Düsseldorf It was last September when an almost gigantic collision occurred far overhead. The International Space Station (ISS) only narrowly avoided a piece of space debris. As a precaution, the astronauts on board had already moved to the rear, Russian part of the station in order to avoid being hit directly in the event of an impact. And Kristina Nikolaus realized again how close her statistics are to reality.
Kristina Nikolaus is co-founder of the Braunschweig start-up OKAPI: Orbits, a company that uses specially developed AI software to calculate the trajectories of debris in space and warns space companies of possible collisions. And she says: “Statistically speaking, we’ve basically only been waiting for five years for a huge collision between satellites and space debris or for an explosion to happen due to the residual energy contained.”
So far, thanks to evasive maneuvers such as that of the ISS in September, things have mostly gone well. But now that private and public space travel is only really picking up speed, it is only a matter of time. Because space travelers don’t clean up in space. And so it gets more and more full there.
Donald Kessler, astronomer at the US space agency NASA, warned of a syndrome that has been named after him since 1978: space travel will be riskier for future generations because more and more loose particles from previous space missions are wafting through space.
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His finding: Small particles from old space junk collide with each other by chance, creating a cascade of small explosions that eventually lead to a big bang in space – and have considerable potential for destruction. His recommendation: to get out of the usual practice as soon as possible, to simply leave large objects such as payload fairings, burnt-out upper stages and disused satellites in orbit to their own devices.
Well, the space industry didn’t listen to him. And so the number of parts continued to grow.
This means that there is such a hectic hustle and bustle in orbit that, statistically speaking, there is a collision every decade. Kristina Nikolaus “company is not the only one that sees a business in the chaos of space. Thanks to ever smarter control software, what seemed unimaginable in Kessler’s time is now conceivable: making space a safe place again not by avoiding it, but by removing rubbish. And around this idea, which is still being fueled by massive advances in artificial intelligence, new business models are constantly emerging.
Lasso-like cables or laser beams
In theory, everything is very simple: At the end of their lifespan, satellites and other spatial objects ideally reach a “cemetery orbit”. They are stored there and usually become so slow after a maximum of 25 years that they enter the earth’s atmosphere. There they then burn up.
However, this can only work if the satellites still have contact with the earth and enough fuel to get there in the first place. Inactive satellites remain in orbit and are prone to collisions. According to the European Space Agency (ESA), there are now around 129 million particles that have found their way into space in this way. 900,000 of them are larger than one centimeter, 34,000 larger than ten.
So these satellites and particles would have to be collected. But how? With long, lasso-like cables that are ejected and dock on to debris, some say. Shoot them with laser beams and burn them, say the others. No solution has yet prevailed, only the view: something has to happen.
And that’s where start-ups like OAKPI: Orbits, founded in 2018, come into play. The Lower Saxony people believe: You can avoid the problem before all the garbage ends up in orbit. The four founders of OAKPI: Orbits got to know each other through the university. Some of them researched space debris, some in the field of earth observation data. They developed software that can predict when a satellite is at risk from a collision.
It is fed from data sets from earth observation systems, radar systems and telescopes, which continuously collect and catalog location data from celestial bodies around the world. Artificial intelligence combines the collected data points and compares them with one another. Because if American telescopes register an object and it appears in Europe a week later, valuable conclusions can be drawn about the further behavior of the object over the next few decades.
The probability of a collision is calculated
OKAPI: Orbits’ customers are mainly commercial organizations that do not have the capacities of the much larger international space agencies. They usually have smaller satellite constellations – between five and 30 satellites – and invest in warning software to keep their objects in orbit for as long as possible. The probability of a collision is calculated for your satellites and an evaluation is then carried out to determine whether a diversion maneuver is statistically sensible.
“A small impact on a solar panel might still be manageable, but a head-on collision with a larger object in the center of the satellite would definitely be a total loss,” explains Kristina Nikolaus. The start-up has automated calculations that were originally carried out manually and by hand and made them directly applicable to customers. Only one person looks at the collision warnings issued and, if necessary, steers the satellite around – depending on the mission goal.
If a satellite is supposed to take a photo at a certain point in time over a fixed point on the earth, the maneuver strategy is adapted to this as cost-effectively as possible. On the one hand, a collision could be fatal, on the other hand, the satellites should only be deflected if the probability of a collision is really high. Every maneuver is expensive and shortens the lifespan of the satellite, because reparking uses a lot of fuel – and there are still no petrol stations in orbit.
Tidying up with the AI arm
While OKAPI: Orbits wants to avoid as much garbage as possible in space, the Swiss start-up ClearSpace has come up with a different approach: Its technology really removes old junk from space.
Visually like a giant octopus, a cleaning room probe is provided with long gripping arms that enclose the debris. “As soon as the object is secured, the spacecraft will put it on a reentry path into the earth’s atmosphere. There it burns up like a shooting star, ”explains start-up co-founder and CEO Luc Piguet.
The European Space Agency (ESA) is convinced and is planning the first clean-up with this technology in space from 2025. It was not until December 2020 that ClearSpace signed a contract with Esa worth 86 million euros.
The mission is complex and dangerous, because the ClearSpace space probe is not immune to a collision either. And the process is one thing above all: slow. Because at least at the beginning she can only collect one object on each excursion.
On the first ClearSpace-1 mission, it will recover part of a Vega rocket that has been spinning through space since 2013. Weight: 120 kilograms, about as much as a small satellite and easy to handle thanks to the cone shape. On the mission, the researchers first gain experience before they later pick up complicated parts or even several objects on follow-up missions.
The goal is neutral conditions for space travel, says Piguet. In the future, he wants to firmly anchor a rule: Everything that can go into space must also be able to go out again.
No rules – so far
But it’s been a thing of the past with rules: once the owners have lost contact with their satellite, it not only drifts through orbit indefinitely – it is also unclear who is responsible for it. “It’s a tremendous area of the market.
Today, money is made with data. The constant exchange of data anywhere and at any time is primarily possible at the moment using satellites, ”says Sabine Klinkner, professor for satellite technology at the University of Stuttgart. “But there are no uniform rules as to how many satellites come into orbit, and then of course there are also no controls to determine whether and how satellites are disposed of again.”
The Committee for the Peaceful Uses of Outer Space, affiliated with the United Nations, published guidelines for the handling of discarded satellites and rocket parts in 2007. However, these are not binding. The European Code of Conduct for Space Debris Reduction only suggests that satellites should re-enter the earth’s atmosphere after 25 years at the latest.
There is a lack of uniform and binding rules that take the problem to the root and ensure that no additional space junk is created in the future. Missions such as ClearSpace-1 or technologies such as OKAPI: Orbits, however, are only combating the symptom, believes Klinkner: “Uniform rules would be needed around the world to ensure that satellites, for example, carry enough fuel to be disposed of in the end. But that no longer works for the satellites that are in space today. ”
So the start-ups have enough to do just to cope with the current situation. In any case, a solution has to be found so that Kessler syndrome does not occur at some point.
More: This text comes from the new ada magazine. If you want to understand tomorrow today, please stop by: join-ada.com.