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James Webb Space Telescope emerges successfully from final thermal vacuum test

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

#131

Post by ttul »

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.

Indeed. The NRO - rumor has it - has been launching satellites to observe the earth in the infrared for years..

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

#132

Post by CharlesColeman »

JudgeWapner wrote: post #82
mdorazio wrote: post #38

Earlier quoted context omitted.

To be fair, the reason for this is that if you try to be creative and don't follow strict processes, things fail a million miles from Earth or blow up entirely.

You mean the strict processes that strictly demanded mixing imperial and SI units ?

> You mean the strict processes that strictly demanded mixing imperial and SI units ?

You're describing a mistake that happened literally 20 years ago. Don't you think they might have changed the processes in all that time?

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

#133

Post by petschge »

ATsch wrote: post #129
petschge wrote: post #120

Earlier quoted context omitted.

This requires keeping the baseline constant to a fraction of the wave length. In other words you would have to position the satellites with a accuracy of 100 nm relative to each other. In other words: No we can not (, yet. For a decade at least).

wasn't there an experiment that used laser interferometry to calculate the precise distances between a constellation of three satellites? I assume something like that could work?

That was the LISA Pathfinder mission (https://en.wikipedia.org/wiki/LISA_Pathfinder), the preparatory step for a gravitational wave detector in space. And yes something like that could work eventually. Right now we are doing science on that concept. It takes a decade or three to get the technology mature enough that you can do astronomy with it.

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

#134

Post by petschge »

ttul wrote: post #131
gnu8 wrote: post #36

Earlier quoted context omitted.

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.

Indeed. The NRO - rumor has it - has been launching satellites to observe the earth in the infrared for years..

Since you are looking at a warm planet you will never get your camera down to 7 K nor do you need to as all sources are close by and bright compared to the astronomical targets for JWST. So the shielding issue is somewhat different. Having Earth, Moon and Sun in the same direction so you can block all of them with a single heat shield is actually one of the reasons why JWST is going to the L2 Lagrange point.

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

#135

Post by baq »

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.

A more complicated process has worked multiple times in orbit already, look up the Orion program and Mentor sats.

https://en.m.wikipedia.org/wiki/Orion_(satellite)

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

#136

Post by GlenTheMachine »

Damorian wrote: post #51
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 adding on to this. The government funded research labs and DoD contractors I've had offers from have been seriously sad, which makes me concerned on the quality of their missions, personally. Also it's frustrating because I'd much rather work in that space. I'm a senior dev making ~140k and was just offered 80k in a higher cost of living to manage a team of 10 developers with TS clearance working on spy satellit…

That's definitely a lowball offer.

Government research labs are on the GS scale (mostly). We're capped at $166,500/year in the DC/NY/SF area (and also, as it happens, the Denver area). $80k is what we offer fresh-outs. A senior flight software engineer managing ten developers with a TS should be near if not at the top end of the salary range.

Contractors doing that work should be similar or higher. I've tried to convert contractor senior flight software engineers to civil servants, and I couldn't... because our ~$150k/year offer was $30k/year too low.

Here are the GS pay scale tables. The job you've describes should be either a high GS-14 or GS-15. So, $133k/year and up.

https://www.opm.gov/policy-data-oversight/pay-leave/salaries...

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

#137

Post by petschge »

jandrese wrote: post #126
gootdude wrote: post #115

Earlier quoted context omitted.

The mission is minimum of 5 years with maximum 10 years based on the fuel. https://jwst.nasa.gov/faq.html#howlong

After 10 years it will probably need more than just fuel. And doing maintenance in orbit, especially way out in the L2 point is easier said than done. Probably easier to build a new satellite with even more capability to replace it, except of course that the JWT is famously behind schedule and over budget and a more sophisticated replacement probably won't be any easier to build.

A replacement might actually easier to build. The detector is no small feat, but the major problems with JWST come from the foldable heat shield and the segmented mirror. Both of which are due to size constraints during launch. Basically it has to fit a 20 x 14 m heat shield and a 6.5 m mirror into the 6.4 by 4.6 m fairing of an Arianne 5.

Targeting a rocket with a larger fairing diameter (even at same payload mass) would make the design much simpler. An upper stage with 20 m length and 9 m diameter on a Falcon Super Heavy would allow to have a fixed mirror and heat shield that is only folded once, instead of the crazy origami that JWST is. But of course such an upper stage doesn't exist yet. SpaceX was only started 6 years after the work on JWST started...

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

#138

Post by sigstoat »

anchpop wrote: post #118
sigstoat wrote: post #104

Earlier quoted context omitted.

> There are many examples of NASA missions that had far exceeded the original expectations. many of those concocted by NASA announcing artificially low public expectations, while ensuring the contractors know what the real (much higher) expectations are.

Citation?

the whole point is that NASA isn't documenting this. go get a job in the industry and ask around after a couple of years.

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

#139

Post by jvanderbot »

GlenTheMachine wrote: post #110
ethbro wrote: post #103

Earlier quoted context omitted.

"What do we do when the robotic satellite fails?" "Send another robot!"

https://sspd.gsfc.nasa.gov/restore-L.html also https://www.darpa.mil/program/robotic-servicing-of-geosynchr...

Thank you. I was hoping to post these!

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

#140

Post by velosol »

Damorian wrote: post #51
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 adding on to this. The government funded research labs and DoD contractors I've had offers from have been seriously sad, which makes me concerned on the quality of their missions, personally. Also it's frustrating because I'd much rather work in that space. I'm a senior dev making ~140k and was just offered 80k in a higher cost of living to manage a team of 10 developers with TS clearance working on spy satellit…

If it was direct government employment did they clarify final salary? There's the 'salary' and then the locality increase [1] which is a base of around 15% and goes up to 28% for places like DC. 102k (1.28*80) is still not worth it especially without prior federal service as you have pension vesting etc to wait for before your benefits are worthwhile.

[1]: https://www.opm.gov/policy-data-oversight/pay-leave/salaries...

Fixed math.

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