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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 523 records · Page 29
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

Future observations of planetary rings from groundbased observatories and earth-orbiting satellites

Three of the outer planets of our solar system are known to possess ring systems and, among the three known systems, all have one or more components that are detectable from the vicinity of the earth. Among the more promising methods for continuing study are direct imaging and occultations, obtainable both from the ground and from earth-orbiting facilities such as Space Telescope. Relevant future observations made from the vicinity of earth are expected to provide new knowledge of the dynamical and photometric properties of these outer solar system planetary rings.

Smith, B. A.↗
NASA NTRS2004

Fractal Variation with Changing Line Length: A Potential Problem for Planetary Lava Flow Identification

Fractals are objects that are generally self similar at all scales. Coastlines, mountains, river systems, planetary orbits and some mathematical objects are all examples of fractals. Bruno et al. used the structured walk model of Richardson to establish that lava flows are fractals and that lava flow morphology could be determined by looking at the fractal dimension of flow margins. They determined that Hawaiian a.a flows have fractal dimensions that range from 1.05 to 1.09 and that the pahoehoe lava flows have a fractal dimension from 1.13 to 1.23. We have analyzed a number of natural and simulated lava flow margins and find that the fractal dimension varies according to the number and length of rod lengths used in the structured walk method. The potential variation we find in our analyses is sufficiently large so that unambiguous determination of lava flow morphology is problematic for some flows. We suggest that the structured walk method can provide meaningful fractal dimensions if rod lengths employed in the analysis provide a best-fit residual of greater than 0.98, as opposed to the 0.95 cutoff used in previous studies. We also find that the use of more than 4 rod lengths per analysis also reduces ambiguity in the results.

Hudson, Richard K.↗
DOE OSTI2021

A Multiwavelength Look at the GJ 9827 System: No Evidence of Extended Atmospheres in GJ 9827b and d from HST and CARMENES Data

GJ 9827 is a bright star hosting a planetary system with three transiting planets. As a multiplanet system with planets that sprawl within the boundaries of the radius gap between terrestrial and gaseous planets, GJ 9827 is an optimal target to study the evolution of the atmospheres of close-in planets with a common evolutionary history and their dependence from stellar irradiation. Here we report on the Hubble Space Telescope (HST) and CARMENES transit observations of GJ 9827 planets b and d. We performed a stellar and ISM characterization from the ultraviolet HST spectra, obtaining fluxes for Lyα and Mg ii of F(Lyα) = (5.42{sub −0.75}{sup +0.96}) × 10{sup −13} erg cm{sup −2} s{sup −1} and F(Mgii) = (5.64 ± 0.24) × 10{sup −14} erg cm{sup −2} s{sup −1}. We also investigated a possible absorption signature in Lyα in the atmosphere of GJ 9827b during a transit event from HST spectra, as well as Hα and He i signature for the atmosphere of GJ 9827b and d from CARMENES spectra. We found no evidence of an extended atmosphere in either of the planets. This result is also supported by our analytical estimations of mass loss based on the measured radiation fields for all three planets of this system, which led to a mass-loss rate of 0.4, 0.3, and 0.1 planetary masses per Gyr for GJ 9827b, c, and d, respectively. These values indicate that the planets could have lost their volatiles quickly in their evolution and probably do not retain an atmosphere at the current stage.

47 OTHER INSTRUMENTATION↗
NASA NTRS2014

Multi-Mission System Analysis for Planetary Entry (M-SAPE) Version 1

This report describes an integrated system for Multi-mission System Analysis for Planetary Entry (M-SAPE). The system in its current form is capable of performing system analysis and design for an Earth entry vehicle suitable for sample return missions. The system includes geometry, mass sizing, impact analysis, structural analysis, flight mechanics, TPS, and a web portal for user access. The report includes details of M-SAPE modules and provides sample results. Current M-SAPE vehicle design concept is based on Mars sample return (MSR) Earth entry vehicle design, which is driven by minimizing risk associated with sample containment (no parachute and passive aerodynamic stability). By M-SAPE exploiting a common design concept, any sample return mission, particularly MSR, will benefit from significant risk and development cost reductions. The design provides a platform by which technologies and design elements can be evaluated rapidly prior to any costly investment commitment.

