Re: Finally- Next Gen James Webb Telescope set for launch
Posted: Mon Jan 03, 2022 3:26 pm
by Animal
Antknot wrote: ↑Mon Jan 03, 2022 3:10 pm
In very general terms the distance the Earth orbits the Sun determines its speed. To move further away you increase speed, to move closer you reduce speed. Think of the change in the distance traveled (circumference of a circle).
Okay, then explain this. You have seemed to mention a few times that Earth and Webb will be traveling at the same orbit velocity. Webb will just be in a location the earth has not reached yet.
That doesn't seem to be right.
Re: Finally- Next Gen James Webb Telescope set for launch
Animal wrote: ↑Sun Jan 02, 2022 12:11 am
It got 1/2 way to its final orbit in 7 days. but it looks like it will be around day 30 when it reaches the target location. I guess that means it is gradually slowing down as it goes?
Right now its speed is 0.3961 mi/sec. I'll check that in a day or two and see how it compares.
Speed update. Okay, its been around 24 hours and the speed has reduced to 0.3740 mi/second. It is showing to be 22 days away from its final position.
If it loses .02 mi/sec each day, that would mean it would lose .44 mi/sec in speed over the next 22 days, which would bring it to a stop. So, maybe that is what it is doing. Maybe its speed is set to gradually be decelerating until it stops at exactly the right location.
another (boring) speed update. Right now its at 0.3438 mi/sec. Meaning it has slowed another 0.03 mi/sec. I read a scientist guy describe it as if it is coasting slightly uphill.
Re: Finally- Next Gen James Webb Telescope set for launch
Antknot wrote: ↑Mon Jan 03, 2022 3:10 pm
In very general terms the distance the Earth orbits the Sun determines its speed. To move further away you increase speed, to move closer you reduce speed. Think of the change in the distance traveled (circumference of a circle).
Okay, then explain this. You have seemed to mention a few times that Earth and Webb will be traveling at the same orbit velocity. Webb will just be in a location the earth has not reached yet.
Antknot wrote: ↑Mon Jan 03, 2022 3:10 pm
In very general terms the distance the Earth orbits the Sun determines its speed. To move further away you increase speed, to move closer you reduce speed. Think of the change in the distance traveled (circumference of a circle).
Okay, then explain this. You have seemed to mention a few times that Earth and Webb will be traveling at the same orbit velocity. Webb will just be in a location the earth has not reached yet.
Yes. I understand that. Webb will be at point L2. Which means it is about 1.5 million kilometers away from earth (and the sun). It will remain in that respective position to earth as it rotates the sun, meaning it will have to be moving faster than earth since its orbital path is larger than earth's. And the earth will never be any any of the locations of Webb since the earth is closer to the sun than Webb.
Now, explain what you mean when you say they have the same "orbital velocity" and that Webb will be in a location that the earth has not reached yet.
Re: Finally- Next Gen James Webb Telescope set for launch
Antknot wrote: ↑Mon Jan 03, 2022 3:10 pm
In very general terms the distance the Earth orbits the Sun determines its speed. To move further away you increase speed, to move closer you reduce speed. Think of the change in the distance traveled (circumference of a circle).
Okay, then explain this. You have seemed to mention a few times that Earth and Webb will be traveling at the same orbit velocity. Webb will just be in a location the earth has not reached yet.
Yes. I understand that. Webb will be at point L2. Which means it is about 1.5 million kilometers away from earth (and the sun). It will remain in that respective position to earth as it rotates the sun, meaning it will have to be moving faster than earth since its orbital path is larger than earth's. And the earth will never be any any of the locations of Webb since the earth is closer to the sun than Webb.
Now, explain what you mean when you say they have the same "orbital velocity" and that Webb will be in a location that the earth has not reached yet.
You don't understand.
Webb will be in the same orbital path as Earth roughly 93 million miles from the Sun. It will be moving throuh space at the same rate as Earth. It will be located 1.5 million miles from Earth (Earth's orbit is an ellipse not a circle thus approx numbers)
Think of a single lane race track. Webb and Earth will be running laps on that race track. They will be running at the same speed. Webb will be ahead of Earth.
