Enlarge / One of the first galaxies that Euclid observed is nicknamed the "Hidden Galaxy." This galaxy, also known as IC 342 or Caldwell 5, is difficult to observe because it lies behind the busy disk of our Milky Way. (credit: ESA/Euclid/Euclid Consortium/NASA, image processing by J.-C. Cuillandre (CEA Paris-Saclay), G. Anselmi )

The European Space Agency released the first five science images from the Euclid space telescope Tuesday, showing how the wide-angle observatory will survey familiar cosmic wonders like galaxies and stars to study the unseen dark energy and dark matter that dominate the Universe.

Stationed nearly a million miles (1.5 million kilometers) from Earth, Euclid will scan one-third of the sky over the next six years, collecting an estimated 1 million images of billions of galaxies. Scientists have developed sophisticated algorithms to analyze the data coming down from Euclid to measure the distances and shapes of each of these galaxies.

From that, scientists can infer how the influence of dark matter pulls on the galaxies, forming clusters and causing them to spin faster. Dark energy is the mysterious force that is driving the accelerated expansion of the Universe.

Enlarge / Euclid’s Visible instrument (VIS) will image the sky in visible light (550–900 nm) to take sharp images of billions of galaxies and measure their shapes. This image was taken during the commissioning of Euclid. (credit: ESA/Euclid/Euclid Consortium/NASA)

Nearly one month after launching into space , a European telescope has begun taking its first images and data of the Universe. And to the delight of scientists at the European Space Agency, everything seems to be working rather well.

As part of the months-long commissioning phase, both the telescope's visual and infrared-light cameras have started snapping photos of the cosmos. Scientists who helped develop these cameras—VIS for visible light, and NISP for Near Infrared Spectrograph and Photometer—say the new instruments work superbly.

"We are very pleased that the commissioning phase of Euclid is progressing well," Alessandra Roy, Euclid project manager at the German Space Agency at DLR, said . "The spacecraft will soon reach its final position at a distance of 1.5 million kilometers from Earth and begin scientific observations."

Enlarge / SpaceX's Falcon 9 rocket soars through the sky over Cape Canaveral with Europe's Euclid space telescope. (credit: Stephen Clark/Ars Technica)

A European Space Agency telescope launched Saturday on top of a SpaceX Falcon 9 rocket from Florida to begin a $1.5 billion mission seeking to answer fundamental questions about the unseen forces driving the expansion of the Universe. The Euclid telescope, named for the ancient Greek mathematician, will observe billions of galaxies during its six-year survey of the sky, measuring their shapes and positions going back 10 billion years, more than 70 percent of cosmic history.

Led by the European Space Agency, the Euclid mission has the ambitious goal of helping astronomers and cosmologists learn about the properties and influence of dark matter and dark energy , which are thought to make up about 95 percent of the Universe. The rest of the cosmos is made of regular atoms and molecules that we can see and touch.

Stumbling in the dark

“To highlight the challenge we face, I would like to give the analogy: It’s very difficult to find a black cat in a dark room, especially if there’s no cat,” said Henk Hoekstra, a professor and cosmologist at Leiden Observatory in the Netherlands. “That’s a little bit of the situation we find ourselves in because we have these observations … But we lack a good theory. So far, nobody has come up with a good explanation for dark matter or dark energy.”

Enlarge / The Euclid mission is ready to go—all it needs is a launch vehicle. (credit: Thales Alenia Space )

The author of this piece is part of the team that has helped developed the Euclid mission.

The European Space Agency had been on the verge of launching the billion-euro Euclid satellite , which is designed to address the most pressing unsolved questions in astronomy: What are the true natures of dark matter and energy? ESA had scheduled a March 2023 launch for Euclid from French Guiana—but it was on a Soyuz rocket. The war in Ukraine brought an end to Soyuz operations from Guiana and started a period of uncertainty for Euclid’s team.

Keeping Euclid in storage could cost 100 million euros per year and put its entire scientific team and infrastructure in standby mode, potentially compromising European leadership in space-based observational cosmology. The partner ESA has used for almost all its launches, Arianespace, is building what should be a good backup launcher, the Ariane 62. But that rocket has not flown yet, and with each passing month, its test flight date slips further. Once it’s ready, Euclid would not even be the first Ariane 62 launch: at least four other satellites are in the queue before it.