Commentary: Astronomy from space after the JWST

Abstract

Last year the James Webb Space Telescope (JWST) trained its sights on the distant universe and began returning stunning images in IR light that captured the imagination of the public around the world. The JWST has only just begun its exploration of the universe, yet astronomers are already looking to the future. Every 10 years, panels of experts convened by the National Academies create a survey in astronomy and astrophysics to assess scientific frontiers and plan the capabilities that will keep advancing humankind's understanding of the cosmos. The JWST, originally called the Next Generation Space Telescope, was recommended as the top-priority large strategic mission in the 2000 decadal survey, and given its technical ambition and scale, it took more than two decades to be realized. But it was also conceived as costing less than 10% of the eventual price tag, in part because of wishful thinking by NASA and the scientific community and in part because the project began full-scale development before it was ready. The 2010 decadal survey gave the highest priority for a large space mission to the Nancy Grace Roman Space Telescope, then known as the Wide-Field Infrared Survey Telescope, an observatory that will image large swaths of the sky in IR light to make three-dimensional cosmic maps of many millions of galaxies, elucidate the nature of the mysterious dark matter and dark energy, search for and image exoplanets, and explore many other topics in IR astrophysics. Roman is scheduled for launch in 2027, some 17 years after it was recommended as a priority. That delay was a result of funding issues directly related to the cost overruns on the JWST. Like the JWST, Roman was chosen to address the big, outstanding scientific questions identified at the time. But the delays bring with them costs in both taxpayer dollars and scientific opportunities. The most recent astronomy and astrophysics survey, Astro2020 (for which the two of us served as committee cochairs), considered how to accomplish its charge to chart a course for the future of space astrophysics. In previous surveys, the committees have provided a rank-ordered list of concepts for large space missions, and in the decade that followed, NASA began development of the top project on the list as its next priority. Astro2020, however, took a different course.

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