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greenskull 2021-08-21 18:32

James Webb Space Telescope
 
1 Attachment(s)
In November or early December 2021, it is planned to launch the James Webb Space Telescope with a 6.5-meter mirror.
One of the main tasks of the program is the detection of exoplanets, satellites of these planets and the spectral lines of these planets.

[ATTACH]25514[/ATTACH]

Perigee altitude 374,000 km.
Apogee altitude 1,500,000 km.

The estimated launch date has been postponed many times.
The project budget exceeds $ 10 billion.

xilman 2021-08-22 10:24

[QUOTE=greenskull;586208]In November or early December 2021, it is planned to launch the James Webb Space Telescope with a 6.5-meter mirror.
One of the main tasks of the program is the detection of exoplanets, satellites of these planets and the spectral lines of these planets.

[ATTACH]25514[/ATTACH]

Perigee altitude 374,000 km.
Apogee altitude 1,500,000 km.

The estimated launch date has been postponed many times.
The project budget exceeds $ 10 billion.[/QUOTE]Just Wait, Still Terrestrial.

Dr Sardonicus 2021-08-22 13:31

[QUOTE=xilman;586245]Just Wait, Still Terrestrial.[/QUOTE]Reminds me of Denver International Airport (DIA). Design changes by United Airlines during construction and other factors repeatedly pushed back completion. People were saying that the initials stood for "Delay It Again."

The Hubble Space Telescope was originally scheduled for launch in 1986, was delayed by the events of January 28, 1986, was finally put in orbit in 1990, and went into full service after the 1993 mission to install corrective optics to compensate for an improperly-shaped main mirror. It has had several upgrade and repair missions since then, and is not quite dead yet. Its total cost, repair missions and all, is estimated at around $10 billion US.

The James Webb Space telescope was initially scheduled to launch in 2007. The launch was delayed until 2011, then 2014, then 2018, then 2021. Its cost has been estimated at $10 billion US, and it's still not launched yet.

Because its planned deployment is at the Earth-Sun L[sub]2[/sub] Lagrange point, a million miles beyond Earth as seen by Mr. Sun, there will be no service missions. It will have to use fuel to maintain its position, and its fuel supply is expected to run out in ten years or so.

xilman 2021-08-22 14:23

[QUOTE=Dr Sardonicus;586252]Because its planned deployment is at the Earth-Sun L[sub]2[/sub] Lagrange point, a million miles beyond Earth as seen by Mr. Sun, there will be no service missions. It will have to use fuel to maintain its position, and its fuel supply is expected to run out in ten years or so.[/QUOTE]No [B]planned[/B] service missions.

Who knows what young Mr Musk may be able to do by 2035?

ryanp 2021-08-22 19:40

[QUOTE=Dr Sardonicus;586252]Reminds me of Denver International Airport (DIA). Design changes by United Airlines during construction and other factors repeatedly pushed back completion. People were saying that the initials stood for "Delay It Again."[/QUOTE]

That's what they want you to believe... but really, it was delayed so the Illuminati and New World Order could construct their [URL="https://www.denverpost.com/2016/10/31/definitive-guide-to-denver-international-airport-conspiracy-theories/"]secret underground bunker to survive the apocalypse[/URL]!

Dr Sardonicus 2021-08-22 21:58

[QUOTE=ryanp;586276]That's what they want you to believe... but really, it was delayed so the Illuminati and New World Order could construct their [URL="https://www.denverpost.com/2016/10/31/definitive-guide-to-denver-international-airport-conspiracy-theories/"]secret underground bunker to survive the apocalypse[/URL]![/QUOTE]I liked the yarn about there being a secret underground military base beneath DIA. And that it was just one of a whole [i]network[/i] of underground military bases throughout the lower 48, with a whole [i]underground road system[/i] connecting them. I hope the road system functions better than the baggage-handling system at DIA did when operations began.

Then there's the true story about DIA's "demon" sculpture that killed its creator...

greenskull 2021-10-03 18:58

1 Attachment(s)
As of September 2021, the launch is scheduled for 18 December 2021 on an Ariane 5 launch vehicle from French Guiana.

[ATTACH]25833[/ATTACH]

The observatory attaches to the Ariane 5 launch vehicle via a launch vehicle adapter ring which could be used by a future spacecraft to grapple the observatory to attempt to fix gross deployment problems. However, the telescope itself is not serviceable, and astronauts would not be able to perform tasks such as swapping instruments, as with the Hubble Telescope.

Its nominal mission time is five years, with a goal of ten years. JWST needs to use propellant to maintain its halo orbit around L2, which provides an upper limit to its designed lifetime, and it is being designed to carry enough for ten years.The planned five year science mission begins after a 6-month commissioning phase. An L2 orbit is unstable, so it requires orbital station-keeping, or the telescope will drift away from this orbital configuration.

mathwiz 2021-10-13 00:27

JWST has reportedly [URL="https://www.theverge.com/2021/10/12/22722559/nasa-james-webb-space-telescope-arrives-kourou-french-guiana-launch"]arrived safely[/URL] in French Guiana, in preparation for launch...

kriesel 2021-10-13 02:34

Shouldn't that thread title be James Webb Sinkhole for Tax dollars?

Dr Sardonicus 2021-10-13 13:44

[QUOTE=kriesel;590360]Shouldn't that thread title be James Webb Sinkhole for Tax dollars?[/QUOTE]This is new technology. There were bound to be unforeseen problems along the way. Of course the development costs were high.

Now that we've worked those things out, what we need to do is produce a [i]fleet[/i] of space telescopes, in order to get the unit cost down.

xilman 2021-10-13 14:09

Just Wait, Still Terrestrial.

kriesel 2021-10-13 14:22

[QUOTE=Dr Sardonicus;590403]This is new technology. There were bound to be unforeseen problems along the way. Of course the development costs were high.

