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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 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

A survey of possible missions to the periodic comets in the interval 1974 - 2010

Catalogs are developed to survey the mission possibilities for the short period comets. In the first the physical and pertinent orbital characteristics are given for 65 short period comets. The second catalog is one containing the predicted perihelia for each of the 65 comets between 1974 and 2010. Geometry is included to indicate feasibility of Earth-based observation and sighting within 100 days of perihelion. The comets are divided on the basis of size and activity into three groups from the data in the first catalog: primary, secondary and low interest. The perihelia are separated into two groups: satisfactory and not satisfactory on the basis of earth-comet distance.

Bender, D. F.↗
NASA NTRS2006

Solar Electric Propulsion for Primitive Body Science Missions

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.

Witzberger, Kevin E.↗
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 NTRS1973

Study of 1980 Comet Encke-asteroid missions using a spin-stabilized spacecraft. Volume 1: Summary report

As a contribution to improved understanding of early comet exploration options, independent studies were undertaken which resulted in the identification of a number of fast flyby mission options for the 1980 apparition of Encke. The primary impetus for this approach was the prospect of utilizing existing launch vehicles and conventional spacecraft technology. In addition, timely experience and scientific data gained through an early fast flyby could prove valuable in implementing more ambitious succeeding missions, including a flyby of Comet Halley in 1986.

Bursnall, W. J.↗
NASA NTRS1990

Aerobraking strategies for the sample of comet coma earth return mission

The results of a study to the validate the applicability of the aerobraking concept to the SOCCER (sample of comet coma earth return) mission using a six-DOF computer simulation of the aerobraking process are presented. The SOCCER spacecraft and the aerobraking scenario and power supply problem are briefly described. Results are presented for the spin effect, payload exposure problem, and sun angle effect.

Abe, Takashi↗
NASA NTRS2004

Application of Solar Electric Propulsion to a Comet Surface Sample Return Mission

Current NSTAR (planned for the Discovery Mission: Dawn) and NASA's Evolutionary Xenon Thruster based propulsion systems were compared for a comet surface sample return mission to Tempe1 1. Mission and systems analyses were conducted over a range of array power for each propulsion system with an array of 12 kW EOL at 1 AU chosen for a baseline. Engine configurations investigated for NSTAR included 4 operational engines with 1 spare and 5 operational engines with 1 spare. The NEXT configuration investigated included 2 operational engines plus 1 spare, with performance estimated for high thrust and high Isp throttling modes. Figures of merit for this comparison include Solar Electric Propulsion dry mass, average engine throughput, and net non-propulsion payload returned to Earth flyby.

Cupples, Mike↗
NASA NTRS1991

Thermal modeling of comet Kopff: Implications for the CRAF mission

A thermal model of periodic comet Kopff was developed to aid in planning for the Comet Rendezvous Asteroid Flyby mission. The model is based on the comet nucleus model, which estimates the surface temperature distribution and sublimation rates on a rotating icy sphere in heliocentric orbit. The model results are compared with the observed gas production rates from Kopff in 1983. It is found that approximately 15 percent of the sunlit nucleus surface is active, a relatively high fraction for a typical short-period comet. This suggests that the actual nucleus radius may be larger than the model value. The slope of the observed gas production curve with heliocentric distance is steeper than that predicted by the thermal model. This may indicate the existence of a more complex process than direct sublimation of surface ices, such as gas diffusion through a nonvolatile insulating crust.

Weissman, Paul↗
NASA NTRS1975

Improved planetary orbit mission capabilities in the Shuttle era by use of space-storable propulsion systems

Planetary-orbit mission capabilities will be greatly improved by the advent of space-storable retropropulsion systems with liquid fluorine and hydrazine as bipropellants even when the Shuttle/Tug is used as launch vehicle. Having a specific impulse as large as 375 sec, a multimission propulsion module using space-storable propellants with Pioneer or Mariner spacecraft as payload can perform Mercury, Saturn, and Uranus orbiter missions, and even some comet rendezvous missions, more cost effectively and flexibly than one using earth-storable propellants. It also can reduce trip time to the outer planets significantly. This paper presents mission requirements, technology status, system design and performance, development schedules, and costs based on data derived in a recent design and feasibility study.

