GE.LJB@forsythe.stanford.edu (Louis J Bookbinder) (01/01/91)
Jack Houde says: >This may have been answered before but... > >Since the beginning of manned space flight, what happens to >the water that is dumped during flight? > >In the case of the Shuttle, is it close enough to Earth to >cause it to re-enter? Else, does it become a frozen mass of >whatever, forever stuck in orbit? > >Or is it simply that they figure we have enough of it that >it can be thrown away without any thought? Water in the Shuttle is under ambient (artificial) atmospheric pressure. Under pressure, there is a temperature range in which water is a liquid. However, at a very low pressure, this does not occur. When expelled from the Shuttle, the pressure drops below the critical pressure for liquid water to occur. Water can then exist only as either a solid or a gas. The gas rapidly dissipates. The solid (ice) is much more stable, but at temperatures (and thermal irradiance levels) near the earth, the ice has a small, non-zero vapor pressure, and thus evaporates. The expelled water will thus evaporate AND freeze at the same time, somewhat explosively, and then the ice will evaporate at a more leisurely pace. The vapor will soon become indistinguishable with the interplanetary medium (except that water is rare) at least as far as density is concerned. What happens to the solids is an entirely different matter. Excreted dissolved chemicals will quickly be exposed to vacuum, where some will vaporize and others will become solid, stable residues. Solids (excrement, etc) will remain solid (and completely dehydrated) but then become exposed to various kinds of radiation. Long-term effects unknown. Does the Shuttle just dump human wastes, or does it filter out the solids? Almost anything lost from the Shuttle (except gases) eventually returns to earth, the LEO the Shuttle uses is in a region of non-negligible drag. Some things take longer than others to fall, however. Imagine hitting some solid refuse at 25Kkph. "What happened, Columbia? " "Well, Kennedy, seems we hit a piece of (deleted) and it took out number 4 window!" Smell would not be the problem. Louis Bookbinder GE.LJB@Forsythe.Stanford.Edu 725-0639
henry@zoo.toronto.edu (Henry Spencer) (01/01/91)
In article <1990Dec31.204130.2390@morrow.stanford.edu> GE.LJB@forsythe.stanford.edu (Louis J Bookbinder) writes: >Does the Shuttle just dump human wastes, or does it filter out the >solids? US manned missions have never dumped solids; only liquids go overboard. -- "The average pointer, statistically, |Henry Spencer at U of Toronto Zoology points somewhere in X." -Hugh Redelmeier| henry@zoo.toronto.edu utzoo!henry