The final frontier
The data from the 18th Space Control Squadron of the US Air Force was clear. In a week’s time, two satellites travelling at speeds of up to 17,500mph had a one-in-a thousand chance of smashing into each other – ten times higher than the normal threshold for moving a spacecraft to avoid a potential crash. If a collision occurred, a vast field of space debris would be created, with every piece of twisted metal ready to cause yet another collision.
The European Space Agency (ESA), which owned one of the satellites, Aeolus, saw the data and got worried. It tried to contact SpaceX, billionaire Elon Musk’s company that owned the other satellite, Starlink 44. For four days, they heard nothing. SpaceX said a bug in their system meant they missed the increasingly urgent emails from ESA.
When SpaceX finally responded, it said it had no plans to move its satellite. So, on 2 September 2019, ESA sent commands to Aeolus that triggered a series of thruster burns just a few minutes apart, moving it out of the way half an orbit before the potential collision. Everyone breathed a sigh of relief. Yet even if the two satellites had collided, there would have been no legal repercussions for either party. Operators simply have to rely on goodwill and self-preservation – in the hope that one party will get out the way in time – because in space, there are almost no rules.
Such a scenario is no longer acceptable, argues Dr Jonathan Eastwood (MSci Physics 2000, PhD 2003), a Reader in Space Physics at Imperial. “There are actually very few rules and regulations about how things should work up there,” he says. “We’re now standing on the precipice of lots of companies wanting to launch thousands of satellites into space, and that throws into sharp relief how we look after the space environment.”
The recent rejuvenation of NASA’s moon and Mars programmes are just one piece of an increasingly hectic schedule of activity. At the same time, Russia wants to build its own space station and China aims to have put its first astronauts on the moon by the end of the decade. Even the UK is getting on board, sending out a satellite from British soil for the first time from Spaceport Cornwall. Then there’s companies such as SpaceX, Amazon, OneWeb and Telesat, who are launching thousands of new satellites into low Earth orbit – the area 500 to 2,000km above the planet’s surface – to improve global internet access. It may not look like it when you’re stargazing on a clear night, but the area around planet Earth is getting busy. Space-based systems are beginning to affect almost every aspect of our economy, security and day-to-day life, from GPS systems and weather forecasts to mobile communications, high-speed internet and military uses.
In fact, right now, there are around 8,840 man-made satellites in orbit around our planet, of which about 6,300 are still functioning. And there are just under 32,000 bits of debris – from failed satellites, discarded rocket boosters and weapons tests – hurtling around Earth at up to 17,000mph that these functioning satellites have to dodge, while simultaneously making sure they also do not bash into each other.
That’s not all the man-made debris in space, just the bits big enough for the US Department of Defense to monitor. There are also around one million pieces of debris measuring between 1 to 10cm circling around Earth, and an estimated 130 million pieces measuring between 1mm to 1cm. This might not seem like a problem: space, is, after all, pretty big. But in 1978, former NASA scientist Donald Kessler published a seminal paper outlining what’s now known as the Kessler Syndrome. Collisions, he pointed out, produce orbiting fragments, each of which increase the probability of further collisions. Each collision takes place at speeds of around 15,700mph in low Earth orbit, so even small pieces can cause considerable damage. This cascade could create more debris in an Earth-orbiting belt than natural debris from meteorites, making it harder and harder for spacecraft and satellites to operate.
Space debris danger
How do you solve such an inherently global problem? Imperial experts think that the first step is to create a robust framework for how to think about safety in space that works in a UK context – and that other nations can take inspiration from.
“We are using space more and more,” says Eastwood. “It’s what’s now known as a critical national infrastructure, in the sense that it is part of what we need to make everyday life work. But space is a very, very unforgiving environment. You really have to understand the technical, scientific and engineering constraints of it all. So if you want to develop policy in the UK around space that is sensible, it has to be evidencebased. We have to approach this area in a way that’s ultimately going to be sustainable, and we have a relatively short window of opportunity to define it before we put even more stuff into space.”
Eastwood is the director of Space Lab, an Imperial Network of Excellence, which connects all the College’s space expertise together and will ensure that Imperial’s world-renowned work and research can be easily accessed by industry and government. Space Lab recently teamed up with the London Institute of Space Policy and Law, an independent institution that brings together lawyers and academics in the field of space law, to examine what a UK Space Safety Policy might look like and how Imperial can play its part in enabling evidence-based policies. The report identified five key areas of space safety: space debris; space weather; space traffic management; planetary defence; and the impact of space activities on the Earth’s environment. The two organisations produced a further report last year outlining the specific safety issues around the ‘mega constellations’ of internet-beaming satellites that companies such as SpaceX are creating. And with the help of Imperial Forum – the College’s policy engagement programme – they have communicated this work to MPs and a Parliamentary inquiry.
Lots of companies want to launch satellites, but there are few rules about how things should work
Out of the five areas outlined in the report, the issue of space debris is causing the most international attention, with all 193 countries at the UN declaring it a “concern of all nations”. And Eastwood points out that, with the sheer volume of traffic up there, satellite operators will soon no longer be able to manually move their spacecraft out of the way of debris and other objects. He cites machine learning and AI as the possible best solutions to enable spacecraft to autonomously track and avoid collisions, something Imperial has a solid pedigree in, and particularly now that Imperial-X, Imperial’s new digital teaching and research initiative, has a specific initiative focused on the sustainable use of space.
“We have people in physics, civil engineering, aeronautics, computing and the Centre for Environmental Policy working on these areas. With problems like this you need to ask: what should we do, and then what is sensible and economically feasible to do; and for that, you really need to have technical understanding.”
Eastwood also believes an international Space Traffic Management system will be required for mega-constellations of satellites and their services to coexist with other systems, both in space and on the ground. New laws also need to be created to determine what happens if a company running a constellation of satellites goes bankrupt, and who would take over to ensure their continued safe operation.
There is also a risk that satellites could be rendered useless by space weather, such as solar storms, that could transform them into space debris that is then impossible to move out the way of other objects. Imperial, however, is already making a significant impact in forecasting what space weather events are on the horizon, working with both the Met Office and ESA to build computer models that can give a better real time understanding of what the space environment is like.
“If you can give satellite operators earlier warning of what the conditions are likely to be, then they can operate their constellations in different ways to minimise the risk. So, for example, you might decide to put them in safe mode or not do a software patch during that time,” Eastwood says.
And it’s increasingly clear that what we do in space can have a powerful effect on what happens here on Earth, too. For example, there have been calls to make the satellite constellations of SpaceX and other companies darker to ensure they do not affect ecology on Earth, such as animals navigating by star patterns. The report warns that constellation satellites will soon be so plentiful and bright that they will hamper astronomers’ observations and could even stop them spotting dangerous asteroids. However, at the same time, satellites need to give off some form of emission so operators can keep track of where they are and ensure they do not collide with anything else.
Space Lab is aware that the UK making new policies or laws around space safety will make little overall difference if other nations also do not improve their regulations. However, it believes if the UK can show success in this area, it will inspire other countries. “Nobody really wants the space environment to become polluted, but the risk is that it happens through a tragedy of circumstances,” says Eastwood. “My feeling is that a lot of this then depends on being able to work with others to demonstrate how things can be done. If we can generate the political momentum and will to all recognise that this is something we all need to deal with, then there should be a path through this. That’s not to say it will be easy, but I think we owe it to everybody to try.”
Imperial is the magazine for the Imperial community. It delivers expert comment, insight and context from – and on – the College’s engineers, mathematicians, scientists, medics, coders and leaders, as well as stories about student life and alumni experiences.
This story was published originally in Imperial 53/Winter 2022-23.