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Low Earth Orbit (LEO) is between 124-1240 miles above Earth, while Medium Earth Orbit (MEO) is from 1243 miles to geostationary orbit (GSO) at 22,236 miles. Satellites in GSO orbit once a day and are synchronized with Earth’s rotation. Proposed space hotels are in LEO, while solar-powered satellites are in GSO for continuous sunlight.
Low Earth Orbit is only slightly above Earth, by outer space standards, at 124 – 1240 miles (200 – 2000 km) in altitude. Below 124 miles, orbits degrade rapidly, causing surface impact, and above 1,240 miles or less, Earth’s radiation belts damage electronic equipment, necessitating special shielding. The region from 1,243 miles altitude to geostationary orbit (35,786 kilometers or 22,236 mi) is known as the Medium Earth Orbit. Low Earth Orbit, Medium Earth Orbit and Geostationary Orbit are known as LEO, MEO and GSO respectively. By comparison, the Moon orbits the Earth at an altitude of about 384.399 km (238.854 mi), placing GSO about 10% of the way to the Moon. Leo is only about 1% of the way to the Moon.
The International Space Station, probably the most familiar object currently in orbit aside from the Moon, hovers between 320 km and 347 km above the surface of the Earth. Objects in low Earth orbit frequently rotate around the Earth, for example the International Space Station makes about 17 orbits a day. As one climbs in altitude and maintains a constant speed, the distance required to make one full orbit increases geometrically and the number of orbits per day decreases.
In geosynchronous orbit, some 22,000 miles above the Earth, the satellites orbit only once a day and as such are synchronized with the rotational speed of the Earth, hence the name. A geosynchronous orbit means that a satellite returns to the same spot in the sky at the same time every day. The path traced by the satellite with respect to the earth’s surface is that of an inclined eight. This is the orbit used by many communications satellites, which are kept geosynchronous to simplify communications calculations. For example, the GPS navigation system is operated by four satellites in geosynchronous orbit, allowing three to be in the sky at any given time, the minimum needed for triangulation of a location on the ground.
Geostationary earth orbit (GEO) is a special case of geosynchronous orbit in which satellites remain in an absolutely fixed point relative to the earth’s surface at all times. This must be above the equator. This is the proposed location for a space elevator, as all parts of the elevator’s length would have to be synchronous to avoid twisting and warping.
Most of the proposed space hotels are placed in low Earth orbit. It’s comfortably close to Earth and even offers a better view than GSO. However, for solar-powered satellites, you should put them in GSO, because GSO gets almost continuous sunlight, while LEO gets sunlight only about half the time. The sun rises and sets anywhere between every 45 minutes and every few hours from someone’s vantage point in low Earth orbit.
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