Mankind never thought about effects of its behaviors in long term. This is the main reason why air, water and soil pollution are serious problems today. Scientists are spending tons of hours to find new solutions to deal with pollution and we are being impressed by its negative effects everyday. On top of it, we have started to pollute the space, especially the Low Earth Orbit of our planet. I know that it sounds like a joke, but mankind has already encountered with the damage caused by space debris.
Every object in the Earth orbit that no longer in service is defined as space debris. Space debris is mostly consisted of retired or malfunctioning satellites, tiny pieces of paints, rocket parts or the junk of the space objects that are crashed with high velocity. Even the huge part of them is smaller than a piece of paper, the destruction that is created by them could be catastrophic.
“If most of the space debris are just like dots in the orbit of Earth, we don’t have to worry.” you may say. But unfortunately, that is not true. The danger caused by space junk is mainly resulted from the high speed that they can reach. Think about hundreds of these tiny pieces of spacecrafts moving with 18,000 miles per hour. According to European Space Agency, the amount of debris objects that are greater than 1 cm to 10 cm is estimated as 900,000. They also mention that there are 128 million objects bigger than 1 mm and smaller than 1 cm. You may still not believe these little pieces of junk can be dangerous for the giant spacecrafts in the orbit.
In 2007, debris bored a hole on the radiator panel of Endeavour space shuttle. The debris created a hole with 5.5 mm diameter while entering the panel. The diameter of exit hole was twice as large.
In 1993, a space mission has been conducted to carry out a maintenance service for Hubble Space Telescope. Solar panels of the telescope are changed and worn ones are sent back to the Earth. The team of ESA that was responsible from the solar panels of the telescope has discovered that the surface of the arrays were abraded, also hundreds of tiny craters were visible. Nine years after, solar panels have changed for second time and this time, it was a lot easier to see the damage that is caused by space debris.
In 2009, a ruined satellite, Kosmos 2251 and the operational Iridium 33 collided. This accident caused the malfunction of Iridium 33 and generated a huge discussion. By virtue of this crash, two satellites are destroyed.This was the first example of a noticeable spacecraft collusion with serious consequences.
The potential danger is not only limited with the risk created by the debris crashing with spacecrafts. Imagine two satellites that are no longer used but still in the orbit. If these bodies crash with each other, they can create hundreds of tiny pieces ready to damage active spacecrafts. As an example, the collision of Kosmus 2251 and Iridium 33 created thousands of pieces of space junk. Moreover, spacecrafts are making critical maneuvers to avoid a crash with an unexpected space junk and these maneuvers cost thousands of dollars. These reasons are showing to us that something must be done before it is too late.
Today, there are hundreds of satellites in the orbit whether they are still working or not, also new satellites continue on being launched. If we look at the projects like Starlink conducted by SpaceX which consists of the launch of 1,440 satellites, we can predict that space debris problem will be important more and more. So, what are the plans of space agencies or aerospace companies to deal with this issue?
In 1979, NASA has established Orbital Debris Program Office at Johnson Space Center. This program is responsible from modelling the debris currently in the orbit, determine the risk created by them, control the growth of the debris and guide agencies or companies about how to reduce the amount of junk or create less of them. United Nations restricts the life of a spacecraft that is no longer in use only with 25 years and the manufacturer is responsible with deorbiting. But as you can guess, these precautions are not enough to avoid new debris and get rid of the existing ones.
National space agencies and private companies are started to attach importance to develop missions for collecting debris and preventing the formation of them. Capturing the debris with the help of a trash collector satellite or integrating a deorbiting system to a satellite are two approaches to get over with space junk.
ESA is developing the first space debris removal satellite mission. The satellite, ClearSpace-1, is planned to launch in 2025. The satellite is designed to capture the debris with its arms and reenter to the atmosphere. At the end of this mission, the satellite and the debris going to be burned together in consequence of the reentry.
Another mission ,RemoveDEBRIS, was such an important step to better understand possible methods to capture debris. This demonstrative satellite, which is held by Surrey Space Centre at University of Surrey, was launched in April 2018. This mission was not planned to capture any existing space junk but to try the gear that is designed for getting rid of it. The satellite has demonstrated three different instruments: throwing a net to capture the junk, a harpoon to shoot the target and a dragsail to provide a self deorbiting system for any satellite. RemoveDEBRIS shown to us that a satellite can capture the junk by using several creative and improvable ways, also decrease its velocity by using the dragsail and reenter to the atmosphere by itself. These two missions are great examples to prove that space debris can be captured and any satellite can deorbit itself to prevent forming junk.
Space debris is an unminded problem in the shadow of bazillions of benefits of spacecraft missions. Thankfully, now it is considered as an important issue because of its undesired damage and cost potential. We have to take back the rubbish we put out of our house, the Earth. Let’s take the garbage in!
Sources:
https://www.esa.int/Safety_Security/Space_Debris/Space_debris_by_the_numbers
https://www.surrey.ac.uk/surrey-space-centre/missions/removedebris
