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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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NASA NTRS1977

Geology of the Valles Marineris - First Analysis of Imaging from the Viking 1 Orbiter Primary Mission

The Valles Marineris on the planet Mars constitute an enormous group of steep-walled equatorial canyons extending over an area more than 4000 km long and up to 700 km wide. An overview of Valles Marineris is provided, taking into account canyon system subdivisions, imaging and topographic data, Noctis Labyrinthus, western troughs, central troughs, east central troughs, and eastern canyons. Aspects of canyon wall and canyon floor morphology are discussed, giving attention to erosional features, layered rocks in canyon walls, tectonic features, plains, landslide deposits, hilly terrain, fractured floor, and floor plateaus and ridges. Upland pits and closed depressions in the canyons are considered along with regional tectonics and regional erosional styles.

Blasius, K. R.↗

NASA NTRS1986

Some properties of trans-equatorial ion whistlers observed by Isis satellites during geomagnetic storms

Several ion whistlers were observed by the polar orbiting satellites, Isis, during geomagnetic storms associated with large solar flares in 1982. It seems that the proton density ratio to the total ions deduced from the crossover frequency of the transequatorial ion whistlers observed at geomagnetic low latitudes during the main phase of the geomagnetic storm on July 14, 1982 was lower than the usual density ratio. An anomalous pattern seen on the time-compressed dynamic spectra of the ion whistlers on September 6, 1982 may suggest the existence of effects by the component He(3+) in a quite small amount.

Watanabe, S.↗

NASA NTRS2007

Equatorial Enhancement of the Nighttime OH Mesospheric Infrared Airglow

Global measurements of the hydroxyl mesospheric airglow over an extended period of time have been made possible by the NASA SABER infrared sensor aboard the TIMED satellite which has been functioning since December of 2001. The orbital mission has continued over a significant portion of a solar cycle. Experimental data from SABER for several years have exhibited equatorial enhancements of the nighttime mesospheric OH (delta v = 2) airglow layer consistent with the high average diurnal solar flux. The brightening of the OH airglow typically means more H + O3 is being reacted. At both the spring and autumn seasonal equinoxes when the equatorial solar UV irradiance mean is greatest, the peak volume emission rate (VER) of the nighttime Meinel infrared airglow typically appears to be both significantly brighter plus lower in altitude by several kilometres at low latitudes compared with midlatitude findings.

Baker, D. J.↗

NASA NTRS1974

The Saturnian 'gas-doughnut' hypothesis

It is hypothesized that constituents escaping the atmosphere of Titan are unlikely to have sufficient velocity to escape from Saturn. Thus most of the material will enter into elliptical orbits which, at some point, cross Titan's orbit at a small angle. In total, this matter will form a 'doughnut' shaped feature, roughly centered on Titan's orbit and having dimensions of about 20 Saturn radii in the Saturnian-equatorial plane and 10 Saturn radii normal to this plane. It is assumed that the material is lost from the doughnut when it is ionized or is recaptured by Titan's atmosphere. The upper limit on the density of hydrogen in the ring is estimated to be about 1,000 particles per cu cm, with up to 99% of the particles in the doughnut being recaptured by Titan.

Mcdonough, T. R.↗

NASA NTRS1984

Io's sodium directional features - Evidence for a magnetospheric-wind-driven gas escape mechanism

Elongated features in Io's sodium cloud, directed away from Jupiter and inclined both to the north and to the south of the satellite's orbital plane, have been observed. The north/south directions of the features are correlated with Io's magnetic longitude, suggesting a formation mechanism involving the oscillating plasma torus. It is shown by means of a model analysis that the features can result from a source of high-velocity (about 20 km/s) sodium combined with the oscillating neutral sodium sink provided by the plasma. The phase relationship between the features' directions and Io's magnetic longitude can be understood if escaping sodium is initially directed at near right angles to Io's orbital motion. The directionality of the features requires that the sodium flux from equatorial regions be higher than that from the poles. The initial directions and speeds of sodium atoms escaping Io to form the directional features can be understood in terms of a magnetospheric-wind-driven escape mechanism. The one sequence of directional feature observations that has been analyzed in detail implies a high-speed sodium source rate of about 10 to the 26th atoms/s.

