Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

James Webb Space Telescope emerges successfully from final thermal vacuum test

phys.org

Post reply on HN
Print view View original

71–80 of 165 posts

Re: James Webb Space Telescope emerges successfully from final thermal vacuum test

#71

Post by CydeWeys »

gnu8 wrote: post #36
NikolaeVarius wrote: post #7

Man, I really want this telescope to succeed its mission, but I just can't get over how complex its deployment procedure is. I am extremely pessimistic about it actually managing to deploy as planned.

I have read in other discussions that the contractor has great confidence in the deployment of the sun shield because of their experience with similar systems on classified satellites. I think as long as the launch is successful there won’t be any problems with the mission.

I really hope this is true, but there must still be something different, because there's been years of delay caused by the solar shade not deploying properly.

Re: James Webb Space Telescope emerges successfully from final thermal vacuum test

#72

Post by TeMPOraL »

mhb wrote: post #35
java-man wrote: post #27

what puzzles me all the time is why not build two instead. it looks like the R&D portion of the budget might be greater than the actual manufacturing cost, so building two would be less than 2x the price. if one launch fails, we've got a backup. if both launch, we have two instruments deployed. why don't we do it??

Is there any economy of scale? Why not wait until the first one fails to build another one?

Because that requires keeping all the specialized machinery and knowledge alive for the duration of the whole project.

Given the length of this project, I wouldn't be surprised if at this point NASA couldn't order a second one built even if they wanted to.

The unfortunate thing about advanced technology is that if you don't use it, you lose it. More specifically, you lose the research and machining setups and people with knowledge about them in their head; the main problem here being that documentation doesn't capture everything - a lot of tacit knowledge is captured in e.g. tuning of the machines, undocumented fixes made on-site, idiosyncrasies in manufacturing steps, etc.

Re: James Webb Space Telescope emerges successfully from final thermal vacuum test

#73

Post by sanxiyn »

java-man wrote: post #27

what puzzles me all the time is why not build two instead. it looks like the R&D portion of the budget might be greater than the actual manufacturing cost, so building two would be less than 2x the price. if one launch fails, we've got a backup. if both launch, we have two instruments deployed. why don't we do it??

NASA sometimes does it. Mars 2020 is an upgrade of Mars Science Laboratory (aka Curiosity) spare.

Re: James Webb Space Telescope emerges successfully from final thermal vacuum test

#74

Post by teraflop »

NikolaeVarius wrote: post #7

Man, I really want this telescope to succeed its mission, but I just can't get over how complex its deployment procedure is. I am extremely pessimistic about it actually managing to deploy as planned.

That's what I thought about Curiosity's skycrane, and that ended up working out pretty well.

Yes, it's complicated, but I'm willing to accept that my intuitions about whether something is too complicated are wrong when we're talking about something that actual rocket scientist have spent millions of hours planning.

Re: James Webb Space Telescope emerges successfully from final thermal vacuum test

#75

Post by CydeWeys »

rakoo wrote: post #56
Klathmon wrote: post #32

Earlier quoted context omitted.

To be a bit more specific, we can't send something up to fix this because it's magnitudes further away from the earth than Hubble is. JWT will be ~1.5 million km away from earth, in a special orbit around a spot called the "L2 Lagrange point". It's located there so that it can kind of hide in the earth's shadow at pretty much all times and keep all the nearby "bright" things behind the heat shield. For comparison, th…

Minor nitpick, but the L2 point is selected so it doesn't need fuel to stay there. It's like a gravity well of the earth/sun system, any object getting a little further from it will get back to it.

L2 is unstable. There are stable Lagrange points that would be much better for this purpose if that was the reason.

The unique thing about L2 is that it's the only Lagrange point where the Sun is always blocked by the Earth. That's what they're going for here.

Re: James Webb Space Telescope emerges successfully from final thermal vacuum test

#76

Post by jjoonathan »

NikolaeVarius wrote: post #45
Klathmon wrote: post #32

Earlier quoted context omitted.

