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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 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Engineering models of the Venus atmosphere.

Engineering models of the Venus atmosphere are presented for use in spacecraft design and mission planning. The models are developed from (1) data measured by the U.S. Mariner 5 and USSR Venera spacecraft, (2) earth-based measurements, and (3) theory which best satisfies the observations. The models include a most probable model and models for extremes of molecular mass and solar activity. In addition to the basic engineering models, other atmospheric characteristics and parameters affecting the models are discussed including planetary radius, atmospheric composition and clouds.

Noll, R. B.↗
NASA NTRS1984

Concepts used in the preparation of the document - Space and planetary environment criteria guidelines for use in space vehicle development 1982 revision

The NASA/Marshall Space Flight Center has developed a series of documents concerning space and planetary environments for use in the formulation of aerospace vehicle and spacecraft design criteria. For the earth above 90km altitude, and for the moon, planets, and other bodies in the Solar System; information is provided in disciplinary area of importance to the spacecraft designer such as planetary geology and morphology, atmospheric and ionospheric structures, radiation, particles, geomagnetic fields, astrodynamic constants, and meteoroids. This paper presents the philosophy used in the preparation of the current (1982) version of the document. Specific topics will be discussed in relation to their significance for aerospace vehicle and spacecraft development and mission analysis.

Davis, M. H.↗
NASA NTRS2018

Exoplanet Classification and Yield Estimates for Direct Imaging Missions

Future NASA concept missions that are currently under study, like the Habitable Exoplanet Imaging Mission (HabEx) and the Large Ultra-violet Optical Infra Red Surveyor (UVOIR), could discover a large diversity of exoplanets. We propose here a classification scheme that distinguishes exoplanets into different categories based on their size and incident stellar flux, for the purpose of providing the expected number of exoplanets observed (yield) with direct imaging missions. The boundaries of this classification can be computed using the known chemical behavior of gases and condensates at different pressures and temperatures in a planetary atmosphere. In this study, we initially focus on condensation curves for sphalerite ZnS, H2O, CO2, and CH4. The order in which these species condense in a planetary atmosphere define the boundaries between different classes of planets. Broadly, the planets are divided into rocky planets (0.5-1.0 solar radius), super-Earths (1.0-1.75 solar radius), sub-Neptunes (1.75-3.5 solar radius), sub-Jovians (3.5-6.0 solar radius), and Jovians (6-14.3 solar radius) based on their planet sizes, and "hot," "warm," and "cold" based on the incident stellar flux. We then calculate planet occurrence rates within these boundaries for different kinds of exoplanets, eta (sub planet) [i.e. exoplanet], using the community coordinated results of NASA's Exoplanet Program Analysis Group's Science Analysis Group-13 (SAG-13). These occurrence rate estimates are in turn used to estimate the expected exoplanet yields for direct imaging missions of different telescope diameters.

Kopparapu, Ravi Kumar↗
NASA NTRS1994

Sulfur dioxide in the atmosphere of Venus 1 sounding rocket observations

In this paper we present ultraviolet reflectance spectra obtained during two sounding rocket observations of Venus made during September 1988 and March 1991. We describe the sensitivity of the derived reflectance to instrument calibration and show that significant artifacts can appear in that spectrum as a result of using separate instruments to observe both the planetary radiance and the solar irradiance. We show that sulfur dioxide is the primary spectral absorber in the 190 - 230 nm region and that the range of altitudes probed by these wavelengths is very sensitive to incidence and emission angles. In a following paper Na et. al. (1994) show that sulfur monoxide features are also present in these data. Accurate identification and measurement of additional species require observations in which both the planetary radiance and the solar irradiance are measured with the same instrument. The instrument used for these observations is uniquely suited for obtaining large phase angle coverage and for studying transient atmospheric events on Venus because it can observe targets within 18 deg of the sun while earth orbiting instruments are restricted to solar elongation angles greater than or equal to 45 deg.

