Swiss company ClearSpace will attempt to remove a launch vehicle’s payload adapter from orbit in 2025 in an ESA-funded mission. (Credit: ClearSpace)
Monday, September 19, 2022
More than half of the thousands of satellites in orbit are now non-functional, and the accumulation of floating space debris has been said to be a “mortal problem” for current and future space missions and human space travel. I’m here.
|One of the main issues in the design of space debris removal strategies is how to transfer energy between the debris (target) and chaser upon initial contact.|
According to the European Space Agency (ESA), an estimated 130 million objects smaller than 1 cm and 34,000 objects larger than 10 cm are moving in orbit at speeds of thousands of kilometers per hour. A report presented at this year’s European Congress on Space Debris suggests that the amount of space debris could increase 50-fold by 2100.
Many pieces of space junk are small but move very fast, and their impact has enough energy to incapacitate a satellite or severely damage a space station.
Both the Hubble Space Telescope and the Solar Maximum Mission (SMM) satellite were pierced by coin-sized holes by flying debris, and the mirrors of NASA’s James Webb Space Telescope were damaged by micrometeorites.
Most satellites were not designed with the end of their usefulness in mind. About 60% of her 6,000 satellites in orbit are currently out of order. These defunct satellites, along with smaller objects, pose a major problem for both existing and future satellites and space stations.
The mega-constellations of satellites currently being sent into space by companies such as SpaceX and Amazon are expected to transform access to the internet for all nations. But these private telecoms ventures will also bring 50,000 more satellites into an already dangerously populated orbit.
Scientists warn that the rapid development of megaconstellations is at risk of several “commons tragedies,” including terrestrial astronomy, Earth’s orbit, and the Earth’s upper atmosphere.
How to remove space debris
There is a growing concern called Kessler Syndrome, which creates an envelope of space debris that could impede human space travel, space exploration, and the use of satellites in parts of Earth’s orbit. It is sustained by collisions between space objects that produce more debris and can also damage global communications and navigation systems.
Therefore, the development of practical debris removal technology is an important and urgent task. Various strategies have been envisioned to solve the space debris problem, and some have recently been prioritized.
One of the main issues in the design of space debris removal strategies is how to transfer energy between the debris (target) and chaser upon initial contact. There are two priority approaches and his third approach in development.
|The parallels between the space debris problem and waste recycling cannot be overlooked. Clearly, we need to devise a circular economy strategy for space waste.|
Impact energy dissipation methods attempt to reduce the impact energy of fragments. In one approach, chaser satellites deploy harpoons to penetrate space debris. After a successful shot, the Chaser’s satellite, harpoon, and target are connected by an elastic tether, and the Chaser pulls the debris and re-enters the atmosphere, burning up together.
Neutral Energy Balance involves a magnetic capture scheme that uses magnetic coils to achieve a perfect energy balance between chaser and target. This is a soft docking method that precedes subsequent debris handling methods.
Fracture energy absorption aims to destroy small debris targets using high power lasers. The challenge, however, is developing a laser-battery combination that is powerful yet lightweight enough. A Chinese lab is developing a space-based laser system aboard the Chaser satellite that can target debris up to 20 centimeters in size.
The first Space Clearing project is scheduled for 2025 and will be led by ESA. This includes a consortium approach based on Swiss spin-off company ClearSpace.
The ClearSpace chaser rendezvous with the target and captures it using four robotic arms. The chaser and captured launcher then deorbit and burn up in the atmosphere.
High cost and more pollution
A key challenge is the substantial costs associated with these proposed solutions given the sheer scale of the space debris problem. Another important aspect is the potential impact of space-clearing efforts on the Earth’s atmosphere.
As the number of satellites and other objects grows, the idea that they will be incinerated in the atmosphere if removed from space is worrying climate scientists. Space debris is naturally drawn downwards and burns up in the lower atmosphere, but rising levels of carbon dioxide can reduce the density of the upper atmosphere, reducing its ability to pull debris back to Earth.
Combustion of an increasing number of satellites and other space debris (currently 80 tons per year) that fall naturally or by new removal methods also releases decomposition products into the atmosphere.
These certainly contribute to more carbon dioxide and other greenhouse gases. Decomposition of certain materials within the satellite can also release chlorofluorocarbon (CFC) gases that can damage the ozone layer.
The parallels between the space debris problem and waste recycling cannot be overlooked. Clearly, we need to devise a circular economy strategy for space waste.
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