Selection of the Mars Pathfinder landing site

The Mars Pathfinder spacecraft will land on a depositional fan near the mouth of the catastrophic outflow channel, Ares Vallis (19.5°N, 32.8°W). This site offers the prospect of analyzing a variety of rock types from the ancient cratered highlands, intermediate-age ridged plains, and reworked channel deposits. Analyses of these rocks by Pathfinder instruments will enable first-order scientific questions to be addressed, such as differentiation of the crust, the development of weathering products, and the nature of the early environment, as well as their subsequent evolution on Mars. Constraints imposed by (1) spacecraft and rover designs (which are robust), (2) entry, descent, and landing, (3) scientific potential at various sites, and (4) safety were important considerations in site selection. Engineering constraints require a 70 km by 200 km smooth, flat (low slopes) area located between 10° and 20°N that is below 0 km elevation, with average radar reflectivity, little dust, and moderate rock abundance. Three regions on Mars are between 10° and 20°N and below 0 km elevation: Chryse, Amazonis, and Isidis-Elysium. Science considerations favor sites at the mouths of outflow channels (grab bag sites offer an assay of rock types on Mars), highland sites (early crustal differentiation and climate), and sites covered with dark (unoxidized) material. Sites are considered safe if they are clearly below 0 km elevation, appear acceptably free of hazards in high-resolution (<50 m/pixel) Viking orbiter images and have acceptable reflectivity and roughness at radar wavelengths, thermal inertia, rock abundance, red to violet ratio, and albedo. Recent 3.5-cm wavelength radar observations were used to verify elevation, reflectivity, and roughness within the landing ellipses. Three sites meet all of these criteria: Ares Vallis, Tritonis Lacus, and Isidis. Although Isidis appears to be safer than Tritonis and Ares, the greater scientific potential at Ares Vallis resulted in its selection. Comparisons of the Grand Coulee (channel) and the depositional Ephrata Fan of the Channeled Scabland in eastern Washington, with Ares Vallis and its depositional fan also suggest the Ares Vallis landing site is safe and scientifically interesting.

[1]  T. Hagfors,et al.  Backscattering from an undulating surface with applications to radar returns from the Moon , 1964 .

[2]  E. Opik,et al.  The Martian Surface , 1966, Science.

[3]  J. Ulrichs,et al.  Electrical properties of rocks and their significance for lunar radar observations , 1969 .

[4]  G. Leonard Tyler,et al.  Lunar slope distributions: Comparison of bistatic‐radar and photographic results , 1971 .

[5]  G. Neugebauer,et al.  Preliminary report on infrared radiometric measurements from the Mariner 9 spacecraft , 1973 .

[6]  V. Baker.  Paleohydrology and sedimentology of Lake Missoula flooding in eastern Washington , 1973 .

[7]  R. Shorthill,et al.  A comparison of infrared, radar, and geologic mapping of lunar craters , 1974 .

[8]  R. R. Green,et al.  Radar measurements of Martian topography and surface properties - The 1971 and 1973 oppositions , 1975 .

[9]  G. Olhoeft,et al.  Dielectric properties of the first 100 meters of the Moon , 1975 .

[10]  H. J. Moore,et al.  Radar Characteristics of Viking 1 Landing Sites , 1976, Science.

[11]  H. Masursky,et al.  The Viking Landing Sites: Selection and Certification , 1976, Science.

[12]  Terry Z. Martin,et al.  Thermal and albedo mapping of Mars during the Viking primary mission , 1977 .

[13]  Klaus Keil,et al.  Geochemical and mineralogical interpretation of the Viking inorganic chemical results , 1977 .

[14]  R. Greeley,et al.  Geology of Chryse Planitia , 1977 .

[15]  Kenneth L. Jones,et al.  The geology of the Viking Lander 1 site , 1977 .

[16]  D. Campbell,et al.  Arecibo radar observations of Mars surface characteristics in the northern hemisphere , 1978 .

[17]  P. E. Reichley,et al.  Radar studies of the Martian surface at centimeter wavelengths: The 1975 opposition , 1978 .

[18]  H. J. Moore,et al.  Lunar remote sensing and measurements , 1980 .

[19]  E. Miner,et al.  Time variability of Martian bolometric albedo , 1981 .

[20]  F. Palluconi,et al.  Thermal inertia mapping of Mars from 60°S to 60°N , 1981 .

[21]  G. Leonard Tyler,et al.  Viking bistatic radar experiment: Summary of first-order results emphasizing north polar data , 1981 .

[22]  P. Christensen,et al.  Martian dust mantling and surface composition: Interpretation of thermophysical properties , 1982 .

[23]  D. Campbell,et al.  Dual-polarization radar observations of Mars: Tharsis and Environs , 1982 .

[24]  Laurence A. Soderblom,et al.  Modeling crater topography and albedo from monoscopic Viking Orbiter images: 1. Methodology , 1984 .

[25]  G. Leonard Tyler,et al.  Viking Bistatic Radar Experiment: Summary of results in near-equatorial regions , 1984 .

[26]  Steven J. Ostro,et al.  Mars - Dual-polarization radar observations with extended coverage , 1985 .

