Mars Exploration Rovers orbit detemination system modeling
This paper will discuss the system modeling for two nearly identical spacecrafts, Mars Exploration Rovers; Spirit and Opportunity.
orbit determination↗
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Ground testing of the Li-ion batteries in support of JPL's 2003 Mars Exploration Rover Mission
In early 2004, JPL successfully landed two Rovers, named Spirit and Opportunity, on the surface of Mars after traveling > 300 million miles over a 6-7 month period. In order to operate for extended duration on the surface of Mars, both Rovers are equipped with rechargeable Lithium-ion batteries, which were designed to aid in the launch, correct anomalies during cruise, and support surface operations in conjunction with a triple-junction deployable solar arrays. The requirements of the Lithium-ion battery include the ability to provide power at least 90 sols on the surface of Mars, operate over a wide temperature range (-20(deg)C to +4O(deg)C), withstand long storage periods (e.g., cruise period), operate in an inverted position, and support high currents (e.g., firing pyro events). In order to determine the viability of meeting these requirements, ground testing was performed on a Rover Battery Assembly Unit (RBAU), consisting of two 8-cell 8 Ah lithium-ion batteries connected in parallel. The RBAU upon which the performance testing was performed is nearly identical to the batteries incorporated into the two Rovers currently on Mars. The testing performed includes, (a) performing initial characterization tests (discharge capacity at different temperatures), (b) simulating the launch conditions, (c) simulating the cruise phase conditions (including trajectory corrections), (d) simulating the entry, decent, and landing pulse load profile (if required to support the pyros) (e) simulating the Mars surface operation mission simulation conditions, as well as, (f) assessing performance capacity loss and impedance characteristics as a function of temperature and life. As will be discussed, the lithium-ion batteries (fabricated by LithiodYardney, Inc.) were demonstrated to far exceed the requirements defined by the mission, and are projected to support an extended mission (> 2 years) with margin to spare.
Li-ion batteries↗
SUBMM wave superconduction hot-electron direct detectors
Recently, we have presented a concept for a hot-electron direct detector (HEDD) capable of counting single millimeter-wave photons. Such a detector meets the needs of future space far-infrared applications and can be used for background-limited detector arrays on missions like SPIRIT, 10-m filled aperture telescope, SAFIR, and SPECS.
hot-electron electron-phonon direct detectors subm↗
SPECS: The Kilometer-baseline Far-IR Interferometer in NASA's Space Science Roadmap Presentation
A viewgraph presentation describing the Submillimeter Probe of the Evolution of Cosmic Structure (SPECS) mission is shown. The topics include: 1) Context: community planning and study status; 2) Science goals; 3) Mission requirements; 4) Mission concepts for SPIRIT and SPECS; and 5) Tethered formation flying, a key enabling technology.
Abel, Tom↗
Mechanically Strong, Polymer Cross-linked Aerogels (X-Aerogels)
Aerogels comprise a class of low-density, high porous solid objects consisting of dimensionally quasi-stable self-supported three-dimensional assemblies of nanoparticles. Aerogels are pursued because of properties above and beyond those of the individual nanoparticles, including low thermal conductivity, low dielectric constant and high acoustic impedance. Possible applications include thermal and vibration insulation, dielectrics for fast electronics, and hosting of functional guests for a wide variety of optical, chemical and electronic applications. Aerogels, however, are extremely fragile materials, hence they have found only limited application in some very specialized environments, for example as Cerenkov radiation detectors in certain types of nuclear reactors, aboard spacecraft as collectors of hypervelocity particles (refer to NASA's Stardust program) and as thermal insulators on planetary vehicles on Mars (refer to Sojourner Rover in 1997 and Spirit and Opportunity in 2004). Along these lines, the X-Aerogel is a new NASA-developed strong lightweight material that has resolved the fragility problem of traditional (native) aerogels. X-Aerogels are made by applying a conformal polymer coating on the surfaces of the skeletal nanoparticles of native aerogels (see Scanning Electron Micrographs). Since the relative amounts of the polymeric crosslinker and the backbone are comparable, X-Aerogels can be viewed either as aerogels modified by the templated accumulation of polymer on the skeletal nanoparticles, or as nanoporous polymers made by remplated casting of polymer on a nanostructured framework. The most striking feature of X-Aerogels is that for a nominal 3-fold increase in density (still a ultralighweight material), the mechanical strength can be up to 300 times higher than the strength of the underlying native aerogel. Thus, X-Aerogels combine a multiple of the specific compressive strength of steel, with the the thermal conductivity of styrofoam. X-Aerogels have been demonstrated with several polymers such as polyurethanes/polyureas, epoxies and polyolefins, while crosslinking of approximately 35 different oxide aerogels yields a range of dimensionally stable, porous lightweight materials with unique combinations of structural, magnetic and optical properties. The main theme in materials development for space exploration is multifunction. For example, use of one material for thermal insulation/structural component will free weight for useful payload. In that regard, X-aerogels are evaluated at NASA for cryogenic fuel storage tanks and for spacesuits. Along the same lines, major impact fro X-Aerogels is also expected in commercial applications for thermal/acoustic insulation, in catalytic reformers and converters, in filtration membranes and membranes for fuel cells, as platforms for optical, electrical and magnetic sensors, and as lightweight structural component for aircraft and satellites.
