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NASA NTRS2014

MSL Entry, Descent, and Landing Instrumentation: Return on Investment

On Aug 5, 2012 the Mars Science Laboratory (MSL) Entry, Descent, and Landing Instrumentation (MEDLI) suite on MSL entry vehicle heatshield suc-cessfully returned surface pressure and in-depth temperature data.1,2 The MEDLI data has given scientists and engineers an unprecedented ability to reconstruct entry environment, atmospheric density, and flight trajectory, and flight validation of predic-tions vehicle aerodynamics and thermal protection system (TPS) performance. This presentation will dis-cuss key findings from MEDLI, some of which are being applied to improve definition of aerothermal environment and TPS sizing margins for existing NASA entry missions. The postflight analysis has shown that a significant thermal protection mass saving upon redesign is possible for an MSL-class vehicle. The success of MEDLI has also demonstrated and qualified robust flight instrumentation technologies at very low risk to the mission. The potential benefits of MEDLI to planetary exploration and sample return missions, as well as to exploration class missions to Mars will be presented.

MEDLI↗

NASA NTRS2017

Physical Properties of the Stone Meteorites: Implications for the Properties of Their Parent Bodies

The physical properties of the stone meteorites provide important clues to understanding the formation and physical evolution of material in the Solar protoplanetary disk as well providing indications of the properties of their asteroidal parent bodies. Knowledge of these properties is essential for modeling a number of Solar System processes, such as bolides in planetary atmospheres, the thermal inertia of atmosphereless solid body surfaces, and the internal physical and thermal evolution of asteroids and rock-rich icy bodies. In addition, insight into the physical properties of the asteroids is important for the design of robotic and crewed reconnaissance, lander, and sample return spacecraft missions to the asteroids. One key property is meteorite porosity, which ranges from 0% to more than 40%, similar to the range of porosities seen in asteroids. Porosity affects many of the other physical properties including thermal conductivity, speed of sound, deformation under stress, strength, and response to impact. As a result of the porosity, the properties of most stone meteorites differ significantly from those of compact terrestrial rocks, whose physical properties have been used in many models of asteroid behavior. A few physical properties, such as grain density, magnetic susceptibility, and heat capacity are not functions of porosity. Taken together, the grain density and the magnetic susceptibility can be used to classify unweathered or minimally weathered ordinary chondrites. This provides a rapid screening technique to identify heterogeneous samples, classify new samples, and identify misclassified meteorites or interlopers in strewn fields.

Chondritic meteorites↗

NASA NTRS1992

A Combined XRD/XRF Instrument for Lunar Resource Assessment

Robotic surface missions to the Moon should be capable of measuring mineral as well as chemical abundances in regolith samples. Although much is already known about the lunar regolith, our data are far from comprehensive. Most of the regolith samples returned to Earth for analysis had lost the upper surface, or it was intermixed with deeper regolith. This upper surface is the part of the regolith most recently exposed to the solar wind; as such it will be important to resource assessment. In addition, it may be far easier to mine and process the uppermost few centimeters of regolith over a broad area than to engage in deep excavation of a smaller area. The most direct means of analyzing the regolith surface will be by studies in situ. In addition, the analysis of the impact-origin regolith surfaces, the Fe-rich glasses of mare pyroclastic deposits, are of resource interest, but are inadequately known; none of the extensive surface-exposed pyroclastic deposits of the Moon have been systematically sampled, although we know something about such deposits from the Apollo 17 site. Because of the potential importance of pyroclastic deposits, methods to quantify glass as well as mineral abundances will be important to resource evaluation. Combined x ray diffraction (XRD) and x ray fluorescence (XRF) analysis will address many resource characterization problems on the Moon. XRF methods are valuable for obtaining full major-element abundances with high precision. Such data, collected in parallel with quantitative mineralogy, permit unambiguous determination of both mineral and chemical abundances where concentrations are high enough to be of resource grade. Collection of both XRD and XRF data from a single sample provides simultaneous chemical and mineralogic information. These data can be used to correlate quantitative chemistry and mineralogy as a set of simultaneous linear equations, the solution of which can lead to full characterization of the sample. The use of Rietveld methods for XRD data analysis can provide a powerful tool for quantitative mineralogy and for obtaining crystallographic data on complex minerals.

