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Question for 25F
-------------------- Don't some of the numbers in your very infomative post need some medical attention? e.g. "orbiter slows to below Mach 1 at about 49,000', 22 NM (25 SM, 40 km)" "place 4,400 NM (5063 statute miles/3160 km) from the landing site" Cheers, http://home.infi.net/~blueblue/_uimages/pi.gif |
Picky, just to make it clear to all, everything after "excessively long post" is taken from the sci.space.shuttle newsgroup. The info was put together in something of a hurry, while trying to fend off hundreds of newbies asking why the Shuttle didn't just go back to the ISS...
Your first quote is altitude in feet followed by distance from landing. The second one does need fixing. Aardvark, I'm afraid I don't quite get your point. I think we can take it that acceleration here is measured with respect to the inertial frame of reference of the shuttle itself. It starts at zero, in orbit, and increases during re-entry. My reading of the text is that it is held to about one G. Typical maximum G is 1.6. (For Soyuz craft it is 4-5G, if not more). |
In his post, steamchicken suggested that Russian design philosophy might be worth looking at. I have to agree. They try to keep things simple. In the days of the cold war, when the space race was in full swing, the Americans spent millions designing a pen that would work in zero G (the "space pens" that can now be bought for five quid from mail order catalogues).
The Russians had a far better idea. They used pencils. |
Just did a search for previous report of damage which might be relevant and found two.
STS-27 Mission report: Initial post-flight inspections of the exterior surface of the Orbiter revealed significant tile damage with 298 damage sites greater than 1 inch in area, and a total of 707 damage sites on the lower surface of the vehicle. The area of major damage was concentrated outboard of a line from the bi-pod attachment to the external tank (ET) liquid oxygen umbilical. One tile was missing on the right side slightly forward of the L-band antenna. Also, there were many damage sites consisting of long narrow streaks with deep gouges. NASA Reference Publication 1390: (STS-45) The Atlantis suffered 2 gouges on the upper portion of the right wing leading edge. The most probable was a low-velocity (relative to the spacecraft) debris impact on orbit or during re-entry. However, Johnson Space Centre engineering has not ruled out prelaunch or ascent debris as the cause of the damage. This particular event raised concern about the consequences of a higher energy impact to the integrity of the spacecraft. |
I think Nasa knew, or had the ability to know, by using satellites used for spy missions, the extent of the damage, and the consequences for a return to earth. No one at NASA had the balls to speak up.
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After all (as someone suggested) if there was a problem with tiles (if that ends ut being the cause) there could have during a space walk been the chance to effect a "CAT Q I landing" repair. Only possible solution would have been a rushed rescue mission. |
CAT1, the space pen story is a nice story, but it is just that:
http://www.snopes.com/business/genius/spacepen.htm For early flights both "teams" used pencils. The Fisher pen company developed the space pen at their own expense. It has been used on all manned space flights since Apollo 7, according to all the references I can find. Bubbette, could you provide references for your claims, please? Debris in New York, unless that's the New York, Texas, Cheesecake Co., seems somewhat unlikely. Similarly I have yet to see a credible rescue scenario anywhere. Lastly have you a reference for the CIA stating that they could have inspected the shuttle from their satellites? |
It seems that the NASA line is that even if they had been aware of the problem there was nothing to be done. One question I have is that whether reducing the weight of the shuttle could have improved the odds.
Could a reduced weight have helped by:- - Changing the heat 'map' on the tiles due to an altered angle of attack? - Reducing the maximum temperatures to be encountered? - Increase manouverabilty (vary pitch to vary heating, counter/mitigate left yaw/roll ) of the vehicle? - Less stress as on ailerons/elevators etc? - Reducing the speed at which (no gear?) that the astronauts would have had to bail out? Maybe the answer is that thay had no means to do this. Could they have:- - Dumped the module in the cargo bay? - Dumped at much as possible through an (fitted?) airlock? - Dumped air, used (below safe min) fuel |
CAT 1: Pencils are not the best thing to have in a closed electronics-filled space with little or no gravity because graphite dust conducts electricity. Tiny particles of conductive floating residue would have some potential ability to bolix onboard sensors and electronics.
