What are those white flakes that can be seen on old footages falling from rockets during lift-off? Paint, insulation? It looks disturbing but I suppose its normal…
I believe it’s ice.
Doubtless someone else more knowledgeable will come along to confirm or deny.
Ice at Cape Canaveral, Florida?
Ice on the outside of a fuel tank filled with liquid … umm… cold rocket fuel. Hydrogen? Oxygen? Anyway. Really cold.
Liquid oxigen for the oxidant on the first and second stages, the fuel was kerosene AFAIK.
It makes sense - but Space Shuttle’s External tanks should have the same problem but I don’t remeber seeing ice falling from them - maybe beacause of some thermal protection coating, something that didn’t exist during Apollo era?
Yep. They’ve got insulation on the Shuttle’s tank.
You’re not paying attention. The shuttle Columbia was destroyed by a piece of ice that fell off the external tank during launch & tore a hole in the wing.
The insulation on the external tank is intended to reduce ice formation and hence ice shedding, but it aparently didn’t really work all that well. A lot of the delay in getting the shuttles going again is caused by the difficulty of preventing ice formation on a very large, very cold surface (the tank) sitting in a very humid environment (the Florida seashore).
Just to clarify, the “you” I was referring to was geonetix; we had a triple simulpost there.
Ice? Hmmmm, IIRC a chunk of insulation from Columbia’s external fuel tank broke loose and struck the wing’s heat-resistant tiles. I remember NASA officials waving with similar chunk at press conference…
It was indeed a piece of insulation foam, not ice, which damaged Columbia. Ice is a problem for the shuttle though, but it’s much less prominent than on the Saturn V.
The white stuff falling off Saturn V (and other) rockets was, indeed, ice that had formed on the outside of tanks containing things like liquid oxygen, which is very, very cold.
The thing that nailed the Columbia wing was, indeed, a chunk of insultation falling off a fuel tank. Insulation intended to prevent large chunks of ice from forming and falling off and maybe causing damage.
Yes, ice in Florida IS a problem for NASA. As can be seen, both the ice itself and some of the proposed solutions for the problem can both cause serious problems.
I don’t think that the STS-107 investigation was able to establish the precise composition of the impactor. Certainly the insulating foam was involved, but it may also have been saturated with ice:
Columbia Accident Investigation Board Press Briefing (Mar 26, 2003)
Since the initial question has been answered (those white flakes were ice particles) I consider this thread exhausted. Thank you everybody very much, indeed - let’s now all move on to harder questions… 
You mean questions like “how high is up” and “what is the sound of one hand clapping” and “do ursines defecate in arboreal areas”?
For that matter, one of the major contributing factors to the Challenger disaster was cold weather that the launch site had had a few days before, which caused one of the rubber O-rings to become brittle. So there’s even problems with ambient cold in Florida, not caused by the rocket itself.
The problems with Skylab were due to ice creating a lever that pulled the heat shield off. I can’t remember if this was due to the liquid oxygen, or standing water that froze, though.