Archive for December 18, 2013

Countdown to GAIA

Posted in The Universe and Stuff with tags , , , on December 18, 2013 by telescoper

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

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!

Viva Elsewhere…

Posted in Biographical, Education with tags , , on December 18, 2013 by telescoper

I just came back from a meeting of the Heads of  the science Schools here at the University of Sussex where, among other things, we discussed PhD completion rates across the University. I sat there smugly because ours in the School of Mathematical and Physical Sciences are pretty good. The meeting started at 10am which also happens to have been the starting time for a PhD examination in at Cardiff University involving my (former) student Ian Harrison. I would have liked to have been there, but unfortunately I have several appointments today in Sussex so couldn’t make it.

It’s not normal practice for the supervisor of a PhD to be present at the examination of the candidate. The rules allow for it – usually at the request of the student – but the supervisor must remain silent unless and until invited to comment by the examiners. I think it’s a very bad idea for both student and supervisor, and the one example that I can recall of a supervisor attending the PhD examination of his student was a very uncomfortable experience.

I always feel nervous when a student of mine is having their viva voce examination, probably because I’m a bit protective and such an occasion always brings back painful memories of the similar ordeal I went through twenty-odd years ago. Although I have every confidence in Ian, I can’t help  sitting in my office wondering how it is going. However, this is something a PhD candidate has to go through on their own, a sort of rite of passage during which the supervisor has to stand aside and let them stand up for their own work. Usually, of course, I would be there for the event (if not actually present in the examination room), but now I’m a considerable distance away it feels a bit strange.

I’ve actually blogged about a paper of Ian’s already. He finished his thesis well within the usual three-year limit and has moved to the Midlands (Manchester, to be precise) to take up a postdoctoral research position there.  He’s not technically allowed to call himself Doctor Harrison yet, but I’m sure it’s just a matter of time. In the words of Miss Jean Brodie, my students are, without doubt, la crème de la crème.

It’s now 11.45. Fingers crossed for some news soon…

UPDATE: 13.00. Still no news…

UPDATE: 13.07. Congratulations, Dr Harrison!