One of the taller people in there is 6'4. :)
Here's one with a human for scale standing near the mirror,
With the folded assembly,
The JWST going in for testing,
With the sun-shield unfurled,
Putting this instrument operational at the right place is probably an unprecedented mission in terms of automated complexity.
I definitely don't want the JWST to fail. I've never seen an image which endears such an existential crisis as the hubble deep field.
I simply, paradoxically, wonder what good might come if this does fail.
Sure some of the money went to R&D but the question is not can be it be used on a future telescope, it's will it be used?
I suspect if someone wants to launch another telescope today they would look at JWST and largely say they need to start over because it doesn't make sense to start with a 20-year-old design.
Take the sunshield - the huge tarp-looking thing that you always see below the telescope itself. My understanding is that this is critical for JWST to see in the deep infrared, since otherwise heat will interfere with the imaging. Probably a lot of money was spent on the development of this. But if that money had just been spent on 20 other telescopes, none of them would have been able to capture that part of the infrared spectrum that JWST will.
The power limit also requires that science data be downloaded with an experimental 26Ghz radio that only the three 100' diameter Deep Space Network dishes can receive. The projected science data download will require using the DSN for 8 hours a day, everyday for 5-10 years.
They should have started over using nuclear power and then they would have had a chance.
At the low temperatures involved, Earth's night side puts out enough infrared radiation from its own heat to cause problems. JWST is all the way out at Sun-Earth L2 not for power reasons, but so that it will never be in a position where it needs to keep off heat from two different directions.
Nuclear does not help with this. In fact, by having a nearby penetrating radiation source and a high-temperature core mechanically connected to the spacecraft, it may be worse from a thermal perspective.
JWST is a strange spacecraft with very strange design constraints. Your intuitions about planetary/Earth-science or higher-frequency astronomy will not serve you well here.
Here is a good place to start:
Yes, insulating an RTG from the IR sensors would have been a challenge, but one that could be completely and accurately tested on earth. The lack of sufficient power directly drove the passive cooling requirement. Which in turn drove the fraught 5 layer shield requirement - which has never been and can't be "Test as you fly" tested on earth.
The lack of power also drove the decision to use the experimental 26 Ghz Ka band downlink radio instead of a higher power and more robust X band radio.
My calculations tell me this is not true for Mars though. The next time we do this, we should send it to the L2 of Mars.
There is a broader point about space exploration in general here. The science that can be delivered by nuclear powered probes is well beyond that of solar ones. Higher instrument power, better comms, longer life, more predictable power supply. It's just better. There's one place in America that makes the plutonium for RTGs.
Plutonium is the ideal RTG fuel from an engineering point of view. But controlling and securing it jacks up the costs. What we need is lots of research into less-politically-fraught fuels. Americium is looking really promising.
(Of course the "dark side" isn't actually dark when the Sun hits it, so that would limit the available observing time.)
Edit: I just realized this idea comes from radio telescopes. Those would actually benefit from sitting on the far side of the moon, because that way they'd be shielded from the radio emissions of human civilization. That concept doesn't transfer to visible light or IR telescopes though.
The Earth might as well be as big as the Sun from the perspective of the IR instrumentation on JWT. They'd prefer to keep it entirely out of their field of view, which is why it's being positioned at L2. Placing the telescope on the far side of the moon would have the same effect at least part of the time, and we'd potentially be able to carry out maintenance and upgrades in the future.
I don't think there's any place in the solar system you can put things so that they won't be in the sun. If you're going to be in the sun anyway, better use it.
However in regards to JWT I expect that a lot of its missions will collect miniscule amounts of light, making interferometry infeasible.
Other uses include debugging already-launched kit with the easily accessible copy, reusing in other projects, and ultimately, museum artifacts.
It is also worth saying that producing anything, from mirrors and cameras, to boring screws and nuts, that end up going into space, is no small endeavour. It's not the case that you can just mill something out of aluminium, then do it N more times. Here's a nice video about it: https://www.youtube.com/watch?v=QlASewYMDsg (in fact in the specific context of JWST)
Nope. This is a generational project. At all levels, but more so at the top, the people involved have spent significant blocks of their working lives on this project. Many have begun and ended decade-spanning carriers totally within this one program. It has taken so long that few will be around to contribute to the next. The institutional knowledge will have all retired or moved on by the time we are ready to fund the next epic telescope.
This problem has parallels other programs such as the F-35. Nobody lives/works long enough to see the project from beginning to end. Everyone at the start moves on/up/out. Those present at the end joined in the middle after major decisions were already set in stone. Priorities shift. Deadlines measured in decades start to seem unreal. Everything slips into bloat and delay because so few expect to still be around on D-day. It's a problem with no good solution.
This has only been done a handful of times outside of Kerbal. Apollo was one of the very few times that two spacecraft launched separately and then continued onto another orbit (as opposed to space stations that are built and stay where they are). Connecting two objects and then blasting them into a transfer orbit ... even Apollo didn't do that. I don't think it has ever been done. It would mean strong docking hardware and deep structural analysis to handle flexing while under even moderate thrust, something far more than aligning a couple docking ports.
