What are the reasons? I'm sorry ~ I'm ignorant on the topic, but I'd love to learn more. Why/what are the reasons?
the post is really not very long and I would suggest getting it straight from the horse's mouth, but for those not willing to devote a click here are arguably the most relevant bits!
"deployment surveillance cameras would not add significant information of value for engineering teams commanding the spacecraft from the ground."
"Webb’s built-in sense of ‘touch’ (for example, switches and various mechanical, electrical, and temperature sensors) provides much more useful information than mere surveillance cameras can," said Geithner. "We instrumented Webb like we do many other one-of-a-kind spacecraft, to provide all the specific information necessary to inform engineers on Earth about the observatory’s health and status during all activities."
From the article so people can just debate NASA's own reporting:
> Although infrared or thermal-imaging cameras on the cold side could obviate the need for illumination, they would still present the same harnessing disadvantages. Furthermore, cameras on the cold side would have to work at very cold cryogenic temperatures.
As to using infra red camera, they simply don’t work on objects the same temperature as the camera. NASA could have sent one up with a cooling system to look at the cold side of the sunshade, but again weight and pointlessness means it’s just wasteful.
Whether the telescope is reflective enough to get a good photo is another matter - I would guess not, it's designed to minimise stray light.
As for IR, the telescope is probably bright compared to the background at least for now. The main issue though is whether you'd need to actively cool the engineering camera. Cooling stuff in space is difficult because you can only really dump heat via radiation. It's probably not worth the weight to carry a separate cryocooler just for that. The inability to conduct heat is partly why it takes so long to cool down, aside from minimising thermal stress on the infrastructure.
[1] The main reason they exist is so that you have a point of reference when walking about outside, particularly on foggy or cloud days. The meteo folks also use them as visibility markers in winter - e.g. IceCube is something like 1km from the station by line-of-sight. Turning them off for a brief period is usually fine and we'd notify the station before we did it. On a clear night though you don't need them at all.
If you travel to somewhere with essentially zero light pollution, like a desert, if it's a clear sky you can see with starlight
Question: how much (if any) of that light is due to atmospheric scattering? ie, the sun's light hitting the daytime side of the earth, being scattered in our atmosphere, and faintly illuminating the night side of our planet? Would the same be true in the zero-atmosphere environment of space?
Here are some possible answers: https://space.stackexchange.com/questions/25901/how-bright-i...
Possible that some of it is from scattering and then if course you wouldn't get that in space as there's no atmosphere to scatter from! Scattering is incredibly faint though, even compared to starlight.
See also gegenschein and the Zodiacal light - both are backscatter effects.
To be more specific; It's "parked" in an orbit [0] that constantly puts Earth between the sun and James Webb.
So it's not only aimed away from the sun, Earth is also acting as a planetary scale sunscreen for it.
https://jwst-docs.stsci.edu/jwst-observatory-characteristics...
Of course a solar powered satellite can’t be parked in the shade. Can’t believe I never thought about that.
Surely they considered that, and the wins would have been massive -- no sunshields needed. So I'm sure the downsides must have been massive as well. Not enough plutonium fuel, or perhaps it just wouldn't provide enough power over the life of the mission. And of course the radioactive fuel would generate its own heat as well.
Now I need to find out more about that decision....
edit: Another commenter mentioned, "The earth's shadow never reaches L2 anyhow - it's only penumbra at that distance since the angular size of the earth is smaller then the angular size of the Sun." If that's correct, then there was never truly an option of "parking it in the shade" anyway.
I guess it gives you a very stable position for observations, but why not just put it in solar orbit then? Then again this is kind of a solar orbit that happens to stay close to the Earth at all times so that's a plus for comms.
It also is handy to keep the closest IR sources (Earth and moon) in the same direction as the sun at all times so there is never a point where you have a significant IR source above the sun shield.
The JW orbit semi major axis (about the L2 point) is order of 500,000 km. The radius of Earth is about 6500 km. Thus, the shadow of the Earth is extremely small compared with the excursions of JW.
So in this sense webb is already a camera which can photograph itself!
This capability exists for mirror alignment: They'll point webb at an isolated star, switch to focusing on the primary mirror, swap in optics that cause small phase differences to result in diffraction patterns, and then they can use the resulting images to fine tune the positioning of the mirror segments to a small fraction of the wavelength of light that they're using.
I'm not sure if that's correct - there's a lot of photons hitting the telescope (the night sky), and night vision systems can work off of a relatively small number of photons
Your position is that they should have added significant complexity to a maneuver that was already the most complex of its kind. A maneuver with $10 billion and two decades of work on the line. In order to make the first 30 days of a 10+ year mission marginally more entertaining.
