Author Topic: How much political support does JWST have?  (Read 9230 times)

Offline Mark S

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Re: How much political support does JWST have?
« Reply #20 on: 04/20/2012 03:54 PM »
An Orion could get there if needed, using iCPS or possibly Block-2 CPS. Seems like this would fit in perfectly with Orion's primary role as NASA's manned deep space spacecraft.

Mark S.

Online Blackstar

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Re: How much political support does JWST have?
« Reply #21 on: 04/20/2012 04:20 PM »
It is absolutely, totally, completely, 110% NOT SERVICEABLE.

For starters, that big solar shade cannot be retracted. Hit that with the RCS thrusters and it folds up around the spacecraft like a plastic bag and you might as well turn around and go home.

In addition, the mirror is cold. Orion will outgas. Orion will put out RCS gas. That will condense on the mirror and ruin it.

There is no attachment point for a spacecraft.

The components are not designed to be removed for replacement.

The spacecraft has sharp edges.

I could go on and on.
« Last Edit: 04/20/2012 04:20 PM by Blackstar »

Online Robotbeat

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Re: How much political support does JWST have?
« Reply #22 on: 04/20/2012 04:27 PM »
ESL-2 is very, very close (delta-v-wise) to EML1/2. James Webb probably has enough on-board propellant to bring itself to EML1/2 by itself (especially using a low energy transfer a.k.a. a weak stability boundary trajectory), and there's supposed to be a docking port so that another (unmanned) spacecraft could do it, as well.

Still, that doesn't mean a servicing mission would make any sense (see Blackstar's extensive post above mine).

So, has the NDS/iLIDS docking port been deleted?
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline Mark S

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Re: How much political support does JWST have?
« Reply #23 on: 04/20/2012 05:09 PM »
It is absolutely, totally, completely, 110% NOT SERVICEABLE.
....
I could go on and on.

Well then, just be prepared for the backlash when JWST becomes a $9 billion piece of space junk because someone overtightened a wingnut or something.

It's not smart for it to be absolutely, totally, completely, 110% NOT SERVICEABLE.

Mark S.

Online Blackstar

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Re: How much political support does JWST have?
« Reply #24 on: 04/20/2012 09:53 PM »
1-Well then, just be prepared for the backlash when JWST becomes a $9 billion piece of space junk because someone overtightened a wingnut or something.

2-It's not smart for it to be absolutely, totally, completely, 110% NOT SERVICEABLE.

1-Why should I be prepared for backlash? I didn't build it.

2-Tell us what it would cost if it was designed to be serviceable.

Offline spectre9

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Re: How much political support does JWST have?
« Reply #25 on: 04/20/2012 10:31 PM »
I read stuff like this and find it hard to disagree.

A servicing mission costs less than a new telescope. Maybe?

Online Robotbeat

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Re: How much political support does JWST have?
« Reply #26 on: 04/20/2012 10:35 PM »
I read stuff like this and find it hard to disagree.

A servicing mission costs less than a new telescope. Maybe?
If you have a REALLY expensive, big telescope and a really pared-down commercial-type repair mission, maybe. But it'd probably have to be a different telescope than JWST (bigger, not as fragile) and it'd probably have to be in a world where non-NASA commercial crew orbital missions happen several times a year. Not impossible.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline Mark S

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Re: How much political support does JWST have?
« Reply #27 on: 04/20/2012 11:08 PM »
I read stuff like this and find it hard to disagree.

A servicing mission costs less than a new telescope. Maybe?

Thanks for that document, spectre, it's very informative and actually relevant. :)

Offline Mark S

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Re: How much political support does JWST have?
« Reply #28 on: 04/20/2012 11:23 PM »
1-Well then, just be prepared for the backlash when JWST becomes a $9 billion piece of space junk because someone overtightened a wingnut or something.

2-It's not smart for it to be absolutely, totally, completely, 110% NOT SERVICEABLE.

1-Why should I be prepared for backlash? I didn't build it.

2-Tell us what it would cost if it was designed to be serviceable.

1-Sorry if I worded that poorly. I didn't mean that you personally are risking backlash, unless of course you're the decision maker on JWST design. NASA should be prepared for potential backlash for making JWST unserviceable.

2-Would it cost less to design in some minimal level of serviceability than to build an entire new telescope in case of failure of any kind? Is it worth risking the entire mission by making it anti-serviceable?

NASA got a pass on HST because they fixed it and it worked perfectly afterwards. Do you think Congress would have paid for a second HST if the first had been unserviceable and unfixable? I don't think so. I think they would have been laughed out of the room.

Has that scenario been ran past the appropriate committees? "If JWST fails, there is no way for us to fix it. So this is just a heads-up so you can be ready for us to come back and ask for another $9 billion in that case. And oh by the way, even if everything works perfectly, JWST will only work for 5 or 10 years tops. Later dudes!"

That doesn't really sound like responsible planning to me, but what do I know, I'm just a taxpayer.

Mark S.

Offline spectre9

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Re: How much political support does JWST have?
« Reply #29 on: 04/20/2012 11:26 PM »
The possibility of commercial crew servicing is interesting.

Dragon on Falcon Heavy? Instruments and robot arms in the trunk?

Could be quite a bit cheaper than SLS/Orion.

