Back On Track
The JWST team successfully passed the System Design Review on January 24-27. In this GSFC review, the major system engineers described the overall design or function of their subsystem or major test in the context of the mission requirements. This was a significant milestone on the path to the Preliminary Design Review (PDR), now re-scheduled for early 2008 due to financial constraints. However, the review of technical readiness portion of the PDR and NAR (called the T-NAR) retained the original January 2007 date.
The project and several independent review teams presented the technical and programmatic status of the JWST program to the NASA Administrator in the spring of 2006. The development progress remained excellent with all 18 mirror segments being machined at Axsys. The demonstrations of the Technical Readiness Level 6 for all major new technologies were on track for the T-NAR in early 2007. The chief concern voiced by the Special Review Team (SRT) was the low level of funding contingency over the next four years. However, this factor and the overall level of uncommitted contingency (~19%) were comparable to that of the Chandra development at the comparable development phase. NASA and TRW (now NGST) were able to manage the cost growth on Chandra so that its final development cost to launch (~ $3.7B in 2005 dollars, similar to JWST) was remarkably close to that anticipated seven years before launch (see Hefner & Davidson). The costs of JWST had not increased in the last year and would be the subject of the second portion of the NAR, now scheduled for early 2008 (near the PDR).
On the technical front, the NIRCam and MIRI teams passed their CDR in 2006 and proceeded into development of the flight instruments. In August 2006, a Northrop Grumman, ITT, STScI, and NASA team tested the thermal stability of a 1/6 section of the backplane at the MSFC X-Ray Calibration Facility (XRCF) developed for Chandra but now utilized extensively by JWST. The test results were very encouraging, with the section distorting in the crucial out-of-plane direction by less than 30 nanometers, meeting the design specifications. A similar test at Ball, using the speckle interferometer developed for the backplane test, showed that the Be segments could withstand the vibration and acoustic loads of launch without suffering permanent distortions.
In 2006, Northrop Grumman deployed a full-scale model of the Webb at GFSC in the spring and at the SPIE meeting in Orlando in June. Since 2006, the model continues to appear in many states and countries, always to an admiring crowd.