In a clean room at the Goddard Space Flight Center in Maryland, the light-collecting heart of NASA’s next great space telescope is finally coming together. For the last several weeks, technicians, aided by a robotic arm, have been putting hexagonal mirror segments into a structure for the James Webb Space Telescope (JWST). As of last week, 13 of the 18 mirror segments were in place, with all 18 expected to be in position by the end of February.
The assembly of JWST’s primary mirror is just one aspect of the telescope’s construction. Elsewhere, the telescope’s instruments are being tested while the spacecraft bus and its deployable sunshade, the size of a tennis court, are put together. Several years after a critical “replan” of the observatory, years behind its original schedule and billions of dollars over its original budget, NASA says JWST remains on track for launch on an Ariane 5 in October 2018.
That means that spending on JWST—$620 million for the 2016 fiscal year—will soon ramp down. For several years, NASA had been anticipating the “wedge” in the budget this would create and started planning for the next large space observatory beyond JWST that wedge of funding would enable. The leading candidate for that mission has been a concept called the Wide Field Infrared Survey Telescope (WFIRST), one endorsed by astronomers as their top priority large mission in their latest decadal survey in 2010.
WFIRST, as it turns out, will start even sooner that NASA expected. At the 227th Meeting of the American Astronomical Society (AAS) held last week in Florida, agency officials announced that WFIRST will “enter formulation” in February. That milestone, also known in NASA’s project management terminology as “Key Decision Point A,” sets WFIRST on course for a launch in the mid-2020s.