James Webb Space Telescope updates

[ckikilwai]

article: http://www.space.com/businesstechnology/070523_techwed_jwst_dock.html<br /><br />They say they will add a dockingring to the JW telescope, just in case something wouldn't deploy well.<br />It can't be used to replace instruments or change out things.<br /><br />The question I ask myself is if the Orion isn't too expensive to just deploy something that is jammed.<br />Why don't they add some kind of robot to the telescope to do that?<br />Or if the weight would be a problem, design a robot you can launch to it on a small rocket.<br />

 

[MeteorWayne]

Well if there's a docking ring there, something else can also be designed to match it.<br /><br />However, time is important, since the JWST will depend on cryogenic fluids to perform, IIRC. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[jimfromnsf]

JWST doen't use cryogenic fluids. It uses its orbit and sunshield to get the low temps required. <br /><br />Like the article said, this is for "Oh sh*ts" and not for servicing.<br /><br />As for a robot, they aren't advanced enough

 

[MeteorWayne]

Thanx, I must have had it confused with another craft. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[heyscottie]

My question is whether Orion has the capability to get out there. (Obviously, the answer must be "yes", or there would be no inclusion of a docking port.) Getting to the Lagrange point should not be too difficult, no more difficult than getting to the moon. But how do we STOP there?<br /><br />I guess now that I think about it, this problem has obviously been solved, since we have machines at Lagrange points already. How did they get there? Obviously, you can't just rocket out there as fast as you can, unless you are carrying enough fuel to stop yourself there. Is it some long process of orbital nudges until you finally get there? And if so, would that be feasible for a manned mission?

 

[ckikilwai]

I'm not so familiar with the "Langrange Point", how far is it from Earth?<br /><br />And wasn't the Orion going to be ready in 2015? So the JWST has to wait at least 2 year before Orion can get there...<br />Again, if they know what the problem is, why not design a small robot to do the job, and launch one to it.

 

[MeteorWayne]

JWST description of L2 Lagrange point link <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[jimfromnsf]

"1) Are we to conclude that the reflector mirror and sunshade are fully deployed in a parking orbit, or is the Orion in 2013 going to have the capability of reaching the Lagrange Point where JWST is going to set up shop?<br /><br />2) Are the JWST and Orion now joined at the hip? In other words, does a delay in the Orion project delay JWST?"<br /><br />1. No, Ariane will put it in the operational orbit.<br /><br />2. no<br /><br />It will have to be an Orion on Ares IV or V launch; or an Orion on Ares I with an Ares IV or V launch<br /><br />This is one of those low risk changes to cover "Oh sh*ts" and not for servicing. <br />The adapter is passive and doesn't weigh so why not add it. HST is getting one too.<br /><br />It is the same thing as Solar Max. It was launched before STS- 1 and it had a shuttle grapple fixture

 

[kdavis007]

It would cost more to develop a robot to service the JW Telescope....

 

[holmec]

I wonder if in the case of service mission if they would outfit the Orion with a canadarm, <br /><br />Actually I suppose any large payloads going to the telescope would require the use of Ares I and V for Orion capsule, payload part for the telescope and a booster rocket of some size. <div class="Discussion_UserSignature"> <p> </p><p><font color="#0000ff"><em>"SCE to AUX" - John Aaron, curiosity pays off</em></font></p> </div>

 

[ckikilwai]

wow L2 is more then 4 times the distance earth moon!<br />Will one Ares V do to fly such distance?<br /><br />If it would be done, it would be one of NASA's more spectacular missions, a space walk with a view of the whole earth and the moon <img src="/images/icons/tongue.gif" />

 

[holmec]

<blockquote><font class="small">In reply to:</font><hr /><p>wow L2 is more then 4 times the distance earth moon!<br />Will one Ares V do to fly such distance? <p><hr /></p></p></blockquote><br /><br />I guess it depends on the size and performance of the TL2I (Trans L2 Injection [derived from TLI]) booster. <br /><br />BTW here is a nice link on Langrange Points<br />http://www.physics.montana.edu/faculty/cornish/lagrange.html <div class="Discussion_UserSignature"> <p> </p><p><font color="#0000ff"><em>"SCE to AUX" - John Aaron, curiosity pays off</em></font></p> </div>

 

[jimfromnsf]

No arm on Orion. Orion is not the shuttle. Shuttle way of doing things is not the norm anymore. Skylab didn't have an arm

 

[holmec]

<blockquote><font class="small">In reply to:</font><hr /><p>No arm on Orion. Orion is not the shuttle. Shuttle way of doing things is not the norm anymore. Skylab didn't have an arm<p><hr /></p></p></blockquote><br /><br />But ISS does. And the COTS demo flight are supposed to be captured using the Canadarm II. I don't think the arm as a subsytem will go away I think its much too valuable.<br /><br />Orbital Express's Astro has an arm:<br />http://www.darpa.mil/tto/programs/oe.htm<br /><br />I just pondering the possibilities of this for the future. Since Canadarm II can 'inch worm' around the space station even before the trolley, it wouldn't far fetched to develop a wirelesly controlled arm that could attach to Orion capsule or service module or a module for parts serviceing. Essentially I looking at the arm as its own system. <div class="Discussion_UserSignature"> <p> </p><p><font color="#0000ff"><em>"SCE to AUX" - John Aaron, curiosity pays off</em></font></p> </div>

 

[jimfromnsf]

For orbital bases or servicing vehicles it is good, but not for a crew delivery vehicle, which CEV is<br /><br />The SSRMS gets power and commanding from where it attaches. Wireless would necessitate independent power source

 

[christine16]

very long way fro orion <br /><br />how long it should travel to it?

