Thanks, Donnie. Yes, that was my question: the Space Shuttle being struck by space debris, not the public on ground.

Sorry, I didn't make that clear earlier.

Over California? That would be before the reentry, correct?

Geographically, at what point (over which geographic location) does the shuttle would be entering the thinnest layers of out atmosphere?

It would have been relatively early in the reentry.

In fact, the shuttles normally fly within the upper reaches of the atmosphere while on orbit. On the nightside, a faint glow is often seen around the tail and OMS pods, due to collisions with oxygen atoms.

Naturally, as the orbiter descends, it encounters increasing atmospheric density. It would certainly be experiencing significant heating over California on the way to a Florida landing. The peak heating would have been over Texas, just where the main breakup occurred.

Answer to #1 – yes-it is a plasma vapor trail caused by the superheated atmosphere. IRRC it’s the same thing you see behind a meteor. (Its been a while since I’ve read BA’s book)

Can’t really help you with question 2 – I just thought that when Columbia broke up there was a bloom in the plasma trail. Don’t know if the forces involved would have caused an explosion.

[fixed some formatting]


<font size=-1>[ This Message was edited by: SpacedOut on 2003-02-04 21:45 ]</font>

Thanks for the response. Now, a couple of questions:

>>...around the tail and OMS pods, due
1. What is OMS? (pardon my ignorance)

>>...collisions with oxygen atoms.
2. How would these Oxygen atoms "stay" there? I main, why don't they "fly" away into the depths of space - vacuum?

Orbital Maneuvering System. Small(er) rockets at the back of the shuttle, above the main engines. Used to adjust the orbit as needed.

__________________
Everything I need to know I learned through Googling.

http://elf.gi.alaska.edu/
This site says that sprites are visible to at least 95 kilometers height. That's about 300,000 ft. They may extend higher but there may not be enough air for them be visible above that.

1) Orbital Maneuvering System. (ToSeek is exactly right.) Those are the smaller rocket motors that sit "above" the main engines; the two big bulges at the tail are there to house the OMS engines. You often see those bulges in pictures of the cargo bay taken from inside the crew compartment.

2) The same reason the rest of the atmosphere stays put: gravity. To escape completely, a particle has to reach escape velocity (something around 25000 mi/hr). Some O2 atoms may occasionally do so at those altitudes through collisions with particles of the solar wind or cosmic rays, but most don't. So there they stay.

The atmosphere doesn't have a "top"... it just gets thinner and thinner the farther out you go. In practical terms, it's a near-perfect vacuum at the altitude where the shuttle operates, but go twice as high and it's an even better vacuum. And at some point, it becomes as tenuous as the solar wind, and then I suppose you can say you're out of the Earth's atmosphere and into the Sun's.

Of course! [img]/phpBB/images/smiles/icon_biggrin.gif[/img] I always wondered what those "bulges" were, even though I was aware of the rocket nozzles sticking out of those areas, it never occurred that these "bulges" house the engines.

OK, now I know what OMS stands for. Thanks.

Excellent! Thanks for the education. I guess that's the reason why atmosphere didn't stay on Mars - it doesn't have enough mass to have the gravity that is enough to keep the "air" (I mean atmosphere) on its surface.

What would you say the level of vacuum is at the height the Shuttle operates - how many times is this better then the best vacuum we can produce on Earth?

Thanks.

Oh, you would have to go and get technical on me... [img]/phpBB/images/smiles/icon_smile.gif[/img]

I don't have numbers for you, but if memory serves, the vacuum at typical shuttle altitudes is better than a laboratory vacuum, but not astoundingly so. We can make a pretty good vacuum on a small scale, but not in "large quantity" [img]/phpBB/images/smiles/icon_smile.gif[/img]

Still, at 100 miles up, it's practically a pressure cooker compared to the really hard vacuum out between the galaxies - one atom per cubic meter or so out there, on average.

Oh, you would have to go and get technical on me... [img]/phpBB/images/smiles/icon_smile.gif[/img]
Hey, you are the Bad Master. I am just a Bad Apprentice [img]/phpBB/images/smiles/icon_biggrin.gif[/img]

We can make a pretty good vacuum on a small scale, but not in "large quantity"
I like the way you put it. We "make" good vacuum. What do you make again - oh it is nothing. We make pretty good nothing. [img]/phpBB/images/smiles/icon_smile.gif[/img]

one atom per cubic meter or so out there, on average.
Yup, that's what I was looking for.

Thanks a bunch.

This is from the SF Chronicle February 2

Early in the article:

... taken with a Nikon-880 digital camera on a tripod, reveal what..

The Nikon 880 is indeed a digital camera.
Now, toward the end of the article...

"... but it showed up clear and bright on the film when I developed it," the photographer said.

It struck me as very odd that a photographer, especially an amateur astronomer who would be very familiar with his own camera, would make this mistake.

__________________
Popeye ate spinach because they wanted to market spinach to children. What a relief, then, that Superman doesn't eat Kryptonite.

I'm betting that he used 'developed' for the lack of a better term. Or he had a brain lock on 'download' and went with 'developed' as it is close in a general sense, i.e. got the pics out of the camera.

Kizarvexis

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"We don't just borrow words; on occasion, English has pursued other languages down alleyways to beat them unconscious and rifle their pockets for new vocabulary." - James D. Nicoll

I might have been a little too reactive there, since I do say "filmmaking" while I'm editing digital video. Some terminology is pretty stubborn. You have a good point there.

I certainly did not mean to discount his claim; how could I? I haven't even seen the image, and I have no reason to doubt him.

I am eager to see what it is that caused that light.

__________________
Popeye ate spinach because they wanted to market spinach to children. What a relief, then, that Superman doesn't eat Kryptonite.

Here's an update.
http://www.sfgate.com/cgi-bin/articl...06/MN22145.DTL
They still haven't connected to the storms to the west of Hawaii. The plasma trail went right over these. The plasma trail persists and makes a good path to the orbiter even over that distance. Ignorasphere.

Wow! I thought you were just making up the term "Ignorasphere" until I followed the link. Pretty deep stuff. John, you may be right about lightning all along [img]/phpBB/images/smiles/icon_confused.gif[/img]

There are explosive charges in the wheel well in case the door gets stuck. The temperatures recorded were not sufficient to set them off, according to the program manager. But could a lightning strike have done it?

I dunno Mr. Kierein...

Apollo 13 got hit directly by lightning at least twice in stage 1 ascent and had all kinds of explosive charges on board...

On the other hand, Gus Grissom always said (I think), "It just blew..."

Might be interesting to compare the track of MR-4 to Columbia. Hmm.

Doug.

(Corrected sp...)

<font size=-1>[ This Message was edited by: DALeffler on 2003-02-06 20:34 ]</font>

Apollo 12, actually, though that doesn't affect your point.

__________________
Everything I need to know I learned through Googling.

Actually, I mentioned the Apollo 12 lightning strike a bit back [img]/phpBB/images/smiles/icon_smile.gif[/img]

Actually, unknown at the time, a rocket can spawn lightning strikes. The University of Florida studies lightning by lauching small rockets in an attempt to stimulate strikes in predictable places. After all, you can't study them if you don't know where they will be.

I don't think Columbia would have stimulate a lightning strike. After all, the external skin of Columbia is cermic tile, not a metal conductor like a Saturn V or the small rockets used in research.

The U of Florida Lightning Laboratory page is at http://www.lightning.ece.ufl.edu/

Rob