From down here on the ground, space looks like a pristine void. But Earth’s orbit is actually crowded with satellites and a ton of stuff.
Well, it all depends on how you define a satellite! A satellite can be a body that orbits a larger body. If you take this as the definition of the satellite then the answer to your question is millions! These “millions” include actual spacecraft and any man-made debris that has been made during the past 30 years of space exploration.
We call this debris “space junk”. The debris orbits at the speed of some 7.5 kilometers a second. That is close to 17,000 miles/hour! So, imagine the damage even a tiny speck of debris could do to the space shuttle if it collided at such high speeds.
As of 2016, according to the index of objects launched into space, there were 4.256 satellites currently orbiting the planet. An increase of 4.39% compared to 2015. United Nations Office for Outer Space Affairs (UNOOSA) maintains that index.
In 2015, agencies launched 221 satellites, the second highest number in a single year. Although it is below the record of 240 launched in 2014.
The Union of Concerned Scientists (UCS) details which of those orbiting satellites are operational and it is not as many as you think! According to their June 2016 update, there were currently only 1 419 operational satellites – only about one-third of the number in orbit. This means there is quite a lot of useless metal hurtling around the planet! This is why there is a lot of interest from companies looking at how they capture and reclaim space debris, with methods such as space nets, slingshots or solar sails proposed.
What are all these satellites doing?
According to the UCS data the main purposes for the operational satellites are:
- Earth observation/science
- Technology Demonstration/Development
- Navigation & Global Position
- Space Science
Next time you stare at the night sky, remember that there are over two million kilograms of metal circling the Earth between you and the stars!