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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 NTRS2009

JPL Project Information Management: A Continuum Back to the Future

This slide presentation reviews the practices and architecture that support information management at JPL. This practice has allowed concurrent use and reuse of information by primary and secondary users. The use of this practice is illustrated in the evolution of the Mars Rovers from the Mars Pathfinder to the development of the Mars Science Laboratory. The recognition of the importance of information management during all phases of a project life cycle has resulted in the design of an information system that includes metadata, has reduced the risk of information loss through the use of an in-process appraisal, shaping of project's appreciation for capturing and managing the information on one project for re-use by future projects as a natural outgrowth of the process. This process has also assisted in connection of geographically disbursed partners into a team through sharing information, common tools and collaboration.

Information Management↗
NASA NTRS2004

The challenges of designing the rocker-bogie suspension for the Mars Exploration Rover

Over the past decade, the rocker-bogie suspension design has become a proven mobility application known for its superior vehicle stability and obstacle-climbing capability. Following several technology and research rover implementations, the system was successfully flown as part of Mars Pathfinder's Sojourner rover. When the Mars Exploration Rover (MER) Project was first proposed, the use of a rocker-bogie suspension was the obvious choice due to its extensive heritage. The challenge posed by MER was to design a lightweight rocker-bogie suspension that would permit the mobility to stow within the limited space available and deploy into a configuration that the rover could then safely use to egress from the lander and explore the Martian surface. This paper will describe how the MER rocker-bogie suspension subsystem was able to meet these conflicting design requirements while highlighting the variety of deployment and latch mechanisms employed in the design.

Voorhees, Chris↗
NASA NTRS1999

Sampling the Old and the New: Landing Site Proposals for the Dichotomy Boundary (6 S,210 W) and the Ares Vallis Headlands (2 S,18 W)

One of the goals of the Mars Pathfinder mission was to sample a diversity of rocks deposited by the Ares and Tiu Vallis floods. It was hoped that ancient highlands and younger lowlands material could be studied, as well as a diversity of rocks within these regions. Although Pathfinder found rocks that exhibited a number of textures and morphologies, several factors precluded the identification of a petrologic suite of rocks, if it was present. Namely among these were 1) The lack of geologic context for the rocks examined, 2) instrument limitations, and 3) pervasive dust and possible weathering finds. Based on the Pathfinder experience and incorporating recent results from Mars Global Surveyor and previous missions, two landing sites are proposed that can potentially overcome this problem and offer samples of ancient and recent Martian rock. The first site is at the dichotomy boundary, where ancient highlands and more recent lowlands meet. The second site is at the Ares Vallis headlands, where some of the source materials for the Pathfinder landing site may have been derived. Both of these sites meet the remote sensing and elevation constraints of the 2001 Lander mission but exhibit significant slopes and potential hazards in places. However, a properly placed ellipse can alleviate much of the concern, thereby offering two exciting sites that otherwise would not be chosen.

Bridges, N. T.↗
NASA NTRS1997

The Mars Rover Mobility System

The Mars Pathfinder SOJOURNER Rover vehicle has completed its mission. It explored the vicinity of the lander, probing the Martian surface while getting pictures of the rocks and the way they are arranged. It analyzed the chemical make up of the soil and the various rocks.

Mars Rover Mobility Sojourner Mars Pathfinder↗
NASA NTRS1994

(abstract) Scaling Nominal Solar Cell Impedances for Array Design

This paper discusses a task the objective of which is to characterize solar cell array AC impedance and develop scaling rules for impedance characterization of large arrays by testing single solar cells and small arrays. This effort is aimed at formulating a methodology for estimating the AC impedance of the Mars Pathfinder (MPF) cruise and lander solar arrays based upon testing single cells and small solar cell arrays and to create a basis for design of a single shunt limiter for MPF power control of flight solar arrays having very different inpedances.

solar cells solar arrays AC impedance Mars Pathfin↗
NASA NTRS2000

Rock Abrasion on Mars: Clues from the Pathfinder and Viking Landing Sites

A significant discovery of the Mars Pathfinder (MPF) mission was that many rocks exhibit characteristics of ventifacts, rocks that have been sculpted by saltating particles. Diagnostic features identifying the rocks as ventifacts am elongated pits, flutes, and grooves (collectively referred to as "flutes" unless noted otherwise). Faceted rocks or rock portions, circular pits, rills, and possibly polished rock surfaces are also seen and could be due, to aeolian abrasion. Many of these features were initially identified in rover images, where spatial resolution generally exceeded that of the IMP (Imager for Mars Pathfinder) camera. These images had two major limitations: 1) Only a limited number of rocks were viewed by the rover, biasing flute statistics; and 2) The higher resolution obtained by the rover images and the lack of such pictures at the Viking landing sites hampered comparisons of rock morphologies between the Pathfinder and Viking sites. To avoid this problem, rock morphology and ventifact statistics have been examined using new "super-resolution" IMP and Viking Lander images. Analyses of these images show that: 1) Flutes are seen on about 50% or more of the rocks in the near field at the MPF site; 2) The orientation of these flutes is similar to that for flutes identified in rover images; and 3) Ventifacts are significantly more abundant at the Pathfinder landing site than at the two Viking Landing sites, where rocks have undergone only a limited amount of aeolian abrasion. This is most likely due to the ruggedness of the Pathfinder site and a greater supply of abrading particles available shortly after the Arcs and Tiu Valles outflow channel floods.