You propose this while fully aware that the "entertainment" in question consists of things unfolding in extremely slow motion, in total darkness.
I mean, okay.
(Thought experiment: when you think about the Hubble, do you think about the day they shoved it out of the shuttle's cargo bay, or do you think about those groundbreaking images it captured during its multidecade mission?)
The dark side of the JWST (where all the instruments are) will be operating very close to absolute zero and in near-absolute darkness which, of course, is the entire point of the mission.
A selfie camera there would need to function in that environment, while also somehow not polluting the instruments on that side of the camera with heat.
It's surely do-able, but it's a more complex engineering task (and would therefore require more tradeoffs) than operating a camera in the relatively balmy environment of Mars, where heat pollution is of no concern because of the different nature of the mission.
Keep in mind that doing this on the JWST also need to have been accomplished with decades-old technology, given the extremely long design and engineering lifecycle of a complex space mission.
It's only good if you ignore the cost, and look only at the benefits.
And yes. Hubble being deployed was a big deal.
Even Hubble didnt really have any of that that I am aware of. Most of the pictures of hubble itself are from servicing missions.
Sure you have some rover selfies on Mars, but thats not the sole purpose of the instruments, quite the contrary really.
According to the mission director SmarterEveryDay interviewed on his YouTube channel recently, the James Webb Space Telescope is so sensitive it could detect the heat signature of a bumblebee at the distance of the moon.
I’m pretty sure if you asked the astronomers if you could put a 5 Watt webcam on the dark side of their sun shield for the social media clicks, they’d tell you to fuck right off to L3…
So no, it can’t detect a blue whale… ;-)
The recent filming of EDL of the Perseverance rover was spectacular, but a significant aim of that mission and indeed most of the recent mars rovers has been to inspire an interest in exploration and science in the public, a significant part of that is getting happy snaps of events as they happen. The pictures taken were also of significant interest to the engineers involved as they showed events that were extremely dynamic, video being one of the best methods to gain information about the events without impacting the operation.
Web is more aimed at direct science, the products of which will, as happened with Hubble be used to make pretty pictures, which in themselves have limited scientific value, but are of enormous value in engaging the public. This combined with the difficulty and risk of capturing meaningful images given the environment makes live video a non starter.
Since you've indicated an unwillingness to read the blog post I'll summarize briefly:
A camera on the "light" side of JWST would need its own heat shielding and wouldn't show us any of the instruments.
A camera on the "dark" side of JWST would need to function at temperatures close to absolute zero. It would somehow need to do this without disturbing the ultrasensitive instruments on the JWST.
This would have been needed to be accomplished with, essentially, 10-30 year old technology as the designs for spacecraft like this need to be locked in far ahead of time due to the incredible complexity of deep space launches.
In both cases the cameras would need power and data cable routing, and given the various harsh constraints involved (complexity, budget, liftoff weight, size) would have involved compromises in some other area.
I’ve read the article and I’m not criticising NASA’s decision. I’m just pointing out that a cam wouldn’t need to bring significant complexity, not in the insane context of this project.
That 10 billion was funded by taxpayers, and the assertion that at the very least there should have been a possibility of those taxpayers seeing the fruits of their money through pictures instead of some intractable telemetry is a fair one.
taxpayers seeing the fruits of their money through pictures
It's a telescope, you see.
That's why I don't understand this debate. You'll be getting lots of spectacular images from the earliest moments of the universe. Is that clear? We are getting a time machine here. We're just not getting selfies.
What if the public funded it and tolerated
the cost overruns
You'd still face the hard payload constraints of the launch vehicle itself. Every kilogram and centimeter devoted to this camera system (and the associated power and shielding requirements) would represent kilograms and centimeters that would need to be chopped elsewhere. You'd need to compromise or eliminate other aspects of the spacecraft, and/or tolerate the increased complexity and risk resulting from the inclusion of a zero-science-value selfie camera.
I would expect HN readers, of all folks, to be really familiar with the concept of the harsh realities of engineering solutions for resource-constrained environments.
Anyway, the armchair spacecraft designers among us clamoring for a selfie camera might as well go full armchair spacecraft designer. Tell us which of the JWST's instruments you would have compromised or scrapped in order to accommodate the selfie camera.
When it's later found in the episode, it's found with the lunar ascent module still attached. Because the astronauts ascended in this module, only the descent modules should be there, so you might at first think that this is a blatant mistake on the part of the writing staff and you might hope someone was fired for that blunder[1]. However, if you pay close attention, there's a plaque behind Leela while she's in the ascent module that states "Lander returned to this site by the Historical Stickler's Society."[2]
[1]: https://www.youtube.com/watch?v=FTxw5nQX7SA [2]: https://www.reddit.com/r/futurama/comments/91kssj/i_didnt_wa...
