Space Junk, Time To Clean The Mass Of Debris Orbiting Earth
From bulky satellite corpses to tiny metal splinters, the Earth is surrounded by a cloud of space debris. But now there are plans for a groundbreaking clean-up.
UEDEM — Two non-descript containers in this northwest German town help track the dangers of collisions in outer space. The "Space Situational Awareness Center," operated by the German Federal Armed Forces does not, however, protect Germany and the rest of the world from little green men or other space villains with laser guns. The dangers mentioned above are simply made of debris.
More than 20,000 objects, with a diameter of at least 10 centimeters (4 inches), are orbiting earth in uncontrollable circuits. These include broken satellites, burned-out rocket fuel cells, and general debris from collisions or targeted destruction procedures. In addition to that, you have about 750,000 pieces measuring 1 centimeter (0.4 inches) that are not detectable from Earth.
For starters, all of this debris constitutes a major danger to the nearly 1,500 active satellites currently orbiting the planet. The last crash happened in 2009 when a Russian Kosmos satellite collided with a U.S. Iridium satellite. The result was some 10,000 fragments adding to the considerable debris already in place.
"Sixty years of space exploration have led to a lot of "traffic" circulating above the Earth," says Colonel Thomas Spangenberg, military head of operations at Uedem's Space Situational Center. All that traffic also means an increased risk of accidents, especially when there are plenty of rogue "drivers' and no real rules of the highway nor any reliable roadway repair service. All attempts to contain the amount of debris or force it into predictable orbits have failed up until now. Plans to tow away the wreckage and dispose of it somehow have also failed to take off due to the lack of available technology, funding and political will to seriously pursue them.
"During normal traffic accidents on the motorway the police will block off that portion of motorway," says Gerald Braun, civilian head of operations at the Center, which is jointly operated by the German Federal Air Force and the German Aerospace Center (DLR). "But that is impossible up there. It's an active high-speed traffic system, so nothing can be stopped."
Braun and Spangenberg have only one option, namely to prevent the worst from happening.
We're flying blind
Predicting collisions is like poking around in the dark. "At the moment we are dependent on the Americans and their global network, just like the rest of the Western hemisphere," says Spangenberg. At least 30 different radar stations and optical telescopes aid the U.S. in tracking the orbits of an estimated 30,000 objects. Some 18,000 of these satellites and pieces of debris are recorded in a catalogue that anyone can access. The rest is top secret, though some of the confidential materials are shared with Transatlantic partners.
One of the pieces that Americans do not share information about, is the so-called "unknown" object, which is currently worrying officials at the Center since it is scheduled to pass quite close to a German civilian observation satellite within the next two days. "Unknown" is believed to one of these top secret objects, perhaps a spy satellite, a metal splinter or a burned out rocket fuel cell.
"We have no idea what is heading towards us," says Gerald Braun "We have no access to the size of the object nor the data in the catalogue."
But this kind of predicament is supposed to change, as Germany has announced plans to monitor all space junk by themselves in future.
The name of that particular project is Gestra. The DLR and Air Force want to be able to independently track the orbits of satellites and debris between 500 to 1,200 kilometers (310-745 miles) in altitude through the use of an experimental, modular as well as mobile observation radar system located within the containers at Uedem. One of the containers sends radar beams into space while the other container, situated 100 meters (328 feet) apart from one another, receives the reflected signals and analyzes them.
Gestra is supposed to be up and running within the next year, though the Center will also have to learn how to process the received data. Tens of thousands of warnings of potential collisions, based on information from the Center's and U.S. authorities, are already collated at the German site each year. The information is filtered, analyzed and lands, if the danger is considerable, in room 109, the operational heart of the Center. Critical situations arise once or twice a month: if a collision is imminent, the satellite operator is contacted and kindly asked to perform evasive maneuvers.
"In the future, this data will be analyzed in a fully automated process," says Braun. "Otherwise it will become impossible to tackle the task."
It's not clear if Gestra's resolution capacity will be even stronger than the Americans', who can identify objects with a diameter of 10 centimeters. But even if Gestra could manage to locate objects as small as five centimeters, it would not solve all problems: even an object of only three centimeters can cause devastating damage. "As opposed to aviation space, of which we have an absolute map at any given time, the space surrounding Earth is unchartered. And we never will be able to charter it anyway," says Braun. "In the end, we are flying blind."
All of this is a warning of the importance of avoiding the creation of additional space junk. Only a few countries, such as France for example, have legislation in place to support the prevention of creating space debris. Even Germany is behind the times. Instead, such vague policy suggestions have been made as lowering satellite orbits at the end of their lives to 520 kilometers. The Earth's atmosphere is still dense enough at that height that the satellite is slowed down and, over a period of 25 years, slowly incinerates and burn up. In addition to that, pressure tanks should be bled dry, batteries discharged and fuel cells dried up completely. In short, anything explosive needs to be stabilized prior to descent.
But junk prevention costs money and very few satellite operators want to pay for that. "We need politicians to enforce guidelines," says Holger Krag, head of the Bureau for Space Debris with the European Space Agency in Darmstadt. "But the responsible space exploration committee of the United Nations has not passed a law in decades because various states block each other."
So, there is only refuse collection. Ideas and initiatives for getting rid of space junk are based on this simple principle. The European Union has allocated 15 million euros for a "Remove Debris' project, which aims to prove that defective satellites can be tamed by utilizing nets or harpoons. The captured satellite could then be dragged to a lower orbit to incinerate.
But such innovations are futile on their own, says DLR manager Braun. "It is essential that we have a picture of our own about what is going on up in space."