To be a bit more specific, we can't send something up to fix this because it's magnitudes further away from the earth than Hubble is. JWT will be ~1.5 million km away from earth, in a special orbit around a spot called the "L2 Lagrange point". It's located there so that it can kind of hide in the earth's shadow at pretty much all times and keep all the nearby "bright" things behind the heat shield. For comparison, th…

We also can't fix this, because it was designed to be unfixable. Making it fixable would counter productively make the design more complex.

With a $10 billion telescope dead in the water and the clock ticking, Louis Rossman leads a crack team of Apple repairmen -- specialists in fixing sytems designed to be unfixable -- through accelerated astronaut training for a last-chance human mission to L2! Will they save the day? Or will the inky clutches of space doom the mission and leave them stranded farther from civilization than any human in history?

Re: James Webb Space Telescope emerges successfully from final thermal vacuum test

#77

Post by dylan604 »

java-man wrote: post #27

what puzzles me all the time is why not build two instead. it looks like the R&D portion of the budget might be greater than the actual manufacturing cost, so building two would be less than 2x the price. if one launch fails, we've got a backup. if both launch, we have two instruments deployed. why don't we do it??

“The first rule of government spending is build two at twice the price” — S. R. Hadden

Re: James Webb Space Telescope emerges successfully from final thermal vacuum test

#78

Post by skizm »

jcadam wrote: post #37
skizm wrote: post #34

Anyone know if there are any well paying jobs in space programs of any kind? I've been seeing a growing number of reputable universities offering a wider range of space / aerospace / engineering offerings* and I've been getting curious what's out there. Only issue is, a lot of places I looked pay well below market rates :/ (at least for software engineers). I'll admit my expectations might be off considering I've bee…

Just a bit of warning: Software Engineering in Aerospace is NOT fun. You're basically in a supporting role to the hardware and system engineers designing the spacecraft. It's pure drudgery... process to the point of absurdity, specs and tasks being spoon fed to you with little room for creativity and/or problem solving, etc. The pay, benefits, and level of respect on the job reflect all of that. If you really want to…

Thanks for your insight. I was actually eyeing the "space systems engineering" degrees. If I did ever make a move I'd probably want to transition from the individual contributor software engineer to something higher level (like you say, systems level). Space seems super interesting from the outside looking in, but I supposed there is a lot of careful work involved given the higher stakes, which makes the process much slower than most software companies.

Probably won't actually make the switch, but just interested in seeing what's out there I guess.

Re: James Webb Space Telescope emerges successfully from final thermal vacuum test

#79

Post by RosanaAnaDana »

jjoonathan wrote: post #76
NikolaeVarius wrote: post #45

Earlier quoted context omitted.

We also can't fix this, because it was designed to be unfixable. Making it fixable would counter productively make the design more complex.

With a $10 billion telescope dead in the water and the clock ticking, Louis Rossman leads a crack team of Apple repairmen -- specialists in fixing sytems designed to be unfixable -- through accelerated astronaut training for a last-chance human mission to L2! Will they save the day? Or will the inky clutches of space doom the mission and leave them stranded farther from civilization than any human in history?

Elon Musk spots them a SpaceX rocket. Joe Rogan puts them through basic training.

I'd watch this youtube red series

Re: James Webb Space Telescope emerges successfully from final thermal vacuum test

#80

Post by hhh »

jjoonathan wrote: post #76
NikolaeVarius wrote: post #45

Earlier quoted context omitted.

We also can't fix this, because it was designed to be unfixable. Making it fixable would counter productively make the design more complex.

With a $10 billion telescope dead in the water and the clock ticking, Louis Rossman leads a crack team of Apple repairmen -- specialists in fixing sytems designed to be unfixable -- through accelerated astronaut training for a last-chance human mission to L2! Will they save the day? Or will the inky clutches of space doom the mission and leave them stranded farther from civilization than any human in history?

Can't wait for the theater version, starring Louis Rossman!
Post reply on HN