even if not actually staying in space, just seeing that thing launch will be Eeeeepic
#James Webb Space Telescope 🔭
cerulean thorn
topaz gorge
Yee boiiiii
old charm
Everyone's interested about the telescope, and I'm more interested in the rocket and the actual process of what happens when it gets there
Not the first telescope/probe at the L_2 point it seems, Planck and Herschel were there before it
modest dune
I've certainly wondered about the relative risk of space debris in the area
I guess L2 is in the unstable category so it's probably not so bad
old charm
Gaia is there at the moment as well apparently
Planck was moved to a "graveyard orbit" out of the way apparently, Herschel is still out and about
cerulean thorn
the L points area gigantic, the chance of several vehicles colliding there is almost non-existant
the entire semi-stable area is several times bigger than the earth itself
and we have a gazillion sats just on thin lines around the planet, not colliding (unless intentionally shot...)
modest dune
makes sense
modest dune
@quaint plaza
brave coral
oop
modest dune
hehehe
quaint plaza
buh
I missed the launch because I watched a movie with a couple friends ;-;
also no servers have JWT emotes
modest dune
I ended up waking an hour late to catch it, but needed the sleep, been recovering from a cold for days
brave coral
COVID?!?
modest dune
is there a site tracking the individual critical points of failure?
wispy sun
There's at least one NASA project manager in the server :)
brave coral
who??
modest dune
oh I'm a derp, didn't see that part on the pinned message site
modest dune
j5 with the insightful inciteful questions :P
brave coral
it is YAY
noble quarry
since the launch went so well, I consumed the JWST gingerbread
wispy sun
Did anyone hear that the solar panels deployed slightly early?
brave coral
!!!
modest dune
After separation but not as much later as intended?
noble quarry
Did anyone hear that the solar panels deployed slightly early?
it was so excited to finally be in space
wispy sun
Kinda cramped in the spaceship!
carmine olive
Did anyone hear that the solar panels deployed slightly early?
it looked beautiful
red sail
Jesus Would Space That
That's what popped into my mind when I saw that cookie
noble quarry
Just Went Space Today
red sail
Ooo that one is good
modest dune
That's dedication
brave coral
nice!
plucky merlin
That's dedication
I'm going to do that too sometime in the next few months 🙂
I think it'll be possible for me to snap an image like that of the JWST once it reaches its L2 orbit at 1,000,000 miles from Earth
ornate marsh
there's something a little weird about something orbiting empty space
usually with orbits it's a barycenter located inside one of the bodies, but with a halo orbit it's just empty space
plucky merlin
It's really orbiting the sun and the earth, and being pulled on by both of them at once. And the strength of the Earth's pull relative to the Sun's pull changes as the telescope moves slightly closer or farther from the Earth
calm flint
I think the idea of L2 is to orbit the sun, while using the Earth as a shield from the sun.
So the orbit isn't around Earth at all, but synchronised to follow Earth's orbit around the sun.
As opposed to L1, which means also being in sync with Earth, but always in front of the sun.
ornate marsh
things in orbit around L2 try to avoid the shadow so they can get more solar power
safe bronze
Staying in the shadow would probably be good for JWST, but it does not have an RTG, so it's in a vertical orbit around the shadow
calm flint
But you don't want solar power, because that bring heat which you're actively trying to avoid in order to maintain 6K operational temperature for your instruments.
ornate marsh
but you also need solar power to run your instruments
safe bronze
calm flint
Yes, but how much?
If you can get by on solar reflected off other bodies, you might get the power you need.
safe bronze
That would be extremely little energy
calm flint
If not using the Earth as a shield was desireable, I think L3-4 would have been better, as those wouldn't require constant adjustments to maintain, from the few infographs I've read.
Or perhaps the telescope exposes itself to recharge, then repositions in the shadow to operate?
safe bronze
It stays far away from the shadow, instead creating its own with the solar shields
ornate marsh
If not using the Earth as a shield was desireable, I think L3-4 would have been ...
maybe the extra 0.01 AU will be the difference ¯_(ツ)_/¯
calm flint
Ah, so it orbits L2, it's not in a static position.
plucky merlin
I think the idea of L2 is to orbit the sun, while using the Earth as a shield fr...
L2 DEFINITELY requires both the Sun and the Earth's gravity to work
No Earth? No L2 point exists
ornate marsh
well, duh
ornate marsh
Lagrange points are solutions to the three-body problem
which by definition requires 3 bodies
plucky merlin
Yeah, I was replying to what Jastebro said further above
safe bronze
If not using the Earth as a shield was desireable, I think L3-4 would have been ...
I'll guess this is mainly to keep the earth and any lines of communication out of view from the telescope
safe bronze
Yeah, I was replying to what Jastebro said further above
Before reading all the responses to it after...
ornate marsh
maybe it's so it can shield from the Sun and Earth at the same time?
plucky merlin
I believe the reason they chose L2 was so they would be shielded from the unnecessary thermal output of the Earth at all times by the JWST's sunshield
calm flint
Yeah, I was replying to what Jastebro said further above
Yes, but what would the specific benefit be of L2 over the other L's?
Maybe that it just is the furthest from the sun?
plucky merlin
"This allows the satellite's large sunshield to protect the telescope from the light and heat of the sun and Earth (and moon)," they added. "This is why the telescope will be out at the second Lagrange point."```keep them within a couple degrees instead of 60 degrees like at L4/5
calm flint
That would explain it. IR noise from the Earth.
Guess that's a problem you'd not consider outside trying to stay near absolute zero with minimal effort.
ornate marsh
gotta keep those darks dark
plucky merlin
gotta keep those darks dark
Imagine if your mirror glowed in the wavelengths you're trying to observe 🙂
safe bronze
Right, L3 and L4 are also significantly further away - light-minutes instead of seconds
ornate marsh
imagine if your camera randomly generated a signal just because it was warm
calm flint
Distance itself wouldn't be a problem if you're just patient.
Perhaps an issue of signal strength for the satellite to communicate, though.
safe bronze
You'd already need a stronger antenna (more heat generation), or accept much slower data transfer
plucky merlin
imagine if your camera randomly generated a signal just because it was warm
That's a concern in visible observations too, but it's not the primary reason why the IR cameras need to be cooled down so much. If the telescope components aren't cooled down that much, they will literally glow in infrared like every material does at "normal" temperatures. It's the IR equivalent of a material being red-hot and giving off glowing light.
The mirror, the scope assembly/truss, the camera body, sensors, pretty much everything
plucky merlin
@ornate marsh You got a scope?
ornate marsh
just the ones at my uni that we use
plucky merlin
Ah, very cool
Plug in some JWST ephemerides and snap us a pic of it, please 🙂 https://ssd.jpl.nasa.gov/horizons/app.html#/
ornate marsh
ah, well, that should unfortunately be past tense since I graduated
plucky merlin
Dang. 🙂
My scope's packed away right now and I don't feel like getting it out til I move in a few months
calm flint
So, hypothetically, how powerful a laser would you need to interfere with a 10B$ satellite?
ornate marsh
depends on what kind of interference you want to achieve, I guess
but pretty powerful
plucky merlin
So, hypothetically, how powerful a laser would you need to interfere with a 10B$...
A megawatt ground-based laser can blind a spy satellite 300 miles above. That's the only data point I got for you
calm flint
Anything that would affect it in a meaningful way, such as adding heat over intended specs.
Spy satellites are looking down, though.
ornate marsh
the shield blocks the camera and is designed to shed the 500 kW it receives from the sun
safe bronze
ornate marsh
plus at 1.5 million km you have to deal with potential loss due to the inverse square law
calm flint
https://what-if.xkcd.com/13
The earth woud deorbit over the ammount of cats jumping for the moon.
safe bronze
lol
ornate marsh
hmm, using the 5 min from that post, at the distance of the JWST that would cover an area 12 billion times the size of the shield, so that's another factor to worry about
plucky merlin
A much more realistic concern would be JWST control center being hacked and malicious commands sent to the JWST
carmine olive
I doubt it's on the internet
zero
zero fucking chance it is network connected whatsoever to the global Internet
plucky merlin
Iran's nuclear centrifuge network wasn't on the internet either
It didn't stop a state-sponsored cyber attack that wrecked their centrifuges in arcane ways
autumn sierra
Speaking of noise - there's been normal Earth cameras that have a feature against that
I think it was a Kodak I heard. To take long shots (particularly night), the shutter/iris would be closed for the "second half" of the shot, and it would subtract the "null" noise from the original shot.
glad mist
I know they planned the velocity and such for the next 30 days. Still, it is surprising how fast it was going yesterday compared to today. I wish there were an Excdl sheet someplace with expected distance traveled per day for the entire trip
ornate marsh
I think it was a Kodak I heard. To take long shots (particularly night), the shu...
that's how you usually deal with dark current
safe bronze
I know they planned the velocity and such for the next 30 days. Still, it is sur...
