Mars Pathfinder

Barnouin-Jha, 0. Murchie, S. (2000) Rock coatings at the Mars Pathfinder landing site. 

D. W. Allen, C.C. Britt, D.T. (2000) Mineralogy, composition, and alteration of Mars Pathfinder rocks and sods Evidence from multispectral, elemental, and magnetic data on terrestrial analogue, SNC meteorite, and Pathfinder samples. J. Geophys. Res. 105 1757-1817... 

The Mars Pathfinder rover (flight spare) pictured with one of the Mars Exploration Rovers (MER) during assembly. 

The Mars Pathfinder rover carried an Alpha Proton X-ray Spectrometer (APXS), and the two Mars Exploration Rovers (MER - Spirit and Opportunity) carried Alpha Particle X-ray Spectrometers (also called APXS, but in this case more precise versions of the Pathfinder instrument, though without the ability to monitor protons for light element analyses). These instruments contained radioactive curium sources (Fig. 13.16) whose decay produced a-particles, which irradiated target rocks and soils. The resulting characteristic X-rays provided measurements of major and minor element abundances. The MER rovers also carried Mossbauer spectrometers, which yielded information on iron oxidation state. 

The composition of Martian surface materials can be assessed using laboratory analyses of Martian meteorites, in situ APXS analyses from Mars Pathfinder and the Mars Exploration Rovers, and orbital geochemistry analyzed by GRS and derived from TES spectra. 

Alkalis versus silica diagram used for geochemical classification of volcanic rocks. Martian meteorites, Gusev crater rocks and soils analyzed by the Spirit rover, and Bounce Rock analyzed by the Opportunity rover generally plot in the field of basalts, as does the average Mars Odyssey GRS analysis. Compositions derived from TES spectra (Surface Types 1 and 2) and the Mars Pathfinder dust-free rock plot in the basaltic andesite and andesite fields. After McSween et at. (2009). 

Global GRS maps of Mars, for (a) silicon, (b) iron, and (c) /Th. Letters represent spacecraft landing sites V1 and V2 Viking, PF Mars Pathfinder, M Merdiani (Opportunity), and G Gusev (Spirit). The line in (b) separates the southern highlands from the northern lowlands. White areas above 50° N and S were not analyzed. 

McSween, H. Y. and 14 coauthors (1999) Chemical, multispectral and textural constraints on the composition and origin of rocks at the Mars Pathfinder landing site. Journal of Geophysical Research, 104, 8679-8715. 

All Mars rovers to date have carried alpha-particle X-ray spectrometer (APXS) instruments for chemical analyses of rocks and soils (see Fig. 13.16). The source consists of radioactive curium, which decays with a short half-life to produce a-particles, which then irradiate the sample. Secondary X-rays characteristic of specific elements are then released and measured by a silicon drift detector. The Mars Pathfinder APXS also measured the backscattered a-particles, for detection of light elements, but the Mars Exploration Rovers measured only the X-rays. 

Catogan D., Sandy C., Grahne M., Development and evaluation of the Mars Pathfinder Inflatable Airbag Landing System Proc. 49th International Astro-nautical Congress, 1998. 

Aerogel is a special materials with extreme micron porosity. It consists of separate particles of several nanometers, interconnected in a high-porosity branched structure. It was made on the basis of gel consisting of colloid silicone, the structural parts of which are filled with solvents. Aerogel is subjected to high temperature under pressure which rises to the critical point it is very strong and easily endures stress both at lift-off and in the space environment. This material has already been tried in space by Spacelab II and Eureca shuttles, as well as by the American Mars Pathfinder Rover. 

The accepted mean density of Mars, based on its measured volume and determination of its mass from spacecraft orbits, is 3.9335 0.0004 g cm (Lodders and Fegley, 1998). The density of the elastic lithosphere (approximately equivalent to the crust), estimated from models of the relationship between gravity and topography from Mars Global Surveyor data, is 2.95-2.99 g cm (McKenzie et al., 2002), which is similar to the density of basalt. The planet s dimensionless moment of inertia (0.3662 0.0017), calculated from Mars Pathfinder measurement of the rate at which its spin pole precesses (Folkner et al., 1997), constrains the core radius to —1,300-1,500 km, depending on core composition. 

