JWST launch delayed to 2019

[67Dino]

IAmTheWalrus said:

LostM135idriver said:

Have to get the detectors all cooled for a start.

I guess there is probably a certain amount of degassing/out gassing from all of the components that will also happen. I imagine quite a lot of care is taken to make sure nothing is deposited in the pathlength of the instrument or detectors.

Also got to get the tripod all set up level and polar align the telescope too I suppose.

I assumed this would all be automated seeing its in space...

Waiting to cool cannot be rushed! Also, each one of the 18 hexagonal gold mirrors is motorised for orientation. So they all need lining up to each other within a crazy level of tolerance. Must be like 3 dimensional chess.

[LostM135idriver]

IAmTheWalrus said:

LostM135idriver said:

Have to get the detectors all cooled for a start.

I guess there is probably a certain amount of degassing/out gassing from all of the components that will also happen. I imagine quite a lot of care is taken to make sure nothing is deposited in the pathlength of the instrument or detectors.

Also got to get the tripod all set up level and polar align the telescope too I suppose.

I assumed this would all be automated seeing its in space...

(One of, I think) The detectors are actively cooled using a (i think) helium cryopump, so that it’s more sensitive. Partly that’s about reducing noise, but also because the telescope is detecting infra red light you want all of the components in the light path to be as cold as possible, or the heat emitted by them will swamp the signals you are trying to detect.

[andy_s]

Are there any more critical failure points now - it looks good to me barring the commissioning & tuning stages?

[LostM135idriver]

andy_s said:

Are there any more critical failure points now - it looks good to me barring the commissioning & tuning stages?

Aliens maybe

[MartG]

andy_s said:

Are there any more critical failure points now

The insertion burn into its final orbit around L2

[2fast748]

andy_s said:

Are there any more critical failure points now - it looks good to me barring the commissioning & tuning stages?

I read somewhere there are still 49 points of failure still in the duration of the mission (est. 20 years now) but all of these are things that would happen to anything put into space and not unique to JWST, such as propellant tanks exploding!

The next MCC Burn is only a small one apparantly, so not too much of a concern.

[andy_s]

Good to hear

[Mr Whippy]

I’ve not looked, but what are the current best IR deep field images like?

I’m assuming we know there is lots there to see, but it’s just blobs and splodges?


Is what we’ll be getting half-way to CBR, so a bit more of a high detailed map of the early universe?


It makes me think about a Roger Penrose interview where he discusses time and distance being irrelevant at the death of the universe, as entropy reaches its peak, could that actually be the starting point of a new phase of expansion (ie, the big bang)

What kind of information about the universe is hiding off in the distance.

I know I’ve got a short attention span but to invest the best part of half your career into a project like this, that can just fail over, it’s an amazing level of dedication… it must be an awesome feeling working on this stuff and it getting its first data!

[Roofless Toothless]

First picture in of the start of the universe.

[Eric Mc]

Mr Whippy said:

I’ve not looked, but what are the current best IR deep field images like?

I’m assuming we know there is lots there to see, but it’s just blobs and splodges?


I

Hubble can do infra red imaging. Here are some examples with visual wavelength images for comparison -

[MartG]

[MiseryStreak]

Mr Whippy said:

I’ve not looked, but what are the current best IR deep field images like?

I’m assuming we know there is lots there to see, but it’s just blobs and splodges?


Is what we’ll be getting half-way to CBR, so a bit more of a high detailed map of the early universe?


It makes me think about a Roger Penrose interview where he discusses time and distance being irrelevant at the death of the universe, as entropy reaches its peak, could that actually be the starting point of a new phase of expansion (ie, the big bang)

What kind of information about the universe is hiding off in the distance.

I know I’ve got a short attention span but to invest the best part of half your career into a project like this, that can just fail over, it’s an amazing level of dedication… it must be an awesome feeling working on this stuff and it getting its first data!

I read (here: https://www.vox.com/science-and-health/22664709/ja... ) that the JWST is 100 times as powerful as the Hubble. Not sure exactly what that attention grabbing headline is referencing, probably nonsense, and they’re not directly comparable anyway due to the wavelengths they are collecting.

But this article gives a detailed comparison and a diagram for how far back Webb will look:

https://www.jwst.nasa.gov/content/about/comparison...



250 million years after the Big Bang, at the very first light to emerge from the first proto-stars. Hubble could only see back to 400MY after.

It will also be able to directly image nearby exoplanets and get an idea of their atmospheric composition. Atmospheric oxygen probably means life, it certainly wasn’t on Earth until Cyanobacteria starting releasing it, so evidence of that will be very exciting.

[Russ35]

Some info and pics of the MIRI filter wheel on twitter

https://twitter.com/mpi_astro/status/1481379175709...

and some movies of it being tested.


https://owncloud.gwdg.de/index.php/s/heshCTJSfwb7f...

[MiseryStreak]

95% distance to L2 travelled (5/30 days to go):

https://www.jwst.nasa.gov/content/webbLaunch/where...

[SpudLink]

MiseryStreak said:

95% distance to L2 travelled (5/30 days to go):

https://www.jwst.nasa.gov/content/webbLaunch/where...

And then it takes three months (!!) to align the mirrors.

[Beati Dogu]

The JWST will arrive at its destination today. It’ll be around 1 million miles from Earth. It’ll fire it’s thrusters to put it in the correct orbit later on.

NASA will have press conference about it from 8 pm UK time.

https://www.nasa.gov/press-release/nasa-to-discuss...

[ChocolateFrog]

I didn't realise that it's actually only doing about 450mph now. I guess I thought it would be doing a lot more.

7000km to go according to the tracker.

[SpudLink]

ChocolateFrog said:

I didn't realise that it's actually only doing about 450mph now. I guess I thought it would be doing a lot more.

7000km to go according to the tracker.

As far as possible they would use gravity for deceleration, rather than burning fuel.

[_Yeti]

Scott Manley described it as rolling something up a hill with the intention of it stopping by itself at the top.

[Krikkit]

Imagine rolling a ball up a slide and having it stop perfectly on the seat, that's effectively what you're doing.

You'd need to judge the speed perfectly, and as it rolled up the hill it would slow quite dramatically.