It's basically still decelerating at 0.9 or 0.8g...
glad mist
Is it actively decelerating using the thruster?
ornate marsh
could be gravity
safe bronze
Gravity, it doesn't have thrusters to decelerate with
plucky merlin
Speaking of noise - there's been normal Earth cameras that have a feature agains...
Astrophotographers already subtract a variety of noise patterns from their images using flats, darks, and bias frames
glad mist
If it was going 7 meters per second at the fastest and has slowed down to 1 meter per second now…
plucky merlin
A separate processing step for those will give greater control over it than just trusting the camera to do it itself
autumn sierra
Without extra information you can't account for random noise per-se without making worse assumptions. Any extra reliable source of noise improves that
plucky merlin
The camera feature you mentioned is just dark subtraction
Astrophotographers definitely already work that into their process 🙂
Most commonly by just covering up the camera or telescope and taking an equal length exposure of no light hitting the sensor
carmine olive
the james webb does not move at speeds in meters per second
plucky merlin
well-immunized*
ornate marsh
To measure imperfections in the lenses and mirrors
plucky merlin
It is the era of COVID-19, after all
brave coral
But you don't want solar power, because that bring heat which you're actively tr...
james webb is specifically on an orbit where it will never be in the shadow of earth in order to get maximum solar power at all times
brave coral
Lagrange points are solutions to the three-body problem
2 body problem*
brave coral
My scope's packed away right now and I don't feel like getting it out til I move...
what kind of scope is it?
wispy sun
something I find impressive is that it manages to get 2kw of solar power
and that's a pretty low amount, all things considered
brave coral
thats basically less than a cell phoen
wispy sun
what cell phone uses 2kw of power???
quaint plaza
Apparently the actual telescope uses a very low amount of energy compared to its satellite stuff to maintain itself
glad mist
I assume the motors used to move the mirrors use a bit of power
brave coral
not surprised, my telescope takes up no energy!
quaint plaza
I wanna telescope ;-;
glad mist
I know where there is a big one. It is just a bit of travel though.
wispy sun
humans being composed of telescoping rods 🤔
brave coral
18% of the way there!
ornate marsh
2 body problem*
Three bodies: the Sun, the Earth, and the spacecraft
brave coral
you're right! i looked up the history. I assumed the L points were discovered by analyzing the gravity field of two bodies, but Lagrange actually found the orbits of 3 bodies
though here's something I did not know: Euler discovered L1, L2, L3 before Lagrange tooked at it!
safe bronze
Gravity, it doesn't have thrusters to decelerate with
Fun fact: there was a tiny chance that the solid rocket booster on the Ariane would overperform, causing the telescope to overshoot its destination without a way to slow down.
plucky merlin
what kind of scope is it?
8" Newtonian reflector
@brave coral Here's three geostationary satellites through my scope (22,000 miles away, actually a bit further in this pic)
glad mist
Thx!
plucky merlin
And here's the same three satellites but with my scope tracking the "moving" stars instead of the "stationary" satellites
glad mist
Very awesome
plucky merlin
I figure I have a decent chance of easily snapping the MUCH larger but 50x farther away JWST 🙂
glad mist
Seems like earth telescopes have a ton of satellites to see these days. (Whether you want to or not)
plucky merlin
Yeah, it's more of an issue around dawn and dusk though
And it's easy for amateurs to automatically subtract from their images while processing their stacks
glad mist
That’s great to hear
plucky merlin
Twitter
glad mist
Thx!
safe bronze
I figure I have a decent chance of easily snapping the MUCH larger but 50x farth...
I've already been seeing quite a few amateur pics and videos on reddit, so it's definitely possible :)
glad mist
Link if you see a cool one?
Though to be fair, you could link a pic of a satellite in LEO, and I likely wouldn’t know the diff
safe bronze
https://www.reddit.com/r/space/comments/ros0m5/photos_my_dad_took_of_the_james_webb_space/
Top of r/space right now, seems to be taken shortly after launch
There's a few more there pretty high up
glad mist
Thx!
plucky merlin
Though to be fair, you could link a pic of a satellite in LEO, and I likely woul...
Here's a satellite in LEO I snapped 🙂
glad mist
Thx!!
plucky merlin
That's the ISS
plucky merlin
Here's the ISS and the first Crew Dragon module about an hour after it undocked to return to Earth with Bob and Doug inside
brave coral
what mount do you have?
plucky merlin
And here's a few days before that, when the first Crew Dragon was still docked to ISS
glad mist
Might be ISS. Could be aliens. I can’t tell for sure
plucky merlin
I think I took these pics while I had my old Skyview Pro equatorial tracking mount (non Goto)
But then around that time last year I bought an EQ-6R Pro 🙂
plucky merlin
The ISS pics above are all me with the clutches off, just holding the telescope tube in my hands and pointing it at the ISS as it moves across the sky, so mount doesn't really matter for those
Yeah, EQ-6R Pro is as good as the memes say 
I'm super happy with it
plucky merlin
It's also my first Goto mount
Which removes a LOT of time spent star-hopping to find targets and stuff
It makes astrophotography vastly less annoying of an endeavor 🙂
pseudo comet
Glad to see others geeking out about this; I wasn't able to discord until now, but hoorah!
not that anyone cares but I spent hours in KSP trying to figure out how this profile makes sense. Best guess is a painfully low-thrust upper stage engine and I wan't going to double the time sunk into testing that hypothesis to point of failure/veracity
brave coral
I'm care, it's interesting and I don't get that trajectory eother
carmine olive
From what I can tell, altitude doesn't matter whatsoever anyway, only being high enough that air resistant is neglible so you can gain that sideways velocity
old charm
That would be my intuition. Go a little higher, then fall “sideways” to convert that potential energy into horizontal velocity in the direction they want… idk lol
stray kindle
Could it be something like a safety measure in case the second stage takes a while to ignite (as in let it freefall to have time to re-build vertical speed)?
safe bronze
I have definitely done these kinds of ascent profiles in KSP when flying with low TWR upper stages, lol.
Another option would be the SRB boosters combined with low manoeuvrability during atmospheric flight?
brave coral
it would make more sense to me if I saw it in 3D and also with labeled burns
brave coral
honestly I'm noire confused -- it makes it look like they pointed the rockets upwards!
at 12
carmine olive
Could it be something like a safety measure in case the second stage takes a whi...
not really, there's not a case where engine ignition doesn't happen on time but will happen with repeated trys
plucky merlin
This question was asked at the post-launch press conference, I was only half-listening to the answer, but it sounded basically like an Oberth Effect reason
cerulean thorn
gravity slingshot
brave coral
that's when burns are more effective the faster youre going, right?
cerulean thorn
rocket engineering is getting every little tiny bit of efficiency possible out of something by any tricks possible
safe bronze
that's when burns are more effective the faster youre going, right?
Yes
Faster or deeper in a gravity well... Not much difference anyway
cerulean thorn
because burning things for thrust really sucks
I'm surprised we're even capable of yeeting things into space with just dino juice
cerulean thorn
don't remember which scientist said at some point that if Earth was just 10% bigger we would have not left the atmosphere at all, the margin is so thin that we're -barely- managing to get out
brave coral
Faster or deeper in a gravity well... Not much difference anyway
well, if that were the case we'd all be going extremely fast!
safe bronze
We would be if not for the constant lithobraking :P
safe bronze
"Once you're in orbit, you're halfway to anywhere" -- Robert Heinlein
calm flint
I hear there's a handy dwarf planet available in our solar system. Perfect for our needs!
brave coral
We would be if not for the constant lithobraking :P
not just air, otherwise things on mecurcy would be going really fast because there's no atmosphere
cerulean thorn
anyway, until fusion drive or similar is invented
modest dune
This question was asked at the post-launch press conference, I was only half-lis...
the extra height from the first stage is wasteful since a gravity turn is most efficient if you constantly accelerate in a smooth arc, but the second stage booster didn't have enough thrust (due to a focus on efficiency) to maintain altitude purely through that horizontal action
so it's really due to limitations of staging being in discrete shifts rather than a continuous shift of variables
safe bronze
not just air, otherwise things on mecurcy would be going really fast because the...
Litho, not aero
brave coral
hehe sure
safe bronze
I hear there's a handy dwarf planet available in our solar system. Perfect for o...
