website with clear picture

Originally posted by jrod
CASE CLOSED!!!!!

You should know better than to ever use these words around here

Originally posted by browha
Have we not already concluded that this was not possible as it was a clear day?

GM browha!!

Good point my friend!!

From the link above:

"The Shuttle is at peak heat and ionization from reentry.
The Shuttle is banking hard right to decelerate, three minutes before the sensors indicate any problems, the left wing is the hottest and highest charged spot on the shuttle.
The Double Delta design of the wing means that the left wing is creating a larger vortex than the right wing during the bank.
The Shuttle Crosses into daylight (known at higher latitudes to have a current sheet in the ionosphere).
An astronomer in San Francisco captures a luminescent purple corkscrew (similar to a vortex) striking the Shuttle at this time.
Electrophysicists in the U.S. studying high altitude lightning feel there may be a connection but no thunder clouds are prevalent in California at the time to explain it.
The missing piece of the puzzle: A rare Solar Shockwave strikes the atmosphere at the same time the Shuttle is deorbiting.
Excess energy from the solar wind and/or shockwave somehow charges the ionosphere and causes the current sheet to drop to lower latitudes.
The Shuttle being the most highly charged object in the atmosphere, trailing an ion (highly charged) wake becomes a lightning rod.
Even with the Shuttle speed of Mach 18+ lightning within the ionosphere can travel 20 million miles an hour.
The ionosphere becomes a conductor between the shuttles charge and the extra ionosphere charge from the solar wind shockwave.
Heat, ionization and/or the sound (thunder) from the strike begins to affect areas behind the leading edge of the left double delta wing of the Shuttle.
Within 10 minutes the Shuttle breaks up."

Again, *not* "our" points, but from quite a comprehensive study, backing up what was revealed in the TV programme. It might have misguided information (the topic was about Megalightning NOT the Shuttle disaster!!), so I'm "happy" to go with the concensus view that the damaged tiles (caused by the foam hitting the wing on take off) was the reason for the tragedy.

However, the information is imparted as it *was* considered (apparently) as being a possible contributory factor.

Please *don't* shoot the messenger!!

Thanks Genya, some good info there.
Like he said, I'm not saying this *did* happen but it is a possibility.
How can anyone just say 'case closed' if they have never seen the pics?
Explain the corkscrew of purple lightning away...........


Ash

Just as Genya just quoted, the shuttle ionizes the rarified atmosphere around it and produces a plasma. The purple corckscrew is most likely the plasma trail (which would follow the vortices produced by the shuttles lifting body).

Originally posted by Valhall The purple corckscrew is most likely the plasma trail (which would follow the vortices produced by the shuttles lifting body)

Happy with that Valhall!!

As I say, the programme was ostensibly about the "new" lightning, that apparently - and spookily - Columbia was going to reseach whilst in orbit? (There were interviews with the Jewish scientist - can't remember his name - sorry - who has been in receipt of the video footage taken by Columbia, since it was recovered from the crash).

The programme wasn't deliberately "sensational" in any way but "warned" that this type of lightning ie sprite, etc - were 6 times more powerful than "normal" lightning, and that some lightning, rather than being negatively charged was, in fact, positive, causing a tremendous build up in heat/ electrical damage, etc, if it struck aircraft,as it exceeded the current (no pun intend) specification of aircraft design??

As a "closing" 15 minute or so part of the hour long documentary, the suggestion was made about the *possibilty* of lightning (such as described above) having *some* possible effect on the Columbia? It wasn't stated as "fact" nor sensationalised, but discussed the possibility that lightning (as described via plasma/ solar shockwave mechanism) being involved. This was evidenced by the photograph (which seems cannot be sourced!) which showed the purple spiral (which NASA eventually attributed to a camera defect??) and the LF signals received that emulated a "thunder clap" - this via an "official" monitoring station set up to receive such signals to detect nuclear test blasts from - principally - the "old" USSR.

