This image of Mercury was the result of a radar experiment using the NASA JPL/DSN 70-m antenna in Goldstone, CA, as the transmitter, and the Very Large Array (VLA) as the receiver. Red areas are areas of high radar reflectivity, which can either be a result of surface and near-surface composition, or surface roughness. The north pole is the brightest region, an indication of the presence of significant amounts of water ice. A similar region has been detected at the south polar regions. The two other large reflective regions have never been photographed, so the cause of the high reflections remains a mystery.
Credit: Duane O. Muhleman (Caltech); NRAO/AUI/NSF
Technical Details Telescope: VLA Band: X Date: 1991-08-01