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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 NTRS2020

The Varied Sources of Faculae-Forming Brines in Ceres’ Occator Crater Emplaced via Hydrothermal Brine Effusion

Before acquiring highest-resolution data of Ceres, questions remained about the emplacement mechanism and source of Occator crater’s bright faculae. Here we report that brine effusion emplaced the faculae in a brine-limited, impact-induced hydrothermal system. Impact-derived fracturing enabled brines to reach the surface. The central faculae, Cerealia and Pasola Facula, postdate the central pit, and were primarily sourced from an impact-induced melt chamber, with some contribution from a deeper, pre-existing brine reservoir. Vinalia Faculae, in the crater floor, were sourced from the laterally extensive deep reservoir only. Vinalia Faculae are comparatively thinner and display greater ballistic emplacement than the central faculae because the deep reservoir brines took a longer path to the surface and contained more gas than the shallower impact-induced melt chamber brines. Impact-derived fractures providing conduits, and mixing of impact-induced melt with deeper endogenic brines, could also allow oceanic material to reach the surfaces of other large icy bodies.

J. E. C. Scully↗
NASA NTRS2002

Interaction Between Surface Heat Budgets, Sea Surface Temperature and Deep Convection in the Tropical Western Pacific

The surface heat budgets, sea surface temperature (SST), clouds and winds in the tropical western Pacific are analyzed and compared for the periods April-June 1998 and 1999. The spring of 1998 is in the later phase of a strong El Nino, whereas the spring of 1999 is in a period of a La Nina. The surface shortwave (SW) and longwave (LW) radiative fluxes are retrieved from Japanese Geostationary Meteorological Satellite radiance measurements, while the surface turbulent fluxes (latent and sensible heat) are derived from SSM/I-Inferred surface air humidity and winds. The SST and sea-air temperature differences are taken from NCEP/NCAR reanalysis. Deep convection is inferred from the outgoing longwave radiation of NOAA's polar-orbiting satellites. The longitudinal shift in maximum SST, deep convection and winds during El Nino and La Nina have a large impact on the spatial distribution of surface heating. Changes in clouds between these two periods have a large impact on the monthly-mean radiative heating, exceeding 60 W m(exp -2) over large oceanic regions. Similarly, the differences in wind speeds and SST have a large impact on the latent cooling, exceeding 40 W m(exp -2) over large oceanic areas. However, the maximum impacts on radiative and latent heat fluxes occur in different regions. The regions of maximum impact on radiative fluxes coincide with the regions of maximum change in clouds, whereas regions of maximum impact on turbulent heat fluxes coincide with the regions of maximum change in trade winds. The time-evolution of SST in relation to that of surface heat fluxes and winds are investigated and compared between the two El Nino and La Nina periods. In regions where wind speeds (or wind stresses) are large, the change in SST agrees well with the change in the net surface heating, indicating a deep ocean mixed layer associated with strong trade winds. On the other hand, in regions where radiative fluxes are large, the change in SST does not agree well with the change in the net surface heating, indicating the importance of solar radiation penetrating through the bottom of the shadow ocean mixed layer.

Chou, Shu-Hsien↗
NASA NTRS1974

Petrology of the highlands massifs at Taurus-Littrow - An analysis of the 2-4 mm soil fraction

The petrography, phase chemistry, and Ar-40/Ar-39 ages of 2-4 mm fragments from the soils of both mare and highlands stations sampled by Apollo 17 are studied. It is found that the massifs consist of a complex stratigraphy of interlayered noritic breccias of varying metamorphic grades, melt rocks, and anorthositic rocks. A stratigraphic correlation of the lithologies within the North Massif and the South Massif is carried out. The petrogenesis of rock types with respect to thermal and impact history is discussed. The observed spinel cataclasites may represent relatively deep material sampled by the Serenitatis event.