Mcclintock, William E.↗
NASA NTRS1994

Sulfur dioxide in the atmosphere of Venus. 1: Sounding rocket observations

In this paper we present ultraviolet reflectance spectra obtained during two sounding rocket observations of Venus made during September 1988 and March 1991. We describe the sensitivity of the derived reflectance to instrument calibration and show that significant artifacts can appear in the spectrum as a result of using separate instruments to observe both the planetary radiance and the solar irradiance. We show that sulfur dioxide is the primary special absorber in the 190-230 nm region and that the range of altitudes probed by these wavelengths is very sensitive to incidence and emission angles. In a following paper Na et al. (1994) show that sulfur monixide features are also present intese data. Accurate identification and measurement of additional species require observations in which both the planetary radiance and the solar irradiance are measured with the same instrument. The instrument used for these observations is uniquely suited for obtaining large phase angle coverage and for studying transient atmospheric events on Venus because it can observe targents within 18 deg of the Sun while Earth-orbiting instruments are restricted to solar elongation angles greater than or equal to 45 deg.

Mcclintock, William E.↗
NASA NTRS1986

Planetary spectroscopy

Infrared spectroscopic studies of the solar system in support of spacecraft investigations were researched. The studies include the physical behavior of comets, the atmospheres of the gaseous planets, and the solid surfaces of satellites and asteroids. Studies of the gaseous and solid emanations of comets using the techniques of CCD spectroscopy and imaging were focused on. An intensive observational effort was mounted, to observe comet Halley with the recently developed state of the art CCD camera system. Comet P/Giacobini-Zinner was observed. The major emphasis was placed on spectroscopy and a synoptic spectrum at least once a month was obtained. A large number of images of Halley for particular emission species and continuum regions were also obtained. The species in vestigated were: C3 (4060 A), CO+ (4505), C2 (5139), NH2 (5980), H2O+ (6185), OI (6300) and CN (9180).

Fink, U.↗
NASA NTRSDate not supplied

Low-Earth Orbit Flight Test of an Inflatable Decelerator (LOFTID) Mission Overview and Science Return

The Low-Earth Orbit (LEO) Flight Test of an Inflatable Decelerator (LOFTID) mission was the culmination of two decades of research and development led by NASA Langley Research Center for Hypersonic Inflatable Aerodynamic Decelerator (HIAD) technology. A HIAD aeroshell can be hard packed into a small volume for launch and then deployed prior to atmospheric entry for stable aerodynamic deceleration through the atmosphere. Much larger than traditional fixed diameter aeroshells that are constrained by the size of launch vehicle shrouds, inflatable decelerators create more drag and start the deceleration process in the upper reaches of the atmosphere with greater efficiency and stability. Large deployable heatshields enable spacecraft to carry bigger, heavier payloads, including scientific instruments and human support systems for planetary landing and exploration. The success of the LOFTID mission could enable new NASA missions to Mars (including access to higher altitudes than currently possible), Venus, and most solar system destinations with atmospheres, as well as cost-effective payload returns to Earth. With its unique 6m diameter inflatable heatshield, LOFTID was the first-of-a-kind orbital reentry flight, and the largest blunt body atmospheric entry of any kind. On November 10, 2022, the LOFTID aeroshell endured the harsh environments of atmospheric reentry while exhibiting stable aerodynamics through the entire spectrum of hypersonic, supersonic, transonic, and subsonic flight. The demonstration confirmed the HIAD technology structural and thermal performance as the aeroshell protected the 1100 kg Reentry Vehicle (RV) entering Earth’s atmosphere at 8 km/s, reaching Mach 30, and experiencing 9.5 g deceleration before deploying parachutes and gently splashing down in the Pacific Ocean, where it was recovered in excellent condition. The LOFTID aeroshell was exposed to an aeroheating environment representative of many Mars and LEO HIAD applications, and successfully demonstrated the ability of the heat-affected inflatable structure to withstand aerodynamic forces that exceeded those expected at Mars. This mission further demonstrated the viability of HIAD technology to deliver large payloads safely and accurately through an atmosphere via a controlled entry, descent, and landing. Whereas LOFTID was indeed a first-of-a-kind flight for an inflatable heatshield, its remarkable performance assured that it will not be the last of its kind.