Now that we've worked those things out, what we need to do is produce a [I]fleet[/I] of space telescopes, in order to get the unit cost down.[/QUOTE]Or do 20 such development projects, just skip treating cancer for a year. [url]https://www.progressreport.cancer.gov/after/economic_burden[/url]
All those unemployed doctors, nurses, radiology technicians etc may not be very effective engineers, machinists, etc. though without a lot of retraining that would take more than a year.

xilman 2021-10-13 14:38

[QUOTE=kriesel;590417]Or do 20 such development projects, just skip treating cancer for a year. [url]https://www.progressreport.cancer.gov/after/economic_burden[/url]
All those unemployed doctors, nurses, radiology technicians etc may not be very effective engineers, machinists, etc. though without a lot of retraining that would take more than a year.[/QUOTE]I believe the technical term is "opportunity cost".

kriesel 2021-10-13 15:37

[QUOTE=xilman;590424]I believe the technical term is "opportunity cost".[/QUOTE]Opportunity cost is a primarily economics term. [URL]https://en.wikipedia.org/wiki/Opportunity_cost[/URL] An opportunity cost analysis informed by college placement office data is why I did not go for a PhD, although strongly encouraged by certain faculty, and employment interviewers seemed quite satisfied with that answer.

It's a multiyear project for an individual to become adequately trained in a technical field as distinct from medical care as optics, aerospace engineering or manufacturing.

Time lags in responding to choices motivated by shifting economic parameters contribute toward irreversibility. [URL]http://perrings.faculty.asu.edu/pdf_papers_Perrings/Perrings_and_Brock_ARRE_(2009).pdf[/URL]

frmky 2021-10-13 19:56

[QUOTE=Dr Sardonicus;590403]Now that we've worked those things out, what we need to do is produce a [i]fleet[/i] of space telescopes, in order to get the unit cost down.[/QUOTE]
There most assuredly will be, or perhaps are, reconnaissance satellites that share some of the technology of the JWST.

Uncwilly 2021-10-13 20:06

[QUOTE=frmky;590482]There most assuredly will be, or perhaps are, reconnaissance satellites that share some of the technology of the JWST.[/QUOTE]Optical recon sats don't really need to. The seeing will become an issue once one goes beyond the KeyHole sats with mirrors the size of Hubble. How much resolution do you want? Just 2 mirrors the size of Hubble can be deployed in a simpler way than JWST and create and effective diameter 3x that of Hubble. Electronic eavesdropping on the other hand.... there are some with antennae reflectors about the size of JWST's sun shield. I wish that had picked up or saved the button for the cover mission that I saw at JPL for that.

frmky 2021-10-13 20:29

Yes, Orion-class satellites are thought to have reflectors larger than JWST's sun shield. But it's not just the large mirrors. The steering system for JWST's secondary mirror seems closely guarded.

Lariliss 2021-10-20 13:13

We are in the era when the finest cutting edge technology is mature enough to be bald with missions.
Numerous tests, engineering refinements and tests again, all the precautions to eliminate any failure.
The projects are confident enough to state the time lines and costs.

And as [B]@Dr Sardonicus[/B] mentions right, there are too many uncertainties for the plans be very precise.
There is uncertainty on any new uncertainties to come across even.

The technology is on rail to go despite the hindrances. It is kind of careful Occam's razor, and I believe it will work.
As it does for the rest.

greenskull 2021-10-20 20:29

NASA plans to launch the James Webb Space Telescope into orbit Dec. 18, 2021:
[url]https://www.nasa.gov/press-release/nasa-readies-james-webb-space-telescope-for-december-launch[/url]

The countdown:
[url]https://www.webb.nasa.gov/content/webbLaunch/countdown.html[/url]

greenskull 2021-10-20 22:38

I kindly ask the moderators please return back the original name of this thread -- James Webb Space Telescope.
And I ask those who distort the name of my themes beyond recognition to refrain from such a destructiveness.
Thank you.

retina 2021-10-21 02:33

We have a conflict.[QUOTE=kriesel;590360]Shouldn't that thread title be James Webb Sinkhole for Tax dollars?[/QUOTE][QUOTE=greenskull;591172]I kindly ask the moderators please return back the original name of this thread -- James Webb Space Telescope.[/QUOTE]There are a lot of currency symbols in the title. Maybe some people can learn something new from those, while also learning about the ₸€₺€$¢¤₱€?

Dr Sardonicus 2021-10-21 03:06

I wasn't being entirely serious in proposing a fleet of space telescopes. I was responding to a previous post which opined that JWST was a waste of taxpayer money.

It occurred to me that cost overruns were a not-unheard-of phenomenon WRT DOD contracts for weapons systems, whose costs over their lifetimes can dwarf those of JWST. And a not-unheard-of justification has been unforeseen technical problems, with an also not-unheard-of argument that, with the design and production problems resolved, the unit price would be lower.

The notion of a "fleet" of space telescopes seemed absurd to me. I failed to consider that the idea might be taken seriously.

greenskull 2021-10-21 09:00

Thanks for returning the original title.

As I wrote earlier, one of the main tasks of this project is to search for exoplanets similar to the Earth and signs of (intelligent) life.
As a follower of the Paleocontact Theory, I am extremely sensitive to the mission of this project.
And I also understand all the profound consequences for humanity that the discoveries of this project will bring.

Dr Sardonicus 2021-11-24 00:04

[url=https://apnews.com/article/space-launches-space-exploration-science-business-europe-3952579f91e46b1d392f8ae40f0f18c1]Launch of new NASA space telescope delayed after incident[/url][quote]BERLIN (AP) - The European Space Agency says the launch of a new NASA telescope to replace the famed Hubble observatory is being postponed to allow experts to check the device for possible damage following an incident at its spaceport in French Guiana.

