Luna 18
Luna 18 — a Soviet sample-return mission meant to repeat Luna 16's success (launched 2 September 1971). A faulty attitude-control engine left it in the wrong lunar orbit and then unable to hold its orientation on the descent; its signal ended on 11 September, taken to be the moment it struck rugged ground at the edge of Mare Fecunditatis.
Key facts
Mission & specifications
Mission
- Operator
- Lavochkin (USSR)
- Launched
- September 2, 1971
- Status
- Lost
Mission
Luna 18 was meant to repeat Luna 16's success and bring back a second robotic sample of the Moon. Launched on 2 September 1971 on a Proton rocket, it made course corrections on 4 and 6 September and fired its engine to enter lunar orbit on 7 September — but the burn stopped 15 seconds early. An attempt to reach the planned landing orbit of 16.9 by 123.9 km failed because of a problem with one of its attitude-control engines, leaving it in an orbit of 93.4 by 180.3 km. After 54 orbits and 85 radio sessions, controllers sent it down on 11 September. The attitude-control engine failed again, the spacecraft could not hold its orientation, and its signal ceased at 07:47:16 UT — taken to be the moment of impact, although it may have been about 100 metres above the ground. It came down in rugged, mountainous terrain at the edge of Mare Fecunditatis, the Sea of Fertility, at about 3.57° N, 56.50° E. An image from Lunar Reconnaissance Orbiter shows a crater that may be its impact site, but that is unconfirmed. Five months later Luna 20 landed nearby and succeeded.
- 1971Luna 18 launches toward the Moon on a Proton rocketLaunch
A second attempt at a robotic sample return.
Its engine stops 15 seconds early, and an attitude-control fault spoils the correction.
Unable to hold its orientation, it strikes rugged ground at the edge of Mare Fecunditatis.
Images
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