Leventis, Nicholas↗
Lessons Learned from Seven Space Shuttle Missions
Much can be learned from well-written descriptions of the technical and organizational factors that lead to an accident. Subsequent analysis by third parties of investigation reports and associated evidence collected during the investigations can lead to additional insight. Much can also be learned from documented close calls that do not result in loss of life or a spacecraft, such as the Mars Exploration Rover Spirit software anomaly, the SOHO mission interruption, and the NEAR burn anomaly. Seven space shuttle incidents fall into the latter category: Rendezvous Target Failure On STS-41B; Rendezvous Radar Anomaly and Trajectory Dispersion-STS-32 ;Rendezvous Lambert Targeting Anomaly-STS-49; Rendezvous Lambert Targeting Anomaly-STS-51; Zero Doppler Steering Maneuver Anomaly-STS-59; Excessive Propellant Consumption During Rendezvous-STS-69; Global Positioning System Receiver and Associated Shuttle Flight Software Anomalies-STS-91 Procedural work-arounds or software changes prevented them from threatening mission success. Extensive investigations, which included the independent recreation of the anomalies by multiple Shuttle Program organizations, were the key to determining the cause, accurately assessing risk, and identifying software and software process improvements. Lessons learned from these incidents not only validated long-standing operational best practices, but serve to promote discussion and mentoring among Program personnel and are applicable to future space flight programs.
Goodman, John↗
Identification of Iron-Bearing Phases on the Martian Surface and in Martian Meteorites and Analogue Samples by Moessbauer Spectroscopy
The Moessbauer spectrometers on the Mars Exploration Rovers (MER) Spirit (Gusev Crater) and Opportunity (Meridiani Planum) have each analyzed more than 100 targets during their ongoing missions (>1050 sols). Here we summarize the Fe-bearing phases identified to date and compare the results to Moessbauer analyses of martian meteorites and lunar samples. We use lunar samples as martian analogues because some, particularly the low-Ti Apollo 15 mare basalts, have bulk chemical compositions that are comparable to basaltic martian meteorites [1,2]. The lunar samples also provide a way to study pigeonite-rich samples. Pigeonite is a pyroxene that is not common in terrestrial basalts, but does often occur on the Moon and is present in basaltic martian meteorites
Klingelhoefer, G.↗
Working Group Reports and Presentations: Mars Science and Exploration
In Mars, the spirit of exploring an exciting and rewarding new frontier is alive. Mars not only offers a unique destination for exploration, but it is also a critical destination for the advancement of human society and preservation of humanity. The exploration of Mars will provide significant social and technological benefits to enhance life on Earth as well. International cooperation will not only be essential to the success of a human presence on Mars, but development of such interactions will jumpstart collaboration on global issues. The eventual commercialization of space holds tremendous opportunities for economic growth. Finally, there is an undeniable basic human need to explore and define our place in the universe. The overarching theme that ties together all of these reasons for exploration is to inspire and unite the global community to pursue a common cause that is much larger than disagreements over ethnic differences or national borders. Continuous inspiration of the public, the scientific community, and the community of Earth are required in order to explore Mars.
Beaty, David↗
Chemistry of Martian Soils from the Mars Exploration Rover APXS Instruments
The martian surface is covered with debris formed by several mechanisms and mobilized by various processes. Volcanism, impact, physical weathering and chemical alteration combine to produce particles of sizes from dust to boulders composed of primary mineral and rock fragments, partially altered primary materials, alteration minerals and shock-modified materials from all of these. Impacts and volcanism produce localized deposits. Winds transport roughly sand-sized material over intermediate distances, while periodic dust storms deposit a global dust layer of the finest fraction. The compositions of clastic sediments can be used to evaluate regional differences in crustal composition and/or weathering processes. Here we examine the growing body of chemical data on soils in Gusev crater and Meridiani Planum returned by the Alpha Particle X-ray Spectrometer (APXS) instruments on the rovers Spirit (MERA) and Opportunity (MERB), following on earlier results based on smaller data sets [1-4].
