Engineering topics

Chapman, M. G.

Publications and source records attributed to Chapman, M. G..

8 records

NASA NTRS2009

Science Operations for the 2008 NASA Lunar Analog Field Test at Black Point Lava Flow, Arizona

Surface science operations on the Moon will require merging lessons from Apollo with new operation concepts that exploit the Constellation Lunar Architecture. Prototypes of lunar vehicles and robots are already under development and will change the way we conduct science operations compared to Apollo. To prepare for future surface operations on the Moon, NASA, along with several supporting agencies and institutions, conducted a high-fidelity lunar mission simulation with prototypes of the small pressurized rover (SPR) and unpressurized rover (UPR) (Fig. 1) at Black Point lava flow (Fig. 2), 40 km north of Flagstaff, Arizona from Oct. 19-31, 2008. This field test was primarily intended to evaluate and compare the surface mobility afforded by unpressurized and pressurized rovers, the latter critically depending on the innovative suit-port concept for efficient egress and ingress. The UPR vehicle transports two astronauts who remain in their EVA suits at all times, whereas the SPR concept enables astronauts to remain in a pressurized shirt-sleeve environment during long translations and while making contextual observations and enables rapid (less than or equal to 10 minutes) transfer to and from the surface via suit-ports. A team of field geologists provided realistic science scenarios for the simulations and served as crew members, field observers, and operators of a science backroom. Here, we present a description of the science team s operations and lessons learned.

Garry W. D.↗

NASA NTRS2009

Santorini, Another Meteorite on Mars and Third of a Kind

The Mars Exploration Rover (MER) Opportunity has been studying Meridiani Planum for five years. On sol 1634 of its mission, Opportunity left Victoria crater after investigating it for approximately 682 sols [1] and is now on a journey towards Endeavour, a 24 km diameter crater about 12 km southeast of Victoria. A priority along the way is the investigation of cobbles, which in the jargon of the MER science team denotes any loose rock fragment larger than a couple of centimeters. Cobbles investigated thus far are of diverse origin [2] and provide the only means to investigate material other than the ubiquitous sulfate-rich outcrop, basaltic sand or hematiterich spherules dubbed blueberries. Some of these cobbles are meteorites [3]. Meteorites on Mars are not just a curiosity that make Mars a more Earth-like planet. Metallic iron in meteorites, for example, may be used as a more sensitive tracer for volatile surface interactions compared to igneous minerals [4]. Between sols 1713 and 1749, including the period of Mars solar conjunction, Opportunity investigated a cobble informally named Santorini. Its chemical and mineralogical composition is very similar to Barberton and Santa Catarina, two cobbles that were identified as meteorites and which are probably related to each other [3]. Santorini was investigated with the rover s Panoramic Camera (Pancam), Microscopic Imager (MI), Alpha-Particle X-ray Spectrometer (APXS) and Moessbauer (MB) spectrometer. The miniature Thermal Emission Spectrometer (mini-TES) was not operational at the time. The Rock Abrasion Tool (RAT) could not be used to brush off potential dust coatings because of unfavorable geometry.

Schroeder, C.↗

NASA NTRS1999

Potential 2001 Landing Sites in Melas Chasma, Mars

We have selected four areas in Valles Marineris as potential landing sites for the 2001 mission. After 20 years of analyses, the formation of the Valles Marineris system of troughs and its associated deposits still has not been sufficiently explained. They could have formed by collapse, as tectonic grabens, or in two stages involving ancestral collapse basins later cut by grabens. Understanding all aspects of the Valles Marineris, in particular the interior layered deposits, would significantly contribute to deciphering the internal and external history of Mars. The deposits have been postulated to be remnants of wall rock, lacustrine deposits, mass wasting deposits, eolian deposits, carbonate deposits, or volcanic deposits. Because an understanding of the formation of Valles Marineris and its interior deposits is so important to deciphering the history of Mars, we have proposed landing sites for the 2001 mission on flat shelves of interior deposits in Melas Chasma.