Vaniman, D. T.↗

NASA NTRS2017

Pulmonary Inflammatory Responses To Acute Meteorite Dust Exposures - Implications For Human Space Exploration

The previous manned missions to the Moon represent milestones of human ingenuity, perseverance, and intellectual curiosity. However, one of the major ongoing concerns is the array of hazards associated with lunar surface dust. Not only did the dust cause mechanical and structural integrity issues with the suits, the dust 'storm' generated upon reentrance into the crew cabin caused "lunar hay fever" and "almost blindness" (Figure 1). It was further reported that the allergic response to the dust worsened with each exposure. The lack of gravity exacerbated the exposure, requiring the astronauts to wear their helmet within the module in order to avoid breathing the irritating particles. Due to the prevalence of these high exposures, the Human Research Roadmap developed by NASA identifies the Risk of Adverse Health and Performance Effects of Celestial Dust Exposure as an area of concern. Extended human exploration will further increase the probability of inadvertent and repeated exposures to celestial dusts. Going forward, hazard assessments of celestial dusts will be determined through sample return efforts prior to astronaut deployment. Studies on the lunar highland regolith indicate that the dust is not only respirable but also reactive, and previous studies concluded that it is moderately toxic; generating a greater response than titanium oxide but a lower response than quartz. The presence of reactive oxygen species (ROS) on the surface of the dust has been implicated. However, there is actually little data related to physicochemical characteristics of particulates and pulmonary toxicity, especially as it relates to celestial dust exposure. As a direct response to this deficit, the present study evaluates the role of a particulate's innate geochemical features (e.g., bulk chemistry, internal composition, morphology, size, and reactivity) in generating adverse toxicological responses in vitro and in vivo. This highly interdisciplinary study evaluates the relative toxicity of six meteorite samples representing either basalt or regolith breccia on the surfaces of the Moon, Mars, and Asteroid 4Vesta; three potential candidates for future human exploration or colonization. Terrestrial mid-ocean ridge basalt (MORB) is also used for comparison as a control sample.

Harrington, A. D.↗

NASA NTRS2011

Integration of In-Flight and Post-Flight Water Monitoring Resources in Addressing the U.S. Water Processor Assembly Total Organic Carbon (TOC) Anomaly

Beginning in June of 2010, the total organic carbon (TOC) concentration in the U.S. Water Processor Assembly (WPA) product water started to increase. A surprisingly consistent upward TOC trend was observed through weekly ISS total organic carbon analyzer (TOCA) monitoring. As TOC is a general organic compound indicator, return of water archive samples was needed to make better-informed crew health decisions on the specific compounds of concern and to aid in WPA troubleshooting. TOCA-measured TOC was more than halfway to the health-based screening limit of 3,000 g/L before archive samples were returned. Archive samples were returned on 22 Soyuz in September 2010 and on ULF5 in November of 2010. The samples were subjected to extensive analysis. Although TOC was confirmed to be elevated, somewhat surprisingly, none of the typical target compounds were detected at high levels. After some solid detective work, it was confirmed that the TOC was associated with a compound known as dimethylsilanediol (DMSD). DMSD is believed to be a breakdown product of siloxanes which are thought to be ubiquitous in the ISS atmosphere. A toxicological limit was set for DMSD and a forward plan was developed for conducting operations in the context of understanding the composition of the TOC measured in flight. This required careful consideration of existing ISS flight rules, coordination with ISS stakeholders, and development of a novel approach for the blending of inflight TOCA data with archive results to protect crew health. Among other challenges, team members had to determine how to utilize TOCA readings when making decisions about crew consumption of WPA water. This involved balancing very real concerns associated with the assumption that TOC would continue to be comprised of only DMSD. Demonstrated teamwork, multidisciplinary awareness, and innovative problem-solving were required to respond effectively to this anomaly.

