miller@uiucdcs.UUCP (miller ) (11/29/83)
#N:uiucdcs:8500008:000:256 uiucdcs!miller Nov 28 14:33:00 1983 Watching the launch on CNN this morning, I observed something I have never seen before. Smoke appeared on the top of the SRB's about 30 sec. into the launch. I assume this was some form of contrail. Is this usual? (ps: it only lasted for 5 sec. or so.)
ks@astrovax.UUCP (Karl Stapelfeldt) (11/30/83)
The effects that you saw on the nose of both SRB's during the STS-9 launch are due to the passage of the vehicle through Mach 1. What you saw was not smoke, but water vapor rapidly condensing out of the air in the (complicated) shock wave structure around the SRB nose. You can observe the same kind of effect when supersonic aircraft pass through the "sound barrier". The condensation should also be visible about the top of the external tank, if you get a chance to see that video tape again.