Early exploration , which revealed for the first time the far side of the Moon. Clearly visible is
Mare Moscoviense (top right) and a mare triplet of
Mare Crisium,
Mare Marginis and
Mare Smythii (left center). Until the late 1950s, little was known about the far side of the Moon. Librations periodically allowed limited glimpses of features near the lunar limb on the far side, but only up to 59% of the total surface of the Moon. These features were seen from a low angle, hindering useful observation (it proved difficult to distinguish a crater from a mountain range). The remaining 82% of the surface on the far side remained unknown, and its properties were subject to much speculation. An example of a far side feature that can be seen through libration is the
Mare Orientale, which is a prominent impact basin spanning almost , yet this was not even named as a feature until 1906, by
Julius Franz in
Der Mond. The true nature of the basin was discovered in the 1960s when rectified images were projected onto a globe. The basin was photographed in fine detail by
Lunar Orbiter 4 in 1967. Before space exploration began, astronomers expected that the far side would be similar to the side visible to Earth. On 7 October 1959, the
Soviet probe
Luna 3 took the first photographs of the lunar far side, eighteen of them resolvable, covering one-third of the surface invisible from the Earth. The images were analysed, and the first atlas of the far side of the Moon was published by the
USSR Academy of Sciences on 6 November 1960. It included a catalog of 500 distinguished features of the landscape. In 1961, the first globe (1:
scale) containing lunar features invisible from the Earth was released in the
USSR, based on images from Luna 3. On 20 July 1965, another Soviet probe,
Zond 3, transmitted 25 pictures of very good quality of the lunar far side, with much better resolution than those from Luna 3. In particular, they revealed chains of craters, hundreds of kilometers in length, based on data from Zond 3, with the catalog now including 4,000 newly discovered features of the lunar far side landscape. As many prominent landscape features of the far side were discovered by Soviet space probes, Soviet scientists selected names for them. This caused some controversy, though the Soviet Academy of Sciences selected many non-Soviet names, including
Jules Verne,
Marie Curie and
Thomas Edison. The
International Astronomical Union later accepted many of the names.
Further survey missions and
Mare Smythii visible, photographed by
Apollo 16 in 1972. It is much more
cratered than the
near side of the Moon. On 26 April 1962,
NASA's
Ranger 4 space probe became the first spacecraft to impact the far side of the Moon, although it failed to return any scientific data before impact. The first truly comprehensive and detailed mapping survey of the far side was undertaken by the American uncrewed
Lunar Orbiter program launched by NASA from 1966 to 1967. Most of the coverage of the far side was provided by the final probe in the series,
Lunar Orbiter 5. The far side was first seen directly by human eyes during the
Apollo 8 mission in December, 1968. Astronaut
William Anders described the view: It has been seen by all 24 men who flew on
Apollo 8 and
Apollo 10 through
Apollo 17, and photographed by multiple lunar probes. Spacecraft passing behind the Moon were out of direct radio communication with the Earth, and had to wait until the orbit allowed transmission. During the
Apollo missions, the main engine of the Service Module was fired when the vessel was behind the Moon, producing some tense moments in
Mission Control before the craft reappeared. Geologist-astronaut
Harrison Schmitt, who became the last to step onto the Moon, had aggressively lobbied for Apollo 17's landing site to be on the far side of the Moon, targeting the lava-filled crater
Tsiolkovskiy. Schmitt's ambitious proposal included a special communications satellite based on the existing
TIROS satellites to be launched into a
Farquhar–Lissajous halo orbit around the
L2 point so as to maintain line-of-sight contact with the astronauts during their powered descent and lunar surface operations. NASA administrators rejected these plans on the grounds of added risk and lack of funding. The idea of utilizing the Earth–Moon for a
communications satellite covering the Moon's far side has been realized, as
China National Space Administration launched the
Queqiao relay satellite in 2018. It has since been used for communications between the
Chang'e 4 lander and
Yutu-2 rover, which successfully landed in early 2019 on the lunar far side, and ground stations on the Earth. L2 is proposed to be "an ideal location" for a
propellant depot as part of the proposed depot-based space transportation architecture. The lunar far side was most recently seen and photographed by the three men and one woman aboard the
Artemis II lunar flyby in 2026.
Soft landing The
China National Space Administration (CNSA)'s
Chang'e 4 achieved the first ever soft landing on the lunar far side on 3 January 2019 and deployed the
Yutu-2 lunar rover onto the lunar surface. The craft included a lander equipped with a low-frequency radio
spectrograph and geological research tools. The far side of the Moon provides a good environment for
radio astronomy as interferences from the Earth are blocked by the Moon. In February 2020, Chinese astronomers reported, for the first time, a high-resolution image of a
lunar ejecta sequence, as well as direct analysis of its internal architecture. These were based on observations made by the
Lunar Penetrating Radar (LPR) on board the
Yutu-2 rover. CNSA launched
Chang'e 6 on 3 May 2024, which conducted the first lunar sample return from
Apollo Basin on the far side of the Moon. It was CNSA's second lunar sample return mission, the first achieved by
Chang'e 5 from the lunar near side four years earlier. It also carried a mini "Jinchan" rover to conduct
infrared spectroscopy of lunar surface and imaged the Chang'e 6's lander on the lunar surface. The lander-ascender-rover combination was separated with the orbiter and returner before landing on 1 June 2024 at 22:23 UTC. It landed on the Moon's surface on 1 June 2024. The ascender was launched back to lunar orbit on 3 June 2024 at 23:38 UTC, carrying samples collected by the lander, and later completed another robotic rendezvous and docking in lunar orbit. The sample container was then transferred to the returner, which landed in
Inner Mongolia on 25 June 2024, completing China's far side sample return mission. The
Lunar Surface Electromagnetics Experiment (LuSEE-Night) lander, a mission to soft land as early as 2026 a robotic observatory on the far side designed to measure electromagnetic waves from the early history of the
universe is being developed by
NASA and the United States
Department of Energy. ==Potential uses and missions==