 

[exoscientist]

<i>JWST doen't use cryogenic fluids. It uses its orbit and sunshield to get the low temps required...</i><br /><br /> Actually it also uses liquid helium to keep its instruments at the very low temperatures required for the very sensitive infrared measurements.<br /><br /><br /> Bob Clark <div class="Discussion_UserSignature"> </div>

 

[holmec]

It all depends on how fast you go to get there and how fast you can stop. So its going to be a matter of fuel management.<br /><br />It takes 2 days to get to ISS, Appollo took 3 days to get to the moon. And that's a huge difference in distance. <br /><br />It will be very interesting to see how they navigate to L2. <div class="Discussion_UserSignature"> <p> </p><p><font color="#0000ff"><em>"SCE to AUX" - John Aaron, curiosity pays off</em></font></p> </div>

 

[CalliArcale]

<blockquote><font class="small">In reply to:</font><hr /><p>For orbital bases or servicing vehicles it is good, but not for a crew delivery vehicle, which CEV is <p><hr /></p></p></blockquote><br /><br />Much as I like the RMS and SSRMS, I have to agree. I mean, where would they put the thing? Orion is a capsule-type spacecraft; it doesn't have the real estate the Shuttle has. And an arm would be a much larger fraction of its liftoff mass than it is for Shuttle.<br /><br />I could forsee serious servicing being done down the road with JWST; you never know what somebody might come up with, and then justify to the high mucky-mucks. But not in the forseeable future. Frankly, I think "reusability" and "serviceability", while noble concepts, in practise ended up being little more than buzzwords to give a mission more appeal when selling it to the budget people. While I love what's been done with the Hubble servicing missions, I do wonder what the cost difference would've been to just launch more space telescopes. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[nacnud]

IIRC JWST has a life of only 8 years due to propellant depetion, being able to refuel it is about the only thing that jumps out as being worth it. Assuming that it is still working by 2020 that is.

 

[jimfromnsf]

JWST does not carry any liquid helium

 

[docm]

<font color="yellow">JWST does not carry any liquid helium</font><br /><br />Uhhh....not so Jim. <br /><br />The sunshield provides passive cooling to 40K for much of the telescope, but there is also a four-stage pulse tube cryocooler and electronic controller to provide cooling for the MIRI IR detectors.<br /><br />Like any cryocooler it has a compressor & a coolant reserve <i>plus</i> the cryocooler head on the detectors is ~20 meters from the cryocooler proper, meaning there are at least 40 meters of coolant lines. Probably closer to 50 meters.<br /><br />More failure modes than you can count in a mission-critical system, especially when you count those <b><i>long</i></b> coolant lines.<br /><br />NASA announcement link....<br /> <br /><blockquote><font class="small">In reply to:</font><hr /><p><b>Contractor Selected to Chill Instrument for JWST Mission</b> 04.06.06<br /><br /><font color="yellow"><b>NASA recently selected Northrop Grumman Space Technologies of Redondo Beach, Calif. to develop a super-frigid mechanical helium cryocooler for the Mid-Infrared Instrument (MIRI) on the James Webb Space Telescope.</b></font><br /><br />The award concludes a five-year development program which yielded ground-breaking advances in cryocooler technology. “This selection marks a major milestone for the mission,†said James Webb project manager Phil Sabelhaus. “We now have all of our major industrial partners under contract.â€<br /><br />A large sunshield will super cool the observatory to just 40 Kelvin, which is minus 388 degrees Fahrenheit. However, the MIRI detectors will need to operate at even colder temperatures. That’s where the cryocooler takes over, absorbing heat from the instrument, enabling the detector temperature to drop to a mere six degrees above absolute zero. Operating at this chilly temperature will allow the MIRI to detect room temper</p></blockquote> <div class="Discussion_UserSignature"> </div>

 

[jimfromnsf]

I am referring to a large cryostat full of it , that is a consumable

 

[MeteorWayne]

Well you said <br />"jimfromnsf<br />asteroid<br />05/25/07 09:08 PM<br /> Re: James Webb telescope will have dockingring for Orion [re: exoscientist][link to this post] Reply <br /> <br /> <br /><br /><br />JWST does not carry any liquid helium <br />"<br /> <br /> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[docm]

Checking the diagrams of pulse type cryocoolers on NASA's site and others <i><b>all</b></i> show a reservoir tank in-line with the pulse tube. Examples below.... <br /><br />Plus; how much coolant do you think is in that 40+ meters of line between the cryocooler and the cooling head on the MIRI? <div class="Discussion_UserSignature"> </div>