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Gaia 'billion star surveyor' set for launch | Gaia 'billion star surveyor' set for launch |
(about 7 hours later) | |
Europe is about to launch the Gaia satellite - one of the most ambitious space missions in history. | Europe is about to launch the Gaia satellite - one of the most ambitious space missions in history. |
The 740m-euro (£620m) observatory is going to map the precise positions and distances to more than a billion stars. | The 740m-euro (£620m) observatory is going to map the precise positions and distances to more than a billion stars. |
This should give us the first realistic picture of how our Milky Way galaxy is constructed. | This should give us the first realistic picture of how our Milky Way galaxy is constructed. |
Gaia's remarkable sensitivity will lead also to the detection of many thousands of previously unseen objects, including new planets and asteroids. | Gaia's remarkable sensitivity will lead also to the detection of many thousands of previously unseen objects, including new planets and asteroids. |
The European Space Agency (Esa) satellite is being sent up on a Soyuz rocket. | The European Space Agency (Esa) satellite is being sent up on a Soyuz rocket. |
Lift-off from the Sinnamary launch complex in French Guiana is scheduled for 06:12 local time (09:12 GMT). | Lift-off from the Sinnamary launch complex in French Guiana is scheduled for 06:12 local time (09:12 GMT). |
Gaia will be released from the rocket's upper-stage just over 40 minutes later. | Gaia will be released from the rocket's upper-stage just over 40 minutes later. |
The intention is to put it on path to an observing station some 1.5 million km from the Earth on its nightside - a journey that will take about a month. | The intention is to put it on path to an observing station some 1.5 million km from the Earth on its nightside - a journey that will take about a month. |
Gaia has been in development for more than 20 years. | Gaia has been in development for more than 20 years. |
It will be engaged in what is termed astrometry - the science of mapping the locations and movements of celestial objects. | It will be engaged in what is termed astrometry - the science of mapping the locations and movements of celestial objects. |
To do this, it carries two telescopes that throw light on to a huge, one-billion-pixel camera detector connected to a trio of instruments. | To do this, it carries two telescopes that throw light on to a huge, one-billion-pixel camera detector connected to a trio of instruments. |
Gaia will use this ultra-stable and supersensitive optical equipment to pinpoint its sample of stars with extraordinary confidence. | Gaia will use this ultra-stable and supersensitive optical equipment to pinpoint its sample of stars with extraordinary confidence. |
By repeatedly viewing its targets over five years, it should get to know the brightest stars' coordinates down to an error of just seven milli-arcseconds. | By repeatedly viewing its targets over five years, it should get to know the brightest stars' coordinates down to an error of just seven milli-arcseconds. |
"This angle is equivalent to the size of a euro coin on the Moon as seen from Earth," explained Prof Alvaro Gimenez, Esa's director of science. | "This angle is equivalent to the size of a euro coin on the Moon as seen from Earth," explained Prof Alvaro Gimenez, Esa's director of science. |
Gaia will compile profiles on the stars it sees. | Gaia will compile profiles on the stars it sees. |
As well as working out how far away they are, the satellite will study their motion across the sky. | As well as working out how far away they are, the satellite will study their motion across the sky. |
Their physical properties will also be catalogued - details such as brightness, temperature, and composition. It should even be possible then to determine their ages. | Their physical properties will also be catalogued - details such as brightness, temperature, and composition. It should even be possible then to determine their ages. |
And for about 150 million of these stars, Gaia will measure their velocity either towards or away from us. | And for about 150 million of these stars, Gaia will measure their velocity either towards or away from us. |
This will enable scientists to use them as three-dimensional markers to trace the evolution of the Milky Way, to in essence make a time-lapse movie that can be run forwards to see what happens in the future, or run backwards to reveal how the galaxy was assembled in the past. | This will enable scientists to use them as three-dimensional markers to trace the evolution of the Milky Way, to in essence make a time-lapse movie that can be run forwards to see what happens in the future, or run backwards to reveal how the galaxy was assembled in the past. |
And because Gaia will track anything that passes across its camera detector, it is likely also to see a colossal number of objects that have hitherto gone unrecorded - such as comets, asteroids, planets beyond our Solar System, cold dead stars, and even tepid stars that never quite fired into life. | And because Gaia will track anything that passes across its camera detector, it is likely also to see a colossal number of objects that have hitherto gone unrecorded - such as comets, asteroids, planets beyond our Solar System, cold dead stars, and even tepid stars that never quite fired into life. |
"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. It is truly a transformative mission," said Prof Gerry Gilmore from Cambridge University, UK. | "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. It is truly a transformative mission," said Prof Gerry Gilmore from Cambridge University, UK. |
A key early moment in the endeavour comes just an hour after launch. | A key early moment in the endeavour comes just an hour after launch. |
It is at this point that Gaia must deploy the sunshield that will protect its optics from any swings in temperature and the disturbance this would introduce to the measurement task. | It is at this point that Gaia must deploy the sunshield that will protect its optics from any swings in temperature and the disturbance this would introduce to the measurement task. |
The unfurling is achieved through the simultaneous firing of 12 pyrotechnic devices. These will split the bolts that were used to lock the shield in a stowed configuration for launch. | The unfurling is achieved through the simultaneous firing of 12 pyrotechnic devices. These will split the bolts that were used to lock the shield in a stowed configuration for launch. |
It will be a high-anxiety event. A failure to "flower" would kill the mission. | It will be a high-anxiety event. A failure to "flower" would kill the mission. |
By the end of the decade, the Gaia archive of processed data is expected to exceed 1 Petabyte (1 million Gigabytes), equivalent to about 200,000 DVDs of information. | By the end of the decade, the Gaia archive of processed data is expected to exceed 1 Petabyte (1 million Gigabytes), equivalent to about 200,000 DVDs of information. |
This store is so vast that it will keep professional astronomers busy for decades. | This store is so vast that it will keep professional astronomers busy for decades. |
It means however that there will be ample scope as well for citizen scientists to mine Gaia's data to make their own discoveries, and a number of crowdsourcing projects to facilitate this activity will get under way next year. | It means however that there will be ample scope as well for citizen scientists to mine Gaia's data to make their own discoveries, and a number of crowdsourcing projects to facilitate this activity will get under way next year. |
Gaia has been born from an enormous industrial effort. Led by Astrium satellites in Toulouse, France, it has involved more than 70 companies in 16 countries. | Gaia has been born from an enormous industrial effort. Led by Astrium satellites in Toulouse, France, it has involved more than 70 companies in 16 countries. |
"Although contracts weren't signed until 2006, the Gaia idea actually began in 1991. That's astonishing - 1991, and now we're about to launch this remarkable spacecraft. What an adventure!" commented Astrium CEO Eric Beranger. | |
Jonathan.Amos-INTERNET@bbc.co.uk and follow me on Twitter: @BBCAmos | Jonathan.Amos-INTERNET@bbc.co.uk and follow me on Twitter: @BBCAmos |