Viking 1
Viking 1 was the first of two spacecraft (along with "Viking 2") sent to Mars as part of NASA's Viking program. On July 20, 1976, it became the second spacecraft to soft-land on Mars, and the first soft lander to successfully perform its mission. (The first spacecraft to soft-land on Mars was the Soviet Union's Mars 3 on December 2, 1971, which stopped transmitting after 14.5 seconds.) "Viking 1" held the record for the longest Mars surface mission of days (over 6¼ years) or Martian solar days, until that record was broken by "Opportunity" on May 19, 2010.
Luna 1
Luna 1, also known as Mechta ( , "lit.": "Dream"), E-1 No.4 and "First Lunar Rover ", was the first spacecraft to reach the vicinity of the Earth's Moon, and the first spacecraft to be placed in heliocentric orbit. Intended as an impactor, "Luna 1" was launched as part of the Soviet Luna programme in 1959, however due to an incorrectly timed upper stage burn during its launch, it missed the Moon, in the process becoming the first spacecraft to leave geocentric orbit.