The European Space Agency’s Gaia observatory has created the most accurate map of the Milky Way. The position and motion of nearly 2 billion stars is used to better understand our galaxy’s present and past. But the teams are now looking to the future. One of them has set its sights on a follow-up mission that can re-observe what Gaia saw and go into the infrared to see where Gaia couldn’t.
Gaia’s incredible work continues – thanks to Gaia, for example, we know that the Milky Way absorbed several smaller galaxies many billions of years ago – but over time the map becomes less accurate. In a few decades it will no longer be good enough for the kind of work astronomers are used to doing with the spacecraft.
GaiaNIR (NIR stands for near infrared) will allow the observatory to see through the dust in the plane of the Milky Way. This will provide a better understanding of the dynamic processes at the core, in regions of strong star formation, and increase the measured number of stars by a factor of six or even ten.
“Although Gaia is very brilliant and revolutionising everything, it actually only measures 1 per cent of the galaxy,” Professor David Hobbs of Lund University, who proposed GaiaNIR, told IFLScience. “The important thing about infrared, of course, is that all the really dynamically interesting parts of the galaxy are all in the galactic plane, and that’s where all the dust is. Gaia is very good at seeing out of the galaxy, but actually not so good at seeing into the galaxy. It needs glasses, in a way, to see through the dust, and that’s what the near-infrared detectors will enable.”
Not to be everything Annie, get your gun about it, but the proposal is for GaiaNIR to do everything Gaia can, only better. We will not throw away the incredible work that Gaia has done – in fact, a new mission building on it is expected to increase the precision by a factor of 15. Such precision has long been sought in astrometry, but it has remained out of reach due to many challenges.
The team also hopes to incorporate new instruments, such as a spectrograph, to gain even more insight into the stars and other objects that GaiaNIR will measure. Gaia has not only allowed scientists to measure the position of stars and distant galaxies, but also to discover black holes, asteroids and asteroid moons. It is vital to continue measuring many of these systems because their motion changes in ways we cannot predict.
“If you don’t keep measuring them, in 20 years they won’t be where you think they’ll be,” Professor Hobbs continued. “The problem with this kind of mission is that it’s very hard to summarise how many interesting things there are because there are so many of them. I mean, I could list one case after another, but there are just so many different cases.”
Given the limitless potential for discovery, the mission proposals for GaiaNIR hope that such a mission will be taken up. If selected, it will be launched in the 2040s, building on the still-growing legacy of its predecessor.
Professor Hobbs presented details of the proposal at the XXXII General Assembly of the International Astronomical Union in Cape Town.
