Auxiliary Power Unit venting. It is basically burning off excess gases and preventing the overheating of the APUs during landing. The APUs are what power the shuttle and control the bird during re-entry. They've been shown on several night landings (usually via the infrared camera) but this landing was more noticeable than others. Apparently the PAO had to mention it because commentators for CNN (international, US didnt cover it) and FoxNews were commenting about the "onboard fire". Venting always occurs after landing, you don't see it on a daytime landing. More about the APUs are found here: http://spaceflight.nasa.gov/shuttle/reference/shutref/orbiter/apu/ From this page (Boeing): http://www.boeing.com/defense-space/space/hsfe_shuttle/sts1/recollections.html The Shuttle APU is similar to the F-16 emergency APU. Both are single disk turbines that are powered by decomposing hydrazine. The Shuttle APU pulses fuel to control the power output and the F-16 runs the fuel through it at a constant rate and the excess gas is vented out of a bypass port. The technology has been around quite a while -- very reliable. The only novel feature of it was the way you fed fuel into it Greg Williams On Thu Mar 27 9:30 , "amstuart" sent: > Hi: > > At first I thought a strobe light was flashing near the tail fin of the > shuttle as it rolled to its night landing. Then, when the orange glow >became > more intense, I thought the shuttle was on fire (!) Finally, a commentator > on NASA TV stated that APU venting was causing this dramatic image. >What is "APU venting", and why are flames apparently released and not mere > heat if the term "venting" is used? Is "venting" something that takes place > on-orbit (ever) and is visible from Earth? > > Thank you. > >Adam > >------------------------------------------------------------------------- >Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: >http://www.satobs.org/seesat/seesatindex.html > ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
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