Spacecraft are all shiny and new when they leave Earth but being up in space can do a number on them, resulting into bits and pieces of junk flying around. The European Space Agency's Clean Space initiative is looking to lessen the amount of space junk and it's turning to fishing nets to get the job done.
Nets in space? Given their structure, a net does good work trapping anything it targets. In the case of Clean Space, it's coming after old satellites and other spacecraft debris flying in space. Kjetil Wormnes and colleagues at the ESA recently tested how nets would fare in cleaning up space and found that the method is highly effective.
To observe how nets would behave in orbit, the ESA launched an aircraft and had it fly parabolic arcs to simulate short periods of weightlessness. Nets were then shot out of a compressed-air ejector, aimed at a scale model of a satellite. Twenty nets were shot out at varying speeds over the course of two days through 21 parabolas. The nets were packaged inside paper cartons, with each corner weighted to facilitate entanglement around the model satellite.
"The good news is they worked extremely well - so much so that the nets usually had to be cut away with a knife before we could shoot again," said Wormnes.
To recreate weightlessness, the Falcon 20 aircraft used in the experiment was flown in such a way that, for 20 seconds, it falls through the sky and effectively cancels out gravity within the aircraft.
The experiments were recorded using four high-speed HD cameras, allowing the ESA to observe the net tests thoroughly to assess the simulation tool developed by the agency. Information gleaned from the tests will aid in the development of full-sized nets for debris-removal missions.
According to the tests, nets with thinner, spun designs were more effective than their thicker, woven counterparts.
The e.Deorbit mission is set to launch in 2021 to test how feasible it is to remove large debris in space, helping control the amount of flying objects present in busy orbits.
The ESA has not decided yet on a method of removal but the Clean Space initiative is considering the use of harpoons, ion beams and robotic arms, on top of nets, to lessen debris in space. One advantage nets have over other methods is that they are capable of handling a wider range of rotation rates and shapes in targets.