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| A Luna 23 launch cover, postmarked in Moscow with a hand cancel on October 28, 1974. |
Luna 23 was a Soviet unmanned lunar sample-return mission launched on October 28, 1974. It was part of the later, highly sophisticated phase of the Soviet Luna program, and was specifically designed to improve on the earlier Luna 16 and Luna 20 sample-return missions. Its primary objective was ambitious: land on the Moon, drill into the lunar surface, collect a deep core sample, and return the material to Earth. The modified Ye-8-5M spacecraft was designed to obtain material from considerably greater depth than the earlier Soviet sample-return missions—up to about 2–2.5 meters, compared with roughly 30 cm for Luna 16 and Luna 20.
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| A Luna 23 moon landing cover, postmarked in Moscow with a hand cancel on November 6, 1974. |
On November 6, 1974, the spacecraft descended to the lunar surface in Mare Crisium (Sea of Crises), at approximately 13° N, 62° E. The spacecraft successfully made a soft landing, but the landing itself was problematic. The terrain was unfavorable, and Luna 23 apparently suffered a hard or unstable touchdown that damaged its drilling equipment. The spacecraft ended up lying on its side rather than in its intended operating configuration. Because the drill was damaged, Luna 23 could not collect the planned lunar sample, and therefore its sample-return mission could not be completed.
The lander continued transmitting after touchdown and Soviet scientists were able to conduct a limited scientific program with the stationary spacecraft. The spacecraft remained in communication until November 9, 1974, about three days after landing.
