2023-07-31 12:59:44
Launched into space from Cape Canaveral on July 1, Euclid, the space telescope of the European Space Agency (ESA), has arrived safely at Lagrange 2 point. It has already sent promising technical images to show that it works and that its calibration is in very good progress. Here is what he saw.
“After more than eleven years of designing and developing Euclid, it is exhilarating and extremely moving to see these first images,” enthuses Giuseppe Racca, Euclid project manager, in the publication of the ESA. “It’s even more amazing when you consider that we only see a few galaxies here, produced with minimal system tuning. Euclid, when fully calibrated, will eventually observe billions of galaxies to create the largest 3D map of the sky never realized”, he adds.
The first image is the vision of a single detector: it shows stars, star clusters and galaxies. All stars exhibit six peaks due to diffraction effects in the telescope; they are mostly visible here for the brighter stars.
>> The image taken by the VIS instrument (see below for a zoomed view of the sensor circled in red):
Full field of view of Euclid’s VIS instrument. Early commissioning test image released on July 31, 2023. [ESA]
Among the myriad of fainter objects, many, if not most, are distant, faint galaxies: quite small, they look like stars. It is these galaxies whose shapes will be measured to provide much of the information on dark matter and dark energy.
>> The image from one of the VIS instrument’s 36 sensors shows stars and galaxies, with multiple proton tracks coming from the solar winds:
Detail of the field of view of the Euclid VIS instrument. Early commissioning test image released on July 31, 2023. [ESA]
Streams of particles – mostly protons sent out from the Sun – are seen reaching the detectors after traveling through space, as well as three donut-shaped “ghosts” caused by reflections in Euclid’s optical system. These appearances are quite normal and astronomers know how to electronically clean the images in order to then obtain an optimal science.
The stars in the cluster (in the upper right square) were born from the same cloud of gas and dust and are still relatively young. The image contains several large galaxies, notably at the bottom right, but also other galaxies at the edge of the image in the other quarters of the detector.
The second image shows the position of the detector shown in the image above in the full mosaic of 36 detectors. With all detectors exposed simultaneously, each VIS image weighs 1.2 Gigabytes, requiring over 300 HDTVs to display it in full detail.
The image is presented in its raw state, without any processing – only the logarithmic gray scale of the display has been defined. The exposure time is 566 seconds, or just under ten minutes; the sheer number of tiny stars and galaxies indicates that the VIS instrument achieves the required high level of sensitivity. Star image profiles indicate that the Euclid telescope is in focus.
A trip of almost four weeks
ESA’s telescope journey will have lasted just under a month (read box): it has arrived at its operational orbit, the Lagrange 2 (L2) point, the region where the James Webb Space Telescope is already located (JWST), as well as the mission Gaiaof ESA, which scans our Milky Way.
>> Read: The Euclid satellite to conquer the dark side of the Universe
This place in space is an invisible point of balance of forces, infinitesimal in size, located about 1.5 million kilometers from us, or some four times the Earth-Moon distance. An ideal area to place observation satellites in orbit, because their vision is not disturbed by the presence of the Sun, the Earth and the Moon: the vessels can keep them on their backs at all times by deciphering the cosmos distant.
>> The trajectories of Euclid (in green), JWST (in blue) and Gaia (in yellow) at point L2. On the animation, their orbits seem to intersect, but they don’t, space is vast around L2:
ACCEPT MORE INFO
Euclid’s transit time went smoothly and was used to commission the satellite, this is called commissioning. The team ofESOC, ESA’s Space Operations Center in Darmstadt, Germany, checked its functionality: communications, power, pointing and telescope focus. For the time being, everything confirms that it will be able to carry out the scientific mission for which it was designed. (read box)or even achieve other wonders.
VIS and NISP, its two precious instruments, have also been checked: the first sees in visible light and captures its images in orange and red light, and the second, a spectrometer and photometer, observes in the near infrared.
The VIS instrument, with its 36 CCD sensors, is the blue square in the middle, bottom of the image. This is one of the biggest “cameras” in space. NISP, the spectrometer and photometer is on the left, almost completely covered with sheets of multi-layered insulation. [Airbus Defence and Space – Toulouse – ESA]
The VIS and NISP instruments
The VIS engineering image already shows thousands of stars and galaxies; it is considered a technical document, to prove that everything works and to calibrate the instrument.
“I am very relieved! The teams – from Thales, Airburs, VIS, NISP and ESA – gathered in Darmstadt have worked a lot: the entire commissioning phase is almost complete”, said Stéphane Paltani by telephone to RTSinfo. The professor from the University of Geneva and his team were involved in the design and manufacture of the VIS instrument, as were other institutes in Italy, France and the United Kingdom, as well as the Swiss company APCO; le Mullard Space Science Laboratory (MSSL) is the main contractor. “The scientific images will arrive in August”, specifies the cosmologist: “In November, we will make them public, with the first scientific results”.
VIS has 36 CCD detectors, each divided into four quarters. “To avoid the black bands that criss-cross his vision, he will take the same images four times, shifting Euclid slightly each time: a technique that allows the shots to be superimposed and thus recompose an image that can be used by the scientific community”, explains Stéphane Paltani. . VIS will measure and map the distribution of galaxies in the Universe, as well as the evolution of this distribution over time.
>> Read also: Does time warp like space? A big question about to be answered
As for the NISP spectro-imager, it works in the near infrared. Its role is to quantify the light emitted by galaxies at different wavelengths. This measurement will allow astronomers in particular to determine the distance at which each galaxy is located.
>> A spectroscopic image of NISP:
An image taken by NISP: the light passed through a “grism” before reaching the detector. This device divides the light from each star and galaxy by wavelength, so each vertical line of light in the image is a star or galaxy. This particular way of looking at the Universe makes it possible to distinguish characteristic signatures in the galaxies, which make it possible to evaluate their distances from the Earth. [ESA]
By combining the information on the distance with that on the shape of the galaxies measured by VIS, it will be possible to draw up a map of the distribution of galaxies in the Universe and of the evolution of this distribution over time. This will not be done with spectroscopy, because an insufficient number of galaxies are visible with this technique, but with the “imaging” mode of the instruments.
This 3D map will provide information on dark matter – at the origin of gravity – and on dark energy – at the origin of the accelerated expansion of the Universe. These two entities are called “black” (or “dark”) because they do not interact with light and, moreover, because scientists have not yet succeeded in identifying their mysterious nature.
>> NISP takes mid-infrared images:
A mid-infrared view of Euclid’s NISP instrument. Early commissioning test image released on July 31, 2023. [ESA]
News dealt with in the 3:00 p.m. hourly newspaper
Stephanie Jaquet
1690809593
#Euclid #satellite #arrived #safely #working #perfectly #rts.ch