What does Space Junk 1

Cleaning up in space

11/03/2020949 views3 likes

ESA's ClearSpace-1 mission will be the first garbage collection in space. Preparations for this are in full swing. The consortium selected in an international competition, led by the Swiss startup ClearSpace, is currently working on detailed construction plans for a “tow truck” that is scheduled to go into orbit in 2025. With its gripper arms, the ClearSpace-1 hunter is supposed to collect defective satellites and larger debris and remove them from earth orbit in order to reduce the risk of further collisions and the risk for active satellites.

"We have to take action if the earth's orbits are to remain usable," says Holger Krag, head of ESA's space security program. The headquarters of the Space Safety Program is located in the ESA satellite control center, the ESOC in Darmstadt. In autumn 2019, Krag's crew had to control an evasive maneuver for the ESA research satellite Aeolus. One of the Starlink satellites of the private US company SpaceX was on a collision course with the Earth observation satellite of the European Space Agency. In the event of a collision, thousands more scrap pieces would have been created, the already high number of which makes safe navigation and operation in Earth orbit more and more difficult and endangers the important infrastructure in space and the research missions of the space agencies.

According to Holger Krag, around 30,000 objects larger than ten centimeters are already wandering around in the earth's orbits. Above a size of one centimeter there are over 900,000 fragments and if you count the small pieces of scrap above the one-millimeter range, there are even more than 150 million fragments. All of them are residues from previous missions, obsolete upper stages and inactive satellites which, in a cascade effect, create new space debris when they collide. "The amount of debris grows enormously every year," says the ESA scientist. And with the increasing number of space missions mostly by private operators who place constellations of thousands of mini satellites in low earth orbit, the risk of collisions and further debris formation could rise again rapidly. Especially since there has been a lack of data exchange so far. Holger Krag calls for a "management of traffic in orbit". He is working on "that we can present our first ideas by the international Space Debris Conference 2021 in Darmstadt".

The Clear-Space-1 mission, part of the ESA's Clean Space Initiative, is intended to provide a pioneering solution to the waste problem. The head of ESA's Space Safety program hopes that it will spark “sustainable space travel”. In cooperation with the commercial consortium led by the Swiss startup ClearSpace, ESA wants to test a technology for active waste disposal in space for the first time and make it financially viable for private and public users. The missions of the tow truck for space debris should be affordable. “The mission is to pave the way for a future market,” emphasizes Krag.

The aim is not to remove all debris from the orbits, but first and foremost the large, critical scrap pieces that would cause hundreds of thousands more small pieces in a collision. “The big ones are the source for the little ones,” says Krag. Studies by ESA and NASA show that, in addition to avoiding waste, this is an important measure to stabilize the orbital environment. ESA launched the ADRIOS (Active Debris Removal / In-Orbit Servicing) project. The ADRIOS team provides technical expertise and advice to the ClearSpace-1 mission and the private consortium to ensure the success of the first garbage disposal technology.

The mission costs around 120 million euros. “The ESA team,” says Krag, “provides the money for this in line with the progress of the work”. And the first object that ClearSpace's garbage hunter is supposed to capture and dispose of will be a disused space object from the European Space Agency: the Vespa (Vega Secondary Payload Adapter) adapter, which will be in orbit after the flight with the ESA launch vehicle Vega 2013 around 800 x 660 kilometers in height remained. At 100 kilograms, it is a relatively small object with a simple shape and robust construction. “A good exercise object to start with,” says Krag.

The hunter developed by ClearSpace should approach the scrap piece, catch it with its robotic arms and bring it into a very low orbit, from where both should burn up in the atmosphere within a short time. That is the plan. The Swiss spin-off company, which was founded by an experienced space debris research team from the Ecole Polytechnique Fédérale de Lausanne (EPFL), wants to implement it. Luc Piguet is one of the three founders and CEO of ClearSpace.

The idea came about, he says, out of his own experience. In 2009, an EPFL team launched the Swiss Cube - a nanosatellite - for research purposes in Earth orbit at an altitude of 700 kilometers. “Exactly in the critical space debris area. There were several collision warnings, ”reports the electrical engineer, who also took part in Stanford University's“ Executive Program ”. In 2012 the team decided to get the Swiss Cube back, "but nobody wanted to pay for it," says Piguet. And there wasn't a garbage disposal company in space that could do this job. Not yet. So why not develop something yourself? Tidying up in orbit, "we saw a great need for that," says the 48-year-old. In 2017, he founded ClearSpace with space engineer Muriel Richard and industrial designer Catherin Johnson. "The Service Offer Request (SOR) for In-Orbit Servicing / Debris Removal from ESA came at the right time for us," said Piguet. The Swiss convinced the competition.

ClearSpace has meanwhile grown to 12 employees and externals as well as a team of seven at the Ecole Polytechnique Fédérale de Lausanne and at other universities in Switzerland. There is also a consortium of experienced international companies from the eight European countries participating in the ESA mission.

One of the major challenges of the mission is technology, says Luc Piguet. The ClearSpace hunter must locate the object with the help of sensors, steer it precisely and get close enough that the four gripping arms can catch the debris or the disused satellite without colliding with it. It becomes difficult with objects that rotate uncontrollably. "We have to take action before we have direct contact and only then do we pull the space junk up to our base unit and fix it there," he explains. The gripping technology is new, it can only be tried out with the first test run and rendezvous with a Vespa in space. “We have a great responsibility that this process works,” says Piguet. In addition, the technology has to cost as little as possible so that enough imitators can be found. He sees a large market for tidying up in space. "There are already 2000 satellites that have been used up and should be disposed of."

Future missions must be planned in such a way that no more space debris is created, emphasizes Holger Krag. Each country is responsible for its legislation, but it assumes that something must and will change. “Anyone who does not plan their missions sustainably will have to pay to clean up in the future. ESA wants to provide the technology for it and show that it is possible. We want to get the ball rolling, ”says Krag.

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