Hubble's Proposed Supersize Successor Generates Controversy

Any award for the most productive observatory in history would certainly go to the Hubble Space Telescope. But the Hubble's days are numbered—its instruments and orbit continue to degrade—and its inevitable demise will result in a significant data-collection gap for astrophysics and cosmology. Because Earth's atmosphere filters out most ultraviolet wavelengths, they are accessible only from space, where Hubble lives. Neither of NASA's next-generation observatories—the 6.5-meter James Webb Space Telescope and a 2.4-meter repurposed infrared spy satellite called WFIRST—will fill these wavelength gaps. “When Hubble goes, it goes,” says John Mather, a Nobel laureate astrophysicist at the NASA Goddard Space Flight Center. “And we don't have anything else on the books that does what it does.”