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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 271 records · Page 15

Space nuclear safety from a user's viewpoint

The National Aeronautics and Space Administration (NASA) launched the Jet Propulsion Laboratory's (JPL) two Voyager spacecraft to Jupiter in 1977, each using three radioisotope thermoelectric generators (RTGs) supplied by the Department of Energy (DOE) for onboard electric power. In 1986 NASA will launch JPL's Galileo spacecraft to Jupiter equipped with two DOE supplied RTGs of an improved design. NASA and JPL are also responsible for obtaining a single RTG of this type from DOE and supplying it to the European Space Agency as part of its participation in the International Solar Polar Mission. As a result of these missions, JPL has been deeply involved in space nuclear safety as a user. This paper will give a brief review of the user contributions by JPL - and NASA in general - to the nuclear safety processes and relate them to the overall nuclear safety program necessary for the launch of an RTG. The two major safety areas requiring user support are the ground operations involving RTGs at the launch site and the failure modes and probabilities associated with launch accidents.

Campbell, R. W.↗

MONTE Python for Deep Space Navigation

The Mission Analysis, Operations, and Navigation Toolkit Environment (MONTE) is the Jet Propulsion Laboratory’s (JPL) signature astrodynamic computing platform. It was built to support JPL’s deep space exploration program, and has been used to fly robotic spacecraft to Mars, Jupiter, Saturn, Ceres, and many solar system small bodies. At its core, MONTE consists of low-level astrodynamic libraries that are written in C++ and presented to the end user as an importable Python language module. These libraries form the basis on which Python-language applications are built for specific astrodynamic applications, such as trajectory design and optimization, orbit determination, flight path control, and more. The first half of this paper gives context to the MONTE project by outlining its history, the field of deep space navigation and where MONTE fits into the current Python landscape. The second half gives an overview of the main MONTE libraries and provides a narrative example of how it can be used for astrodynamic analysis.

aerospace↗

Europa lander mission concept power architecture

The Europa Lander mission concept team seeks to optimize a power system architecture to search for evidence of life on the surface of Europa, an icy moon of Jupiter. Environmental and mission challenges included radiation, extreme low temperatures, planetary protection, mission duration, and the limitations of the launch vehicle. Leveraging heritage from NASA’s Europa Clipper mission, the baseline architecture is highly reliable, capable of meeting all science objectives, and comprises of three vehicles: a solar powered carrier stage, a secondary battery powered descent vehicle, and a primary battery powered lander.

Carr, Gregory↗

Exploring Jupiter and its satellites with an orbiter

Review of the initial studies that define a challenging Mariner Jupiter Orbiter mission. Elegant and precise astrodynamics are shown to make possible a bravura examination of the entire Jovian system with two Mariner-class spacecraft to be launched in 1981. This mission is expected to advance considerably our understanding of the origin and evolution of the solar system.

Beckman, J. C.↗

A versatile detector system to measure the change states, mass compositions and energy spectra of interplanetary and magnetosphere ions

An instrument is described for measuring the mass and charge state composition as well as the energy spectra and angular distributions of 0.5 to 350 kev/charge ions in interplanetary space and in magnetospheres of planets such as Jupiter and earth. Electrostatic deflection combined with a time-of-flight and energy measurement allows three-parameter analysis of output signals from which the mass, charge states, and energy are determined. Post-acceleration by 30 kV extends the energy range of the detector system into the solar wind and magnetosphere plasma regime. Isotopes of H and He are easily resolved as are individual elements up to Ne and the dominant elements up to and including Fe. This instrument has an extremely large dynamic range in intensity and is sensitive to rare elements even in the presence of high intensity radiation, and is adapted for interplanetary, deep-space, and out-of-the-ecliptic missions, as well as for flights on spacecraft orbiting Jupiter and earth.

