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The spacecraft’s two instruments took the preliminary test images, revealing scintillating starry views that prove everything onboard is in tip-top shape.
“After more than 11 years of designing and developing Euclid, it’s exhilarating and enormously emotional to see these first images,” said Giuseppe Racca, Euclid project manager at the European Space Agency, in a statement.
“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, the European Space Agency’s newest observatory, has spent the past month since its July 1 launch traveling to its orbital point, located 1 million miles (1.5 million kilometers) away from Earth.
The 4-foot-diameter (1.2-meter-diameter) telescope will remain at what’s known as the sun-Earth Langrangian point L2, also home to NASA’s James Webb Space Telescope, a partnership with ESA and the Canadian Space Agency. Euclid will keep pace with Earth as our planet orbits the sun.
Scientists are already encouraged by the capabilities showcased by Euclid’s initial images, which demonstrate that the telescope may exceed expectations.
“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, in a statement. “I have full confidence that the team behind the mission will succeed in using Euclid to reveal so much about the 95% of the Universe that we currently know so little about.”
Wide-field and infrared cameras
Euclid will spend the next two months testing and calibrating its instruments — a visible-light camera and a near-infrared camera/spectrometer — before surveying about one-third of the sky for the next six years.
The telescope’s visible instrument, or VIS, will take images of billions of galaxies, something hinted at in one of the initial test images. Euclid’s wide perspective can record data from a part of the sky more than 100 times bigger than what Webb’s camera can capture. The telescope’s image quality will be at least four times sharper than those of ground-based sky surveys.
“Ground-based tests do not give you images of galaxies or stellar clusters, but here they all are in this one field,” said Reiko Nakajima, Euclid VIS instrument scientist, in a statement. “It is beautiful to look at, and a joy to do so with the people we’ve worked together with for so long.”
When the VIS instrument switched on for the first time, the team was shocked to see an unexpected light pattern in the images, which was determined to be sunlight creeping in through a tiny gap. As long as Euclid remains oriented in a specific way, VIS won’t encounter any light contamination in its images.
Meanwhile, the Near-Infrared Spectrometer and Photometer instrument, or NISP, will capture images of galaxies in infrared light and measurements that map the distance of each galaxy.
“Each new image we uncover leaves me utterly amazed. And I admit that I enjoy listening to the expressions of awe from others in the room when they look at this data,” said William Gillard, Euclid NISP instrument scientist, in a statement.
Investigating invisible dark matter
Euclid’s primary goal is to observe the cosmic mysteries of the universe, including dark matter and dark energy.
While dark matter has never actually been detected, it is believed to make up at least 85% of the total matter in the universe. Meanwhile, dark energy is a mysterious force thought to play a role in the accelerating expansion of the universe.
In the 1920s, astronomers Georges Lemaître and Edwin Hubble discovered that the universe has been expanding since its birth 13.8 billion years ago. But research that began in the 1990s has shown that something sparked an acceleration of the universe’s expansion about 6 billion years ago, and the cause remains a mystery.
Unlocking the true nature of dark energy and dark matter could help astronomers understand what the universe is made of, how its expansion has changed over time, and whether there is more to understanding gravity than meets the eye. Both dark matter and dark energy also play a role in the distribution and movement of objects, such as galaxies and stars, across the cosmos.
Euclid is designed to create the largest and most accurate three-dimensional map of the universe. The mission will observe billions of galaxies that stretch 10 billion light-years away to reveal how matter may have been stretched and pulled apart by dark energy over time. These observations will effectively allow Euclid to see how the universe has evolved over the past 10 billion years.
The telescope was named in honor of Euclid of Alexandria, the Greek mathematician who lived around 300 BC and is considered the father of geometry.
As Euclid makes its observations, the telescope will create a catalog of about 1.5 billion galaxies and the stars within them. The observatory will capture a treasure trove of data for astronomers that includes each galaxy’s shape, mass and number of stars created per year. Euclid’s ability to see in near-infrared light, similar to Webb, could also reveal previously unseen objects in our own Milky Way galaxy, such as brown dwarfs and ultra-cool stars.
