GAIA – How to take a Galactic Census
06/07/2011 @ 7:30 pm - 11:00 pm
Gaia is ESA’s most ambitious stereoscopic astrometric mission to date. It aims to improve Hipparcos’ legacy by measuring positions and proper motions for 1 billion stars in our Galaxy (as opposed to Hipparcos’ approximately 130000 stars) by continuously scanning the sky for 5 years with its two 1.45 x 0.5m main telescopes. Complemented by blue and red photometric measurements and high resolution radial velocities for stars brighter than V=17 the final Gaia catalogue will be the largest and most precise 3-dimensional chart of our galaxy. Not restricted to stars, the all-sky nature of the mission will see millions of quasars and a comprehensive survey of solar system objects added to the catalogue.
The accuracy requirements of the mission present significant technological, calibration and software challenges.
In this talk I will give a brief introduction to the mission, how those challenges are being met and the scientific rewards we hope to gain from this endeavour.
All so that we can more accurately find ourselves somewhere in the uncharted backwaters of the unfashionable west end of the Orion Spiral Arm?… To use the famous catch-phrase of a certain physicist: Amazing!
Be Amazed! All at our usual venue:Fellows Morton and Clayton
54 Canal Street
Nottingham, NG1 7EH
Telephone: 0115 9506795
To find us, go through to the back of the pub and we’re up the vastly smaller spiral of the restaurant staircase black helix. Just ask one of the friendly bar staff for NLUG if lost.
Food is also served through into the evening.
Pan-galactics and All welcome!
We were indeed amazed!
We were treated to an absorbing evening of extremes for a project spanning over a decade in the making that will push the frontiers of science, engineering, measurement, data processing, and celestial mapping and astrometrics, boldly into as yet uncharted territories. All expertly presented in terms that even my 4 beers could understand!
Especially impressive are the extremes to which all aspects of the project have been pushed so as to gather as much data as precisely and as quickly as is possible, and all with as near complete reliability as possible. Yet the basis for the measurements are exactly as was done in the early days of navigation with a sextant and a mariner’s keen steady eye. However, the ‘sextant’ in this case is an incredible 3.8-metre diameter optical bench of ultra-stable silicon-carbide, and the eye in this example has over 1 billion pixels interpolated to give a position accuracy of better than 1000-th of a single pixel! All thrown into the harsh environment of space so as to avoid the blurry fuzziness of the Earth’s dirty turbulent atmosphere. “Gaia’s measurements will be so accurate that, if it were on Earth, it could measure the thumbnails of a person on the Moon” (Gaia factsheet). The spacecraft’s five year mission is to loiter around the sun-earth L2 point to map about 1% of the Milky Way Galaxy, and anything and everything else that might be found.
I particularly liked the processing strategy to model the sensor operation along with whatever expected defects to then compare the results with the raw measurement data to then iteratively better model the entire sensor operation and so calibrate out all the defects. Phew! A very neat work-around to work around the unknown!
Also impressive are the requirements here on the ground for the databases and supercomputing data processing to do the number crunching to produce the final multi-billions entries catalogs.
To use another famous catch-phrase: Fascinating!
Further details about the project are on: ESA: Gaia overview
Many thanks to Dr D J Fyfe of Leicester University for giving an excellent talk.
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