I mean, our moon is basically a dwarf planet... Bigger than average even
brave coral
but it's not true that closer = faster in general, unless you happen to never be doing burns
calm flint
I mean, our moon is basically a dwarf planet... Bigger than average even
And no pesky atmosphere ruinig things with resistance either.
safe bronze
So yes, the Oberth effect depends on speed, and the common way to get that is to fall into a gravity well
Or in this case, not wasting energy climbing out of it too soon
brave coral
so did they actually point their engines up and burn to desend?
safe bronze
Doubt it, probably just went horizontal
brave coral
I would also be surprised if they did
safe bronze
As Iron said, the main reason is low upper stage thrust
brave coral
so were they sub orbital when they were descending?
safe bronze
Would have to see the velocity at that point
carmine olive
they would need to be so, I'd assume?
safe bronze
Probably still were. Orbital velocity is around 7.7 km/s
safe bronze
You're suborbital during most of the launch, even when going up, until you hit orbital velocity
brave coral
you're least not going down before that
safe bronze
Going up simply means you have a little more time to panic if something goes wrong before re-entering
plucky merlin
And a little more time for the Launch Termination Director to crack his fingers and laugh with evil glee
young locust
Glad to see others geeking out about this; I wasn't able to discord until now, b...
If you play rss/ro, launch trajectories like this are quite common
This is the explanation given in the guide for the pvg system used in Ksp ro
modest dune
one of those questions, aye
young locust
The previous point is relevant too
young locust
one of those questions, aye
The ksp realism community has a lot of those type of questions, I think due to the fact that actual rocket science is a little more difficult than stock ksp
Also due to the complicated process of getting all the necessary realism mods to work
pseudo comet
the extra height from the first stage is wasteful since a gravity turn is most e...
this exactly what the conclusion I alluded to. thank you, those who brought up the Oberth Effect (lower/faster more effective and fuel-efficient for moving apoapsis) -- that's why the dip is allowed instead of the first stage being even more vertical to compensate. Stock KSP doesn't really set this up, and threading the needle with a ridiculously artificially-nerfed Poodle was not something I was about to pursue (I did enough with the first stage and boosters to rule out a lot of alternatives)
noble quarry
you're least not going down before that
misjudging how much extra altitude is needed for the low TWR upper stage is always fun; definitely stranded at least one Kerbal in LKO after burning the whole upper stage just to barely stay out of the atmosphere ...
plucky merlin
The ksp realism community has a lot of those type of questions, I think due to t...
It's more of the fact that in real life (and in the realism mods) the margin of error for getting into space is vastly more narrow than with stock KSP
Stock Kerbin is much smaller than Earth, with much less gravity. When you put in a realistic Earth-size object instead, you have to absolutely min/max the rocket you're putting into orbit if you want to actually make it to space successfully
carmine olive
thank god ksp is smallee
quaint plaza
“Ksp realism community” ☠️
thorn musk
thank god ksp is smallee
there is a 3.4x scale mod which IIRC is the best one for getting "reasonable" rockets to kinda match IRL visually
or you can go for 10x for full realism and suffer
brave coral
28% of the way there!
reef sequoia
Wow, it's going way faster than I thought it would.
pseudo comet
velocity lower in the gravity well is much greater than higher, when in the same orbit
modest dune
plus it's slowing down the whole way there, so the first part is faster
proobably just a restating of that
pseudo comet
(because it is moving from lower to higher in earth's gravity well [moving away from earth] in a roughly-invariant orbit)
modest dune
aye
pseudo comet
something potential something kinetic energy something something
modest dune
I'm sure same-orbit would've been clearer to someone familiar with discussing transfer orbits in particular
pseudo comet
relevant:
https://xkcd.com/2501/
cerulean thorn
would be funny if they miscalculated something and it will just keep going...
wheeeeeeee... goodbyeeeee
pseudo comet
would be funny if they miscalculated something and it will just keep going...
hee hee, "Blame Jupiter"
safe bronze
would be funny if they miscalculated something and it will just keep going...
There was actually a tiny chance of the Ariane solid rocket boosters performing exceptionally well and causing the telescope to overshoot. It relies purely on gravity to slow down, and does not have any braking thrusters on the front. And I doubt pointing the telescope at the sun is an option...
red sail
Seems almost insane that they are just expecting everything to go perfectly in regards to that.
cerulean thorn
After 10 years of delays and millions of simulations and tests... it'd bettet go perfectly
brave coral
hey, that's cool!
wispy sun
plucky merlin
noble quarry
https://twitter.com/ESA_Webb/status/1475917532087341057
anyone have any nails left at this point? 😛
plucky merlin
Don't worry. All deployment steps for the James Webb Space Telescope will go flawlessly, and the telescope will go on to have a long, fruitful, and flawless future of space observation
I have foreseen it
brave coral
JWST will last for 30 years, you heard it here first
pseudo comet
I have foreseen it
Your overconfidence is your weakness
brave coral
we live in the best timeline for space exploration, god has ordained it
plucky merlin
> Your overconfidence is your weakness
Your faith in your friends is yours. 
carmine olive
wonder if the sunshield deployment has any "partial failure" cases
pseudo comet
I highly doubt they'd commit to such a complex and 'unpredictable' mechanism without a few survivable failure modes… but I haven't heard of (or gone researching) what those might be
carmine olive
however, partial failure modes do add complexity
young locust
I think I’ve heard that it can survive without every layer of the shield being fully intact
carmine olive
though it will not be as good at all
modest dune
I highly doubt they'd commit to such a complex and 'unpredictable' mechanism wit...
they did add tear-arrest reinforcement lines to the shield layers but who knows how likely those are to keep it meaningfully functional in the event that they become relevant
safe bronze
It was apparently worth adding them in
reef sequoia
Those aren't so much for the unfolding process as they are for micrometeorite impacts.
They didn't add them, and the sunshield got hit by a piece of space junk, the entire thing would shred to pieces.
cerulean thorn
I think it has a slight tolerance for a dust-sized micro-meteor punching a hole straight through (but only through the foil
however if it hits something sensitive in the detectors, yea, it's gg
brave coral
was the hubble subject to the same risks? (minus the irreparability)
cerulean thorn
hubble has a strong shell, it's much more resilient
modest dune
fewer angles of incidence for something closer to earth to get hit too
cerulean thorn
and that
but I'm quite sure the scientists have calculated the potential risks, and JW can probably take a few small hits
brave coral
fewer angles of incidence for something closer to earth to get hit too
id expect that there's a lot more stuff closer to earth. satellite debris, etc.
though of course im not sure
i also suppose that only things that are fast moving in relation to the JWT / Hubble are risks
if most things are happily orbiting L2, then a collision with one of them will be very slow moving
plucky merlin
was the hubble subject to the same risks? (minus the irreparability)
Yes, I wouldn't be surprised if there are known debris impacts on the Hubble's body
Yup Hubble itself has felt the impact of this debris, accumulating tiny impact craters across its solar panels that evidence a long and eventful life in space. ... Nine years later, the solar panels were again replaced and returned to Earth this time having accumulated almost a decade of impact craters.
Actual Hubble solar cells brought back to Earth in 2002
Such impacts occur quite frequently for all satellites, the main effect being a continuous but gradual degradation in the amount of power the solar arrays can produce.```From this article, wow it's got a LOT of detailed and extremely good info in it, highly recommend you give it a read. I'm surprised https://www.esa.int/Safety_Security/Hubble_s_impactful_life_alongside_space_debris
At the Hubble's altitude, there's approximately one micrometeorite of that size class in every 1km x 1km x 1km cube of space
brave coral
thank you for the photos, links and information. very interesting!
plucky merlin
I would assume that L2 would be much more clear of such natural particles than at roughly 500 miles altitude around the Earth
But I don't know for certain
safe bronze
Hmmm... Relative velocities out at L2 might be lower too, as you aren't at the bottom of earth's gravity well
plucky merlin
That's a pretty insightful guess too
brave coral
The impact craters were studied to determine their size and depth, but also to seek out potential new residues. Given that the chemical composition of the solar cell was known, ‘alien’ materials or elements could have been brought into the crater by the impactor.
Metals like iron and nickel would suggest an impact from a natural source – fragments of asteroids and comets known as micrometeoroids. The craters found in Hubble’s solar arrays however contained small amounts of aluminium and oxygen, a strong indication of human activity in the form of ‘solid rocket motor’ firing residues.
seems that a good amount of the impacts were from other space ships
safe bronze
Still way higher than what you need to punch though the solar shields though :P
brave coral
amazing how much they studied these impacts:
The space debris team, as part of a larger effort with partners in industry and academia, were able to match the shape and size of these craters to models of rocket firings that were known to have happened at the time, finding a match between craters observed and craters expected.
plucky merlin
I think that doesn't mean matching which rocket launch caused which debris, but rather just confirming that expected guesstimates of how much, and what size, of debris comes off of rocket launches was close to correct
i.e. something like "rocket manufacturers say they expect this many stray debris pieces of this size to come off, and according to that we'd expect to find that over x years, we would have a y% excess of man-made particle impacts" and then that's what they actually found on the solar panels
We know Webb will get struck by micrometeoroids during its lifetime, and we have taken that into account in its design and construction. We sized Webb’s main mirror so that even after years of little impacts it will still have the reflective surface area and quality necessary to do the science. We even did tests on the ground that emulated micrometeoroid impacts to demonstrate what will happen to the mirrors in space.
Similarly, part of the reason the sunshield has five layers is so it can tolerate more than the number of expected small holes, and even some tears, and still work as it should.