Re: Finally- Next Gen James Webb Telescope set for launch
Antknot wrote: ↑Mon Jan 03, 2022 3:10 pm
In very general terms the distance the Earth orbits the Sun determines its speed. To move further away you increase speed, to move closer you reduce speed. Think of the change in the distance traveled (circumference of a circle).
Okay, then explain this. You have seemed to mention a few times that Earth and Webb will be traveling at the same orbit velocity. Webb will just be in a location the earth has not reached yet.
Yes. I understand that. Webb will be at point L2. Which means it is about 1.5 million kilometers away from earth (and the sun). It will remain in that respective position to earth as it rotates the sun, meaning it will have to be moving faster than earth since its orbital path is larger than earth's. And the earth will never be any any of the locations of Webb since the earth is closer to the sun than Webb.
Now, explain what you mean when you say they have the same "orbital velocity" and that Webb will be in a location that the earth has not reached yet.
You don't understand.
Webb will be in the same orbital path as Earth roughly 93 million miles from the Sun. It will be moving throuh space at the same rate as Earth. It will be located 1.5 million miles from Earth (Earth's orbit is an ellipse not a circle thus approx numbers)
Think of a single lane race track. Webb and Earth will be running laps on that race track. They will be running at the same speed. Webb will be ahead of Earth.
Ok. I thought that's what you have been saying. which is wrong. webb will be 1.5 million kilometers further from the sun than earth.
Re: Finally- Next Gen James Webb Telescope set for launch
Posted: Mon Jan 03, 2022 8:21 pm
by Antknot
Well hell, that’s what I get Tom relying on 40 year old memories instead of looking stuff up
Re: Finally- Next Gen James Webb Telescope set for launch
Posted: Mon Jan 03, 2022 10:13 pm
by CentralTexasCrude
To be honest, I don't care how it's all set up. Just looking forward to some awesome images. Looking back 13 billion years to within a few hundred million years of the Big Bang seeing the first stars "fire up".
Re: Finally- Next Gen James Webb Telescope set for launch
Posted: Tue Jan 04, 2022 12:04 am
by Antknot
Re: Finally- Next Gen James Webb Telescope set for launch
Posted: Tue Jan 04, 2022 12:10 am
by CentralTexasCrude
Re: Finally- Next Gen James Webb Telescope set for launch
Posted: Wed Jan 05, 2022 3:36 pm
by Animal
Today, the webb will unfold its secondary mirror. That's the little one that sits out in front of the big one.
This activity releases the last of four launch locks that holds the Aft Deployed Instrument Radiator (ADIR) in its launch configuration. Releasing the last device allows springs to drive the ADIR into its final deployed position. The first three launch locks were released just after launch to prevent any unwanted strain in the system as the ADIR and telescope cools.
Re: Finally- Next Gen James Webb Telescope set for launch
Posted: Fri Jan 07, 2022 3:43 pm
by Animal
On today's agenda for the Webb:
Port Primary Mirror Wing Begins - This step begins the Primary Mirror deployment phase.
Nominal Event Time: Launch + 13 days (Friday 1/7/22)
Status: Ongoing.
That's the vertical column of mirrors on the right side of the picture.
The deployments team begins planning and operations for the deployment of the left/port (+V2) primary mirror wing from its stowed/launch position into its operational position. This operation deploys and latches the +V2 wing of the primary mirror. Each wing holds three of the 18 mirror segments. This is a motor-driven deployment.
Re: Finally- Next Gen James Webb Telescope set for launch
Posted: Fri Jan 07, 2022 3:47 pm
by Animal
You may find yourself asking....
"Why aren't there camera's on Webb so we can watch these critical deployments as the telescope unfolds?"
"Adding cameras to watch an unprecedently complicated deployment of such a precious spacecraft as Webb sounds like a no-brainer, but in Webb’s case, there’s much more to it than meets the eye,” said Paul Geithner, deputy project manager – technical for the Webb telescope at NASA’s Goddard Space Flight Center. “It’s not as straightforward as adding a doorbell cam or even a rocket cam.”
