Viking 1, launched in 1975, made the first lasting Mars landing

Viking 1 launched from Cape Canaveral on August 20, 1975, and on July 20, 1976 its lander became the first spacecraft to work successfully on the surface of Mars. A Titan/Centaur rocket lifted the four-ton orbiter-and-lander pair off Complex 41 at 5:22 p.m. EDT, starting a half-billion-mile, 11-month journey.

The craft entered Mars orbit on June 19, 1976, and the lander set down on the plain of Chryse Planitia a month later. It was not the first machine to reach the Martian surface: the Soviet Mars 3 touched down in December 1971 but fell silent less than two minutes later. Viking 1’s opening frame, showing its own footpad on soil and rocks, was the first photograph ever taken from the surface of Mars.

Did Viking find life?

Not conclusively, and scientists still argue about it. Each lander dropped soil into a chamber, added nutrients tagged with radioactive carbon, and waited for microbes to eat them and release labelled gas. That is essentially what happened, and soil heated first to sterilise it stayed quiet, just as biology would predict. But nothing else the landers measured pointed to life, and NASA sums up the result as unexpected and enigmatic chemistry with no clear evidence of microorganisms.

Later missions found perchlorate, a non-living compound, in Martian soil that could have produced the signal, though studies question whether it explains everything.

How long did Viking 1 last, and what did it cost?

Far longer than planned, at a record price. Viking was meant to run for 90 days after landing. The orbiter instead completed 1,488 orbits before shutting down in August 1980, and the lander sent its final transmission on November 11, 1982, more than six years after touchdown.

Viking 1 and its twin, Viking 2, cost $1.06 billion, about $7.1 billion in 2020 dollars, and Viking remains NASA’s costliest robotic planetary science mission. More than half the money went into developing the two landers.