Thematic maps and Martian landscapes · 102–103
Lava flows on Mars
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The upper image shows Martian lava flows in brighter shades, using observations made at a wavelength of 12.6 cm with the 305-metre Arecibo radio telescope. The telescope transmitted radio pulses towards Mars at a power of 440–820 kW and observed their reflections. Dark regions returned little signal: these are smooth surfaces from which the radar signal bounced away.
Brighter regions returned stronger signals, indicating rocks larger than 12 cm. These are probably lava flows covered with sharp lava blocks that are not conspicuous in elevation data or photographs. Radar can detect these centimetre-scale structures even from Earth. The lower image maps the region shown above.