On January 2, 1959, the USSR’s spherical spacecraft Luna 1 became the first Earth vehicle ever to reach escape velocity of 11.2 km/sec (6.96 mps) – the speed required to break free of Earth’s gravity to continue forward without propulsion or without falling back to Earth or into Earth orbit. Luna 1 reached the speed on top of a rocket that worked in three stages. Once escape speed was achieved, Luna 1 separated from that third stage and continued on toward the moon, gathering data on Earth’s radiation belt.
Two days later, Luna 1 passed within approximately 6000 km (3728 mi) of the moon, discovering the moon had no magnetic field. As it continued on toward the sun, the sturdy little craft was the first to directly observe the solar wind, a stream of electrically charged particles flowing from the sun.
B Bondar / Real World Content Advantage