Thanks Wayne. Does that mean the nozzles are not recovered? When I first heard someone describe using divers to manually insert a plug in the SRBs I thought they were kidding. Surely, I thought, NASA must use a more high tech way of doing it. But then I saw the pictures. Sometimes low tech works just fine (just ask the Russians and the 50+ year old design of their boosters). Regarding your last sentence, the piece on Science Friday I referenced earlier noted that with all the data NASA has now, they calculate the the odds of losing an orbiter early in the program were 1 in 10 or even 1 in 9. patrick p.s. I still want to go... On 07 Mar 2011, at 00:06, WAYNE S CLARKE wrote:
I don't know whether the question about what was apparently a "pyrotechnic" event just before the spent booster hit the water has been answered or not, but that is what it is.
Last May I went to Florida and got to watch the launch of STS132, Atlantis, with a group from ATK Thiokol. A couple of days later we watched them tow the spent boosters back to the NASA facility to be disassembled and examined before they were returned to Utah to be refurbished and reused. The pyrotechnic you noticed and the object you saw hitting the water just before the spent booster hit the water was the nozzle itself. It is blasted off the end of the booster because the engineers say that the heavy nozzle would make it likely that the spent booster would hit the water nozzle first, if it were still attached. They think that if it hit water straight on, nozzle first, the shock would do so much damage to the rocket casings that they would not be able to re-use them. With the nozzles gone from the end of the boosters, divers have to insert plugs into the end of the boosters before they sink. When the plugs are in place, the boosters can be secured horizontally to the side of the ships which tow them back. Even this minuscule detail of the retrieval of the spent boosters is another very complex problem which needs to be attended to and it is nothing in the total scheme of things. I don't know how any of the shuttle flights are ever successful.