J M Dinonno↗
NASA NTRSDate not supplied

Low-Earth Orbit Flight Test of an Inflatable Decelerator (LOFTID) Mission Overview and Science Return

The Low-Earth Orbit (LEO) Flight Test of an Inflatable Decelerator (LOFTID) mission was the culmination of two decades of research and development led by NASA Langley Research Center for Hypersonic Inflatable Aerodynamic Decelerator (HIAD) technology. A HIAD aeroshell can be hard packed into a small volume for launch and then deployed prior to atmospheric entry for stable aerodynamic deceleration through the atmosphere. Much larger than traditional fixed diameter aeroshells that are constrained by the size of launch vehicle shrouds, inflatable decelerators create more drag and start the deceleration process in the upper reaches of the atmosphere with greater efficiency and stability. Large deployable heatshields enable spacecraft to carry bigger, heavier payloads, including scientific instruments and human support systems for planetary landing and exploration. The success of the LOFTID mission could enable new NASA missions to Mars (including access to higher altitudes than currently possible), Venus, and most solar system destinations with atmospheres, as well as cost-effective payload returns to Earth. With its unique 6m diameter inflatable heatshield, LOFTID was the first-of-a-kind orbital reentry flight, and the largest blunt body atmospheric entry of any kind. On November 10, 2022, the LOFTID aeroshell endured the harsh environments of atmospheric reentry while exhibiting stable aerodynamics through the entire spectrum of hypersonic, supersonic, transonic, and subsonic flight. The demonstration confirmed the HIAD technology structural and thermal performance as the aeroshell protected the 1100 kg Reentry Vehicle (RV) entering Earth’s atmosphere at 8 km/s, reaching Mach 30, and experiencing 9.5 g deceleration before deploying parachutes and gently splashing down in the Pacific Ocean, where it was recovered in excellent condition. The LOFTID aeroshell was exposed to an aeroheating environment representative of many Mars and LEO HIAD applications, and successfully demonstrated the ability of the heat-affected inflatable structure to withstand aerodynamic forces that exceeded those expected at Mars. This mission further demonstrated the viability of HIAD technology to deliver large payloads safely and accurately through an atmosphere via a controlled entry, descent, and landing. Whereas LOFTID was indeed a first-of-a-kind flight for an inflatable heatshield, its remarkable performance assured that it will not be the last of its kind.

John M DiNonno↗
NASA NTRS1985

Water loss from Venus: Implications for the Earth's early atmosphere

The atmosphere of Venus outgassed rapidly as a result of planetary heating during accretion, resulting in massive water loss. The processes affecting atmospheric chemistry following accretion have consisted largely of hydrogen escape and internal re-equilibrium. The initial bulk composition of Venus and Earth are assumed to have been roughly similar. Chemical speciation on Venus was controlled by the temperature and oxygen buffering capacity of the surface magma. It is also assumed that the surfaces of planetary bodies of the inner solar system were partly or wholly molten during accretion with a temperature estimated at 1273 to 1573 K. To investigate the range of reasonable initial atmospheric compositions on Venus, limits have to be set for the proportion of total hydrogen and the buffered fugacity of oxygen. Using the C/H ratio of 0.033 set for Earth, virtually all of the water generated during outgassing must later have been lost in order to bring the current CO2/H2O ratio for Venus up to its observed value of 10 sup 4 to 10 sup 5. The proportion of H2O decreases in model atmospheres with successfully higher C/H values, ultimately approaching the depleted values currently observed on Venus. Increasing C/H also results in a rapid increase in CO/H2O and provides an efficient mechanism for water loss by the reaction CO+H2O = CO2 + H2. This reaction, plus water loss mechanisms involving crustal iron, could have removed a very large volume of water from the Venusian atmosphere, even at a low C/H value.

