There have been three successful Mars lander missions, the Viking 1 and Viking 2 in 1976, and the Pathfinder in 1997.

CNN: Mars Pathfinder enlisted in search for lost Polar Lander

There were three biology experiments on the Viking lander 1 and Viking lander 2.

NPR: Revisiting the Viking Missions to Mars

In addition, the team has located all three of the other successful Mars landers, including Viking Lander 2 whose discovery was also announced on May 5th.

ECONOMIST: Has a missing Martian probe been spotted?

'The Viking' held his nerve in a thrilling match, coming back from 3-0 and 4-2 down in sets to win.

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