“Ssince the dawn of the space age, we’ve had a throwaway culture – a bit like plastic in the ocean,” says Nick Shave, managing director of Astroscale UK, an in-orbit services company headquartered in Japan.
Getting a satellite into orbit around the Earth used to be a big deal. From the launch of the first, Sputnik, in 1957, as it became easier and cheaper to put satellites into space, the numbers increased. In 2022 there were approximately 6,000 and by 2030, one estimate suggests there will be nearly 60,000 satellites in orbit around our planet.
Look up on a clear night now and you may see a bright series of dots traverse the sky. It is part of SpaceX’s “mega-constellation” of satellites, Starlink, which provides greater access to broadband communications around the world.
But regulations on how people behave in space are piecemeal and the most important international law, the UN’s 1967 Outer Space Space treaty, is more than 50 years old.
There is now a large amount of debris, or space junk, in orbit. Nearly 37,000 objects larger than 10 cm are detected by space surveillance networks, according to the The European Space Agency’s (ESA) figures for September.
“That stuff is dangerous, don’t get me wrong,” said John Janka, chief global government affairs and regulatory officer at the communications company. Viasatwhich is based in Washington DC. “But there are also – according to Esa, more than 1 million pieces of debris between 1 cm and 10 cm that are deadly and untraceable. What does that mean? That means you can’t see it, you can’t avoid it, and today you can’t shield your satellite from it.”
But the debris concern is about more than damaging an individual satellite or spacecraft. Space operators are well aware of a danger known as the Kessler effect or syndrome, named after the NASA scientist Donald J Kessler, who in 1978 with Burton G Cour-Palais, published a theory that as the number of satellites increased, the probability of collisions would also increase. As collisions increase, the more debris is produced, and the greater the risk of more collisions. At a critical mass, one collision can trigger an unstoppable cascade of collisions, rendering an entire orbit useless.
A 2022 review paper by Viasat verf an almost apocalyptic picture: “If a tipping point is reached, all of humanity will watch helplessly as space debris proliferates uncontrollably. Without timely intervention, we risk bringing the space age to an inglorious end and trapping humanity under a layer of its own trash for centuries, or even millennia.
It continues: “Not only an abrupt end to space exploration, but also the loss of all the benefits of space technology – including navigation, weather forecasting, climate measurements and even satellite broadband (the intended purpose of the mega-constellations being deployed).”
As well as numbers, Janka points out, size is an issue. “We’re putting tens of thousands of satellites, and we’re putting bigger and bigger satellites into low Earth orbit – bigger in terms of cross-sectional area and mass – we’re finding that we might have an unexpected impact on things like collision risk.”
He compares it to a bigger sail on a boat that catches more wind. “The bigger the satellite, the more cross-sectional area, the more chance of being hit by debris.” And larger satellites create more debris when hit.
So what is the solution? Tracking and maneuvering satellites to avoid collisions is one way to manage risk. Elon Musk’s SpaceX manages its Starlink satellites this way, decommissioning those deemed “with an increased risk of becoming non-maneuverable“.
Many agree that maneuverability is important. Shave describes it as “critical in orbit”. However, this may not ultimately be a fail-safe solution due to the large number of satellites that will fill the skies in the coming years.
“Collision avoidance is a total misnomer,” says Hugh Lewis, professor of aeronautics at the University of Southampton, “because you can’t avoid a collision if you don’t know if a collision is actually going to happen or not.”
But a maneuver to avoid a future collision reduces the likelihood, he explains, so while the risk “never goes away”, it gets smaller. “Now multiply that [small risk] through 10,000 satellites,” he says.
Lewis, also a technical advisor to the Earth Space Sustainability Initiative (Essi), talking about “the law of really large numbers“. “You can have really rare events and if you give enough opportunity for that event to happen, then it generally happens, which is why we tend to see these big disasters that happen, even though they’re actually quite rare. The same is true with spacecraft [collisions].”
Ssatellites can be placed in different lanes depending on what their function is. For example, those placed in low Earth orbit (LEO) are relatively close to the Earth, 160-200 km above the surface, and are good for Earth observation. Other placed in high Earth orbit36,000 km above the earth, can be useful for weather monitoring. Satellites also use different frequencies or parts of the electromagnetic spectrum to communicate and – just as with radio frequencies on Earth – operators must apply for this limited resource through the UN’s International Telecommunication Union.