Also, almost all of Webb’s sensitive components (besides the mirrors and sunshield) are protected behind “micrometeoroid armor.” When micrometeoroids do strike, most are so small that they totally disintegrate upon impact, even when they hit something thin like thermal blankets or a sunshield membrane. Critical wires and electronics are shielded behind even more robust metal “armor” or inside metal boxes.```^ For the Webb, L2, and micrometeorites
pseudo comet
source?
plucky merlin
As far as damage to the mirror is concerned, any amateur astrophotographer can tell you that dust/blots/imperfections on the sensor or mirror have almost no impact on image quality, and in most cases can be 100% subtracted out
brave coral
thanks! its interesting to see how they were thinking about it. also interesting to know that its less dangerous at l2 than around earth
The engineering challenge is to operate Webb at extremely cold temperatures, since Webb is built at room temperature. Materials typically shrink at various temperature rates as they get cold. We have to build the Webb telescope in a way so that it shrinks to precisely the right shape and dimensions when it's extremely cold.
holy crap!
wispy sun
And that's all predicated on the solar shield working
plucky merlin
Don't worry. It'll be perfect. 
brave coral
its true. i looked into the future and saw the first image. its of the eagle head nebula and it looks great
brave coral
here's an interesting thing I found about using nuclear power vs solar power on the JWT
Wikipedia says that JWST has about 2,000 watts of solar power.
Wikipedia says that NASA's flagship RTG, the Multi-mission radioisotope thermoelectric generator has an output in the beginning of about 2,000 watts of thermal power and only 125 watts electrical, after say 10 years that might be only 105 watts.
So you would need about twenty 45 kg RTGs, or another 900 kilograms to equal the power output of the much, much lighter solar panel, a far, far simpler technology you can almost order out of a (very fancy space) catalog these days.
noble quarry
here's an interesting thing I found about using nuclear power vs solar power on ...
what we need is NASA's Kilopower program (kW-class nuclear reactors)
wispy sun
What's the efficiency like?
thorn musk
yeah for stuff around earths distance RTGs dont make sense
theyre more for distant solar system objects, deep space, or extended nights
safe bronze
here's an interesting thing I found about using nuclear power vs solar power on ...
I do believe it only needs 1kW during normal operation, but that's still a lot of RTGs
safe bronze
Tbh so does catching sunlight :P
thorn musk
sure but I doubt its as much
wispy sun
You could (slowly) cook an egg on the hot side :)
brave coral
sunlight hits you regardless right?
thorn musk
solar power = larger area
plucky merlin
noble quarry
solar power = larger area
but in general that area isn't useful as a radiator (at least compared to a dedicated radiator)
brave coral
all according to keikaku
pseudo comet
plus RTGs generate heat :P
that's the T part in RTG
thorn musk
as in the larger area typically oriented to capture sunlight will add more heating
noble quarry
sure but I doubt its as much
but it is true that a conventional RTG will be less efficient than a solar panel nowadays
thorn musk
that's the _T_ part in _RTG_
the T is Thermoelectric if you want to go there :P
the R generates the heat
pseudo comet
(yes, the heat is actually the radioisotope decaying…)
safe bronze
lol
thorn musk
TG just makes use of it
noble quarry
NASA is also looking into coupling Stirling engines to radioisotopes (for higher efficiency)
pseudo comet
HA! someone picked up my abanonware!
https://spacedock.info/mod/1773/JDiminishingRTG
thorn musk
risky, constantly moving parts = prone to failure
noble quarry
risky, constantly moving parts = prone to failure
true, though good seals and magnetic bearings, maybe now feasible
it's something we're going to have to get good at eventually anyway
thorn musk
I mean, theres little reason not to do it, but I think itd fail quickly
safe bronze
HA! someone picked up my abanonware!
<https://spacedock.info/mod/1773/JDiminishi...
And then abandoned it again :P
wispy sun
Who's going to pick it up this time?
noble quarry
I mean, theres little reason *not* to do it, but I think itd fail quickly
well, apparently a couple of stirling engines have been run continuously for 7500 hours (on Earth, I think): https://ntrs.nasa.gov/citations/20050186830
brave coral
And then abandoned it again :P
https://gitlab.com/N70/JDiminishingRTG
it 404's or is private :(
wispy sun
https://github.com/justchen1369/acolyte-fight I have the only public copy of this game's source code lol
safe bronze
1 Fork
brave coral
crazy how much power webb needs. curiosity only uses 1 reactor and 110W electrical power. just what is JWT doing??
noble quarry
crazy how much power webb needs. curiosity only uses 1 reactor and 110W electric...
powering the cryocoolers, image sensors, and antennas, I'd expect
plucky merlin
Curiosity doesn't do much for most of the day, just charges its batteries
last shadow
wait, how much does webvb need?
plucky merlin
And I think it only needs to do heavy communications with the Odyssey probe a few hundred miles overhead, which relays everything back to Earth
noble quarry
having trouble finding a breakdown of JWST's power budget
brave coral
i found this
While Webb will only use 1 kilowatt of power, the solar array is capable of generating nearly double that amount to factor in the gradual wear and tear of a harsh space environment.
so that's 1000 watts down
plucky merlin
having trouble finding a breakdown of JWST's power budget
I wish they released a lot of this kind of detailed info
noble quarry
it's got to be in a design document somewhere, but apparently it's somewhat hard to find as there's no link to it yet on wikipedia
plucky merlin
I don't think it exists publicly
We also don't even know if JWST has a docking ring for sure in its current design
In 2007 they said they were adding one, but since then we've heard nothing about it despite it being a hot issue
brave coral
so the cryocooler can cool 1/4 watt
plucky merlin
If there were any sort of detailed technical documents or info out there, it'd be a settled matter
brave coral
but it takes up to 325W of power to do that cooling
so we have 675 unexplained watts
plucky merlin
Commo is probably going to be somewhere between 5 and 50 watts, just ballparking it
600 watts is what a decent desktop computer draws at full load
last shadow
so we have 675 unexplained watts
contacting aliens 🥷
noble quarry
looks like the instrument package will draw no more than 740 W, based on a 2007 document (page 27): https://spacese.spacegrant.org/uploads/Requirements Config/JWST Mission Requirements Document.pdf
plucky merlin
Hard to imagine exactly what the JWST would be doing with that much juice on average
noble quarry
I can't imagine that requirement has changed much, so we can probably assume ~700 W for instrumentation
which will be all the cameras, basically
brave coral
wtf this just blew our power budget
plucky merlin
Build another boiler and power plant
last shadow
07 is 14 years ago so probably has changed
better technology, removign excess parts
or maybe plain up installing 
brave coral
probably removed the SUSHI
noble quarry
wtf this just blew our power budget
well, or they improved the cryocooler efficiency, and/or reduced instrumentation power consumption
also, isn't the power budget 2 kW anyway?
brave coral
While Webb will only use 1 kilowatt of power, the solar array is capable of generating nearly double that amount to factor in the gradual wear and tear of a harsh space environment.
noble quarry
ah, interesting
last shadow
wtf this just blew our power budget
on the other hand they messed up and only we know
noble quarry
that seems highly unlikely, lol
noble quarry
ok, so we know that the warm instruments in the ISIM generate 230 W heat (page 7): https://jwst.gsfc.nasa.gov/resources/ISIMmanuscript.pdf
I wonder if the power consumed by the cryocoolers is included in the overall ISIM power budget; if so, then that might explain things
noble quarry
https://cryocooler.org/resources/Documents/C19/343.pdf
if we use the 360 W value from here, and add the 230 W, then that gives 590 W
well, in any case, I'm certain that the engineers and scientists did the calculations correctly
brave coral
hehe yes
noble quarry
it's only in KSP that you launch without enough solar panels or batteries 😛
pseudo comet
that's what the alternators on the engines are for 
last shadow
well, in any case, I'm certain that the engineers and scientists did the calcula...
