Low earth orbit300 km to 2,000 km up is the closest safe orbit for satellites, home to famous names including the Hubble Space Telescope and the International Space Station (ISS).
Medium earth orbitAt 20,000 km up, satellites orbit the earth about once every 12 hours. Many navigation satellites, such as GPS and Glonass, sit in this orbit.
Geostationary orbitAt an altitude of 35,786 km, satellites orbit at the same speed the earth turns, once every 24 hours, hanging usefully and lucratively over a single location to transmit and receive information.
High earth orbitThe most distant earth orbiter is a Russian radio telescope, Spektr-R. It reaches the highest point in its elliptical orbit at 330,000 km, while at its lowest it is only 1,000 km from earth. .
Space begins 100 km up. Here, satellites are compressed into a column and arranged by altitude. Not all of them stay at one height—41 are in elliptical orbits that hang high above the planet before a quick trip through lower altitudes.
Launching satellites costs at least $4,653 per kilogram. The biggest is the ISS, at 420,000 kg after years of expansion. The heaviest unmanned satellites are , weighing up to 10,000 kg. Today, are the trend—cubesats weigh as little as 1 kg.
Two inflatable habitats launched by Bigelow Aerospace——orbit here to test technology. The company plans to build more space stations and a Moon lab in the future.
In the last decade, several next-generation satellite imagery businesses have launched to compete with industry leader and government image re-sellers. Most notable are now owned by Google, and which also has cameras on the ISS.
The largest commercial satellite constellation belongs to which has 70 satellites in orbit. operates the second-largest private constellation of 46 satellites, but the company is looking to convert some of its satellite communications spectrum into wi-fi.Most satellites primarily used for Government or Military purposes are done so by the US, China, and Russia. The US military manages 154, the Russian Ministry of Defense 80 and China’s People’s Liberation Army 52.
The twelve O3b Networks satellites provide broadband internet to the “other three billion” internet users in emerging markets.
Satellites have a fairly short life-span, often just five or ten years—43% of current satellites were launched in the last five years, 67% were launched since 2010, and just 3% of active sats are more than 20 years old. When they stop working, operators must burn them up in the atmosphere, send them to orbit the sun, or dump them into a storage orbit away from high-traffic altitudes.
Sirius XM’s constellation broadcasts radio to more than 51.6 million terrestrial listeners.
Consumer internet in space is a tricky business—only a few companies (, and ) provide the service directly using high-altitude satellites, and upstarts have a bad orbital omen in the , launched by now-bankrupt Lightsquared.Still, at least two companies—OneWeb and SpaceX—hope to launch hundreds of internet-beaming satellites into low-earth orbit in the years to come.
The rocket family responsible for the largest number of satellites orbiting earth right now is Ariane with 176, developed by what is now Airbus and launched in South America. Rounding out the top five are China’s Long March with 155; the Delta, now launched by the US firm ULA with 143; Russia’s Proton with 134; and Atlas, also a ULA product with 120. Upstart SpaceX has launched just 16 earth-orbiting satellites on its Falcon 9 rocket.