Richardson, S. M.↗
NASA NTRS1993

Low-energy ion implantation: Large mass fractionation of argon

The isotropic signatures of noble gases in the atmospheres of the Earth and other planets are considerably evolved when compared to signatures observed in the solar wind. The mechanisms driving the evolution of planetary volatiles from original compositions in the solar accretion disk are currently poorly understood. Modeling of noble-gas compositional histories requires knowledge of fractionating processes that may have operated through the evolutionary stages. Since these gases are chemically inert, information on noble-gas fractionation processes can be used as probes. The importance of understanding these processes extends well beyond 'noble-gas planetology.' Trapped argon acquired by low-energy implantation (approximately less than 100 eV) into solids is strongly mass fractionated (approximately greater than or equal to 3 percent/amu). This has potential implications for the origin and evolution of terrestrial planet atmospheres.

Ponganis, K. V.↗
NASA NTRS2012

Entry, Descent, and Landing With Propulsive Deceleration

The future exploration of the Solar System will require innovations in transportation and the use of entry, descent, and landing (EDL) systems at many planetary landing sites. The cost of space missions has always been prohibitive, and using the natural planetary and planet s moons atmospheres for entry, descent, and landing can reduce the cost, mass, and complexity of these missions. This paper will describe some of the EDL ideas for planetary entry and survey the overall technologies for EDL that may be attractive for future Solar System missions.

Palaszewski, Bryan↗
NASA NTRS1987

The rotation rate of Uranus, its internal structure, and the process of planetary accretion

It is investigated whether Uranus models with higher values of the total planetary ice to rock ratio (I/R) can be made consistent with the rotation period of 17.24 hr. measured by Voyager 2, and with the 16-pole moment of the gravitational field (J4) derived from the observations of French et al. (1986). An atmospheric enhancement of H2O, NH3, and CH4 of not more than about 30 times the solar value, and an I/R value of greater than 16, are implied by these models. A planetary accretion scenario whereby such I/R values are possible for a large range of planetesimal radii and initial velocities is discussed.

Podolak, M.↗
NASA NTRS1972

Proceedings of the Space Shuttle Sortie Workshop. Volume 2: Working group reports

Details are presented on the mission planning progress in each of the working paper reports. The general topics covered are the following: space technology; materials processing and space manufacturing; communications and navigation; earth and ocean physics; oceanography; earth resources and surface environmental quality; meteorology and atmospheric environmental quality; life sciences; atmospheric and space physics; solar physics; high energy cosmic rays; X-ray and gamma ray astronomy; ultraviolet-optical astronomy; planetary astronomy; and infrared astronomy.

Source record↗
NASA NTRS1980

Outer satellite atmospheres: Their extended nature and planetary interactions

Highly developed numerical models are applied to interpret extended-atmosphere data for the sodium cloud of Io and the hydrogen torus of Titan. Solar radiation pressure was identified and verified by model calculations as the mechanism to explain two different east-west asymmetries observed in the sodium cloud. Analysis of sodium line profile data, suggesting that a Jupiter magnetospheric wind may be responsible for high speed sodium atoms emitted from Io, and preliminary modeling of the interaction of the Io plasma torus and Io's sodium cloud are also reported. Models presented for Titan's hydrogen torus are consistent both with the recent Pioneer 11 measurements and earlier Earth-orbiting observations by the Copernicus satellite. Progress is reported on developing models for extended gas and dust atmospheres of comets.

Smyth, W. H.↗
NASA NTRS1989

Climate evolution on the terrestrial planets

The present comparative evaluation of the long-term evolution of the Venus, earth, and Mars climates suggests that the earth's climate has remained temperate over most of its history despite a secular solar luminosity increase in virtue of a negative-feedback cycle based on atmospheric CO2 levels and climate. The examination of planetary climate histories suggests that an earth-sized planet should be able to maintain liquid water on its surface at orbital distances in the 0.9-1.5 AU range, comparable to the orbit of Mars; this, in turn, implies that there may be many other habitable planets within the Galaxy.

