ESA Aims Gaia

It is a long time since I was a student but having caught Professor’s Gerry Gilmore’s talk at the recent UKSpace conference, I’d guess that not many of the current cohort at Cambridge University’s Institute of Astronomy, miss his lectures. Like all enthusiasts for their subject, Prof. Gilmore was able lift up the audience and carry us with him; that makes learning fun.

A member of the original European Space Agency (ESA) Gaia study team, Prof. Gilmore introduced me – I must admit, outside of the name I knew very little about this project – to this incredibly ambitious mission.

Building on the previous Hipparcos mission which produced a high precision map of 100,000 stars, Gaia launched in December 2013 with the objective of building a three-dimensional map of the Milky Way; the galaxy that contains our home planet and the rest of the solar system.

If it is successful in this – which will mean mapping the position of around one billion stars – Gaia data will be able “to quantify the early formation, and subsequent dynamical, chemical and star formation evolution of the Milky Way Galaxy”. That’s not an insubstantial objective.

Terms that describe the very large (and very small or very unusual etc.) are used commonly now and hence often can lose their impact. A ‘billion’ may not even seem a big number anymore but in attempt to put it into context; a billion seconds is equivalent to thirty years and stacking one billion dollar bills on top of each other, would create a tower nearly seventy miles tall!

Gaia has a lot of stars to map.

To get the best view (I’m sure that’s not the best scientific way of putting it), Gaia is orbiting around a point in space which is 1.5 million kilometres from Earth, in the direction away from the Sun. More accurately, it is in a Lissajous-type orbit around the L2 Lagrange point but you may need to attend Prof. Gilmore’s classes to understand more. Put slightly more simply, by being in that orbit, Gaia joins us on our trip around the Sun whilst being able to observe its subject, uninterrupted and eclipse-free all year round.

If the mission didn’t have enough challenges, one significant one is the data that Gaia is collecting and how to get it back to Earth, where it can be made useful. The position of the satellite is tracked by a network of telescopes located around the world; this network and 450 scientists and software gurus all go to make up the Gaia Data Processing and Analysis Consortium (or DPAC to save us all time).

These unintelligibly clever men and women convert the raw data coming from Gaia into something that makes sense to the rest of us – the final product they will deliver will be the Gaia Catalogue; a chart of the position, distances and motions of over one billion stars, asteroids and planets.

So, thank you Prof. Gilmore. Your excitement for Gaia led me to work my way through the ESA web pages and stay up late watching how our will look 5 million years from now and learn what a celestial magnifying glass might be!

If you want to do the same, visit the ESA Gaia Website

Written by Alistair Maclenan, founder of Quarry One Eleven