spacecraft include two sent by the USSR, two by Japan, and one by the European Space Agency (ESA). NASA has recommended two programs for the exploration and characterization of comets. The first mission considered would be a rendezvous with a short-period comet, while the second mission would provide for the return to earth of a sample of the volatile and nonvolatile constituents of the coma of a comet. Developments related to these plans are discussed.

Swenson, B. L.↗
NASA NTRS2006

Mineralogy and Petrology of COMET WILD2 Nucleus Samples

The sample return capsule of the Stardust spacecraft will be recovered in northern Utah on January 15, 2006, and under nominal conditions it will be delivered to the new Stardust Curation Laboratory at the Johnson Space Center two days later. Within the first week we plan to begin the harvesting of aerogel cells, and the comet nucleus samples they contain for detailed analysis. By the time of the LPSC meeting we will have been analyzing selected removed grains for more than one month. This presentation will present the first results from the mineralogical and petrological analyses that will have been performed.

Zolensky, Michael↗
NASA NTRS1992

Comet nucleus and asteroid sample return missions

During the 1991-92 academic year, the Pennsylvania State University has developed three sample return missions: one to the nucleus of comet Wild 2, one to the asteroid Eros, and one to three asteroids located in the Main Belt. The primary objective of the comet nucleus sample return mission is to rendezvous with a short period comet and acquire a 10 kg sample for return to Earth. Upon rendezvous with the comet, a tethered coring and sampler drill will contact the surface and extract a two-meter core sample from the target site. Before the spacecraft returns to Earth, a monitoring penetrator containing scientific instruments will be deployed for gathering long-term data about the comet. A single asteroid sample return mission to the asteroid 433 Eros (chosen for proximity and launch opportunities) will extract a sample from the asteroid surface for return to Earth. To limit overall mission cost, most of the mission design uses current technologies, except the sampler drill design. The multiple asteroid sample return mission could best be characterized through its use of future technology including an optical communications system, a nuclear power reactor, and a low-thrust propulsion system. A low-thrust trajectory optimization code (QuickTop 2) obtained from the NASA LeRC helped in planning the size of major subsystem components, as well as the trajectory between targets.

Melton, Robert G.↗
NASA NTRSDate not supplied

Comet Wild 2 Sample Track 3D Images and S-XRF Stereo Maps

The NASA Stardust mission to comet Wild 2 returned to Earth in 2006 with cometary material trapped in aerogel. The cometary particles were captured at a relative velocity of 6.1 km/s, creating three-dimensional (3D) tracks containing void space, compressed aerogel, melted aerogel, and fragmented cometary material. Each track represents a unique hypervelocity impact event. The nature of each track forming event, including the original state of the impactor, is recorded in 3D track morphology and material distribution. Tracks were cut from sampling tiles in thin aerogel “keystones” translucent to optical light.

D. S. Ebel↗
NASA NTRS1987

Study of sampling systems for comets and Mars

Several aspects of the techniques that can be applied to acquisition and preservation of samples from Mars and a cometary nucleus were examined. Scientific approaches to sampling, grounded in proven engineering methods are the key to achieving the maximum science value from the sample return mission. If development of these approaches for collecting and preserving does not preceed mission definition, it is likely that only suboptimal techniques will be available because of the constraints of formal schedule timelines and the normal pressure to select only the most conservative and least sophisticated approaches when development has lagged the mission milestones. With a reasonable investment now, before the final mission definition, the sampling approach can become highly developed, ready for implementation, and mature enough to help set the requirements for the mission hardware and its performance.

Amundsen, R. J.↗
NASA NTRS2006

Elemental Compositions of Comet 81P/Wild 2 Samples Collected by Stardust

We measured the chemical compositions of material from 23 particles in aerogel and residue in 7 craters in aluminum foil, collected during passage of the Stardust spacecraft through the coma of Comet 81P/Wild 2. These particles are chemically heterogeneous at the largest size-scale analyzed, ~180 nanograms. The mean chemical composition of this Wild 2 material agrees with the CI meteorite composition for the refractory elements Mg, Si, Cr, Fe, and Ni to 35%, and for Ca and Mn to 50%. The data suggest the moderately volatile elements Cu, Zn, and Ga may be enriched in this Wild 2 material.

Flynn, G. J.↗
NASA NTRS1987

A survey of tether applications to planetary exploration

Concepts for the use of tethers in various hypothetical astronomical research missions are discussed. Tethers used to study the atmospheres of Venus and Mars and the magnetosphere of Jupiter are examined, and possible orbiting tether systems at the moon and Mars are shown and described. A tether method for collecting a sample from Comet Halley is addressed along with a system for hovering near a comet. A multiple sample return system for asteroids is described, and a heliocentric Alfven engine concept to study the solar wind is discussed.

Penzo, Paul A.↗
NASA NTRS1987

Expert system isssues in automated, autonomous space vehicle rendezvous

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.

Goodwin, Mary Ann↗