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At least 1,171 records · Page 65
All sourcesNASA NTRSDOE OSTI
NASA NTRS2013

Reflectance Spectra Diversity of Silica-Rich Materials: Sensitivity to Environment and Implications for Detections on Mars

Hydrated silica-rich materials have recently been discovered on the surface of Mars by the Mars Exploration Rover (MER) Spirit, the Mars Reconnaissance Orbiter (MRO) Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), and the Mars Express Observatoire pour la Mineralogie, l'Eau, les Glaces, et l'Activite'(OMEGA) in several locations. Having been interpreted as hydrothermal deposits and aqueous alteration products, these materials have important implications for the history of water on the martian surface. Spectral detections of these materials in visible to near infrared (Vis NIR) wavelengths have been based on a H2O absorption feature in the 934-1009 nm region seen with Spirit s Pancam instrument, and on SiOH absorption features in the 2.21-2.26 micron range seen with CRISM. Our work aims to determine how the spectral reflectance properties of silica-rich materials in Vis NIR wavelengths vary as a function of environmental conditions and formation. Here we present laboratory reflectance spectra of a diverse suite of silica-rich materials (chert, opal, quartz, natural sinters and synthetic silica) under a range of grain sizes and temperature, pressure, and humidity conditions. We find that the H2O content and form of H2O/OH present in silica-rich materials can have significant effects on their Vis NIR spectra. Our main findings are that the position of the approx.1.4 microns OH feature and the symmetry of the approx.1.9 microns feature can be used to discern between various forms of silica-rich materials, and that the ratio of the approx.2.2 microns (SiOH) and approx.1.9 microns (H2O) band depths can aid in distinguishing between silica phases (opal-A vs. opal-CT) and formation conditions (low vs. high temperature). In a case study of hydrated silica outcrops in Valles Marineris, we show that careful application of a modified version of these spectral parameters to orbital near-infrared spectra (e.g., from CRISM and OMEGA) can aid in characterizing the compositional diversity of silica-bearing deposits on Mars. We also discuss how these results can aid in the interpretation of silica detections on Mars made by the MER Panoramic Camera (Pancam) and Mars Science Laboratory (MSL) Mast-mounted Camera (Mastcam) instruments.

Rice, M. S.↗
NASA NTRSDate not supplied

Expanding a Family of Mars Chemical Transportation Elements with a Large Vertical Lander Concept

In characterizing the trade space available for enabling human Mars missions, NASA’s Mars Architecture Team (MAT) has continues to developed a collection of concepts to assess the capabilities and constraints presented by a family of large Mars Chemical Transportation Elements (MACHETE). The purpose of this paper is to extend the MACHETE family with a new Large Vertical Lander (LVL) concept to increase our knowledge of the transportation trade space. The LVL is designed as a dedicated lander system capable of delivering a separate Mars Ascent Vehicle (MAV) fully-fueled to the surface of Mars. The addition of this concept enables exploring architecture alternatives that do not require either in-situ ascent propellant production or pre-deployment and subsequent surface transfer of ascent propellant.

Campaign↗
NASA NTRS1982

Mars - Near-infrared spectral reflectance of surface regions and compositional implications

Both morphological and compositional information are needed to define and characterize surface geologic units on Mars. A description is presented of new, near-infrared spectra (0.65 to 2.50 micrometers) for 11 regions on the Martian surface observed in 1978. The high photometric quality of these data combined with increased near-infrared spectral coverage provide new information about the spectral behavior and, therefore, the composition and physical nature of Martian surface materials. The spectral reflectances were obtained with the aid of a 2.2-m telescope located on Mauna Kea, Hawaii. A cooled (to 77 K) circular variable filter spectrometer with an InSb detector was used to measure alternatively Mars and the standard star Beta Geminorum. Attention is given to general spectral characteristics, the dark region composition, spectral evidence for water, and the 2.3 micrometer absorption.

Mccord, T. B.↗
NASA NTRS1972

Meteoroid impacts on Mars and the secondary particle environment

The degree to which the thin Martian atmosphere filters out meteoroids approaching the Martian surface was calculated by using a model of the meteoroid environment, a model of the Martian atmosphere, and equations of meteor physics. The secondary particle environment on the surface of Mars caused by the material ejected from meteoroid craters was modeled. The model consists of the mass distribution and the speed distribution of the secondary particles. Calculations were made of the penetration flux for aluminum structures on the Martian surface. The penetration hazard on the Martian surface was compared with the penetration hazard in space near Mars and on the lunar surface.

