A cascade of diamonds more precious than precious stones, it is light that comes from the depths of the Universe. And we haven’t seen anything yet. ESA has defined the first images of Euclid, the European space telescope that took off on July 1 from Cape Canaveral to investigate the dark part of the Universe, as “mesmerizing”, “hypnotic”. They’re just tests with minimal setup, but all those stars and galaxies dotting the dark remote sky are already a great sight. Above all, and that’s what matters, they testify that the tools work properly and excite scientists.
On the left, the entire field of view of the instrument in visible light Vis. On the right, the zoom of a small portion of the image. You see spiral and elliptical galaxies, near and far stars, star clusters, and much more. This is a raw, largely unprocessed image, it does contain some unwanted artifacts, such as cosmic ray marks. To make it, Euclid collected the light for 566 seconds (about 9 and a half minutes). – Credits: ESA/Euclid/Euclid Consortium/NASA, CC BY-SA 3.0 IG
It took just under a month for Euclid’s journey to L2, the point one and a half million kilometers from Earth from which, over the next six years, he will scrutinize the Cosmos to help us better understand the nature of dark matter and energy. Before starting to do science seriously, however, once the instruments are turned on, you need to calibrate them and make sure that everything works properly. The “commissioning” phase has therefore begun, and everything looks promising: “After more than 11 years of designing and developing Euclid, it is exciting and extremely exciting to see these first images – said Giuseppe Racca, Euclid project manager – it is even more incredible if we think we see only a few galaxies here, produced with minimal system tuning. When Euclid is fully calibrated, it will eventually observe billions of galaxies to create the largest 3D map of the sky ever seen.”
Visible and infrared light
The scientists chose three “scenes”, shots taken by the two scientific instruments (Vis, for visible light, and Nisp, the infrared spectrometer) of the space telescope. They are both details of a much larger field of view. A chessboard made up of 36 sensors, each of 16 megapixels: each shot is a mosaic of 576 million pixels. Each shot includes a patch of sky that, from Earth, we’d see just a quarter of the width and height of the full moon, yet they’re chock full of lights. There are thousands, millions, in the end there will be billions of galaxies in Euclid’s lens: from those drops of light, physicists and astrophysicists hope to decrypt the secrets of what makes the Universe move, that 95 percent of which we know almost nothing .
Launch Euclid, the detective of the dark universe – The video story
The value of Euclid will be, explains ESA, the sharpness of the images, “razor sharp”, sharp as a razor, especially those in visible light taken by the Vis instrument, to appreciate even the smallest distortions due to the presence of dark matter. In the photos disclosed today there is not yet this precision. They are “scratched” and dirtied by the traces left by cosmic rays, there is no definitive calibration and it will still take a couple of months before Euclid begins to investigate the nature of what surrounds us, yet enthusiasm is skyrocketing: ” Turning on a space instrument is a unique experience: when everything was ready, we sent the satellite the power-on command and we literally stopped breathing until, a few seconds later, we saw the first telemetry data scrolling across the screen , reporting the status of the instrument in operation. There was a lot of emotion and amidst applause and hugs, we all immediately got back to work, aware that this is only the beginning of the adventure” says Anna Di Giorgio of Inaf, who coordinates the Italian activities for the Euclid-funded mission from ASI.
Spectra of light
There was also some suspense, when turning on the instruments, even moments of “terror”, when the scientists noticed some excess light rays contaminating the images of Vis. Euclid has his back to the Sun because the Nisp instrument, an infrared spectrograph, works at very low temperatures. But evidently some fissure let some in. Once the cause was found, it was enough to reorient the telescope and, in the future, some angles will have to be avoided: an unexpected event that in the end gave “the entire team the opportunity to work in an even more cohesive and motivated way if possible. Also in these cases the professionalism of the Italian staff, both the researchers and the industrial team, has contributed decisively to keeping the situation under control and defining possible solution strategies”, commented Di Giorgio.
The launch Scientists arrived from Italy to see Euclid take off: “A piece of us flies into Space” by Matteo Marini 01 July 2023 One of the images attracts attention due to its peculiarity. It was obtained by the Nisp tool and instead of dots and galactic spirals, it is crossed by long brush strokes. It is the effect given by the “grismi”, particular prisms with which the instrument divides the light (like Newton for his experiments and Pink Floyd on the cover of The dark side of the Moon) to analyze the spectrum and thus measure the distance of each source and the speed with which it moves away from us. It will be thanks to these data that in the next six years it will be possible to create the most precise map of the Universe in three dimensions, plant new cornerstones to determine the speed of expansion of the Universe, and shed light on the great mystery of the existence of dark energy which makes it speed up.