posted 07-04-2006 02:46 PM               

Granted, at this point in flight, I think airflow over the orbiter is thin enough that any piece breaking off will do much less damage than it would if it happened before SRB sep. Griffin said to expect shedding, but it should be of the nature that it wouldn't damage the orbiter. The piece moved a lot slower than the one you see in the Columbia footage.

I think the liklihood of ever seeing a perfectly "clean" launch is close to zero. There will always be some shedding.

Having that ET tank camera is a mixed blessing. It shows sheding events very clearly. But any shedding event witnessed by the public can be taken the wrong way.

posted 07-04-2006 03:15 PM               

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Originally posted by mjanovec:
Having that ET tank camera is a mixed blessing. It shows sheding events very clearly. But any shedding event witnessed by the public can be taken the wrong way.

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There will be a media briefing tonight with Wayne Hale wherein he plans to share the initial imagery analysis. Its too early right now to say what, if anything was seen by the ET camera (and others) and what, if any impact it might have on the mission.

posted 07-04-2006 04:20 PM               

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A camera mounted on the shuttle's external tank provided spectacular views of the spaceship's heat-shielded underside as Florida's east coast dropped away in the background. The ascent appeared free of foam debris from the tank until about two minutes and 47 seconds when a half-dozen seemingly small pieces of debris could be seen suddengly separating. NASA managers said before launch that foam debris shedding after about 165 seconds was of no concern because by that point, the atmosphere is so thin it cannot carry debris to a dangerous impact. The debris seen today separated around 167 seconds after launch.

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posted 07-04-2006 05:02 PM               

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managers say that engineers already have noted foam loss in two separate incidents. Shuttle program manager Wayne Hale said three or four small objects appear to break off the tank about 2 minutes, 47 seconds into flight. Then more debris is seen liberating from the tank about 4 minutes, 50 seconds after launch.

However, Hale said, both incidents occurred when the shuttle was high above Earth with little atmosphere. The lack of air means that the foam could not gain enough speed to damage the spaceship if it struck it.

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posted 07-04-2006 07:35 PM               

Further, Hale said that they know with certainty that four out of the five events involved fragments that were below the size threshold that are of concern (the fifth may very well be too, but they need to wait for better imagery to be downlinked to determine that with the same degree of certainty).

Per Hale, these events were within NASA's expectations of the tank's performance and though the crew will proceed with the full inspection of Discovery's heatshield (using both the orbital boom inspection system and the "back-flip" maneuver before docking with the ISS) they have little reason for concern.

One piece of debris did appear to "touch" the orbiter, but its lack of velocity and more importantly, its lack of being obliterated in the process (nor any color change to the area of the "touch" on the orbiter's belly) has led Hale and his team to be certain that no damage was caused.

The "blanket" filmed and reported by MS Mike Fossum is, in fact, ice that formed around the bell(s) of the space shuttle main engines. Hale has seen this before (most recently on STS-114) and if you watch the video, you can clearly see the ice breaking apart, the result of sublimation.

Lastly, the reports of flapping ice frost ramps and/or paper are the result of both confusion with the paper RCS jet covers falling off (as they are designed to do) and a video artifact.