This is the first photograph ever taken on the surface of the planet Mars. It was obtained by Viking 1 just minutes after the spacecraft landed successfully on July 20, 1976. The only organic chemicals identified when the Viking landers heated samples of martian soil were chlorine compounds interpreted at the time as likely contaminants from cleaning fluids. But those chemicals are exactly what the a study found when a little perchlorate — the surprise finding from Phoenix
— was added to desert soil from Chile containing organics and analyzed in the manner of the Viking tests.