The James Webb Space Telescope, WFIRST, and the risks of thinking big

Yesterday the New York Times reported that WFIRST—a $1.6-billion NASA mission to help identify the origin of dark energy, find exoplanets, and elucidate star and galaxy formation, could be delayed for a decade. The cause of the delay? Another NASA mission, the $3-billion James Webb Space Telescope (JWST), which is itself beset with delays caused by cost overruns and, apparently, mismanagement.

WFIRST, which stands for Wide-Field Infrared Survey Telescope, and JWST have different, complementary goals, but they’re remarkably similar in other respects. Both missions will observe the cosmos from the second Lagrangian point , the spot beyond Earth’s orbit where an orbiting object is constantly in Earth’s shadow. And both missions will operate in the IR, the waveband best-suited for observing young distant galaxies.

The two missions share another distinction: Both were picked as the top priorities in the decadal surveys undertaken by the US National Academy of Sciences—JWST in the 2000 survey; WFIRST in the 2010 survey.

To win top ranking, the supporters of both missions had to convince the US astronomy community and their representatives on the decadal committees that the science would be worth the cost. Given that both missions, especially JWST, rely on new, untried technologies, estimating the cost was, and is, challenging.

If you want to learn more about the travails of both missions—the mismanagement and the political problems—I recommend you read the Times story. Nature covered JWST‘s tribulations in an October 2010 story entitled “The Telescope That Ate Astronomy .”

I don’t condone cost overruns or mismanagement. I do, however, support the ambitious goals that inspired JWST and WFIRST. Launching and operating a space-based observatory is expensive. To justify the investment, a mission must be more capable than its predecessors.

And not just two or three times more capable. At 25 square meters, JWST‘s primary mirror has 5.6 times more light-collecting area than the Hubble Space Telescope has. Deploying such a large mirror is inevitably challenging and costly. Given the current fiscal climate in the US, delaying JWST and WFIRST may also be inevitable. But it’s better than outright cancellation.