More than half of the thousands of satellites in orbit no longer exist, and this accumulation of floating space debris has been described as a “fatal problem” for current and future space missions and human space travel.
An estimated 130 million objects smaller than 1 cm and 34,000 objects larger than 10 cm travel in orbit at thousands of kilometers per hour, according to the European Space Agency (ESA). A report presented at this year’s European Conference on Space Debris suggests that the amount of space junk could increase fifty-fold by the year 2100.
While many fragments of space junk are small, they travel so fast that their impact contains enough energy to disable a satellite or cause significant damage to space stations.
Both the Hubble Telescope and the Solar Maximum Mission (SMM) satellites have coin-sized holes pierced by flying debris and a mirror on NASA’s James Webb Space Telescope damaged by micrometeorites.
Most satellites are not designed with their utility end in mind. About 60% of the 6,000 satellites in orbit are now out of service. Besides small objects, these defunct satellites pose a major problem for both current and future satellites and space stations.
SpaceX’s Starlink mission plans to put a constellation of thousands of satellites into orbit to improve internet services around the world. Paul Hennessy/NoorPhoto via Getty Images
The massive constellations of satellites currently being sent into space by companies like SpaceX and Amazon are expected to transform Internet access for all countries. But these special communications projects will also contribute an additional 50,000 satellites into already populated orbits.
Scientists have warned that the rapid development of massive constellations threatens with several “tragedies of the commons,” including terrestrial astronomy, Earth’s orbit and Earth’s upper atmosphere.
Read more: Soon, 1 in 15 light points in the sky will be a satellite
Methods for removing space debris
There is a growing concern, described as Kessler syndrome, that we might create an envelope of space debris that could prevent human space travel, space exploration, and the use of satellites in some parts of Earth’s orbit. This scenario, which continues due to collisions between space objects creating more debris, could also damage global communications and navigation systems.
This is why the development of practical debris removal technologies is important and urgent. So far, various strategies for solving the space debris problem have been envisaged and some of them have recently been prioritized.
So far, not a single orbiting object has been successfully recovered from space.
A major issue in designing space debris removal strategies is how energy is transferred between the debris (target) and the pursuer during first contact. Two approaches are prioritized and a third is under development:
- Impact energy dissipation methods seek to reduce the impact energy of debris. In one approach, the stalker’s satellite deploys a bayonet to pierce space debris. After a successful shot, the stalker’s satellite, harpoon and target will become attached to an elastic rope and the stalker will pull debris to re-enter the atmosphere and burn together.
- Neutral Energy Balance includes a magnetic capture method that uses magnetic coils to achieve an optimal energy balance between the pursuer and the target. This is an easy mooring method and is an initial step for some later methods of getting rid of debris.
- Destructive energy absorption is intended to destroy small debris targets with a high-powered laser. But the challenge is to develop a combination of laser and battery that is powerful and lightweight enough. A laboratory in China is developing a space laser system to be installed on a hunting satellite capable of targeting debris up to 20 centimeters in size. NASA Orion’s project uses ground-based lasers to destroy small debris.
Read more: Piece of Chinese satellite nearly hit the International Space Station. They dodged it – but the junk space problem is getting worse
The ClearSpace Chaser is designed to use robotic weapons to capture space debris. ESA, CC BY-ND
The first space removal project is scheduled to take place in 2025 and will be led by the European Space Agency. It involves a consortium approach based on a Swiss subsidiary, ClearSpace.
The ClearSpace stalker will meet and capture the target using four robotic arms. The stalker and the captured bomber will then be ejected from orbit and incinerated in the atmosphere.
High cost and more pollution
The main challenge is the significant cost associated with these proposed solutions, given the enormous scale of the space debris problem. Another important aspect is the potential impact of space evacuation efforts on our planet’s atmosphere.
The idea that an increasing number of satellites and other objects will be burned up in the atmosphere when removed from space worries climate scientists. Space debris is naturally drawn downward and burns up in the lower atmosphere, but increased levels of carbon dioxide reduce the density of the upper atmosphere, potentially reducing its ability to draw debris toward Earth.
The burning of more and more satellites and other space debris (80 tons per year at present) falling either naturally or by new removal methods will release decay products into the atmosphere.
These will certainly contribute to an increase in carbon dioxide and other greenhouse gases. It is also possible that the decomposition of some materials in the satellites releases chlorofluorocarbons (CFCs), which could damage the ozone shield.
No one can miss the parallels between the problem of space waste and waste recycling. Clearly, we need to develop a circular economy strategy for our space waste.
The legal responsibility for space debris nowadays lies with the country of origin. This appears to conflict with future international cooperative programs to remove space junk.
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