Kasting, J. F.↗
NASA NTRS1993

Constraints on N2 in Neptune's atmosphere from Voyager measurements

It is shown that N2 may be present in the troposphere of Neptune in an amount difficult to evaluate but which could easily be as high as 0.003, while there is no evidence that it is present in the atmosphere of Uranus. The estimate of the helium abundance depends on the assumed value for N2. If there is no N2 in the observed region of the atmosphere of Uranus and an N2 mole fraction of 0.003 on Neptune, the central value of the estimates of the helium abundance are equal to 0.26 by mass in both planets, which is close to the protosolar value of 0.28. This would imply that the He/H2 ratios measured in the outer atmospheres of Uranus and Neptune are representative of the ratio in the primitive solar nebula and thus were not modified during planetary formation.

Conrath, B. J.↗
NASA NTRS2002

Solar Flight on Mars and Venus

Solar powered aircraft are of interest for exploring both Mars and Venus. The thin atmosphere of Mars presents a difficult environment for flying. It is clear that a new approach is needed. By making a totally solar airplane, we can eliminate many of the heavy components, and make an airplane that can fly without fuel. Using high efficiency solar cells, we can succeed with an airplane design that can fly for up to 6 hours in near-equatorial regions of Mars (4 hours of level flight, plus two hours of slow descent), and potentially fly for many days in the polar regions. By designing an airplane for a single day flight. In particular, this change means that we no longer have to cope with the weight of the energy storage system that made previous solar powered airplanes for Mars impractical). The new airplane concept is designed to fly only under the optimal conditions: near equatorial flight, at the subsolar point, near noon. We baseline an 8 kg airplane, with 2 kg margin. Science instruments will be selected with the primary criterion of low mass. Solar-powered aircraft are also quite interesting for the exploration of Venus. Venus provides several advantages for flying a solar-powered aircraft. At the top of the cloud level, the solar intensity is comparable to or greater than terrestrial solar intensities. The atmospheric pressure makes flight much easier than on planets such as Mars. The atmospheric pressure on Venus is presented. From an altitude of approximately 45 km (pressure = 2 bar), to approximately 60 km (pressure = 0.2 bar), terrestrial airplane experience can be easily applied to a Venus airplane design. At these flight altitudes, the temperature varies from 80 C at 45 km, decreasing to -35 C at 60 km. Also, the slow rotation of Venus allows an airplane to be designed for flight within continuous sunlight, eliminating the need for energy storage for nighttime flight. These factors make Venus a prime choice for a long-duration solar-powered aircraft. Fleets of solar-powered aircraft could provide an architecture for efficient and low-cost comprehensive coverage for a variety of scientific missions. Exploratory planetary mapping and atmospheric sampling can lead to a greater understanding of the greenhouse effect not only on Venus but on Earth as well.

Landis, Geoffrey A.↗
NASA NTRS2018

Modeling Clouds in Brown Dwarf and Exoplanet Giant Planet Atmospheres

Clouds and hazes are commonplace in the atmospheres of solar system planets and are likely ubiquitous in the atmospheres of extrasolar planets as well. Clouds affect every aspect of a planetary atmosphere, from the transport of radiation, to atmospheric chemistry, to dynamics and they influence - if not control - aspects such as surface temperature and habitability. In my presentations I aim to provide an introduction to the role and properties of clouds in exoplanetary atmospheres and will discuss the lessons learned from the past two decades of studying clouds in brown dwarf atmospheres. I will consider the role clouds play in influencing the spectra of extrasolar giant planets and will discuss the relative simple approaches that have been taken so far to model exoplanet clouds. I will also review how the scattering and extinction efficiencies of cloud particles may be approximated in certain limiting cases of small and large particles in order to facilitate physical understanding and will discuss the need for optimized cloud models that can be applied to exoplanet transmission spectra. Finally I will discuss the various sources of aerosol opacity, including photochemistry, disequilibrium chemistry, and equilibrium condensation.

Marley, Mark S.↗