Getting a delicate craft to escape velocity would require multiple burns over multiple orbits, necessitating engines that could relight many times. Electric drives could work, but they lack the thrust for a final definitive escape towards an L point.
If only building a large, pressurised hangar in space was easy!
How much better would the program run overall if it were comprised of a series of increasing-stakes missions, like Apollo? Build a dummy instrument just to test the heat shield. Send a satellite up to L2 with no optics just to test the 26Ghz link. Heck, even just one "dress rehearsal" launch and deployment would inform so much.
> Hadden : First rule in government spending: why build one when you can have two at twice the price?
"It's 10-100x more difficult to design the production system than the engine itself"
So what we really need is to invest and innovate in the production of complex telescopes/probes/etc such that it doesn't cost $10 Billion and 20 years to build, and the loss of one wouldn't hinder the overall production.
What we really need is to standardize as much of the telescope as possible.
Communications? Don't need to be bespoke per satellite.
Guidance/Navigation? Doesn't need to be bespoke.
Ultimately only the actual optical payload really needs to be bespoke. Commonality of components and design can drive down prices and reduce time-to-launch.
people who don't care about pointing accuracy end up spending zillions of dollars so they can have fraction of an arc-second precision
satellites that are in Earth orbit have different thermal needs than one in L2
satellites that are less weight sensitive waste money on carbon fiber
an instrument that needs to be cooled down to 50K doesn't need a JWST-tier cryocooler, etc.
You could try having a range of things, e.g. small, medium, and large bus with a handful of interchangeable subsystems. But you're still asking designers to sacrifice their precious size, weight & power requirements
1. Forensics difficulty. You need extensive data to debug issues for complex systems. You can collect so much more data from terrestrial testing, which allows you to do the extensive forensic analysis required to achieve the required component reliability. Once you put a telescope in space, you can't inspect it anymore. A lot of the sensitive components which might fail on JWST have to be inspected to microscopic precision in order to perform adequate failure analysis.
2. Design requirements are far, far more precise. Many failures in deep space are effectively impossible to correct in later iterations due to point 1. Telemetry and sensor data is enough to debug rockets, but for JWST you would need to ship so much extra data/sensor infrastructure alongside the telescope that the whole project becomes recursively intractable.
The system complexity is so high that you absolutely must have the ability to make arbitrary system corrections because the chance of "building everything correctly the first time" is effectively zero, even with perfect hindsight! Essentially, any time you build the thing from scratch, you will always find mission-ending statistical deviations. The objective of on-ground testing is to identify and correct those specific deviations, until the whole system is within design tolerances. If you were to totally rebuild it, the next iteration will have a totally different set of statistical deviations which will need to be corrected. This process of development involves "hardening" the entire system through extensive testing, because it impossible to build a fully-hardened system to start with, even after "learning" from previous attempts.
Kind of like in computing, where we moved from a single ultra reliable mainframe to tens of commodity hardware.
Commercial software development practices might be relevant where you can fix things overnight, but this is hard science instrumentation made of atoms, you ship things that must work as expected because the whole point of all this is making better measurements as the field evolves and there's a scientific case for doing it. It is not about selling production versions of the experiment to potential customers.
Instead of sending up 1 super precise super accurate super reliable telescope let's send up 1000 mostly POS telescopes and combine the results using AI of the 900 which actually make it to orbit and return useful images.
I'm hardly saying that's a 100% working plan, but, I think that kind of paradigm shift which is required.
It's not like space telescopes need any of the valuable orbit space, and even if they did it's easy to put thrusters on board that can de-orbit them or move them to a graveyard orbit (depending on their operational orbit) in the case of failure.
To summarize, you have to have the ability to correct statistical aberrations after manufacture via extensive validation and testing, as opposed to design aberrations which can largely be eliminated through destructive iteration. Without the former process, you'll launch a million telescopes and not a single one will work.
Remember that Hubble was essentially useless until heroically repaired the first time by Story Musgrave. Many subsequent repairs were required to get the best pictures from it - like the deep field, long duration picture.
If each of these had a high-grade commercial camera lens pointed towards earth, you could have real-time viewing of the entire planet with just a little bit of math. With a bit more fun (and for each click of optics improvements), you could "Bullet Time" view a great number of things...
If each of these had a high-grade commercial lens pointing outwards, what could that be used to capture? At scale, it seems like doing diff's against all the images would reveal a huge number of previously unidentified asteroids and other near-earth objects.
What if you put "very good" optics on them? Or a radio antenna pointed out? Could you make earth sized optical or radio telescopes? Seems like you could.
It's increasingly looking like the assumption each one needs to drive the state of the art, and each one needs to be "space grade at 100x the cost" is a fallacy simply because launching was historically so expensive.
With asteroids, you don't need to diff telescopes at different locations; you can just diff the image taken at one location, 15 minutes apart.