Bence, A. E.↗
NASA NTRS1986

A conceptual 34-meter antenna feed configuration for joint DSN/SETI use from 1 to 10 GHz

The very satisfactory performance of a conceptual 34-m DSS-12 type HA-Dec antenna feed sysem over the frequency range of 1 to 10 GHz is demonstrated. A seven-feedhorn baseline design is developed which will allow Search for Extra-Terrestrial Intelligence (SETI) investigations using each horn over a 1.4:1 frequency range. A gain/system noise temperature (G/T) figure of merit is calculated for the frequency range of each horn; it is found that system performance down to 20 deg elevation is possible with a G/T degradation of less than 3 dB at every frequency. The design presented here will allow shared but independent antenna use by the Deep Space Network (DSN) and SETI with a minimum of operational impacts to DSN functions and no intrusions into the DSN microwave equipment configuration.

Slobin, S. D.↗
NASA NTRS2016

Orion EFT-1 Cavity Heating Tile Experiments and Environment Reconstruction

Developing aerothermodynamic environments for deep cavities, such as those produced by micrometeoroids and orbital debris impacts, poses a great challenge for engineers. In order to assess existing cavity heating models, two one-inch diameter cavities were flown on the Orion Multi-Purpose Crew Vehicle during Exploration Flight Test 1 (EFT1). These cavities were manufactured with depths of 1.0 in and 1.4 in, and they were both instrumented. Instrumentation included surface thermocouples upstream, downstream and within the cavities, and additional thermocouples at the TPS-structure interface. This paper will present the data obtained, and comparisons with computational predictions will be shown. Additionally, the development of a 3D material thermal model will be described, which will be used to account for the three-dimensionality of the problem when interpreting the data. Furthermore, using a multi-dimensional inverse heat conduction approach, a reconstruction of a time- and space-dependent flight heating distribution during EFT1 will be presented. Additional discussions will focus on instrumentation challenges and calibration techniques specific to these experiments. The analysis shown will highlight the accuracies and/or deficiencies of current computational techniques to model cavity flows during hypersonic re-entry.

Salazar, Giovanni↗
NASA NTRS2017

Legacy of the Asteroid Redirect Robotic Mission (ARRM)

NASA’s proposed Asteroid Redirect Robotic Mission (ARRM) began with the recognition in a 2010 NASA study that emerging high-power solar electric propulsion technology could be used to rendezvous with, capture, and return an entire, very small (~10,000 kg), near Earth asteroids to the International Space Station. A 2011 workshop by the Keck Institute for Space Studies (KISS) extended the earlier NASA study to asteroid masses of order 500,000 kg by returning them to cislunar space. Subsequent detailed NASA studies in 2013-2014 confirmed the feasibility of this concept. This led to the establishment of the Asteroid Redirect Mission program that consisted of a robotic mission to return multiple tons of asteroid material to cislunar space and a crewed mission to rendezvous with the robotic vehicle, perform two extra vehicular activities (EVAs), collect samples of the asteroid material, and return this material to Earth. Implementation of ARRM got midway through Phase B before being cancelled in April 2017. Although ARRM was cancelled, it has left a near-term legacy of positive impacts to the human spaceflight community, the planetary defense community, the deep space science community, and asteroid mining interests.

Brophy, John R.↗
NASA NTRS1987

Impact on the earth, ocean and atmosphere

On the basis of finite-difference techniques, cratering flow calculations are used to obtain the spatial attenuation of shock pressure with radius along the impact axis for the impact of silicate rock and iron impactors on a silicate half-space at speeds of 5 to 45 km/sec. Upon impact of a 10 to 30 km diameter silicate or water object onto a 5 km deep ocean overlying a silicate half-space planet at 30 km/sec, it is found that from 12 to 15 percent of the incident energy is coupled into the water. The mass of atmosphere lost due to impacts of 1 to 5 km radius projectiles is calculated.

