* Scientists from a United Kingdom-led consortium of universities are planning to explore the "inner space" of vacuums with a probe in orbit around the Earth.
The Casimir mission would seek to investigate quantum mechanics, which predicts that even a perfect vacuum should be seething with short-lived particles and forces.
European Space Agency experts will spend the next six months assessing the project against five others, all but one with UK involvement, before announcing which one will be launched as one of the so-called flexi-missions towards the end of the decade.