The Sunday Telegraph

Satellite ‘constellat­ions’ could end stargazing, warns astronomer

- By Sarah Knapton SCIENCE EDITOR

ASTRONOMY from Earth may become impossible because of mega-constellat­ions of satellites such as the OneWeb system, experts have warned.

Dr Paul Daniels, the president of the Federation of Astronomic­al Societies and a vice-president of the Royal Astronomic­al Society, said the night sky could be ruined for profession­al and amateur stargazers alike.

The UK is investing £400million to acquire a significan­t share in OneWeb, which has requested to launch 48,000 satellites 7,456 miles above Earth to allow a global communicat­ions network, offering internet and possibly GPS to everyone on the planet.

SpaceX is hoping to launch more than 41,000 in its Starlink fleet, and Amazon wants to put 3,236 satellites into low earth orbit, while Facebook’s Athena project is proposing up to 100,000 small satellites.

Studies show just 12,000 satellites would “seriously compromise” widefield telescopes, such as the Vera C. Rubin Observator­y in Chile, due to begin operation in 2022. There are also concerns it will hamper amateur contributi­ons to astronomy and the general enjoyment of the night sky.

“The pristine natural sky is the birthright of all the people of the world and which has inspired young and old for generation­s,” said Dr Daniels.

He added that because of the time it takes for satellites to transit to their orbits, there could be 250 satellites or more visible to the naked eye at some points.

“In addition, 500 or so satellite reentries per month around the globe will leave bright re-entry trails across the sky,” he added.

SpaceX now has 540 satellites in low Earth orbit with plans to treble that number by next year.

But there have already been complaints the trains of satellites are highly visible, streaking across the night sky.

Dr Daniels calculates huge areas of the night sky would contain satellites if proposed projects go ahead.

SpaceX has experiment­ed with a dark coating on the Starlink-1130 satellite, which has been dubbed “DarkSat”.

However the coating only reduced reflected light by 55 per cent and made the satellite much hotter which may significan­tly reduce its lifespan.

Traditiona­lly, satellites have been launched into orbits 22,000 miles above Earth but it means they have to be large, because they are so far away and can only see around 40 per cent of the Earth’s surface. Satellites in low Earth orbit can be very small and are cheap to launch. Communicat­ions signals also move between them more quickly so they are useful for global internet, but large numbers are needed to give blanket coverage.

Dr Daniels also fears that near-Earth space could become unusable because the chance of hitting something will be too great a risk to launch through.

“It will lead to a rapid growth in space debris that could endanger the lives of astronauts, damage existing satellites and, in worst case, potentiall­y deny humanity access to space for any purpose for decades,” he explained.

The European Space Agency estimates there are around 5,000 satellites in orbit of which 1,950 are still working and the other 3,050 are now “dead”.

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