Ahrens, Thomas J.↗
NASA NTRS2007

Impacts of Center of Mass Shifts on Messenger Spacecraft Operations

The MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) has successfully completed its first three years of flight operations following launch on August 3, 2004. As part of NASA s Discovery Program, MESSENGER will observe Mercury during flybys in 2008 and 2009, as well as from orbit beginning in March 2011. This paper discusses the impact that center of mass (CM) location changes have had on many mission activities, particularly angular momentum management and maneuver execution. Momentum trends were altered significantly following the first deep-space maneuver, and these changes were related to a change in the CM. The CM location also impacts maneuver execution, and uncertainties in its location led to the significant direction errors experienced at trajectory correction maneuver 11. Because of the spacecraft sensitivity to CM location, efforts to estimate its position are important to momentum and maneuver prediction. This paper summarizes efforts to estimate the CM from flight data, as well as the operational strategy to handle CM uncertainties and their impact on momentum trends and maneuver execution accuracy.

O'Shaughnessy, D. J.↗
NASA NTRS2003

Craters on Mars: Global Geometric Properties from Gridded MOLA Topography

Impact craters serve as natural probes of the target properties of planetary crusts and the tremendous diversity of morphological expressions of such features on Mars attests to their importance for deciphering the history of crustal assembly, modification, and erosion. This paper summarizes the key findings associated with a five year long survey of the three-dimensional properties of approx. 6000 martian impact craters using finely gridded MOLA topography. Previous efforts have treated representative subpopulations, but this effort treats global properties from the largest survey of impact features from the perspective of their topography ever assimilated. With the Viking missions of the mid-1970 s, the most intensive and comprehensive robotic expeditions to any Deep Space location in the history of humanity were achieved, with scientifically stunning results associated with the morphology of impact craters. The relationships illustrated and suggest that martian impact features are remarkably sensitive to target properties and to the local depositional processes.

J.B. Garvin↗
NASA NTRS2004

The Case for Deep Space Telecommunications Relay Stations

Each future mission to Jupiter and beyond must carry the traditional suite of telecommunications systems for command and control and for mission data transmission to earth. The telecommunications hardware includes the large antenna and the high-power transmitters that enable the communications link. Yet future spacecraft will be scaled down from the hallmark missions of Galileo and Cassini to Jupiter and Saturn, respectively. This implies that a higher percentage of the spacecraft weight and power must be dedicated to telecommunications system. The following analysis quantifies this impact to future missions and then explores the merits of an alternative approach using deep space relay stations for the link back to earth. It will be demonstrated that a telecommunications relay satellite would reduce S/C telecommunications weight and power sufficiently to add one to two more instruments.

Chandler, Charles W.↗
NASA NTRS1992

Asteroids and Archaean crustal evolution: Tests of possible genetic links between major mantle/crust melting events and clustered extraterrestrial bombardments

Since the oldest intact terrestrial rocks of ca. 4.0 Ga and oldest zircon xenocrysts of ca. 4.3 Ga measured to date overlap with the lunar late heavy bombardment, the early Precambrian record requires close reexamination vis a vis the effects of megaimpacts. The identification of microtektite-bearing horizons containing spinals of chondritic chemistry and Ir anomalies in 3.5-3.4-Ga greenstone belts provides the first direct evidence for large-scale Archaean impacts. The Archaean crustal record contains evidence for several major greenstone-granite-forming episodes where deep upwelling and adiabatic fusion of the mantle was accompanied by contemporaneous crustal anatexis. Isotopic age studies suggest evidence for principal age clusters about 3.5, 3.0, and 2.7 (+/- 0.8) Ga, relics of a ca. 3.8-Ga event, and several less well defined episodes. These peak events were accompanied and followed by protracted thermal fluctuations in intracrustal high-grade metamorphic zones. Interpretations of these events in terms of internal dynamics of the Earth are difficult to reconcile with the thermal behavior of silicate rheologies in a continuously convecting mantle regime. A triggering of these episodes by mantle rebound response to intermittent extraterrestrial asteroid impacts is supported by (1) identification of major Archaean impacts from microtektite and distal ejecta horizons marked by Ir anomalies; (2) geochemical and experimental evidence for mantle upwelling, possibly from levels as deep as the transition zone; and (3) catastrophic adiabatic melting required to generate peridotitic komatites. Episodic differentiation/accretion growth of sial consequent on these events is capable of resolving the volume problem that arises from comparisons between modern continental crust and the estimated sial produced by continuous two-stage mantle melting processes. The volume problem is exacerbated by projected high accretion rates under Archaean geotherms. It is suggested that impact shock effects have been largely obscured by (1) outpouring of voluminous basic/ultrabasic lavas, inundating shock-deformed crust and extending beyond the perimeters of impact excavated basins; (2) gravity subsidence and downfaulting of terrestrial maria, accounting for the burial and anatexis of subgreenstone basement; and (3) extensive shearing and recrystallization at elevated temperatures of impact structure, breccias, and mineral deformation features beneath impact-excavated basins, relics of which may be retained in structural windows in high-grade metamorphic terranes.