And as companies and nations compete for this limited resource – with early entrants able to commandeer orbits and bandwidths – it raises questions about how we fairly divide the air and share access to its benefits globally.
Ian Christensen, a senior director at the Secure World FoundationA US-based nonprofit, says that “constellation operators generally do well” in maneuvering their vessels out of harm’s way. For example, he says Starlink has a “higher threshold for collision avoidance than is typical” and its automatic collision avoidance system is “risk averse”.
“The concern comes from how different constellations will interact with each other … so as Chinese systems start to roll out, as Amazon starts to roll out Kuiper, as others come in, how do we ensure that they are coordinated, that operators exchange positional data, so that other operators know where they are?”
He says the concern is about how to build this coordination in the absence of a global system.
Coming together globally is “inevitable” according to some who argue that the space community needs to work together sooner rather than later and learn from the evolution of other technological game changers such as mobile networks and the Internet.
“We hope we can skip to the end. Let’s not go through the 10, 20, 30 years of doing it wrong,” says Michael Cheng, an advisory member of Essi and member of the Outernet Board.
These nonprofits support the space industry to develop “interoperable” systems. That is, different operators agree and use standardized hardware, software and network connections so that their satellites and space systems can “talk to each other”.
“We would like to see more efficient use of communication technologies and communication networks,” said Cheng, who is also chief product officer at the communications company. AlyriaA Google spin-off.
To help build resiliency into communications systems, the firm has a “network orchestration tool” or software called space time which monitors moving antennas and can find the best routes or connection options between moving satellites. It could also help operators trade network capacity with each other once licenses are in place, says Cheng.
He compares the current communication network in space to the early days of mobile networks on Earth where leaving the jurisdiction of one operator meant “exorbitant” roaming charges for the customer, while different mobile operators now have protocols and standards in place that make the system easier for everyone.
Sharing and standardizing systems in space will make things more efficient and therefore more sustainable – for example by reducing the amount of hardware that needs to be introduced.
“We’re betting on our ability to technologically outperform—or use technology to leverage our way out of whatever terrible things happen,” says Cheng, who argues that only by working together can we keep space sustainable. He cites one great success story for humanity – the banning of CFCs to help close the hole in the ozone layer. “Humanity has managed to work together and do a good thing there to make that hole smaller and smaller.”
However, Cheng also notes that the ozone layer may be under threat again – this time from disturbed satellites. A study published earlier this year in Geophysical Research Letters suggested that the spent satellites of mega-constellations could in the future produce more than 360 tons of aluminum oxide particles annually as they burn up in the Earth’s atmosphere. This could linger for decades and lead to “significant ozone depletion”.
most agrees the idea of interoperable systems makes sense, although Janka warns that this does not stop the “overconsumption problem”. “I think it’s critical to have a level of standardization in the right areas to enable space sustainability,” Shave says. He says the CEO of Astroscale, Nobu Okada, compares the situation in space now to more cars on the roads in the early 20th century. “You didn’t stop cars that stopped on the road,” he says. “You managed them better.”
His company won a £1.95 million contract with the UK Space Agency last month for the next phase of its Cleaning Outer Space Mission through Innovative Capture (Cosmic) spacecraft project, which aims to pluck inactive UK satellites from space using a robotic arm. If all goes according to plan, it hopes to launch Cosmic in 2027-28.
The mission’s goal of “active debris removal” may provide another way to keep orbits sustainable. “It’s imperative that we do this,” says Lewis. “We have to deal with the legacy of abandoned objects that have been abandoned over decades.”
With the threats to sustainability in space, some might argue that we should stop launching satellites altogether. But, argues Lewis, space services are now “part of our economy”. Rather, he asks, “How do we grow our use in a sustainable way?”
Janka’s firm wants to see the satellite industry model how different scenarios and solutions might work. He also calls for better regulation, adding that the industry has recognized this in the past year with an umbrella group, the Global Satellite Operators Associationwho agree on the importance of working with regulators. “We have to regulate because we are dealing with what is potentially a ‘tragedy of the commons‘. And unfortunately, with human behavior being what it is, we can’t operate with the assumption that everyone is going to do the right thing,” he warns.
Whether it’s interoperable systems, technological solutions or better rules for how we use space, the question of how we keep our activities in space sustainable is for everyone. “What happens in space affects a lot of what happens on the ground,” says Cheng.
“It’s not just about us. It’s about tomorrow … it’s about the next century,” says Lewis, “and leaving a legacy that allows other generations to use space the way we enjoy it.”
