July 5, 2005

An innovative project to mitigate orbital pollution

Is space set to become as polluted as Earth? Orbital pollution is a reality: the amount of debris orbiting round Earth is growing, calling for a “ clean-up ” of near-Earth space. The project developed by Christophe Bonnal (CNES Launchers Directorate) seeks to contribute to sustainable development of near-Earth space by using an innovative technique to deorbit the largest items of debris. Last June, the project was honoured by the Aeroclub de France with its Prize for Technological Innovation.
19 July 2005

Mitigating space pollution

The growing problem of orbital pollution gave Christophe Bonnal the idea to develop a new device to clean up low-Earth space by deorbiting the largest items of debris.

By seeking to make space cleaner for future generations, his project takes sustainable development policy beyond its tradition terrestrial limits!
The accumulation of space debris—essentially comprising spent launch vehicle upper stages and dead satellites—can no longer be ignored, as orbital pollution is growing at an exponential rate.

The frequent collisions and subsequent breakup of larger debris is only adding to the number of useless items littering near-Earth space.
According to Christophe Bonnal, “Even in the unlikely event that all launches were stopped, the amount of debris would still continue to rise!”

Furthermore, this debris, even the smaller items, can cause huge damage to operational satellites. It is therefore vital to clean up the orbits around our planet.

Preventive measures have been taken, including the “25-year rule”, which limits the time any object is allowed to remain in orbit.

Various deorbiting solutions have already been envisaged, but each one poses the same problem of energy requirements.

An original system: tether satellites

With this problem as his starting point, Christophe Bonnal devised an innovative system to deorbit spent launch vehicle stages. The device is based on tether satellites, called “cleaners”.

The principle is simple: the “cleaner satellite” is fitted with a 30- to 50-kilometre tether, stored in a reel.

This tether is propelled towards the debris object and latches onto it. It is then cut, and the cleaner satellite and debris separate by reaction.

The debris falls back towards the atmosphere and burns up, while the cleaner satellite climbs towards the next item for deorbiting. As so the process continues.
In this way, each debris item actually helps the cleaner satellite to catch the next one. The original feature of the procedure lies in this chain reaction, which effectively dispenses with the need for satellite propulsion and makes it possible to deorbit around 50 debris items.

The validity of all theoretical concepts and technical aspects of the project have already been demonstrated.
Christophe Bonnal is thinking about the future of his project: “Why not extend it as part of a large-scale cooperation initiative to produce an international environmental satellite?”

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