Mittlefehldt, D. W.↗
Geomorphic and Aqueous Chemistry of a Portion of the Upper Rio Tinto System, Spain
Observations from the two Mars rovers, Spirit and Opportunity, combined with discoveries of extensive hydrated sulfate deposits from OMEGA and CRISM show that aqueous deposition and alteration involving acidic systems and sulfate deposition has been a key contributor to the martian geologic record. Rio Tinto, Spain, provides a process model for formation of sulfates on Mars by evaporation of acidic waters within shallow fluvial pools, particularly during dry seasons. We present results from a detailed investigation of an upper portion of the Rio Tinto, focusing on geomorphology, clastic sediment transport, and acidic aqueous processes. We also lay out lessons-learned for under-standing sulfate formation and alteration on Mars.
Osburn, M. R.↗
The Solar Spectrum on the Martian Surface and its Effect on Photovoltaic Performance
Solar cells operating on the surface of Mars receive a spectrum of illumination different from the AM0 spectrum, since the sunlight is filtered by dust suspended in the atmosphere. This spectrum changes with the amount of dust in the atmosphere, as well as with air mass change due to time of day and season. This spectral variation affects the performance of solar cells. We used data from Mars Exploration Rovers to measure this spectrum. By comparing the measured intensity with the known reflectance of the pancam calibration target on the rovers Spirit and Opportunity, we measure the solar spectrum reaching the surface. The effect of this spectrum on the performance of solar cells is then calculated based on the spectral response of several different solar cell types.
Landis, Geoffrey A.↗
Composition and Formation of the "Paso Robles" Class Soils at Gusev Crater
Light-toned, subsurface soil deposits have been excavated by the Mars Exploration Rover (MER) Spirit in six distinct locations along its traverse across the Columbia Hills of Gusev Crater. Samples at two of these sites have been analyzed in detail by the M ssbauer (MB) and Alpha Particle X-ray Spectrometers (APXS), providing information on iron mineralogy and elemental chemistry, respectively. These soils are referred to as "Paso Robles" class deposits.
Yen, A. S.↗
NASA's Software Safety Standard
NASA relies more and more on software to control, monitor, and verify its safety critical systems, facilities and operations. Since the 1960's there has hardly been a spacecraft launched that does not have a computer on board that will provide command and control services. There have been recent incidents where software has played a role in high-profile mission failures and hazardous incidents. For example, the Mars Orbiter, Mars Polar Lander, the DART (Demonstration of Autonomous Rendezvous Technology), and MER (Mars Exploration Rover) Spirit anomalies were all caused or contributed to by software. The Mission Control Centers for the Shuttle, ISS, and unmanned programs are highly dependant on software for data displays, analysis, and mission planning. Despite this growing dependence on software control and monitoring, there has been little to no consistent application of software safety practices and methodology to NASA's projects with safety critical software. Meanwhile, academia and private industry have been stepping forward with procedures and standards for safety critical systems and software, for example Dr. Nancy Leveson's book Safeware: System Safety and Computers. The NASA Software Safety Standard, originally published in 1997, was widely ignored due to its complexity and poor organization. It also focused on concepts rather than definite procedural requirements organized around a software project lifecycle. Led by NASA Headquarters Office of Safety and Mission Assurance, the NASA Software Safety Standard has recently undergone a significant update. This new standard provides the procedures and guidelines for evaluating a project for safety criticality and then lays out the minimum project lifecycle requirements to assure the software is created, operated, and maintained in the safest possible manner. This update of the standard clearly delineates the minimum set of software safety requirements for a project without detailing the implementation for those requirements. This allows the projects leeway to meet these requirements in many forms that best suit a particular project's needs and safety risk. In other words, it tells the project what to do, not how to do it. This update also incorporated advances in the state of the practice of software safety from academia and private industry. It addresses some of the more common issues now facing software developers in the NASA environment such as the use of Commercial-Off-the-Shelf Software (COTS), Modified OTS (MOTS), Government OTS (GOTS), and reused software. A team from across NASA developed the update and it has had both NASA-wide internal reviews by software engineering, quality, safety, and project management. It has also had expert external review. This presentation and paper will discuss the new NASA Software Safety Standard, its organization, and key features. It will start with a brief discussion of some NASA mission failures and incidents that had software as one of their root causes. It will then give a brief overview of the NASA Software Safety Process. This will include an overview of the key personnel responsibilities and functions that must be performed for safety-critical software.
