The European Space Agency‘s (ESA) Euclid space telescope is set to release its first data, a preview of expansive deep-field space observations that will one day yield a 3D map of the universe’s dark matter.
Launched from Cape Canaveral, Florida, in July 2023 with assistance from NASA, Euclid has been observing the cosmos since February 2024. A consortium of over 2000 scientists from 300 institutions around the globe worked on developing Euclid’s instruments and data analysis.
Euclid consists of a Thales Alenia Space satellite carrying an Airbus Defense and Space payload of scientific instrumentation, which helps it produce an enormous amount of deep field data. Across three mosaics, Euclid observes galaxy clusters, galactic nuclei, and various transient phenomena. The telescope’s single-shot field of view is 240 times that of the Hubble Telescope, capturing visible and infrared light.
Over the next six years, Scientists expect the 100 GB of data sent back daily from Euclid to show 1.5 billion galaxies. The enormity of the data stream presents both opportunities and challenges for researchers. The Euclid consortium is currently handling the load across a network of nine data centers. Scientists employing machine learning algorithms, volunteer researchers, and others comb through the ongoing data stream, seeking answers to how supermassive black holes grow, how spiral arms form, and other fundamental questions.
“Approximately 100 GB of raw data is processed virtually in real-time every day. The demands on photometric precision are enormous and require a completely new approach to the methods used to calibrate the data,” said Max Fabricius, who leads the German Science Data Center (SDC-DE) at the Max Planck Institute for Extraterrestrial Physics (MPE), a part of the network responsible for 10% of the processing.
Initial Data Release
This release serves as a “quick” preview, offering a glimpse of the significant data drops to come. It covers 2,000 square degrees—14% of the total survey area—including approximately 63 square degrees of deep-field observations. The first full cosmology data release, scheduled for October 2026, will include multiple deep-field passes.
The initial dataset contains a catalog of 380,000 galaxies, described in detail, including features like spiral arms and tidal tails. However, this accounts for only 0.4% of the expected final total. By the project’s conclusion, Euclid is expected to record detailed morphology for at least ten times as many galaxies as any previous survey.
Observing Dark Matter
One of Euclid’s primary missions is to map the universe’s dark matter. As light travels toward Earth from distant galaxies, matter and dark matter along its path bend and distort the wavelength. By observing this “gravitational lensing,” scientists aim to determine how dark matter is distributed. Extreme distortions create “strong lensing,” and the newly released data includes 500 potential strong lensing candidates.
“AI systems will ultimately be essential for analyzing the 200 times larger sky area at the end of the mission. The number of galaxies distorted by lensing will eventually increase to a staggering 100,000, about 100 times more than currently known. Human classification of individual objects will not be possible for this unprecedented dataset,” said Knud Jahnke of the Max Planck Institute for Astronomy (MPIA).
Euclid’s precise measurement capabilities will also detect weak lensing, though these subtle distortions will only become evident through statistical analysis of a more complete dataset. Once fully cataloged, these distortions will enable Euclid to create 3D maps of dark matter distribution across the universe.
Additional Missions
Scientists at the Max Planck Institute for Astronomy (MPIA) are also using Euclid’s data to identify supermassive black holes, investigate galaxy evolution, and make precise photometric measurements of transient objects.
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Euclid has already completed week-long observations of each of its three deep fields, marking the beginning of its most detailed investigations. With just a single scan of each region, Euclid has identified 26 million galaxies, some as distant as 10.5 billion light-years away. Galaxy shapes and distances are discerned using the high-resolution visible imaging instrument (VIS), while the near-infrared spectrometer and photometer (NISP) determine distance and mass.
Meanwhile, scientists at Munich’s Ludwig Maximilian University (LMU) have developed crucial identification methods to analyze cosmic regions with greater-than-average density, known as “overdensities.”
“The methodologies used to pinpoint galaxy clusters in this task will be key to fully exploiting Euclid’s vast dataset, improving cluster identification and contributing to a deeper understanding of cosmic structure formation. At the same time, they help explore previously uncharted regimes in the near-infrared with a statistically significant sample of objects,” says LMU scientist Barbara Sartoris.
The three deep field previews can now be explored in ESASky.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted atryan@thedebrief.org, and follow him on Twitter@mdntwvlf.