dietz@SLB-DOLL.CSNET (Paul Dietz) (02/01/86)
The NY Times today (2/1/86) reports that telemetry indicates the right (far) SRB experienced a 4% drop in thrust and a 30 lb/in^2 drop in pressure starting 10 seconds before the explosion. The main engines and SRB nozzles were swivled at that time to try to compensate. Also, telemetry indicates the main engines stopped several seconds before the explosion, apparently because the oxygen line running down the side of the ET was cut. My guess of the course of the accident is this: (1) the right SRB was faulty, (2) when the burn-though on the side of the SRB occured (either because of cracked propellant or casing) a jet of hot gas hit the ET near the oxygen line, (3) it took several seconds for the insulation and metal to burn through, (4) when the oxygen line went gas began escaping and perhaps the tank structure itself (aluminum) burned in the hot oxygen gas, (5) just before the explosion the flames may have set off the range-safety charges on the ET, allowing the fuels to mix and explode. This could explain the small explosion that occured several frames before the big blast. It looks like proper software could have saved the shuttle. The proper course would have been to jettison the SRB's as soon as one acted up. Unfortunately, SRB's have varying thrust, so perhaps NASA didn't want to jettison one for just a 4% variation. Even so, the shuttle could have tried to get away when all the main engines failed, although it's not clear enough time remained for it to get clear. Does anyone know if the shuttle was in a position to return to Kennedy, or did it already have too much lateral velocity to glide back on its own? Also, how close is the oxygen line to the right SRB? If it runs down the right side of the ET this could be considered a serious design error (similarly for the range safety charges).
joels@tekred.UUCP (Joel Swank) (02/05/86)
> It looks like proper software could have saved the shuttle. The proper > course would have been to jettison the SRB's as soon as one acted up. > Unfortunately, SRB's have varying thrust, so perhaps NASA didn't want > to jettison one for just a 4% variation. Even so, the shuttle could > have tried to get away when all the main engines failed, although it's > not clear enough time remained for it to get clear. The SRBs cannot be jettisoned before burn is complete, and burn cannot be stopped. One astronaut was quoted as saying: "If the SRBs fail, it's just curtains."
ray@rochester.UUCP (02/07/86)
> > Does anyone know if the shuttle was in a position to return to Kennedy, > or did it already have too much lateral velocity to glide back on its > own? Also, how close is the oxygen line to the right SRB? If it runs > down the right side of the ET this could be considered a serious design > error (similarly for the range safety charges). According to a NASA spokesman, there is virtually no chance of successfully aborting the mission until the SRBs have used up their fuel and are jettisoned. NASA has no viable abort plans for the shuttle until the SRBs have been normally jettisoned. Until this point in the liftoff, the shuttle is too low to return to Kennedy and would have to ditch in the Atlantic at a speed of 220 mph +. At this speed, NASA believes the shuttle would break up on impact and sink rapidly. NASA also believes it is unlikely the shuttle would escape serious damage from the exhausts of the SRBs as it jettisoned them while they were still functioning at full power. I'm not sure of this, but several days ago I thought I read where NASA had bits of debri from one of the SRBs that showed the exploding bolts had not been activated indicating no attempt by the crew to jettison the SRBs. Has anyone heard any more on this? An earlier posting surmised the reason the SRBs escaped the explosion intact was because they were jettisoned by the crew moments before the explosion. ray
jlg@lanl.UUCP (02/07/86)
In article <440@tekred.UUCP> joels@tekred.UUCP (Joel Swank) writes: > The SRBs cannot be jettisoned before burn is complete, and burn cannot >be stopped. One astronaut was quoted as saying: "If the SRBs fail, it's >just curtains." All the reports I've heard say that the SRBs and the ET *CAN* be seperated before the burn is complete. It's just a matter of throwing a switch and pushing a button (arm and fire I would guess). The only problem is, no one knows whether the Shuttle can survive the trip through the SRB exhaust plumes or whether the ET may fold up under the change of stress. Trying to seperate early might cause the same kind of explosion as they were trying to avoid. These, at any rate are the facts according to the Shuttle test pilot interviewed by CBS. J. Giles Los Alamos