The James Webb Space Telescope has only gone and deployed its primary mirror The gold-coated primary mirror of the James Webb Space Telescope (JWST) was fully deployed this weekend, marking the end of the epic major deployments of the spacecraft, but only the beginning of months of alignment and calibration. The deployment of the sunshield required to keep things cool was successfully completed last …
The thing about space, the colour of space, is that it's black.
A camera on the "hot" side of the spacecraft would only see the bus, radiator, solar panel and high gain antenna. Boring!
A camera on the "cold" side where the mirror is, wouldn't see anything at all. Because it's dark.
The cold side is intentionally designed to be completely and utterly dark. No lights at all, and there's nothing to scatter any light. Just imagine how horrific it would be if a light got stuck on and ruined all observations!
"Could a separate camera "drone" be deployed to watch these things"
Well, it could...but it would need to provide it's own lighting, as the main part of the WEBB is in shadow (and hence darkness) and is facing away from the Sun.
The WEBB is also beyond the orbit of the Moon too, so any reflected light from there would not help.
The other issue of course is "adding complexity" as this drone would need a comms link to the WEBB and then any video signal would need to be piggy-backed onto the various other telemetry signals being sent back to MOC...and given that WEBB is travelling at abt 1000 mph, large packets of data are more prone to "interference".
And then there is the question of controlling the drone so that the "video director" can bring the WEBB into focus and be watching the "required" section of the Telescope.
And the drone camera would be operating at around -300 deg F...
Of course given the $10BN cost of the WEBB, adding such "extras" probably wouldn't add much cost - but given it would be used for maybe a few minutes each day (to hopefully observe such deployments), I doubt it was high up on the "original" specifications list.
"Voyager managed to take detailed pictures of Jupiter, Saturn etc back in 1970s and 80s, pretty sure tech has moved on a bit?"
Indeed it has...but getting a video camera (and the connected hardware) to work at very low temps requires small heater elements to bring them up to operating temps, and that requires power from very well insulated batteries, or some nifty solar panels. This all adds expense and for what? a few minutes of live video feed?
"Plus we see live images from outside all sorts of rockets, capsules etc."
Many video images are either from within the atmosphere (such as launch and/or recovery of a SpaceX 1st stage) and so they are at "normal" temps to begin with - or maybe a camera might be fitted to other "space hardware" that is beyond Earth atmosphere and such hardware has a source of power to keep the camera warm (from the "coldness" of space).
At the end of the day, decent telemetry and a nice "virtual" graphics display is more useful (for public consumption and "wow" factor(s), than a solitary video feed from a drone that costs a fortune to design/build/utilise and then is "cast aside" once the various deployments are completed.
And then there's the question of what happens to the drone afterwards? It could "fail" at some point and damage the WEBB or you might just point it at some star and send it off....maybe using a small ion drive?
In the case of voyager 1 & 2, it's nuclear batteries that keeps them warm. The decay half-life giving off heat. It's also why they're barely working now. Not because the equipment failed but because there's just not enough power being given off anymore to keep all systems going. Especially considering how much juice is needed to run the antenna on the crafts.
If you have a drone then it has engines. If that drone can ever be on the dark (working) side of JWST then those engines are running on that side of JWST. And they are spitting out exhaust, probably rather hot exhaust. Which will now be close to a very very cold, very very expensive mirror and other optical systems. If the exhaust condenses on the mirror you can not ever get it off and suddenly your $10bn telescope can not see very well. Exhaust probably also includes nice corrosive things like ammonia and some unburned hydrazine at least if they are hydrazine monoprop engines which probably they will be. Very nice to have such things impinging on your expensive telescope.
This is the reason JWST has no engines at all on its cold side: really, really do not want engine exhaust anywhere near it.
And all this assumes drone works perfectly. What if it does not? what if it hits the telescope? Now you have $10bn of junk instead of a telescope and you will never, ever get another chance to build one.
So no drones, no cameras: minimise risk maximise science.
"Why no cameras to watch the deployment of the multi-billion dollar observatory?"
Simple: When was this device designed? It started in 1996. What was the state of space rated video cameras then? They were all built for space probes - there were no space rated cameras to get you the video you wanted at the time.
And there was no way anyone was going to delay the schedule (Spend money) again just to beam glamor shots.
Add to this the added complexity, thus the increased risk for the telescope, the weight, the unexpected side effects in the long run... Having a camera just to watch the unfolding wasn't worth the effort.
Let's us Europeans self-congratulate. Ariane 5 made such an outstanding job that enough fuel can be kept to extend JWST life
Also the goPro pictures from SpaceX boosters are a lot closer to Earth.
Getting video back from a 1st stage booster dropping from a few km is a lot easier than getting video back from something heading past the moon.
And the pictures would look less 'real' than the simulations of stuff unfolding anyway - there is nowhere you can put a camera for anything except the mirror unfolding and that would mostly be in shadow.
A camera would be nothing be PR. Sensors on the craft can do a better job of verifying elements are in place than a camera could. If the platform couldn't fully deploy, having a camera onboard to see why something is hung up may do nothing towards solving the problem. I expect that if the whole thing was Tango Uniform, some space asset might be tasked with taking photos to figure out why even if they couldn't be shared just to find out why $10bn worth of kit was a complete write off.
As far as using a spy sat to take photos, they only have so much fuel on board so turning around the other way and then turning back would eat up a whole bunch of their mission capacity. Some of those birds might cost an equivalent amount of money. Fat chance the public will ever be told what the price tag is for those toys. They can divulge whatever figure they like and there is no way to check.
NASA excels in building kit that works and lasts. That's one of the reasons we won't see pictures for over a month.
