Last week SpaceX launched 60 Starlink telecommunication satellites – the first major launch of its ambitious fleet of up to 12,000 satellites, with the goal to eventually create ultra-fast internet services around the world.
The launch of the 227 kg (500 pound) satellites went off without a hitch, but a spectacular video of the ‘train’ of satellites above the Netherlands – taken by archaeologist and amateur astronomer Marco Langbroek – has sparked a discussion about the potential problems this Starlink fleet could cause in the night sky.
The video below is not what the Starlink satellites will look like when they have been fully deployed, as this video was taken less than 24 hours after launch.
According to Space.com, the satellites are not quite bright enough to be visible to the naked eye, and once they further disperse, they should get slightly dimmer again.
But naked eye is not everything when it comes to the needs of astronomers.
Existing satellites are already tricky for ground-based telescopes to deal with, explains Swinburne University astronomer Alan Duffy, who is also the lead scientist of the Royal Institution of Australia.
“Current satellites are a problem but astronomers have developed clever techniques for removing them,” Duffy told ScienceAlert.
“Optical telescopes like Pan-STARRS automatically mask the passing satellites from images, while with radio telescopes like ASKAP in Western Australia we scan the sky in the frequency gaps between otherwise blindingly bright satellite navigation signals like GPS.”
Therefore, the deployment of a network of 12,000 satellites would be unprecedented. The environment we live in is constantly full of radio waves – WiFi, phone towers, and wireless networks all emit lots of radio noise, but satellites are much worse for radio telescopes than anything ground based.
“A full constellation of Starlink satellites will likely mean the end of Earth-based microwave-radio telescopes able to scan the heavens for faint radio objects,” Duffy believes.
“The enormous benefits of global internet coverage will outweigh the cost to astronomers, but the loss of the radio sky is a cost to humanity as we lose our collective birthright to see the afterglow of the Big Bang or the glow of forming stars from Earth.”
Duffy thinks the Starlink fleet will make this radio frequency interference “inescapable”, and suggests we should “build a radio telescope on the far side of the Moon”, shielded from the radio noise here on the planet.
It appears that the issues with radio astronomy interference are yet to be fully addressed by SpaceX.
Last year, US National Radio Astronomy Observatory astronomer Harvey Liszt wrote to the United States Federal Communications Commission (FCC), expressing concerns about the project.
According to Liszt, coordination between several national observatories and SpaceX “trailed off inconclusively around the middle of 2017 after a tentative and rather preliminary treatment of radio astronomy’s concerns and the manner in which SpaceX planned to address them.”
One of the reasons we don’t have a comprehensive plan from SpaceX about the 12,000 satellites might be because these first 60 are still considered to be “test class satellites”. Additionally, in 2015, industry experts questioned whether projects such as Starlink can even be profitable.
But despite various concerns, SpaceX has confirmed on Twitter there are plans for up to six launches in 2019.
With that many satellites, it’s not just radio frequency pollution that might become a problem. There’s also space junk.
“SpaceX is proposing to add 12,000 new satellites in the Low Earth Orbit region, where most of the junk is. This is 40 percent more objects over a few years, in contrast to the 60 years it took to accumulate the current mass of space debris,” says Alice Gorman, a space archaeologist at Flinders University in Adelaide, Australia.
“We’re looking at a radically different debris environment.”
To be fair to SpaceX, they have a space debris mitigation plan which was lodged with the FCC in 2017 according to ArsTechnica; the plan outlined how the satellites would de-orbit once they near “the end of their useful lives (roughly five to seven years) at a rate far faster than is required under international standards.”
“[Satellites] will de-orbit by propulsively moving to a disposal orbit from which they will reenter the Earth’s atmosphere within approximately one year after completion of their mission.”
But that’s unlikely to help if a satellite is hit before it has a chance to get out of the way. And as the recent International Space Station scare highlighted, you only need a small hole to be a big problem. Even a small piece of debris can hurt a satellite.
“If this system fails, then SpaceX predicts it will take five years for a satellite to re-enter the atmosphere. That’s plenty of time for collisions to occur, especially when there is an increased density of material in orbit,” Gorman told ScienceAlert.
This sort of impact, with so many satellites around, could start a runaway collision cascade known as the Kessler Syndrome. The scenario, proposed by NASA scientist Donald Kessler in 1978, goes something like this: when the amount of objects in Earth’s orbit becomes high enough, one collision could create a cascade effect, creating more debris and increasing the likelihood of further collisions.
“There’s often a blind eye turned towards space debris issues – one estimate is that at least 40 percent of all missions have not followed UN and other guidelines for minimising the amount of new debris created,” says Gorman.
“SpaceX has done all the right things in relation to de-orbit, and avoiding collisions … How this works out with such a massive number of new satellites is something we’ll have to see.”