🤷 i really hope so
plucky merlin
thorn musk
I dont know how cold that is
reef sequoia
Lol, implying that English speakers don't use metric
plucky merlin
They're only updating the temperatures once a day, it looks like
For all I know, someone is literally typing them into the web page once a day
old charm
aft momentum flap
Is that what they’re calling it these days?
wispy sun
Shiny
noble quarry
I think it's funny how none of the videos have sound
in space, no one can hear your flaps
modest dune
solar shield covers released
brave coral
tiny tear invisibly forms
safe bronze
Even if it were a massive one, I don't think we'll be seeing it from here
wispy sun
was each latch a SPOF?
brave coral
people have talked about 316 single point of failures or whatever, but ive never seen them all listed
noble quarry
people have talked about 316 single point of failures or whatever, but ive never...
it's bad luck to have them all in one place 😛
brave coral
hehe
safe bronze
Yes, we need to keep at least one safe somewhere else, as a designated survivor
red sail
it's bad luck to have them all in one place 😛
Like on the same spacecraft?
plucky merlin
Full resolution original video of the JWST separating from the Ariane 5 upper stage. Notice a few seconds after separation, you can see reflections on the JWST of the Ariane 5's cold gas thrusters firing. Due to the JWST being off center mass, when it separates it induces a slight spin on the Ariane 5 upper stage. They use these cold gas thruster in order to keep the JWST in the field of view of the stationary camera.
safe bronze
Shiny
Also space is beautiful
ornate marsh
it has an extremely large dynamic range though
so you either have a black background or a washed out foreground
cerulean thorn
shiney!
modest dune
last shadow
its taking longer and longer.. still 25 days I think?
modest dune
🥳
wispy sun
safe bronze
Yay's screenshot is brighter 
modest dune
DarkReader addon probably tweaking it lol
last shadow
i only notice the yellow is different, iron' s looks more like the mods yellow
aand yay's like starwar's yellow
wispy sun
I'm on mobile that's why
calm flint
Are we there yet?
thorn musk
irons is more an orangey yellow, mod yellow is between them I think
safe bronze
Does the Pareto principle apply here?
old charm
Does the Pareto principle apply here? <:engithink:800737127121551380>
Given that it’s roughly an exponential/hyperbolic trajectory, and that’s what the Pareto principle describes iirc, I would say so
thorn musk
ngl theres a missed opportunity here
woah-oh we're halfway there
woah-oh living on a prayer
take my hand we'll make it I swear
wooooooooah-oh :P
old charm
🍋 and a 🍐
thorn musk
woah-oh, webb is gonna stare
brave coral
Switches that should have indicated that the cover rolled up did not trigger when they were supposed to. However, secondary and tertiary sources offered confirmation that it had.
noble quarry
🎵 solar shield, it'll unfurl I swear!
wispy sun
brave coral
next up: tensioning
wispy sun
Good luck team
reef sequoia
Phew, that was the step I was by far the most stressed over. That's where it ripped in 2018!
red sail
next up: tensioning
The tension rises!
plucky merlin
The sunshield is about half-deployed now. The next two days will be spent largely on tensioning all five layers
noble quarry
that's a lot of single-point failures passed, then
autumn sierra
Somebody said like 200+? Have we passed like 170 because that's how many bolts had to work on the solar shield? 💦
modest dune
ornate marsh
is the the level on the Hoover Dam?
plucky merlin
JWST technicians preparing to unfurl the sunshield
eternal oar
my fat ass for a split second thought "oh thats a lot of fries" iawdbuilawiwbladbilawdhilbawdawdhbilwadJ
bold bronze
lol
wispy sun
safe bronze
To first get a better idea of how it behaves in space
wispy sun
translation: "we're nervous about it not working so we're double-checking everything", probably
brave coral
microsopic rip widens
noble quarry
*microsopic rip widens*
repositions JWST to weld the rip with the solar wind
carmine olive
Simultaneously, the deployments team is working to make sure motors that are key to the tensioning process are at the optimal temperatures prior to beginning that operation.
seems like a "we're nominal but we can shave off margin by just waiting for things to cool down a bit"
noble quarry
> Simultaneously, the deployments team is working to make sure motors that are k...
definitely no reason to rush things now
carmine olive
zero chance they will rush things
reef sequoia
Let's not get go fever
noble quarry
Webb ground controllers: chill
JWST: chill
All of us here: chill
😛
reef sequoia
Chill with the puns, dude!
noble quarry
JWST: 🎵 "Well it's cold cold cold, cold inside / Darker in the day than the dead of night / Cold cold cold, cold inside"
plucky merlin
> Simultaneously, the deployments team is working to make sure motors that are k...
Waiting for things to heat up, actually. They specifically warm up lots of their actuators before they operate them
wispy sun
brave coral
the teeeennnssiiooonn
brave coral
AAAAAAAAAA
calm flint
We'll be fine as long as we stay away from Mars.
That's where the ripping & tearing occurs.
brave coral
your galaxies are HUGE! that means HUGE photos. study and catalog!
eternal oar
this upgrade is going to boost my significant data production so much!
cerulean thorn
the tension at webb team is probably much bigger than the tension at webb 'scope
old charm
What’s the conversion factor between dramatic tension and Newtons?
cerulean thorn
hmm... 1.21 jigacochranes per warp factor squared by number of newtons
old charm
microscopic tears widen
cerulean thorn
those are some very fancy courtains
I could use some for my room as well when I'm gaming in mid day
glad mist
I’m sure they are available for purchase.
reef sequoia
ROFL, got the science kiss of death
brave coral
goooooood
noble quarry
instrument radiator is reading ~79K, so the sunshield is doing its job!
wispy sun
I didn't know that below absolute zero was a thing
safe bronze
That's a ~, not a -
plucky merlin
Twitter
carmine olive
brave coral
photos WHEN?
carmine olive
of the sunshields? sadly, never
ornate marsh
we should launch a telescope to get a picture of JWST
brave coral
smh how much could it cost to paperclip a webcam so we could look at the sunshields
carmine olive
you gotta light up the james webb then
brave coral
but i meant of deep space
ornate marsh
it has to get to L2 first
it's still 20 days out
then it has to go through calibration
brave coral
i believe you, but also it seems like it should be able to take pictures before that
ornate marsh
which could take a couple months
carmine olive
I think the james webb should have had a single camera that detached, had an led light on it, and would take a single picture of the james webb and then transmit it to the james webb and then have it just float away
safe bronze
Cubesat companion cam?
carmine olive
yea exactly
but then like
just have it float away it doesn't need any propulsion
power gen (battery orsmth)
doesn't need any long-distance communication
safe bronze
What if we just hold up a mirror?
ornate marsh
build a starshade with a mirror so we can take a selfie and image exoplanets!
brave coral
what if there's another space telescope out there at L2, left by previous civilizations or aliens
noble quarry
what if there's another space telescope out there at L2, left by previous civili...
we'd probably have seen it by now
carmine olive
can we see the james webb
noble quarry
well, in some wavelength, yes, I think so
carmine olive
better question, how much money would you have to spend to see the james webb in L2 for yourself
carmine olive
until we have pictures back I bet no one is celebrating too hard
noble quarry
until we have pictures back I bet no one is celebrating too hard
should happen at the end of deployment
so, another ~10 days
they won't be science-quality images, of course, but they'll prove that all the imaging systems are functional
carmine olive
pictures of things that hubble has also taken pictures of I think?
safe bronze
better question, how much money would you have to spend to see the james webb in...
Can't find too much info... With the massive sunshield now deployed it might be possible to see it with a small telescope. Probably depends on how it's aimed though, given the shield is basically a mirror
noble quarry
Can't find too much info... With the massive sunshield now deployed it might be ...
it should always be oriented with the shield facing Earth, so it ought to be decently easy to spot, given it will be perpetually illuminated
ornate marsh
depends on what counts as "see"
it's tiny and far away, if you want to see it as more than a dot you need a massive telescope
hmm, maybe not that massive, "only" about 40 meters
ornate marsh
yeah, seeing it at all won't be too bad
noble quarry
but, yeah, properly imaging it with more than a few pixels will require something a bit larger
ornate marsh
hmm, magnitude 13.8, you can spot that with a 30 cm telescope
ornate marsh
+1.5 magnitude
4 times dimmer
but this was in the process of opening the sunshield, so it will get brighter from that
noble quarry
it's a good bet there will be a lot of telescopes pointed at it once it reaches a stable orbit
Hubble will be jealous
hmm, can we point Hubble at JWST?
maybe it'll be too close
ornate marsh
not sure why we couldn't, although it would have to spin faster than normal to keep pointed
noble quarry
ah, true
well, it'd be very cool if NASA did the calculations and decided it might work
ornate marsh
hmm, HST is 2.4 meters, it will also only see a dot
noble quarry
oh, well, we've pointed the Hubble at the moon
ah, hmm
HST's resolution at the moon is ~60m
so, yeah, it definitely will just see a dot
ah well
ornate marsh
the shortest wavelength I can find for HST is 115 nm, at that wavelength you can resolve it at 8 meters
noble quarry
the sunshield is ~20x15m, so you'll get a half-dozen pixels 😛
safe bronze
not sure why we couldn't, although it would have to spin faster than normal to k...
