Lunokhod programme in the context of "Orbiter"

Lunokhod 1 (Russian: Луноход-1, 'Moonwalker 1'), also known as Device 8EL No. 203 (Аппарат 8ЕЛ № 203, Apparat 8EL No. 203) was the first robotic rover on the Moon and the first to freely move across the surface of an astronomical object beyond the Earth. Sent by the Soviet Union it was part of the robotic rovers Lunokhod program. The Luna 17 spacecraft carried Lunokhod 1 to the Moon in 1970. Lunokhod 0 (No.201), the previous and first attempt to land a rover, launched in February 1969 but failed to reach Earth orbit.

Although only designed for a lifetime of three lunar days (approximately three Earth months), Lunokhod 1 operated on the lunar surface for eleven lunar days (321 Earth days) and traversed a total distance of 10.54 km.

Lunar Laser Ranging (LLR) is the practice of measuring the distance between the surfaces of the Earth and the Moon using laser ranging. The distance can be calculated from the round-trip time of laser light pulses travelling at the speed of light, which are reflected back to Earth by the Moon's surface or by one of several retroreflectors installed on the Moon. Three were placed by the United States' Apollo program (11, 14, and 15), two by the Soviet Lunokhod 1 and 2 missions, and one by India's Chandrayaan-3 mission.

Although it is possible to reflect light or radio waves directly from the Moon's surface (a process known as EME), a much more precise range measurement can be made using retroreflectors, since because of their small size, the temporal spread in the reflected signal is much smaller and because the return will be more evenly reflected with less diffusion.