Countdown to GAIA

Just a quick post to point out that tomorrow morning at 9.12am GMT will see the launch of the European Space Agency’s Gaia mission.  You can watch the launch live here from about 8.50 GMT. I’ll be in a meeting at 9am tomorrow morning, so I’m probably going to miss it.

Gaia arrives on the Launchpad at Kourou, French Guyana, on 13th December

I remember first hearing about Gaia about 15 years ago when I was on a PPARC advisory panel and was simultaneously amazed  by the ambition of its objectives and sceptical that it would ever get off the ground. Now its almost ready to go, so fingers crossed for a successful launch tomorrow.

Coincidentally, Gaia is among the various telescopes and observatories featured in the STFC Roadshow we put on  viewfor an Astronomy Master Class we have been putting on for local schools over the last couple of days here at the University of Sussex:

Gaia is a global space astrometry mission, which will make the largest, most precise three-dimensional map of our Galaxy by surveying more than a thousand million stars. In some sense it is the descendant of the Hipparcos mission launched in 1989, but it’s very much more than that. Gaia will monitor each of its target stars about 70 times over a five-year period. It is expected to discover hundreds of thousands of new celestial objects, such as extra-solar planets and brown dwarfs, and observe hundreds of thousands of asteroids within our own Solar System. The mission is also expected to yield a wide variety of other benefits, including new tests of the  General Theory of Relativity.

Gaia will create an extraordinarily precise three-dimensional map of more than a thousand million stars throughout our Galaxy (The Milky Way) and beyond, mapping their motion, luminosity, temperature and chemical composition as well as any changes in such properties. This huge stellar census will provide the data needed to tackle an enormous range of important problems related to the origin, structure and evolutionary history of our Galaxy. Gaia will do all this by repeatedly measuring the positions of all objects down to an apparent magnitude of 20. A thousand million stars is about 1% of the entire stellar population of the Milky Way.

For the brighter objects, i.e. those brighter than magnitude 15, Gaia will measure their positions to an accuracy of 24 microarcseconds, comparable to measuring the diameter of a human hair at a distance of 1000 km. Distances of relatively nearby stars will be measured to an accuracy of 0.001%. Even stars near the Galactic Centre, some 30 000 light-years away, will have their distances measured to within an accuracy of 20%.

It’s an astonishing mission that will leave an unbelievably rich legacy not only for the astronomers working on the front-line operations of Gaia but for generations to come. I have a feeling that there might be  a few sleepless nights tonight waiting for the launch, but I suppose astronomers should be used to that!

UPDATE: 19/12/2013 Success! Launch went smoothly, separation of the Gaia spacecraft achieved. Now we have to wait for a month or so for it to get to L2, settle itself down, and then start doing science. The first data release isn’t due for 22 months…Bon Voyage!

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