While the famous Hubble Space Telescope is entering its fourth—and final—decade in operation, several new space telescopes are lining up to take over its mantle. The Nancy Grace Roman Space Telescope—formerly the Wide Field Infrared Survey Telescope (WFIRST)—matches its illustrious predecessor in many ways. The most important similarity is its 2.4-metre-diameter primary mirror, just like Hubble’s. It will therefore offer much the same light-collecting power, but it outclasses Hubble with a field of view spanning a sky area 100 times larger.

While the image resolution will be pretty much the same as Hubble’s, this vast field of view will enable millions of galaxies to be observed where Hubble could only see a few thousand. The Roman Space Telescope is thus primed to accomplish one of its main science goals, which is to deliver new insights into the mysterious “dark energy” making up 75% of all matter in the universe and driving its accelerating expansion. To do that, it will need to very precisely measure the universe’s expansion rate at different epochs.

Another of the telescope’s key missions will be to survey exoplanets by direct detection, using a coronagraph to mask the glare of their stars, and by studying the gravitational microlensing effects these planetary systems exert on images of distant stars. It is thus expected that more than 70,000 exoplanets could be detected, compared to the 5,000 currently known. The Roman Space Telescope will operate in the near infrared, complementing telescopes operating in other wavelengths, such as Hubble viewing out to the ultraviolet and the James Webb Space Telescope (JWST) to the far infrared.

NASA asked CNES to join this mission and France is among the select number of partner nations. The agency is partnering with the LAM astrophysics laboratory in Marseille, which is supplying certain mirrors for the coronagraph and contributing its expertise acquired on Europe’s Euclid space telescope to develop building blocks for processing data from the telescope’s Wide Field Instrument (WFI). CNES is overseeing France’s contribution, providing funding, coordinating activities and offering its technical expertise where required.