Does anyone have any theories as to how this phenomenon occurs?

Observers on earth - and more interestingly - on the International Space Station have filmed clouds that literally are on the edge of space.

These so called noctilucent clouds are at an altitude so high, there is no real explanation as to how they get there since there is no known way of transporting them.

NASA footage can be found here (http://spaceflight1.nasa.gov/gallery/video/station/expedition7/ndxpage5.html)

These so called noctilucent clouds are at an altitude so high, there is no real explanation as to how they get there since there is no known way of transporting them.
While we do not know with certainty how these are formed it is quite misleading to say "there is no real explanation as to how they get there since there is no known way of transporting them". Here is a perfectly plausible explanation centred on ice crystals.

http://www.meteo.helsinki.fi/~tpnousia/nlcgal/nlcinfo.html

The only thing I could think of is that the clouds are shaped in a way that the "flew" to the top. Kind of like a plane weighs a lot, but given the right shape and speed it flies. I dunno, and it seems like NASA doesn't know either.