After fears that Europe's space scope was toast, its first images look mighty fine

Here's looking at Euclid

Astronomers are breathing a sigh of relief that the 600-megapixel Euclid wide-angle space telescope's instruments appear to be working well, despite discovering a gap in the orbiter's hull that allowed sunlight to leak through and contaminate some images.

Launched a month ago, Euclid will snap billions of galaxies to help astronomers piece together the largest three-dimensional map of the universe. The telescope hasn't yet started its official observations – studying the impacts of dark matter and dark energy – but the European Space Agency has successfully tested the spacecraft's instruments.

The latest images, captured by its VISible instrument (VIS) and Near-Infrared Spectrometer and Photometer (NISP), show the shapes of faraway galaxies covering a small region of the sky. They prove that Euclid is working well, according to Carole Mundell, ESA's director of science.

"Our teams have worked tirelessly since the launch of Euclid on July 1 and these first engineering images give a tantalising glimpse of the remarkable data we can expect from Euclid," she declared in a statement. 

Getting over the dazzle problem

The space agency wasn't always so confident about the observatory's abilities – especially after it found an odd light pattern affecting some of its images.

The issue was later found to be from sunlight streaming into the spacecraft through a tiny gap. The issue only appeared when Euclid was at specific angles to the Sun and scientists realized they could snap clear images by avoiding orienting the telescope in certain directions that allowed sunlight to shine through its cracks. 

"After more than 11 years of designing and developing Euclid, it's exhilarating and enormously emotional to see these first images," enthused Euclid project manager Giuseppe Racca.

"It's even more incredible when we think that we see just a few galaxies here, produced with minimum system tuning. The fully calibrated Euclid will ultimately observe billions of galaxies to create the biggest ever 3D map of the sky."

Euclid's VIS instrument snaps detailed images of distant galaxies at visible wavelengths to capture their individual shapes. Astronomers can study each object more carefully by analyzing infrared data from its NISP device, which splits light from each galaxy and star to calculate its distance from Earth. 

Astroboffins using the scope will then use this information to build a 3D map of the universe dating back to ten billion years and covering over a third of the sky. Scientists hope that effort will reveal secrets of how dark matter and dark energy work. Little is known about these two mysterious components, but scientists estimate that they make up 95 percent of the universe and drive its expansion.

"We don't know what dark energy is," Mike Seiffert, a project scientist working at NASA's Jet Propulsion Laboratory who contributed to the Euclid mission, previously told The Register.

"We know so little about it because its effect on Earth – or the Solar System, or of our own galaxy – is extremely small. It is only by looking at the largest scales in the universe that we can detect it at all."

Scientists will examine the distribution of matter in the universe and how it behaves across different distances. Across shorter distances, gravity is attractive and brings matter together – but at longer distances, dark energy takes over and drives matter further apart. 

Yannick Mellier, an astronomer at the Institut d'Astrophysique de Paris – part of the Euclid Consortium backing the project – declared "The outstanding first images obtained using Euclid's visible and near-infrared instruments open a new era to observational cosmology and statistical astronomy. They mark the beginning of the quest for the very nature of dark energy, to be undertaken by the Euclid Consortium." ®

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