analysis of its internal architecture. These were based on observations made by the Lunar Penetrating Radar (LPR) on board the Yutu-2 rover. Potential uses and missions Because the far side of the Moon is shielded from radio transmissions from the Earth, it is considered a good location for placing radio telescopes for use by astronomers. Small, bowl-shaped craters provide a natural formation for a stationary telescope similar to Arecibo in Puerto Rico. For much larger-scale telescopes, the crater Daedalus is situated near the center of the far side, and the rim would help to block stray communications from orbiting satellites. Another potential candidate for a radio telescope is the Saha crater. Before deploying radio telescopes to the far side, several problems must be overcome. The fine lunar dust can contaminate equipment, vehicles, and space suits. The conducting materials used for the radio dishes must also be carefully shielded against the effects of solar flares. Finally, the area around the telescopes must be protected against contamination by other radio sources. The Lagrange point of the Earth–Moon system is located about above the far side, which has also been proposed as a location for a future radio telescope which would perform a Lissajous orbit about the Lagrangian point. One of the NASA missions to the Moon under study would send a sample-return lander to the South Pole–Aitken basin, the location of a major impact event that created a formation nearly across. The force of this impact has created a deep penetration into the lunar surface, and a sample returned from this site could be analyzed for information concerning the interior of the Moon. Because the near side is partly shielded from the solar wind by the Earth, the far side maria are expected to have the highest concentration of helium-3 on the surface of the Moon. This isotope is relatively rare on the Earth, but has good potential for use as a fuel in fusion reactors. Proponents of lunar settlement have cited the presence of this material as a reason for developing a Moon base. Named features Aitken (crater) Amici (crater) Anuchin (crater) Apollo (crater) Avogadro (crater) Bel'kovich (crater) Belopol'skiy (crater) Bergstrand (crater) Berkner (crater) Birkhoff (crater) Bjerknes (lunar crater) Bok (lunar crater) Campbell (lunar crater) Cantor (crater) Carnot (crater) Cassegrain (crater) Chandler (crater) Chappell (crater) Chernyshev (crater) Comrie (crater) Coulomb-Sarton Basin Crookes (crater) d'Alembert (crater) Daedalus (crater) Davisson (crater) Delporte (crater)