Science

Satellite constellations threatening the night sky - astronomers

19:00 pm on 19 November 2022

An artist's illustration of the huge numbers of satellites and space debris in orbit (via the European Space Agency) Photo: CC BY NC 2.0

Astronomers say the very existence of their field of science could be threatened by the huge number of low-flying telecommunications satellite constellations now in the sky - launched by companies such as Space X in the US and OneWeb in Britain.

The satellites' glinting solar panels and radio bleeps obscure cosmic objects and give false data to ground-based astronomy teams.

There are an estimated 400,000 recent and planned Low Earth Orbit satellites (LEOs) that are orbiting, anywhere between 250-2000kms above the surface of the Earth.

'It's drinking in all that light' - listen to the full interview  with Michele Bannister here

University of Canterbury planetary astronomer Michele Bannister said the pace of industrialisation in-near Earth Orbit has grown rapidly over the past three years.   

She said in the past three years, the number of active satellites in space has gone from 3000 to 7000.   

"There's more than 50 going up every two weeks at the moment," she said.

The Vera C. Rubin Observatory in Chile will soon use the largest camera ever built to capture 1000 images of the sky every night for a decade.

Designed to have a very wide view, the observatory has a mirror that is 8 meters across which gathers light and focuses to a depth of three magnitudes, deeper than previously possible.

Bannister said it is this observation, among others that is under threat.

University of Canterbury planetary astronomer, Dr Michele Bannister. Photo: University of Canterbury

She said, "When a satellite goes across that field of view, it's drinking in all that light, and it also will drink in the reflected sunlight that's off the satellite, and so that will leave bright streaks on every image that Ruben makes."

This, she said, may lead to false readings.

Bannister also said satellites constellations manoeuvring may also increasingly get difficult.

"There is already some sophisticated avoidance that's having to take place through automatic software.

"But you can see the rate of avoidance manoeuvres that's being made by these satellites that's tracked by a number of scientists and engineers around the world and it is accelerating quite rapidly.  

"At some point someone's going to blink at the wrong time."

Bannister said one solution could be to make basic observations early before it's too late to do them at all.

She said this is not an ideal way to approach science but it's something she and her colleagues are increasingly resigned to.

She said there needs to be a strong degree of international cooperation to ensure regulation in space as well as the environmental impacts of having too many satellites in space.

However regulatory changes are happening, she said.

"The US regulator on this, it decided in 1986 when there were barely any satellites in orbit compared to what we have now, that satellites didn't need to be considered for their environmental effects and so that decision has reverberated down to the present.  

"So in many ways, we're having to deal with the outcome of a decision that was made then.

"But just under two weeks ago they started to perhaps reconsider their position on this and start to modify their approach."

Bannister said New Zealand can take on a leadership position in this space.

"New Zealand has, more than half of our land mass, has some of the darkest skies in the world, and this is something that the rest of the world is realising that we still have because they've chosen not to have it anymore."

She said New Zealand's draft space policy talks about interacting peacefully and sustainably in space and thinking about environmental concerns of space.  

Comet C/2014 UN271 (Bernardinelli-Bernstein), as seen in a composite image made with the Las Cumbres Observatory 1-meter telescope. The first two images show satellites which show up as light streaks. The camera shutter stays open, so anything moving fast across the field of view leaves a streak. Photo: LOOK/LCO