In short, the European Space Agency's [GOCE][1] (Gravity Field and Steady-State Ocean Circulation Explorer) satellite was orbited in extremely low altitude elliptical [Low Earth Orbit][2] (LEO) with perigee of 195 kilometres (121 mi) and apogee of 201 kilometres (125 mi). At that altitude, there is still some atmospheric pressure, albeit extremely tenuous, but given the satellite's velocity and surface area still enough to result in meaningful drag and decreasing its orbital velocity. ![enter image description here][3] <sup>Artist's depiction of the European Space Agency's Gravity Field and Steady-State Ocean Circulation Explorer satellite in orbit.</sup> GOCE is even an aerodynamically streamlined satellite to reduce that drag to minimum possible and require less of its propellants to constantly do orbital [reboost][4] to increase its velocity and with it altitude, but since it ran out of its propellants, its orbit will slowly decay due to atmospheric drag and it will end its life falling towards the lower and denser atmosphere where it will presumably completely burn up. This reboost is a standard procedure also for the International Space Station (ISS) that currently orbits at the altitude of 230 miles (370 km), and each new visiting spacecraft (such as today's Soyuz TMA-11M that was just launched from Baikonur Cosmodrome) lends it a hand with that after the spacecraft successfully docks with the station. Some values and a graph of atmospheric pressure at LEO altitudes and beyond are listed on the Wikipedia page on [International Standard Atmosphere][5]. [1]: https://en.wikipedia.org/wiki/Gravity_Field_and_Steady-State_Ocean_Circulation_Explorer [2]: https://en.wikipedia.org/wiki/Low_Earth_orbit [3]: https://i.sstatic.net/WLXue.jpg [4]: https://en.wikipedia.org/wiki/Reboost [5]: https://en.wikipedia.org/wiki/International_Standard_Atmosphere