This is the unfortunate reality of space: The images we see from the Hubble, et al, are exposed for minutes if not hours, and processed to bring out colors invisible to the human eye. An astronaut flying to see the Webb, or one of many other "well known" astronomical landmarks would see either nothing or a faint smudge without a telescope or other enhancements.
The aforementioned NASA blog post goes into the many other reasons this wasn't practical.
It makes it easier when you go back five years later and ask for more money if people can see the multi-million dollar toy they paid for.
Likewise, for Voyager/Cassini/Huygens/etc? Don't remember any selfies from those. We merely had to settle for the spectacular, never-before-seen images of other worlds. Guess they were failures. :-(
Secondly, do we collectively as smart people honestly care what the ivermectin crowd thinks about exploring the cosmos?
this is just a guess though.
- Hubble/COBE level. Refuel it!
- LHC level: Meh, let it rot.
Tbf it is less about the device (and the people working on it) and more about what kind of fundamental changes to our understanding of the universe is provided by its observations. BTW I am pretty bullish on that front.
That being said, and I haven't done the math, but I think a Falcon Heavy and Dragon could do it at least in terms of delta V; although there are numerous problems with that like the fact that the dragon doesn't have a proper airlock for starters.
It is crazy to think about.
I haven't done the math myself, so I'm certain one side of that equation is wrong, but that seems hard to believe!
[1]: https://mobile.twitter.com/gfish/status/1479339620785524736
In other words, Webb is only one TEN THOUSANDTH the apparent size of a galaxy that's a _billion light years away_
That's just mind numbing to consider!
1) how absolutely mindblowingly big space is
2) how bad humans really are at intuiting things at the scale of space
https://en.wikipedia.org/wiki/Ward_Cunningham#%22Cunningham'...
But I want to reiterate that what's meaningful about this discussion is in part how unintuitive things at the far edges of our scales of perception really are. It's a muscle that, left untrained, will lead you to make incorrect characterizations like the one I made.
JWST is three light seconds from earth
The L2 point is about 1.5 million km from earth [0]. The smallest size Hubble can resolve is about 1/20 arcsecond [1]. It's in a pretty low orbit, so is effectively "on earth" relative to the distance to the L2 point where JWST is. Calculating the size of an angular measure at a given distance [2], you get about 727m [3].
[0] https://en.wikipedia.org/wiki/Lagrange_point#L2_point
[1] https://illuminateduniverse.org/2019/04/11/angular-resolutio...
[2] https://astronomy.stackexchange.com/a/20728
[3] https://www.wolframalpha.com/input/?i=tan%28%281+arcsec%29%2...
Maybe when we have active bases on the moon or Mars would a rendezvous with L2 be feasible but not before. Hubble is in low earth orbit and far more accessible.
On the other hand, with how delicate the optics and sunshield are, a servicing mission might not be worth it. At that point NASA might find it more productive to build a larger telescope, except this time it could again be designed to be manually deployed and serviced, thus not needing the complex automated deployment that delayed the JWST so much.
And JWST is really far from earth, starlink would do nothing.
If you have a tethered camera which uses the tether as its power source which is out in front of the scope, wouldn't it be able to "stare" back at the Business Side of the mullet and stream the Party back to earth?
Or does a teathered bot risk messing with the orbit of the scope?
How much actual pull strength is requireed per kilo to re-orient something in space, meaning: How easily could say an astronaught pull on a cable and change the orientation of an object of much larger mass?
What if there were a gyro-ratchet:
Gyros that spin, and are tethered to a thing. There are multiple of them and they "yank" a small amount by spinning their gyro/flywheel a bit to initiate a pull... but there are many of these extending off tethers to orient something...
What if the tethers are like a flat ribbon cable of super thin solar collecting "flat noodles" - they provide power to the orienting gyros...
but how do you untangle things in space if stuff goeas awry...
---
Maybe the craft only deploys gyros, via tethers, when it needs alignment - re-pointing... and reels the gyro back in when done...
or reels them back out when the tether should use solar to trickle re-charge the gyro battery.
But why should imagine anything?
Specifically the terms HollyWood (where that comes from is Pagan Druids, as that is where they took their Wands from which CAST SPELLS... Tele-vision, broadCASTING, Programming -- etc, its all there...
Spelling - to create/cast - cast as into formation....
Imagining --- is an interesting word...
its a case of your can't see it because there is no light, not because you dont have an angle of it (although that is also a chalange to overcome.
I understand the reasons for not putting a camera on or near the JWST, but I’m still a little sad that we’ll probably never get to see the thing in situ in all its operational glory.
Maybe one day when it finally expires, we can launch a “sample return” mission to tow it back.