Nasa's Mariner 8 falls into the ocean off Puerto Rico shortly after launch in 1971.
Later in the year, Mariner 9 becomes the first space craft to orbit Mars. It sends back close-up pictures of giant volcanoes, canyons and ancient riverbeds.
The Soviet Union has its first Mars successes with Mars 2 and Mars 3. They fly around the planet compiling data on the harsh Martian atmosphere.
The Mars 3 space craft releases a descent module which crash lands on the Martian surface, carrying the Soviet Union insignia.