The ESA said in a statement late Monday that technicians had been preparing to attach the James Webb Space Telescope to a launch vehicle adapter when a clamp band suddenly loosened, jolting the delicate observatory.
<snip>[/quote]

Uncwilly 2021-11-24 00:38

[SIZE="1"][COLOR="White"][SUP]Commentary on probable launch date:[/SUP][/COLOR][/SIZE]
[YOUTUBE]KmddeUJJEuU[/YOUTUBE]

Dr Sardonicus 2021-11-24 17:26

Christmas! [url=https://www.youtube.com/watch?v=g79K-R7xTFo]What could possibly go wrong?[/url] (YouTube video)

Uncwilly 2021-11-24 17:54

[QUOTE=Dr Sardonicus;593774]What could possibly go wrong?[/QUOTE]Well about 4/5's of those were Atlas's (Jon Glenn's ride to space.)
I will see you with [URL="https://www.youtube.com/watch?v=Zvas4x7JYLo"]this[/URL] and raise you with [URL="https://www.youtube.com/watch?v=qFjoPw0CfAU"]this[/URL].

kriesel 2021-11-24 19:24

[URL]https://www.youtube.com/watch?v=7IjgZGhHrYY[/URL]
[URL="http://www.sal.wisc.edu/WUPPE/"]A payload[/URL] the UW-Madison produced missed the [URL="https://en.wikipedia.org/wiki/Space_Shuttle_Challenger_disaster"]Challenger disaster[/URL] by one flight. That is, if it had been scheduled one flight earlier, it would have been lost along with the ship and crew. By being scheduled 1 flight later, it waited 4 years for its first ride, made it up and down twice, 5 years apart, and is [URL="https://onwisconsin.uwalumni.com/on_campus/new-journey-for-uw-space-telescope/"]going to the Smithsonian[/URL] National Air and Space Museum.

Dr Sardonicus 2021-11-24 21:05

[QUOTE=Uncwilly;593779]Well about 4/5's of those were Atlas's (Jon Glenn's ride to space.)
I will see you with [URL="https://www.youtube.com/watch?v=Zvas4x7JYLo"]this[/URL] and raise you with [URL="https://www.youtube.com/watch?v=qFjoPw0CfAU"]this[/URL].[/QUOTE]Thanks! I could probably watch videos of rockets blowing up all day - as long as they didn't involve anyone getting injured or killed.

There was a story about about the Vanguard TV-3 failure - the first US attempt to put a satellite in orbit - that seems to have dropped by the wayside. In the video, you can see the nose cone coming off as the rocket topples over. Apparently the satellite made it to the ground intact, clear of the explosion, and sat there beeping. My mom told me that someone suggested shooting it to put it out of its misery.

When a rocket blows up in flight, that is usually the result of the Range Safety Officer or Safety Engineer sending a radio signal that detonates an explosive charge designed and installed to rip the casing from end to end. This prevents the rocket from going far downrange and blowing up where it might inflict damage or casualties.

There is at least one video of a rocket that actually went up and subsequently nosed straight down and blew up when it hit the gound. I'm not sure why the self-destruct wasn't executed.

[b]EDIT:[/b] Back on topic - let's hope the thing checks out OK after the little oopsadaisy, and launches safely around Christmas.

And that it works as intended...

jwaltos 2021-11-26 03:29

I was following this deployment with interest for a couple of reasons. There's an excellent documentary on the people involved in this project and its intended hopes and aims which is well worth watching. The second is that I lived in this area for a couple of years (in the 80's) while in the Legion and we had to secure the launch area etc.. . At a popular watering hole in Kourou I had the privilege of meeting some rocket scientists along with some other smart people from all over the world including Canada. One specialty of mine was telecommunications so I was able to get an insight into some of the systems in place at the time. As usual, there was always secret service present who did their best to blend in but mannerisms, vocabulary and a few other things tipped their hand. I could only smile as I bought each one of them a drink when I left for the night.

I was going to put this is in the reading section (where it belongs) but while I'm here...
If anyone reads 2600, there's an interesting piece on post quantum cryptography on p.50 of Vol. 38 No. 2.

Xyzzy 2021-12-03 16:15

[url]https://www.quantamagazine.org/why-nasas-james-webb-space-telescope-matters-so-much-20211203[/url]

Uncwilly 2021-12-04 05:23

[XKCD]2550[/XKCD]

Dr Sardonicus 2021-12-22 00:07

[url=https://apnews.com/article/space-launches-science-business-south-america-a516ed51ec609e6cc07b517ec9cb168d]High wind postpones launch of NASA's newest space telescope[/url][quote]CAPE CANAVERAL, Fla. (AP) - Dangerously high wind will keep NASA's newest space telescope on the ground for at least an extra day, with the launch now targeted for Saturday - Christmas Day - at the earliest.

NASA announced the latest delay Tuesday. Upper-level high wind could force a rocket off-course or even damage or destroy it.[/quote]

masser 2021-12-22 00:14

1 Attachment(s)
.

Uncwilly 2021-12-25 07:32

[XKCD]2559[/XKCD]

xilman 2021-12-25 08:10

launch
 
[url]https://twitter.com/joebarnard/status/1474454697150844934[/url]

mathwiz 2021-12-25 13:16

Bon voyage and godspeed, JWST!!

Uncwilly 2021-12-25 14:13

Now begins the month of nail biting as deployments happen.

Dr Sardonicus 2021-12-25 15:48

[QUOTE=Uncwilly;596207]Now begins the month of nail biting as deployments happen.[/QUOTE]There are something like 300 steps, every one of which has to go right (or [i]made[/i] to go right), in order for the mission not to fail before JWST can even begin to make observations.

If all goes well, there may be folks with their nails bitten off up to their elbows.

Uncwilly 2021-12-25 16:05

[QUOTE=Dr Sardonicus;596218]There are something like 300 steps, every one of which has to go right (or [i]made[/i] to go right), in order for the mission not to fail before JWST can even begin to make observations.[/QUOTE]Not quite the full picture. The deployments then allow the commissioning phase to start. All of the mirrors have to be aligned (separate from deployment). The scope has to cool down (even with the sunshade it won't be at operating temperature at the end of the 30 days. And the instruments have to be calibrated. Etc. So, expect 6 months from arrival at the L2 halo orbit before any 'real' data shows up. And these will likely be just a few easy (low exposure time) photogenic targets.