If it doesn't work a Hubble-like spy sat can probably do it
noble quarry
If it doesn't work a Hubble-like spy sat can probably do it
maybe one of those is doing that right now ...
ornate marsh
oh, stay pointed
the collector size is the limiting factor in angular resolution, so a Hubble-like spy sat would be limited the same way
safe bronze
Yes, but it can definitely track
noble quarry
the collector size is the limiting factor in angular resolution, so a Hubble-lik...
of course we have better-than-HST spy sats now
brave coral
I'm pretty sure the Hubble can spin fast enough to track james webb
why wouldn't it be able to?
it can track the moon
safe bronze
It's probably fine then
brave coral
so its sun shield would be facing us, but it orbits L2. is there any angle where we could see beyond the sheld?
ornate marsh
no, the whole point of the shield is to block us and the Sun
it's around L2 so it can always do both at the same time
old charm
Draw a ray. Put the sun at one end, Webb at the arrow of the ray, and the earth close to it.
noble quarry
so its sun shield would be facing us, but it orbits L2. is there any angle where...
only it can see beyond its shield
old charm
Webb “orbits” the arrow, and always points in the same direction, no way to see around it since it’s always pointing away
brave coral
i don't understand the argument there, max. for example if the Webb was really tall, you'd see the top if the Webb was just a few degrees around l2. Webb is flat, but I think there would be some orbit around l2 that would bring it out far enough that we could see around the shield
old charm
The point is that they’re practically collinear
Just like how the moon is tidally locked, you’ll only ever see the little bits around the edge as it drifts slightly, never any significant amount of the back side
brave coral
well, Webb is a lot closer to us than the sun so any up down motion would be more significant to us than the sun
ornate marsh
The telescope will circle about the Sun-Earth L2 point in a halo orbit, which will be inclined with respect to the ecliptic, have a radius varying between about 250,000 km (160,000 mi) and 832,000 km (517,000 mi), and take about half a year to complete.
that's actually quite far from L2
brave coral
btw I don't really think you could see past the shield, I just don't think that line of reasoning brings us there
safe bronze
> The telescope will circle about the Sun-Earth L2 point in a halo orbit, which ...
Add the distance to L2 to get the angle, then compare that to a model of the telescope :)
ornate marsh
if that's 750,000 km perpendicular to the Sun-Earth line, that's an angle of 26 degrees
plucky merlin
but, yeah, properly imaging it with more than a few pixels will require somethin...
Nobody on Earth, even professional observatories, will be able to "resolve" it (image it in > 1 pixel resolution). However, all telescopes including amateur telescopes should continue to easily be able to see the JWST as a point of light if they know where to look.
ornate marsh
part of the distance is parallel to the line though, so that's just the maximum possible angle
plucky merlin
The size of the JWST on its longest axis is 20 meters. At a distance of 150,000km that is an angular size of only 0.002750 arc-seconds
You also won't be able to see the dark side of the telescope, because one of the main reasons it was positioned at the L2 with the size of sunshield it has is so that it is always blocked from the thermal radiation coming from the Earth
ornate marsh
the 30-Meter Telescope in theory could, but since it's on Earth it has to deal with seeing, so in practice it can't
plucky merlin
the 30-Meter Telescope in theory could, but since it's on Earth it has to deal w...
"At a wavelength of 1 μm, the 30 m diffraction limit is 0.007 arcsec." It can't resolve 0.002750"
plucky merlin
Oh, my bad
ornate marsh
quick search says the shortest wavelength it would be able to see is 310 nm, which is 0.00213"
plucky merlin
quick search says the shortest wavelength it would be able to see is 310 nm, whi...
Thank you, I'm impressed by that resolving power
brave coral
ok, assuming that JWT was 26 degrees above the horizontal, with solar shield pointed straight back, and the thin side of the shied blocking it from earth, we could see the telescope if it was 20 meters tall at the center. its 8 meters tall.
plucky merlin
James Webb Space Trigonometry?
brave coral
hehe
short loom
Super, Hexagons
safe bronze
cerulean thorn
joking aside, that is pretty much a gamma ray burst from pulsars(I think?)
there are flashes of radiation so powerful that they would kill anything in several lightyear radius... if there was anything alive there
ornate marsh
usually from the collapse of a star into a black hole, but sometimes from two neutron stars merging
they're one of the most energetic events we've observed, easily visible from billions of light years away
safe bronze
There's even a livestream
https://www.youtube.com/watch?v=-EnlaXnFcGs
reef sequoia
Wow that's fast!
wispy sun
hype
reef sequoia
Gogogogogogogo
reef sequoia
Dang it, I got a work call so I missed the confirmation
brave coral
oh yeah it needed that to take pictures. take pictures!
wispy sun
I think that's success?
the tolerances in the mirror segmenting parts are pretty tight
cerulean thorn
I wonder if the telescope has extra cameras
I mean, a tiny LED for light and a smarphone camera would be just a few grams
would be so nice to see stuff actually happening, not just telemetry from measurement instruments
noble quarry
I wonder if the telescope has extra cameras
it does not; no hazardcam-like instruments unfortunately
modest dune
I wonder what % of the light the secondary mirror's supports block
I assume it doesn't much matter since the focal length being at infinity means each part of the primary is essentially seeing the same image
topaz gorge
I assume it doesn't much matter since the focal length being at infinity means e...
it also would only have to rotate slightly to counteract any blockage
wispy sun
1.5mm tolerance and a length of 25ft per arm makes for something like 0.02% tolerance
brave coral
I assume it doesn't much matter since the focal length being at infinity means e...
yeah the blocking matters much less than you'd expect. when I take my 8' dobby out, you can put your hand in front of the telescope and it wont noticeably affect the image. and a hand is huge in comparison to the secondary mirror!
wispy sun
is that an effect of the effective area being shrunk a lot from the large light-gathering surface or something?
brave coral
the image does get darker if you block a lot of the aperture. but it doesnt look like there's an out of focus hand in your image as if it was a camera
old charm
Think about how far you have to travel for the horizon to look different
The horizon looks the same for quite a distance around you
So by blocking out some of the area around you, you still have plenty of spots to get an accurate picture of it
modest dune
any light reaching the telescope from its effectively infinite focal length can arrive anywhere on the telescope and form the same image just at a higher or lower photon count
old charm
You don’t need to get a photo of the horizon from every point in a 10 foot radius around you to get an accurate representation of it
wispy sun
So it's kinda like each section gets the same image?
brave coral
one way to think about it is the hand or secondary mirror or whatever is right next to the aperture is so out of focus that it just becomes a blur across the whole image. the blur is so spread out its not noticable
old charm
So it's kinda like each section gets the same image?
Yup!
brave coral
if you're wayyy out of focus you can actually see the secondary mirror and the supports, here are some images i found on google of someone trying to focus onto venus
https://i.stack.imgur.com/N3ZeI.png
https://i.stack.imgur.com/ZPmGu.png
https://i.stack.imgur.com/ZXYC1.png
https://i.stack.imgur.com/yPnXL.jpg
in the first image, the mirror and supports are somewhat in focus and venus is way out of focus
wispy sun
twinkle twinkle little star venus
old charm
Venus wouldn’t twinkle as much!
Since it can be resolved better by the eye than pinpoint stars, it’s less visually affected by atmospheric turbulence
thorn musk
they're one of the most energetic events we've observed, easily visible from bil...
if im not mistaken, the most energetic events are black hole mergers by a country mile
you know its energetic when the energy expenditure is measured in solar masses :P
first one was a combined mass of 60 solar, expended 3, 5% conversion
eternal oar
imagine being close enough to one of those mergers to be able to see the distortions
thorn musk
id imagine youd stop existing very quickly from tidal forces
brave coral
i did some mathy on this video (from the wikipeida gravataional waves article)
https://www.youtube.com/watch?v=Zt8Z_uzG71o
I estimate the images of these black holes have a radius of 1 cm and are 50 cms from my face. the web site the video is from says both black holes are about 30 solar masses. wolfram alpha says that the radius of a black hole with 30 solar masses is 88600 meters. therefore, we can estimate that the video is taken about 4,430,000 meters from the black holes. since there are 2 black holes at 30 solar masses each, we can calculate the acceleration of body 4,400 km distant from 60 solar masses: 4 * 10^8 m/s^2, or about 1 million times earth's gravity.
so yeah, you'd be crushed just from the force of orbiting these black holes. tidal forces would be much, much less. (on the order basically being exactly 0.
thorn musk
I didnt do any math
if youre close enough for visible distortion, youre close enough to be affected by that distortion
brave coral
im sure you didnt, i just did it for personal interest
well, you could use for example a telescope to view the distortion from far away
brave coral
no i calculated tidal forces. it was in my last sentence
brave coral
you're right about that! i dont think i have the skill the calculate the forces from the merger itself!
thorn musk
its a lot probably
brave coral
the website says
The gravitational waves themselves would not be seen by a human near the black holes (though they would be felt!)
but doesnt elaborate. "certainly be felt" isnt that descriptive, but dying from it seems in the range of possibility
however, I dont buy "you can see it" => "you will be killed by it." that doesnt follow!
besides, at the range we're talking about, you'd be killed just from orbiting the black hole. we dont need tidal forces!
thorn musk
however, I dont buy "you can see it" => "you will be killed by it." that doesnt ...
considering that the frequency of the waves hit audible ranges and the power during that exceeds the brightness of the universe?
brave coral
not really interested in continuing. i only wanted to share those numbers because i thought they were interesting
ornate marsh
if im not mistaken, the most energetic events are black hole mergers by a countr...
