Spent some time From: 1967 to 1971; employed by the USGS - Dept of Interior as Electronic Engineering Tech during the first man to the Moon programs were being done! I Was part of this scenario and familiar with much of it! Later was attached with the Space Shuttle team working out of Huntsville Army Missile base** The remaining data is from the Chief Engineer! ** This is very complicated. I have to explain why. When I was the chief systems engineer for SBL-IFX[1] , the space-based laser, my initial approach was to build it with the maximum likelihood of working.

Date:   12/23/2021 12:48:43 AM ( 3 y ago)

What are the benefits of James Webb Telescope over Hubble?

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Bill Otto,
former Lead Systems Engineer, Space Based Laser (2000-2001)
Answered Oct 16, 2021 ·

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Matthias Jaeger
, PhD Astronomy, Heidelberg University and
Richard Holl
, former Engineer at NASA (1961-1971) · Author has 7K answers and 32M answer views

This is very complicated.

I have to explain why. When I was the chief systems engineer for SBL-IFX[1] , the space based laser, my initial approach was to build it with the maximum likelihood of working. I was thinking Hubble size, because twenty years ago, that was as large as a monolithic mirror could be and still be launched by the Air Force launch vehicles of the time (Atlas-V - Lockheed and Delta-IV- Boeing).

Word got around about what I was saying in meetings. I started getting phone calls from retired generals, directors of government agencies, retired directors, anyone with name recognition who might be a little intimidating to me. Mostly they said that we already had Hubble-sized telescopes in space. This was an allusion to the subject we could not openly discuss: NRO[2] satellites. NRO did not officially exist at the time.

Basically most of them said I would “need" to launch something larger, better, more “sexy" to get their political support. At that point, I started shifting the emphasis from practical to larger, just for show. We also moved our integration and test facility to Stennis[3] to get Trent Lott’s[4] support. Many of you know that SBL-IFX was canceled to help pay for the Gulf War after 9/11.

The NGST[5] (later renamed to JWST) was under even more pressure than I was. It wasn't enough to be a larger telescope, it had to pioneer a new technology and be a new paradigm for light-weight smart structures in space. They got so excited that they set nearly impossible mass and performance goals that were so far beyond the technology of the late 1990s that they went twenty times over the original budget and three times over the original schedule.

Of course, whatever NASA developed would be available to the defense agencies. Meantime, FIA[6] , the NRO version of Next Generation Space Telescope, failed because the Nunn-McCurdy Act[7] caused Congress to investigate an over run. (Rather than have a public investigation, they folded up shop.) The act does not apply to NASA, so they kept going. Finally, Congress capped their costs, so they had to get European funding.

The bottom line here is that political pressures pushed NASA into a new technology that was not ready. Everything about JWST had to be invented from scratch because existing technology did not fit the bill.

As in the original space race, the benefits of these technologies will be with us for a long time. The JWST is a good six times the area of the Hubble. That is one giant leap. Why? Well, a combination of the political pressure and something else that we released. It is called adaptive optics. It is something I was involved with almost from the time I graduated in 1976. But it did not become declassified until the 1990s. After that, it became practical to build large ground-based astronomical telescopes. There was an explosion in the astronomical community to build larger telescopes.

This put all the more political pressure on JWST to stick to the large size no matter how difficult or expensive. It will give us better resolution and more light gathering than Hubble, with an emphasis on near to longwave infrared rather than visible. One problem for NASA is that in the 20 years that JWST has been under construction, larger ground based telescopes have already surpassed the Hubble, making it somewhat obsolete[8] . So the benefit of JWST will also be that it can see in bands that ground based telescopes can not see.

So that's why I said that it is complicated.

To appease Paul Manhart, I will summarize the benefits:

A number of light weight, low temperature technologies for structures, electronics, sensors, actuators and so on
a larger primary mirror than Hubble, giving higher resolution and more light collecting capability
the ability to observe in the infrared wavebands
onboard wavefront sensing technology to correct the shape of the primary mirror in real time

Footnotes
[1] http://www.wslfweb.org/docs/SBLWP.pdf
[2] Home
[3] NASA's Stennis Space Center
[4] Trent Lott - Wikipedia
[5] The Next Generation Space Telescope (NGST)
[6] Future Imagery Architecture [FIA]
[7] Facts: Nunn-McCurdy Act (10 U.S.C. §2433)
[8] Neptune from the VLT and Hubble
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