Glikson, A. Y.↗
NASA NTRS2015

The Degradational History of Endeavour Crater, Mars

Endeavour crater (2.28 deg S, 354.77 deg E) is a Noachian-aged 22 km-diameter impact structure of complex morphology in Meridiani Planum. The degradation state of the crater has been studied using Mars Reconnaissance Orbiter and Opportunity rover data. Exposed rim segments rise approximately 10 m to approximately 100 m above the level of the embaying Burns Formation and the crater is 200-500 m deep with the southern interior wall exposing over approximately 300 m relief. Both pre-impact rocks (Matijevic Formation) and Endeavour impact ejecta (Shoemaker Formation) are present at Cape York, but only the Shoemaker crops out (up to approximately 140 m) along the rim segment from Murray Ridge to Cape Tribulation. Study of pristine complex craters Bopolu and Tooting, and morphometry of other martian complex craters, enables us to approximate Endeavour's pristine form. The original rim likely averaged 410 m (+/-)200 m in elevation and a 250-275 m section of ejecta ((+/-)50-60 m) would have composed a significant fraction of the rim height. The original crater depth was likely between 1.5 km and 2.2 km. Comparison between the predicted original and current form of Endeavour suggests approximately 100-200 m rim lowering that removed most ejecta in some locales (e.g., Cape York) while thick sections remain elsewhere (e.g., Cape Tribulation). Almost complete removal of ejecta at Cape York and minimal observable offset across fractures indicates current differences in rim relief are not solely due to original rim relief. Rim segments are embayed by approximately 100-200 m thickness of plains rocks outside the crater, but thicker deposits lie inside the crater. Ventifact textures confirm ongoing eolian erosion with the overall extent difficult to estimate. Analogy with degraded Noachian-aged craters south of Endeavour, however, suggests fluvial erosion dominated rim degradation in the Noachian and was likely followed by approximately 10s of meters modification by alternate processes. Such degradation is consistent with 1) the interpretation of a pediment on the rim flanks of Endeavour, 2) the formation of features such as Marathon Valley, 3) the nearly complete removal of ejecta at Cape York, 4) preservation of a thicker section of ejecta at Cape Tribulation and perhaps, 5) the origin of some gaps in the rim around the crater. A paucity of debris shed from the rim indicates most degradation occurred prior to embayment by the plains rocks.