Xyzzy 2021-12-27 16:40

[YOUTUBE]shPwW11MEHg[/YOUTUBE]

tServo 2021-12-27 22:39

My favorite way to keep track of the status of Webb is one of NASA's pages seen below. It has all kinds of neat stuff on it like distance counters, a timeline of the steps it has done/yet to do, and links to animations of what it is doing or about to do.
Check it out!


[URL]https://webb.nasa.gov/content/webbLaunch/whereIsWebb.html[/URL]

tServo 2022-01-01 14:33

Webb's sunshield has been unfurled !
This was a real nail-biter moment as over a hundred components had to work perfectly to
deploy the 5 layers.


Next up is the tensioning of the layers to get them taut so the heat they trap will be radiated properly and efficiently to space away from the telescope.

firejuggler 2022-01-01 18:13

I have seen on twitter a pettition to rename JW(James Webb)ST to BW( Betty White) ST.

I doubt it will get any traction, but thats a nice intention.
tServo : yes I love this website too.

masser 2022-01-01 18:14

[QUOTE=xilman;586256]No [B]planned[/B] service missions.

Who knows what young Mr Musk may be able to do by 2035?[/QUOTE]

NASA is reporting that the launch and first midcourse correction were precise enough that JWST will have enough fuel to last more than 10 years.

Will it be more expensive to build a new JWST+ OR to perform a mission continuance service mission?

I'm guessing JWST wasn't designed to be serviceable in space, so all we can hope for is a little more than 10 years of results from the mission.

Uncwilly 2022-01-01 18:59

[QUOTE=masser;596822]I'm guessing JWST wasn't designed to be serviceable in space, so all we can hope for is a little more than 10 years of results from the mission.[/QUOTE]It wasn't built with the intent of being serviced. But the ring that was used to hold it to the launch vehicle is in a great place for a Mission Extension Vehicle (MEV) to attach. Similar to what is going on in geostationary, a MEV for NGST (the original name), would dock and take over the thrusty bit of the work. In 10 years this should be a well developed field.

Dr Sardonicus 2022-01-01 19:45

[QUOTE=masser;596822]<snip>
Will it be more expensive to build a new JWST+ OR to perform a mission continuance service mission?
<snip>[/QUOTE]I'm assuming a service mission would have to have a human crew. Cheerfully ignoring that we don't AFAIK even have a [i]plan[/i] for such a mission, let alone a system in place to carry it out, the requirements for a service mission to the Earth-Sun L2 point might make it cost more than replacing the telescope.

But I don't know enough about the requirements for such a mission to be sure.

Of course, simply replacing science mission spacecraft near L2 as they crap out could lead to the region becoming so cluttered with "space junk" as to render it unusable for further space missions. I don't know what provisions may have already been made to remove spacecraft from the vicinity as they become incapable of furthering their missions. If present ability to deal with defunct missions at L2 is insufficient, it would become necessary at some point to develop a plan for missions to deal with them. It might not be necessary for such missions to have human crews. That would probably reduce their cost significantly.

In any case, continuing to use L2 for scientific space missions would seem to require a long term commitment to doing the science.

kriesel 2022-01-01 21:06

[QUOTE=Uncwilly;596828]It wasn't built with the intent of being serviced. But the ring that was used to hold it to the launch vehicle is in a great place for a Mission Extension Vehicle (MEV) to attach. ... a MEV for NGST (the original name), would dock and take over the thrusty bit of the work. In 10 years this should be a well developed field.[/QUOTE]For the same total payload mass, an MEV for only the orbit maintenance thrust may be able to add more than another 10 years station-keeping. Robot docking with locking clamps by an autonomous vehicle with a big fuel tank, since it would need to maneuver more mass once docked. JWST ~6200kg alone. The addon could also conceivably carry a software update for JWST for very short range transmission. Even have another ring on its back if it makes sense to consider a second refuel-by-attach. Should not cost nearly as much as JWST did.

[URL]https://jwst.nasa.gov/content/about/faqs/facts.html[/URL] says 5-10 years for JWST as launched.

Conceivably such robot tugs could be used to declutter L2 someday.

[URL="https://www.youtube.com/watch?v=7PHvDj4TDfM"]This[/URL] is a useful explanation/visualization for L1-L5.

Uncwilly 2022-01-01 21:30

[QUOTE=Dr Sardonicus;596835]I'm assuming a service mission would have to have a human crew.[/quote]
False assumption. There is a current MEV in operation at GEO. No crew on board. Changing out instruments is a different thing. But the main issue with the telescope should be fuel.
[QUOTE]the requirements for a service mission to the Earth-Sun L2 point might make it cost more than replacing the telescope.[/QUOTE]A super MEV delivered with a Falcon Heavy would likely run less than $0.5 billion.
[QUOTE]Of course, simply replacing science mission spacecraft near L2 as they crap out could lead to the region becoming so cluttered with "space junk" as to render it unusable for further space missions.[/QUOTE]JWST and other missions "at" L2 and L1 are in orbits around the L point. And as such, there is a huge amount of space in the area. IIRC the orbit JWST around S-E L2 will be larger than the orbit of the moon around earth.

retina 2022-01-01 22:44

[QUOTE=Uncwilly;596843]JWST and other missions "at" L2 and L1 are in orbits around the L point. And as such, there is a huge amount of space in the area. IIRC the orbit JWST around S-E L2 will be larger than the orbit of the moon around earth.[/QUOTE]L2 is fine. L2 orbits are unstable and require fuel to maintain an object there.

So after the fuel runs out the craft will gradually drift away and fall behind into a heliocentric orbit, clearing the area. Other craft have already done this.

Dr Sardonicus 2022-01-02 00:06

Let's see if I have this right:

1) As long as extending the mission of JWST (or other craft near L2) only requires additional propulsion, that could be accomplished with types of spacecraft already being used to extend missions, though requiring more lift capacity to get them to where they're needed.

2) If propulsion to maintain orbit around L2 runs out, the craft will drift clear of the region on its own.

3) If servicing of the vehicle is needed (repair or replace instruments, mechanical components, etc.), a human crew would be required.