Ramsay, Christopher M.↗
[Now, The Time for Probes and In-Situ Science]
A viewgraph explaining the need for probes and in situ measurements to understand data from extra solar planet studies is shown. The topics include: 1) To explore the universe and search for life: Probes in Context; 2) What is a probe?; 3) NASA Ames Research Center-founded 1939; 4) Past & Present: Successful Probes and Fly-by's; 5) Thermal Protection Materials and Arc-Jet Facility; 6) Mars Exploration Rovers-Spirit & Opportunity; 7) Bio/Info/Nanotechnology; 8) Technology for Exploration; 9) Award Winning NASA Research Park; 10) Where we need to go; and 11) The Future: Pico Probes
Hubbard, G. Scott↗
Lavoisier: A Low Altitude Balloon Network for Probing the Deep Atmosphere and Surface of Venus
The in-situ exploration of the low atmosphere and surface of Venus is clearly the next step of Venus exploration. Understanding the geochemistry of the low atmosphere, interacting with rocks, and the way the integrated Venus system evolved, under the combined effects of inner planet cooling and intense atmospheric greenhouse, is a major challenge of modern planetology. Due to the dense atmosphere (95 bars at the surface), balloon platforms offer an interesting means to transport and land in-situ measurement instruments. Due to the large Archimede force, a 2 cubic meter He-pressurized balloon floating at 10 km altitude may carry up to 60 kg of payload. LAVOISIER is a project submitted to ESA in 2000, in the follow up and spirit of the balloon deployed at cloud level by the Russian Vega mission in 1986. It is composed of a descent probe, for detailed noble gas and atmosphere composition analysis, and of a network of 3 balloons for geochemical and geophysical investigations at local, regional and global scales.
Chaasefiere, E.↗
Iron Mineralogy and Aqueous Alteration on Mars from the MER Moessbauer Spectrometers
The twin Mars Exploration Rovers Spirit (Gusev crater) and Opportunity (Meridiani Planum) used MIMOS II Moessbauer spectrometers to analyze martian surface materials in the first application of extraterrestrial Moessbauer spectroscopy. The instruments acquired spectra that identified the speciation of Fe according to oxidation state, coordination state, and mineralogical composition and provided quantitative information about the distribution of Fe among oxidation states, coordination states, and Fe-bearing phases. A total of 12 unique Fe-bearing phases were identified: Fe(2+) in olivine, pyroxene, and ilmenite; Fe(2+) and Fe(3+) in magnetite and chromite; Fe(3+) in nanophase ferric oxide (npOx), hematite, goethite, jarosite, an unassigned Fe3+ sulfate, and an unassigned Fe(3+) phase associated with jarosite; and Fe(0) in kamacite. Weakly altered basalts at Gusev crater (SO3 = 2.5 +/- 1.4 wt.% and Fe(3+)/Fe(sub T) = 0.24 +/- 0.11) are widespread on the Gusev plains and occur in less abundance on West Spur and Husband Hill in the Columbia Hills. Altered low-S rocks (SO3 = 5.2 +/- 2.0 wt.% and Fe(3+)/Fe(sub T) = 0.63 +/- 0.18) are the most common type of rock in the Columbia Hills. Ilm-bearing, weakly altered basalts were detected only in the Columbia Hills, as was the only occurrence of chromite in an altered low-S rock named Assemblee. Altered high-S rocks (SO3 > 14.2 wt.% and Fe(3+)/Fe(sub T) = 0.83 +/- 0.05) are the outcrop rocks of the ubiquitous Burns formation at Meridiani Planum. Two Fe(0)-bearing rocks at Meridiani Planum (Barberton and Heat Shield Rock) are meteorites. Laguna Class soil is weakly altered (SO3 = 6 +/- 2 wt.% and Fe(3+)/Fe(sub T) = 0.29 +/- 0.08) and widely distributed at both Gusev crater and Meridiani Planum, implying efficient global mixing processes or a global distribution of precursor rocks with comparable Fe mineralogical compositions. Paso Robles Class soil is heavily altered (SO3 approx. 31 wt.% and Fe(3+)/Fe(sub T) = 0.83 +/- 0.05), is relatively uncommon, and occurs as subsurface deposits in the Columbia Hills. Berry Class soil is also heavily altered (SO3 = 5 +/- 1 wt.% and Fe(3+)/Fe(sub T) = 0.60 +/- 0.13) and occurs at Meridiani Planum as lag deposits, at the crests of aeolian bedforms, and as isolated pockets on outcrop surfaces. Magnetite is identified as the strongly magnetic component in martian soil. Jarosite (in the Burns outcrop at Meridiani Planum) and goethite (in Clovis Class rocks at Gusev crater) are mineralogical markers for aqueous processes because they contain the hydroxide anion (OH(-)) as an essential part of their structure. Each yields approx.10 wt.% H2O upon dehydroxylation. The presence of Fe sulfates on opposite sides of Mars is evidence that aqueous processes under acid sulfate conditions are or were common. Except for Independence Class rocks in the Columbia Hills, the overall Fe mineralogical compositions and similar basaltic bulk chemical compositions (calculated with respect to S = Cl = 0) of the population of altered rocks analyzed by MER imply isochemical alteration of basaltic precursors at low water-to-rock ratios.