Grant, J. A.↗
NASA NTRS2009

One-Hundred-km-Scale Basins on Enceladus: Evidence for an Active Ice Shell

Stereo-derived topographic mapping of 50% of Enceladus reveals at least 6 large-scale, ovoid depressions (basins) 90-175 km across and 800-to-1500 m deep and uncorrelated with geologic boundaries. Their shape and scale are inconsistent with impact, geoid deflection, or with dynamically supported topography. Isostatic thinning of Enceladus ice shell associated with upwellings (and tidally-driven ice melting) can plausibly account for the basins. Thinning implies upwarping of the base of the shell of 10-20 km beneath the depressions, depending on total shell thickness; loss of near-surface porosity due to enhanced heat flow may also contribute to basin lows. Alternatively, the basins may overly cold, inactive, and hence denser ice, but thermal isostasy alone requires thermal expansion more consistent with clathrate hydrate than water ice. In contrast to the basins, the south polar depression (SPD) is larger (~350 wide) and shallower (~0.4-to-0.8 km deep) and correlates with the area of tectonic deformation and active resurfacing. The SPD also differs in that the floor is relatively flat (i.e., conforms roughly to the global triaxial shape, or geoid) with broad, gently sloping flanks. The relative flatness across the SPD suggests that it is in or near isostatic equilibrium, and underlain by denser material, supporting the polar sea hypothesis of Collins and Goodman. Near flatness is also predicted by a crustal spreading origin for the "tiger stripes (McKinnon and Barr 2007, Barr 2008); the extraordinary, high CIRS heat flows imply half-spreading rates in excess of 10 cm/yr, a very young surface age (~250,000 yr), and a rather thin lithosphere (hence modest thermal topography). Topographic rises in places along the outer margin of the SPD correlate with parallel ridges and deformation along the edge of the resurfaced terrain, consistent with a compressional, imbricate thrust origin for these ridges, driven by the spreading.

Schenk, Paul M.↗
NASA NTRS1978

Emergence of the continents

If early degassing of the Earth produced a global ocean several km deep overlying a global sialic crust, then late heavy bombardment of that crust by basin forming impacting bodies would have produced topography such that by 4 billion years ago dry continential landmasses would stand above sea level. From extrapolation of lunar crater statistics, at least 50% of an original global crust on the earth would have been converted into basins averaging 4 km deep after isostatic adjustment. These basins formed the sink into which such a global ocean would drain. If the ocean was initially 2 km deep, then approximately 50% of the early Earth would have stood above sea level when the late heavy bombardment came to a close.

Frey, H.↗
NASA NTRS1972

Simultaneous impact and lunar craters

The existence of large terrestrial impact crater doublets and crater doublets that have been inferred to be impact craters on Mars suggests that simultaneous impact of two or more bodies can occur at nearly the same point on planetary surfaces. An experimental study of simultaneous impact of two projectiles near one another shows that doublet craters with ridges perpendicular to the bilateral axis of symmetry result when separation between impact points relative to individual crater diameter is large. When separation is progressively less, elliptical craters with central ridges and peaks, and circular craters with deep round bottoms are produced. These craters are similar in structure to many of the large lunar craters. Results suggest that the simultaneous impact of meteoroids near one another may be an important mechanism for the production of central peaks in large lunar craters.

Oberbeck, V. R.↗
NASA NTRS1975

A seismic refraction technique used for subsurface investigations at Meteor Crater, Arizona

A seismic refraction technique for interpreting the subsurface shape and velocity distribution of an anomalous surface feature such as an impact crater is described. The method requires the existence of a relatively deep refracting horizon and combines data obtained from both standard shallow refraction spreads and distant offset shots by using the deep refractor as a source of initial arrivals. Results obtained from applying the technique to Meteor crater generally agree with the known structure of the crater deduced by other investigators and provide new data on an extensive fractured zone surrounding the crater. The breccia lens is computed to extend roughly 190 m below the crater floor, about 30 m less than the value deduced from early drilling data. Rocks around the crater are fractured as distant as 900 m from the rim crest and to a depth of at least 800 m beneath the crater floor.

Ackermann, H. D.↗
NASA NTRS1988

Environmental projects. Volume 6: Environmental assessment. New 34-meter antenna at Venus site

The Jet Propulsion Lab has proposed replacing the 26-meter antenna at the Venus Station of the Goldstone Deep Space Communications Complex with a new 34-meter antenna. An environmental impact assessment of this proposed change is presented. It is concluded that the proposed antenna and its operation would not result in significant adverse impacts to the physical or human environment. It will, however, be necessary to manage electromagnetic transmissions from the antenna in such a manner as to ensure safe operation.

Kushner, L.↗