Investigating Dark Energy: Collaborative Endeavors of NASA’s Roman and ESA’s Euclid Space Telescopes

High-definition depiction of Euclid and Roman spacecraft set against a celestial backdrop. Credit: NASA’s Goddard Space Flight Center, ESA/ATG medialab

The Nancy Grace Roman Space Telescope by NASA and the European Space Agency’s (ESA) Euclid Telescope are partnering to explore the enigmatic acceleration of the universe’s expansion. Utilizing specialized techniques, the two telescopes aim to illuminate our understanding of dark energy, cosmic acceleration, and patterns of universal expansion.

Launched in July, the Euclid telescope is an ESA mission with significant contributions from NASA. Its purpose is to investigate the rapid expansion of the universe, attributed to an unknown force referred to as “dark energy.” By May 2027, the Nancy Grace Roman Space Telescope will supplement Euclid’s efforts, exploring these cosmic questions through methods hitherto unattainable.

“Even after a quarter-century since its discovery, the accelerating expansion of the universe remains a crucial enigma in astrophysics,” remarked Jason Rhodes, Senior Research Scientist at NASA’s Jet Propulsion Laboratory. Rhodes holds the position of Deputy Project Scientist for the Roman telescope and is the U.S. scientific head for Euclid. “These forthcoming telescopes will offer unprecedented precision in measuring dark energy, ushering in a new epoch of cosmic exploration.”

Examining the Underpinnings of Cosmic Expansion

Astronomers remain uncertain whether the acceleration of the universe’s expansion is the result of an additional energy force or signifies a need to revise our understanding of gravity. Roman and Euclid will simultaneously test both hypotheses, and scientists anticipate that the missions will reveal critical insights about the universe’s foundational mechanisms.

Roman and Euclid have distinct yet synergistic strategies for probing cosmic acceleration. They will construct three-dimensional cosmic maps to answer pivotal questions concerning the universe’s history and architecture. Combined, their capabilities will far exceed what either could accomplish independently.

Euclid will survey a substantially larger portion of the sky, approximately 15,000 square degrees, in both infrared and optical light spectra but with less granularity than Roman. It aims to observe the universe as it existed roughly 10 billion years ago. Roman, in contrast, will examine a more limited area with greater depth and accuracy. Its infrared capabilities will allow it to explore the universe at around 2 billion years of age and reveal a larger number of less luminous galaxies.

Unraveling the Mystery of Dark Energy

The universe has been expanding since its inception— a discovery attributed to Georges Lemaître in 1927 and later confirmed by Edwin Hubble in 1929. However, this expansion was initially expected to decelerate due to gravitational forces. Contrary to these expectations, in the 1990s, scientists discovered that the influence of dark energy began to predominate about 6 billion years ago. This revelation indicates a significant gap in our cosmic understanding.

Roman and Euclid will generate a series of robust new datasets to address these knowledge gaps. They plan to pinpoint the cause of cosmic acceleration via various approaches. One such approach involves studying weak gravitational lensing—a phenomenon where the mass of an object distorts the space-time fabric, thereby affecting the trajectory of light. By observing these distortions, both telescopes will create three-dimensional maps of dark matter, providing clues to the forces opposing universal expansion.

Furthermore, Roman and Euclid will scrutinize the clustering of galaxies across different eras of cosmic history. This will allow scientists to compare theories of modified gravity with the existence of an unknown energy component as potential explanations for cosmic acceleration. Roman will also undertake an additional study to observe type Ia supernovae—unique exploding stars—providing further insight into the history and behavior of dark energy.

A Synergistic Approach to Cosmic Exploration

The survey areas of Euclid and Roman will overlap, allowing scientists to calibrate Euclid’s observations using Roman’s more precise data. “Euclid’s initial observations will set the stage for Roman’s more in-depth examination,” stated Mike Seiffert, the project scientist responsible for NASA’s contribution to Euclid at NASA’s Jet Propulsion Laboratory.

Yun Wang, a senior research scientist at Caltech/IPAC who has headed galaxy clustering science teams for both telescopes, added, “In tandem, Euclid and Roman will far exceed the sum of their individual contributions, furnishing astronomers with a more comprehensive understanding of cosmic phenomena.”

Multiple NASA-affiliated scientific groups are contributing to Euclid. Besides designing and fabricating key sensor-chip electronics for Euclid’s Near Infrared Spectrometer and Photometer, NASA’s Jet Propulsion Laboratory oversaw the procurement and delivery of these detectors, which were subsequently tested at NASA’s Goddard Space Flight Center. The Euclid NASA Science Center at IPAC will facilitate U.S.-based research initiatives using Euclid data.

The Nancy Grace Roman Space Telescope is managed at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. It includes collaborations from NASA’s Jet Propulsion Laboratory and Caltech/IPAC in Southern California, the Space Telescope Science Institute in Baltimore, and a collective team of researchers from various institutions. Key industrial collaborators include Ball Aerospace and Technologies Corporation, L3Harris Technologies, and Teledyne Scientific & Imaging.

Frequently Asked Questions (FAQs) about Dark Energy Exploration by Telescopes

More about Dark Energy Exploration by Telescopes

• Nancy Grace Roman Space Telescope Official Website
• ESA’s Euclid Mission Overview
• Weak Gravitational Lensing Explained
• Cosmic Acceleration and Dark Energy
• NASA’s Goddard Space Flight Center
• Space Telescope Science Institute
• Jet Propulsion Laboratory
• Caltech/IPAC
• Ball Aerospace and Technologies Corporation
• L3Harris Technologies
• Teledyne Scientific & Imaging
• Type Ia Supernovae and Cosmic Expansion
• 3D Mapping of the Universe