From John Mather (NASA/GSFC) and Eric Smith (NASA/HQ)

26 May 2005

The JWST cost estimates have increased significantly, and now far exceed the program budget. These increases come from a combination of additional required work, schedule slip, the delay in a firm decision to accept the Ariane 5 launch vehicle offered by ESA, and increased reserves to meet NASA standards. As a result, NASA Headquarters has directed the JWST project to evaluate technical options, and plans to establish a Tiger Team of scientists to work with the JWST Science Working Group to prioritize the capabilities of JWST, based on recent scientific progress and on changes to other available observatory astronomical capabilities in space and on the ground.

One bounding case study was already completed. If the mission requirements were relaxed to such a degree that the mirror area were reduced by half, the instruments need cover only 1 to 5 microns, and the spectrograph need not have a multi-object capability, then less than half of the JWST objectives in the current NASA roadmap could be completed. The descoped JWST would be not be able to observe the first galaxies in the early universe, the most important original objective. This reduced capability mission was still projected to exceed the current program budget.

Currently, in collaboration with its international partners, NASA intends to use the prioritized capability report to generate alternate mission plans that match the available resources. Once these plans are developed NASA will work with its partners and the scientific community to select the best mission to proceed forward in the full context of the NASA space science portfolio.