Stephen Hawking experiencing zero gravity

Renowned physicist Stephen Hawking dies aged 76

Stephen Hawking inspired people with his work on black holes and other mysteries of the universe. Many were quick to pay tribute to the theoretical physicist who died today in the UK, aged 76.

Artist's conception of GPS Block II-F satellite in Earth orbit

DARPA looks to private sector in new space race

The US military is looking to the commercial space industry to deliver the small and inexpensive satellites to replace its current ageing and vulnerable system, and it is looking to the private sector for help.