Straub, John E., II↗

NASA NTRS2000

Scouts: Using Numbers to Explore Mars In Situ

Mars is a planet with a complex geologic history involving fluvial, volcanic, aeolian, atmospheric, and impact processes. Many critical questions about Mars are still heatedly debated within the scientific community and we still have much to discover. The current Mars exploration philosophy involves remote observation of the planet from orbit and intensive in situ study of a few sites on the surface. Orbital data provides a global picture while in situ investigations provide detailed knowledge at a single location. Mars Scouts are proposed to provide access to multiple locations on Mars. They address the emerging program needs of exploring the diversity of the planet globally in ways that cannot be achieved from orbit. The goal of the Scout is to find a way to investigate many locations on the surface of Mars in an affordable and efficient manner. We have only visited three locations on the surface of Mars, which have very similar characteristics. Increased numbers allows more types of locations to be investigated. The hallmarks of Scouts are numbers and access. Thus the capability of a single Scout will be limited. The science return from a single Scout will be significantly less than from a large science lander or an orbiting spacecraft. Scouts rely on their numbers to collectively provide a substantial increase in our knowledge of Mars. Scouts potentially serve two purposes in the Mars exploration architecture. First, Scouts are a science exploration tool. They provide access to places on Mars we currently can't explore because program focus, surface roughness, elevation, or latitude that we know are scientifically interesting. Scouts can react to new discoveries and evolving ideas about Mars. They can be used to test theories which until proven would not warrant the investment of a large lander. Second, Scouts enable better large scale missions by providing ground truth of remote sensing data and allowing us to "know" sites in advance before sending large landers and sample return missions. This increases the probability of success for these expensive missions both from safety and science return stand-points.

Blaney, D. L.↗

NASA NTRS1991

Determination of lunar ilmenite abundances from remotely sensed data

The mineral ilmenite (FeTiO3) was found in abundance in lunar mare soils returned during the Apollo project. Lunar ilmenite often contains greater than 50 weight-percent titanium dioxide (TiO2), and is a primary potential resource for oxygen and other raw materials to supply future lunar bases. Chemical and spectroscopic analysis of the returned lunar soils produced an empirical function that relates the spectral reflectance ratio at 400 and 560 nm to the weight percent abundance of TiO2. This allowed mapping of the lunar TiO2 distribution using telescopic vidicon multispectral imaging from the ground; however, the time variant photometric response of the vidicon detectors produced abundance uncertainties of at least 2 to 5 percent. Since that time, solid-state charge-coupled device (CCD) detector technology capable of much improved photometric response has become available. An investigation of the lunar TiO2 distribution was carried out utilizing groundbased telescopic CCD multispectral imagery and spectroscopy. The work was approached in phases to develop optimum technique based upon initial results. The goal is to achieve the best possible TiO2 abundance maps from the ground as a precursor to lunar orbiter and robotic sample return missions, and to produce a better idea of the peak abundances of TiO2 for benefaction studies. These phases and the results are summarized.

Larson, Stephen M.↗

NASA NTRS2017

Acute Meteorite Dust Exposure and Pulmonary Inflammation - Implications for Human Space Exploration

The previous manned missions to the Moon represent milestones of human ingenuity, perseverance, and intellectual curiosity. However, one of the major ongoing concerns is the array of hazards associated with lunar surface dust. Not only did the dust cause mechanical and structural integrity issues with the suits, the dust 'storm' generated upon reentrance into the crew cabin caused "lunar hay fever" and "almost blindness [1-3]" (Figure 1). It was further reported that the allergic response to the dust worsened with each exposure [4]. The lack of gravity exacerbated the exposure, requiring the astronauts to wear their helmet within the module in order to avoid breathing the irritating particles [1]. Due to the prevalence of these high exposures, the Human Research Roadmap developed by NASA identifies the Risk of Adverse Health and Performance Effects of Celestial Dust Exposure as an area of concern [5]. Extended human exploration will further increase the probability of inadvertent and repeated exposures to celestial dusts. Going forward, hazard assessments of celestial dusts will be determined through sample return efforts prior to astronaut deployment. Studies on the lunar highland regolith indicate that the dust is not only respirable but also reactive [2, 6-9], and previous studies concluded that it is moderately toxic; generating a greater response than titanium oxide but a lower response than quartz [6]. The presence of reactive oxygen species (ROS) on the surface of the dust has been implicated. However, there is actually little data related to physicochemical characteristics of particulates and pulmonary toxicity, especially as it relates to celestial dust exposure. As a direct response to this deficit, the present study evaluates the role of a particulate's innate geochemical features (e.g., bulk chemistry, internal composition, morphology, size, and reactivity) in generating adverse toxicological responses in vitro and in vivo. This highly interdisciplinary study evaluates the relative toxicity of six meteorite samples representing either basalt or regolith breccia on the surfaces of the Moon, Mars, and Asteroid 4Vesta (Table 1); three potential candidates for future human exploration or colonization. Terrestrial mid-ocean ridge basalt (MORB) is also used for comparison as a control sample.

