The geology of the Viking Lander 1 site

Abstract. We have mapped thermal inertia at high resolution for selected regions of Mars that are of potential biological relevance, using observations made by the Mars Global Surveyor Thermal Emission Spectrometer. Thermal inertia is a direct indicator of physical properties of the surface at the decimeter-to-meter scale. Our goal is to understand the geological processes by which the sites formed and their subsequent evolution, their current state, and their safety and science potential as landing sites for future lander, rover, and sample-return spacecraft missions. The thermal inertia values at -3-km scale for the sites considered span the entire range of values measured at Mars; thermal inertias range from low values indicative of substantial aeolian mantling up to high values suggesting surfaces covered predominantly with bedrock, exposed rocks or blocks, or wellindurated crusts. The highest thermal inertias correlate strongly with local morphology, while areas with intermediate and low thermal inertias generally show no such correlation. This suggests that selection of future landing sites will be plagued by a choice of a well-mantled site that is safe but less interesting scientifically versus an unmantied site that is more interesting scientifically but less safe.

Section: Geology Of the Viking Landing Sitesmentioning

confidence: 99%

High‐resolution thermal inertia mapping of Mars: Sites of exobiological interest

Jakosky¹,

Mellon²

2001

“…Obtaining such information in situ on a planetary surface requires a capable Raman spectrometer, a good means for its deployment, and that the surface of the rock be accessible. Dust was present on the rocks observed by the Pathfinder and Viking missions [Golornbek et al, 1997; Binder et al, 1977;Mutch et al, 1977]. This dust did not cover most rocks uniformly, and the sensor of the spectrometer could possibly be guided to a relatively dust-poor location.…”

Section: Mineral Proportionsmentioning

confidence: 99%

Raman spectroscopic characterization of a Martian SNC meteorite: Zagami

Wang¹,

Jolliff²,

Haskin³

1999

Abstract. To demonstrate the ability of Raman spectroscopy to determine the mineralogical character of a rock that originated on Mars, we analyzed a small slab of"normal Zagami" by point analyses and multipoint scans using laboratory spectrometers. Spectra of clinopyroxenes were dominant; their compositions were estimated from a calibration of Raman peak positions with Mg/•g+Fe) basexl on lunar pyroxenes of known composition, and these agree with compositions obtained by electron microprobe. A few spectra of orthopyroxene were observed. The broad specmun of maskelynite was observed, but not that of plagioclase feldspar. Spectra of minor phosphates, magnetite, and pyrrhofite were obtained, as were spectra of an organic contaminant and of hematite, both apparently introduced during sample handling prior to Raman analysis. The modal analysis based on the multipoint scans agrees well with published values. If the spectra had been obtained on the surface of Mars by Raman spectroscopic analysis as a stand-alone method and no other information about the sample was available (and by ignoring the spurious hematite and organic material), we could role out sedimentary and plutonic rock types and conclude that the sample was a pyroxene-phyric basalt.

“…On Mars, the rocks at the Viking 1 site are thought to be a partially covered and eroded lava flow surface, although ejecta from craters and flood deposits have also been suggested from the apparent diversity of rock types at this site [Binder et al, 1977]. Viking 2 rocks are likely ejecta from the nearby large crater Mie [Mutch et al, 1977].…”

Section: Earth and Mars Rock Size-frequency Distribution Relationshipsmentioning

confidence: 99%

Size‐frequency distributions of rocks on Mars and Earth analog sites: Implications for future landed missions

Golombek¹,

Rapp²

1997

163

226

Abstract. The size-frequency distribution of rocks at the Viking landing sites and a variety of rocky locations on the Earth that formed from a number of geologic processes all have the general shape of simple exponential curves, which have been combined with remote sensing data and models on rock abundance to predict the frequency of boulders potentially hazardous to future Mars landers and rovers. Rock data from the near field of the Viking landers where dimensions can be measured accurately in stereo images and estimates from the far field of Viking 1 have convex up curved shapes on log-log graphs of cumulative frequency per square meter or cumulative fractional area versus diameter. The rock data show a sharp drop-off at large diameters and a progressive approach to a plateau with decreasing diameter (approaching the total rock coverage), which can be fit well with simple exponential functions. Similar shaped size-frequency distributions of rocks are found at a wide variety of rocky surfaces on the Earth and can be fit well with simple exponential functions. This distribution is compatible with fracture and fragmentation theory, which provides a physical basis for its wide application. A combined fit to rock area data at both Viking sites was made with a general exponential function, in which the pre-exponential is the total area covered by rocks. Simple linear height versus dimneter relationships were also derived from height-diameter ratios at the Viking sites, which suggest that rockier areas on Mars have higher standing rocks than less rocky areas. Height was then substituted into the general exponential function derived for diameter, yielding the cumulative fractional area of rocks versus height for any given total rock coverage on Mars. Results indicate that most of Mars is rather benign with regard to hazards from landing on large rocks. For total rock coverage of 8%, equivalent to modal rock coverage on Mars and the Viking 1 site without the outcrops, about 1% of the surface is covered by 20 cm or higher rocks. A lander designed to accommodate landing on 0.5-m-high boulders, such as the Mars Pathfinder airbag system, could land on a surface covered by about 20% rocks, similar to the Viking 2 site (which is rockier than -95% of the planet), with -1% of the surface covered by rocks of 0.5 m or higher.