Imagine a telescope with a camera so powerful it can photograph one human hair from a thousand miles away and you have Gaia, blasted off today on a five-year mission to unlock the secrets of the Milky Way. Gaia has been launched from Kourou in French Guiana by The European Space Agency. This satellite mission is one of the most ambitious and exciting in space history and has the potential to revolutionise understanding of the universe by building up a stunningly accurate 3D picture to map billions of stars.
Its accuracy will be so astounding that it should be able to record the stars coordinates down to an error of just seven micro-arcseconds. Brightness, temperature, composition and age of stars will all be determined, building a catalogue of astrometric precision over 5 years.
One leading expert who has been working on Gaia for 20 years compared it to Captain Cook’s voyage, which forever changed the way that human beings comprehended the shape, size and scope of the earth. Professor Gerry Gilmore of Cambridge University, is among many in the scientific community who calls Gaia, “truly a transformative mission.”
Once the picture is complete, it will, in effect, be like a time-lapse film which can be run backwards or forwards to establish the creation, and the future, of the galaxy.
As Gilmore explains, “It will allow us, for the first time ever, to walk through the Milky Way – to say where everything is, to say what everything is.” Everything will include dead stars, comets, asteroids, and planets outside of the solar system, never before recorded.
Gaia was launched by a Soyuz-STB-Fregat rocket and the €740 million “discovery machine” will now commence on the biggest astronomical survey of all time. Gaia is 200 times more sensitive than Hipparcos, its predecessor, which collected data on around 118,000 stars. To put it into perspective, according to ESA, if Hipparcos could measure an astronaut on the moon, by calculating the angle corresponding to his height, Gaia can measure his thumbnail.
At the Cote D’Azur observatory in France, Francois Mignard articulates the excitement felt by many when he notes that “within two years from now we will have the first compendium of the sky.” Metaphors such as “flood” and “avalanche” are being used to try to anticipate the amount of data that will be collated, and sorting and assessing it may take years. Some estimates put the deluge of expected information at the equivalent to 30,000 CD ROMs, or 200,000 DVDs.
Another analogy given by Jos de Bruijne, who works on the project, is to imagine all the data printed out. It would make a row of 53,542 volumes at a length of 1.3 kilometers.
Gaia will take up position at L2 where it will begin the task of repeating its observations up to 70 times, an unprecedented location marker for calculating distances between stars, as well as speed of travel, direction and motion. Gaia will also be able to assess the “wobble”, the change that occurs in stellar light when a planet crosses. This will give clues to the worlds beyond our solar system and by some estimates, may detect another 50,000 planets.
The solar system itself will be explored in great depth, right to the chilly outer edges, and including the asteroid belt that lies between Jupiter and Mars. Brown dwarves (stars that have failed to ignite) and supernovas (stars that have exploded) will all be charted in the vast sweep as a complete census is built up.
Another result of Gaia’s mission will be the ability to test Einstein’s theory of relativity. Its position at L2, is 1.5 million kilometers out from earth. This is the famous position that allows a complete observation of the entire cosmos without any interruptions from the sun, the moon or the earth. To stay in that spot, it will have to adjust incrementally every month. Telescopes on earth will assist in maintaining this accuracy, hoping to keep within 100 metres.
Toulouse is one of the six centres on stand by to start to amass and sort Gaia’s myriad measurements. The supercomputer there can carry out 6,000 billion operations per second. The scientific community is on tenterhooks and tremendously excited. Timo Prusti, a scientist with the Gaia Project, speaks for many when he says, “For every professional astronomer there’s no need to explain how fundamental Gaia is.” He goes on to explain,” Everyone knows that when you get the distances to the stars it’s the basis for all the rest of astronomy.” They simply can’t wait to get their hands on all this data.
Toulouse is the focal point for Gaia’s inception. It was created here in 1991 and led by Astrium Satellites, has involved 70 companies from 16 different countries to bring it into being. The CEO of Astrium, Eric Belanger, sums up today’s launch, and the twenty year journey to this point, by saying “What an adventure!”
Citizen astronomers are going to be encouraged to join in with the exciting developments, and several crowdfunded projects to facilitate participation will start up in 2014. The European Space Agency are running live coverage and twitter followers can see the webcast on hashtag #Gaia.
The secrets of the Milky Way are on their way to being unlocked. Understanding of the universe comes a little closer as one billion stars are on course to be mapped by Gaia.
By Kate Henderson