Harrington, A. D.↗

NASA NTRS2012

Relay Support for the Mars Science Laboratory and the Coming Decade of Mars Relay Network Evolution

In the past decade, an evolving network of Mars relay orbiters has provided telecommunication relay services to the Mars Exploration Rovers, Spirit and Opportunity, and to the Mars Phoenix Lander, enabling high-bandwidth, energy-efficient data transfer and greatly increasing the volume of science data that can be returned from the Martian surface, compared to conventional direct-to-Earth links. The current relay network, consisting of NASA's Odyssey and Mars Reconnaissance Orbiter and augmented by ESA's Mars Express Orbiter, stands ready to support the Mars Science Laboratory, scheduled to arrive at Mars on Aug 6, 2012, with new capabilities enabled by the Electra and Electra-Lite transceivers carried by MRO and MSL, respectively. The MAVEN orbiter, planned for launch in 2013, and the ExoMars/Trace Gas Orbiter, planned for launch in 2016, will replenish the on-orbit relay network as the current orbiter approach their end of life. Currently planned support scenarios for this future relay network include an ESA EDL Demonstrator Module deployed by the 2016 ExoMars/TGO orbiter, and the 2018 NASA/ESA Joint Rover, representing the first step in a multimission Mars Sample Return campaign.

MAVEN↗

NASA NTRSDate not supplied

Lessons Learned from Aerothermal Flight Data on NASA Mars Entry Vehicles

The NASA Mars Science Laboratory (MSL) and Mars 2020 entry vehicles included temperature measurements inside and direct heat flux on the surface of the thermal protection system (TPS) material. The instrumentation was included to begin addressing predictive capabilities for aerodynamic heating and ablative TPS material response. The MSL aeroshell included temperature measurements at seven heatshield locations, from which total aerodynamic heating was reconstructed. The Mars 2020 instrumentation suite included eleven heatshield measurement locations and new backshell measurements at nine locations: six with temperature sensors, two with sensors to directly measure total heat flux, and one to measure radiative heat flux. Both instrumentation suites returned full sets of data, with all temperature sensors nearest to the surface surviving entry, indicating minimal material recession. Heatshield boundary layer transition (BLT) was observed for both vehicles prior to the time of peak heating, with transition starting near the shoulder and progressing towards the stagnation area. MSL’s higher speed on approach to Mars resulted in higher total heating compared to Mars 2020, with the maximum occurring near the heatshield’s leeside shoulder. The Mars 2020 backshell heating data indicate significant contributions from shock layer radiation. Heating from Navier-Stokes flowfield calculations are in family with reconstructed heating. The paper covers the instrumentation, BLT and reconstructed heating on both heatshields, backshell heating for Mars 2020, TPS performance, and predicted versus reconstructed heat fluxes. Opportunities for improved design approaches for future Mars missions are discussed, especially for the upcoming Mars Sample Return mission.

