Have you ever looked up at night and seen a shining object moving quickly across the sky? It's too small and too fast to be an airplane, and not quite bright enough to be a meteor, but what is it? It's probably a satellite! When the sunlight catches them just right, we can see them glisten in the night sky. Right now, there are 1,957 active satellites and 3,030 inactive ones in the orbiting our home planet. What do we use satellites for and how do they survive in space?
Satellites impact more parts of our lives than you might think, so it's essential that they work properly in orbit. Most of the currently active satellites handle communication and earth observations. Others are used for technology, GPS navigation, space observation and earth science data.Satellites are tied to every part of our daily life. If you've ever used GPS navigation on your phone, you've taken advantage of one of the many satellites orbiting in the atmosphere high above us.
There are three stages in a satellite's life. First, there's the engineering and design phase, which starts on a computer with a team of engineers first creating the satellite, then building it from the ground up. Step two is the launch phase, during which the satellite experiences massive gravitational forces as it moves into orbit. Finally, there's the vacuum phase — the final stop in the satellite's life.Satellites are put through space simulations and various other tests to make sure they will survive the rigors and pressures of each phase.
A satellite is broken down into five basic components as well as a few optional ones. The exterior of the satellite is known as the housing, and it protects all of the interior components. The power source — which can be solar, nuclear, fuel-based or any of the above — the command and control systems, and the transponder are all contained within the housing. Finally, the antenna helps the satellite communicate with Earth.Depending on what their jobs are, satellites may also be equipped with cameras and sensors, but these are optional additions that aren't necessary on every satellite.
Before a satellite can head into orbit, it needs to undergo plenty of testing to ensure it will survive the rigors of outer space. The tricky part of this is that it's usually the final version that is undergoing the testing — the one that will eventually be a launched into outer space. Each satellite undergoes vibration testing as well as thermal and vacuum testing.Vibration testing determines whether or not the satellite will survive the launch. Getting the satellite into orbit puts the components through up to three times the force of gravity and pressure of up to 15 lbs per square inch. To counter some of these pressures, they are equipped with kevlar and aluminum alloys.Thermal and vacuum testing determine whether the materials the satellite is made of — both internal and external components — will survive the vacuum of space and the extreme hot and cold temperatures.
So, how do satellites stay in orbit? It's all about speed. The satellite needs to move fast enough to defeat the pull of gravity. How fast it needs to move depends on its altitude. The International Space Station, for example, is in a low earth orbit, only 250 miles above the surface of the earth, so it needs to move 17,500 miles per hour. Satellites in a geosynchronous orbit, on the other hand, are 22,000 miles above the surface of the Earth, and only need to travel at around 7,000 miles per hour to stay in orbit.
There are thousands of satellites — both active and inactive — in orbit around Earth at any given time, and there will be thousands more in the not too distant future as companies like SpaceX and others launch tens of thousands of small communications satellites. Now the next time you see one streaking across the sky, you'll know why it moves so fast — because that's the only thing keeping it in orbit high above us.
Accessibility: If you are vision-impaired or have some other impairment covered by the Americans with Disabilities Act or a similar law, and you wish to discuss potential accommodations related to using this website, please contact us at (800) 270-2516
