More than 2,200 satellites have been launched into space since Russia’s Sputnik 1 became the first artificial satellite to orbit the planet. But potentially tens of thousands of satellites will soon invade the night skies thanks to ambitious projects like SpaceX’s Starlink constellation. The Starlink constellation, which promises to beam high-speed internet to every corner of the globe from space, will maintain a fleet of about 12,000 satellites.
There are already 420 Starlink satellites in orbit and the company has vowed to launch batches of 60 satellites every month until the constellation is operational.
And SpaceX is not the only company eyeing-up prime real estate in low-Earth orbit (LEO), with the likes of Amazon and Telesat in Canada planning satellites constellations of their own.
According to Martin McCoustra, chair in Chemical Physics at Heriot-Watt University, UK, the concern is twofold.
Firstly, astronomers are concerned about the impact these satellite constellations will have on night-time observations of the universe.
In an article for The Conversation, Professor McCoustra wrote: “Crowding in low Earth orbit has inevitable consequences for ground-based astronomers.
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“Bright surfaces on satellites can reflect rays from the Sun – giving rise to a burst of sunlight directed towards the surface of the Earth.
“Such intense bursts of light are much stronger than the weak light sources typically being observed by astronomers and will impede observations of distant objects in space.”
SpaceX has already addressed the concern and has pledged to take steps to mitigate the problem, by painting the satellites black, changing their angle in orbit and deploying visors to lower how much sunlight they reflect.
Professor McCoustra said: “With some three percent of its planned constellation launched, SpaceX is at least responding to the concerns raised by astronomers.
“Hopefully other agencies planning satellite constellation launches will also be upfront with their political plans to reduce this serious problem to astronomical observation.”
We boost the risk of catastrophic events associated with orbital debris
Martin McCoustra, Heriot-Watt University
In March this year, SpaceX boss Elon Musk, 48, was asked about the possibility of Starlink interfering with observations.
He said: “I am confident that we will not cause any in astronomical discoveries. Zero. That’s my prediction. We’ll take corrective action if it’s above zero.”
But there is a second threat posed by a crowded orbit – the danger of space junk and orbital debris.
For satellites and spacecraft to maintain a steady orbit of the planet, they have to hit speeds of more than 17,000mph.
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But this is also true of any part or satellite piece that has broken off and is now racing around the Earth.
Professor McCoustra said: “Collisions between such objects can therefore occur at combined speeds of potentially up to 34,000mph at 124 miles – if it is head on.
“The effects of such impacts can be serious for astronauts and space stations – as the dramatic opening scenes of the 2013 movie Gravity depict.”
Many satellites and spacecraft are designed to stop objects smaller than 0.4 inches (1cm) from crashing into them.
But larger pieces can punch through a spacecraft like a bullet, potentially compromising the safety of a mission.
In August 2018, for instance, astronauts on the International Space Station (ISS) plugged a hole in the orbital laboratory, most likely caused by a micrometeorite or space junk impact.
The hole, which was about 0.07 inches (2mm) wide, led to a small drop in pressure on the ISS.
Professor McCoustra said: “There is little doubt that, with the increasing use and commercialisation of space, we boost the risk of catastrophic events associated with orbital debris.
“Agencies, both state and commercial, must recognise this and support efforts to reduce the likelihood of such events by taking steps to remove existing debris and reduce the potential for further debris by removing redundant satellites and other space vehicles.”
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