Samareh, Jamshid↗
DOE OSTI2020

The Discovery of the Long-Period, Eccentric Planet Kepler-88 d and System Characterization with Radial Velocities and Photodynamical Analysis

We present the discovery of Kepler-88 d (P{sub d} = 1403±14 days, Msini{sub d}=965±44 M{sub ⊕}=3.04±0.13 M{sub J}, e{sub d}=0.41±0.03) based on six years of radial velocity (RV) follow-up from the W. M. Keck Observatory High Resolution Echelle Spectrometer spectrograph. Kepler-88 has two previously identified planets. Kepler-88 b (KOI-142.01) transits in the NASA Kepler photometry and has very large transit timing variations (TTVs). Nesvorný et al. performed a dynamical analysis of the TTVs to uniquely identify the orbital period and mass of the perturbing planet (Kepler-88 c), which was later was confirmed with RVs from the Observatoire de Haute-Provence (OHP). To fully explore the architecture of this system, we performed photodynamical modeling on the Kepler photometry combined with the RVs from Keck and OHP and stellar parameters from spectroscopy and Gaia. Planet d is not detectable in the photometry, and long-baseline RVs are needed to ascertain its presence. A photodynamical model simultaneously optimized to fit the RVs and Kepler photometry yields the most precise planet masses and orbital properties yet for b and c: P{sub b}=10.91647±0.00014 days, M{sub b}=9.5±1.2 M{sub ⊕}, P{sub c}=22.2649±0.0007 days, and M{sub c}=214.0±5.3 M{sub ⊕}. The photodynamical solution also finds that planets b and c have low eccentricites and low mutual inclination, are apsidally anti-aligned, and have conjunctions on the same hemisphere of the star. Continued RV follow-up of systems with small planets will improve our understanding of the link between inner planetary system architectures and giant planets.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

TESS Hunt for Young and Maturing Exoplanets (THYME). III. A Two-planet System in the 400 Myr Ursa Major Group

Exoplanets can evolve significantly between birth and maturity, as their atmospheres, orbits, and structures are shaped by their environment. Young planets (<1 Gyr) offer an opportunity to probe the critical early stages of this evolution, where planets evolve the fastest. However, most of the known young planets orbit prohibitively faint stars. We present the discovery of two planets transiting HD 63433 (TOI 1726, TIC 130181866), a young Sun-like (M{sub ∗}=0.99±0.03) star. Through kinematics, lithium abundance, and rotation, we confirm that HD 63433 is a member of the Ursa Major moving group (τ = 414 ± 23 Myr). Based on the TESS light curve and updated stellar parameters, we estimate that the planet radii are 2.15 ± 0.10 R {sub ⊕} and 2.67 ± 0.12 R {sub ⊕}, the orbital periods are 7.11 and 20.55 days, and the orbital eccentricities are lower than about 0.2. Using High Accuracy Radial velocity Planet Searcher for the Northern hemisphere velocities, we measure the Rossiter–McLaughlin signal of the inner planet, demonstrating that the orbit is prograde. Since the host star is bright (V = 6.9), both planets are amenable to transmission spectroscopy, radial velocity measurements of their masses, and more precise determination of the stellar obliquity. This system is therefore poised to play an important role in our understanding of planetary system evolution in the first billion years after formation.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1980

Prospects for very deep space optical communication using photon-counting links

An investigation is conducted regarding the feasibility to use an optical communication system in connection with space missions involving a study of stars and, possibly, planetary systems in the vicinity of the solar system. A possible candidate for the considered kind of mission would be Barnard's Star, at six light years distance. Pierce et al. (1981), have shown that the capacity of a photon-counting link in the presence of thermal noise at low temperature is essentially the same as for microwave. The conducted investigation assumes the employment of a pulse position modulation scheme limited by technology to approximately 1,000,000 positions. The use of an optical communication system similar to the considered type is found to be very likely for the contemplated kind of space mission.