Mars Science Laboratory↗

NASA NTRSDate not supplied

Lessons Learned from Aerothermal Flight Data on NASA Mars Entry Vehicles

Mars Science Laboratory↗

NASA NTRS1998

Biomarkers in Carbonate Thermal Springs: Implications for Mars

Evidence of possible relict biogenic activity has been reported in carbonate inclusions within martian meteorite ALH 84001. The initial evidence included ovoid and elongated forms 50 - 500 nanometers in length, morphologically similar to but significantly smaller than many terrestrial microbes. More recently, thin structures resembling the remains of organic biofilms have been reported in the same meteorite. Carbonates have also been discussed in the context of Mars sample return missions. Thermal spring deposits have often been cited as prime locations for exobiological exploration. By analogy to Earth, specialized microbes may have existed in the heated, mineralized waters, and precipitates of carbonate and/or silica from these waters may have trapped and preserved evidence of life. Since the geological interactions that produce thermal springs can be recognized in orbital imagery, directed searches for microfossils in such deposits are deemed possible. We are engaged in a study of the signatures produced by contemporary biogenic activity (biomarkers) in carbonate thermal springs. We are examining the microbes that live in such environments and the preservation of microbial forms, biofilms, and petrographic fabrics indicative of life in thermal spring mineral deposits. This work is part of a much more extensive study to refine the appropriate tools, techniques, and approaches to seek evidence of life in a range of planetary samples. A deeper understanding of biological signatures will prepare us for the detailed search for life on Mars and eventually on other planets. Overall. the study of biomarkers in rocks and soils will provide insight into the evolution of life because such signatures are a record of how life interacts with its environment, how it adapts to changing conditions, and how life can influence geology and climate.

Allen, C. C.↗

NASA NTRS2009

Understanding the Activation and Solution Properties of Lunar Dust for Future Lunar Habitation

The decision to return humans to the moon by 2020 makes it imperative to understand the effects of lunar dust on human and mechanical systems.( Bush 2004; Gaier 2005; Mendell 2005) During the Apollo missions, dust was found to cause numerous problems for various instruments and systems. Additionally, the dust may have caused health issues for some of the astronauts.(Gaier 2005; Rowe 2007) It is necessary, therefore, for studies to be carried out in a variety of disciplines in order to mitigate the effects of the dust as completely as possible. Due to the lack of an atmosphere, there is nothing to protect the lunar soil from ultraviolet radiation, solar wind, and meteorite impacts. These processes could all serve to "activate" the soil, or produce reactive surface species. In order to understand the possible toxic effects of the reactive dust, it is necessary to "reactivate" the dust, as samples returned during the Apollo missions were exposed to the atmosphere of the Earth. We have used grinding and exposure to UV radiation in order to mimic some of the processes occurring on the lunar surface. To monitor the reactivity of the dust, we have measured the ability of the dust to produce hydroxyl radicals in solution. These radicals have been measured using a novel fluorescent technique developed in our laboratory,(Wallace et al. 2008) as well as using electron paramagnetic resonance (EPR).

Wallace, William T.↗

NASA NTRSDate not supplied

Ramdb: The NASA Raman Spectral Database (version 1.00).

Given that, in most instances, minimal sample preparation is required and due to its contactless instrument design, Raman spectroscopy is one of the most versatile vibrational spectroscopic techniques for the chemical analysis of environmental and biological specimens. The diversity of applications of Raman spectroscopy ranges anywhere from art [1] to planetary science missions [2]. The advancement in the use of Raman spectroscopy in Solar System missions, notably in post-mission sample return analysis, requires a spectral library holding the broad range of specimens that could be found in Solar System sources. For this purpose, we have initiated the development of a Raman spectral database (Ramdb) at NASA Ames Research Center. Currently, the database includes experimental and theoretical Raman spectra of PAHs [3, 4], as well as laboratory Raman spectra of amino acids, carbon allotropes, minerals, and analogs relevance to Earth Sciences [5], Exobiology [6], Planetary [7], and Astrochemistry [8] to name just a few examples. Ramdb can be found on the web at www.astrochemistry.org/ramdb, where raw and processed Raman spectra can be downloaded in CSV format. The laboratory Raman spectra are measured using a laser Raman spectrometer (JASCO NRS-5500-532QRI). The Raman instrument is equipped with three excitation lasers, with wavelengths of 405, 532, and 785 nm. A clean silicon substrate is used as the internal standard for wavenumber calibration. Powdered samples were prepared (microscopic >10 um, grounded microscopic < 10 um) on glass slides. Some raw data exhibited a background signal arising as a combination of laser-induced fluorescence from the sample. To correct this background, we developed a Python pipeline that uses open-source Python libraries. Ramdb provides both raw and processed (using Python pipeline) data, which includes tabulated Raman shift transitions and other measurement details. The theoretical Raman band positions of PAHs (pyrene monomers and tetramer clusters) were computed using density functional theory (DFT) with the help of the Gaussian 16 suite of programs [9]. In the near future, Ramdb will serve as a repository of Raman spectral data from Laboratory Astrophysics and Planetary Science experiments involving the irradiation of organic compounds under simulated space and planetary conditions. In addition, online and offline tools will be developed for utilising the database for comparison to the user’s sample.

