In 1976 two identical Viking program landers each carried four types of biological experiments to the surface of Mars. The first successful Mars landers, Viking 1 and Viking 2, then carried out experiments to look for biosignatures of microbial life on Mars. The landers each used a robotic arm to pick up and place soil samples into sealed test containers on the craft.
The two landers carried out the same tests at two places on Mars' surface, Viking 1 near the equator and Viking 2 further north.[1]
- ^ Chambers P (1999). Life on Mars; The Complete Story. London: Blandford. ISBN 978-0-7137-2747-0.