A STG2 billion ($A3.
72 billion) European probe that will map more than a billion stars in 3D is due to be launched into space.
British scientists and engineers have played key roles in the design and construction of the spacecraft, called Gaia.
The two-tonne robot is expected to blast into orbit on a Russian Soyuz rocket from the European space port in French Guiana on Thursday.
Its five-year mission is to pinpoint many millions of stars with unparalleled precision, and discover thousands of previously unknown objects, including exploding stars, planets orbiting other suns, and nearby asteroids.
Scientists also hope Gaia will yield clues about mysterious Dark Matter and Dark Energy.
The observatory will operate from a stable location 1.5 million kilometres from the Earth known as the L2 Lagrangian point.
Situated with the Earth shielding it from the Sun, the craft will be perfectly placed to observe the wider universe. As it spins slowly, two telescopes will sweep across the entire sky and simultaneously focus their light on the largest digital camera ever put into space.
The flood of data beamed back to Earth will be enough to fill more than 30,000 CD-ROMs.
“The results from Gaia will revolutionise our understanding of the cosmos as never before,” said Professor Gerry Gilmore, from Cambridge University, the UK’s principal Gaia investigator.
“Our understanding of what’s out there has been driven by looking at what we can see. We’ve never had a genuine opportunity to look at everything, to know what’s there, and to know where they are in relation to each other.
“We don’t even know how much we don’t know – there are sure to be objects out there that don’t even have names yet, since we don’t yet realise how strange they are.”