Viking landers carried out Rutherford back-scattering and X-ray fluorescence (XRF) analyses of soils at two sites (Clark et al., 1982). Rocks and soils were analyzed by an alpha-proton X-ray spectrometer (APXS) on the Mars Pathfinder rover (Rieder et al., 1997) (Figure 1). Early APXS analyses (Rieder et al., 1997 McSween... 

Figure 1 Mars Pathfinder rover performing an APXS analysis of a rock (Barnacle Bill).

Oxide Viking 1 soils Mars Pathfinder soils ... 

Source Wanke et al. (2001). Average error, in relative % applies to Mars Pathfinder roeks and soils. Source Clark et al. (1982). 

However, these meteorites are depleted in aluminum relative to terrestrial rocks, a characteristic shared by martian soils and the Mars Pathfinder dust-free rock (Figure 5). Ratios of volatile to refractory elements (e.g., K/La) are constant but higher than in terrestrial or lunar rocks (Figure 6). 

Bertka and Fei (1997) experimentally determined mantle mineral stabilities using the Wanke and Dreibus (1988) model composition. The mineral stability fields and resulting mantle density profile, as well as core densities and positions of the core-mantle boundary for a range of model core compositions, are illustrated in Figure 9. The moment of inertia calculated from these experimental data (0.354) is consistent with the Mars Pathfinder measurement (Bertka and Fei, 1998). However, this model requires an unrealistically thick crust. 

Figure 11 Chemical classification of martian volcanic rocks. Squares show basaltic materials in the southern highlands (surface 1) and andesitic materials in the northern lowlands (surface 2), derived from deconvolved TES spectra from Mars Global Surveyor (Hamilton et al., 2001). Analyzed compositions of the Mars Pathfinder dust-free rock (Wanke et al., 2001) and martian meteorites (basaltic shergottites are filled circles and nakhlites are...

The planetary CO2 inventory has been estimated from C/N ratios of possible accreted volatile sources (chondrites or comets). Carbon dioxide estimates, expressed as equivalent global thicknesses of carbonate, vary from 3 m to 20 m (Bogard et al., 2001). Carbonates have not been detected spectroscopically on Mars as of early 2000s, although they are present in small quantities as martian weathering products in SNC meteorites. Carbon in soils at the Mars Pathfinder site is below detection limit, and the visible inventory of carbon on Mars is only 10 that of Earth or Venus (Bogard et al., 2001). 

Bertka C. M. and Fei Y. (1998) Implications of Mars Pathfinder data for the accretion history of the terrestrial planets. Science 281, 1838-1840. 

Mars Pathfinder Marsupial cats Marsupial rats and mice... 

The Mars Pathfinder probe landed on Mars on July 4,1997. Pathfinder was second in the Discovery series of robotic spacecraft, which the United States National Aeronautics and Space Administration (NASA) began to develop in the mid 1990s. Costing an average of 150 million per project, the Discovery shift to faster, cheaper, less-ambitious probes was prompted by the catastrophic failure in 1993 of the 1-billion Mars Observer mission. Pathfinder was the third spacecraft ever to land successfully on Mars NASA s Viking I and Viking II spacecraft... 

Backshell—Upper shell of the Mars Pathfinder entry vehicle, enclosing the lander/rover vehicle along with the heat shield during the cruise and entry phases of the mission. Entry braking rockets are also mounted to the backshell. 

Golombek, M.P., et al. Overview of the Mars Pathfinder Mission and Assessment of Landing Site Predictions. Science 278, No. 5344 (December 5,1997) 1743-1748. 

Jet Propulsion Laboratory. Mars Pathfinder. National Aeronautics and Space Administration. July 6,1999 [cited November 23, 2002]. . 

Some of the equipment on the Mars Pathfinder, shown here in a NASA illustration, was powered by a curium battery. 

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