N Punnakayathil↗

DOE OSTI2020

A New Method for Deriving Composition of S-type Asteroids from Noisy and Incomplete Near-infrared Spectra

The surface composition of S-type asteroids can be determined using band parameters extracted from their near-infrared (NIR) spectra (0.7–2.50 μm) along with spectral calibrations derived from laboratory samples. In the past, these empirical equations have been obtained by combining NIR spectra of meteorite samples with information about their composition and mineral abundance. For these equations to give accurate results, the characteristics of the laboratory spectra they are derived from should be similar to those of asteroid spectral data (i.e., similar signal-to-noise ratio (S/N) and wavelength range). Here we present new spectral calibrations that can be used to determine the mineral composition of ordinary chondrite-like S-type asteroids. Contrary to previous work, the S/N of the ordinary chondrite spectra used in this study has been decreased to recreate the S/N typically observed among asteroid spectra, allowing us to obtain more realistic results. In addition, the new equations have been derived for five wavelength ranges encompassed between 0.7 and 2.50 μm, making it possible to determine the composition of asteroids with incomplete data. The new spectral calibrations were tested using band parameters measured from the NIR spectrum of asteroid (25143) Itokawa, and comparing the results with laboratory measurements of the returned samples. We found that the spectrally derived olivine and pyroxene chemistry, which are given by the molar contents of fayalite (Fa) and ferrosilite (Fs), are in excellent agreement with the mean values measured from the samples (Fa{sub 28.6±1.1} and Fs{sub 23.1±2.2}), with a maximum difference of 0.6 mol% for Fa and 1.4 mol% for Fs.

79 ASTRONOMY AND ASTROPHYSICS↗

NASA NTRS2013

Microbial Monitoring of Common Opportunistic Pathogens by Comparing Multiple Real-Time PCR Platforms for Potential Space Applications

Because the International Space Station is a closed environment with rotations of astronauts and equipment that each introduce their own microbial flora, it is necessary to monitor the air, surfaces, and water for microbial contamination. Current microbial monitoring includes labor- and time-intensive methods to enumerate total bacterial and fungal cells, with limited characterization, during in-flight testing. Although this culture-based method is sufficient for monitoring the International Space Station, on future long-duration missions more detailed characterization will need to be performed during flight, as sample return and ground characterization may not be available. At a workshop held in 2011 at NASA's Johnson Space Center to discuss alternative methodologies and technologies suitable for microbial monitoring for these long-term exploration missions, molecular-based methodologies such as polymerase chain reaction (PCR) were recommended. In response, a multi-center (Marshall Space Flight Center, Johnson Space Center, Jet Propulsion Laboratory, and Kennedy Space Center) collaborative research effort was initiated to explore novel commercial-off-the-shelf hardware options for space flight environmental monitoring. The goal was to evaluate quantitative or semi-quantitative PCR approaches for low-cost in-flight rapid identification of microorganisms that could affect crew safety. The initial phase of this project identified commercially available platforms that could be minimally modified to perform nominally in microgravity. This phase was followed by proof-of-concept testing of the highest qualifying candidates with a universally available challenge organism, Salmonella enterica. The analysis identified two technologies that were able to perform sample-to-answer testing with initial cell sample concentrations between 50 and 400 cells. In addition, the commercial systems were evaluated for initial flight safety and readiness.

