International Space Station program ocean was found to be possible only with Russia's assistance. At the time ISS was launched, the Russian Space Agency had experience from de-orbiting the Salyut 4, 5, 6, and 7 space stations, while NASA's first intentional controlled de-orbit of a satellite (the Compton Gamma Ray Observatory) would not occur for another two years. NASA currently has no spacecraft capable of de-orbiting the ISS at the time of decommissioning. Skylab, the only space station built and launched entirely by the US, decayed from orbit slowly over 5 years, and no attempt was made to de-orbit the station using a deorbital
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