Uncwilly 2022-01-02 00:32

[QUOTE=Dr Sardonicus;596852]1) As long as extending the mission of JWST (or other craft near L2) only requires additional propulsion, that could be accomplished with types of spacecraft already being used to extend missions, though requiring more lift capacity to get them to where they're needed.[/quote]More or less, yes. MEV's are new. A Falcon9 could fling one to L2. A FalconHeavy would be able to send a much bigger and complex one out to L2.
[QUOTE]2) If propulsion to maintain orbit around L2 runs out, the craft will drift clear of the region on its own.[/QUOTE]Yes, slowly. L1, L2, and L3 don't hold on to objects the way L4 and L5 do.
[quote]3) If servicing of the vehicle is needed (repair or replace instruments, mechanical components, etc.), a human crew would be required.[/QUOTE]Even if people went there, it wasn't built like Hubble. Hubble was designed to be refurbished (the plan was initially for it to be returned to earth and serviced and sent back up.) The instruments could be pulled out and replaced. The Wide Field Planetary Camera was changed out in the first servicing mission (it was not able to use the CoSTAR system that 'fixed' the other instruments). And now there is yet a newer version of it on board. And without a very long robot arm, getting from the hot side (where the ring is) to the cold side would be difficult to do while not causing problems for the sunshield.

xilman 2022-01-02 10:06

[QUOTE=kriesel;596841]For the same total payload mass, an MEV for only the orbit maintenance thrust may be able to add more than another 10 years station-keeping. Robot docking with locking clamps by an autonomous vehicle with a big fuel tank, since it would need to maneuver more mass once docked. JWST ~6200kg alone. The addon could also conceivably carry a software update for JWST for very short range transmission. Even have another ring on its back if it makes sense to consider a second refuel-by-attach.[/QUOTE]If designed appropriately, The MEV could undock and get out of the way of its replacement, exactly how the Ariane did.

kriesel 2022-01-02 14:57

[QUOTE=xilman;596905]If designed appropriately, The MEV could undock and get out of the way of its replacement, exactly how the Ariane did.[/QUOTE]Yes. It depends on design details whether the grippers reliably unlatch again, power remains to run them, whether economics and component life expectancies favor replacing thrusters and control systems or refueling the first MEV. In critical components it's usual to have nose to nose redundancy. On WUPPE there were nose to nose gearmotors for opening the telescope to view space or closing the main aperture to protect the optics from gases from shuttle attitude control thrusters etc. One could seize solid and if the other worked the telescope still worked. Stacked MEV grippers might be the way to go to ensure release from JWST. Since there are probably at least 3 grippers onto the ring, that ~triples ring grip release failure probability, so some redundancy for release would be valuable; if the gripper won't release the ring, release the gripper from the MEV, sever any electrical connection, the replacement MEV grips on the ring at a different clock angle to avoid the stuck gripper(s). It's less reliable to require release of the first MEV, but reducing the controlled mass by removing the first MEV is an advantage. One can imagine having a grip ring on the first MEV in case of release failure or refuel manuever failure. Second MEV then has more than one way to fulfill its mission. Man years would get spent analyzing different scenarios and probabilities and tradeoffs.

Dr Sardonicus 2022-01-04 02:04

[url=https://apnews.com/article/science-business-galaxies-9f64abcc72b23a403f0df0ec3aa82dd0]NASA's new space telescope 'hunky-dory' after problems fixed[/url][quote]CAPE CANAVERAL, Fla. (AP) - NASA's new space telescope is on the verge of completing the riskiest part of its mission - unfolding and tightening a huge sunshade - after ground controllers fixed a pair of problems, officials said Monday.
<snip>
Flight controllers in Maryland had to reset Webb's solar panel to draw more power. The observatory - considered the successor to the aging Hubble Space Telescope - was never in any danger, with a constant power flow, said Amy Lo, a lead engineer for the telescope's prime contractor, Northrop Grumman.

They also repointed the telescope to limit sunlight on six overheating motors. The motors cooled enough to begin securing the sunshield, a three-day process that can be halted if the problem crops up again, officials said.
<snip>[/quote]

kriesel 2022-01-04 04:10

And[QUOTE]In another bit of good news Monday, officials said they expect Webb to last well beyond the originally anticipated 10 years based on its fuel efficiency.[/QUOTE]

henryzz 2022-01-04 08:54

[QUOTE=kriesel;597074]And[/QUOTE]
They probably suspected this already but couldn't commit.

retina 2022-01-04 09:34

[QUOTE=henryzz;597079]They probably suspected this already but couldn't commit.[/QUOTE]Under-promise and over-deliver.

It sure would be embarrassing if after all these longevity predictions the heat shield rips, or the secondary mirror jams, or a meteorite strikes the transmitter.

tServo 2022-01-04 14:06

[QUOTE=retina;597081]Under-promise and over-deliver..[/QUOTE]


Probably some of that.

However, I did read that it depended on how good that launch was, as precious fuel might have to be used to achieve an acceptable trajectory. A few days after the launch, technicians monitoring the flight path were ecstatic at how well the launch went. Not only was it spot on course but the Ariane delivered superb boost.

Great job, Ariane !

Dr Sardonicus 2022-01-04 16:49

[QUOTE=tServo;597099]<snip>
A few days after the launch, technicians monitoring the flight path were ecstatic at how well the launch went. Not only was it spot on course but the Ariane delivered superb boost.
<snip>[/QUOTE]Back in the day, when live TV coverage of space launches was thorough, Mission Control engineers monitoring a launch would be heard saying things like "Trajectory (or flight trajectory, or flight path) is [i][b]nominal[/b][/i]."

Thus, a new use for an old word was born.

The word "nominal" has long meant (among other things) a figure given in a specification (particularly in manufacturing) like a weight or dimension. The "nominal" is what's in the plan. Of course, actual manufactured items rarely conform precisely to nominal specifications.

