Webb Telescope the Good and Bad
James Webb Telescope Makes Progress But at What Cost?, SpaceRef
“NASA’s Goddard Space Flight Center released the following list of highlights for the James Webb Telescope for 2012 marking the progress of the project. However while the project is making progress, it has created budgetary problems for NASA and will launch several years later than planned.”
One of you readers poits out: “Although I am glad to see James Webb making progress, as a NASA Glenn employee I must object to the statement under Chamber A “the largest thermal vacuum chamber in the world”. The Space Power Facility (SPF) at Plumbrook station is listed by Guinness Records as the worlds largest vacuum chamber. Its dimensions, 100 diameter by 122 feet tall, are considerably bigger than the 55 foot diameter by 90 foot tall Chamber A. SPF has been used for thermal vacuum testing as well.”
The SPF was considered and rejected for various logistic and technical reasons early in the JWST program.
Testing decisions in long duration programs are made very early in schedule, and have great impact on the program’s performance. For example 2005 JWST decision to test at JSC Chamber A (instead of much larger GRC Plumbrook SPF T-Vac chamber) was made to avoid building a $40M runway at test site. To save this $0.04B capital expense, the $8B JWST program will sacrifice full-scale thermal vacuum test prior to launch. I hope this decision works out for JWST; but recall that HST did not undergo a full-scale thermal vacuum test prior to launch and had to be refitted with a high tech form of eyeglasses (at great expense, because optometry in earth orbit is REALLY EXPENSIVE).
SAVE MONEY, TEST FIRST
HST did have a full-scale thermal vacuum test at Lockheed. To be fair the test did not include an optical simulator, but tests during the figuring of the primary already showed that there was a problem. The tests unfortunately were ignored in favor of the results from a flawed null-tester, but this was never justified…
Thanks for the bit of history Tod. Illustrates that full scale testing (including optics) is critical. The 2005 justification to move TVAC testing from SPF to Chamber A stated SPF was not capable of optical testing. That was disproved; SPF is capable of optical testing.
The 2005 justification to move TVAC testing from SPF to Chamber A stated SPF was not capable of optical testing.
I don’t know where you get your information.
The analysis of each facility’s capabilities was quite extensive and thorough.
Even getting the telescope to and from the facility was a logistics nightmare.
NASA would have had invest significant $$ to upgrade the SPF for this test, and since the future usefulness of the facility is very limited, it was the consensus that the money required was not worth it.
obvious boondoggle is obvious
I predict JWT will never fly and be canceled due to cost overruns and production delays. If it does,its longevity will prove to be short lived. A cheaper,more cost effective telescope would be a better investment.
I don’t know what a “cheaper, more cost effective” telescope would be. JWST is just about at the lower limit of the size needed for the astrophysics set out for it to do – indeed, it was originally to have been an 8m. The primary size gives it NIR spatial resolution that will match HST’s optical resolution, and a collecting area that will enable the detection of objects with 1 nJy flux, which is where you need to be for forming objects at z > 6. The Hubble runs out of steam for the phase of the Universe coming out of the great dark ages. One might imagine a telescope half-way between JWST and HST, but its science would be incremental rather than revolutionary.
“One might imagine a telescope half-way between JWST and HST, but its science would be incremental rather than revolutionary.”
Yeah, but for $9 billion, you get so many increments.
How much would the development of a new payload fairing for an existing launch vehicle capable of accommodating a 6 to 8m monolithic mirror have cost? Would it have been less than the amount swallowed in cost overruns for this elaborate fold-out origami structure?