As late as the 1950s there was still credible scientific opinion that we might have Martians. Astronomers observed evidence of canals on the martian surface, suggesting presence of water, which in turn suggested presence of life. Slowly, with more powerful telescopes scanning the surface, that “evidence” began to be debunked, but there was no substitute for an up-close examination of the planet, which NASA got with the Odyssey space mission,

On this day, February 19, in 2002, the Odyssey spacecraft, in orbit around the red planet, trained its instruments on the surface and began the work of surveying. It has three main instruments: a thermal imaging system to determine the mineral composition of the martian ground; a radiation spectrometer; and a gamma ray spectrometer to test for chemicals on the surface, including hydrogen for the presence of water.

The Odyssey was also to act as a relay for the martian rovers that would land on the planet in 2004. With both the two rovers and the Odyssey continuing to provide scientific data about Mars to this day, astronomers have mapped out in detail a great portion of the planet’s surface and climate. So far, though, no martians have been discovered.