The Growing Space Junk Threat To Sat Nav:

Have you any idea how many satellites are currently orbiting the world? You may think it’s at the most a couple of thousand. In fact, it’s considerably more than that. UNOOSA ( United Nations Office For Outer Space Affairs) has calculated that there are now more than 6,000 of them circulating above us, albeit only about half of them are “active. As Martin McCoustra, a Professor in Chemical Physics at the Heriot-Watt University in Edinburgh, has pointed out on theconversation.com, the environment up there is becoming extremely congested.

This is creating a problem for astronomers as the bright surfaces on satellites can apparently reflect rays from the sun and so impede observations of distant galaxies and planets. Of even more concern, notes McCoustra, is the increasing risk of collisions. How fast a satellite has to move in order to maintain its orbit depends on how high it is above the Earth. At an altitude of 124 miles (200 km) the required velocity is around 17,500 mph – so if two of them crash into each other, the combined speed could potentially be up to 34,000 mph.

It’s an issue on which NASA (America’s National Aeronautics And Space Administration) has focused more intensively since a Chinese rocket weighing 18 tons plummeted from the sky on May 11th 2020. The CNBC correspondent, Todd Wasserman, subsequently cited NASA statistics indicating that there are now “21,000 pieces of space junk larger than a softball orbiting the Earth and 500,000 pieces of debris the size of a marble or bigger”. Hence the 8,800 tons of objects that humans have left in space are becoming a danger and “near misses” – such as between Elon Musk’s SpaceX Satellite and one from the European Space Agency in September 2019 – are far more frequent.

To date, though, there’s been just one major collision, in 2009, between the American satellite Iridium 33 and Russia’s Cosmos 2251, destroying both of them over northern Siberia. Wasserman also reported that the experts anticipate the situation will get much worse and that by 2025 as many as 1,100 satellites could be launched every year, with the number orbiting the Earth quadrupling over the next decade. There are, consequently, now a few companies such as Astroscale in Tokyo, Japan, who provide a “satellite and debris clean-up service”. In October 2019, Northrop Grumnan, a global aerospace, defence and security corporation based in Virginia, USA, launched its first Mission Extension Vehicle spacecraft (MEV-1) “to prove it could intercept failing satellites, repair them and put them back in orbit”. It rendezvoused with Intelsat 901 on 25th February 2020 and by 2nd April 2020 had extended 901’s operational capacity for a further five years.

NASA emphasises that satellites, like every other machine, don’t last forever, so eventually have to be disposed of. They can either be blasted further into space or, if they are relatively small and close to Earth, slowed down so they then burn up in the atmosphere. However, according to the European Space Imaging organisation, this process is not so simple for larger satellites in “low earth orbit”(LEO). To avoid them plunging onto populated areas, they are brought down to a remote area of the Pacific Ocean known as “Point Nemo”, which is thought to already house 250 – 300 obsolete spacecraft. The remnants of the Chinese rocket were an exception, dropping instead into the Indian Ocean, west of the Maldives archipelago.

Available data indicates that the USA has an estimated 3639 satellites in orbit, followed by the Commonwealth of Independent States (CIS: former USSR countries), 1532, China (456), Japan (196), the UK (191), India (101), France (78), Germany (73), Canada (69), Italy (31), Spain (29). In Latin America: Argentina (35), Mexico (14), Chile & Venezuela (3 each), Colombia, Peru & Ecuador (2 each), Uruguay (1).

The BBC Future contributor, Richard Hollingham, has speculated on what would happen if the space technology on which we all these days depend suddenly stopped working due, for example, to a massive solar storm, a cyber attack or impact from debris. Among the many dramatic repercussions he highlights would be the loss of the Global Positioning System (GPS), which enables us “ to travel from A to B without getting hopelessly lost on the way”.

A survey by the automotive firm Leasing Options, quoted in the Scottish Daily Record, has shown that 97% of respondents would feel stressed and probably wouldn’t even attempt to drive to a new place if they had to use road signs and a paper map instead of their Sat Nav to get to their destination. Only 36% said they’d stop and ask for directions if they couldn’t find the correct route and 70% of 18-24 year-olds (unlike most over-65’s) don’t ever carry a traditional road map in their car.

This reliance on technology can cause problems. One in five motorists questioned by Europcar revealed they’d been directed into fields, rivers and dead-end roads by their Sat Nav, with a marginally higher percentage admitting they’d had an argument with their device.

Filed under: Society, Travel | Posted on June 4th, 2021 by Colin D Gordon

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