This should have been cancelled 3 or 4 years ago when the sunk costs were only $8B. Instead we dumped another $2B into this almost sure failure
Nothing, to me, indicates "almost sure failure." Just a realistic overview of the risks.
To name a couple other problem spots:
They have trouble getting the shield to deploy on earth:
The IR detectors were replaced in 2015 because they were deteriorating in storge. Now the new detectors are 6 years old:
Even the 26Ghz downlink radio that can only be received the the 3 huge Deep Space Network dishes on earth is an experiment.
I really REALLY want the Webb to work, but I would take 10:1 action against.
You will pay me $250 if NIRCam returns one scientifically useful observation (i.e. photograph). I will pay you $25 if it does not. If the only observations are of debatable scientific value (e.g. somewhat blurry), then the wager is off.
There are three analogous wagers for NIRSpec, for MIRI, and for NIRISS (for a total of $1000/$100).
The deadline is when all four wagers are resolved in my favor, or when it is obvious that they will be resolved in your favor (i.e. loss of vehicle), or December 31st, 2023, whichever comes first.
In the event of a dispute, we will attempt to find a JWST team member, instrument team member, or active professional astronomer to resolve the dispute via a public social media post. In the event that this does not resolve the dispute, that wager is off.
My real name is Nils Enevoldsen. You can find a $10,000 wager I have accepted with Robin Hanson at https://twitter.com/robinhanson/status/1390439816148525058.
Do you accept?
I really want the Webb to work and would like this bet to somehow hedge my happiness. I would be happy to pay $1000 if it somehow contributed to future missions like this one being successful. Is there somewhere that money would do some good? Likewise $100 is not going to move the needle off the peg of how disappointed I will be.
What do you think about the money going to:
In the winners name?
I am, to be honest, substantially more interested in money going to me than in money going to someone else. However in the interest of compromise I would offer a 50/50 split with the Planetary Society (which is an excellent choice of charity). In other words, if the mission fails entirely, I will pay you $50 and also donate the Planetary Society $50 in your name. If the mission succeeds entirely, you will pay me $500 and also donate the Planetary Society $500 in my name.
Are these terms acceptable? If they are, please also let me know your real identity so that we can both be held accountable.
Every finger and toe on my body will be crossed for a month straight between launch and deployment.
Anyway, I'm a bit of a JWST pessimist too, but I don't find any of your arguments very convincing. It feels like you're cherrypicking bad things about the program without doing a very good job quantifying why they're supposed to matter in the big picture of absolute risk.
The sunshield is a crazy idea and no one challenged it. Even worse, it is impossible to test it on earth. Just about every (partial) test of the shield has revealed problems that have been patched instead of starting over. If they had made the Webb telescope nuclear powered, many problems would go away - including deploying a 5 layer, experimental sun shield.
I think that people are also going to look at the transformation that NASA went under the last 4 years, with the rise of SpaceX, and think that this was the second most disruptive time. In both cases, the administration was run by a administrator, not a scientist.
Quote from the JWST’s user documentation: https://jwst-docs.stsci.edu/jwst-observatory-hardware/jwst-o...
So no significant acceleration event is expected as they enter an orbit around L2.
Furthermore they will have to keep doing orbit maintenance burns every 21 day while there, so they must have designed the structure with that in mind.
This paper discussed the Monte Carlo method they implemented to plan and control the orbital insertion.
At page 16 they discuss nominal burn times. The MCC-2 burn has an associated deltaV of 0.712m/s. (That is the first of many burns which happen in the unfolded state) Of course the real value will depend on how accurate the previous burns happens to be, but it provides a rough estimate of what we can expect.
They would not risk damage to the telescope if the processes involved weren't already rigorously tested and safe. There's a lot of eyes and quite a lot of money riding on this project.
> STScI announces the selected JWST General Observer programs for Cycle 1. This follows the review of submitted proposals by the JWST Telescope Allocation Committee, which made recommendations to the STScI Director, who approved the final selection. The selection is scientifically balanced, with a distribution of science categories that broadly matches the submitted proposals. More detailed information about the approved proposals is now available.
> The Cycle 1 GO program includes 266 proposals for approximately 6,000 hours of JWST prime time and up to 1,231 hours of parallel time, as well as 15 archival and 5 theory proposals. This milestone completes the definition of the first year of JWST science, as envisioned by a broad, worldwide community of observers. The selected proposals were prepared by more than 2,200 unique investigators from 41 countries, including 43 US states and territories, 19 ESA member states, and 4 Canadian provinces.
Interesting. I thought all the fuss was because it would be in the visible spectrum (i.e. nice magazine photos and desktop backgrounds)
Disclaimer: I know very little about astrophotography
Only F070W is partly human-visible, everything else is off into infrared, as you'd expect.
Also a good range to sniff the atmospheres of earth sized planets for chemical composition, if everything works just right.
In theory Webb might be able to sniff out a water/nitrogen/oxygen atmosphere, some thought to most likely come from plant life.
When will it be shipped to French Guiana?
Most of them can't be found unless you hover your cursor over the box, which is less than ideal to say the least.