Posner, E. C.↗
NASA NTRS1989

Comparison study of gear dynamic computer programs at NASA Lewis Research Center

A comparison study was performed on four gear dynamic analysis computer programs developed under NASA/Army sponsorship. These programs are GRDYNMULT (a multimesh program applicable to a number of epicyclic systems), TELSGE (a single mesh program), PGT (a multimesh program applicable to a planetary system with three planets), and DANST (a single mesh program). The capabilities and features, input and output options, and technical aspects of the programs were reviewed and compared. Results are presented in a concise tabular form. Parametric studies of the program models were performed to investigate the predicted results of the programs as input parameters such as speed, torque, and mesh damping were varied. In general, the program models predicted similar dynamic load and stress levels as operating conditions were varied. Flash temperature predictions from programs GRDYNMULT and TELSGE indicated similar trends; however, actual values were not in close agreement. The program GRDYNMULT was found to be the most versatile in system size, type, and analysis capabilities. The programs DANST, TELSGE, and PGT are more specialized for specific systems; however, in specific areas they provide a more detailed treatment than GRDYNMULT.

Zakrajsek, James J.↗
NASA NTRS1991

The Astrometric Imaging Telescope - A space-based observatory for extra-solar planet detection

The paper describes the objectives, techniques, instrumentation, and mission of the planned Astrometric Imaging Telescope. This space-based observatory is designed to detect and characterize extra-solar planetary systems. Results will contribute to the understanding of the astrophysics of stellar and planetary formation and provide an impetus for the study of exobiology.

Pravdo, Steven H.↗
NASA NTRS1992

Perspectives from space: NASA classroom information and activities

This booklet contains the information and classroom activities included on the backs of the eight poster series, 'Perspectives From Space'. The first series, Earth, An Integrated System, contains information on global ecology, remote sensing from space, data products, earth modeling, and international environmental treaties. The second series, Patterns Among Planets, contains information on the solar system, planetary processes, impacts and atmospheres, and a classroom activity on Jupiter's satellite system. The third series, Our Place In The Cosmos, contains information on the scale of the universe, origins of the universe, mission to the universe, and three classroom activities. The fourth series, Our Sun, The Nearest Star, contains information on the Sun. The fifth series, Oasis Of Life, contains information on the development of life, chemical and biological evolution on Earth and the search for other life in the universe. The sixth series, The Influence Of Gravity, contains information on Newton's Law of Gravity, space and microgravity, microgravity environment, and classroom activities on gravity. The seventh series, The Spirit Of Exploration, contains information on space exploration, the Apollo Program, future exploration activities, and two classroom activities. The eighth series, Global Cooperation, contains information on rocketry, the space race, and multi-nation exploration projects.

Source record↗
NASA NTRS2002

Organic Synthesis in Space

This talk will review our current understanding of the synthesis of organic molecules in space, with particular emphasis on the synthesis of those compounds that may be of prebiotic interest. The talk will address the possibility that molecules created in the interstellar medium may play a role in the origin and evolution of life on planetary surfaces. The various organic and volatile compounds that are now known or suspected to exist in a variety of space environments (stellar outflows, the diffuse interstellar medium, dense molecular clouds, protostellar nebulae, and planetesimal parent bodies in planetary systems) will be reviewed. This information comes largely from the combined applications of observational infrared and radio spectroscopy, laboratory astrophysical simulations, and theoretical astrochemistry. This will be followed by a discussion of the evidence, largely gathered from the laboratory isotopic study of extraterrestrial materials (meteorites and cosmic dust), that interstellar materials, including organics, can and do survive the transition from the interstellar space into forming stellar systems. Once there, some of this material can be delivered largely unaltered to planetary surfaces where it can play key roles in the origin and subsequent evolution of life.

Sandford, Scott A.↗
NASA NTRS2008

Jupiter System Observer

This slide presentation reviews the scientific philosophy that is guiding the planning behind the Jupiter System Observer (JSO). The JSO would be a long-term platform for studying Jupiter and the complete Jovian system. The goal is to advance the understanding of the fundamental processes of planetary systems, their formation and evolution.

Jupiter↗
NASA NTRS1994

The Astrometric Imaging Telescope Optical System

This oral presentation describes the Astrometric Imaging Telescope as a space-based observatory designed to detect and study planetary systems and circumstellar material around hundreds of nearby stars.

N/A↗
NASA NTRS1993

Exploring planetary worlds

A review of the planetary system is presented from a uniform perspective, taking advantage of the data obtained during the planetary space missions. A comparative approach is used, which makes it possible to consider each planet or a satellite in context, focusing both on their common origin and on the processes that have influenced their evolution. The discussion focuses on the Jovian planets, the moon and the Mercury, Venus and Earth, and small bodies in the outer solar system. Attention is also given to comets, asteroids, and cosmic impacts.