Gloeckler, G.↗

Nuclear Electric Propulsion for Outer Space Missions

Today we know of 66 moons in our very own Solar System, and many of these have atmospheres and oceans. In addition, the Hubble (optical) Space Telescope has helped us to discover a total of 100 extra-solar planets, i.e., planets going around other suns, including several solar systems. The Chandra (X-ray) Space Telescope has helped us to discover 33 Black Holes. There are some extremely fascinating things out there in our Universe to explore. In order to travel greater distances into our Universe, and to reach planetary bodies in our Solar System in much less time, new and innovative space propulsion systems must be developed. To this end NASA has created the Prometheus Program. When one considers space missions to the outer edges of our Solar System and far beyond, our Sun cannot be relied on to produce the required spacecraft (s/c) power. Solar energy diminishes as the square of the distance from the Sun. At Mars it is only 43% of that at Earth. At Jupiter, it falls off to only 3.6% of Earth's. By the time we get out to Pluto, solar energy is only .066% what it is on Earth. Therefore, beyond the orbit of Mars, it is not practical to depend on solar power for a s/c. However, the farther out we go the more power we need to heat the s/c and to transmit data back to Earth over the long distances. On Earth, knowledge is power. In the outer Solar System, power is knowledge. It is important that the public be made aware of the tremendous space benefits offered by Nuclear Electric Propulsion (NEP) and the minimal risk it poses to our environment. This paper presents an overview of the reasons for NEP systems, along with their basic components including the reactor, power conversion units (both static and dynamic), electric thrusters, and the launch safety of the NEP system.

Barret, Chris↗

Predicting the Atmospheric Composition of Extrasolar Giant Planets

To date, approximately 120 planet-sized objects have been discovered around other stars, mostly through the radial-velocity technique. This technique can provide information about a planet s minimum mass and its orbital period and distance; however, few other planetary data can be obtained at this point in time unless we are fortunate enough to find an extrasolar giant planet that transits its parent star (i.e., the orbit is edge-on as seen from Earth). In that situation, many physical properties of the planet and its parent star can be determined, including some compositional information. Our prospects of directly obtaining spectra from extrasolar planets may improve in the near future, through missions like NASA's Terrestrial Planet Finder. Most of the extrasolar giant planets (EGPs) discovered so far have masses equal to or greater than Jupiter's mass, and roughly 16% have orbital radii less than 0.1 AU - extremely close to the parent star by our own Solar-System standards (note that Mercury is located at a mean distance of 0.39 AU and Jupiter at 5.2 AU from the Sun). Although all EGPs are expected to have hydrogen-dominated atmospheres similar to Jupiter, the orbital distance can strongly affect the planet's temperature, physical, chemical, and spectral properties, and the abundance of minor, detectable atmospheric constituents. Thermochemical equilibrium models can provide good zero-order predictions for the atmospheric composition of EGPs. However, both the composition and spectral properties will depend in large part on disequilibrium processes like photochemistry, chemical kinetics, atmospheric transport, and haze formation. We have developed a photochemical kinetics, radiative transfer, and 1-D vertical transport model to study the atmospheric composition of EGPs. The chemical reaction list contains H-, C-, O-, and N-bearing species and is designed to be valid for atmospheric temperatures ranging from 100-3000 K and pressures up to 50 bar. Here we examine the effect of stellar distance (e.g., incident ultraviolet flux, atmospheric temperature) on the chemical properties of EGPs. The model is applied to two generic Class II and III intermediate temperature EGPs located at 3.3 and 0.27 AU from a solar-like parent star, and the results are compared with a model for Jupiter at 5.2 AU.