[27]  B. Jakosky.  On the thermal properties of Martian fines , 1986 .

[28]  D. H. Scott,et al.  GEOLOGIC MAP OF THE WESTERN EQUATORIAL REGION OF MARS , 1986 .

[29]  Kenneth L. Tanaka.  The stratigraphy of Mars , 1986 .

[30]  B. Jakosky,et al.  Global duricrust on Mars: Analysis of remote‐sensing data , 1986 .

[31]  P. Christensen.  Regional dust deposits on Mars - Physical properties, age, and history , 1986 .

[32]  Philip R. Christensen,et al.  The spatial distribution of rocks on mars , 1986 .

[33]  Raymond E. Arvidson,et al.  On The spectral reflectance properties of materials exposed at the Viking landing sites , 1987 .

[34]  Ronald Greeley,et al.  Geologic map of the eastern equatorial region of Mars , 1987 .

[35]  Cary R. Spitzer,et al.  Physical properties of the surface materials at the Viking landing sites on Mars , 1987 .

[36]  R. Arvidson,et al.  Nature and distribution of surficial deposits in Chryse Planitia and vicinity, Mars , 1988 .

[37]  C. Weitz,et al.  Sand dune materials and polar layered deposits on Mars , 1989 .

[38]  H. J. Moore,et al.  Viking landing sites, remote-sensing observations, and physical properties of Martian surface materials , 1989 .

[39]  Raymond E. Arvidson,et al.  The Martian surface as imaged, sampled, and analyzed by the Viking landers , 1989 .

[40]  R. Haberle,et al.  Atmospheric effects on the remote determination of thermal inertia on mars , 1991 .

[41]  J. Keller,et al.  Surface-Material Maps of Viking Landing Sites on Mars , 1991 .

[42]  T. W. Thompson,et al.  A radar-echo model for Mars. , 1991 .

[43]  D. Muhleman,et al.  Radar Images of Mars , 1991, Science.

[44]  L. Soderblom.  The composition and mineralogy of the Martian surface from spectroscopic observations: 0.3 μm to 50 μm. , 1992 .

[45]  Virginia C. Gulick,et al.  Channels and valley networks. , 1992 .

[46]  D. Muhleman,et al.  Radar determination of Mars surface properties , 1992 .

[47]  J. Chandler,et al.  Mars radar mapping : strong backscatter from the Elysium basin and outflow channel , 1992 .

[48]  H. J. Moore,et al.  The Martian surface layer , 1992 .

[49]  A. Banin,et al.  Surface chemistry and mineralogy , 1992 .

[50]  B. Jakosky,et al.  Interpretation of planetary radar observations: the relationship between actual and inferred slope distributions , 1993 .

[51]  B. Butler.  3.5-cm radar investigation of Mars and Mercury : planetological implications , 1994 .

[52]  T. Parker,et al.  Scientific rationale for selecting northwest Isidis Planitia (14 deg - 17 deg N latitude, 278 deg - 281 deg longitude) as a potential Mars Pathfinder landing site , 1994 .

[53]  M. Golombek,et al.  Mars Pathfinder Landing Site Workshop , 1994 .

[54]  H. J. Moore,et al.  Atlas of volcanic landforms on Mars , 1994 .

[55]  Preliminary Cartographic Analysis of the Pathfinder Landing Site Using Viking Orbiter Images , 1995 .

[56]  Alexander S. Konopliv,et al.  The JPL Mars gravity field, Mars50c, based upon Viking and Mariner 9 Doppler tracking data , 1995 .

[57]  K. Edgett,et al.  Mars Pathfinder Landing Site Workshop 2: Characteristics of the Ares Vallis Region and Field Trips in the Channeled Scabland, Washington , 1995 .

[58]  R. Morris,et al.  Hematite, pyroxene, and phyllosilicates on Mars: Implications from oxidized impact melt rocks from Manicouagan Crater, Quebec, Canada , 1995 .

[59]  R. Haberle,et al.  Atmospheric effects on the mapping of Martian thermal inertia and thermally derived albedo , 1995 .

[60]  High-Resolution Topographic Map of the Ares Tiu Landing Site from Viking Orbiter Data , 1995 .

[61]  David E. Smith,et al.  The Shape of Mars and the Topographic Signature of the Hemispheric Dichotomy , 1996, Science.

[62]  J. Harmon.  A radar study of the Chryse region, Mars , 1997 .

[63]  V. Baker,et al.  Paleohydrology and flood geomorphology of Ares Vallis , 1997 .

[64]  Mars Pathfinder landing site assessment with Goldstone delay‐Doppler and CW radar experiments , 1997 .

[65]  K. Edgett,et al.  Catastrophic flood sediments in Chryse Basin, Mars, and Quincy Basin, Washington: Application of sandar facies model , 1997 .

[66]  M. Golombek,et al.  Size‐frequency distributions of rocks on Mars and Earth analog sites: Implications for future landed missions , 1997 .

[67]  M. Golombek.  The Mars Pathfinder Mission , 1997 .

[68]  K. Edgett,et al.  Rocks and aeolian features in the Mars Pathfinder landing site region: Viking infrared thermal mapper observations , 1997 .