Morrison, David↗
DOE OSTI2021

Planet Occurrence Rate Correlated to Stellar Dynamical History: Evidence from Kepler and Gaia

The dynamical history of stars influences the formation and evolution of planets significantly. To explore the influence of dynamical history on the planet formation and evolution using observations, we assume stars that experienced significantly different dynamical histories tend to have different relative velocities. Utilizing the accurate Gaia–Kepler Stellar Properties Catalog, we select single main-sequence stars and divide these stars into three groups according to their relative velocities, i.e., high-V, medium-V, and low-V stars. After considering the known biases from Kepler data and adopting prior and posterior correction to minimize the influence of stellar properties on planet occurrence rate, we find that high-V stars have a lower occurrence rate of super-Earths and sub-Neptunes (1–4 R {sub ⊕}, P < 100 days) and a higher occurrence rate of sub-Earth (0.5–1 R {sub ⊕}, P < 30 days) than low-V stars. Additionally, high-V stars have a lower occurrence rate of hot Jupiter-sized planets (4–20 R {sub ⊕}, P < 10 days) and a slightly higher occurrence rate of warm or cold Jupiter-sized planets (4–20 R {sub ⊕}, 10 < P < 400 days). After investigating multiplicity and eccentricity, we find that high-V planet hosts prefer a higher fraction of multiplanet systems and lower average eccentricity, which are consistent with the eccentricity–multiplicity dichotomy of Kepler planetary systems. All of these statistical results favor the scenario that high-V stars with large relative velocity may experience fewer gravitational events, while low-V stars may be influenced by stellar clustering significantly.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1993

The Population of the Trans-Neptunian Region

The Pluto-Charon system orbits the Sun in the trans-Neptunian region, at the edge of the planetary system. Because of its location and relatively small mass, the Pluto-Charon binary is not capable of dynamically clearing its orbital zone of smaller objects. Thus, this zone is shared with two major cometary reservoirs, the Oort cloud and the Kuiper belt. This trans-Neptunian region environment is described.

Pluto Charon Oort Cloud Kuiper Belt Trans-Neptunia↗
NASA NTRS2009

The Herschel DUNES Open Time Key Programme

We will use the unique photometric capabilities provided by Herschel to perform a deep and systematic survey for faint, cold debris disks around nearby stars. Our sensitivity-limited Open Time Key Programme (OTKP) aims at finding and characterizing faint extrasolar analogues to the Edgeworth-Kuiper Belt (EKB) in an unbiased, statistically significant sample of nearby FGK main-sequence stars. Our target set spans a broad range of stellar ages (from 0.1 to 10 Gyr) and is volume-limited (distances < 20 pc). All stars with known extrasolar planets within this distance are included; additionally, some M- and A-type stars will be observed in collaboration with the Herschel DEBRIS OTKP, so that the entire sample covers a decade in stellar mass, from 0.2 to 2 solar masses. We will perform PACS and SPIRE photometric observations covering the wavelength range from 70 to 500 microns. The PACS observations at 100 microns have been designed to detect the stellar photospheres down to the confusion limit with a signal-to-noise ratio > 5. The observations in the other Herschel bands will allow us to characterize, model, and constrain the disks. As a result, it will be possible for us to reach fractional dust luminosities of a few times 10-7, close to the EKB level in the Solar System. This will provide an unprecedented lower limit to the fractional abundance of planetesimal systems and allow us to assess the presence of giant planets, which would play dynamical roles similar to those played by Jupiter and Neptune in the Solar System. The proposed observations will provide new and unique evidence for the presence of mature planetary systems in the solar neighbourhood and, in turn, will address the universality of planet/planetary system formation in disks around young stars.

Danchi, William C.↗
NASA NTRS1993

The Detection and Study of Pre-Planetary Disks

A variety of evidence suggests that at least 50% of low-mass stars are surrounded by disks of the gas and dust similar to the nebula that surrounded the Sun, before the formation of the planets. The properties of these disks may bear strongly on the way in which planetary systems form and evolve.

Pre-Planetary↗