Sharp, A. G.↗

The Three-Dimensional Nature of Interaction Regions: Pioneer, Voyager, and Ulysses fro 1 to 5 AU: Solar Cycle Variations

We investigated diverse aspects of the interaction regions detected by four spacecraft that travelled from Earth to Jupiter at different phases of the solar cycle: Pioneer 11 (declining phase of cycle 20); voyagers 1 and 2 (ascending phase of cycle 21); and Ulysses (just after solar maximum 22). From the analysis of 38 stream interfaces we found that the interaction regions detected by the three missions have different geometries.

stream interfaces solar winds solar wind streams↗

(abstract) A Low-Cost Mission to 2060 Chiron Based on the Pluto Fast Flyby

The Pluto Fast Flyby-based mission to Chiron described in this paper is a low cost, scientifically rewarding, focused mission in the outer solar system. The proposed mission will make a flyby of 2060 Chiron, an active 'comet' with over 10(sup 4) times the mass of Halley, and an eccentric, Saturn-crossing orbit which ranges from 8.5 to 19 AU. This mission concept achieves the flyby 4.2 years after launch on a direct trajectory from Earth, is independent of Jupiter launch windows, and fits within Discovery cost guidelines. This mission offers the scientific opportunity to examine a class of object left unsampled by the trail-blazing Mariners, Pioneers, Voyagers, and missions to Halley. Spacecraft reconnaissance of Chiron addresses unique objectives relating to cometary science, other small bodies, the structure of quasi-bound atmospheres on modest-sized bodies, and the origin of primitive bodies and the giant planets. Owing to Chiron's large size (180<D<370 km), unique nature, and unusual orbit, this mission is likely to draw significant public interest. As described by COMPLEX, the SSEC, and later the SSES, flybys are the appropriate scale missions for initial reconnaissance missions. Carrying three sophisticated instruments, the proposed flyby will return critical data about Chiron's size, shape, polar obliquity, atmosphere, surface morphology, surface composition, internal structure, surface activity (including the nature of Chiron's outbursts), and origin. Engineering analysis indicates that the spacecraft is capable of navigating to and encountering Chiron at close approach distances of less than 5 000 km, well inside the 50 000 to 150 000 km coma, and perhaps within the collisional chemistry zone of the coma. The low cost of the proposed Chiron mission is based on the opportunity to use the planned Pluto Flyby spare spacecraft and a Proton Expendable Launch Vehicle (ELV) (the pluto spacecraft is being designed to be compatible with a Proton launch). Backup launch opportunities on Delta II and Atlas ELVs are available. The Pluto Fast Flyby mission plans to develop a low cost ($150M), lightweight (<150 kg) outer planet spacecraft which is well suited to flyby reconnaissance in the outer solar system. This Chiron flyby mission is designed to leverage SSED's Pluto spacecraft investment into a scientifically valuable successor mission within the Discovery cost cap. Taking advantage of the spare spacecraft, we estimate the Discovery Chiron intercept mission can be launched for less than $100 M. We believe this makes a highly attractive proposal, which maintains US presence and leadership in the study of the outer solar system, and enables the first-time exploration of a wholly new class of planetary target, an outer solar system planetesimal.

2060 Chiron planetesimal flyby Pluto Fast Flyby sp↗

The 1981 Jupiter Orbiter Probe mission

Plans for the 1981 Jupiter Orbiter Probe (JOP) mission are presented in some detail. The need for a Jupiter entry probe, remote sensing of the planet, and an orbiter, in addition to flybys, is made clear. Launch hardware, using the Space Shuttle flight system and Interim Upper Stage, is described, along with scientific tasks laid out for the entry probe and the orbiter. Combined analysis of the Jovian magnetosphere and other orbiter missions calls for a two-part orbiter with one part spun and the other de-spun. Related design problems and solutions are described and diagrammed. Jovian moon flybys and orbiter path adjustments by subsequent earth-launched flybys are discussed. The importance of Jupiter data for solar system evolution and possible analysis of early stages of stellar evolution or of a binary system are also treated.