Pilcher, C. B.↗

NASA NTRS1986

Local variation of haze thickness on the equatorial region of Venus

The horizontal distribution of haze particles in the equatorial region of Venus was investigated using selected polarimetry maps obtained by the Orbiter Cloud Photopolarimeter (OCP) aboard the Pioneer Venus Orbiter, with five of these maps having been acquired on five consecutive terrestrial days. Nine sets of OCP polarimetry maps (PM) similar to PM 16 employed by Kawabata et al. (1980) were selected, and 935 nm data points were extracted to construct a cloud-haze model, from which the haze fraction f(h) within the cloud and the corresponding optical thickness tau(h) were determined for the period from December 1978 to October 1980. The results indicate that, in this period, the upper cloud layer of Venus had haze layers with tau(h) of about 0.02. Furthermore, the submicron particles present within the principal cloud contributed approximately 6 percent to the total scattering cross section per unit volume. Although no systematic time variations in the derived values of tau(h) and f(h) were noticeable, the consecutive five day observations indicated a presence of a large-scale horizontal inhomogeneity in haze particle distribution.

Kawabata, Kiyoshi↗

NASA NTRS1991

Arecibo S-band radar program

The high powered 12.6 cm wavelength radar on the 1000 ft Arecibo reflector is used for a variety of studies of solar system bodies. These include: (1) the radar mapping of the surfaces of Mercury, Venus, the moon and Mars in both senses (usually the two circulars) of received polarization; (2) high time resolution ranging measurements to Mercury and Mars to obtain height profiles and scattering parameters in the equatorial region and to test relativistic and gravitational theories; (3) measurements of the orbital parameters, scattering properties, figure and spin vectors of asteroids and comets; and (4) observations of the satellites of Mars, Phobos and Deimos, and the Galilean satellites of Jupiter.

Campbell, Donald B.↗

NASA NTRS2003

Observations of the Geopause at the Equatorial Magnetopause: Density and Temperature

Magnetic flux tubes containing plasmaspheric ion density and composition have been observed in the region between the classical plasmapause and the magnetopause. New observations show that these ion distributions exist at the equatorial, post-noon magnetopause. Comparison to observations of similar distributions at geosynchronous orbit and to simulations leads to the conclusion that these ions are convected from these regions to the magnetopause. This represents an extension of the geopause to the outer edge of the magnetosphere on the dayside. The presence of ion densities > 10 cu cm in this region must have profound impact on the nature of plasma processes that occur there.

Chandler, M. O.↗

NASA NTRS2017

Optical Navigation Simulation and Performance Analysis for Osiris-Rex Proximity Operations

The OSIRIS-REx mission timeline with OpNav milestones is presented in Figure 1. The first three proximity operations (ProxOps) mission phases focus on Navigation. During these phases, OSIRIS-REx approaches Bennu, conducts equatorial and polar flybys in Preliminary Survey, and inserts into the first mission orbit: Orbit A. During these phases, the OpNav techniques evolve from point-source to resolved-body centroiding to landmark tracking.

Jackman, Coralie D.↗

DOE OSTI2021

Strain-Induced Anion-Site Occupancy in Perovskite Oxyfluoride Films

Anion ordering is a promising route to engineer physical properties in functional heteroanionic materials. A central challenge in the study of anion-ordered compounds lies in developing robust synthetic strategies to control anion occupation and in understanding the resultant implications for electronic structure. Here, we show that epitaxial strain induces preferential occupation of F and O on the anion sites in perovskite oxyfluorides SrMn O2.5-δ F γ films grown on different substrates. Under compressive strain, F tends to occupy the apical-like sites, which was revealed by F and O K-edge linearly polarized x-ray absorption spectroscopy and density functional theory calculations, resulting in an enhanced c-axis expansion. Under tensile strain, F tends to occupy the equatorial-like sites, enabling the longer Mn-F bonds to lie within the plane. The oxyfluoride films exhibit a significant orbital polarization of the 3d electrons, distinct F-site dependence to their valence band density of states, and an enhanced resistivity when F occupies the apical-like anion site compared to the equatorial-like site. By demonstrating a general strategy for inducing preferential anion-site occupancy in oxyfluoride perovskites, this work lays the foundation for future materials design and synthesis efforts that leverage this greater degree of atomic control to realize new polar or quasi-two-dimensional materials.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