During that time, NASA will individually test each one of the over 100 actuators that move the mirror segments. Then they will begin the process of aligning the primary and secondary mirrors using the actuators.
Slow and steady wins the race. Go boffins.
NASA has learnt from the initial imaging problem of the HST by having each of the hexagon sub mirrors fo the main array individually controlled for set up.
"When the engineers need to adjust the positions and shapes of the mirror segments to achieve precise alignment, they use the seven actuators (tiny mechanical motors) attached to the back of each one of the mirror segments."
from:
https://www.nasa.gov/feature/goddard/2017/aligning-the-primary-mirror-segments-of-nasa-s-james-webb-space-telescope-with-light
Here's hoping it all still works in the vast blackness of space.
It's the only way to pack a 6.5m mirror into what was supposed to launch on a Delta4.
Above about 8m diameter it's tricky to make a single monolithic mirror so we've been building segmented ones since the early 90s.
The main problem with segmented mirrors at these IR wavelengths isn't aligning them - it's that you can see the glowing hot telescope floor through the gaps. Which is solved by putting it in space and keeping it very very cold.
The real achievement was doing the OSHA paperwork to get the Beryllium mirrors polished in California!
It is fact top notch. NASA has just announced that the Ariane 5 team did such a splendidly precise launch/deploy that the amount of its onboard fuel that the JWST will need to use on final adjustments has been drastically reduced. This in turn has doubled the likely lifetime of the telescope. They had initially calculated on a ten year mission - they are now talking about 20 years!
for there can now be no "low" in it's opening or it's orbit. It a Lissajous orbit following an approximately circular path, and the eccentricities of it a clever piece of math designed to minimize the costs of station keeping on an otherwise slightly unstable L point.
But let's face it, everyone is going to call it a halo orbit because good luck getting past autocorrect and it's angry red line and still ending up with "Lissajous" and not "Lisa is jealous" or some similar howler.
Nitpickery aside I am overjoyed that the JWST is this far along. I was afraid to watch the earlier stages lest I have to witness what would have been a truly heartbreaking failure. Still got my fingers crossed, but my anxiety level is way down during what will be a bit of a wait till the official 1st light photo comes in.
Any bets on where that will pointed at? Has it been declared yet?
No idea where it will be pointed first, but, just like Hubble, I expect they will eventually try 'an empty piece of sky' and see what they find.
"In 1995, astronomer Bob Williams wanted to point the Hubble Space Telescope at a patch of sky filled with absolutely nothing remarkable. For 100 hours."
https://www.nationalgeographic.com/science/article/when-hubble-stared-at-nothing-for-100-hours
The possessive apostrophe ("Fred's orbit", "it's mirror") is a legitimate and historically correct English grammar. Style guides may specify "its mirror", but that's style, not grammar.
Possibly more common in the USA (as I recall, possessive "it's" was used in the declaration of independence), but the USA often retains different original forms that the UK does.
The posting does contain grammatical / spelling mistakes (as may this one), and computer 'grammar' guides are also characteristically style guides as well, but "it's" is a bad choice of example.
The possessive apostrophe ("Fred's orbit", "it's mirror") is a legitimate and historically correct English grammar. Style guides may specify "its mirror", but that's style, not grammar.Possibly more common in the USA (as I recall, possessive "it's" was used in the declaration of independence), but the USA often retains different original forms that the UK does.
Do you have evidence for this? I mean for possessive '*it's' in historical use? Certainly is not the case for declaration of independence and I have never heard of it historically being true but rather that 'its' is correct because 'his' / 'hers' etc. But I am not native English speaker.
Because, contrary to UK councils deploying an ERP, NASA knows exactly what needs to be done, has recorded the milestones and is applying said knowledge to ensure that JWST will be functional.
I suggest that all UK councils wanting to deploy an ERP go take a learning course in project management at NASA.
They will utterly fail, but at least they will get a cluebat to the face.
To be fair though, this is only doing the world's biggest origami project at a few degrees above absolute zero a million miles away.
Compared to the insurmountable difficulties of capturing the requirements of a poll tax billing system for East Sussex compared to West Sussex....
I follow the JWST twitter account, and in response to to today's successful test of all the mirror segment motors (amazing to me that these motors work at -200C, my internal actuators barely function at 20C) and despite the patient, detailed explanation linked to in this article, there are STILL idiots ranting nastily about the absence of video footage, including this gem "how are you going to inspire kids if you don't show them?" My post title is, of course, an allusion to one of the 4,356,743,212 things ALLEGED to have been said by Einstein but whoever said it, they was right.
A. Does anyone remember the oxygen consumption of Apollo 14? What is the current main data transmission rate of Voyager 1? Can anyone imagine the shape of dust storms on Mars?
B. Does anyone remember Neil Armstrong climbing down the ladder onto the Moon? Have you ever witnessed a total solar eclipse? Have you ever witnessed a launch of the space shuttle?
Which excites you the most, A or B? PR is everything. Unfortunately scientists and engineers don’t really understand that. Science does not speak for itself. If the JWST didn’t have cameras, then put them on. Figure it out; it’s NASA. Hire an advertising firm. They did it for Apollo 11 which also didn’t need the additional complexity.
And this is what Musk, Bezos and Branson understand. This is why the Millau Viaduct is widely known as having been built by Norman Foster. This is why was Trump, and why he could serve another two terms.
I respectfully yet forcefully suggest that all science and engineering courses should include marketing components. Otherwise we’re all going to end up like Nebraska.
The Register 
Biting the hand that feeds IT
Copyright. All rights reserved © 1998–2024
