Re: Finally- Next Gen James Webb Telescope set for launch
Posted: Sat Jan 08, 2022 10:42 pm
by CentralTexasCrude
Animal wrote: ↑Sat Jan 08, 2022 10:17 pm
Its weird. The Webb, right now, is about 650,000 miles away from us. And if you are on the "hot side", the side facing the sun, its about 50 degrees F where the computer stuff is. The average of that side of the big "shield" is 130 degrees F. Now, if you go on the other side of that "shield" it is about -300 degrees F. Just keep that in mind if someone asks you where you want to sit on the next flight.
Closest to the drink carts?
Re: Finally- Next Gen James Webb Telescope set for launch
Animal wrote: ↑Sat Jan 08, 2022 10:17 pm
Its weird. The Webb, right now, is about 650,000 miles away from us. And if you are on the "hot side", the side facing the sun, its about 50 degrees F where the computer stuff is. The average of that side of the big "shield" is 130 degrees F. Now, if you go on the other side of that "shield" it is about -300 degrees F. Just keep that in mind if someone asks you where you want to sit on the next flight.
Closest to the drink carts?
Won't have to ask for ice though.
P.S. And I'm not sure you can say we'll never see it again. Decades from now we might want to put a station at that Lagrange point.
Re: Finally- Next Gen James Webb Telescope set for launch
Posted: Sat Jan 08, 2022 11:47 pm
by FSchmertz
Animal wrote: ↑Sat Jan 08, 2022 7:56 pm
The final mirrors were moved into place today and right now the telescope is fully unfolded. Now, they have about 3 months of calibrating and aligning all of the mirrors. They will individually flex each mirror with actuators from behind to make sure they are precisely aligned with all of the others.
I also learned that one of the reasons why the thing is coasting into position, is because it cannot turn and thrust in the opposite direction because the heat would completely fuck up the instruments. The heat sensitivity of these instruments is mind blowing.
I also learned that the Webb is going to "orbit" the L2 point. In other words, it will be orbiting the sun, but it will also be orbiting L2 in a very small orbit. Sort of like the moon orbits earth while it orbits the sun. I didn't read an explanation of why that is, but i found it interesting.
The complete orbit around L2 takes about 6 months, is apparently similar in size to the orbit the Moon takes around Earth, and keeps it out of Earth's and the Moon's shadow, allowing continuous contact from Earth, unlike Hubble.
Animal wrote: ↑Sat Jan 08, 2022 10:17 pm
Its weird. The Webb, right now, is about 650,000 miles away from us. And if you are on the "hot side", the side facing the sun, its about 50 degrees F where the computer stuff is. The average of that side of the big "shield" is 130 degrees F. Now, if you go on the other side of that "shield" it is about -300 degrees F. Just keep that in mind if someone asks you where you want to sit on the next flight.
Closest to the drink carts?
Won't have to ask for ice though.
P.S. And I'm not sure you can say we'll never see it again. Decades from now we might want to put a station at that Lagrange point.
Maybe. It will be up there probably for a few hundreds of thousand years.
Re: Finally- Next Gen James Webb Telescope set for launch
Re: Finally- Next Gen James Webb Telescope set for launch
Posted: Wed Jan 12, 2022 4:12 pm
by Animal
So, it seems to have pretty much leveled out its speed at around the speed of sound. 0.2 mi per second. That is about the speed it needs to cover the remaining 156,000 mi in the next 10 days. Then it spends 2 or 3 days adjusting its path to bring it to its final resting place at L2. Today they start adjusting mirrors to begin the final calibrations.
Re: Finally- Next Gen James Webb Telescope set for launch
Posted: Wed Jan 12, 2022 11:16 pm
by Animal
Because I know you are all curious how, exactly, they calibrate and align all of these mirrors. Each of the 18 mirrors have 6 actuators that can be used to very very very minutely adjust them and which direction they are reflecting. We are talking about adjustments 1/10,000 the thickness of a human hair. That's more than the fine tuner on your AM dial.
Re: Finally- Next Gen James Webb Telescope set for launch
Posted: Wed Jan 12, 2022 11:23 pm
by CentralTexasCrude
Every technical post for the last several years. "Can we just forget all this techno mumbo-jumbo and just show us the GD photos"? sin-Animal.
Re: Finally- Next Gen James Webb Telescope set for launch
Posted: Wed Jan 12, 2022 11:32 pm
by Animal
CentralTexasCrude wrote: ↑Wed Jan 12, 2022 11:23 pm
Every technical post for the last several years. "Can we just forget all this techno mumbo-jumbo and just show us the GD photos"? sin-Animal.
If they had put me in charge of building Webb, there would have been so many god damn cameras all over it that the NASA launch guys would have been looking at me like Sam Elliot was to those Germans when they got their wagons to the Brazos River.
Re: Finally- Next Gen James Webb Telescope set for launch
CentralTexasCrude wrote: ↑Wed Jan 12, 2022 11:23 pm
Every technical post for the last several years. "Can we just forget all this techno mumbo-jumbo and just show us the GD photos"? sin-Animal.