Morris, Richard V.↗
Mars Exploration Rover Pancam Multispectral Imaging of Rocks, Soils, and Dust at Gusev Crater and Meridiani Planum
Multispectral imaging from the Panoramic Camera (Pancam) instruments on the Mars Exploration Rovers Spirit and Opportunity has provided important new insights about the geology and geologic history of the rover landing sites and traverse locations in Gusev crater and Meridiani Planum. Pancam observations from near-UV to near-IR wavelengths provide limited compositional and mineralogic constraints on the presence abundance, and physical properties of ferric- and ferrous-iron bearing minerals in rocks, soils, and dust at both sites. High resolution and stereo morphologic observations have also helped to infer some aspects of the composition of these materials at both sites. Perhaps most importantly, Pancam observations were often efficiently and effectively used to discover and select the relatively small number of places where in situ measurements were performed by the rover instruments, thus supporting and enabling the much more quantitative mineralogic discoveries made using elemental chemistry and mineralogy data. This chapter summarizes the major compositionally- and mineralogically-relevant results at Gusev and Meridiani derived from Pancam observations. Classes of materials encountered in Gusev crater include outcrop rocks, float rocks, cobbles, clasts, soils, dust, rock grindings, rock coatings, windblown drift deposits, and exhumed whitish/yellowish salty soils. Materials studied in Meridiani Planum include sedimentary outcrop rocks, rock rinds, fracture fills, hematite spherules, cobbles, rock fragments, meteorites, soils, and windblown drift deposits. This chapter also previews the results of a number of coordinated observations between Pancam and other rover-based and Mars-orbital instruments that were designed to provide complementary new information and constraints on the mineralogy and physical properties of martian surface materials.
Bell, J. F., III↗
Possible Evidence for Iron Sulfates, Iron Sulfides, and Elemental Sulfur at Gusev Crater, Mars, from Mer, Crism, and Analog Data
The Mossbauer (MB) spectrometers on the Mars Exploration Rovers (MER) Spirit (Gusev crater) and Opportunity (Meridiani Planum) have detected 14 Fe-bearing phases, and mineralogical assignments have been made for all except 3. Identified Fe2+-bearing phases are olivine, pyroxene, ilmenite, and troilite. Magnetite and chromite are present as mixed Fe(2+) and Fe(3+) phases. Identified Fe(3+) phase are jarosite, hematite, goethite, and nanophase ferric oxide (npOx). Fe(sup 0) (iron metal) is present as kamacite. Nanophase ferric oxide (npOx) is a generic name for octahedrally coordinated Fe(3+) alteration products that cannot be otherwise mineralogically assigned on the basis of MER data. On the Earth, npOx would include ferrihydrite, iddingsite, schwertmannite, akaganeite, and superparamagnetic hematite and goethite. The Mars Reconnaissance Orbiter CRISM instrument, a visible, near-IR hyperspectral imager (approximately 0.35 to 4 micron) enables mineralogical examination of Mars with a tool that is sensitive to H2O and to M-OH (M = Al, Si, Fe, Mg, etc.) at spatial resolution of about 20 m/pixel. We examined a CRISM image of the MER region of Gusev crater (Columbia Hills and plains to the west), looking for spectral evidence of the aqueous process apparent from the MER analyses. We also searched for spectral constraints for the mineralogical composition of our unidentified Fe-bearing phases and the forms of npOx present on Mars. We also consider evidence from analogue samples that the precursor for the goethite detected by MB in Clovis Class rocks is an iron sulfide. We suggest that there is some indirect evidence that elemental sulfur might be present to different extents in Clovis Class rocks, the Fe3Sulfate-rich soils, and perhaps even typical (Laguna Class) surface soils.
Morris, R. V.↗