Legal opinion on the Chinese Anti-Missile Test

Sir,

You report that Tony Blair, the UK prime minister, believes the Chinese anti-satellite missile test does not contravene international law ("China denies starting space arms race", January 20). Certainly the 1967 principles treaty on the use of outer space prohibits putting nuclear and other weapons of mass destruction in orbit and, by saying nothing about other military uses, the treaty probably permits them.

But the treaty also stipulates that states bear international responsibility for national activities in outer space (Article VI), that they must consult before risking harmful interference with the activities of others (Article IX) and are internationally liable for damage caused by their space objects (Article VII). In other words, the treaty establishes a framework for a duty of care. What has happened needs to be judged against this framework.

The target was, it seems, a satellite with a mass approaching one tonne and a lateral velocity in relation to the earth's surface of 7km per second. The impact with the missile will no doubt have converted it into a cloud of debris both within its orbital path and elsewhere. A few grammes of debris at that velocity could take out another satellite or kill an astronaut. Below 1cm in diameter, the bits are too small to be tracked by radar and so are an unseen hazard. The potential for damage to other satellites in this relatively crowded part of the sky is obvious. It also closes the orbit to other use as the debris smears itself around the orbital path. It appears that the People's Republic failed to consult before initiating the test and to that extent at least has contravened international law.

This example of thoughtless target practice illustrates, however, the urgent need for nations with space systems to agree a more developed legal framework for the duty of care outlined in the 1967 treaty. In particular it should oblige states to do all they can to preserve orbital space in a condition usable by all, before space flight becomes too hazardous to be undertaken and the earth, like Saturn, acquires a system of rings rather less attractive than those around Saturn.

Tony Ballard,
Chairman,
UK National Point of Contact,
European Centre for Space Law