Research Article

Radar Soundings of the Subsurface of Mars

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Science  23 Dec 2005:
Vol. 310, Issue 5756, pp. 1925-1928
DOI: 10.1126/science.1122165


  • Fig. 1.

    (A) MARSIS data in radargram format for orbit 1855 as it crossed the margin of the NPLD. (B) Simulated MARSIS data if echoes are only from the surface (nadir and off-nadir clutter). (C) MOLA topography along the ground track (red line); elevation is relative to mean planetary radius. MARSIS data at 5 MHz show a split of the strong return into two as the ground track reaches the NPLD (higher terrain to the right). Maximum time delay to the second reflector is 21 μs, equivalent to 1.8-km depth in water ice.

  • Fig. 2.

    Location of the ring structure, northeast Chryse Planitia, in MOLA topographic data (positive east longitude). The inset at top left shows the location of the detailed map on a globe of Mars. Ground track positions are shown as vertical lines (1903 and 1892). Traces of ring structures that match in the two orbits are shown in red (1892) and white (1903).

  • Fig. 3.

    MARSIS data for orbits (A) 1892 (3-MHz band) and (B) 1903 (4-MHz band). Note the multiple arc-shaped reflectors near the center of each panel, and the planar reflector associated with the arcs in orbit 1903 (arrow). (C) Model of the nadir surface and off-nadir clutter for orbit 1903. No arc-like or planar features are predicted in the clutter model. (D) MOLA topography along the ground track of orbit 1903.

  • Fig. 4.

    Schematic showing the geometric relationships of a crater rim and floor in oblique view (left) and as seen in a sounder radargram (right). Note the appearance of multiple parabolic arcs and an associated planar reflector in the radargram. Compare with the radargram of orbit 1903 in Fig. 3.