Razor-sharp test images show Euclid’s instruments performing as expected


An early commissioning test image from Euclid’s VISible light camera – VIS – showing the full field of view on the left with a zoomed-in view of one segment’s four quadrants on the right. The zoomed-in view covers about one quarter the width and height of the full Moon. Image: ESA

The European Space Agency’s Euclid space telescope, launched 1 July atop a SpaceX Falcon 9 rocket, has reached its operational location at Lagrange Point 2, a gravitationally stable region 1.5 million kilometres (1 million miles) from Earth.

Initial test images show the spacecraft’s VISual imager (VIS) and its Near-infrared Imaging Spectrometer and Photometer (NISP) are operating in fine fashion, producing razor-sharp, wide-angle views of countless stars and galaxies. The raw images show streaks from cosmic rays, but such artefacts will be removed when science images are processed.

“After more than 11 years of designing and developing Euclid, it’s exhilarating and enormously emotional to see these first images,” said 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 Near-Infrared Spectrometer and Photometer – NISP – is designed to measure the amount of light emitted by galaxies at different IR wavelengths. The left image shows NISP’s full field of view while the right-side image shows a zoomed-in look. Image: ESA

Said Yannick Mellier, lead of the multi-agency Euclid research consortium: “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.”

The $1.5 billion Euclid is a first-of-a-kind attempt to pin down the nature of dark matter, the unknown material pervading the cosmos, and dark energy, the mysterious repulsive force that is speeding up the expansion of the universe.

By studying subtle changes in the light from galaxies over the past 10 billion years, Euclid’s cameras will help scientists find out if dark energy is consistent with an unchanging “cosmological constant” once predicted by Einstein’s theory of general relativity or whether the current understanding of gravity needs revision.

Euclid also will study the nature of dark matter by analysing the shapes of some 1.5 billion galaxies to determine how they have been distorted by clouds of unseen dark matter filling the space between Euclid and its targets.

“It is fantastic to see the latest addition to ESA’s fleet of science missions already performing so well,” said ESA Director General Josef Aschbacher. “I have full confidence that the team behind the mission will succeed in using Euclid to reveal so much about the 95 percent of the Universe that we currently know so little about.”