Space Debris
When we hear about environmental pollution problems, we typically hear about it as something in our rivers, forests, cities, and oceans. You may be tempted to look up at the blue sky and think that the realm of our impact is encapsulated in our earthly bubble. However, you may be surprised to learn about the millions of space debris orbiting our planet.
Since 1957, about 10,000 satellites have been launched into space with ~2,700 currently active satellites (1). For the first few decades, there was no plan to deal with satellites once they reached the end of their lifespan. This has effectively stranded many objects in orbits lasting hundreds to thousands of years, meaning without any intervention, this space debris will continue to orbit the earth.
“World’s Largest Garbage Dump”
There are millions of space junk flying in Low Earth Orbit (LEO). According to NASA there are now 6,000 Tons of Space debris in orbit (2), making LEO the “World’s Largest Garbage Dump”. Out of this, 900,000 of these objects are larger than 1cm, making them dangerous to other space craft (3).
Most debris are human-generated objects; such as space craft, rocket parts, small flecks of paint, satellites that are no longer working, and fragments caused by explosions of objects in orbit (2). This space junk can reach speeds of 18,000 miles/hour, and can cause hazards for active satellites, space-craft such as the international space stations, and even property on earth.
How to reduce space debris?
Today, one of the world’s most ambitious satellite projects is SpaceX’s Starlink. It is a program aiming to launch 40,000 satellites in LEO to beam broadband internet around the world. As of now, 2,300 of these satellites have already been launched, with many more to come in the next few years.
With the amount of satellites increasing substantially, what is being done to mitigate space debris?
Unlike on Earth, substantial progress has been made to curb the amount of debris in space. While there is no international law regarding space junk, guidelines were made to encourage operators to install satellites with debris mitigation systems.
Most satellites nowadays are equipped with a small reserve of fuel that will push the satellites into a different orbit at the end of their lives. Eventually these satellites will burn up in earth’s atmosphere. For example, each of Starlink’s satellites are scheduled to lower their orbits in 25 years, eventually self-destroying upon reaching the Earth’s atmosphere.
Research from the European Space Agency (ESA) shows that since 2000, between 60% -90% of new satellites launched into geostationary orbit are complying with these guidelines (1). Since many of these satellites occupy an orbit directly over the equator, there is strong incentive to mitigate any accidental collisions due to the relatively limited physical space.
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References:
1. https://www.bloomberg.com/news/articles/2020-10-19/space-garbage-solutions-could-help-fix-earth-s-plastic-problem-kggdc0e9
2. https://www.nasa.gov/centers/hq/library/find/bibliographies/space_debris
3. https://www.bbc.com/news/science-environment-54562501