Luna 20 (Ye-8-5 series) was the second of three successful Soviet lunar sample return missions. It was flown as part of the Luna program, also called Lunik 20, as a robotic competitor to the six successful Apollo lunar sample return missions. Luna 20 was placed in an intermediate Earth parking orbit and from this orbit was sent towards the Moon. It entered lunar orbit on February 18, 1972. On February 21, 1972, Luna 20 soft landed on the Moon in a mountainous area known as the Apollonius highlands near Mare Fecunditatis (Sea of Fertility), 120 km from where Luna 16 had landed. While on the lunar surface, the panoramic television system was operated. Lunar samples
were obtained by means of an extendable drilling apparatus. The ascent
stage of Luna 20 was launched from the lunar surface on 22 February 1972
carrying 55 grams of collected lunar samples in a sealed capsule. It
landed in the Soviet Union on 25 February 1972. The lunar samples were recovered the following day.
This was the eighth Soviet spacecraft launched to return lunar soil
to Earth. It was evidently sent to complete the mission that Luna 18
had failed to accomplish. After a 4.5-day flight to the Moon, which
included a single midcourse correction on 15 February, Luna 20 entered
orbit around the Moon on 18 February. Initial orbital parameters were
100 x 100 kilometers at 65° inclination.
Three days later, at 19:13 UT, the spacecraft fired its main engine for
267 seconds to begin descent to the lunar surface. A second firing
further reduced velocity before Luna 20 set down safely on the Moon at
19:19 UT on 21 February 1972 at coordinates 3°32' north latitude and
56°33' east longitude, only 1.8 kilometers from the crash site of Luna
18. After collecting a small sample of lunar soil, the spacecraft’s
ascent stage lifted off at 22:58 UT on 22 February and quickly
accelerated to 2.7 kilometers per second velocity—sufficient to return
to Earth. The small spherical capsule eventually parachuted down safely
on an island in the Karkingir River, 40 kilometers north of the town of Jezkazgan in Kazakhstan, at 19:19 UT on 25 February 1972.
The 55-gram soil sample differed from that collected by Luna 16 in
that the majority (50 to 60%) of the rock particles in the newer sample
were ancient lunar highlands anorthosite (which consists largely of feldspar) rather than the basalt of the earlier one (which contained about 1 to 2% of anorthosite). The American Apollo 16
mission returned similar highlands material two months later. Like the
Luna 16 soil, samples of the Luna 20 collection were shared with
American and French scientists.
In March 2010, NASA reported that the Lunar Reconnaissance Orbiter had spotted the Luna 20.