NASA Prepares to Launch $4.3 Billion Roman Telescope

The observatory has an improbable origin. About fifteen years ago, as NASA drew up plans for a telescope capable of hunting the exploding stars known as Type 1a supernovas, the National Reconnaissance Office (NRO), the agency responsible for American surveillance satellites, offered an unused spacecraft sitting in a hangar. Cosmologist Daniel Scolnic of Duke University recalls the proposal simply: instead of pointing the instrument downwards, point it upwards. After substantial modification, that surplus satellite became a flagship science mission. Roman matches the sensitivity and sharpness of the Hubble Space Telescope but sees a field of view at least a hundred times wider. Project scientist Julie McEnery says a single month of Roman observations would survey the Milky Way in work that would occupy Hubble for roughly a century.

Astronomers hope the telescope will measure dark energy, the mysterious force driving cosmic expansion, settle whether the standard model of that expansion is correct, map billions of galaxies, probe black holes and detect planets invisible to other methods. Scott Gauti of Ohio State University expects Roman to find distant worlds through gravitational microlensing, an effect Albert Einstein described in 1936 but dismissed as impractical. The mission is designed to last five years, with hopes of ten, and its catalogues will be released publicly, so a high-school class can examine the same data as a university professor. Wendy Freedman of the University of Chicago cautions that new instruments usually deliver surprises nobody predicted.