2023-11-07 15:15:10
One of the first color images of the cosmos taken by the Euclid satellite, showing the spiral galaxy IC 342. EUROPEAN SPACE AGENCY
The Perseus galaxy cluster, the famous Horsehead Nebula in the constellation Orion, the beautiful spiral galaxy IC 342, the irregular galaxy NGC 6822 and a globular star cluster located in the Milky Way at 7800 light years from Earth. These are the subjects of the first five color photographs taken by the Euclid satellite of the European Space Agency (ESA) and unveiled on Tuesday November 7. Not five close-up portraits, but rather five landscapes, because Euclid’s main characteristic is to take wide-field images, unlike the Hubble or James-Webb space telescopes, which focus their gaze on tiny portions of the sky.
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Departing on July 1 from Cape Canaveral (Florida), the cosmology satellite, whose mission will consist of tracking dark matter and dark energy – two mysterious entities which make up 95% of the content of the Universe – is still not not entered the operational phase. It initially took a month to reach its final destination, Lagrange point number 2, a very stable area of space 1.5 million kilometers from Earth, on the side opposite the Sun, where is also located the James Webb. Then began checking the proper functioning of the device and its instruments, with its hazards and reliefs.
In the cold sweat category, the ESA had the displeasure to note that, at times, Euclid’s fine guidance system, disrupted by protons coming from the Sun, lost its guide stars, which destabilized the device and gave images where the stars seemed to make loops. To get everything back to normal, we had to write a patch and upload it to the satellite.
Extreme image quality
Another area of concern for researchers, the phenomenon of ice deposition. As Francis Bernardeau, astrophysicist at the CEA and deputy head of the Euclid scientific consortium, which brings together more than 250 laboratories around the world, explains, “the water contained in the satellite materials evaporates and recondenses on the instruments. This is a problem encountered by all space imagers, which is very difficult to evaluate and model. But, in this case, with Euclid, we are better than we thought.”
One of the first color images of the cosmos taken by the Euclid satellite, showing the Perseus galaxy cluster. EUROPEAN SPACE AGENCY
The researchers and engineers who operate the satellite remotely are now in the phase of evaluating the instruments’ performances. A crucial point because Euclid, to study the distribution of dark matter and establish the largest three-dimensional map of the Universe, aims for extreme image quality. The bet seems won, believes, without any triumphalism, Francis Bernardeau: “As for the sharpness of the images, we are completely at the level of expectations. The key will be to maintain these qualities during the six years of the mission. » However, we note, on the photos revealed on November 7, the presence of strange bluish spots. “These are ghost images that come from the inevitable imperfections of the optical system, explains the CEA researcher, but, once everything is calibrated, we will know how to clean them. »
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