'In 1976, within 3 months, 2 U.S. spacecraft by this name soft-landed on the surface of Mars'
Viking
UNMANNED SPACE EXPLORATION: In 1976, within 3 months, 2 U.S. spacecraft by this name soft-landed on the surface of Mars
In 1976, within 3 months, 2 U.S. spacecraft by this name soft-landed on the surface of Mars
In 1976, within 3 months, 2 U.S. spacecraft by this name soft-landed on the surface of Mars
UNMANNED SPACE EXPLORATION
Viking
UNMANNED SPACE EXPLORATION