When a NASA flight controller described some aspect of a flight as "nominal," it meant that it was actually going according to plan, or at least close enough not to require any correction.

firejuggler 2022-01-04 17:57

[url]https://twitter.com/NASAWebb/status/1478412564983959553[/url]


[code]
[URL="https://twitter.com/NASAWebb"]NASA Webb Telescope

[/URL][URL="https://twitter.com/NASAWebb"]@NASAWebb
[/URL]·
[URL="https://twitter.com/NASAWebb/status/1478412564983959553"]50 min[/URL]
This is it: we’ve just wrapped up one of the most challenging steps of our journey
to [URL="https://twitter.com/hashtag/UnfoldTheUniverse?src=hashtag_click"]#UnfoldTheUniverse[/URL]. With all five layers of sunshield tensioning complete, about
75% of our 344 single-point failures have been retired!
[/code]

pinhodecarlos 2022-01-05 12:39

[QUOTE=tServo;596386]My favorite way to keep track of the status of Webb is one of NASA's pages seen below. It has all kinds of neat stuff on it like distance counters, a timeline of the steps it has done/yet to do, and links to animations of what it is doing or about to do.
Check it out!


[URL]https://webb.nasa.gov/content/webbLaunch/whereIsWebb.html[/URL][/QUOTE]


Thank you, now we are addicted to it. Also this encouraged me to look to where the Voyagers are, stats, etc

firejuggler 2022-01-05 15:09

xkcd

[XKCD]2564[/XKCD]

kriesel 2022-01-05 18:21

[QUOTE=firejuggler;597206]xkcd

[XKCD]2564[/XKCD][/QUOTE]Now just wait ~28 billion years for the portrait to be available here.

chalsall 2022-01-05 19:43

[QUOTE=kriesel;597226]Now just wait ~28 billion years for the portrait to be available here.[/QUOTE]

I actually almost fell out of my chair laughing when I saw firejuggler's link! Thanks; I needed that! I'm going to send it to some friends of mine tonight, after our collective workdays are finished. :smile:

What to me is the most amusing about the idea is I have personally observed many people with really high-end cameras (and built-in super-computers) in their hands trying to take a photo of something they find interesting at night.

But the device is misconfigured and so the flash goes off...

kriesel 2022-01-05 20:00

[QUOTE=chalsall;597236]But the device is misconfigured and so the flash goes off...[/QUOTE]This can produce some interesting effects in the right circumstances. I have a photo from long ago, of a sunrise, taken in a familiar woods, with flash, which makes the photo seem 3-D with nearest twigs and branches highlighted. The hypothetical xkcd "snapshot" would be a record longest time lapse photo. The trick is keeping the camera still; compared to what?

Dr Sardonicus 2022-01-05 22:32

[QUOTE=firejuggler;597206]xkcd

[XKCD]2564[/XKCD][/QUOTE]:lol:

In space, no one can hear you say, "SMILE!"

chalsall 2022-01-05 22:47

[QUOTE=Dr Sardonicus;597248]In space, no one can hear you say, "SMILE!"[/QUOTE]

That is why sign language is so important. All scuba divers (et al) are trained in this.

There are some who cannot hear, and they rely solely on the visual. Reading lips, etc. I am one of those.

The last episode of last year's The Expanse had an excellent example of just how much can be communicated in a narrow bandwidth channel using only photons.

firejuggler 2022-01-08 18:38

Webb is fully deployed!

[URL="https://twitter.com/NASAWebb/status/1479880178021060609?s=20"]https://twitter.com/NASAWebb/status/1479880178021060609[/URL]

Uncwilly 2022-01-08 18:46

The actuators still need to align the mirror segments.

firejuggler 2022-01-08 19:47

another piece of news :
[URL="https://twitter.com/SpaceflightNow/status/1479900879218221060?s=20"]https://twitter.com/SpaceflightNow/status/1479900879218221060[/URL]
[quote= Twitter]
Mike Menzel, JWST’s mission systems engineer at NASA, says 49 of the mission’s original list of 344 single-point failures remain open, and won’t be retired for the rest of the mission. "These 49 are typical of all missions, things like propulsion tanks."
[/quote]

a1call 2022-01-08 21:42

Is winner of the list includes design flaws:

[url]https://www.nasa.gov/content/hubbles-mirror-flaw[/url]

I don’t have a lot of confidence in the Wikipedia-Generation designers.

LaurV 2022-01-09 10:15

[QUOTE=firejuggler;597206]xkcd

[XKCD]2564[/XKCD][/QUOTE]
:davar55: that's a bitter joke, think about what a formidable weapon that mirror is, if retina gets the control of the gyroscopes... :razz:

Dr Sardonicus 2022-01-09 14:02

[QUOTE=a1call;597431]Is winner of the list includes design flaws:

[url]https://www.nasa.gov/content/hubbles-mirror-flaw[/url]

I don’t have a lot of confidence in the Wikipedia-Generation designers.[/QUOTE]With the Hubble mirror, the problem was with the [i]test equipment[/i] that was supposed to insure that the mirror was correctly ground.

Identifying and precisely quantifying the error was vital for enabling the creation of corrective optics. Luckily, the test equipment hadn't been moved or disassembled since it was used.

The [url=http://www.company7.com/c7news/19910003124_1991003124.pdf]Optical Systems Failure Report[/url] described the error:

In the "reflective null corrector" (RNC), the "field lens" was too far from the "lower mirror" by about 1.3 mm.

The report also identified how the error occurred.

