Moons of Mars on the sides of Saturn (later discovered to be its rings), used the anagram "smaismrmilmepoetaleumibunenugttauiras" for "Altissimum planetam tergeminum observavi" ("I have observed the most distant planet to have a triple form"), Johannes Kepler had misinterpreted it to mean "Salve umbistineum geminatum Martia proles" (Hello, furious twins, sons of Mars). Perhaps inspired by Kepler (and quoting Kepler's third law of planetary motion), Jonathan Swift's satire "Gulliver's Travels" (1726) refers to two moons in Part 3, Chapter 3 (the "Voyage to Laputa"), in which Laputa's astronomers are described as having discovered two satellites of Mars orbiting at distances of 3 and
Mars mainly phyllosilicates and other minerals known from Mars, point toward an origin of Phobos from material ejected by an impact on Mars that reaccreted in Martian orbit, similar to the prevailing theory for the origin of Earth's moon. Although the VNIR spectra of the moons of Mars resemble those of outer-belt asteroids, the thermal infrared spectra of Phobos are reported to be inconsistent with chondrites of any class. Mars may have moons smaller than in diameter, and a dust ring is predicted to exist between Phobos and Deimos. Dozens of crewless spacecraft, including orbiters, landers, and rovers, have been sent