Barely a month since its takeoff… But the Euclid telescope is already at his post 1.5 million kilometers from Earth! European teams have captured the first pictures of its two instruments. With a sigh of satisfaction: so far everything is working exactly as expected!
The real scientific campaign will begin in a few months.
Terminus, everyone get off at L2!
Since taking off on July 1, the European Euclid telescope has traveled a lot. Its launch brought it on the right trajectory so that in four weeks it reached the Lagrange point L2, located 1.5 million kilometers from Earth (yes, the same area it shares with the James Webb, or the Gaia telescope). Euclid arrived on site on July 28, and he maneuvered to begin his long series of ellipses. Remember that if we say a Lagrange point, it is in fact a particular area, within which the influence of solar attraction and that of the Earth are equivalent, it is therefore possible to remain on the spot and “to orbit around nothing”.
As soon as it arrived, its instruments properly cooled, the scientific teams began to work with the two VIS and NISP instruments. Together, these two will make it possible to map hundreds of millions, and even possibly billions, of galaxies in visible and infrared light so that ground teams, after analysis, can better understand the structure of the Universe, and the mysteries dark matter and dark energy.
Promising first shots
On the two “first images” from Euclid’s instruments and published by ESA on July 31, we mainly see… stars! And not only are there few galaxies, but in addition, there are artefacts even though the photographs are very precise.
Would there be a problem? No, don’t worry. First, the NISP image was captured in just 100 seconds of exposure, nearly a fifth of what will be used to detect galaxies. Then and above all, these images are so to speak raw, they have not been processed! Groups of stars, clouds of gas, all of this will disappear from the “useful” readings that astrophysicists will use to map galaxies. As for the luminous lines on the VIS images, they are essentially due to high-energy particles which strike the enormous CCD sensor of the instrument. They too are removed in post-processing!
The lights of the past…
In reality, the first comments from the teams (a significant part of which are French) are particularly encouraging. The two sensors are in line with what was expected, and their performance would even be slightly better than during the simulations! However, during the very first readings sent by Euclid, several researchers had cold sweats: certain orientations of the telescope produce on the VIS sensor a particularly handicapping solar reflection! The orientation adjustments (which will not impact the mission) were able to fix the problem very quickly.
The pictures already show elliptical galaxies, others in spirals… As they are calibrated, the two instruments will work together to start delivering ever more precise readings, with the start of the official scientific campaign of six years, which will begin in October. And the first publications with Euclid measurements are already expected for the winter.
Source : ESA
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