With the Webb telescope, the equipment used to test the optics is called ASPA (AOS Source Plate Assembly, AOS = Aft Optics Subsystem). If there turns out to have been a problem with this test equipment, I suppose a failure analysis would be an academic exercise, since there's no way to fix the optics if they're messed up. So I suppose the question of whether the ASPA has been carefully preserved to enable a possible failure analysis is also academic...

kriesel 2022-01-09 14:06

[QUOTE=Dr Sardonicus;597471]With the Webb telescope, the equipment used to test the optics is called ASPA (AOS Source Plate Assembly, AOS = Aft Optics Subsystem). If there turns out to have been a problem with this test equipment, I suppose a failure analysis would be an academic exercise, since there's no way to fix the optics if they're messed up. So I suppose the question of whether the ASPA has been carefully preserved to enable a possible failure analysis is also academic...[/QUOTE]Academic only if NASA neither attempts a robotic repair nor producing another instrument to replace or supersede JWST. It's so much more interesting to learn from past mistakes, by puzzling out the old ones, so one can make new ones, rather than to repeat the old ones.
[QUOTE=a1call;597431]winner of the list includes design flaws:
[URL]https://www.nasa.gov/content/hubbles-mirror-flaw[/URL]
I don’t have a lot of confidence in the Wikipedia-Generation designers.[/QUOTE]Sad part of that story includes that there were warnings that were ignored. Its reflectivity was measured as anomalously good. Its corrective optics was both an engineering feat and a political one. The space allocated to COSTAR required eviction of one of the original onboard instruments. Sacrificed was the [URL="https://en.wikipedia.org/wiki/High_Speed_Photometer"]HSP (high speed photometer)[/URL], which was a mechanically simple less costly yet innovative instrument with less political support from the scientific community.

retina 2022-01-09 14:34

[QUOTE=Dr Sardonicus;597471]With the Hubble mirror, the problem was with the [i]test equipment[/i] that was supposed to insure that the mirror was correctly ground.[/QUOTE]Yes, but it is more than that. Test equipment doesn't align or calibrate itself.

The root problem was with procedures that were not followed to ensure such a basic error never occurred. The procedures had all the potential to catch the error, but some humans assumed too much and never bothered to verify. Perhaps a bit of arrogance was in the mix also with someone saying "I know what I am doing, I'm the expert, just trust me, it'll be fine."

Blaming inanimate objects? Isn't that like the bad workers blaming their tools?

retina 2022-01-09 14:58

[QUOTE=LaurV;597460]... think about what a formidable weapon that mirror is, if retina gets the control of the gyroscopes... :razz:[/QUOTE]Pointing the mirror directly to the Sun would make for a nice temporary light show. A $10B firework. Thanks for the idea. :tu:

chalsall 2022-01-09 15:05

[QUOTE=retina;597479]Pointing the mirror directly to the Sun would make for a nice temporary light show. A $10B firework. Thanks for the idea. :tu:[/QUOTE]

:rofl: Only you... :smile:

Dr Sardonicus 2022-01-09 15:32

[QUOTE=retina;597475]Yes, but it is more than that. Test equipment doesn't align or calibrate itself.

The root problem was with procedures that were not followed to ensure such a basic error never occurred.
<snip>[/QUOTE]I did mention that the report identified how the error happened, and provided a link for anyone interested in the details.[QUOTE=retina;597479]Pointing the mirror directly to the Sun would make for a nice temporary light show. A $10B firework. Thanks for the idea. :tu:[/QUOTE]Alternatively, it might be possible to reorient the thing so the sun [i]shield[/i] "flashes" the Earth. It's fairly reflective, and a [i]lot[/i] bigger than the mirror.

Uncwilly 2022-01-09 16:13

[QUOTE=Dr Sardonicus;597485]Alternatively, it might be possible to reorient the thing so the sun [i]shield[/i] "flashes" the Earth. It's fairly reflective, and a [i]lot[/i] bigger than the mirror.[/QUOTE]It would still be subpixel size for any detector working in the visible and would be too faint for the Mark I eyeball.

Dr Sardonicus 2022-01-09 16:41

[QUOTE=Uncwilly;597488][QUOTE=Dr Sardonicus;597485]Alternatively, it might be possible to reorient the thing so the sun [i]shield[/i] "flashes" the Earth. It's fairly reflective, and a [i]lot[/i] bigger than the mirror.[/QUOTE]It would still be subpixel size for any detector working in the visible and would be too faint for the Mark I eyeball.[/QUOTE]Come to think of it, the sun shield will be reflecting sunlight at us, or nearly at us, all the time anyhow.

Oh, no! This means the James Webb Space Telescope will increase Global Warming!

;-)

kriesel 2022-01-09 18:17

Let's try to run some numbers on that.
When I looked recently at [URL]https://jwst.nasa.gov/content/webbLaunch/whereIsWebb.html[/URL]
JWST was ~686170 miles from earth (~1104300 km).
sunshield length ~21.2 m [URL]https://jwst.nasa.gov/content/observatory/sunshield.html[/URL]
max width 14.16 m, about 2/3 length. Since it is roughly a slender hexagon, not rectangular, the largest diagonal is close to the length.
angle subtended by length = 21.2 / 1104300 / 1000 = 1.92e-8 radians = 0.192 microradians = 192 nanoradians = 0.0396 arc sec. That's well below the ~0.4 arc sec diffraction limit of a 12" optical telescope.
Diffraction limit at 550nm/300mm = 1.83 microradians = 1830 nanoradians. [URL]https://telescope-optics.net/telescope_resolution.htm[/URL]
At a 2m focal length of an amateur's 8" CST, the theoretical image size of the JWST is at most (when oriented sunshade length perpendicular to viewing direction) 384 nanometers at 1x (pinhole camera).

CCD image sensor pixels are typically at 2-6 microns (2000-6000 nanometers) pitch.
Suppose the telescope is used with a 20mm eyepiece for a 100x magnification, and therefore has a field of view of 1/4 degree, 15 arc minutes, 900 arc seconds, ~4500 microradians. [URL]https://telescopicwatch.com/field-of-view-astronomy-calculate/[/URL]
A 4144-wide CCD would be resolving ~1.09 microradians ~1086 nanoradians. JWST might land entirely within one pixel or straddle up to 4 partially, in the best case of sunshield perpendicular to the line of sight. Zooming up to 300x, the diffraction limit of a 300mm/12" aperture scope per CCD pixel won't change that much; a pixel at 300x, 1/12 degree field of view is imaging ~362 nanoradians of sky, still wider than the JWST length. (Unless I've fubared the math along the way in a fatal fashion.)

It gets somewhat more difficult as JWST moves further from earth and nearer L2, ~1,500,000 km away.

