The number of objects launched into space now totals 16,466, at least 11,742 of which remain in Earth orbit. How do we avoid “Kessler Syndrome”?
José Álvarez Díaz specialises in international news and development and has worked as a correspondent in China for more than a decade.
Cross-posted from Equal Times
Space debris impact on Space Shuttle window – NASA, 1983
Between the launch of the Soviet Sputnik-1, the world’s first artificial satellite, in 1957, and the end of 2019, humanity sent some 8,500 objects into space. Three and a half years ago, 5,100 of those objects remained in orbit.
Less than five years later, thanks to the entry of new players into the space race – most of them private companies – the number of objects launched into space now totals 16,466 (as catalogued by the United Nations Office for Outer Space Affairs, UNOOSA), at least 11,742 of which remain in the Earth’s orbit. Though they also include discarded phases of rockets and similar objects, the vast majority are artificial satellites, vital to many of the technologies that we take for granted: weather forecasting, natural disaster warning, scientific observation of the Earth and the universe, and above all navigation systems such as GPS and telecommunications services (radio, television, telephone and internet), which serve countless areas of the planet with no other type of coverage.
Between 1964 and 2012, about 100 objects were sent into space each year, most of which were satellites. By 2022, 2,476 new objects a year were being sent into space. This record-breaking figure is set to be surpassed again this year: 1,869 objects have already been launched into space as of early September.
Much of this exponential growth over the last decade originates from the private sector: companies such as SpaceX, Blue Origin, OneWeb and Virgin Galactic offer satellite technologies that are much simpler and more short-term than those that were common until recently. These new technologies are based on ‘constellations’ of mini-satellites launched en masse at very low orbits.
This significantly decreases launch costs and provides a wider and more stable telecommunications signal due to the redundancy of so many satellites in one network, all of which orbit much closer together than did previous generations of satellites. SpaceX’s (Elon Musk’s US-based company) Starlink constellations alone, which provide internet from space, currently comprise more than 5,000 small satellites, which almost entirely encircle the planet at an altitude of 500 kilometres. There are currently plans to increase their number to 42,000 units. The downside of this system, which operates at low Earth orbit (LEO), slightly higher than the orbit of the International Space Station (ISS, at 400 kilometres), is that many more devices are needed to cover the same area of the Earth that was previously covered by only a few satellites spread out at much higher altitudes (objects at geostationary orbit [GEO], located at 35,786 kilometres above sea level, fly over the same point on the Earth’s surface all of the time).
Thus far we have only been considering whole objects left in space, about 10,000 of which are satellites currently in orbit, a number expected to increase to 75,000 by 2030. The picture gets even more complicated when we start counting all space debris, which numbers in the hundreds of millions. According to estimates in the European Space Agency’s (ESA) latest Space Environment Report, in November 2016, i.e. before the private sector’s explosive entry into the space race, hundreds of millions of artificial fragments ranging from one millimetre to more than 10 centimetres were already orbiting the Earth.
At tens of thousands of kilometres per hour, any impact with one of these objects could incapacitate, if not immediately destroy, a satellite or spacecraft. Such a space accident would generate thousands upon thousands of new fragments. Over time, collisions between these fragments could cause a cascade that would eventually disable the orbital ranges that our civilisation most relies upon, a nightmare scenario known as Kessler syndrome.
A future without satellites
As Holger Krag, head of the space debris office at the ESA, explains to Equal Times, if we continue to send satellites into space at the current rate and let them fall out of control at the end of their lifecycle until they are destroyed by friction with the atmosphere, humanity could lose access to space for “decades, or even centuries, in some orbits”.
“Just to give you an idea: a typical space object at 400 km altitude disappears from the space within one year. At 600 km of altitude, the atmosphere is thinner, and there, that would stay for 25 years; at 800 km, the atmosphere is already very thin, so it would stay for about 200 years. At 1,000 km, the atmosphere is absent, so it would stay in space forever.” Thus, he points out, despite their current congestion, “the lower LEO orbits will never be really polluted for a long time because the atmosphere constantly takes the objects down again. But at 800 km or 1,000 km, it could take centuries until these orbits are usable again”.
There is similar concern on the other side of the Atlantic. According to John L. Crassidis, professor of mechanical and aerospace engineering at the University of Buffalo (USA) and an expert on space debris, a subject on which he collaborates with NASA and the US Air Force: “GEO is starting to get crowded, but the problem isn’t near the LEO problem.”
“It’s tough to say when GEO will be a catastrophic problem. I think that if we don’t do anything to mitigate the LEO problem, then Kessler Syndrome will be a reality for LEO in less than 50 years […] One thing is for sure: if we don’t start to think about fixing issues in GEO, then Kessler’s Syndrome will reach out there too. The consequences are obviously profound,” he adds.
