Artist’s impression of the Gaia spacecraft in entrance of the Milky Method. (credit score: ESA/ATG medialab; background: ESO/S. Brunier) |
by Laura Nicole Driessen
Monday, April 7, 2025
On Thursday 27 March, the European Area Company (ESA) despatched its final messages to the Gaia spacecraft. They instructed Gaia to shut down its communication systems and central computer and stated goodbye to this superb area telescope.
Gaia has been probably the most profitable ESA area mission ever, so why did they flip Gaia off? What did Gaia obtain? And maybe most significantly, why was it my favourite area telescope?
Operating on empty
Gaia was retired for a easy motive: after greater than 11 years in area, it ran out of the cold gas propellant it wanted to maintain scanning the sky.
| Gaia’s fundamental mission was to supply an in depth, three-dimensional map of our galaxy, the Milky Method. |
The telescope did its final commentary on January 15, 2025. The ESA crew then carried out testing for just a few weeks, earlier than telling Gaia to depart its house at a point in space called L2 and begin orbiting the Solar away from Earth.
L2 is considered one of 5 Lagrangian factors round Earth and the Solar the place gravitational circumstances make for a pleasant, steady orbit. L2 is positioned 1.5 million kilometers from Earth on the “darkish facet”, reverse the Solar.
L2 is a highly 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 trying away from the Solar out into area.
It’s additionally too far-off from Earth to ship anybody on a restore mission, so as soon as your spacecraft will get there it’s by itself.
Retaining L2 clear
L2 at the moment hosts the James Webb Space 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 area missions, it’s important to maintain it away from particles and retired spacecraft.
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 received’t get in anyone’s method.
As a part of the retirement course of, the Gaia crew wrote farewell messages into the craft’s software and despatched it the names of round 1,500 individuals who labored on Gaia over time.
What’s Gaia?
Gaia appears a bit like a spinning high hat in area. Its fundamental mission was to supply a detailed, three-dimensional map of our galaxy, the Milky Way.
To do that, it measured the exact positions and motions of 1.46 billion objects in space. Gaia additionally measured brightnesses and variability and people knowledge have been used to supply temperatures, gravitational parameters, stellar sorts and extra for hundreds of thousands of stars. One of many key items of knowledge Gaia offered was the space to hundreds of thousands of stars.
A cosmic measuring tape
I’m a radio astronomer, which implies I exploit radio telescopes right here on Earth to discover the Universe. Radio mild is the longest wavelength of sunshine, invisible to human eyes, and I exploit it to research magnetic stars.
However though I’m a radio astronomer and Gaia was an optical telescope, trying on the identical wavelengths of sunshine our eyes can see, I exploit Gaia knowledge virtually each single day.
I used it right now to learn the way far-off, how brilliant, and how briskly a star was. Earlier than Gaia, I’d most likely by no means have recognized how far-off that star was.
That is important for determining how brilliant the stars I study actually are, which helps me perceive the physics of what’s occurring in and round them.
An enormous success
Gaia has contributed to 1000’s of articles in astronomy journals. Papers launched by the Gaia collaboration have been cited more than 20,000 times in total.
| 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 on daily basis that use Gaia knowledge. |
Gaia has produced too many science outcomes to share right here. To take only one instance, Gaia improved our understanding of the structure of our own galaxy by exhibiting that it has a number of spiral arms which can be much less sharply outlined than we beforehand thought.
Probably not the tip 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 on daily basis that use Gaia knowledge, making Gaia the most successful ESA mission ever. And that received’t come to an entire cease when Gaia retires.
The Gaia collaboration has printed three knowledge releases thus far. That is the place the collaboration performs the processing and checks on the info, provides some necessary evaluation and releases all of that in a single large hit.
And fortunately, there are two more big data releases with much more data to come back. The fourth knowledge launch is predicted in mid to late 2026. The fifth and closing knowledge launch, containing the entire Gaia knowledge 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 area 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 favourite area telescope. Goodbye, Gaia, I’ll miss you.
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