The International Space Station almost hit by the remains of a Chinese satellite

Earlier this week, the International Space Station (ISS) was forced to maneuver to avoid a possible collision with space debris. With a crew of astronauts and cosmonauts on board, this required an urgent change of orbit on November 11.

During the station’s 23-year orbital life, there have been around 30 close encounters with orbital debris that require evasive action. Three of these near misses occurred in 2020. In May of this year there was a hit: a small piece of space debris blew a 5mm hole in the ISS robotic arm built in Canada.

This week’s incident involved a fragment of debris from the defunct Fengyun-1C weather satellite, destroyed in 2007 by a Chinese anti-satellite missile test. The satellite exploded into more than 3,500 pieces of debris, most of which are still in orbit. Many have now fallen into the orbital region of the ISS.

To avoid the collision, a Russian Progress supply spacecraft docked at the station fired its rockets for just over six minutes. This changed the speed of the ISS by 0.7 meters per second and raised its orbit, which was already over 400 km high, by approximately 1.2 km.

Space debris has become a major concern for all satellites orbiting the Earth, not just the football field-sized ISS. In addition to notable satellites like China’s smaller Tiangong space station and the Hubble space telescope, there are thousands of others.

NASA’s Hubble Space Telescope (credit: Wikimedia Commons)

As the largest inhabited space station, the ISS is the most vulnerable target. It orbits at 7.66 kilometers per second, fast enough to travel from Perth to Brisbane in less than eight minutes.

A collision at that speed with even a small piece of debris could cause serious damage. It is the relative speed of the satellite and debris that counts, so some collisions could be slower while others could be faster and cause even more damage.

As low Earth orbit becomes more and more populated, there are more and more to come across. There are almost 5,000 satellites in operation already, and many more are on the way.

SpaceX alone will soon have more than 2,000 Starlink Internet satellites in orbit, en route to an initial target of 12,000 and perhaps eventually 40,000.

If it was just the satellites in orbit, it might not be so bad. But according to the European Space Agency’s Office for Space Debris, there are an estimated 36,500 artificial objects in orbit larger than 10 cm in diameter, such as defunct satellites and rocket stages. There are also about a million between 1 cm and 10 cm, and 330 million measuring 1 mm to 1 cm.

Most of these elements are in low Earth orbit. Due to the high speeds involved, even a speck of paint can pierce an ISS window and an object the size of a marble could penetrate a pressurized module.

ISS modules are somewhat protected by multilayer shielding to reduce the likelihood of punctures and depressurization. But there is a risk that such an event could occur before the ISS reaches the end of its useful life towards the end of the decade.

Of course, no one has the technology to track down every piece of debris, and we also don’t have the ability to remove all of that junk. However, possible methods to remove larger pieces from orbit are being investigated.

Meanwhile, organizations around the world like the US Space Surveillance Network are tracking about 30,000 pieces larger than 10 cm.

Here in Australia, tracking space debris is an area of ​​increasing activity. Several organizations are involved, including the Australian Space Agency, Electro Optic Systems, the ANU Institute for Space, the Space Surveillance Radar System, the Industrial Sciences Group, and the Australian Institute for Machine Learning with funding from the SmartSat CRC. In addition, the German Aerospace Center (DLR) has a SMARTnet facility at the Mt Kent Observatory of the University of South Queensland dedicated to monitoring the geostationary orbit at an altitude of around 36,000 km, home to many communication satellites, including the used by Australia.

One way or another, we will eventually have to clean up our space neighborhood if we are to continue to benefit from the regions closest to the “final frontier.”



Reference-www.jpost.com

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