Something like 1000 times more energetic, yeah
thorn musk
honestly you could estimate how much energy hits you by working out what area of the "sky" you cover at that distance and divide 3 solar masses by that
thorn musk
i did some mathy on this video (from the wikipeida gravataional waves article)
...
ill round up your distance to 4.5Mm and call the average person a 1m2 square, at that distance you would have a sphere with a surface area of ~2.54x10^16
so you divide the energy equivalent of 3 solar masses by that
(6x10^30 kg) / (2.54x10^16 m2) = ~2.36x10^14 kg/m2
so yeah, I think you die :P
for context, atomic bombs release total energy in the region of grams
so now the question is whats the relative effect of a given amount of gravitational energy vs other types :P
ornate marsh
for context, atomic bombs release total energy in the region of grams
A 21 megaton bomb destroys 1 kilogram, for comparison
thorn musk
I got it at around 1 gram not 1 kilo
based on a quick search
either way its magnitudes
ornate marsh
Hmm, from what I can find a ton of TNT is 4.184 GJ, and a kilogram by E=MC^2 would be 9e16 J, which works out to 21 megatons
thorn musk
mmk, so youre looking at ~10^12 megatons of TNT in gravity form :P
per m2 at that range
eternal oar
so what you are saying it thats a no go
brave coral
you'd be dead just orbiting those things even if they werent colliding, so yeah
modest dune
How it started- https://www.youtube.com/watch?v=JypEu99RXgY
How it's going- points further upward 
modest dune
https://blogs.nasa.gov/webb/2022/01/05/secondary-mirror-deployment-confirmed/
“This is unbelievable…We’re about 600,000 miles from Earth, and we actually have a telescope.” really sticks with me somehow
calm flint
Meh, not even mentioning radio telescopes.
noble quarry
https://pbs.twimg.com/media/FIZ4gRHXoAAfrQW?format=jpg&name=medium
oh, no, it's the Galactic Empire Imager
noble quarry
mmk, so youre looking at ~10^12 megatons of TNT in gravity form :P
Einstein wins again
ornate marsh
wispy sun
safe bronze
lol, same
noble quarry
https://blogs.nasa.gov/webb/2022/01/06/webbs-specialized-heat-radiator-deployed-...
cool!
carmine olive
apparently james webb can photograph things that have only 1 photon per second of light hitting the mirrors
noble quarry
makes sense; just use a-few-hundred-second exposure times and you've got plenty of photons!
wispy sun
Typical exposure tIme is one month I think
noble quarry
Typical exposure tIme is one month I think
so many photons!
brave coral
for comparison, one human eye has half a billion photons per second enter it
wispy sun
carmine olive
I think it depends on how bright it is
brave coral
Pertinent https://blogs.nasa.gov/webb/2022/01/06/why-doesnt-webb-have-deployment...
interesting!
noble quarry
I guess I can see feel the reasoning there
brave coral
hehe
thorn musk
I agree cameras are more effort than theyre worth but I disagree with the reasoning - they would be useful for spotting issues that a specific-point sensor would miss
thorn musk
I think a lot of people lump that under touch
modest dune
yup
thorn musk
also tbh its more than that, because it still happens with fake limbs
super interesting
noble quarry
https://en.wikipedia.org/wiki/Proprioception
"I feel dead people" 😛
thorn musk
I wonder if you can see photos develop in real-time since the capture time is a month
old charm
I imagine it’s like doing progressive refine with a render in Blender
noble quarry
probably, but it's unlikely they'll release them like that given the post processing that's typically required
old charm
It’s basically the same as going into photoshop and doing the thing that takes the median of the set of images iirc
noble quarry
I imagine it’s like doing progressive refine with a render in Blender
"Look! This week, these dots got brighter!"
old charm
It’s basically the same as going into photoshop and doing the thing that takes t...
(Same as what they do in astrophotography I mean)
thorn musk
cant wait to find out the whole time the sky has infrared text saying "kilroy was here"
wispy sun
"Look! This week, these dots got brighter!"
woah, pixels!
safe bronze
cant wait to find out the whole time the sky has infrared text saying "kilroy wa...
We still have like 5 months to make this happen!
noble quarry
woah, pixels!
SNR increased to 4.51 from 4.5 this week!
modest dune
cant wait to find out the whole time the sky has infrared text saying "kilroy wa...
Obligatory
I'm still betting on "What the-- HOW could these galaxies have formed this early, this apparent distance away?!"
carmine olive
I wonder if you can see photos develop in real-time since the capture time is a ...
would be a cool desktop background
wispy sun
I think I might make a webhook to automatically post new blog posts
modest dune
I think I might make a webhook to automatically post new blog posts
be very very careful with those; they can bypass the Everyone ping restrictions.... (dunno if you were here for some of the incidents)
brave coral
did we ever find out if @ everyone pings everyone or just the thread members?
wispy sun
don't worry, I'll only post the url and also validate it beforehand
modest dune
I could science it elsewhere
safe bronze
lol
wispy sun
help, now I'm thinking of ways to bypass that
safe bronze
I was in a server with a few hundred people and no restrictions on everyone pings... Until yesterday
Someone used it
modest dune
until you left, or until they cracked down on it? :P
brave coral
i'll test it brb
safe bronze
They quickly fixed that mistake, lol
safe bronze
Woo, web scraping
wispy sun
hmm
brave coral
according to my tests, @ everyoning does not ping people not in the thread
wispy sun
ahhh, familiar old nodejs
brave coral
like an old friend
wispy sun
brave coral
once you do this share how it works in #programming , I've never made a webhook and i dont know if its hard or not
safe bronze
Can a webhook post in threads though?
wispy sun
can you make one and share the endpoint with me? (I don't have admin)
brave coral
id hope so
bold bronze
Webhooks/bots not working in threads is a feature IIRC
I remember someone asking about it in the bot developers Q&A when threads were announced
Can't remember what the exact reasoning was though
brave coral
wait, do webhooks not work in every channel? i dont even understand
from discord's documentation:
Webhooks can send messages to threads by using the thread_id query parameter. See the execute webhook docs for more details
safe bronze
Ah, so it can be changed from the webhook side afterwards I guess. Will set one up for #offtopic
rain oracleBOT
safe bronze
woo?
carmine olive
have it check every minute and only post new articles it hasn't posted yet that were posted in the last five minutes
safe bronze
lol
rain oracleBOT
ornate marsh
I wonder if you can see photos develop in real-time since the capture time is a ...
if it's a composite, probably
if it's a month-long exposure not really
gotta collect all your electrons before you count how many you have
old charm
same difference when it's digital really
wispy sun
prepare yourself for [insert hour]:10
old charm
you're adding up a bunch of images at the end of the day, just depends on how much you're dividing the result by
wispy sun
the cronjob should run then
rain oracleBOT
wispy sun
works fine when manually triggered 👍
brave coral
ornate marsh
same difference when it's digital really
uh, kinda, I guess it comes down to if you wait until the end to count how many photons you received or if you break it up into smaller exposures
carmine olive
comes down to how the collector physically works
if it's collecting individual photos I'd be willing to be that it's all digital
brave coral
in planetary astrophotography you usually want an exposure length as long as possible to reduce noise. but longer exposure can be blurry due to tracking errors and atmospheric conditions. probably the JWST has top tier tracking and no atmosphere problems, so they'll likely do a long exposure. a month long exposure seem crazy to me though. who knows!
carmine olive
doing some research
It is possible to read the pixels in a Webb detector more than once before resetting them
brave coral
nasas site says
These values are for a signal to noise of 10 and a series of 10 exposures of 1000s each.
which is about 16 minutes
ornate marsh
getting the darks for a month-long exposure would be pretty boring
"what's JWST doing now?"