Bridges, N. T.↗
NASA NTRS1995

(abstract) The Design of a Benign Fail-safe Mechanism Using a Low-melting-point Metal Alloy Coupler

Because the alpha proton X ray spectrometer (APXS) sensor head on the Mars Pathfinder rover, Sojourner, is placed on Martian soil by the deployment mechanism (ADM), the rover would be crippled if the actuator fails when the mechanism is in its deployed position, as rover ground clearance is then reduced to zero. This paper describes the unique fail-safe mounted on the ADM, especially the use of a low-temperature-melting alloy as a coupler device. The final form of the design is a low-melting-point metal pellet coupler, made from Cerrobend, in parallel with a Negator spring pack. In its solid state, the metal rigidly connects the driver (the actuator) and the driven part (the mechanism). When commanded, a strip heater wrapped around the coupler melts the metal pellet (at 60(deg)C), allowing the driven part to turn independent of the driver. The Negator spring retracts the mechanism to its fully stowed position. This concept meets all the design criteria, and provides an added benefit. When the metal hardens the coupler once again rigidly connects the actuator and the mechanism. The concept presented here can easily be applied to other applications. Anywhere release devices are needed, low-melting-point couplers can be considered. The issues to be concerned with are thermal isolation, proper setting of the parts before actuation, and possible outgassing concerns. However, when these issues are overcome, the resulting release mechanism can promise to be the most light, simple, power conserving alternative available.

low-melting-point alloys couplers Negator springs ↗
NASA NTRS1999

Examining Mars with SPICE

The International Mars Conference highlights the wealth of scientific data now and soon to be acquired from an international armada of Mars-bound robotic spacecraft. Underlying the planning and interpretation of these scientific observations around and upon Mars are ancillary data and associated software needed to deal with trajectories or locations, instrument pointing, timing and Mars cartographic models. The NASA planetary community has adopted the SPICE system of ancillary data standards and allied tools to fill the need for consistent, reliable access to these basic data and a near limitless range of derived parameters. After substantial rapid growth in its formative years, the SPICE system continues to evolve today to meet new needs and improve ease of use. Adaptations to handle landers and rovers were prototyped on the Mars pathfinder mission and will next be used on Mars '01-'05. Incorporation of new methods to readily handle non-inertial reference frames has vastly extended the capability and simplified many computations. A translation of the SPICE Toolkit software suite to the C language has just been announced. To further support cartographic calculations associated with Mars exploration the SPICE developers at JPL have recently been asked by NASA to work with cartographers to develop standards and allied software for storing and accessing control net and shape model data sets; these will be highly integrated with existing SPICE components. NASA specifically supports the widest possible utilization of SPICE capabilities throughout the international space science community. With NASA backing the Russian Space Agency and Russian Academy of Science adopted the SPICE standards for the Mars 96 mission. The SPICE ephemeris component will shortly become the international standard for agencies using the Deep Space Network. U.S. and European scientists hope that ESA will employ SPICE standards on the Mars Express mission. SPICE is an open set of standards, and all related specifications and software are freely distributed around the world. This poster describes the current state of SPICE system development, with special emphasis on current and planned support for Mars exploration missions.

Acton, Charles H.↗
NASA NTRS1998

Useful Radar Data for Mars 2001 Landing Site Selection

Radar data, of both Doppler-only and delay-Doppler varieties, played a useful role in the landing site certification process for Mars Pathfinder. Radar provides information on the elevation of the planetary surface, on its radar reflectivity and on the surface roughness. The elevation is important for proper entry, descent and landing, as is the reflectivity if a radar altimeter is to be used on the lander. Both the reflectivity and the surface roughness can measure the rockiness of the surface, important for a safe landing, as well as for rover trafficability. The spatial resolution of this Earth-based remote sensing technique is around 10 km in longitude by some 150 km in latitude. In the case of Pathfinder the regionally averaged properties were confirmed by ground truth at the landing site in Ares Vallis. The landing site assessment for Pathfinder relied principally on data from the 1995 Mars opposition when sub-Earth latitudes on Mars ranged from 16 to 22 degrees north. Data from earlier oppositions (1992-93, 1990, 1988-89) are available and cover latitudes from 25 south to 25 north at various longitudes. The available data will be presented at the symposium. The data are of varying quality, although ranging data is available for about 20 radar tracks per opposition, reflectivity and roughness analyses may not always be possible. Some older data are also available (1982, 1980) with range-only information.

