Wikipedia (12 Mar 2013, 13:23)
The Luna 10 spacecraft was launched towards the Moon from an Earth orbiting platform on March 31, 1966. The spacecraft entered lunar orbit on April 3, 1966 and completed its first orbit 3 hours later (on April 4, Moscow time). After a midcourse correction on 1 April, Luna 10, the second of two hastily prepared Soviet Ye-6S probes (that is, the backup), successfully entered lunar orbit two days later at 18:44 UT. A 245-kilogram instrument compartment separated from the main bus, which was in a 350 x 1,000-kilometer orbit inclined at 71.9° to the lunar equator.
Luna 10 was battery powered and operated for 460 lunar orbits and 219 active data transmissions before radio signals were discontinued on May 30, 1966.