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25F I heard the debris in New York late last night on the local radio--maybe I misheard or they misspoke because it's not on the website (www.1010wins.com). Re the spy satellite, my friend told me that; I will check with him for a source. And now, on the late night radio conspiracy show (http://www.coasttocoastam.com), they're saying it was terrorism; or sabotage. He's citing the report after the Challenger stating that the tile-layers were not using the glue correctly. . . (hey--I'm just reporting what they're saying--this I don't know if I believe).
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High altitude lightning? I don't know if such a thing is possible, but this story I just ran across raises some interesting questions.
http://www.sfgate.com/cgi-bin/articl.../05/CAMERA.TMP "Top investigators of the Columbia space shuttle disaster are analyzing a startling photograph -- snapped by an amateur astronomer from a San Francisco hillside -- that appears to show a purplish electrical bolt striking the craft as it streaked across the California sky. " |
The problem with Bubbete's view that they could have conserved supplies and been rescued is that you run the high risk of loosing another shuttle and another crew.
If this problem with the tiles was an inherent design flaw then I would salute the commander willing to take another shuttle up within a 2 week prep period; but he would be making a very large risk indeed. Technically, there would be a 1 in 107 chance of endng up in the same position as Columbia, although with twice the crew dead and an abandoned shuttle doomed to burn up in the atmosphere. |
Just seen this on ceefax:
NASA REJECTS U.S. SHUTTLE DAMAGE THEORY A piece of insulating foam is no longer thought to have caused the break-up of the Columbia space shuttle, Nasa says The probe had focused on damage to tiles under the left wing, which it was thought could have caused by a chunk of foam insulation on take-off. But Nasa said the foam debris was neither heavy enough nor traveling fast enough to cause the damage. The probe will now focus on the automatic control system. BBC News / In depth, shuttle disaster |
ionspheric plasma jet?
Electrodynamics is far from my field, but I was struck by the great interest NASA took in a series of photographs taken in San Francisco as Columbia was flying overhead, and which MAY show a purple streak striking the spacecraft.
Excerpts from the story in today's San Francisco Chronicle: Of particular interest is a startling image taken by an amateur astronomer in San Francisco, which appears to show a purplish bolt of lightning striking Columbia at it streaked across the predawn skies. NASA dispatched former astronaut Tammy Jernigan, who has flown five times on the shuttle, to pick up the photos and the camera itself. She delivered them to a NASA jet at Moffett Field, where they were to be flown to Texas on Wednesday. Jernigan said she did not know what to make of the image but agreed it needed to be analyzed. "We sure will be very interested in taking a very hard look at this," she said while examining the picture in the photographer's San Francisco home. The images could turn out to be the result of a subtle jiggle of the camera or might depict some rare electrical phenomenon in the zone known as the ionosphere, more than 40 miles above Earth. Photo analysts should be able to match the location of the strange lightning-like image with a precise point in space and time during the orbiter's descent. That's because the photograph also depicts a crisp field of stars in the background, which provide astronomical reference points. The amateur astronomer, who does not want his name released, said he believes he snapped the images at 5:53 a.m. Saturday. http://bex.nsstc.uah.edu/RbS/UGRANT/ugrant.html A paragraph from the paper says thus in discussing ionospheric jets: Note that charge separation occurs as soon as the dipole gradients are seen by the sunward convecting neutral plasma. It is generally assumed that the high conductivity of the cold plasma (assumed to be zero temperature, and therefore oblivious to magnetic gradients) allows the electrons to be redistributed in a way to maintain quasi-neutrality. Recent observations show that this assumption of sufficient cold plasma fails during a magnetic storm, and real charge separation may occur. Under these conditions, cold plasma from distant regions is required, and indeed accelerated to shield the space