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
International Space Station core of the cancelled Mir-2 space station, the hull of "Zvezda" was completed in February 1985, with major internal equipment installed by October 1986. The module was launched by a Proton-K rocket from Site 81/23 at Baikonur, on 12 July 2000. "Zvezda" is at the rear of the station according to its normal direction of travel and orientation, and its engines may be used to boost the station's orbit. Alternatively Russian and European spacecraft can dock to "Zvezda" aft port and use their engines to boost the station. Destiny, also known as the U.S. Lab, is the primary research facility