Using 30GHz = radar interferometric imaging from multiple locations around the earth (6378 * 2 km diameter)
wavelength = 3e8 m/sec /(3e10 waves/sec) = 0.01 m wavelenth.
Diffraction limit = 0.01 m / 6378000 /2 m ~0.8 nanoradians, much better.
I have no idea how much radar transmitter power it would take to image JWST or what effect on the craft it would have.

Counting the JWST sun shade as 21.2x14.16 x ~0.6 m2 area and assuming 99% reflectivity, 100% capture by earth of a reflected beam, of (93/94)^2 intensity due to JWST's greater distance from the sun, & compared to earth's pi/4 * 6378000^2 m^2 apparent area,
reflected power ratio ~ 21.2 * 14.16 * 0.6 * 0.99 * 1.0 * (93/94)^2 / ( pi/4 * 6378000^2 ) =
174.5 / 31,949,120,782,657.8 = 5.5E-12 of normal solar power directed at earth.

Now if you could focus that roughly 1KW/m^2 of sunshield area remaining after atmospheric filtering (~180KW) into a small spot, well, a small rodent or small bird would disappear in a puff of smoke or at least get singed as they passed through the focal spot due to the earth's rotation and their own motion (a well known issue with focusing solar power generation), or you could melt most metals in it if you prevented the roughly sonic wind from chasing the spot from cooling the crucible too much. It's a rather costly and infinitesimal start on a [URL="https://en.wikipedia.org/wiki/Dyson_sphere"]Dyson Sphere[/URL].

xilman 2022-01-09 19:20

[QUOTE=Uncwilly;597488]It would still be subpixel size for any detector working in the visible and would be too faint for the Mark I eyeball.[/QUOTE]That is an interesting claim. I have no reason to doubt you but I will "trust but verify" regardless.

Given that Gaia, which is much smaller and less reflective than JWST, is visible from L2 with my kit, I look forward to imaging JWST when the observatory is working again. Gaia is ~mag 20-22 which takes 30-180 minutes for a decent SNR; JWST should be 16-18, or 40 times brighter. Ten magnitudes way too faint for naked-eye detection (a factor of 10,000) in general but a specular reflection from the entire sun shield is not "in general".

firejuggler 2022-01-09 20:41

Lego has a JWST st apparently or someone claim.. anyway
[url]https://twitter.com/LEGO_JWST/status/1479887469361479681[/url]

firejuggler 2022-01-24 19:41

JWST arrived home
[url]https://blogs.nasa.gov/webb/2022/01/24/orbital-insertion-burn-a-success-webb-arrives-at-l2/[/url]

Dr Sardonicus 2022-01-24 22:29

[QUOTE=firejuggler;598726]JWST arrived home
[url]https://blogs.nasa.gov/webb/2022/01/24/orbital-insertion-burn-a-success-webb-arrives-at-l2/[/url][/QUOTE]And quite a "Welcome home!" it will be, too. The house[strike]warming[/strike] [i]cooling[/i] party is going to last for [i]several weeks![/i]

tServo 2022-01-25 16:23

[QUOTE=Dr Sardonicus;598740]And quite a "Welcome home!" it will be, too. The house[strike]warming[/strike] [I]cooling[/I] party is going to last for [I]several weeks![/I][/QUOTE]


Cold, indeed. Its final operating temp on the cold side will be about 40 degrees Kelvin !!!
It's around 62 K now.
Since heat is light, the colder it is the less interfering light there is.

kriesel 2022-01-26 01:18

[QUOTE=tServo;598779]Since heat is light[/QUOTE]Radiated heat is photons; convected heat is enthalpy of moving matter; conducted heat is phonons and electrons and maybe more. Space near L2 is not quite a perfect vacuum, even without the discharge of stationkeeping thrusters of JWST. The energy conveyed by solar wind to L2 orbit is probably usually very low density, but not zero.
[url]http://www.dept.aoe.vt.edu/~cdhall/courses/aoe4065/OtherPubs/SPECS/L2environment.pdf[/url]

Dr Sardonicus 2022-02-11 20:18

[url=https://blogs.nasa.gov/webb/2022/02/11/photons-received-webb-sees-its-first-star-18-times/]Star light, star bright, first star I see 18 times tonight...[/url][quote]The James Webb Space Telescope is nearing completion of the first phase of the months-long process of aligning the observatory's primary mirror using the Near Infrared Camera (NIRCam) instrument.

The team's challenge was twofold: confirm that NIRCam was ready to collect light from celestial objects, and then identify starlight from the same star in each of the 18 primary mirror segments. The result is an image mosaic of 18 randomly organized dots of starlight, the product of Webb's unaligned mirror segments all reflecting light from the same star back at Webb's secondary mirror and into NIRCam's detectors.

What looks like a simple image of blurry starlight now becomes the foundation to align and focus the telescope in order for Webb to deliver unprecedented views of the universe this summer. Over the next month or so, the team will gradually adjust the mirror segments until the 18 images become a single star.

"The entire Webb team is ecstatic at how well the first steps of taking images and aligning the telescope are proceeding. We were so happy to see that light makes its way into NIRCam," said Marcia Rieke, principal investigator for the NIRCam instrument and regents professor of astronomy, University of Arizona.
<snip>[/quote]

tServo 2022-03-22 12:52

First images from Webb exceed expectations !


[URL]https://cosmosmagazine.com/space/james-webb-telescope-first-images/[/URL]

jwaltos 2022-03-29 20:00

[QUOTE=tServo;602288]First images from Webb exceed expectations !
[URL]https://cosmosmagazine.com/space/james-webb-telescope-first-images/[/URL][/QUOTE]

[url]https://tenor.com/view/whoa-wow-amazed-shocked-gif-15937479[/url]
(..and Neo's one-liner.)

retina 2022-04-19 11:36

How James Webb's Instruments Work - and What They'll Show Us!
 
[url]https://www.youtube.com/watch?v=MzWfUK0yvdY[/url]
[youtube]MzWfUK0yvdY[/youtube]

Dr Sardonicus 2022-05-13 01:33

1 Attachment(s)
I noticed the following image comparison of the Large Magellanic Cloud in recent news reports. I leave it to interested readers to track down official accounts.


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