Engineers conduct a white light inspection on NASA’s James Webb Space Telescope in the clean room at NASA’s Goddard Space Flight Center, Greenbelt, Maryland. (NASA/Chris Gunn)

Recent word that the giant mirror of the James Webb Space Telescope is essentially complete is a cause for celebration, a milestone in the long march toward launching what will be the most powerful astronomical instrument ever.  NASA Administrator Charlie Bolden made the announcement at the Goddard Space Flight Center, with senior project scientist John Mather declaring that “we’re opening up a whole new territory of astronomy.”

Although liftoff isn’t scheduled until two years from now, the mirror’s completion has led to an intensifying of the far less public but also essential task of determining how precisely the JWST will be used.

This is a major issue because the observatory will be far more complicated with many more moving parts for astronomers than the Hubble Space Telescope and other predecessors, and a significant amount of the learning about how to make observations can’t be done until JWST is already in space.

But more pressing still is the fact that “JW” (as it is now commonly called) will fly for a limited time, and as of now cannot be repaired or upgraded once in space because it will be too far away.

So while astronomers and the public have grown accustomed to long-lived observatories like the Hubble and Spitzer space telescopes — which have been revolutionizing astronomy for decades now — JW has a planned mission duration of just five years. Should the instruments continue working after that, the observatory will nonetheless run out of necessary fuel in 10 years.

Especially for exoplanet astronomers who often have to focus on a particular star and planet over a substantial time, this means they need to learn the JWST ropes fast or miss out on a scientific opportunity of a lifetime.

Natalie Batalha, a member of the JWST Science Advisory Committee and project scientist for the Kepler mission, said that the logic of  the traditional proposal cycles and proprietary periods “threatens to stall the release of potentially important technical information keeping data out of the public domain until the five year nominal mission is well underway.”

“Because of the finite lifetime of JWST, we have an urgency here that we didn’t have with Hubble,” she told me.

“The JWST Science Advisory Committee recognized the need to get data into the hands of community scientists as early as possible to take full advantage of this so valuable but limited opportunity.”… Read more