Luna 17 continued the spate of successes in Soviet lunar exploration begun by Luna 16 and Zond 8. Luna 17 carried Lunokhod 1, the first in a series of robot lunar roving vehicles whose conception had begun in the early 1960s, originally as part of the piloted lunar landing operations. This was the second attempt to land such a vehicle on the Moon after a failure in February 1969. The descent stage was equipped with two landing ramps for the "ascent stage," that is, the rover, to disembark onto the Moon's surface. The 756-kilogram rover stood about 1.35 meters high and was 2.15 meters across. Each of its eight wheels could be controlled independently for two forward and two reverse speeds. Its top speed was about 100 meters per hour, with commands issued by a five-man team of "drivers" on Earth who had to deal with the 5- second delay. The set of scientific instruments was powered by solar cells (installed on the inside of the hinged top lid of the rover) and chemical batteries. After two midcourse corrections en route to the Moon, Luna 17 entered lunar orbit and then landed on the lunar surface at 03:46:50 UT on 17 November 1970 at 38_17' north latitude and 35_ west longitude, about 2,500 kilometers from the Luna 16 site in the Sea of Rains. The Lunokhod 1 rover rolled over the ramps and onto the lunar surface at 06:28 UT. The rover had an expected lifetime of three lunar days but operated for eleven. During its 322 Earth days of operation, the rover traveled 10.54 kilometers and returned more than 20,000 TV images and 206 high-resolution panoramas. In addition, Lunokhod 1 performed twenty-five soil analyses with its RIFMA x-ray fluorescence spectrometer and used its penetrometer at 500 different locations. Controllers finished the last communications session with Lunokhod 1 at 13:05 UT on 14 September 1971. Attempts to reestablish contact were finally discontinued on 4 October.