According to Krag of the ESA: “Both [orbits] are actually quite populated, but the highest risk that we have today is in LEO. If you look at 1 cubic km of space, in LEO it’s actually 1,000 times more densely packed than in GEO. So, in GEO, the situation is not good at all, but here we don’t face the risk of a chain reaction, of an avalanche of collisions. In LEO we do.” As Krag goes on to explain: “In LEO, four collisions have already occurred between objects. Each collision leaves fragments behind, which can then trigger a cascading effect of other collisions.” This is compounded by the hundreds of times that other objects have broken up on their own in space, through sheer wear and tear. “The risk is really there. You were asking when we expect the situation to run over into an uncontrolled growth. Well, we believe we are already there.”
“This has already started. We should not imagine this like a cascading effect that happens in a few hours or days. It is something that will set in very slowly, without us really noticing, and we will only notice when it’s too late,” says Krag.
As he explains, we can currently already expect one collision every five years. By 2100, however, this figure could be one collision every year, and by 2200 about five collisions a year. “It doesn’t sound like a fast process, and it’s not fast, but the problem is that it is unstoppable, because the objects that are required for this [to happen] are already in space, and they can already start all that. It’s just a matter of time until they hit each other”.
Trying to avoid accidents
In fact, congestion is such that, navigating in LEO currently requires making about two collision avoidance manoeuvres a year (the ISS also regularly performs such manoeuvres), with the added cost of fuel, operating time, labour and data not being collected. “There is usually about one manoeuvre a month, for planned reasons, but now there are two extra a year to avoid collisions,” he says. In addition to this wear and tear on the ground, additional effort is required from observatories, which have specific programmes for monitoring and cataloguing space debris. This is true of the Optical Ground Station (OGS) telescope at the Teide Observatory on the island of Tenerife (Canary Islands, Spain), which dedicates at least a third of its time to such tasks.
“The telescopes operate every night that the weather permits, so we are talking about maybe 120 or 150 nights a year, at least 30 per cent of the total time,” estimates physicist Julio Castro Almazán, a member of the Sky Quality Team at the Instituto de Astrofísica de Canarias (IAC), when interviewed by Equal Times. Castro shares the concern of the astronomical community about this problem and the rapid growth of satellite constellations in LEO. “It is very worrying. China even destroyed a satellite in LEO (the Fengyun-1C, in 2007, which increased the total fragments in orbit by 25 per cent in a single day) just to show that they could do it.”
While UNOOSA has several non-legally binding instruments at its disposal, countries are ultimately unable to stop what other countries do in space.
While agencies like the ESA are attempting to contain the problem by requiring new objects in orbit to be programmed for clean and total destruction upon reentry into the atmosphere, and others like NASA in the US and JAXA in Japan are limiting their additional fragment generation as much as possible (in addition to working to destroy older objects already in orbit in a controlled manner against the atmosphere, as the ESA achieved for the first time in history this summer), their counterparts in countries like Russia, China and India are still far from such commitments. However, Beijing has already laid the foundations for a future ‘Chinese Starlink’ with the 2021 creation of state-owned GW (‘Guowang’ or ‘National Network’ of satellites).
“Mega-constellations have opened up a whole set of other issues,” says Crassidis. “I think they are doing good things for humankind, but putting thousands of satellites in orbit certainly is not going to help the debris problem. […] I believe that the ‘bad’ outweighs the ‘good’ of these mega-constellations”.
The damage is done, but it’s vital that it doesn’t get worse
“The US and other allies are doing their best to mitigate debris and follow the guidelines,” says Crassidis. “For example, every satellite that has thrusters must do a controlled burn into the atmosphere. In the past satellites had to return to Earth after 25 years, which was changed to five years last year. Other countries, such as Russia and China, are not following any guidelines. Russia and the US have the most debris.”
The ESA is going even further with its ‘zero debris’ policy for all launches after 2030, and is developing its own technology, with robotic arms, to remove fragments already in orbit.
The “ESA cannot prescribe the rules to others,” says Krag. “But at least we can step up and deliver everything that you need […] so that the world can follow its example, or at least, they would find it difficult to explain why they are not following it.”
When it comes to the problem of chain collisions, “the only thing we can do is to limit this effect. We cannot stop it, but we can stop it [enough to] bring it to a level where it just grows softly and not so aggressively. But if we continue this way, we will see an exponential growth that is very hard to handle. Then, generations 50 or 100 years from now will not be able to use this region of space the way we do […] or maybe they won’t be able to use it at all anymore. And of course there would then be drama because we are just starting to use space and we want to get the navigation signals [GPS, etc.], we want to get all the observation data, we want to get weather forecasts, we even want to get broadbands of the internet from space […].”
According to Krag, we should all become more aware of this problem: “The public needs to know. There is sometimes a misconception that space is not used by the public, that space is something used by a few scientists that has no benefit for us on the ground. I think we need to educate people that the opposite is true: everybody using a smartphone is dependent of the services coming from space. People should know this because it’s the public that elects the government, and it’s the governments which will have to create space laws.” Perhaps, as some argue, humanity needs a Greta Thunberg of space junk.
This article has been translated from Spanish by Brandon Johnson
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