81 Matching Results

Search Results

Advanced search parameters have been applied.

Exploring the Moon and Mars: Choices for the Nation

Description: This report, the result of an assessment of the potential for automation and robotics technology to assist in the exploration of the Moon and Mars, raises a number of issues related to the goals of the U.S. civilian space program. Among other things, the report discusses how greater attention to automation and robotics technologies could contribute to U.S. space exploration efforts.
Date: July 1991
Creator: United States. Congress. Office of Technology Assessment.
Partner: UNT Libraries Government Documents Department

In situ neutron spectroscopy on the martian surface: modeling the hydra instrument for different mission scenarios

Description: Neutron spectroscopy has proven to be highly successful in remotely detecting and measuring the abundance of water on planetary surfaces such as Mars and the Moon. Because of the central role played by water on Mars and the need to make in situ measurements of water abundances for landed missions, neutron spectroscopy is being investigated as a technique for quickly determining the near-surface water abundance for fhture Mars missions, such as the Mars Smart Larider (MSL).
Date: January 1, 2003
Creator: Lawrence, David J. (David Jeffery),; Elphic, R. C. (Richard C.); Feldman, W. C. (William C.); Moore, K. R. (Kurt R.); Prettyman, T. H. (Thomas H.) & Weins, R. C. (Roger C.)
Partner: UNT Libraries Government Documents Department

Effects of an RTG power source on neutron spectroscopy measurements on the martian surface.

Description: A continuing goal of Mars science is to identify the exact locations of near-surface water and/or hydrated minerals using in situ measurements. Recent data from the Mars Odyssey mission has used both neutron and gamma-ray spectroscopy to measure large amounts of water ice near both polar regions . Furthermore, these data have also determined that in the mid-latitude regions, there likely exist relatively large amounts of hydrogen (-4-7 equivalent H2O wt.%), although it is not certain in which form this hydrogen exists . While these are exciting results, one drawback of these measurements is that they are averaged over a large (-400 km) footp ri nt and do not reflect any small (<1 km) inhomogenieties in hydrogen abundance that likely exist on the Martian surface. For any future in situ mission (e g, Mars Smart Lander (MSL)) that seeks to measure and characterize nearsurface H 2O, especially in the mid-latitude regions, is will be necessary to know th e locati ons of the H20.
Date: January 1, 2003
Creator: Lawrence, David J. (David Jeffery),; Elphic, R. C. (Richard C.) & Wiens, R. C. (Roger C.)
Partner: UNT Libraries Government Documents Department

Capabilities of LIBS for analysis of geological samples at stand-off distances in a Mars atmosphere

Description: The use of LIBS for stand-off elemental analysis of geological and other samples in a simulated Mars atmosphere is being evaluated. Analytical capabilities, matrix effects, and other factors effecting analysis are being determined. Through funding from NASA's Mars Instrument Development Program (MIDP), we have been evaluating the use of LIBS for future use on landers and rovers to Mars. Of particular interest is the use of LIBS for stand-off measurements of geological samples up to 20 meters from the instrument. Very preliminary work on such remote LIBS measurements based on large laboratory type equipment was carried out about a decade ago. Recent work has characterized the capabilities using more compact instrumentation and some measurements have been conducted with LIBS on a NASA rover testbed.
Date: January 1, 2002
Creator: Cremers, D. A. (David A.); Wiens, R. C. (Roger C.); Ferris, M. J. (Monty J.); Brennetot, R. (Rene) & Maurice, S. (Sylvestre)
Partner: UNT Libraries Government Documents Department

Emissivity spectrum of a large "dark streak" from themis infrared imagery

Description: 'Dark streaks', also known as 'slope streaks', are unusual surface features found on Mars that are known to appear and fade away on timescales of years. Various explanations have been proposed for their origin and composition, including dry avalanches and wet debris or precipitates from brines. Previous investigations have been based on analysis of panchromatic imagery and altimetry from Viking and Mars Global Surveyor missions. We have obtained an infrared emissivity spectrum of a large dark streak on the north western edge of Olympus Mons, using imagery from the THEMIS instrument on the Mars Odyssey 2001 spacecraft.
Date: January 1, 2003
Creator: Brumby, Steven P.; Vaniman, D. T. (David T.) & Bish, D. L. (David L.)
Partner: UNT Libraries Government Documents Department

