Tilelessly Re-Entering the Shuttle Story


You may be able to do me (and yourself perhaps) a favour by passing this on to any/all and or other MSNBC journos (or other such ilk of your wide acquaintanceship).....or any NASA STS-related contacts that you may happen to have. It relates to the series of Columbia crash (and STS re-launch) articles linked below. As you may (or may not) have noted, NASA is finding it very hard to implement any sort of viable in-orbit repair plan that could assist future Shuttle crews in getting their launch-damaged ship ship-shape for de-orbit. In fact they've totally given up on that aspect. The reasons why are given in the articles linked below (and the one repeated below my letter to NASA's Shuttle Manager Bill Parsons -hereunder). Basically NASA is getting the cart before the horse in concentrating upon in-orbit "repair" instead of "avoidance". Without being tiresomely repetitive, my theory has it that a 1.25" to 1.5" thick conformal coating of Silastic (tapering down to zero thickness well behind the leading edges [above and below the wings- and also on the leading edge of the vertical stabilizer] would protect against the sort of debris hit Columbia took on launch.

Said protective "glove" would be designedly "sacrificial" in that it would only have to survive the low Mach Nos and dynamic q of launch yet quickly and readily burn away (ablatively or incendiary) upon re-entry heating. It would not affect the Shuttle's aerodynamics or CG on launch...or add more than minimal weight. At worst it should limit the lateral extent of any RCC tile damage and perhaps afford a "repairable hole (rather than an unmanageable gaping void).  Dow Corning have already said that they have a suitable Silastic that would adhere (then disappear upon re-entry). That would in theory preserve the integrity of the very brittle RCC (reinforced carbon carbon) wing leading-edge tiles and avoid the sort of process that quickly burnt up Columbia's wheel-well and wing innards. Any direct debris hit upon those very brittle tiles should be deftly deflected by the conformal and resilient Silastic coating (being protectively thickest at the very leading-edge radius).

Mission Implausible? Your task, should you be prepared to accept it, would be to give this theory wider currency whilst as usual protecting my anonymity (but attributing it to IASA). Otherwise another Shuttle sortie may again self-destruct in a matter of a few seconds.

All the debris recovery, angst and investigation efforts would have been for nought (in my mind) if NASA doesn't manage to come up with a "proper" fix. That fix should be based upon the first principle of avoidance (or at last mitigation). The admission thus far is that they haven't been able to resolve it in any fashion. I doubt that there are any insoluble flaws in my theory and it's anyways possibly worth bouncing off them for another reason. Once they have had it dumped in their laps by the media they'd find it hard to use the plausible deniability defence. Allegedly they have discarded their pre-Columbia arrogance on the safety front and are now more than prepared to listen to third and fourth party input. Maybe you can just use this as a test of that stance. Thus far my attempts to get through have been unable to penetrate the standard re-entry comms loss "cone of silence" (so the inutility of futility has led me once again back to you and your resources).

If you manage to get through I'll send you a complimentary Mars bar.


NASA Abandons Rigid Overwrap For Patching RCC Holes

After encountering "significant technical challenges," NASA is abandoning attempts to develop a rigid overwrap to patch large holes in the space shuttle's reinforced carbon-carbon (RCC) panels in the event of damage during flight, and instead is pursuing other methods that probably won't be ready in time for the shuttle's return to flight, according to agency officials.

The shuttle program plans to fly again in March or April of next year. The Columbia Accident Investigation Board (CAIB) specified that NASA must develop methods of on-orbit thermal protection system (TPS) inspection and repair for the shuttle before that flight. Columbia was lost after foam debris from its external tank punched a large hole in one of the orbiter's RCC leading edge panels.

"The biggest problem with any of the TPS repair techniques [is preserving the] outer mold line," Shuttle Program Manager Bill Parsons said during a teleconference Aug. 3. "The second [problem] is how do we connect something like that to the wing?"

Another problem is the variable geometry of the 22 RCC panels that run along the leading edge of each wing, no two of which are the same. "You'd have to make a wrap that would fit with that geometry, because that outer mold line is so important," Parsons said. "So you end up having to build a number of these panels that would be able to fit in the exact right place on the wing."

Instead, NASA is trying to develop a flexible overwrap with new materials, but this solution will not be ready in time for first flight. Other concepts such as sealing the hole with a ceramic filling also are being considered.

Implementation plan

The latest version of NASA's implementation plan for returning the shuttle to flight was released Aug. 3. For fiscal year 2005, a

Technicians Jake Jacobson and Billy Barecka install a reinforced carbon-carbon panel on the right wing of the space shuttle Discovery at NASA's Kennedy Space Center. Discovery is due to take the first shuttle flight since last year's Columbia tragedy.

total of $643 million in return to flight initiatives has been approved or is under review, up from a January estimate of $238 million, according to the plan. Better estimates should be available by the fall, NASA said. The agency expects to spend a total of $465 million on return to flight in FY '04, compared with January's estimate of $265 million.

The shuttle and International Space Station (ISS) programs have completed analysis showing that for at least the first two flights following return to flight, if damage is discovered on a shuttle that prevents it from re-entering, it would be possible to launch a rescue mission within the window of time during which the first shuttle crew can be sustained aboard the ISS (DAILY, Feb. 20).

According to John Casper, deputy of NASA's Return to Flight Planning Team, the shuttle program has "conditionally closed" five of the 15 CAIB recommendations that the agency must implement before returning to flight. The Stafford-Covey Return to Flight Task Group has been charged with assessing whether or not NASA has fulfilled the recommendations.

The five recommendations are:

* Develop and implement a comprehensive inspection plan for all RCC panels, using nondestructive evaluation techniques

* Modify the agreement with the National Geospatial-Intelligence Agency (NGA) to make the imaging of each shuttle while in orbit a standard requirement

* Require that at least two employees attend all final closeouts and intertank area hand-spraying procedures

* Kennedy Space Center Quality Assurance and shuttle prime contractor United Space Alliance (USA) must return to the industry-standard definition of "foreign object debris" and eliminate any alternate or statistically deceptive definitions like "processing debris"

* Develop an interim program of closeout photographs for all critical subsystems that differ from engineering drawings, and digitize the system so that images are available immediately for on-orbit troubleshooting.

The shuttle program also has closed out several other CAIB recommendations not specifically related to return to flight, according to Casper, and has made significant progress toward eliminating all sources of debris from the external tank. "We have made significant progress also in understanding the ascent debris environment and the material characteristics of the TPS, which includes both the tile and the RCC," he said.

Casper said the shuttle program also is proceeding with a long-term plan for hardening the orbiter against debris impacts, which is the subject of another CAIB recommendation. The first phase of this plan includes measures such as adding insulation to the shuttle's front wing spars, changing the carrier panel bolts for forward RCC panels, eliminating corner voids in the main landing gear doors and adding stronger orbiter windows.

So what was their specific capability for in orbit repair? Click here



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