Spring cleaning Space
Satellites are used for many reasons be it communications, weather forecasting or research. Rapid advancements in technology have improved our quality of life however along with this, a new issue arises - overcrowding. Disposal of satellites is complicated but one innovative idea to clear the traffic may simply have them sailing away.
Space is getting crowded. An ever increasing number of satellites are orbiting near to the Earth, accompanied by thousands of fragments of their defunct predecessors and rock-ets. The risk of collision and damage (which could end up costing millions of dollars), is rapidly increasing. At a conference about space debris, the European Space Agency (ESA) set itself the goal of clearing the skies and to support research into the deorbiting of satellites.
The Surrey Space Centre (SCC - SSC) at the University of Surrey, England, has devised a simple solution: Future satellites will be equipped with large sails. At the end of a satellite's mission, within a 25-year time frame, the sail will pull it down to burn up in the Earth’s atmosphere. The sail utilises the resistance of the residual atmosphere, which exists in altitudes of up to 600 kilometers.
Carbon outriggers stabilise the sail
The sail developed in Surrey is called Inflatesail. It measures five by five meters and con-sists of a high-performance plastic foil. The sail module is smaller than a shoebox and weighs only two kilograms. However, the technology has to be not only lightweight, but also robust – and cheap. After all, it is not a part of the satellite’s main mission objective. The Inflatesail won’t be used before the satellite’s service life has expired, i.e. after 10 to 20 years. Then the following happens: First a small, inflatable mast folds out. Then the sail is extended by means of four carbon outriggers that provide stability. Once it has expanded, the sail slowly drags the satellite closer and closer to Earth, until it crashes and burns up in the atmosphere. This technology is capable of bringing objects with a weight of up to 700 kilograms down from the skies.
Long years of experience in space
The sail is unfolded by a brushless EC-max motor by maxon. The motor is combined with a GP 16 planetary gearhead, equipped with ceramic components for a long life span and to protect against corrosion. The drive has a diameter of 16 millimeters. It is built according to extremely high standards and works even in space. maxon motor relies upon its many years of experience in the aerospace industry, for example in the Mars missions and SpaceX program.
Andrew Viquerat, Research Fellow at SSC SCC: “We have been working with maxon motor for years and will continue to do so – because of the reliability of their products if nothing else. The folks at maxon have always shown interest and been really helpful, even when our wishes were slightly unusual.”
First test next year
Next year it will be seen whether the Inflatesail stands up to practical testing. It will be fired into space as a part of the QB50 nanosatellite project. There it will first serve to propel the satellite, using the solar winds. After one year, a maneuver will be initiated that is intended to result in a safe crash and burn-up in the atmosphere. The mission’s success could soon lead to a commercial application of the development and help unclutter the skies above.
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