Luna 21 (Lunokhod 2)

USSR

International Sat. n°:

USSR satellite n°:

Launch data:

Designation	06333 / 73001A
Launch date	08 Jan 1973
Launch site	B, LC-81/23
Launch vehicle	Proton-K/Blok-D
Satellite type	E-8 #3
Mission	Lunar Lander
Heliocentric orbit
Perihelion / Aphelion	90 x 110 km
Incl. to ecliptic	60.0 °
Period	min

Ye-8 lunar sample return spacecraft - detail of drill and reentry vehicle

Specifications:

Prime contractor	Lavochkin
Operator
Mass at launch	5567 kg
Dry mass	kg
Dimension
Basic shape
Solar array
Soft landing

Decay:

Moon landing date:	15 Jan 1973
Lifetime:

Description:

The basic Ye-8 was deigned to soft land on the Moon and deliver an automatic, self-propelled lunar vehicle, Lunokhod, for purposes of surveying sites for later manned landings and lunar bases. It was also intended that the spacecraft would provide a radio homing beacon for precision landings of later manned spacecraft. The design had its origins in Korolev’s L2 project of 1963. This evolved within OKB-1 to the globular Ye-8 of 1965 before further development of unmanned planetary spacecraft was passed to the Lavochkin bureau. There the design was refined and modified for a single launch by a Proton launch vehicle. By the time the spacecraft flew, America had won the manned moon race and mission objectives were to collect images of the lunar surface, examine ambient light levels to determine the feasibility of astronomical observations from the Moon, perform laser ranging experiments from Earth, observe solar X-rays, measure local magnetic fields, and study mechanical properties of the lunar surface material.
The lander had dual ramps by which the Lunokhod descended to the lunar surface. The lander and rover together weighed 1814 kg on the lunar surface.

Mission details:

The Proton / Block D launcher put the spacecraft into Earth parking orbit followed by translunar injection. On 12 January 1973, Luna 21 braked into a 90 x 100 km orbit about the Moon. On 13 and 14 January, the perilune was lowered to 16 km altitude. On 15 January after 40 orbits, the braking rocket was fired at 16 km altitude, and the craft went into free fall. At an altitude of 750 meters the main thrusters began firing, slowing the fall until a height of 22 meters was reached. At this point the main thrusters shut down and the secondary thrusters ignited, slowing the fall until the lander was 1.5 meters above the surface, where the engine was cut off. Landing occurred at 23:35 GMT in LeMonnier crater at 25.85 degrees N, 30.45 degrees E. The lander carried a bas relief of Lenin and the Soviet coat-of-arms. After landing, Lunokhod 2 took TV images of the surrounding area, then rolled down a ramp to the surface at 01:14 GMT on 16 January and took pictures of the Luna 21 lander and landing site. It stopped and charged batteries until 18 January, took more images of the lander and landing site, and then set out over the Moon. The rover would run during the lunar day, stopping occasionally to recharge its batteries via the solar panels. At night the rover would hibernate until the next sunrise, heated by the radioactive source. Lunokhod 2 operated for about 4 months, covered 37 km of terrain including hilly upland areas and rilles, and sent back 86 panoramic images and over 80,000 TV pictures. Many mechanical tests of the surface, laser ranging measurements, and other experiments were completed during this time. On June 4 it was announced that the program was completed, leading to speculation that the vehicle probably failed in mid-May or could not be revived after the lunar night of May-June. The Lunokhod was not left in a position such that the laser retroreflector could be used, indicating that the failure may have happened suddenly.

Ref.: #1, #8, #14 - update: 09.11.10

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