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Hubble Servicing Mission #4
Guest_PhilCo126_*
post Jul 13 2008, 12:29 PM
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Saving Hubble ... some enthusiast believe NASA migh fund a mission to bring HST down to Earth for display in NASM Washington D.C.
Can You believe that ? laugh.gif
http://www.pbs.org/wgbh/nova/sciencenow/0303/01.html
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dvandorn
post Jul 13 2008, 04:44 PM
Post #17


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The original plan was to bring Hubble back, actually. It went away after the Columbia accident, mostly because mooring the Hubble properly (and prepping it for return) requires EVAs, and all of the Shuttles except for Columbia had their built-in airlocks removed. For ISS operations, the airlock is part of the docking adapter, which extends into the payload bay.

The add-on airlock makes the remaining space in the payload bay shorter than Hubble -- so none of the Shuttles currently flying can fit both an airlock *and* the Hubble in their payload bays.

Without Columbia, you'd have to do an expensive re-fit of one of the existing orbiters to add back the internal airlock in order to bring Hubble back. And that's just not cost-effective by any stretch of the imagination.

-the other Doug


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jmjawors
post Jul 13 2008, 07:29 PM
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I *believe* the docking adapter is being removed from Atlantis for this mission, though. The point still stands, it's not cost-effective to repeatedly do this, and shuttle missions are now an endangered species anyway.

It's too bad we can't bring Hubble back one day.


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hendric
post Jul 14 2008, 06:13 AM
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How about just the mirror? I know, I know, there's no way an EVA could remove the mirror from the telescope. What about a bottom first re-entry that uses the electronics etc. to "heat shield" the mirror? There's got to be several thousand pounds of "stuff" (http://www.base24.com/hubble.htm) between the mirror and the bottom, along with enough structural integrity to survive a launch. Plus, the design should cause it to "weathervane" with the heavy side forwards anyways.

So maybe it's not a question of can it survive, but would anyone go through the trouble of looking for it and recovering it. The Kansas Cosmosphere did, after all, recover Liberty Bell 7, and the Hubble is much fresher in the public's mind.


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jmjawors
post Jul 14 2008, 06:33 AM
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I doubt any part of Hubble will survive re-entry. Maybe some small charred bits here and there, but Hubble's re-entry will be targeted over ocean, so those tiny bits will surely be lost to the sea. There's a vast difference between a Mercury capsule and Hubble.

Thinking about all this did remind me of the biggest constraint towards any shuttle mission to Hubble. In fact, it's the one thing that has made this current mission so difficult; the lack of "safe haven" on the ISS if there was any significant damage to the shuttle during launch. STS-125 is essentially a two-shuttle mission. Atlantis will launch to Hubble, and meanwhile Endeavour will be poised on the other pad just in case a rescue mission is needed. So any Hubble mission needs two tanks, four boosters and two fully processed shuttles to pull it off.

Though it's sad not to have the telescope itself on the ground, the photographic and scientific catalogue Hubble has compiled will last for many many generations. So even without the telescope physically present, its legacy will long be remembered.

(We still have many more years of observations to make with Hubble, so let's not get ahead of ourselves. wink.gif )


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djellison
post Jul 14 2008, 07:22 AM
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The mirror will survive, but that's about it.

Doug
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hendric
post Jul 14 2008, 07:34 AM
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QUOTE (jmjawors @ Jul 14 2008, 12:33 AM) *
There's a vast difference between a Mercury capsule and Hubble.


Of course! I don't expect a shiny, pristine 2.4m mirror to be scooped off the bottom of the ocean by Alvin, but I'm optimistic considering the large chunks of skylab (that was forced into a tumbling reentry) found after its demise. Considering Hubble weighs 24,500 lbs, most of which is behind the mirror (1,800 lbs itself), chances have got to be high that significant pieces survive.

Piece of the mirror, or just part of a fuel tank, if somebody does recover part of Hubble, I would pay to see it.

Just on a lark, I tried calculating a rough estimate of the mirror's density:

2.4m^2*3.14159-.6m^2*3.14159 = 16.9m^2 area
The thickness I get from http://www.scienceclarified.com/scitech/Te...pes/Hubble.html as 12" or .305m

So a volume of 5.15m^3 for the mirror. Plugging in the weight of 828kg gives a density of 160kg/m^3, or about 15% of (pure) water's density!

A 100% intact mirror could bouy 5,000+kg on its own. blink.gif

That, or my math is totally broken. laugh.gif Can anyone spot the mistake?

I'm assuming the mirror's honeycomb cells are sealed based on the above reference that states 1.5" of solid glass plate were sealed to the front and back, and abraded to 1".


--------------------
Space Enthusiast Richard Hendricks
--
"The engineers, as usual, made a tremendous fuss. Again as usual, they did the job in half the time they had dismissed as being absolutely impossible." --Rescue Party, Arthur C Clarke
Mother Nature is the final inspector of all quality.
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jmjawors
post Jul 14 2008, 02:55 PM
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Wow, I'm surprised to learn that. That's pretty cool.


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Guest_PhilCo126_*
post Aug 6 2008, 03:52 PM
Post #24





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Can't wait to see the mission getting started:
http://www.nasa.gov/mission_pages/shuttle/...4/overview.html
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Guest_PhilCo126_*
post Aug 7 2008, 08:04 PM
Post #25





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Here’s a superb artist’ impression of the HST:
http://www.spacetelescope.org/goodies/post...l/hubble01.html

And for the Servicing mission:

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Guest_PhilCo126_*
post Aug 23 2008, 10:07 AM
Post #26





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Just read some interesting statistics on micro-meteroid impacts on the Hubble Space Telescope (HST):
In February 1997, a total of 788 impact scars to the detectable limits of 0.5 centimeters were found on HST's external surface. Compared to the December 1993 servicing mission, an apparent increase of 20 impacts per square meter was noted!
ohmy.gif
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