Basalt weathering rates on Earth and the duration of liquid water on the plains of Gusev Crater, Mars

Description: Where Martian rocks have been exposed to liquid water, chemistry versus depth profiles could elucidate both Martian climate history and potential for life. The persistence of primary minerals in weathered profiles constrains the exposure time to liquid water: on Earth, mineral persistence times range from {approx}10 ka (olivine) to {approx}250 ka (glass) to {approx}1Ma (pyroxene) to {approx}5Ma (plagioclase). Such persistence times suggest mineral persistence minima on Mars. However, Martian solutions may have been more acidic than on Earth. Relative mineral weathering rates observed for basalt in Svalbard (Norway) and Costa Rica demonstrate that laboratory pH trends can be used to estimate exposure to liquid water both qualitatively (mineral absence or presence) and quantitatively (using reactive transport models). Qualitatively, if the Martian solution pH > {approx}2, glass should persist longer than olivine; therefore, persistence of glass may be a pH-indicator. With evidence for the pH of weathering, the reactive transport code CrunchFlow can quantitatively calculate the minimum duration of exposure to liquid water consistent with a chemical profile. For the profile measured on the surface of Humphrey in Gusev Crater, the minimum exposure time is 22 ka. If correct, this estimate is consistent with short-term, episodic alteration accompanied by ongoing surface erosion. More of these depth profiles should be measured to illuminate the weathering history of Mars.
Date: March 15, 2008
Creator: Steefel, Carl; Hausrath, E. M.; Navarre-Sitchler, A. K.; Sak, P. B.; Steefel, C. & Brantley, S. L.
Partner: UNT Libraries Government Documents Department

Propulsion engineering study for small-scale Mars missions

Description: Rocket propulsion options for small-scale Mars missions are presented and compared, particularly for the terminal landing maneuver and for sample return. Mars landing has a low propulsive {Delta}v requirement on a {approximately}1-minute time scale, but at a high acceleration. High thrust/weight liquid rocket technologies, or advanced pulse-capable solids, developed during the past decade for missile defense, are therefore more appropriate for small Mars landers than are conventional space propulsion technologies. The advanced liquid systems are characterize by compact lightweight thrusters having high chamber pressures and short lifetimes. Blowdown or regulated pressure-fed operation can satisfy the Mars landing requirement, but hardware mass can be reduced by using pumps. Aggressive terminal landing propulsion designs can enable post-landing hop maneuvers for some surface mobility. The Mars sample return mission requires a small high performance launcher having either solid motors or miniature pump-fed engines. Terminal propulsion for 100 kg Mars landers is within the realm of flight-proven thruster designs, but custom tankage is desirable. Landers on a 10 kg scale also are feasible, using technology that has been demonstrated but not previously flown in space. The number of sources and the selection of components are extremely limited on this smallest scale, so some customized hardware is required. A key characteristic of kilogram-scale propulsion is that gas jets are much lighter than liquid thrusters for reaction control. The mass and volume of tanks for inert gas can be eliminated by systems which generate gas as needed from a liquid or a solid, but these have virtually no space flight history. Mars return propulsion is a major engineering challenge; earth launch is the only previously-solved propulsion problem requiring similar or greater performance.
Date: September 12, 1995
Creator: Whitehead, J.
Partner: UNT Libraries Government Documents Department

Mars ascent propulsion on a minimum scale

Description: A concept is presented for a single stage vehicle intended to lift a Mars sample to an orbital rendezvous. At 200 kg liftoff mass, it can potentially be delivered by a Mars Pathfinder size aeroshell. Based on launch vehicle design principles, propellants are pumped from thin-walled low pressure tanks into compact high pressure thrusters. Technical risk is reduced by using non-cryogenic propellants, and by driving piston pumps with heated helium.
Date: March 3, 1998
Creator: Whitehead, J.C. & Guernsey, C.S.
Partner: UNT Libraries Government Documents Department