Meissinger, H. F.↗
NASA NTRS1975

Advanced bipropellant systems for use on planetary orbiters

Planetary orbit mission capabilities will be greatly improved by the advent of space-storable retro-propulsion systems with liquid fluorine/hydrazine as bipropellants, even when the Space Shuttle/Space Tug is used as launch vehicle. With a specific impulse as high as 375 sec, a multimission propulsion module designed for Pioneer or Mariner class spacecraft as payload and using space-storable propellants, can perform Mercury, Saturn and Uranus orbiter missions, and even some comet rendezvous missions. It also can reduce trip times to the outer planets significantly. The paper presents mission requirements, propulsion technology status, system design, performance, development schedules and cost data, based on results of a recent design and feasibility study.

Meissinger, H. F.↗
NASA NTRS1974

Mission design for a ballistic slow flyby Comet Encke 1980

Preliminary mission analyses for a proposed 1980 slow flyby (7-9 km/s) of comet Encke are presented. Among the topics covered are science objectives, Encke's physical activity and ephemeris accuracy, trajectory and launch-window analysis, terminal guidance, and spacecraft concepts. The nominal mission plan calls for a near-perihelion intercept with two spacecraft launched on a single launch vehicle. Both spacecraft will arrive at the same time, one passing within 500 km from Encke's nucleus on its sunward side, the other cutting through the tail region. By applying a small propulsive correction about three weeks after the encounter, it is possible to retarget both spacecraft for a second Encke intercept in 1984. The potential science return from the ballistic slow flyby is compared with other proposed mission modes for the 1980 Encke flyby mission, including the widely advocated slow flyby using solar-electric propulsion. It is shown that the ballistic slow flyby is superior in every respect.

Farquhar, R. W.↗
NASA NTRS1989

Combined microwave science and propulsion

The combined use of high-power active science instruments and high-power electric propulsion is investigated with a view to new science opportunities and measurements on future planetary missions. An example of a comet rendezvous mission that could benefit from this combination is discussed. It was found that, with electric propulsion, the launch mass of the comet spacecraft could be reduced by 61-68 percent over the chemical propulsion baseline mission. This high-power spacecraft is also capable of delivering a significant high-power radar science payload to the comet.

Palaszewski, Bryan↗
NASA NTRS1990

The CRAF mission and Earth-based comet observations

The Comet Rendezvous Asteroid Flyby (CRAF) mission is now being designed and planned to perform detailed studies of a typical short period comet as it moves around its orbit, building on the data gained from the Giotto, Vega, and Suisei fast flybys of Comet Halley in 1986. CRAF will be launched in Aug. 1995 and will match orbits with short period Comet Kopff in July 2000, 850 days before perihelion at a heliocentric distance of 5.05 AU. After a series of close, slow flybys, the spacecraft will be placed in orbit around the nucleus for a better than 1 m/line-pair imaging resolution on the nucleus surface. Earth based observations of the target comet, either by ground based facilities or Earth orbiting satellites, can provide essential data for CRAF mission planning, and are needed in support of the rendezvous mission. Estimates of the nucleus size, albedo, shape, rotation period, and rotation pole orientation are needed for preliminary mission planning, resource allocation, and sequence design.

Weissman, Paul R.↗
NASA NTRS1978

Solar sailing - The concept made realistic

The practicability of using solar sails as a means of spacecraft propulsion is discussed with reference to a Haley's comet rendezvous mission in 1981. Two types of sails are examined: square and heliogyro. Because of ease of deployment (release into space from a space shuttle, and unfolding of the blades through solar radiation pressure) the latter is preferred. Structural and mission parameters are given for the heliogyro configuration, with attention to operational temperature limits and material coefficients. A cranking orbit is described, where a sail-powered spacecraft flies first toward the sun, and then away from it in order to achieve rendezvous with a comet. Other missions using solar sails, including a back-up mission to Encke's comet in 1983, are also discussed.