"spending a month taking a picture with the shutter closed"
noble quarry
getting the darks for a month-long exposure would be pretty boring
presumably they only need to do that ~once during the calibration phase
hopefully nothing should drift once everything is stably chill
ornate marsh
yeah, but if you're going for month-long exposures that's still a month spent gathering it (multiple, as they're usually averaged)
as opposed to if they're kilosecond exposures, you can get that done in an hour or so
noble quarry
certainly, but I'm assuming they'll be doing some kind of absolute calibration so that in the absence of anything unusual, they won't need to take very long dark frames
gotta maximize the science photons it sucks up!
ornate marsh
they're typically as long as the exposure is, since the goal is to find out how much of a charge is passively accumulated in the CCD over the duration of the exposure
so you can subtract that from the final image
plucky merlin
The hot pixels/noise being subtracted out with dark frames is usually temperature-dependent
As long as the temperature stays the same and they're using expected exposure lengths, I'll bet they don't have to take dark frames nearly as often as everyone on the ground has to
ornate marsh
probably not, but they still need to do it at least once
although thanks to thermoelectric coolers ground-based CCDs can have pretty consistent temperatures too
noble quarry
although thanks to thermoelectric coolers ground-based CCDs can have pretty cons...
yep, we usually only take dark spectra for the (CCD-based, thermoelectric-cooled) x-ray detectors that my group uses at the start of an experimental run
rain oracleBOT
wispy sun
THERE WE GO
last shadow
now u dont have to
brave coral
will it post every time, even if there's nothing new?
wispy sun
nope- it posts stuff after the previous most recent post, as indicated by the url
now, the downside is that if there's two posts in a day it won't post the second one
but I'll figure that out
oh wait, that was the old approach- the new approach is just to keep a set of already-posted links
brave coral
what about writing all of the posted urls to a file and only posting the ones that arent in the file. oh good
rain oracleBOT
wispy sun
noble quarry
https://jwst.etc.stsci.edu/workbook.html
nothing loads there for me
wispy sun
oops, try https://jwst.etc.stsci.edu/
noble quarry
ah great!
brave coral
every default exposure i could find is less than 10 minutes
oh i found a default exposure at 14 minutes
so that seems to be around the order it
oh lord this documentation page is a rabbit hole https://jwst-docs.stsci.edu/understanding-exposure-times
rain oracleBOT
brave coral
its aliiiiiive
plucky merlin
Nice bot work, whoever that author is!
modest dune
@wispy sun :P
safe bronze
I chose a pfp for that webhook with the mirrors folded... Does this mean I'll have to update it?
brave coral
i didnt look at it close and thought it was a book >>
safe bronze
I'll take the shoobs as a yes. Here you go, changed it to this:
Seems it doesn't change retroactively though
brave coral
perfect. this gives us historical lookback
safe bronze
Tbh it should do that before announcing the stage has happened then :P
I think you can do that on the programming end too...
But then you'd also need to get the right trigger from the article tiles
modest dune
:þ
noble quarry
there's only one more interesting deployment left, though :d
you should just change it to full deployment and hope it doesn't jinx anything
wispy sun
You know what I said about there not being an RSS feed? https://blogs.nasa.gov/webb/feed/
brave coral
lmfao outskilled
wispy sun
the sunshield provides a level of protection that would be on the order of more than SPF 1 million if it were sunscreen lotion
LOL https://www.youtube.com/watch?v=aUGD9YcV5qo
brave coral
spf 1 million gets you to 73 kelvin lomaooo
old charm
News: shade protects you from the sun, who knew?!
carmine olive
i feel like a lot of things are on the order of very high SPF cause all you need is smth that blocks light
brave coral
lmao i was thinking the same thing
rain oracleBOT
reef sequoia
FULLY DEPLOYED
modest dune
:D
reef sequoia
All deployments are complete, the telescope is alive!
... At least, after they calibrate it.
noble quarry
WEBB-CRUISER OPERATIONAL!
safe bronze
Blog article incoming in 1 minute?
rain oracleBOT
brave coral
WE DID IT
last shadow
Blog article incoming in 1 minute?
1 + 26 close enough
safe bronze
That's just nasa being slow :P
brave coral
This is the first time a NASA-led mission has ever attempted to complete a complex sequence to unfold an observatory in space
its always funny when someone puts a bunch of qualifiers
have there been missions that did a complex sequence to unfold an observatory in space that were not lead by nasa?
have there been missions led by nasa that attempted a complex sequence to unfold non-observatories?
modest dune
have there been missions that did a complex sequence to unfold an observatory in...
I feel like you'd like the Let's Simplify card in the Fluxx cardgame
brave coral
"simplicity is the ultimate sophistication"
quaint plaza
FULLY DEPLOYED
Ayyy yo celebrate
young locust
> This is the first time a NASA-led mission has ever attempted to complete a com...
Everything is a first with enough qualifiers
brave coral
everything is a first (with enough qualifiers)
eternal oar
everything is a first (with enough qualifiers)
first person EVER in the history of this specific discord to reply to THIS message in THIS manner
I am very proud of this achievement
eternal oar
FULLY DEPLOYED
brave coral
first person EVER in the history of this specific discord to reply to THIS messa...
This is the first time a j5drops-led mission has ever attempted to complete a complex reply to make a joke in this thread
plucky merlin
FULLY DEPLOYED
So am I
brave coral
🎵 you're fully deployed, and so am I 🎵
rain oracleBOT
brave coral
weekly blog updates 🤔
modest dune
The Ariane 5 program also selected the best components for Webb based upon pre-flight testing. For example, for the Webb-designated rocket, the program used a main engine that had been especially precise during testing. "It was one of the best Vulcain engines that we've ever built," Albat said. "It has very precise performance. It would have been criminal not to do it."
from https://arstechnica.com/science/2022/01/all-hail-the-ariane-5-rocket-which-doubled-the-webb-telescopes-lifetime/
and apparently the small error that did happen was just getting it closer to the target velocity (which had to be undershot by the rocket as the satellite's thrusters couldn't reduce its speed)
brave coral
oldish news but one i hadnt read. apparently they'll have plenty of fuel, due to an accurate launch and initial burn
wispy sun
20 years last they said
modest dune
https://blogs.nasa.gov/webb/2021/12/29/nasa-says-webbs-excess-fuel-likely-to-ext...
it's interesting how much higher res this image is than the space seemingly allocated to it on that page https://blogs.nasa.gov/webb/wp-content/uploads/sites/326/2021/12/Webb-launch-51776807789_116eeb834a_o-768x983.jpeg
brave coral
that's pretty common
modest dune
inefficiency! ...but yeah :P
brave coral
simplicity!
safe bronze
It's already scaled down though:
https://blogs.nasa.gov/webb/wp-content/uploads/sites/326/2021/12/Webb-launch-51776807789_116eeb834a_o.jpeg
2607x3337
rain oracleBOT
modest dune
suddenly reminded of https://www.youtube.com/watch?v=oyfB63Y2E_c
particularly at 1:10
brave coral
standby for mirror alignment...
old charm
isnt that gonna take like 5 months?
#924064588360716319 message Your answer lies within :p
eternal oar
Mobile does not want to take me to that link one second
noble quarry
mirror alignment for Webb feels very much like a human waking up and progressively twiddling their muscles from fingers/toes on up to shoulders/hips
modest dune
Apparently the resolving power at the longer wavelengths may be limited severely enough to make more distant observations of distinct galactic structures a challenge, despite the ability to handle higher redshift https://www.youtube.com/watch?v=gOpbXBppUEU
the conclusion of the video contains a comparison of the hubble deep field in the visible range with a projection of what Webb would see in the same area
ornate marsh
that a good point, since angular resolution is inversely proportional to wavelength
is directly proportional?
it's harder to see things at longer wavelengths
it's just backwards because smaller resolutions are better
which is how you end up needing something the size of Arecibo (RIP) to do radio astronomy
modest dune
the giant distributed radio interferometry systems online now are crazy
arecibo was more noteworthy at this point for its ability to broadcast -> perform radar scans
ornate marsh
true, the VLA at its maximum reach is 100 times larger than Arecibo was
and that's before you start getting into what you can do with networked telescopes
last shadow
it looks weird
rain oracleBOT
brave coral
wow! that gives an idea on just how slow the initial mirror adjustments are
Each of the mirrors can be moved with incredibly fine precision, with adjustments as small as 10 nanometers (or about 1/10,000th of the width of a human hair). Now we’re using those same actuators instead to move over a centimeter
And we don’t do them all at once. The mirror control system is designed to operate only one actuator at a time.
Furthermore, to limit the amount of heat put into Webb’s very cold mirrors from the actuator motors, each actuator can only be operated for a short period at a time. Thus, those big 12.5-millimeter moves for each segment are split up into many, many short moves that happen one actuator at a time
At full speed, it takes about a day to move all the segments by just 1 millimeter.[!!!]
last shadow
And we don’t do them all at once. The mirror control system is designed to operate only one actuator at a time.
so th ats why its so slow to calibrate
storm viper
looks like something I'd make in KSP
modest dune
Oh, nice, I hadn't seen the alignment tracker.
carmine olive
link?
calm flint
The top pin, I believe.
modest dune
yeah, it's just a part of the page I hadn't seen active
A3 and A6 have since finished it seems
topaz gorge
that's awesome
definitely buying that if they release it
and it actually folds???
damn
noble quarry
and it actually folds???
yes, that was my reaction too! I'm still not entirely clear on how they get the sunshield packed down so tight
topaz gorge
I don't think the shield itself folds
you probably have to remove it before folding
it looks like the shield is clamped into place by attaching it to the rods that are at the corners
the folded version has those rods, but there's nothing attached to them
safe bronze
I think I've seen a video of someone assembling that: yes, the sunshield is added separately after unfolding the rest
noble quarry
ah well
rain oracleBOT
modest dune
brave coral
already! speedy!
wispy sun
The blog bot is down for the moment because the machine that it was running on is old and buggy(graphics/XWayland-wise)