Just to make a somewhat un-related comment but I also understand it goes in reverse while in Space, there are other dangers aswell called space debris or space junk, space junk has serious destructive potential a few flicks of paint or garbage almost smashed in the front window on shuttle. So who will start cleaning this dangerous stuff up, the guys at NASA, the Russians should do it, the EU or UN should fund it ? Debris of all sizes can be dangerous, a paint fleck can gouge a shuttle window. Space collisions are frequent enough that NASA on average now replaces a window after each shuttle mission. In one shuttle two windows were replaced and scientists later found 51 pits in them. They contained meteoroids, paint chips, aluminum, stainless steel, silver, copper and plastic, now there is a plan to fly backwards to reduce the chances of exposing vulnerable parts of the craft to debris