Perhaps the documentary will be shown in the USA at some stage and you'll be able to judge for yourselves (it was an interesting programme!!)

Well, here is an interesting thought that I haven't ever considered before, but seems to me to be very plausible concerning the "thunder clap". It is conceivable that the shuttle could produce a sonic boom as it re-enters the atmosphere. Just as soon as it reached an "atmosphere of substance", I would conjecture there could be a sonic boom.

Originally posted by Valhall
Well, here is an interesting thought that I haven't ever considered before, but seems to me to be very plausible concerning the "thunder clap". It is conceivable that the shuttle could produce a sonic boom as it re-enters the atmosphere. Just as soon as it reached an "atmosphere of substance", I would conjecture there could be a sonic boom.

Actually the shuttle produces a double shock wave as it returns from orbit. My understanding is that they come from the nose and the top of the tail.

Those who have heard one come in always hear the double boom just before visually acquiring the shuttle on its landing approach.

Originally posted by Valhall
Well, here is an interesting thought that I haven't ever considered before, but seems to me to be very plausible concerning the "thunder clap". It is conceivable that the shuttle could produce a sonic boom as it re-enters the atmosphere. Just as soon as it reached an "atmosphere of substance", I would conjecture there could be a sonic boom.

The sounds picked up where compared to previous shuttle re-entries and the profile didn't match (think that included the sonic booms you would expect) but the profile from the thunder clap picked up did seem to fit the profile of a sprite........the details are starting to get a bit fuzzy on me, so maybe someone who watched could tell me if i got that bit pretty much right ?

Originally posted by COOL HAND

Originally posted by Valhall
Well, here is an interesting thought that I haven't ever considered before, but seems to me to be very plausible concerning the "thunder clap". It is conceivable that the shuttle could produce a sonic boom as it re-enters the atmosphere. Just as soon as it reached an "atmosphere of substance", I would conjecture there could be a sonic boom.

Actually the shuttle produces a double shock wave as it returns from orbit. My understanding is that they come from the nose and the top of the tail.

Actually, every sonic boom from an aircraft is a double boom, it just depends on whether the two booms are separated by enough time for the ear to discern the distinction. Most times not. A sonic boom produces an N-wave...called that due to the path traced by the wave. But basically, on a conventional sonic aircraft it's leading edge/trailing edge of the wing.

p.s. Thanks for verifying the re-entry shock. I hadn't ever even thought about this before...but it completely makes sense.

[Edited on 5-28-2004 by Valhall]

Originally posted by Valhall
Actually, every sonic boom from an aircraft is a double boom, it just depends on whether the two booms are separated by enough time for the ear to discern the distinction. Most times not. A sonic boom produces an N-wave...called that due to the path traced by the wave. But basically, on a conventional sonic aircraft it's leading edge/trailing edge of the wing.

What? How can a fighter sized aircraft create a double boom? The boom comes from the front of the aircraft breaking through the sound barrier. The shuttle has a double boom because the top of the tail is higher than the sonic wave that is created by the nose of the aircraft.
In a plane like the Concorde the aircraft is longer and the tail shorter, hence a single boom.

p.s. Thanks for verifying the re-entry shock. I hadn't ever even thought about this before...but it completely makes sense.

They used it in Space Cowboys. I have heard it in person before.

Cool Hand,

Ask and you shall receive:

www.af.mil...

Originally posted by Valhall
Cool Hand,

Ask and you shall receive:

www.af.mil...

You'll have to point out the part about a double boom becuase I did not see it.

I stand by what I originally posted, which was told to me by my aerospace engineering professor.

[Edited on 28/5/04 by COOL HAND]

And I stand by what my aerospace engineering professor told me.

As an aircraft flies at supersonic speeds it is continually generating shock waves, dropping sonic boom along its flight path, similar to someone dropping objects from a moving vehicle. From the perspective of the aircraft, the boom appears to be swept backwards as it travels away from the aircraft. If the plane makes a sharp turn or pulls up, the boom will hit the ground in front of the aircraft.

