A low Earth orbit (LEO) is, as the name suggests, an orbit that is relatively close to Earth's surface. It is normally at an altitude of less than 2000 km but could be as low as 160 km above Earth – which is low compared to other orbits, but still very far above Earth's surface. Satellites in LEO typically take between 90 minutes and 2 hours to complete one full orbit around the Earth. Low altitudes in combination with short orbital periods make LEO satellites ideally situated for remote sensing missions, including Earth observation and reconnaissance. Fifty-five percent of all operational satellites are in LEO.