In the movie “Space Junk 3D”, the Head of NASA’s Orbital Debris Office guides the public via a giant 3D screen through the threats of collision hazards and the stunning images of Earth orbits, polluted with thousands of space debris[i].
Yet unfortunately, this is not just science fiction.
The issue of “space junk” or better, “space debris”, has become an increasingly pressing problem. Since the launch of the first artificial satellite Sputnik, in 1957, more than 6000 satellites have been put into space. Through the years, continued launches, dead satellites and some collision events have originated thousands of fragments, which now threaten the life of the satellites in orbit and even put at risk the very possibility to access space for present and future generations.
Indeed, the smallest debris can turn to be a potentially destructive weapon, given the rotation speed and the hostile environment in which satellites are located. In Low Earth Orbit, where objects rotate at 7.8 km per second, even if the debris population remains as it is today, the level of fragmentation will continue to grow exponentially[ii].
So, what would be an effective solution?
In the first place, greater awareness of where the debris are located can enhance the possibility to adopt avoidance maneuvers. Secondly, States should take measures to avoid dead satellites staying in orbit for decades, like return to Earth or displacement either in the upper “garage” orbits or in the upper atmosphere, where they will disintegrate. However, the adoption of such measures is not imposed by any binding Treaty and is accordingly left to the goodwill of States. Also, such maneuvers require carburant, thus reducing the lifespan of space objects.
The enthusiasm of the international space community was therefore triggered when last February the Swiss Space Center announced the development of “CleanSpace One”, a satellite equipped with a grappling arm able to track down, grab and pull the hazardous space objects, in order for them to disintegrate in the upper atmosphere. Within the next five years the system should be ready to interject its first target, which will be either Swisscube , or TIsat, both Swiss cubesats[iii]. However, despite some studies having already illustrated the technical feasibility of what should be the future commercial space vacuum cleaner[iv], the system raises several concerns from legal, technical and commercial perspectives.
From a space law point of view, the system seems consistent with the “Space Debris Mitigation Guidelines” adopted by the UNCOPUOS (United Nations Committee on the Peaceful Uses of Outer Space) and endorsed by the UN General Assembly in 2007. However, although they represent a valuable reference, the States are not under any binding obligation to “clean up their mess” in outer space. Moreover, a number of legal problems will have to be addressed if the removal concerns satellites belonging to other states. This could cause problems of ownership (it is not always possible to determine which is the launching state of a space debris), but also weaponization issues (as the prototype, being able to destroy another satellite by de-orbiting it, could be potentially used as a “space weapon”) and issues of international liability for damages, especially in the case of failure or downstream damages to other satellites. Also, if the dead satellite or debris is American or includes US parts, the question might arise whether the obtention of an export license is necessary. Additional problems would arise if the removal is addressed against a military or governmental satellite[v]. The initiative therefore needs to be accompanied by a clear set of rules, taking into consideration the UN Treaties and principles on outer space.
On a technical point of view, other problems will have to be faced: CleanSpace One will have to get onto the same orbital plane as the target (which will be moving at high velocity and could be rotating), grab it and de-orbit it. In addition, for the reentry in the upper atmosphere, surviving loads could cause great risk on the ground to populations, buildings and natural ecosystems[vi]. There is also a risk that thousands of new debris will be added into active orbits, with potentially serious consequences for the space environment and the existing missions. Finally, the sustainability (also on an economic point of view) of the launch of such a system will mean that the removal may be rather expensive, and the role of insurances in such a payment might have to be discussed.
So, can CleanSpace One really be a valuable active solution to the space debris issue? While the system is still a prototype, the idea of an “active” removal system seems to many to be the ultimate effective solution. Especially when big satellites, like Envisat, end their lifetime and cause a number of worries to the satellites in the nearby orbits. However, this cannot be the only solution. International cooperation and the general adoption of practices like the re-entry of satellites are essential to guarantee the long-term sustainability of the space environment and the free access to space for present and future generations. While we become more and more reliant on space, the possibility that it becomes a more and more limited resource should push to a wide agreement on a new binding engagement on space debris mitigation, ensuring the sustainable use of space in the benefit and interest of all countries and of present and future generations.
[i] “Space Junk 3D”, Big Movie Zone, http://www.bigmoviezone.com/filmsearch/movies/index.html?uniq=741
[ii] While 15.000 objects larger than 5 cm in Earth orbits can be tracked by radar and telescopes from the ground[ii], smaller space debris are not tracked. However craters on returned space hardware and in-situ impact detectors resulted in estimation that they might be in the several hundreds of thousands. See: Castronuovo M., “Active Space Debris Removal- A Preliminary Mission Analysis”, in Acta Astronautica, vol.69, issues 9-10, November-December 2011, p.848; http://www.esa.int/esaMI/Space_Debris/SEM2D7WX3RF_0.html; Rosanelli R., Vega: A new younger brother in the European launcher family, in the International Security Observer, 13/02/2012, http://securityobserver.wordpress.com/2012/02/13/vega-a-new-younger-brother-in-the-european-launcher-family/
[iii] Hatamoto M., “Swiss Unveil CleanSpace One Satellite to Clean Up Space”, Daily Tech, Science,16th February 2012, http://www.dailytech.com/Swiss+Unveil+CleanSpace+One+Satellite+to+Clean+up+Space/article24014.htm
[iv] Castronuovo M., “Active Space Debris Removal- A Preliminary Mission Analysis”, cit.
[vi] Wu Z., Hu R., Qu X.,Wang X., Wu Z., “ Space Debris Reentry Analysis Methods and Tools“, in Chinese Journal of Aeronautics, vol. 24, issue 4, August 2011, p. 387.