British-led mission successfully harpoons 'orbital debris'

Posted Feb 16, 2019 by Karen Graham
A British-led mission successfully tested a harpoon that's designed to spear space junk and capture it in orbit for the first time. Airbus carried out the successful experiment as part of the RemoveDebris project.
The RemoveDEBRIS satellite was released from the International Space Station on June 20  2018. The p...
The RemoveDEBRIS satellite was released from the International Space Station on June 20, 2018. The project has already carried out three experiments.
The RemoveDEBRIS mission was started in 2013 by a consortium of 10 partners across Europe, including aerospace giant Airbus .and the University of Surrey's Surrey Space Center. Airbus carried out the successful mission as a step toward cleaning up our growing junkyard of space debris orbiting the Earth.
The harpoon used in the experiment is a "small-scale version of the real thing. In 2018, Airbus tested the high-tech harpoon at the aerospace company’s facility in Stevenage, UK.
The 0.9-meter-long (3 feet.) harpoon was fired using compressed air into a panel that mimics the kinds of material used to build satellite casings. The panels on a spacecraft typically have 3,0 centimeters (1.2 inches) thick, composite-honeycomb panels made mostly of aluminum.
The latest demonstration is the project's third experiment in space. It previously used its onboard net to capture a simulated piece of debris, and then trialed its state-of-the-art LiDAR and camera-based vision navigation system to identify space junk, according to the University of Surrey.
Tackling waste material in space
There is an estimated, 8.1 million kilos (3,968,321 pounds) of junk and debris floating around in space. European and U.S. space agencies are monitoring approximately 20,000 objects as big or bigger than a baseball and 50,000 objects as big as a marble.
That number is in addition to the over 2,000 commercial and government satellites orbiting the earth at the present time. Additionally, there are an estimated 600,000 pieces of space junk ranging from 1 cm to 10 cm floating, and on average one satellite is destroyed each year.
Space debris traveling at 17,500 miles per hour can exert a powerful kinetic energy capable of significant damage upon impact. Knowing this can happen, and looking at the bigger picture, NASA scientist Donald J. Kessler proposed a scenario in 1978 called the Kessler syndrome, or Kessler Effect.
The Airbus harpoon is meant for the Moby Dick of space debris -Envisat.
The Airbus harpoon is meant for the Moby Dick of space debris -Envisat.
Kessler theorized that an increase in the number of objects in low-Earth orbit would lead to conditions where collisions between objects could cause a cascade where each collision generates space debris that increases the likelihood of further collisions.
Astronaut Tim Peake previously revealed the damage that this junk can cause on spacecraft when he shared an image of a chipped window panel on board the International Space Station (ISS) in 2016, according to the UK's Daily Mail.
There have also been collisions, like in February 2009, when an Iridium telecoms satellite and Kosmos-2251, a Russian military satellite, accidentally collided. Scientists are also worried about two orbital sites that have become very cluttered - low Earth orbit which is used by satnav satellites, the ISS, China's manned missions and the Hubble telescope, among others.
The other is the clutter that is growing in geostationary orbit. This orbital area is used by communications, weather and surveillance satellites that must maintain a fixed position relative to Earth
The AirBus miniature harpoon
The AirBus miniature harpoon
RemoveDebris system works "in the blind"
It's one thing to see the object you are trying to hit with a spear - but to throw a harpoon at a space object without seeing it can be tricky.
The experiment was actually done "in the blind," reports the BBC, in a part of the demo satellite's flight-path that was out of contact with controllers on the ground at Surrey Satellite Technology Ltd, also in Guildford.
Space Shuttle Endeavour had a major impact on its radiator during STS-118. The entry hole is about ...
Space Shuttle Endeavour had a major impact on its radiator during STS-118. The entry hole is about ​1⁄4 inch, and the exit hole is twice as large.
Basically, the whole operation was automated, meaning the demonstration relied on pre-loaded commands. Even this issue is being worked on with the project testing computer vision systems that can identify and track targets. In time, with computer vision technology, it will be just a matter of firing the harpoon at an object and reeling it in, which is what the satellite demonstrated.
The last test of the RemoveDebris satellite will be to deploy the big membrane to accelerate its fall to Earth. The end-of-mission "drag sail" will help in reducing the satellite's altitude, pulling it down so it will eventually burn up in the atmosphere. "It's now really up to our partners in the industry as to where they take these technologies," said Professor Guglielmo Aglietti, from the University of Surrey in Guildford - the principal investigator on the mission.
"You see the harpoon hit the target in the center, as expected and get embedded. The target comes off the boom, but that's not a problem because the harpoon is tethered; it's attached to a wire. So all elements worked," he told BBC News.