Gulliver's Travels or satellites, which revolve about Mars". This may have influenced Voltaire, whose 1750 story "Micromégas" also refers to two moons of Mars. In 1877, Asaph Hall discovered the two real moons of Mars, Deimos and Phobos; in 1973 craters on Deimos were named Swift and Voltaire, and from 2006 numerous features on Phobos were named after elements from "Gulliver's Travels", including Laputa Regio, Lagado Planitia, and several craters. The term "Lilliputian" has entered many languages as an adjective meaning "small and delicate". There is even a brand of small cigar called Lilliput. There is a series of collectable model houses
Lithobraking launched, including penetrators on the two Phobos probe landers targeted for Mars' moon Phobos and ones for Mars itself on Mars 96 and Deep Space 2, but so far none have succeeded. The cancelled LUNAR-A probe would have carried penetrators to the Moon. Lithobraking as a method for de-orbiting a spacecraft has not been used due to the extremely high orbital velocities of most bodies (e.g. for the Moon it is over 7000 km/h). However, some small moons and asteroids have very low gravity and it could conceivably be used there (e.g. Phobos has an "escape velocity" of 40 km/h.)