I'd like to see them shipping it to the ISS and testing on a smaller scale, then attaching main sale to craft if all works ok..

IIRC one of the biggest problems is the funding was cut to near zero one year. People have to have food on the table. Not everyone could wait around a year to be brought back on the project.

There seem to be two big issues left. The first seems to be some sort of engineering and building screw up at NGAS on the propulsion system. That isn't being talked about. If they have identified it they will fix it.
The second seems to be the sun shield. Never flown before. Seems like they tried something and it didn't test okay. Rinse and Repeat. Does not give good confidence all the problems are out.

It seems to be an issue to unfold and unfurl things in space. Skylab, ISS, Light Sail, there is a list of failures of those kinds of operations. We don't have zero g test facility for those.

If the launch of the telescope is postponed for 3 years, then this indicates that there are fundamental problems.
Disclosure of the solar shield is not a fundamental problem. Disclosure of the design in space has long been worked out and with this there are no problems.
The telescope has 18 independent mirrors, which must be controlled and must be self-tuning.
Probably, when testing the telescope, theoretical calculations were not achieved. The telescope did not give positive results. I mean the mirror. Each mirror has its own control and adjustment system.
Mirror is the most important thing that is in the telescope and if they do not work, then the telescope is useless.

3 years is a long time, for small problems.

A meer spec in human time

The "tuning" of multiple mirrors for large telescopes has been around for a few years now, and is approaching a "mature" technology. However the solar shield is something new, not in concept but in the way it is folded and packed for launch - think of origami on a giant scale. A bit more or less friction in one of the hinges and the thing won't unfold properly. so the whole thing has to be taken to bits again, re-worked, re-tested, then re-integrated with the rest of the telescope, the telescope re-tested....
Also reported earlier in this thread there are reports that there are (or have been) issues with one of the propulsion/positioning modules - which are sort of essential for making sure the telescope is where it should be and pointing in the right direction. Again lots of time required to sort that out (basically the same process needed as that for the Sun shield.

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Bob Smith
Member of Seti PIPPS (Pluto is a Planet Protest Society)
Somewhere in the (un)known Universe?

Amazing Russian Scientist who sits on own hands tells all what where doing wrong, while NASA and others search the cosmos, Russian Scientist Vadim Rybin tells all..

Amazing Russian Scientist who sits on own hands tells all what where doing wrong, while NASA and others search the cosmos, Russian Scientist Vadim Rybin tells all..

He's merely espousing very Russian biased opinions and points of view. Very few of if any I agree with but like all other members here, as long as he stays within the rules that's his prerogative . Ain't gonna make many friends or win over the rest of us to his unique point of view but I enjoy reading some of his comments.

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Bob DeWoody

My motto: Never do today what you can put off until tomorrow as it may not be required. This no longer applies in light of current events.

When Russia can send spacecraft like NASA, Space X, Blue Origin and others with scientific stuff that can help all (Other than Boast there new weapons and some have failed) until then, they should remain silent..

Vadim, you seem to forget that the major portion of the ISS was delivered into orbit by the US space shuttle, now retired. I think it was a mistake to retire it before it's replacement was ready but I'm not in charge. Pretty soon though the rest of the world's countries with astronauts won't be having to pay Russia for a ride to the ISS.

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Bob DeWoody

My motto: Never do today what you can put off until tomorrow as it may not be required. This no longer applies in light of current events.

For example, the telescope "Kepler" failed because of the positioning system.

Yes, after its design lifetime had been exceeded. Also note Kepler was built as a cheap mission.

Same type of system, reaction control wheel, has failed on every spacecraft it is on including the ISS. Humans can't make bearings and electric motors that last forever.

Perhaps in James Webb, a modular assembly is used and there will be the possibility of replacing the positioning system and other systems.

The James Webb's location in space will be too far out to allow maintenance.

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The mind is a weird and mysterious place

Kepler is a modular system, just not one designed for maintenance. One problem, as I understand, is that the modules that are failing are actually buried deep within the craft - they have to be close to its "centre of gravity" to work properly. Additionally the craft is running out of fuel for maneuvering, and refueling a spacecraft is somewhat more complex than filling up one's car.
Much the same applies to the JWT - fuel will be one of the biggest determining factors on its life, other components will be degraded by the continuous exposure to solar radiation, micro-meteors and "space debris".

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Bob Smith
Member of Seti PIPPS (Pluto is a Planet Protest Society)
Somewhere in the (un)known Universe?

Latest news

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rOZZ
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Money helps build telescopes.

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There is a simple test to detect spherical aberrations, the Ronchi test, which needs only a candle and a knife. Probably the builders of the optical section did not know it, or they thought it was old stuff.
Tukllio

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There is a simple test to detect spherical aberrations, the Ronchi test, which needs only a candle and a knife. Probably the builders of the optical section did not know it, or they thought it was old stuff.
Tukllio

They knew it, they just thought their tests covered it, they didn't.

He who pays the piper calls the tunes.
Tullio

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I think there is a way to present an astronomy project and ask for time on a telescope. Astronomers are kind people and will consider your request as far as possible.
Tullio

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Lets NOT forget that it's really hard to listen radio waves even from our solar system. No 4k pics from Mars any time soon.

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Why is the James Webb Space Telescope taking so long?
https://www.youtube.com/watch?v=k8yRDrl76d0

I also think they keep on postponing it because they cannot say goodbye to the Hubble. The Hubble will be sorely missed once it's gone.

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rOZZ
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Hubble receives visible light, Webb should cover the IR range, hence it must be cooled.
Tullio

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