Gaia’s scan of Milky Way comes to an end after three trillion observations - but mission continues
Gaia, the European Space Agency’s observatory that is mapping the Milky Way, has completed the sky-scanning phase of its mission - and its fuel is now nearly empty.
It has notched up more than three trillion observations of about two billion stars and other objects over the last decade, changing our understanding of our home galaxy and the cosmic neighbourhood.
“Today marks the last day of science data collection from Gaia, these observations to form part of the final data release,” said Dr Nicholas Walton, from Cambridge’s Institute of Astronomy, lead of the UK Gaia Project team and ESA Gaia Science Team member.
“Our Gaia team in the UK is now working hard on the incredibly complex data analysis for the upcoming Gaia data releases. These will enable a wealth of new discovery, adding to the science from one of the world’s most productive science discovery machines.”
Gaia was launched on 19 December 2013 and has been using about a dozen grams of cold gas per day to keep it spinning with extraordinary precision.
But it is far from the end of its mission.
Technology tests will be carried out in the coming weeks before Gaia moves to its ‘retirement’ orbit.
Two huge data releases are planned for around 2026 and the end of this decade.
“Today marks the end of science observations and we are celebrating this incredible mission that has exceeded all our expectations, lasting for almost twice its originally foreseen lifetime,” said ESA director of science Carole Mundell.
“The treasure trove of data collected by Gaia has given us unique insights into the origin and evolution of our Milky Way galaxy, and has also transformed astrophysics and Solar System science in ways that we are yet to fully appreciate. Gaia built on unique European excellence in astrometry and will leave a long-lasting legacy for future generations.”
Gaia has created the best Milky Way map yet, by charting the positions, distances, movements, brightness changes, composition and numerous other characteristics of stars, monitoring them with three instruments many times throughout the mission.
Repeated measurements of stellar distances, motions and characteristics have been key to performing ‘galactic archaeology’ on our Milky Way.
It has detected ‘ghosts’ of other galaxies, multiple streams of ancient stars that merged with the Milky Way in its early history and found evidence of the ongoing collision with the Sagittarius dwarf galaxy.
During the upcoming tests Gaia’s orientation will be changed so it will temporarily become several magnitudes brighter, making observations through small telescopes a lot easier. It will not be visible to the naked eye.
A guide to locating Gaia has been set up here and amateur astronomers are invited to share their observations.
“Gaia will treat us with this final gift as we bid farewell, shining among the stars ahead of its well-earned retirement,” said Uwe Lammers, Gaia mission manager.
“It’s a moment to celebrate this transformative mission and thank all of the teams for more than a decade of hard work operating Gaia, planning its observations, and ensuring its precious data are returned smoothly to Earth.”