Humes, D. H.↗
NASA NTRS1967

The atmosphere of Mars.

Mars atmosphere surface pressure, radiative equilibrium temperatures, sunlight resonance scattering distribution, etc

SURFACE PRESSURE↗
NASA NTRS1974

Development of the Viking Mars lander thermal control subsystem design

Two Viking spacecraft, each consisting of a lander capsule coupled to an orbiter, will be launched toward Mars during the summer of 1975. About a year later, the orbiters will go into orbit around Mars and the landers will descend to the surface for 90-day landed missions. The lander must withstand a wide variety of environmental and operational conditions during all phases of the mission, including prelaunch sterilization. On the surface of Mars, the lander internal temperatures must be controlled under widely varying thermal environments and atmospheric conditions. The lander thermal design is based on the maximum use of passive techniques and is integrated into the overall vehicle design and operation. The solutions to the unusual combinations of design problems and a summary of the results of full scale model testing under simulated mission conditions are presented.

Morey, T. F.↗
NASA NTRS1981

Thermal inertia mapping of Mars from 60 deg S to 60 deg N

The considered region comprises 81% of the surface of Mars. Thermal inertia I is a composite surface property, which is equal to the square root of the product of three factors, including the thermal conductivity, the density, and the specific heat. I is the sole thermal parameter which governs the temperature variation of a periodically heated homogeneous surface, and, as such, is the prime intermediary between remote temperature observations and their geologic interpretation. The values for the thermal inertia found imply particulate surface materials. The variation in Martian surface thermal conductivity is about two orders of magnitude. Three large regions of low-inertia material are defined. Low-inertia material always possesses high albedo. There is a general tendency for higher-thermal-inertia surfaces to be darker but exceptions occur which may be related to a thin mantling of light dust or bonding of light material.

Palluconi, F. D.↗
NASA NTRS1990

Orbiter-orbiter and orbiter-lander tracking using same-beam interferometry

Two spacecraft orbiting Mars may be tracked simultaneously by a single earth-based antenna. Same-beam interferometric techniques, using two widely separated antennas, produce a spacecraft-spacecraft measurement in the plane of the sky, complementary to the line-of-sight Doppler information. This paper presents an overview of the same-beam interferometric measurement technique, a measurement error analysis, and examples of the application of same-beam interferometry to orbit determination. For the case of Mars Observer and the Soviet Mars '94 mission, orbit determination improvement up to an order of magnitude is found. Relative tracking between a Mars orbiter and a lander fixed on the surface of Mars is also studied. The lander location may be determined to a few meters, while the orbiter ephemeris may be determined with accuracy similar to the orbiter-orbiter case.

Folkner, W. M.↗
NASA NTRS1992

Temporal variability of the surface and atmosphere of Mars: Viking Orbiter color observations

We are near the final stages in the processing of a large Viking Orbiter global color dataset. Mosaics from 57 spacecraft revolutions (or 'revs' hereafter) were produced, most in both red and violet or red, green, and violet filters. Phase angles range from 13 deg to 85 deg. A total of approximately 2000 frames were processed through radiometric calibration, cosmetic cleanup, geometric control, reprojection, and mosaicking into single-rev mosaics at a scale of 1 km/pixel. All of the mosaics are geometrically tied to the 1/256 deg/pixel Mars Digital Image Mosaic (MDIM). Photometric normalization is in progress, to be followed by production of a 'best coverage' global mosaic at a scale of 1/64 deg/pixel (0.923 km/pixel). Global coverage is near 100 percent in red-filter mosaics and 98 percent and 60 percent in corresponding violet- and green-filter mosaics, respectively. Soon after completion, all final datasets (including single-rev mosaics) will be distributed to the planetary community on compact disks.

Mcewen, A. S.↗
NASA NTRS1992

Orbiter-orbiter and orbiter-lander tracking using same-beam interferometry

Two spacecraft orbiting Mars will subtend a small angle as viewed from Earth. This angle will usually be smaller than the beam width of a single radio antenna. Thus the two spacecraft may be tracked simultaneously by a single Earth-based antenna. The same-beam interferometry (SBI) technique involves using two widely separated antennas, each observing the two spacecraft, to produce a measurement of the angular separation of the two spacecraft in the plane of the sky. The information content of SBI data is thus complementary to the line-of-sight information provided by conventional Doppler data. The inclusion of SBI data with the Doppler data in a joint orbit estimation procedure can desensitize the solution to gravity mismodeling and result in improved orbit determination accuracy. This article presents an overview of the SBI technique, a measurement error analysis, and an error covariance analysis of some examples of the application of SBI to orbit determination. For hypothetical scenarios involving the Mars Observer and the Russian Mars '94 spacecraft, orbit determination accuracy improvements of up to an order of magnitude are predicted, relative to the accuracy that can be obtained by using only Doppler data acquired separately from each spacecraft. Relative tracking between a Mars orbiter and a lander fixed on the surface of Mars is also studied. Results indicate that the lander location may be determined to a few meters, while the orbiter ephemeris may be determined with accuracy similar to the orbiter-orbiter case.