Formation of magnetite and iron-rich carbonates by thermophilic iron-reducing bacteria

Description: Laboratory experiments were performed to study the formation of iron minerals by a thermophilic (45 to 75 C) fermentative iron-reducing bacterial culture (TOR39) obtained from the deep subsurface. Using amorphous Fe(III) oxyhydroxide as an electron acceptor and glucose as an electron donor, TOR39 produced magnetite and iron-rich carbonates at conditions consistent, on a thermodynamic basis, with Eh ({minus}200 mV to {minus}415 mV) and pH (6.2 to 7.7) values determined for these experiments. Analyses of the precipitating solid phases by X-ray diffraction showed that the starting amorphous Fe(III) oxyhydroxide was nearly completely converted to magnetite and Fe-rich carbonate after 20 days of incubation. Increasing bicarbonate concentration in the chemical milieu resulted in increased proportions of siderite relative to magnetite and the addition of MgCl{sub 2} caused the formation of magnesium-rich carbonate in addition to siderite. The results suggest that the TOR39 bacterial culture may have the capacity to form magnetite and iron-rich carbonates in a variety of geochemical conditions. These results may have significant implications for studying the past biogenic activities in the Martian meteorite ALH84001.
Date: June 1, 1997
Creator: Zhang, C.; Liu, S.; Roh, Y.; Cole, D.; Phelps, T.; Vali, H. et al.
Partner: UNT Libraries Government Documents Department

Mars Pathfinder airbag impact attenuation system

Description: The Mars Pathfinder spacecraft, scheduled for launch in November 1996, is designed to validate a low cost Entry, Descent, and Landing system and to perform scientific surface operations. The Jet Propulsion Laboratory and Sandia National Laboratories teamed to design, fabricate, test and validate a prototype 0.38 scale model of an airbag impact attenuation system. A computer code was developed to predict the performance of the airbag system. A test program in Sandia`s High Altitude Chamber was performed to validate the code and demonstrate the feasibility of the airbag concept and design. In addition, freefall tests were performed at representative velocities to demonstrate the structural integrity of the airbag system design. The feasibility program demonstrated that the airbag impact attenuation design will protect the lander upon impact with the Martian surface.
Date: April 1, 1995
Creator: Waye, D.E.; Cole, J.K. & Rivellini, T.P.
Partner: UNT Libraries Government Documents Department

Precision flyer initiator

Description: A propulsion point design is presented for lifting geological samples from Mars. Vehicle complexity is kept low by choosing a monopropellant single stage. Little new development is needed, as miniature pump fed hydrazine has been demonstrated. Loading the propellant just prior to operation avoids structural, thermal, and safety constraints otherwise imposed by earlier mission phases. hardware mass and engineering effort are thereby diminished. The Mars liftoff mass is 7/8 hydrazine, <5% propulsion hardware, and >3% each for the payload and guidance.
Date: April 19, 1999
Creator: Frank, A
Partner: UNT Libraries Government Documents Department

Development of an ultracompact neutron spectrometer for identifying near-surface water on mars.

Description: One of the major goals of the Mars science program is to identify exact locations of near-surface water or hydrated minerals on Mars. Evidence is mounting that Mars may have contemporary near-surface groundwater activity. Though very water-poor by terrestrial igneous standards, the SNC meteorivtes were found to contain evaporite minerals suggestive of groundwater activity within the past 1.3 Ga. More recently, the Mars Surveyor camera recorded images of geologically young seepage and outflow channels attributed to liquid water. The sources of these channels were suggested to be only a few hundred meters or less below the surface. If these channels are truly geologically young, thinly buried ice may still exist at the termination of these channels.
Date: January 1, 2001
Creator: Lawrence, David J. (David Jeffery); Wiens, R. C. (Roger C.); Moore, K. R. (Kurt R.) & Prettyman, T. H. (Thomas H.)
Partner: UNT Libraries Government Documents Department

Can hydrous minerals account for the observed mid-latitude water on Mars?

