Viking 1 was the first of two spacecraft, along with Viking 2, each consisting of an orbiter and a lander, sent to Mars as part of NASA's Viking program. The lander touched down on Mars on 20 July 1976, the first successful Mars lander in history. Viking 1 operated on Mars for 2307 days (over 61⁄4 years) or 2245 Martian solar days, the longest Mars surface mission until the record was broken by the Opportunity rover on 19 May 2010.