The sound heard on the ground as a "sonic boom" is the sudden onset and release of pressure after the buildup by the shock wave or "peak overpressure." The change in pressure caused by sonic boom is only a few pounds per square foot -- about the same pressure change we experience on an elevator as it descends two or three floors -- in a much shorter time period. It is the magnitude of this peak overpressure that describes a sonic boom.

There are two types of booms: N-waves and U-waves. The N-wave is generated from steady flight conditions, and its pressure wave is shaped like the letter "N." N-waves have a front shock to a positive peak overpressure which is followed by a linear decrease in the pressure until the rear shock returns to ambient pressure.

As the airforce fact sheet points out, there are lots of factors in whether the rear is heard or not. Attitude, maneuver, etc. Also, I would include the following two:

(assuming steady flight attitude)
1. length of lifting surface - the longer the lifting surface the more likely the second will be heard
2. acceleration of aircraft - if the aircraft is quickly traversing the transonic region I could see the second not being heard, but if it lugs through it, I would think it more likely be detected. - this is a qualitative analysis, just deduction on my part.

The very famous photo of the US air craft breaking the sound barrier which won photography awards clearly shows two booms
we were discussing this the other day in physics actually



Look at the cockpit, there is a 'boom break' there

Or this photo


See?

COOLHAND...do you realize what is developing here? The most dangerous (and yet simultaneously geeky) situation known to a technologically-advanced society...

an aerospace engineering gang war

(My professor can beat up your professor ).

We hereby formally declare ourselves the crips of this situation...you guys will have to take bloods.

Let the dissertations begin!

LOL

[Edited on 5-28-2004 by Valhall]

Originally posted by Valhall
Let the dissertations begin!

Funny, can I assume that either one of you is a aerospace engineer?

The shockwaves develop and progress along the airframe, of that there is not doubt. However, there are also smaller ones that form along as it approaches the speed of sound. If you look at the pictures that browha provided you can see that they develop in LP areas along the airframe. For example, in the F?a-18 one, you can see that the front wave has formed behind the highest point on the canopy in a LP area.
Once it passes through that barrier it is a single compression wave that is generated that breaks through the sound barrier.

Browha your pics show aircraft approaching the speed of sound, not breaking through them. After you break the speed of sound the visible waves (only in high humidity) disappear. I have seen them happen with my own eyes.

[Edited on 28/5/04 by COOL HAND]

You can assume I am...and my professor. I was not referring to browha.

Originally posted by COOL HAND
You'll have to point out the part about a double boom becuase I did not see it.
[Edited on 28/5/04 by COOL HAND]

Actually, I've *heard* it, as have millions of people.

I was at Cape Canaveral the day one of the shuttles landed and yes, we did distinctly hear the double boom.

Originally posted by Valhall
COOLHAND...do you realize what is developing here? The most dangerous (and yet simultaneously geeky) situation known to a technologically-advanced society...

an aerospace engineering gang war

(My professor can beat up your professor

).

We hereby formally declare ourselves the crips of this situation...you guys will have to take bloods. Let the dissertations begin!
[Edited on 5-28-2004 by Valhall]

ROFL!!!!

And may I remind y'all just WHOSE turf you're on?? My professors can... uh... ooops!

(g) On a more serious note, as moderator I'd like to applaud all who are taking part in the thread for the good research and excellent discussions. I think this is the kind of research and interaction that makes this a superior board!

oh... and don't forget to hit the 'vote for ATS' button that votes for us on Topsites.com. I took a look at the other sites in the top categories (she says, quietly rolling her eyes...) Yeah, we got 'em beat. It's about time they knew it, too!

Very good paper on sonic boom wave systems and the leading and trailing edge shock waves:

automation.ce.rpi.edu...