Description: Great interest was generated with the discovery by the Odyssey spacecraft OC heterogeneously distributed hydrogcn at martian mid-latitudes, suggesting that large areas of the near-equatorial highlands contain near-surface deposits of 'chemically and/or physically bound 1120 and/or OH' in amounts up to 3.8% equivalent H20. More recent interpretations of the Odyssey data using new calibrations suggest that some near-equatorial areas, such as Arabia Terra, contain up to 8.5f I .3% water-equivalent hydrogen. Such shallow occurrences (<I tn) of H20 ice near the martian equator are particularly enigmatic because H20 ice is not stable at these latitudes. A number of potentially hydrous silicate phases, notably clay minerals and zeolites, have been proposed as possible M20-bearing constituents on Mars, and both groups of minerals are common terrestrial alteration products of hydrovolcanic basaltic ashes and palagonitic material comparable io those that may be widespread on Mars. Smectites within martian meteorites, attributed to hydrous alteration on Mars rather than on Earth, provide direct evidence of clay minerals from Mars. In addition, new thermal emission spectrometer (TES) data provide evidence for unspecified zeolites in martian surface dust, and concluded that spectral deconvolution of MGS TES and Mariner 9 IRIS data is consistent with the presence of zeolite in the martian surface dust.
Date: January 1, 2003
Creator: Bish, D. L. (David L.); Vaniman, D. T. (David T.); Fialips, C. I. (Clair I.); Carey, J. W. (James W.) & Feldman, W. C. (William C.)
Partner: UNT Libraries Government Documents Department

Single-grain optical dating properties of JSC Mars-1: preliminary measurements of radiation dose response and sensitivity change.

Description: Martian surface deposits, including polar deposits, represent a vast storehouse of data recording the evolution Of Mars' climate and surface environment. However, the greatest challenge to deciphering these martian geo-records is the need for absolute dating techniques, Particularly those techniques applicable to the timeframes and surface processes of the 'Martian Quaternary'. Lepper and McKeever [3,4] have proposed developing optical dating, an established terrestrial chronometric dating method based on principles eri'solid-state physics, for retnote in-situ dating oCrnartian surface seditnents.
Date: January 1, 2003
Creator: Lepper, K. E. (Kenneth E.)
Partner: UNT Libraries Government Documents Department

Neutron sensors for locating sites of planetary water deposits

Description: This is the final report of a six-month, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). This project helped in exploration of the value and feasibility of use of collimated neutron detection methods for improving the sensitivity of neutron spectrometers specifically designed for deep-space missions to detect and identify both present-day deposits of near-surface water ice. The authors believed that this result helped enable a decision to include a Los Alamos-designed neutron sensor as a component of the NASA Mars Global Surveyor-01 Gamma-Ray/Neutron Spectrometer.
Date: December 31, 1998
Creator: Feldman, W.C.; Fenimore, E.E.; Byrd, R.C. & Wiens, R.C.
Partner: UNT Libraries Government Documents Department

Integrated reentry and penetrator vehicle (IRPV) for subsurface soil collection and analysis on Mars

Description: The continued exploration of Mars is a high priority item with NASA`s interplanetary science community. It has long been a desire of this group to define an experiment that would investigate the possible presence and location of water/ice beneath the Martian surface. Until recently, however, there has not been a flight experiment dedicated to achieving this goal. This paper describes a concept design effort conducted at Sandia National Labs in collaboration with JPL and CalTech that has produced a feasible flight system to investigate this question.
Date: August 1, 1996
Creator: Keese, D.L. & Lundgren, R.
Partner: UNT Libraries Government Documents Department