Moore, J. W.↗

Retrospective Observations of the Solar System Planets with Interstellar Probe

Retrospective Observations of the Solar System Planets with Interstellar Probe The Interstellar Probe (ISP) mission concept could simultaneously explore a number of long-standing solar system and exoplanetary science objectives. ISP’s long mission lifetime, in combination with the large separations from the solar system objects it could observe (Fig. 1), affords a truly unique dataset. This data could be leveraged to validate models of solar system and extrasolar planets and would be directly analogous to observations we can expect to make for exoplanets. Taken together, these opportunities suggest that ISP’s mission is a critical and necessary component for future planetary science endeavors. This abstract aims to address some of the clear synergies between ISP’s mission profile and the gaps in solar system science that are necessarily gaps in our ability to wholly bound our expectations for exoplanet observations (partly discussed in several white papers, including Zemcov et al., 2019; Harman et al., 2020). Notably, no single platform has yet returned near-complete phase curves for the majority of solar system planets. This is partly due to observational constraints (e.g., ground-based observatories can observe a maximum phase angle of Jupiter, Saturn, Uranus, and Neptune of 12º, 6º, 3º, and 2º, respectively; Mallama and Hilton, 2018), but also because of the sparse nature of observations captured by spacecraft over the last 40 years (e.g., Pollack et al., 1986). Additionally, these observations come from disparate instruments that have their own biases and limitations, whereas observations by ISP’s instrumentation would provide almost uniform measurements of nearly every solar system object, removing much of the uncertainty when it comes to data intercomparisons. The biggest hurdles for making these measurements from ISP are likely to be the tight mass and energy limitations, as well as the technical challenge of looking as close as possible to the Sun without peering directly at it. This is potentially complicated by the nature of the larger astrophysical mission requirements, including whether the spacecraft is spinning, but integrating observations on board before returning them to Earth serves to both partly mitigate both the possibility of a spinning spacecraft and the downlink volumes for lookback data (although it may make data disaggregation more technically challenging). Ultimately, ISP could return truly innovative observational data of our solar system, in furtherance of a number of planetary and solar system science goals.

Sonny Harman↗

Modern Exploration of Galileo's New Worlds

Four hundred years ago Galileo turned his telescope to the heavens and changed the way we view the cosmos forever. Among his discoveries in January of 1610 were four new 'stars', following Jupiter in the sky but changing their positions with respect to the giant planet every night. Galileo showed that these 'Medicean stars', as he named them, were moons orbiting Jupiter in the same manner that the Earth and planets revolve about the Sun in the Copernican theory of the solar system. Over the next three centuries these moons, now collectively named the Galilean satellites after their discoverer, remained tiny dots of light in astronomers' telescopes. In the latter portion of the twentieth century Galileo's new worlds became important targets of exploration by robotic spacecraft. This paper reviews the history of this exploration through the discoveries made by the Galileo mission from 1995 to 2003, setting the stage for on-going exploration in the new century.

space vehicles↗

Mariner Jupiter/Saturn 1977 - The mission frame.

Following the cancellation of the Outer Planet Grand Tour Project, NASA and JPL examined less ambitious, alternative missions for exploring the outer planets. The mission that proved most attractive scientifically and fits within the projected NASA budget constraints embraces dual flights to Jupiter and Saturn, with launch in 1977. NASA has implemented it as the Mariner Jupiter/Saturn 1977 (MJS77) Project. The MJS77 mission covers exploratory investigations of the Jupiter and Saturn planetary systems and the interplanetary medium out to Saturn. Items of special interest include Jupiter's great red spot, the question of Io's anomalous brightening and phenomena associated with its EM behavior. After Saturn encounter, the spacecraft will escape the solar system in the general direction of the solar apex.