NASA NTRS2000

Martian North Polar Water-Ice Clouds During the Viking Era

The Viking Orbiters determined that the surface of Mars' northern residual cap consists of water ice. Observed atmospheric water vapor abundances in the equatorial regions have been related to seasonal exchange between reservoirs such as the polar caps, the regolith and between different phases in the atmosphere. Kahn modeled the physical characteristics of ice hazes seen in Viking Orbiter imaging limb data, hypothesizing that ice hazes provide a method for scavenging water vapor from the atmosphere and accumulating it into ice particles. Given that Jakosky found that these particles had sizes such that fallout times were of order one Martian sol, these water-ice hazes provided a method for returning more water to the regolith than that provided by adsorption alone. These hazes could also explain the rapid hemispheric decrease in atmospheric water in late northern summer as well as the increase during the following early spring. A similar comparison of water vapor abundance versus polar cap brightness has been done for the north polar region. They have shown that water vapor decreases steadily between L(sub s) = 100-150 deg while polar cap albedo increases during the same time frame. As a result, they suggested that late summer water-ice deposition onto the ice cap may be the cause of the cap brightening. This deposition could be due to adsorption directly onto the cap surface or to snowfall. Thus, an examination of north polar waterice clouds could lend insight into the fate of the water vapor during this time period. Additional information is contained in the original extended abstract.

Tamppari, L. K.↗

NASA NTRS2009

HAT-P-7: A Retrograde or Polar Orbit, and a Third Body

We showed that the exoplanet HAT-P-7b has an extremely tilted orbit, with a true angle of at least 86 degrees with respect to its parent star's equatorial plane, and a strong possibility of retrograde motion. We also report evidence for an additional planet or companion star. The Rossiter-McLaughlin effect was found to be a blueshift during the first half of the transit and a redshift during the second half, an inversion of the usual pattern, implying that the angle between the sky-projected orbital and stellar angular momentum vectors is 182.5 plus or minus 9.4 degrees. The third body is implicated by excess RV variation of the host star over 2 yr. Some possible explanations for the tilted orbit of HAT-P-7b are a close encounter with another planet, the Kozai effect, and resonant capture by an inward-migrating outer planet.

Winn, Joshua N.↗

NASA NTRS1981

VLF-emissions associated with ring current electrons - Off-equatorial observations

Simultaneous observations of magnetospheric VLF emissions and the associated enhancement of ring current electrons up to 15 deg geomagnetic latitudes are made by the Explorer 45. Using a 4 deg inclination of orbit with a tilt angle of the earth's magnetic dipole axis of 11 deg, microdensitometer scanning of wideband data indicates that the band of missing emissions in the off-equatorial whistler mode emissions appears at f(H0)/2. Intensities above f(H0)/2 appear very weak in contrast to those of near-equatorial emissions where f(H0) is the equatorial electron gyrofrequency corresponding to the local gyrofrequency at the satellite. Whistler mode waves are reflected from high latitudes to the equator inside the source region, and the intensities of those waves are shown to be insufficient to explain the observed emissions below f(H0)/2 at the equator. Results indicate that the superposition of two types of emissions from the same processes at different locations is not the main mechanism for the formation of the two-band chorus, and the dominant sources of these choruses are located at the + or - 5 deg geomagnetic latitude.

Maeda, K.↗

NASA NTRS2006

Solar Wind Excitation of Pc5 Fluctuations in the Magnetosphere and on the Ground

The primary purpose of this paper is to show the strong link between solar wind compressional fluctuations in the 1-8 mHz frequency range and Pc5 fluctuations in the magnetosphere near the magnetopause, at geosynchronous orbit, over the poles, and on the ground. We focus on a time interval in March and April 2002 when there was a favorable alignment of satellites combined with ten high speed solar wind streams. We used the S3C Great Observatory: specifically, ACE and Wind in the solar wind, Geotail near the magnetopause, GOES 8 and 10 at geosynchronous orbit, Cluster over the poles, and CANOPUS/CARISMA ground stations near the footpoints of magnetic field lines connected to either the magnetopause or the GOES satellites. Using four examples and a statistical survey we show that magnetospheric Pc5 fluctuations exist regardless of IMF orientation and for a wide range of speeds and dynamic pressures; the amplitude and power of magnetospheric fluctuations depends primarily on the amplitude and power of solar wind dynamic pressure fluctuations. The driving and response frequency of these geoeffective fluctuations is in the range 0.5 - 4 mHz. The most striking magnetospheric response occurs when the solar wind speed, dynamic pressure, and dynamic pressure fluctuations all increase at approximately the same time, as frequently occurs near the leading edge of high speed streams. We show evidence of oscillating Poynting Flux at the magnetopause determined using Geotail data that both excites a FLR and propagates evanescently inward. These observations suggest that, at least for this time interval at spring equinox, the entry path is from the dayside equatorial magnetopause inward; multiple field line resonances may be excited from the magnetopause to geosynchronous orbit by propagating compressional waves, with the power decreasing inward away from the magnetopause.

