It's humanity's self-unwrapping Christmas present.
Webb flies Ariane 5: watch the launch live on 25 December
81–90 of 188 posts
Re: Webb flies Ariane 5: watch the launch live on 25 December
#82I do have a question about JWST that I wasn't able to find a fine answer in other forums. A lot of people and engineers are saying that the JWST is a marvel of engineering, with truly inovative technical solutions and a giant step up compared to Hubble Telescope. And it does seems like so! However, I'm always baffled how everyone seems proud that the telescope has something like 200 SPOF during deployment, and if eve…
I suggest the book "Failure is not an option" by Gene Kranz, an Apollo flight director (played by Ed Harris in Apollo 13). He describes how the primary work of flight controllers in all missions is risk management. You are constantly balancing mission needs, fuel needs, mass needs, temperature needs, and etc etc.
I don't think that a raw metric of the number of SPOF is the right way to measure the risk of this spacecraft. It's a fun term for PR purposes (and emphasizing the risk here) but the actual risk posture is more complex.
I imagine that in the course of developing this, they worked out a possible strategy without all of those SPOF - but doing so doesn't eliminate the risk, and the impact to mission is likely massive.
Re: Webb flies Ariane 5: watch the launch live on 25 December
#83Will this be visually tracked? Like can we watch it to it's journey?
Re: Webb flies Ariane 5: watch the launch live on 25 December
#84Decades of meticulous planning and they couldn't give their teams a day off on Christmas? Of course it could be that consensus was this beats any other kind of activity that day in which case fair enough. :-)
Newton's birthday sounds like the perfect day for a rocket launch to me
He was born January 4th, using modern calendars.
Re: Webb flies Ariane 5: watch the launch live on 25 December
#85It's humanity's self-unwrapping Christmas present.
Love it :D
Re: Webb flies Ariane 5: watch the launch live on 25 December
#86We're told that since JWT will travel very far away before it unfolds and activates all its systems, there is no practical way to service it if something would go wrong. Why can't it unfold etc in Earth orbit, where a repair mission can be sent if needed, and then travel to its Lagrange point?
I suspect the deployed structure cannot handle the acceleration required for escape velocity. That also may require much more propellant. Then on top of that, we don’t have the capability for humans to service satellites other than the ISS. So this is all a moot point.
Interesting though.
Does that really matter without air resistance?
Depending on how high you actually bring it. Like 500km away from earth is still an orbit (I think that's Hubble's orbit) but how much force do you need or will happen?
Re: Webb flies Ariane 5: watch the launch live on 25 December
#87Earlier quoted context omitted.
That's literally what he is doing, isn't it? He thought something was off, and instead of spewing his opinion all over the place he requested information from folks more versed in the domain than him. He is literally being curious, not judgemental.
> I'm always baffled how everyone seems proud that the telescope has something like 200 SPOF during deployment, and if even one of them fails the whole mission could fail I see this as judgmental, am I wrong in that?
It expresses an opinion, but I don’t think that has to be judgmental. The OP has to explain their position in order to ask for additional information.
Re: Webb flies Ariane 5: watch the launch live on 25 December
#88Earlier quoted context omitted.
From the JWST wikipedia page: "In the 2005 re-plan, the life-cycle cost of the project was estimated at US$4.5 billion. This comprised approximately US$3.5 billion for design, development, launch and commissioning, and approximately US$1.0 billion for ten years of operations.[18] ESA is contributing about €300 million, including the launch.[84] The Canadian Space Agency pledged $39 million Canadian in 2007[85] and in…
Those numbers are completely obsolete; the final price tag was over $10B.
The CSA is contributing staff to operations as well, afaik.
A more recent source says this (found through wikipedia). Values all appear to be up to launch, and do not include operations.
NASA: 8,800m
ESA : 850m
CSA : 200m
------------
All : 9,850m
"Günther Hasinger, ESA director of science, estimated that Europe’s contributions to JWST, in the form of instruments and the Ariane 5 launch, to be about 700 million euros ($850 million), roughly the same as an ESA “M-class” science mission.
Gilles Leclerc, director general for space exploration at the Canadian Space Agency, said Canada’s contribution of an instrument and fine guidance sensors cost the agency about $200 million Canadian ($165 million) over 20 years. “This is an investment in discoveries of the universe,” he said.
NASA now estimates it will spend $8.8 billion on JWST through the spacecraft’s launch."[1][2]
Those numbers line up with a summary the Planetary Society put out.[3] That source includes info on the operations cost, at least for the US:
"The James Webb Space Telescope (JWST) is expected to cost NASA $9.7 billion over 24 years. Of that amount, $8.8 billion was spent on spacecraft development between 2003 and 2021; $861 million is planned to support five years of operations. Adjusted for inflation to 2020 dollars, the lifetime cost to NASA will be approximately $10.8 billion.
That is only NASA’s portion. The European Space Agency provided the Ariane 5 launch vehicle and two of the four science instruments for an estimated cost of €700 million. The Canadian Space Agency contributed sensors and scientific instrumentation, which cost approximately CA$200 million."
All three agencies will supply staff to support operations, which I guess makes sense since they've all contributed different instruments.[4]
[1] https://spacenews.com/jwst-launch-slips-to-november/
[2] https://en.wikipedia.org/wiki/James_Webb_Space_Telescope#Cos...
[3] https://www.planetary.org/articles/cost-of-the-jwst
[4] https://en.wikipedia.org/wiki/James_Webb_Space_Telescope#Par...
Re: Webb flies Ariane 5: watch the launch live on 25 December
#89Decades of meticulous planning and they couldn't give their teams a day off on Christmas? Of course it could be that consensus was this beats any other kind of activity that day in which case fair enough. :-)
Lots of European countries celebrate Christmas Evening (Dec 24) more than Christmas Day (Dec 25).
I wish for our Canadian friends that the telescope unfurls on Boxing Day.
Re: Webb flies Ariane 5: watch the launch live on 25 December
#90Earlier quoted context omitted.
I suspect the deployed structure cannot handle the acceleration required for escape velocity. That also may require much more propellant. Then on top of that, we don’t have the capability for humans to service satellites other than the ISS. So this is all a moot point.
Interesting though. Does that really matter without air resistance? Depending on how high you actually bring it. Like 500km away from earth is still an orbit (I think that's Hubble's orbit) but how much force do you need or will happen?
When rockets are firing lots of acceleration is applied that the delicate structures are only designed to handle when stowed. Think long arms on hinges. They can take acceleration in one axis, but not at 90 degrees to it.