Friedman, L.↗
NASA NTRS2017

Detailed Design of an Earth Entry Vehicle for Comet Surface Sample Return

The 2013 Decadal Survey for New Frontiers missions identifies several high-value science missions, including Comet Surface Sample Return (CSSR). A CSSR mission will advance the scientific community's fundamental understanding of the origin of the solar system and the contribution of comets to the volatile inventory of the Earth. An entry capsule, or earth entry vehicle (EEV), is be required to protect the scientific payload from the extreme conditions of atmospheric entry, descent, and landing. The Decadal Survey Mission Concept Study along with an APL (Johns Hopkins University Applied Physics Lab) 2007-2008 Comet Surface Sample Mission Study details several of the driving requirements for a CSSR EEV; these include a payload volume and mass and inertial entry velocity of 9 kilometers per second. The mission concept study selected a Multi-Mission Earth Entry Vehicle (MMEEV) design concept derived from the Mars Sample Return (MSR) entry capsule design because of its increased reliability over a parachute-based vehicle. This presentation will explore detailed design of a CSSR-capable Earth Entry Vehicle, including trajectories, aeroheating predictions and associated thermal protection system masses, and onboard instrumentation for entry science.

Trajectory Analysis↗
NASA NTRS2021

Modelling the Water and Carbon Dioxide Production Rates of Comet 67P/Churyumov-Gerasimenko

The European Space Agency Rosetta/Philae mission to Comet 67P/Churyumov–Gerasimenko in 2014–2016 is the most complete and diverse investigation of a comet carried out thus far. Yet, many physical and chemical properties of the comet remain uncertain or unknown, and cometary activity is still not a well–understood phenomenon. We here attempt to place constraints on the nucleus abundances and sublimation front depths of H 2 O and CO 2 ice, and to reconstruct how the nucleus evolved throughout the perihelion passage. We employ the thermophysical modelling code ‘Numerical Icy Minor Body evolUtion Simulator’, or NIMBUS, to search for conditions under which the observed H 2 O and CO 2 production rates are simultaneously reproduced before and after perihelion. We find that the refractories to water–ice mass ratio of relatively pristine nucleus material is μ ≈ 1, that airfall material has μ ≈ 2, and that the molar abundance of CO 2 relative H 2 O is near 30 per cent. The dust mantle thickness is typically ≲ 2 cm. The average CO 2 sublimation front depths near aphelion were ~ 3.8 m and ~ 1.9 m on the northern and southern hemispheres, respectively, but varied substantially with time. We propose that airfall material is subjected to substantial fragmentation and pulverisation due to thermal fatigue during the aphelion passage. Sub–surface compaction of material due to CO 2 activity near perihelion seems to have reduced the diffusivity in a measurable way.

67P/Churyumov–Gerasimenko↗
NASA NTRS1981

Mission options for the first SEPS application

Missions to comets and asteroids are primary candidates for Solar Electric Propulsion System (SEPS) applications. NASA estimates that the first SEPS mission might be launched as early as 1988. This paper presents mission opportunities available for launches between 1988 and early 1991 and discusses the performance capabilities of the current SEPS. Use of a Shuttle Two-Stage IUS and/or a Shuttle Wide Tank Centaur launch vehicle is assumed in the performance assessment. The list of possible first SEPS missions consists of nine missions to comets of primary interest and examples of multiple asteroid rendezvous missions. Both an earth crossing asteroid and a main belt asteroid are considered as first possible targets in the multiple asteroid rendezvous examples. Mission opportunity and performance maps for Eros and Anteros are presented which provide exact performance data and optimal launch and arrival dates for any launch year.

Yen, C.-W. L.↗
NASA NTRS1976

Comparison of candidate solar array maximum power utilization approaches

A study was made of five potential approaches that can be utilized to detect the maximum power point of a solar array while sustaining operations at or near maximum power and without endangering stability or causing array voltage collapse. The approaches studied included: (1) dynamic impedance comparator, (2) reference array measurement, (3) onset of solar array voltage collapse detection, (4) parallel tracker, and (5) direct measurement. The study analyzed the feasibility and adaptability of these approaches to a future solar electric propulsion (SEP) mission, and, specifically, to a comet rendezvous mission. Such missions presented the most challenging requirements to a spacecraft power subsystem in terms of power management over large solar intensity ranges of 1.0 to 3.5 AU. The dynamic impedance approach was found to have the highest figure of merit, and the reference array approach followed closely behind. The results are applicable to terrestrial solar power systems as well as to other than SEP space missions.

Costogue, E. N.↗