Anti-matter propulsion: feasibility, status, and possible enhancement

Description: The possible use of advanced propulsion techniques must be considered if the currently envisioned launch date of the Manned Mars Mission were to be delayed until 2020 or later. Within the next 30 years, technological advances may allow such methods as beaming power to the ship, inertial-confinement fusion, or mass-conversion of anti-protons to become feasible. Of the possible methods, the anti-proton (anti p), reaction offers the highest potential, the greastest problems, and the most fascination. An Isp of 5000 s would allow the currently envisioned ship to fly to Mars in 3 months and would require about one million pounds to be assembled in Earth orbit. Anti-protons are currently being produced in the world in amounts of about 10/sup 14/ particles per year. With sufficient effort, almost a mg/yr (6 x 10/sup 20/) could be produced by the early 2000s. Current experiments plan to decelerate and capture about 10/sup 10/ or greater anti-protons in an electrostatic Penning trap. Such traps may provide a source of low energy anti p's for development of better storage mechanisms suitable for propulsion. Recently, proposals have been investigated which would amplify the average energy released per anti p used. The proposals entail using the anti p's to produce inertial confinement fusion of a capsule or to produce negative muons which can catalyze fusion. By increasing the energy released per anti p, the effective specific cost, $/joule, can be reduced to attractive levels. These two proposals and other areas of research can be investigated now and will help in assessing the feasibility of an anti p engine.
Date: January 1, 1985
Creator: Howe, S.D.
Partner: UNT Libraries Government Documents Department

Mars base buildup scenarios

Description: Two surface base build-up scenarios are presented in order to help visualize the mission and to serve as a basis for trade studies. In the first scenario, direct manned landings on the Martian surface occur early in the missions and scientific investigation is the main driver and rationale. In the second scenario, early development of an infrastructure to exploite the volatile resources of the Martian moons for economic purposes is emphasized. Scientific exploration of the surface is delayed at first, but once begun develops rapidly aided by the presence of a permanently manned orbital station.
Date: January 1, 1985
Creator: Blacic, J.D.
Partner: UNT Libraries Government Documents Department

Fiber optic chemical sensors on Mars

Description: A fiber optic chemical sensing instrument is described that will measure the reactivity of the martian soil and atmosphere. The self- contained instrument monitors reflectivity changes in reactive thin films caused by chemical reactions with the martian soil or atmosphere. Data from over 200 separate thin-film-coated optical fibers are recorded simultaneously. This fiber optic sensing technology has many advantages for planetary exploration and monitoring applications on manned spacecraft, in addition to many practical terrestrial uses.
Date: December 31, 1993
Creator: Butler, M. A.; Ricco, A. J.; Grunthaner, F. J. & Lane, A. L.
Partner: UNT Libraries Government Documents Department

Development and testing of laser-induced breakdown spectroscopy for the Mars Rover Program : elemental analysis at stand-off distances

Description: One of the most Fundamental pieces of information about any planetary body is the elemental cornposition of its surface materials. The Viking Martian landers employed XRF (x-ray fluorescence) and the MER rovers are carrying APXS (alpha-proton x-ray spectrometer) instruments upgraded from that used on the Pathfinder rover to supply elemental composition information for soils and rocks for which direct contact is possible. These in-situ analyses require that the lander or rover be in contact with the sample
Date: January 1, 2003
Creator: Cremers, D. A. (David A.); Wiens, R. C. (Roger C.); Arp, Z. A. (Zane A.); Harris, R. D. (Ronny D.) & Maurice, S. (Sylvestre)
Partner: UNT Libraries Government Documents Department

Quantitative laser-induced breakdown spectroscopy data using peak area step-wise regression analysis: an alternative method for interpretation of Mars science laboratory results

Description: The ChemCam instrument on the Mars Science Laboratory (MSL) will include a laser-induced breakdown spectrometer (LIBS) to quantify major and minor elemental compositions. The traditional analytical chemistry approach to calibration curves for these data regresses a single diagnostic peak area against concentration for each element. This approach contrasts with a new multivariate method in which elemental concentrations are predicted by step-wise multiple regression analysis based on areas of a specific set of diagnostic peaks for each element. The method is tested on LIBS data from igneous and metamorphosed rocks. Between 4 and 13 partial regression coefficients are needed to describe each elemental abundance accurately (i.e., with a regression line of R{sup 2} > 0.9995 for the relationship between predicted and measured elemental concentration) for all major and minor elements studied. Validation plots suggest that the method is limited at present by the small data set, and will work best for prediction of concentration when a wide variety of compositions and rock types has been analyzed.
Date: January 1, 2008
Creator: Clegg, Samuel M; Barefield, James E; Wiens, Roger C; Dyar, Melinda D; Schafer, Martha W & Tucker, Jonathan M
Partner: UNT Libraries Government Documents Department