Folkner, W. M.↗
NASA NTRS2000

Field Experiments with Planetary Surface Rovers: Lessons for Mars Mission Architecture

Over the last decade, a variety of field experiments have been performed that simulate operations of a rover on Mars. These, in combination with the Pathfinder experience, lead to a realistic assessment of rover mission capabilities and to recommendations for rover technology and mission architecture to improve the science return of Mars exploration. A table summarizes field experiments that represent a range of possible mission designs and operational strategies. The experiments varied by the type and quality of imaging systems and other instrumentation, the use of orbital and aerial imaging and spectroscopy, the communcation bandwidth and command strategy, and the distance traveled. All mission simulations were blind field tests operated by science teams whose interpretations were compared to field ground truth providing an assessment of the accuracy of remote science interpretations and a better understanding of where improvements are needed.

Stoker, Carol↗
NASA NTRS2000

Mars Stratigraphy Mission

The Mars Stratigraphy Mission lands a rover on the surface of Mars which descends down a cliff in Valles Marineris to study the stratigraphy. The rover carries a unique complement of instruments to analyze and age-date materials encountered during descent past 2 km of strata. The science objective for the Mars Stratigraphy Mission is to identify the geologic history of the layered deposits in the Valles Marineris region of Mars. This includes constraining the time interval for formation of these deposits by measuring the ages of various layers and determining the origin of the deposits (volcanic or sedimentary) by measuring their composition and imaging their morphology.

Budney, C. J.↗
NASA NTRS2004

Distribution of Near-Surface Ground Ice on Mars

During the course of this grant we made significant progress in our understanding of martian ground ice in areas of theoretical and laboratory research. We recently completed a manuscript comparing a new map of ground-ice stability with leakage neutron data for the southern hemisphere . In this manuscript we incorporated several improvements to a model of ground ice stability. We quantitatively compared measured epithermal-neutron flux with predicted ice-table burial depth and found that the observed distribution of ground ice is consistent with ice in diffusive equilibrium with the atmosphere. In addition to this theoretical study we have adapted an experimental apparatus, designed for measuring ice condensation in antarctic soils , to martian permafrost.

Mellon, Michael T.↗
NASA NTRS2004

Using RSVP for analyzing state and previous activities for the Mars Exploration Rovers

Current developments in immersive environments for mission planning include several tools which make up a system for performing and rehearsing missions. This system, known as the Rover Sequencing and Visualization Program (RSVP), includes tools for planning long range sorties for highly autonomous rovers, tools for planning operations with robotic arms, and advanced tools for visualizing telemetry from remote spacecraft and landers. One of the keys to successful planning of rover activities is knowing what the rover has accomplished to date and understanding the current rover state. RSVP builds on the lessons learned and the heritage of the Mars Pathfinder mission This paper will discuss the tools and methodologies present in the RSVP suite for examining rover state, reviewing previous activities, visually comparing telemetered results to rehearsed results, and reviewing science and engineering imagery. In addition we will present how this tool suite was used on the Mars Exploration Rovers (MER) project to explore the surface of Mars.

Mars Exploration Rover (MER)↗
NASA NTRS2004

The Mars Exploration Rover Project

The twin rovers of the Mars Exploration Rover Project successfully landed on the surface of Mars in January 2004, and initiated a highly successful science and exploration campaign. This marked the culmination of an unprecedented four-year effort to design, build, launch, and operate two of the most complex planetary spacecraft ever built. The project was started in the aftermath of the 1999 Mars mission failures, and was commissioned to take advantage of the highly advantageous 2003 opportunity. The development schedule from project start to launch was only 35 months, so schedule management was the most significant challenge facing the project. This problem was compounded when early assumptions about the extent of design heritage from Mars Pathfinder proved to be flawed. The project derived a number of useful lessons learned in solving these challenges that can be applied to future missions.

Mars↗