Harpoons May Be Used By ESA To Clear Earth’s Orbit Of Space Junk

Gerard LeBlond for www.redorbit.com – Your Universe Online
The European Space Agency (ESA) is embarking on an age old practice of using harpoons for the future goal of clearing orbits of tumbling satellites and other hazardous space junk.
The Earth’s orbit is filled with decades of launched satellites that are no longer being used, along with other space debris that pose a collision threat with ongoing missions. There are more than 17,000 trackable objects floating in Earth’s orbit. While the majority of these objects are larger than a coffee cup, even pieces of debris as small as a nut can cause catastrophic damage if it collides with a working satellite.
Our satellites monitor the planet daily, floating in the lower orbit and the only way to protect collision is to remove the space debris such as upper rocket stages and out-of-service satellites from the orbit. These large objects pose a substantial threat to the working satellites we as a society depend on in our everyday life.
The large objects weigh tons, and if a collision occurs, or if it explodes from left over fuel or partially charged batteries heated by the sun, it would leave a dangerous debris cloud floating within the orbit. This cloud could eventually impact a satellite or cause a chain reaction, potentially destroying multiple satellites.
ESA has come up with a plan for avoiding such a catastrophe. The Clean Space initiative (mission e.DeOrbit) is set to launch in 2021. It consists of sensors and automatic controls that will identify and locate potentially dangerous debris. The difficult element of the mission was how to secure the hazardous space junk. Many solutions were considered, such as using a throw net, clamping mechanisms, robotic arms and a tethered harpoon.
Airbus Defence and Space in Stevenage, UK, has previously considered the harpoon concept. This system requires a high-energy impact into the target which would be powerful enough to pierce the structure, then reel it in.
Tests have been done with a prototype harpoon to assess the penetration and strength needed to pull in the debris, as well as if any additional fragments may have been generated that would threaten the mission. The next step for the ESA is to build a prototype version of the harpoon and mechanisms for the mission.
Once the prototype is completed, there will be three stages using computer models, analysis and experiments, ending with a full demonstration.
The preliminary design of the harpoon has a penetrating tip to pierce the debris, a crushable cartridge to help embed the tip into the debris and barbs on the tip to keep the harpoon attached while the space junk is being reeled in. This is just one concept of clearing space debris ESA is exploring.