Space Debris

Space debris is a human-generated object that revolves in the earth's orbit that has no useful purpose such as tiny flicks of paint from a spacecraft, parts of a rocket, etc.? The speed of these objects is seven times faster than a bullet i.e. 18,000 miles per hour.?

The following are types of space debris that exist in the universe:

• Payload - it includes those satellites that are no longer in use and fragments produced by wear and tear and collisions.?
• Rockets - It includes remains of stages of rockets or spacecraft used to propel missions in orbit.?
• Mission-related objects - includes tools, screws, cables, cans, etc.?

Based on size it can be classified into three categories:?

• Below 1 cm - this kind of space debris is almost undetectable. There are more than 128 million such fragments or space debris in earth's orbit.?
• Between 1 and 10 cm—nearly 900,000 pieces of such debris exist on the planet. Its size varies from marble size to the radius of a tennis ball.?
• More than 10 cm - it includes lost tools to the defunct satellites.?

Consequences of space debris -?

• Huge effect on earth's environment: Almost 80 tons of space debris enters the earth's atmosphere every year, causing huge damage. Most of the debris burns out before even reaching the surface. It impacts Earth’s environment and atmosphere by releasing compositional chemicals into the atmosphere. These chemicals can deplete ozone, and the debris also poses a threat to future launches and space exploration. Some composite metals and polymers consume ozone when they push back through the atmosphere and burn up, experiencing chemical reactions that produce nitric oxide, which can deplete ozone.
• Increasing cost: Protecting satellites from space debris is expensive, beginning with design measures, the need for tracking, moving operational satellites out of harm’s way, and even replacing missions altogether.
• For satellites in geostationary orbit, the OECD reports that such costs amount to an estimated 5–10% of the total mission costs, which could be hundreds of millions of dollars. In low Earth orbits, the relative costs per mission could be even higher than 5–10%.
• Loss of unique applications and functionalities, for example, on the Internet.
• Increasing risk to astronauts' lives in space due to increasing rate of debris-spacecraft collisions.
• It causes light pollution, which can further decrease scientific discoveries in the future.

Space Debris Solutions

The main challenge is to produce less space waste. When it comes to debris already in orbit, many satellites and the International Space Station have Whipple Shields, an outer shell that protects the object's walls from a possible collision. Some strategies used to avoid this problem are:

• Orbit changes: many modern satellites are launched into elliptical orbits within the Earth's atmosphere, which causes them to break up eventually.
• Self-destruction: it means to program the satellite in such a way that it leaves its orbit at the end of its useful life and eliminates itself when it comes into contact with the atmosphere.
• Passivization is the process of removing any internal energy stored in a vehicle at the end of its useful life. The same can be done with debris.?
• Reuse: the rockets that return to Earth intact are used by SpaceX, the aerospace company owned by Elon Musk.
• Laser: consisting of stopping the fragments by vaporizing their surface with a powerful laser, which stops them and causes them to fall.