NASA’s Roman and ESA’s Euclid to join forces to study dark energy

Together, the tools will explore why the universe’s expansion is speeding up.
Loukia Papadopoulos
An illustration of the Euclid telescope.jpg
An illustration of the Euclid telescope.


A space telescope called Euclid, an ESA (European Space Agency) mission, will launch tomorrow to explore why the universe’s expansion is speeding up, also known as “dark energy.” By May 2027, NASA’s Nancy Grace Roman Space Telescope called Roman will join Euclid in the sky to aid in the discovery of this mystery.

This is according to a press release by NASA published on Tuesday.

“Twenty-five years after its discovery, the universe’s accelerated expansion remains one of the most pressing mysteries in astrophysics,” said Jason Rhodes, a senior research scientist at NASA’s Jet Propulsion Laboratory in Southern California. Rhodes is a deputy project scientist for Roman and the U.S. science lead for Euclid. 

“With these upcoming telescopes, we will measure dark energy in different ways and with far more precision than previously achievable, opening up a new era of exploration into this mystery.”

Scientists still don’t know whether the universe’s accelerated expansion is caused by an additional energy component, or whether we need to update our understanding of the force in some way. Roman and Euclid will test both these theories at the same time.

Although both Euclid and Roman are designed to study cosmic acceleration, they will use different and complementary strategies to do so. 

The similarities

Both missions will make 3D maps of the universe that together will be much more powerful than either individually.

The differences

Euclid will study a far larger area of the sky than Roman (approximately 15,000 square degrees which amounts to about a third of the sky). It will do this in both infrared and optical wavelengths of light.

“Euclid’s first look at the broad region of sky it will survey will inform the science, analysis, and survey approach for Roman’s deeper dive,” said Mike Seiffert, project scientist for the NASA contribution to Euclid at NASA’s Jet Propulsion Laboratory.

Roman on the other hand will examine the universe to a much greater depth and precision, but over a smaller area (about 2,000 square degrees).

Roman will conduct an additional survey to discover many distant type Ia supernovae and study the light of these celestial objects to find out how quickly they appear to be moving away from us in order to trace cosmic expansion over time.

“Together, Euclid and Roman will add up to much more than the sum of their parts,” said in the statement Yun Wang, a senior research scientist at Caltech/IPAC in Pasadena, California, who has led galaxy clustering science groups for both Euclid and Roman. “Combining their observations will give astronomers a better sense of what’s actually going on in the universe.”