Last week I blogged about the space debris problem. Today I’m blogging about technologies being developed and demonstrated to clean up space debris.
Several methods for the removal and de-orbiting of debris have been proposed so far, classified as either contact – for example, a robotic arm, a net, an electrodynamic tether – or contactless – for example, laser or “ion beam shepherd.”
Researchers at Tohoku University and Australian National University are developing an ion beam shepherd method of debris removal, which would use a plasma beam ejected from a satellite to impart a force to the debris, thereby decelerating it, which would result in the debris falling to a lower altitude, entering Earth’s atmosphere, and burning up.
Astroscale, a company founded in 2013 by a Japanese information-technology entrepreneur, proposes “to aid in the removal of orbital debris through the provision of End of Life and Active Debris Removal services.” A few years back, the company launched a 25-kilogram microsatellite designed to measure sub-millimeter-size debris in low-Earth orbit. The mission failed. The company plans to launch another debris-removal mission next year, designed to demonstrate capabilities for target search, target inspection, target rendezvous, and non-tumbling and tumbling docking. As far as I can tell, the company’s web site does not provide any information on who is paying for these demonstrations.
A company called Tethers Unlimited has developed three different approachesto space debris removal:
- “Terminator Tape,” a 250 meter long conductive tape, is designed to de-orbit microsatellites (less than 50 kilograms) operating at altitudes of less than 1000 kilometers. (I am not going to explain how this thing works – go to the web site.) The company has developed several Terminator Tape modules: theCubeSat Terminator Tape (CSTT),sized for cubesats; the NanoSat Terminator Tape,sized for large nanosats to small microsats (less than 100 kg); and the MicroSat Terminator Tape, sized for microsats less than 200 kg.
- “Terminator Tether,” which is designed to use“active electron emission technologies to greatly increase the electrodynamic forces, enabling it to deorbit most LEO [low Earth orbit] spacecraft with in a period of several months.The company says it has demonstrated this technology, but it does not provide details about the demonstration on its web site.
- “GRASP” – Grapple, Retrieve, And Secure PayloadTechnology for Capture of Non-Cooperative Space Objects – “a deployable net technology that enables small satellites to capture and manipulate space objects such as orbital debris, small asteroids, and defunct spacecraft.”
Earlier this month, Tethers Unlimited, TriSept. Corp., Millennium Space Systems, and RocketLab USA announced that they have formed a partnership to develop a mission called Dragracer, designed to demonstrate Terminator Tape. Scheduled to be launched next year, this mission will involve placing a module on a smallsat that can unwind a stretch of electrically conductive tape that can capture a dead satellite. (The company says it already has tested Terminator Tape on several space missions, but details not available on the company’s web site.)
In June 2018, a consortium of European aerospace companies launched an experimental space-debris-removal satellite from the International Space Station. The RemoveDEBRIS satellite featured two active-debris-removal technologies developed by Airbus: a net and a harpoon. This project was funded by the European Union. In September 2018, the RemoveDEBRIS net was demonstrated. A cubesat target representing an element of space debris was launched from the RemoveDEBRIS spacecraft and targeted by the net at a distance of several meters. The cubesat was captured, and the target/net combination subsequently deorbited and burned up upon atmospheric entry.
Also in 2018, another European space-debris-removal demonstration –DeOrbitSail – was intended to deploy a 4 x 4 meter drag sail designed to change the satellite’s orbit through drag and solar radiation pressure. DeOrbitSail was successfully put into orbit, but failed to deploy.
In February 2019, the RemoveDEBRIS harpoon was fired at a panel mounted on a boom extended from the RemoveDEBRIS spacecraft, hitting and penetrating the panel.
In May 2019, Surrey Satellite Technology Ltd’s TechDemoSat-1 successfully deployed a space-debris-removal drag sail supplied by Cranfield University. According to the European Space Agency, the UK’s Technology Strategy Board and the South East England Development Agency (SEEDA funded the design of the core elements of this mission, and Surrey Satellite Technology along with partners in UK industry and funded the payload technologies.
All well and good, yes? Efforts to mitigate the space debris problem are also under way (see last week’s post). Meanwhile, I keep wondering: who will pay for debris removal?