Luna 23 was an unmanned space mission of the Luna program, also called Lunik 23. Luna 23 was a Moon lander mission which was intended to return a lunar sample to Earth. Launched to the Moon by a Proton SL-12/D-1-e booster, the spacecraft was damaged during landing in Mare Crisium (Sea of Crises). The sample collecting apparatus could not operate and no samples were returned. The lander continued transmissions for 3 days after landing. In 1976, Luna 24 landed several hundred meters away and successfully returned samples.

Luna 23 was the first modified lunar sample return spacecraft, designed to return a deep core sample of the Moon’s surface (hence the change in index from Ye-8-5 to Ye-8-5M). While Luna 16 and 20 had returned samples from a depth of 0.3 meters, the new spacecraft was designed to dig to 2.5 meters. After a midcourse correction on 31 October, Luna 23 entered orbit around the Moon on 2 November 1974. Parameters were 104 x 94 kilometers at 138° inclination. Following several more changes to the orbit, the spacecraft descended to the lunar surface on 6 November and landed in the southernmost portion of Mare Crisium. Landing coordinates were 13° north latitude and 62° east longitude. During landing in “unfavorable” terrain, the lander’s drilling device was evidently damaged, preventing fulfillment of the primary mission, the return of lunar soil to Earth. Scientists devised a makeshift plan to conduct a limited science exploration program with the stationary lander. Controllers maintained contact with the spacecraft until 9 November 1974.

• Launch Date/Time: 1974-10-28 at 14:30:32 UTC
• On-orbit dry mass: 5600 kg

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