The European Space Agency plans to launch Thursday two navigation satellites that will join two already in orbit, which will allow the agency to begin tests on its Galileo network, a rival to the American Global Positioning System, Nature reports.
The network, which will consist eventually of 27 operational and three backup satellites, will cost more than $6.93 billion.
In addition to helping with navigation, because Galileo will operate over a wider bandwidth than GPS, scientists will be able to make more accurate measurements of the Earth’s surface than now, augmenting information provided through GPS and the Russian GLONASS network.
The highly accurate clocks that might be developed for the Galileo satellites could also help scientists test theories of gravity, though whether or not those clocks will be developed is unclear given their limited commercial potential.
ESA aims to have the full system in orbit by the end of the decade.