If they had put me in charge of building Webb, there would have been so many god damn cameras all over it that the NASA launch guys would have been looking at me like Sam Elliot was to those Germans when they got their wagons to the Brazos River.
I can't believe they spent 2 whole episodes talking about crossing that river... and then crossed it in 3 minutes of screen time.
Re: Finally- Next Gen James Webb Telescope set for launch
CentralTexasCrude wrote: ↑Wed Jan 12, 2022 11:23 pm
Every technical post for the last several years. "Can we just forget all this techno mumbo-jumbo and just show us the GD photos"? sin-Animal.
If they had put me in charge of building Webb, there would have been so many god damn cameras all over it that the NASA launch guys would have been looking at me like Sam Elliot was to those Germans when they got their wagons to the Brazos River.
I can't believe they spent 2 whole episodes talking about crossing that river... and then crossed it in 3 minutes of screen time.
You have to admit, though. Whoever thought of writing that scene to play out while that girl played Beethoven on a freaking piano sitting in the middle of a prairie was brilliant.
I liked it when the cowboy says after she finishes, "you know any happy ones?"
Re: Finally- Next Gen James Webb Telescope set for launch
CentralTexasCrude wrote: ↑Wed Jan 12, 2022 11:23 pm
Every technical post for the last several years. "Can we just forget all this techno mumbo-jumbo and just show us the GD photos"? sin-Animal.
If they had put me in charge of building Webb, there would have been so many god damn cameras all over it that the NASA launch guys would have been looking at me like Sam Elliot was to those Germans when they got their wagons to the Brazos River.
Re: Finally- Next Gen James Webb Telescope set for launch
Posted: Sun Jan 16, 2022 4:31 pm
by Animal
So right now the adjustment of the mirrors is still going on. That will take several more weeks.
The Webb is now about 90% of the way to its final orbit in L2. It has 92,000 more miles to go and its speed has slowed down to just a bit more than a commercial airliner. Right now it is moving at around 890 mph.
I know you are all doing the math, so at that speed (890 mph) to travel 92,000 miles, that would take 4.3 days. Yet its not supposed to get there until 8 more days. That's because its still slowing down. "Coasting" into place is how NASA describes it.
Re: Finally- Next Gen James Webb Telescope set for launch
Posted: Sun Jan 16, 2022 7:42 pm
by Animal
In case anyone thinks that adjusting the mirrors on Webb are the same as adjusting the mirrors in, say, your bathroom, watch this:
Re: Finally- Next Gen James Webb Telescope set for launch
Posted: Tue Jan 18, 2022 4:35 am
by peterosehaircut
disco wrote: ↑Mon Jan 17, 2022 12:41 pm wow! Will someone tell Animal Thanks for posting this stuff? I'm so excited about that damn telescope.
You just did a whole bunch of hours ago.
Re: Finally- Next Gen James Webb Telescope set for launch
Posted: Thu Jan 20, 2022 6:17 pm
by Animal
Over 95% of the distance traveled. About 4 more days to go. Its still 37,500 miles away from L2. And traveling at about 500 mph.
Re: Finally- Next Gen James Webb Telescope set for launch
Posted: Thu Jan 20, 2022 10:09 pm
by Animal
So, beginning in 3 days (day 29) the Webb will begin some thrust adjustments to get it into its final orbit. Originally, the Arianne rocket gave Webb just slightly less thrust than was necessary to get it to L2. That is because Webb cannot stop itself by thrusting in the opposite direction. To do that it would have to turn around and expose its optics and structure to the sun which would overheat them and ruin the entire mission.
So, it will use 3 small thrusts. There are three mid-course correction (MCC) maneuvers: MCC-1a, MCC-1b, and MCC-2. This final burn, MCC-2, which inserts Webb into its L2 halo orbit.
Re: Finally- Next Gen James Webb Telescope set for launch
Posted: Fri Jan 21, 2022 12:39 am
by rule34
disco wrote: ↑Fri Jan 21, 2022 12:33 am
Can you PM me more about the thrust adjustments? Thanks.
One to the left, one to the right, and one right down the middle.
Re: Finally- Next Gen James Webb Telescope set for launch
Posted: Fri Jan 21, 2022 3:20 pm
by Animal
26,800 miles to go. Current speed 496 mph.
Re: Finally- Next Gen James Webb Telescope set for launch
Posted: Fri Jan 21, 2022 5:47 pm
by CentralTexasCrude
"Is it there, yet? Let's go with the photos already." sin- someone we know.
Re: Finally- Next Gen James Webb Telescope set for launch
Posted: Fri Jan 21, 2022 5:53 pm
by saltydog
What a fine use of time, money and resources.
Re: Finally- Next Gen James Webb Telescope set for launch
Posted: Fri Jan 21, 2022 5:55 pm
by Animal
saltydog wrote: ↑Fri Jan 21, 2022 5:53 pm
What a fine use of time, money and resources.
i know, right? We could have bought 400 million N95 masks and mailed them out to everyone for a one time use.
Re: Finally- Next Gen James Webb Telescope set for launch