Luna 21The Soviet Union launches unmanned space probe Luna 21 toward the moon, carrying the Lunokhod 2 robotic rover. Like Lunokhod 1, this rover is solar-powered and can operate independently of its lander, though ground controllers push this vehicle further. Five months into its mission, Lunokhod is driven into a crater from which it is unable to escape; the mission is declared over a month later. This mission is not intended to return lunar soil samples to Earth.