Pioneer maps Venus' surface



On the basis of extensive radar data returned by NASA's Pioneer Venus spacecraft, scientists for the first time have mapped nearly the entire cloud-shrouded planet and identified huge continent-sized features—including mountains as high as Everest and deep rift valleys. Pioneer Venus has now mapped about 83% of the planet's surface and by month's end will have covered 93%. Prior to Pioneer, less than 1% of Venus' topography had been measured by ground-based radar. Venus' surface has never been seen because of the clouds which permanently cover the planet.