Haldemann, A. F. C.↗
NASA NTRS1996

Back to Mars

Two decades after humanity's last exploration of the red planet, a new international program of Mars study will begin late this year when NASA's and Caltech's Jet Propulsion Laboratory launches its Mars Global Surveyor orbiting mission and its Mars Pathfinder lander and micro-rover.Spacecraft from Earth last visited Mars in 1976 when two Viking orbiters and two landers conducted a very successful survey of the entire planet from orbit and detailed studies of the surface at the two landing sites.

red planet Mars missions international program↗
NASA NTRS1999

Geologic Measurements using Rover Images: Lessons from Pathfinder with Application to Mars 2001

The Pathfinder Sojourner rover successfully acquired images that provided important and exciting information on the geology of Mars. This included the documentation of rock textures, barchan dunes, soil crusts, wind tails, and ventifacts. It is expected that the Marie Curie rover cameras will also successfully return important information on landing site geology. Critical to a proper analysis of these images will be a rigorous determination of rover location and orientation. Here, the methods that were used to compute rover position for Sojourner image analysis are reviewed. Based on this experience, specific recommendations are made that should improve this process on the '01 mission.

Bridges, N. T.↗
NASA NTRS2000

Constraints on Martian Soil Composition as Inferred from Viking XRFS and Pathfinder APXS and IMP Data

With the successful operation of the Alpha Proton X-Ray Spectrometer (APXS) during 1997's Mars Pathfinder (MPF) mission, geochemistry data are now available from three sites on Mars. APXS raw spectra for six soils and five rocks have been converted to compositional abundances. The Viking Lander X-Ray Fluorescence Spectrometer (XRFS) successfully measured elemental abundances of nine soils at Viking 1 and eight soils at Viking 2. Although the three landing sites are located in different parts of Mars, the soils exhibit broad similarities, with an iron-rich chemistry similar to that of palagonite. However, the Pathfinder sods show some significant differences from Viking soils, notably an enrichment in silica and depletion in sulfur. The XRFS samples consisted of near-surface and deep (up to 22 cm) soils acquired by a collector head at the cod of a retractable boom. It was possible to collect and analyze pebbles as large a 2 cm, but only sod, some in the form of consolidated clods, was sampled. In contrast, the APXS measured materials in situ. This resulted in MPF "rock" analyses that probably had a significant dust component and, as explored here, "soil" analyses that may have contained a rocky component We examine several possibilities to explain these differences and other attributes of the APXS and XRFS data sets: 1) The APXS soil measurements actually sampled a mixture of Viking-like soil and small bits of high-silica, low-sulfur rock, 2) The soils were derived from high-silica rocks mixed with a minor component of globally-homogenized dust; these soils are chemically distinct and have a separate geologic history from the Viking soils. 3) The weathering environment was different at the Pathfinder landing site compared to the Viking sites, and 4) Uncertainties in the XRFS and APXS measurements result in reported elemental abundances different than those that are actually present We show that none of the possibilities can be discounted, but that an MPF soil distinct in composition from Viking sods is best supported by the available data.

Bridges, N. T.↗
NASA NTRS2000

Visible Wavelength Spectroscopy of Ferric Minerals: A Key Tool for Identification of Ancient Martian Aqueous Environments

The mineralogic signatures of past aqueous alteration of a basaltic Martian crust may include iron oxides and oxyhydroxides, zeolites, carbonates, phyllosilicates, and silica. The identities, relative abundances, and crystallinities of the phases formed in a particular environment depend on physicochemical conditions. At one extreme, hot spring environments may be characterized by smectite-chlorite to talc-kaolinite silicate assemblages, plus crystalline ferric oxides dominated by hematite. However, most environments, including cold springs, pedogenic layers, and ponded surface water, are expected to deposit iron oxides and oxyhydroxides, carbonates, and smectite-dominated phyllosilicates. A substantial fraction of the ferric iron is expected to occur in nanophase form, with the exact mineralogy strongly influenced by Eh-pH conditions. Detection of these phases has been an objective of a large body of terrestrial telescopic, Mars orbital, and landed spectral investigations and in situ compositional measurements. However, clear identifications of many of these phases is lacking. Neither carbonate nor silica has been unequivocally detected by any method. Although phyllosilicates may occur near the limit of detection by remote sensing, in general they appear to occur in only poorly crystalline form. In contrast, compelling evidence for ferric iron minerals has been gathered by recent telescopic investigations, the Imager for Mars Pathfinder (IMP), and the Thermal Emission Spectrometer (TES) on the Mars Global Surveyor (MGS). These data yield two crucial findings: (1) In the global, high spatial resolution TES data set, highly crystalline ferric iron (as coarse-grained 'gray' hematite) has been recognized but with only very limited spatial occurrence and (2) Low-resolution telescopic reflectance spectroscopy, very limited orbital reflectance spectroscopy, and landed multispectral imaging provide strong indications that at least two broad classes of ferric iron minerals are commonplace in non-dust covered regions.

