Smoke from solid rocket boosters

The space shuttle s solid rocket boosters get their thrust from the reaction of aluminum metal with ammonium perchlorate, NH4CIO4, which generates a lot of gas and heat. The billowy white smoke is due to the formation of very finely divided solid aluminum oxide. One of the reactions that takes place is... 

Figure 9.3 The space shuttle Challenger just prior to launch. The arrow points to puff of smoke coming from the right solid rocket booster. (Source Reference 1.)...

A series of puffs of smoke was observed emanating from the 51-L aft field joint area of the right solid rocket booster between 0.678 and 2.500 seconds after ignition of the sh uttle solid rocket motors. 

This smoke from the aft field joint at sh uttle liftoff was the first sign of the failure of the solid rocket booster O-ring seals on STS 51-L. 

---