On Thursday 27 March, the European Area Company (ESA) despatched its final messages to the Gaia Spacecraft. They advised Gaia to close down its communication programs and central pc and mentioned goodbye to this superb house telescope.
Gaia has been essentially the most profitable ESA house mission ever, so why did they flip Gaia off? What did Gaia obtain? And maybe most significantly, why was it my favorite house telescope?
Artist’s impression of the Gaia spacecraft in entrance of the Milky Manner.
ESA/ATG medialab; background: ESO/S. Brunier
Working on empty
Gaia was retired for a easy cause: after greater than 11 years in house, it ran out of the chilly fuel propellant it wanted to maintain scanning the sky.
The telescope did its final statement on 15 January 2025. The ESA crew then carried out testing for just a few weeks, earlier than telling Gaia to depart its dwelling at a degree in house referred to as L2 and begin orbiting the Solar away from Earth.
L2 is one among 5 “Lagrangian points” round Earth and the Solar the place gravitational situations make for a pleasant, steady orbit. L2 is positioned 1.5 million kilometres from Earth on the “dark side”, reverse the Solar.
The Lagrange factors round Earth and the Solar, together with L2.
NASA, STScI, CSA
L2 is a extremely prized location as a result of it’s a steady spot to orbit, it’s shut sufficient to Earth for simple communication, and spacecraft can use the Solar behind them for solar energy whereas wanting away from the Solar out into house.
It’s additionally too distant from Earth to ship anybody on a restore mission, so as soon as your spacecraft will get there it’s by itself.
Conserving L2 clear
L2 at present hosts the James Webb Area Telescope (operated by the USA, Europe and Canada), the European Euclid mission, the Chinese language Chang’e 6 orbiter and the joint Russian-German Spektr-RG observatory. Since L2 is such a key location for house missions, it’s important to maintain it away from particles and retired spacecraft.
A ultimate standing replace from Gaia.
ESA, CC BY-SA
Gaia used its thrusters for the final time to push itself away from L2, and is now drifting across the Solar in a “retirement orbit” the place it gained’t get in anyone’s means.
As a part of the retirement course of, the Gaia crew wrote farewell messages into the craft’s software program and despatched it the names of round 1,500 individuals who labored on Gaia over time.
What’s Gaia?
Gaia seems to be a bit like a spinning prime hat in house. Its principal mission was to provide an in depth, three-dimensional map of our galaxy, the Milky Manner.
To do that, it measured the exact positions and motions of 1.46 billion objects in house. Gaia additionally measured brightnesses and variability and people information had been used to supply temperatures, gravitational parameters, stellar varieties and extra for thousands and thousands of stars. One of many key items of knowledge Gaia supplied was the space to thousands and thousands of stars.
A diagram displaying how telescopes like Gaia measure the parallax angle. With a little bit of trigonometry we will use the space from Earth to the Solar and the parallax angle to measure the space to the star.
ESA/ATG medialab
A cosmic measuring tape
I’m a radio astronomer, which suggests I exploit radio telescopes right here on Earth to discover the Universe. Radio gentle is the longest wavelength of sunshine, invisible to human eyes, and I exploit it to analyze magnetic stars.
However despite the fact that I’m a radio astronomer and Gaia was an optical telescope, wanting on the similar wavelengths of sunshine our eyes can see, I exploit Gaia information nearly each single day.
I used it right this moment to learn how distant, how shiny, and how briskly a star was. Earlier than Gaia, I’d most likely by no means have recognized how distant that star was.
That is important for determining how shiny the celebrities I research actually are, which helps me perceive the physics of what’s taking place in and round them.
A map displaying the positions and radio luminosity of the celebrities (the colored factors) from my work on radio stars. The positions and distances of 95% of the celebrities proven right here got here from Gaia information.
Laura Driessen
An enormous success
Gaia has contributed to hundreds of articles in astronomy journals. Papers launched by the Gaia collaboration have been cited properly over 20,000 occasions in complete.
Gaia has produced too many science outcomes to share right here. To take only one instance, Gaia improved our understanding of the construction of our personal galaxy by displaying that it has a number of spiral arms which might be much less sharply outlined than we beforehand thought.
Artist’s impression of our Milky Manner Galaxy, wanting down from above. That is the most recent map of our Galaxy utilizing information from the Gaia mission. The spiral arms arms are much less distinguished than beforehand thought.
ESA/Gaia/DPAC, Stefan Payne-Wardenaar
Probably not the top for Gaia
It’s troublesome to specific how revolutionary Gaia has been for astronomy, however we will let the numbers communicate for themselves. Round 5 astronomy journal articles are printed day-after-day that use Gaia information, making Gaia essentially the most profitable ESA mission ever. And that gained’t come to a whole cease when Gaia retires.
The Gaia collaboration has printed three information releases up to now. That is the place the collaboration performs the processing and checks on the info, provides some essential evaluation and releases all of that in a single huge hit.
And by chance, there are two extra huge information releases with much more data to return. The fourth information launch is anticipated in mid to late 2026. The fifth and ultimate information launch, containing the entire Gaia information from the entire mission, will come out someday within the 2030s.
This text is my very own small tribute to a telescope that modified astronomy as we all know it. So I’ll finish by saying an enormous thanks to everybody who has ever labored on this superb house mission, whether or not it was engineering and operations, turning the info into the superb useful resource it’s, or any of the opposite many roles that make a mission profitable. And thanks to those that proceed to work on the info as we communicate.
Lastly, thanks to my favorite house telescope. Goodbye, Gaia, I’ll miss you.
