Luna 18
 | |
| Operator | Soviet Union |
|---|---|
| Major contractors | GSMZ Lavochkin |
| Mission type | Planetary Science Lunar Sample Return |
| Launch date | 2 September 1971 13:40:40 UTC |
| Carrier rocket | Proton-K/D |
| Launch site | Baikonur Cosmodrome |
| Mission duration | 9 days |
| Satellite of | Moon |
| Orbital insertion date | 7 September 1971 |
| Orbits | ~48 |
| COSPAR ID | 1971-073A |
| Mass | 5,750 kg (12,680 lb) |
| Orbital elements | |
| Semimajor axis | 6,477.8 km (4,025.1 mi) |
| Eccentricity | .001361 |
| Inclination | 35° |
| Apoapsis | 100 km (62 mi) |
| Periapsis | 100 km (62 mi) |
| Orbital period | 119 minutes |
| Moon landing | |
| Date | 11 September 1971 07:48 UTC |
| Coordinates | 3°34'N 56°30'E |
| Instruments | |
| Main instruments |
Stereo photographic imaging system Remote arm for sample collection Radiation detector Radio altimeter |
| References: NASA NSSDC Master Catalog | |
Luna 18 (Ye-8-5 series) was an unmanned space mission of the Luna program, also called Lunik 18.[citation needed]
Luna 18 was placed in an earth parking orbit after it was launched and was then sent towards the Moon. On September 7, 1971, it entered lunar orbit. The spacecraft completed 85 communications sessions and 54 lunar orbits before it was sent towards the lunar surface by use of braking rockets. It impacted the Moon on September 11, 1971, at 3 degrees 34 minutes N, 56 degrees 30 minutes E (selenographic coordinates) in a rugged mountainous terrain. Signals ceased at the moment of impact.
This mission was the seventh Soviet attempt to recover soil samples from the surface of the Moon and the first after the success of Luna 16. After two mid-course corrections on 4 September and 6 September 1971, Luna 18 entered a circular orbit around the Moon on 7 September at 100 kilometers altitude with an inclination of 35°. After several more orbital corrections, on 11 September, the vehicle began its descent to the lunar surface. Unfortunately, contact with the spacecraft was abruptly lost at 07:48 UT at the previously determined point of lunar landing. Impact coordinates were 3°34' north latitude and 56°30' east longitude, near the edge of the Mare Fecunditatis ("Sea of Fertility"). Officially, the Soviets announced that "the lunar landing in the complex mountainous conditions proved to be unfavorable." Later, in 1975, the Soviets published data from Luna 18's continuous-wave radio altimeter that determined the mean density of the lunar topsoil.
- Launch Date/Time: 1971-09-02 at 13:40:40 UTC
- On-orbit dry mass: 5600 kg
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