Murchie, Scott L.↗
NASA NTRS2005

Planetary Protection Issues in the Human Exploration of Mars

This workshop report, long delayed, is the first 21st century contribution to what will likely be a series of reports examining the effects of human exploration on the overall scientific study of Mars. The considerations of human-associated microbial contamination were last studied in a 1990 workshop ("Planetary Protection Issues and Future Mars Missions," NASA CP-10086, 1991), but the timing of that workshop allowed neither a careful examination of the full range of issues, nor an appreciation for the Mars that has been revealed by the Mars Global Surveyor and Mars Pathfinder missions. Future workshops will also have the advantage of Mars Odyssey, the Mars Exploration Rover missions, and ESA's Mars Express, but the Pingree Park workshop reported here had both the NCR's (1992) concern that "Missions carrying humans to Mars will contaminate the planet" and over a decade of careful study of human exploration objectives to guide them and to reconcile. A daunting challenge, and one that is not going to be simple (as the working title of this meeting, "When Ecologies Collide?" might suggest), it is clear that the planetary protection issues will have to be addressed to enable human explorers to safely and competently extend out knowledge about Mars, and its potential as a home for life whether martian or human.

Criswell, Marvin E.↗
NASA NTRS2013

Mars-GRAM 2010: Additions and Resulting Improvements

The Mars Global Reference Atmospheric Model (Mars-GRAM) is an engineering-level atmospheric model widely used for diverse mission applications. Mars-GRAM has been utilized during previous aerobraking operations in the atmosphere of Mars. Mars-GRAM has also been used in the prediction and validation of Mars Pathfinder hypersonic aerodynamics, the aerothermodynamic and entry dynamics studies for Mars Polar Lander, the landing site selection process for the Mars Science Laboratory (MSL), the Mars Aerocapture System Study (MASS) as well as the Aerocapture Technology Assessment Group (TAG). Most recently, Mars-GRAM 2010 was used to develop the onboard atmospheric density estimator that is part of the Autonomous Aerobraking Development Plan. The most recent release of Mars-GRAM 2010 contains several changes including an update to Fortran 90/95 and the addition of adjustment factors. Following the completion of a comparison analysis between Mars-GRAM, Thermal Emission Spectrometer (TES), as well as Mars Global Surveyor (MGS), Mars Odyssey (ODY), and Mars Reconnaissance Orbiter (MRO) aerobraking density data, adjustment factors were added to Mars-GRAM 2010 that alter the input data from National Aeronautics and Space Administration (NASA) Ames Mars General Circulation Model (MGCM) and the University of Michigan Mars Thermospheric General Circulation Model (MTGCM) for the mapping year 0 user-controlled dust case. The addition of adjustment factors resolved the issue of previous versions of Mars-GRAM being less than realistic when used for sensitivity studies for mapping year 0 and large optical depth values, such as tau equal to 3. Mars-GRAM was evaluated at locations and times of TES limb observations and adjustment factors were determined. For altitudes above 80 km and below 135 km, Mars-GRAM (MTGCM) densities were compared to aerobraking densities measured by Mars Global Surveyor (MGS), Mars Odyssey (ODY), and Mars Reconnaissance Orbiter (MRO) to determine the adjustment factors. The adjustment factors generated by this process had to satisfy the gas law as well as the hydrostatic relation and are expressed as a function of height (z), Latitude (Lat) and areocentric solar longitude (Ls). The greatest adjustments are made at large optical depths such as tau greater than 1. The addition of the adjustment factors has led to better correspondence to TES Limb data from 0-60 km altitude as well as better agreement with MGS, ODY and MRO data at approximately 90-130 km altitude. Improved Mars-GRAM atmospheric simulations for various locations, times and dust conditions on Mars will be presented at the workshop session. The latest results validating Mars-GRAM 2010 versus Mars Climate Sounder data will also be presented. Mars-GRAM 2010 updates have resulted in improved atmospheric simulations which will be very important when beginning systems design, performance analysis, and operations planning for future aerocapture, aerobraking or landed missions to Mars.

Justh, Hilary L.↗