The 22-nation agency is spearheading one of several efforts to roll back the mass of space junk swirling round the planet from past missions that poses a risk to active satellites.

Aschbacher said 110 countries or entities have joined ESA's Zero Debris charter, which aims to stop any new orbital garbage being generated by 2030.

Asked whether SpaceX, whose satellites now make up some two thirds of spacecraft active in low Earth orbit, had signed up, Aschbacher said: "Not yet, but we are in discussion with them... This is a charter that keeps evolving and . . . we will keep raising the topics because they are so fundamental."