Weitz, C. M.↗

NASA NTRS1993

Evidence for an ice sheet/frozen lake in Utopia Planitia, Mars

Previous workers noted evidence for a lacustrine basin in Utopia Planitia, Mars. Geomorphic features within the basin that collectively suggest that water or ice may once have been present include channels within the basin, channels peripheral to the basin, etched basin floor, 'thumbprint' terrain (whorled patterns), polygonal outlines, smooth floors (infilled), shoreline indicators (terraces, platforms, lineaments), and small cratered cones (pseudo craters or pingos). The authors interpret these data to suggest that the basin may have been the locus of a large paleolake in the northern lowlands of Mars. Alternatively, the area was proposed to be part of an ancient circumpolar ocean. The hypothetical paleolake was probably frozen to some depth. In fact, features now present at its boundaries suggest that the edges may have been frozen solid. Plains units at the southwestern boundary of Utopia Planitia show ridges that were compared with those that form at the mouths of Antarctic ice streams, thumbprint terrain, and young, high deposits having lobate margins that suggest mudflows. Thumbprint terrains were interpreted as recessional moraines, ice-pushed ridges, or subglacially eroded tunnel valleys with eroded eskers. At the east boundary of Utopia Planitia, geologic mapping at 1:500,000 scale of the Granicus Valles area (MTM quadrangles 30227, 30222, and 25227) indicates the presence of a basal scarp around the northwest flank of Elysium that formed the east boundary of an ancient ice sheet.

Chapman, M. G.↗

NASA NTRS1991

Mars Elysium Basin - Geologic/volumetric analysis of a young lake and exobiologic implications

Geologic, physiographic, and topographic data on the Elysium Basin on the Martial lowland plains are used to determine the former volume of water in the basin and the sources of this water. The maximum extent of the paleolake was estimated to be about 2,000,000 sq km, with a water volume of 850,000 cu km or more, supplied to the basin from many sources in the highlands via inflow channels. The climatic and biological implications that the Elysium-Basin sea or lake might have had are discussed.

Scott, D. H.↗

NASA NTRS1989

Geologic setting of an unusual Martian channel - Hypotheses on origin

Several areas within the Memnonia region of Mars have been proposed as candidate sites for a Mars sample return mission. Geologic studies of these areas made from computer-enhanced high-resolution Viking images show that an assemblage of rocks having different ages and compositions are accessible to a roving vehicle. In addition, evidence of recent fluvial episodes is indicated by small channels that incises materials emplaced during the Amazonian Period. The channel discussed in this paper is located near the highland-lowland boundary in the Memnonia MC-16SW quadrangle of Mars. It is of particular interest because of distinctive morphologic characteristics compared to other Martian channels. Although several hypotheses are advanced to explain the origin of the channel, none of the arguments are completely satisfactory. However, it is believed that water mobilized from ice in the subjacent regolith (hypothesis 1) or that condensate water from highly volatile ash flows (hypothesis 2) are the most likely origins for the channel.

Scott, D. H.↗

NASA NTRS1988

Search for Mars lander/rover/sample-return sites: A status review

Ten Mars sites were studied in the USA for four years. The sites are the Chasma Boreale (North Pole), Planum Australe (South Pole), Olympus Rupes, Mangala Valles, Memnonia Sulci, Candor Chasma, Kasel Valles, Nilosyrtis Mensae, Elysium Montes, and Apollinaris Patera. Seven sites are being studied by the USSR; their prime sites are located at the east mouth of Kasel Valles and near Uranius Patera. Thirteen geological maps of the first six USA sites are compiled and in review. Maps of the Mangala East and West sites at 1:1/2 million scale and a 1:2 million scale map show evidence of three episodes of small-channel formation interspersed with episodes of volcanism and tectonism that span the period from 3.5 to 0.6 b.y. ago. The tectonic and geological history of Mars, both ancient and modern, can be elucidated by sampling volcanic and fluvial geologic units at equatorial sites and layered deposits at polar sites. The evidence appears clear for multiple episodes of fluvial channeling, including some that are quite recent; this evidence contrasts with the theses of Baker and Partridge (1986) and many others that all channels are ancient. Verification of this hypothesis by Mars Observer will be an important step forward in the perception of the history of Mars.

Masursky, Harold↗

NASA NTRS1987

Martian terrains

Terrain studies of candidate landing sites for a future rover/sample-return mission to Mars are being conducted to evaluate the geologic and trafficability aspects of each site. An optimum site should have geologic units of widely diverse ages and chemical compositions occurring in close enough proximity and in smooth enough terrain so that a roving vehicle of limited traverse ability (+ or - 100 km) could collect representative samples. In FY 1986, geologic maps were compiled at 1:500,000 and 1:2 million scales of the Mangala Valles, Kasei Valles, Chasma Boreale (north polar), and Planum Australe (south polar) areas, and a study was begun of the topography and surface roughness characteristics of the Mangala Valles site. Geologic mapping has been greatly facilitated by specially enhanced, high-resolution Viking photographs, which clarify stratigraphic relations of units unrecognized earlier. Photoclinometric profiles of topographic features provide width and depth measurements of four classes of channels, the thickness of some volcanic units, and the throw on some faults. Estimates of the surface roughness of units are calculated using a newly developed USGS computer program and using measurements derived from Earth-based radar.

Masursky, Harold↗