Online Blackstar

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Re: How much political support does JWST have?
« Reply #30 on: 04/21/2012 05:44 PM »
The possibility of commercial crew servicing is interesting.

Dragon on Falcon Heavy? Instruments and robot arms in the trunk?

Could be quite a bit cheaper than SLS/Orion.

Dragon and F9H seem to be the magic fairy dust for the space program--just sprinkle it on any problem and it is instantly solved.

Online Blackstar

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Re: How much political support does JWST have?
« Reply #31 on: 04/21/2012 05:47 PM »
1-Sorry if I worded that poorly. I didn't mean that you personally are risking backlash, unless of course you're the decision maker on JWST design. NASA should be prepared for potential backlash for making JWST unserviceable.

Why? Don't you think they had their reasons? You might speculate about what those reasons were.

"Serviceability" is not automatically a good thing.

Online Blackstar

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Re: How much political support does JWST have?
« Reply #32 on: 04/21/2012 05:52 PM »
2-Would it cost less to design in some minimal level of serviceability than to build an entire new telescope in case of failure of any kind? Is it worth risking the entire mission by making it anti-serviceable?

NASA got a pass on HST because they fixed it and it worked perfectly afterwards. Do you think Congress would have paid for a second HST if the first had been unserviceable and unfixable? I don't think so. I think they would have been laughed out of the room.

Has that scenario been ran past the appropriate committees? "If JWST fails, there is no way for us to fix it. So this is just a heads-up so you can be ready for us to come back and ask for another $9 billion in that case. And oh by the way, even if everything works perfectly, JWST will only work for 5 or 10 years tops. Later dudes!"

First, the most likely failure mode is probably a launch failure. Serviceability doesn't help you there.

Second, you can guard against having to service (to fix things) by doing better testing on the ground.

There are a lot of tradeoffs when it comes to serviceability. It costs money. And the designers (who aren't stupid people, by the way) have to balance the costs, the benefits, and what they could buy with that money.

There are several reasons to design serviceability into an observatory:

1-to fix problems
2-to extend the lifetime
3-to to replace instruments

Now 2 and 3 are synonymous, because the instruments are the things that are most likely going die first (that's the case for Hubble). And that takes you down another path. Can the instruments really benefit from being updated, or are you sort of stuck with replacing an existing instrument with a better version of the same thing?

If you look at the history of Hubble servicing, they were able to expand the instrument suite. They didn't just improve the instruments, they could do more things with the telescope. I think that's the case with optical/UV telescopes more than far infrared telescopes like JWST.

(more in another post)
« Last Edit: 04/21/2012 05:58 PM by Blackstar »

Online Blackstar

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Re: How much political support does JWST have?
« Reply #33 on: 04/21/2012 06:00 PM »
Now here's a tough question: does it make sense to design serviceability into a telescope that costs $8 billion, when it does not make sense to design serviceability into a telescope that costs $4 billion?

The answer may very well be yes, but the problem is that this is not possible for JWST--if it was ever going to be serviceable, it had to be designed for that from the very beginning. That train has left the station.

Offline spacetraveler

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Re: How much political support does JWST have?
« Reply #34 on: 04/21/2012 08:56 PM »
Second, you can guard against having to service (to fix things) by doing better testing on the ground.

Indeed, after the Hubble issue they found that the problem could have easily been detected on the ground and the mirror switched to the correctly ground backup one if the testing plan had been more robust. The JWST planners have learned from that and have a very robust test and integration plan for this telescope.

Offline Mark S

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Re: How much political support does JWST have?
« Reply #35 on: 04/21/2012 10:23 PM »
Okay guys, I was wrong. The JWST designers are obviously very smart, otherwise they wouldn't have been the ones chosen to build such an advanced piece of hardware.

Forgive me for entertaining any doubts about JWST and the decisions behind it. Clearly things have gone swimmingly from the start, so there is no reason to concerned about anything.

Mark S.

Online Blackstar

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Re: How much political support does JWST have?
« Reply #36 on: 04/21/2012 11:38 PM »
Okay guys, I was wrong. The JWST designers are obviously very smart, otherwise they wouldn't have been the ones chosen to build such an advanced piece of hardware.

Forgive me for entertaining any doubts about JWST and the decisions behind it. Clearly things have gone swimmingly from the start, so there is no reason to concerned about anything.

Mark S.

Can we see the specs for the telescope you would have designed instead?

Offline QuantumG

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Re: How much political support does JWST have?
« Reply #37 on: 04/22/2012 01:40 AM »
JWST has a design? I just figured they came up with that monstrosity by hacking one solution after another onto what came before... it's the most generous assumption.

Jeff Bezos has billions to spend on rockets and can go at whatever pace he likes! Wow! What pace is he going at? Well... have you heard of Zeno's paradox?

Offline spacetraveler

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Re: How much political support does JWST have?
« Reply #38 on: 04/22/2012 07:37 PM »
Obviously I don't think anyone is going to claim that there haven't been problems (specifically with budget and timelines). But that does not automatically lead to a conclusion that the project is going to fail just because the telescope is not serviceable. One of the big cost drivers is the amount of testing and verification that is necessary, increasing the amount of testing on the ground drives up the cost however that will lead to a greater chance of mission success.

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