Bourke, R. D.↗

Studies of chemical abundances in the outer solar system

Ground-based observations and the Pioneer 10 mission have led to new discoveries and revisions of previous ideas about the outer solar system. Among these are the discovery of atmospheres on Io and Ganymede, emission from sodium and hydrogen in a cloud around Io, and the presence of acetylene, ethane, and phosphine in the atmosphere of Jupiter. Titan, the largest satellite of Saturn, continues to be an extremely interesting and baffling object, clearly very different in composition from the bodies familiar with in the inner solar system - which is also true of Ganymede and Callisto. New data on the abundances of methane and hydrogen in the atmospheres of Uranus and Neptune suggest that the values of C/H in these atmospheres may be much lower than had been previously thought. This result reinforces the apparent compositional difference between these two planets and Jupiter and Saturn, whose atmospheres exhibit a near-solar value for this ratio.

Owen, T.↗

Jupiter orbiter lifetime: The hazard of Galilean satellite collision

The four Galilean satellites of Jupiter present a long-term collision hazard to an uncontrolled orbiting spacecraft that repeatedly enters the spatial region occupied by the satellites. Satellite close encounters and the likelihood of collision over a wide range of initial orbit conditions were analyzed. The effect of orbit inclination was of key interest. The scope of the analysis was restricted to orbital dynamic considerations alone, i.e. the question of biological contamination given the event of collision was not considered. A quarantine or orbiter lifetime of 50 years was assumed. This time period begins at spacecraft shutdown following completion of the mission objectives. A numerical approach was adopted wherein each initial orbit is propagated for 50 years, and satellite closest encounter distances recorded on every revolution. The computer program includes approximations of the three major perturbation effects on the long-term motion of the orbiter: (1) Jupiter oblateness, (2) solar gravity, and (3) satellite gravity.

Friedlander, A. L.↗

Studies of chemical abundances in the outer solar system

Ground-based observations and the Pioneer 10 mission have led to new discoveries and revisions of previous ideas about the outer solar system. Among these are the discovery of atmospheres on lo and Ganymede, emission from sodium and hydrogen in a cloud around lo, and the presence of acetylene, ethane, and phosphine in the atmosphere of Jupiter. Titan, the largest satellite of Saturn, continues to be an extremely interesting and baffling object, clearly very different in composition from the bodies we are familiar with in the inner solar system; this is also true of Ganymede and Callisto. New data on the abundances of methane and hydrogen in the atmospheres of Uranus and Neptune suggest that the values of C/H in these atmospheres may be much lower than had been previously thought. This result reinforces the apparent compositional differences between these two planets and Jupiter and Saturn, whose atmospheres exhibit a near-solar value for this ratio.

Owen, T.↗

Ulysses at Jupiter - An overview of the encounter

Preliminary scientific findings of the Ulysses mission that was launched in October 1990 and arrived at Jupiter in Februrary 1992 are reviewed. The mission was aimed at using the gravity field of Jupiter to redirect the spacecraft to the sun's polar regions, which will be traversed in 1994 and 1995. Major results include possible entry into the polar cap; the identification of magnetospheric ions originating from Jupiter's ionsphere; Io, and the solar wind; observation of longitudinal asymmetries in density and discrete wave-emitting regions of the Io plasma torus; the presence of counter-streaming ions and electrons, field-aligned currents, and energetic electron and radio bursts in the dusk sector on high-latitude magnetic field lines; and the identification of the magnetic field direction in the dusk sector, which is indicative of tailward convection.

Smith, E. J.↗

Ultraviolet spectrometer experiment for the Voyager mission

An objective grating spectrometer covering the wavelength range of 500 to 1700 A with a 10-A resolution is employed for the Voyager ultraviolet spectrometer experiment. In determining the composition and structure of the atmospheres of Saturn, Jupiter and several satellites, the ultraviolet spectrometer will rely on airglow mode observations to measure radiation from the atmospheres due to resonant scattering of solar flux, and the occultation mode for assessments of the atmospheric extinction of solar or stellar radiation as the spacecraft enters shadow zones. Since it is capable of prolonged stellar observations in the 500 to 1000 A wavelength range, the spectrometer is expected to make important contributions to exploratory studies of UV sources.

Broadfoot, A. L.↗