Kessel, Ramona L.↗

NASA NTRS1988

Design of the unmanned Multiple Exploratory Probe System (MEPS) for Mars observations

The unmanned Multiple Exploratory Probe System (MEPS) is designed for Mars observations in preparation for manned missions to the planet early in the 21st century. MEPS will test vehicle systems, provide important data about the Martian surface and atmosphere, and assist the planning of manned missions. This mission will be a precursor to the manned missions. MEPS will consist of six primary systems. A Command Information Center (CIC) will be employed as an onboard mission control, communications link, and observation post. The Space Transportation Main Engine (STME) will be used to provide the thrust for Earth-Mars transit following vehicle construction near the Space Station. A polar lander/Orbital Transfer Vehicle (OTV) will be deployed during transit to achieve a polar orbit about Mars. A secondary propulsion will be used to place MEPS into orbit about Mars; this system and the aerobrake will circularize the orbit. Following orbit circulation, a satellite will be deployed to observe the Martian surface and atmosphere and to study the space environment. Polar and equatorial lander systems will land on Mars with rovers to collect surface and atmospheric samples while on-board laboratories will provide initial sample study. Two solid rocket booster/payload vehicles will launch samples into a low Mars orbit. The OTV will rendezvous with each payload capsule and then transfer the samples to Earth for hands-on observation.

Source record↗

NASA NTRS1974

Orbit design concepts for Jupiter orbiter missions

Advanced mission and orbit planning efforts are currently in progress for a Mariner-class Jupiter orbiter. Baseline spacecraft and orbit design criteria are the goals of a NASA effort to define such a mission. Orbit design concepts that have been discovered during the early stages of mission planning are both challenging and exciting. A description is given of several such concepts that may greatly increase the flexibility and scientific return of orbiters designed for close study of the Galilean satellites and exploration of the Jovian system. Some new jargon is introduced in discussions to describe the exploitation of gravity-assist trajectories using the giant satellites for orbit control. Orbit 'pumping' and 'cranking' and 'resonance hopping' are defined and shown to be dynamically feasible means of controlling the orbit and, thus, the scientific return. A candidate encounter sequence is presented for an equatorial tour of the Galilean moons.

Uphoff, C.↗

NASA NTRS1980

Galilean satellite eclipse studies. I - Observations and satellite characteristics

Spectrophotometric light curves of 12 Galilean satellite eclipses are reported. The observations were made in 20 to 30 channels over the wavelength range 3240 to 10,500 A using the 200-in. telescope. The initial data processing is described. These data measure the Jovian aerosol content in the lower stratosphere and uppermost troposphere and the methane abundance in the lower stratosphere. The data are consistent with a lack of limb darkening on the Galilean satellites. The orbit of Callisto is shown to be inclined 0.08 + or - 0.02 deg to the equatorial plane of Jupiter.

Greene, T. F.↗

NASA NTRS1981

Magnetic field observations on DE-A and -B

Magnetic field observations are conducted on each of the DE-A and -B satellites by a triaxial fluxgate magnetometer. In the basic mode the instrumental resolution is + or - 1.5 nT; in addition, the DE-A magnetometer has two modes of higher resolution: + or - 0.25 nT and + or - 20 pT. The sampling rate is 16 vector samples per second in all modes. The experiment objectives include observations of field-aligned currents, magnetospheric equatorial currents, and ULF waves. These observations, taking full advantage of the specifically selected orbits of the two spacecraft and of the unique combination of instruments, are performed to achieve a better understanding of the electrodynamic coupling within the atmosphere-ionosphere-magnetosphere system and of wave-particle interactions which contribute to the coupling processes.

Farthing, W. H.↗