Radar Studies of Planets
Time delay
- converted to distance via velocity of light
- implies altitude of planetary surface
- Give maps of surface topography
Penetrates clouds (i.e. Venus)
Penetrates few mm of soil
- determines surface composition and roughness
- rougher surfaces backscatter better than smooth
- a smooth billiard ball only reflects from 1 spot on surface
- ice signature from Moon and, especially, Mercury
Ground based
- Mostly Arecibo 1000 ft, with powerful radar transmitters
- Venus, Mercury, asteroids have been studied
- H2O ice polarization signature found near N pole of Mercury
- frozen record of early Solar System