charge. POLAR made recent measurements of a 30 keV field-aligned potential drop during a small storm, that populated the ring current with accelerated ionospheric plasma (Sheldon98a). Thus the ring current can be explosively driven on timescales of minutes by upward ionospheric jets, as is evident in high time resolution magnetograms. I also came across a reference in a paper on space weather to temporal changes in ion density depending on the season and time of day. At northern mid-latitudes, the ion density is most negative in mid-winter and just before dawn. Columbia transited the San Francisco Bay area in the hour before dawn (PST). http://www.agu.org/sci_soc/eosbuon.html I did come across several papers by Russian scientists on kinetic forces associated with plasma jets, but didn't grasp a good sense of how weak or powerful such jets might be. |
Here is an interesting view from the Nexrad Loop
All these discussions bring up a question. I understand that a speed limit is likely to be caused by the rising temperature during re-entry, but apart from that does the shuttle have a Mmo? 7 7 7 7 |
National Public news just reported that, according to AW & ST, the USAF has given NASA photographs of the shuttle. The photographs reveal major structural damage at the root of the left wing/fuselage join.
---------------------------------------------------------- KENNEDY SPACE CENTER, Florida (CNN) -- Photographs taken by an Air Force tracking camera shortly before the space shuttle Columbia disintegrated show serious structural damage to the shuttle's left wing, an aviation magazine reported Friday. The images, captured about a minute before the shuttle broke apart, show a jagged edge on the left wing structure near where the wing begins to intersect with the fuselage, according to a report in Aviation Week & Space Technology. Columbia's right wing and fuselage appear normal in the photos, the magazine said. The damage to the left wing indicates either a small structural breach, such as a crack, or that a small piece of the wing's leading edge fell off, according to the magazine. It said NASA investigators at Johnson Space Center in Houston, Texas, are analyzing the pictures..................... |
USAF Imagery Confirms Columbia Wing Damaged
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From the STS-107 SECOND DAILY REPORT on the NASA site (I think that’s where I got it from):
-------- Start quote --------- STS-107 SECOND DAILY REPORT …….. At approximately 81 seconds mission elapsed time (MET), a large light-colored piece of debris was seen to originate from an area near the ET/Orbiter forward attach bipod. The debris appeared to move outboard and then fall aft along the left side of the Orbiter fuselage, striking the leading edge of the left wing. The strike appears to have occurred on or relatively close to the wing glove near the Orbiter fuselage. After striking the left wing the debris broke into a spray of white-colored particles that fell aft along the underside of the Orbiter left wing. ……….. -------- End quote --------- However, in all the news conferences the debris was said to have struck the underside of the wing. http://home.infi.net/~blueblue/_uimages/pi.gif |
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The figure below is from a paper “Risk Management for the Tiles of the Space Shuttle” by Elizabeth M Pate-Cornell and Paul S Fischbeck, written Jan-Feb, 1994.
The darkest areas in this figure are concluded to be the highest risk areas, and are located on the fuselage near the wing glove. The report noted that the highest risk areas were not the hottest areas. The estimated risk was made up of a combination of many factors including the chances of debris from the main tank hitting the Shuttle, where they would hit, the chances they would damage a tile, and the consequences of a burn through to equipment underneath. The study seems to have been limited to tiled areas (i.e. it didn’t cover the carbon leading edges). http://home.infi.net/~blueblue/_uimages/Risk.gif I do not understand why this figure is not symmetrical in either its outline or in the shading representing risk. I assume the diagram represents the bottom surface only. If so, the left fuselage/glove area is actually somewhat less vulnerable than the right. I don't what other people think, but in the vidio I have seen the debris does NOT seem to hit the fuselage at all. http://home.infi.net/~blueblue/_uimages/pi.gif |
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