Discovery and exploration of the Solar System Earth to be orbited by an artificial satellite ("Luna 10"), followed by Mars in 1971 ("Mariner 9"), Venus in 1975 ("Venera 9"), Jupiter in 1995 ("Galileo"), the asteroid 433 Eros in 2000 ("NEAR Shoemaker"), Saturn in 2004 ("Cassini–Huygens"), and Mercury and Vesta in 2011 ("MESSENGER" and "Dawn" respectively). "Dawn" is orbiting the asteroid–dwarf planet Ceres as of 2015. The first probe to land on another Solar System body was the Soviet "Luna 2" probe, which impacted the Moon in 1959. Since then, increasingly distant planets have been reached, with probes landing on or impacting the surfaces of Venus in 1966
The Planet of Doubt The Planet of Doubt "The Planet of Doubt" is a science fiction short story by Stanley G. Weinbaum that was first published in the October 1935 issue of "Astounding Stories". It is Weinbaum's third story featuring Hamilton Hammond and Patricia Burlingame, a sequel to "Parasite Planet" and "The Lotus Eaters". Following his expedition to the night side of Venus, the Smithsonian Institution appoints Hamilton "Ham" Hammond to head an expedition to Uranus. In Weinbaum's version of the Solar System, all of the gas giants generate significant amounts of infrared radiation, enough to produce Earthlike environments on the inner moons of