Artificial satellites usually consist of machines or devices that are launched into space and orbit around the Earth or any other body in space. Currently, thousands of satellites orbit our planet. Satellites allow access or a view of large areas of the Earth's surface at any given time. This means they can collect massive amounts of data quickly compared to alternative instruments on the Earth's surface. Satellites are also used to study celestial bodies in space. Some of the most complex satellites include the International Space Station and the Global Positioning System. Artificial satellites orbit at varying distances from the Earth depending on their function. Most satellites occupy regions of the atmosphere known as the thermosphere and exosphere. The outer space refers to the expanse found beyond the Earth’s atmosphere between celestial bodies. The United Nations maintains a register of objects found in outer space. Several probes orbit around other natural bodies such as the moon, Venus, and Mercury.
The thermosphere is found at distances of between 53 miles to 400 miles from the surface of the Earth. It has high temperatures reaching up to 2,730 degrees Fahrenheit. Satellites in this region, however, do not suffer from heat damage due to the low pressure experienced in the region. The low Earth orbit is found in the thermosphere and partly in the exosphere. The low Earth orbit includes any orbit that is below 1,243 miles. The main occupants of the layer are the low-orbiting satellites. The International Space Station orbits around the Earth in the low Earth orbit. Instruments used for research purposes are also found in this orbital range so that they are better able to monitor events on Earth. Satellites in low Earth orbits move around the planet very fast, and the orbits also degrade more quickly. That means they require thrusters to keep them in orbit.
The exosphere extends up to 6,200 miles above the surface of the Earth. Several definitions of the exosphere also include regions of space up to the point where solar winds knock away atoms. This region does not have a distinct upper boundary as molecules float freely in the layer. The mid and high Earth orbits are located in the exosphere. Satellites in this layer can remain in their orbits for a very long time. Some can last decades without the need for adjustment. Communication and weather satellites are found on higher orbital ranges as they require more expansive views and access to large areas of the Earth at any given time. The geosynchronous orbit is found at the higher levels of the high Earth orbit. There are different types of geosynchronous orbits. The geostationary orbit is located above the equator and keeps a satellite in a given point throughout the orbit. Satellites in geosynchronous orbits have orbital periods similar to those of the Earth.
In recent years experts have raised the alarm over increasingly crowded orbits. Since launching of the Sputnik Satellite into orbit by the Soviet Union, thousands of satellites have been put into orbit by various entities including communication companies and the military. Scientists point out that crowded skies increase the likelihood of crashes between satellites and other vessels. It is, however, essential to note that collisions are rare since satellites are placed into orbits that typically avoid other satellites. Orbits do sometimes change and lead to accidents. In 2009, communication satellites belonging to Russia and the United States accidentally collided making it the first recorded crash between artificial satellites.