Space research days in the space station, but this achievement was quickly overshadowed since the crew died on reentry to Earth. Salyut 1 was intentionally deorbited six months into orbit since it prematurely ran out of fuel. Skylab was the first American space station. It was 4 times larger than Salut 1. Skylab was launched in May 19, 1973. It rotated through three crews of three during its operational time. Skylab’s experiments confirmed coronal holes and were able to photograph eight solar flares. From 1986 to 2001, Russian space station Mir served as a permanent microgravity research laboratory in which crews conducted
Low Earth orbit orbit is about 7.8 km/s, but reduces with increased orbital altitude. Calculated for circular orbit of 200 km it is 7.79 km/s and for 1500 km it is 7.12 km/s. The delta-v needed to achieve low Earth orbit starts around 9.4 km/s. Atmospheric and gravity drag associated with launch typically adds 1.3–1.8 km/s to the launch vehicle delta-v required to reach normal LEO orbital velocity of around . The pull of gravity in LEO is only slightly less than on the earth's surface. This is because the distance to LEO from the earth's surface is far less than the earth's