Real time↗

NASA NTRS2002

WOBBLE: A Proposed Mission to Characterize Past and Present Water on Mars

WOBBLE ("Water Observations from a Balloon Borne Light Explorer") is a mission concept study for a small robotic probe to explore Mars and to accomplish a scientific mission compatible with the goals of the NASA Code S enterprise. The detection of past or present water is a crucial goal for Mars exploration, representing a cross-cutting science theme relevant to past or extant life, climate history, sample return missions and eventual human exploration. The WOBBLE mission concept was developed to study evidence of water using in-situ detection methods. The features on Mars most suited to this investigation are the gullies identified by Malin and Edgett as evidence for recent, near-surface runoff of liquid water. These features are typically located on the inside face of crater rims, where the local slope angle is at or near the angle of repose. This makes the terrain difficult or impossible to access with conventional wheeled rover technology. Combined with the small size of the gullies in relation to a standard landing error ellipse, scientific investigation of these features requires a new approach to surface mobility. WOBBLE uses a low-altitude balloon-borne platform to traverse the surface from the landing site, to the investigation site, and then rise up the slope to investigate the regions of interest at close range. Of the mobility technologies available for near-term Mars exploration, only a balloon platform is capable of a well targeted, detailed sampling of the gully regions over periods of days or more. The science approach embodied in WOBBLE is two-pronged, designed to investigate both the historical evidence of liquid water utilizing high-resolution geomorphology and the characterization of mineral deposits, and present subsurface liquid water using radar sounding techniques. The WOBBLE balloon is a high-pressure hydrogen gas design, 24 meters in diameter and lifting a total payload of 130 kg, including a high-resolution camera/IR imager, Raman spectrometer, and a ground penetrating radar (GPR) sounder. The stowed balloon and payload are designed to fit within the current airbag delivery system being built for the Mars Exploration Rovers. Characterization of local meteorological conditions and wind is made over the initial sols following landing and before balloon inflation. Following balloon inflation and launch, a controlled, targeted approach toward the identified regions of interest is made in a series of several low-altitude "hops," with the balloon tethered to the ground between the hop intervals. A "snake" system is used to control the altitude to a few tens of meters above the local ground level. Enroute to the target gully, GPR soundings and Raman spectroscopy measurements study past or present water, while continued camera bearings and meteorological measurements refine the next "hop" trajectory. Once at the gully/outflow region, GPR and Raman soundings continue while the camera obtains detailed, approx. 0.5 cm images for geomorphology studies. The WOBBLE concept is applicable to Mars Scout, Mars Surveyor, or Discovery class missions.

Udrea, Bogdan↗

NASA NTRS1995

A Simulated Geochemical Rover Mission to the Taurus-Littrow Valley of the Moon

We test the effectiveness of using an alpha backscatter, alpha-proton, X ray spectrometer on a remotely operated rover to analyze soils and provide geologically useful information about the Moon during a simulated mission to a hypothetical site resembling the Apollo 17 landing site. On the mission, 100 soil samples are "analyzed" for major elements at moderate analytical precision (e.g., typical relative sample standard deviation from counting statistics: Si[11%], Al[18%], Fe[6%], Mg[20%], Ca[5%]). Simulated compositions of soils are generated by combining compositions of components representing the major lithologies occurring at the site in known proportions. Simulated analyses are generated by degrading the simulated compositions according to the expected analytical precision of the analyzer. Compositions obtained from the simulated analyses are modeled by least squares mass balance as mixtures of the components, and the relative proportions of those components as predicted by the model are compared with the actual proportions used to generate the simulated composition. Boundary conditions of the modeling exercise are that all important lithologic components of the regolith are known and are represented by model components, and that the compositions of these components are well known. The effect of having the capability of determining one incompatible element at moderate precision (25%) is compared with the effect of the lack of this capability. We discuss likely limitations and ambiguities that would be encountered, but conclude that much of our knowledge about the Apollo 17 site (based on the return samples) regarding the distribution and relative abundances of lithologies in the regolith could be obtained. This success requires, however, that at least one incompatible element be determined.

Korotev, Randy L.↗