First of all, Webb is big, undergoes many configuration changes during deployment, and has many specific locations of import to deployment. Monitoring Webb’s deployments with cameras would require either multiple narrow-field cameras, adding significant complexity, or a few wide-field cameras that would yield little in the way of helpful detailed information. Wiring harnesses for cameras would have to cross moving interfaces around the observatory and add more risk of vibrations and heat leaking through, presenting a particular challenge for cameras located on the cold side of Webb.
Then there’s the issue of lighting. Webb is very shiny, so visible cameras on the Sun-facing side would be subject to extreme glare and contrast issues, while ones on the cold, shaded side would need added lighting. 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. This would either require ‘ordinary’ cameras to be encapsulated or insulated so they would work in extreme cold, or development of special-purpose cryogenic-compatible cameras just for deployment surveillance.
Notwithstanding these challenges, engineers mocked up and tested some camera schemes on full-scale mockups of Webb hardware. However, they found that 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.” Engineers can also correlate years of data from ground testing with telemetry data from flight sensors to insightfully interpret and understand flight sensor data.
Re: Finally- Next Gen James Webb Telescope set for launch
Posted: Fri Jan 07, 2022 4:54 pm
by CentralTexasCrude
Thanks for the updates, animal
Re: Finally- Next Gen James Webb Telescope set for launch
Posted: Fri Jan 07, 2022 5:48 pm
by Animal
In case anyone is wanting to put some size perspective to this thing. There are some men in this picture.
Re: Finally- Next Gen James Webb Telescope set for launch
Posted: Fri Jan 07, 2022 5:50 pm
by Animal
Re: Finally- Next Gen James Webb Telescope set for launch
Posted: Fri Jan 07, 2022 5:51 pm
by Animal
Re: Finally- Next Gen James Webb Telescope set for launch
Re: Finally- Next Gen James Webb Telescope set for launch
Posted: Fri Jan 07, 2022 7:05 pm
by Charliesheen
Animal wrote: ↑Fri Jan 07, 2022 3:47 pm
You may find yourself asking....
"Why aren't there camera's on Webb so we can watch these critical deployments as the telescope unfolds?"
"Adding cameras to watch an unprecedently complicated deployment of such a precious spacecraft as Webb sounds like a no-brainer, but in Webb’s case, there’s much more to it than meets the eye,” said Paul Geithner, deputy project manager – technical for the Webb telescope at NASA’s Goddard Space Flight Center. “It’s not as straightforward as adding a doorbell cam or even a rocket cam.”
First of all, Webb is big, undergoes many configuration changes during deployment, and has many specific locations of import to deployment. Monitoring Webb’s deployments with cameras would require either multiple narrow-field cameras, adding significant complexity, or a few wide-field cameras that would yield little in the way of helpful detailed information. Wiring harnesses for cameras would have to cross moving interfaces around the observatory and add more risk of vibrations and heat leaking through, presenting a particular challenge for cameras located on the cold side of Webb.
Then there’s the issue of lighting. Webb is very shiny, so visible cameras on the Sun-facing side would be subject to extreme glare and contrast issues, while ones on the cold, shaded side would need added lighting. 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. This would either require ‘ordinary’ cameras to be encapsulated or insulated so they would work in extreme cold, or development of special-purpose cryogenic-compatible cameras just for deployment surveillance.
Notwithstanding these challenges, engineers mocked up and tested some camera schemes on full-scale mockups of Webb hardware. However, they found that 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.” Engineers can also correlate years of data from ground testing with telemetry data from flight sensors to insightfully interpret and understand flight sensor data.
Great question and great answer.
Re: Finally- Next Gen James Webb Telescope set for launch
Posted: Sat Jan 08, 2022 7:56 pm
by Animal
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.
Re: Finally- Next Gen James Webb Telescope set for launch
Posted: Sat Jan 08, 2022 8:47 pm
by CentralTexasCrude
A week old but interesting. JW deployment from it's capsule. May work for decades, but it will be the last time any human eyes will ever see it again.
Notice the debris floating out as it's deployed. Always something left over from the technicians. Always
Re: Finally- Next Gen James Webb Telescope set for launch
Posted: Sat Jan 08, 2022 10:08 pm
by Animal
This is interesting:
Re: Finally- Next Gen James Webb Telescope set for launch
Posted: Sat Jan 08, 2022 10:17 pm
by Animal
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.
