jack@focsys.uucp (Jack Houde) (12/20/90)
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?
heskett@titan.tsd.arlut.utexas.edu (Donald Heskett) (12/20/90)
At earth's distance from the sun, water ice should sublimate fairly rapidly. Just look at what happens to comets! I would guess that a one-inch sphere would sublimate away in a week or two.
jimcat@itsgw.rpi.edu (Jim Kasprzak) (12/20/90)
In article <1990Dec19.172159.15458@focsys.uucp> jack@focsys.UUCP (Jack Houde) writes: >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? I'd guess that it becomes a frozen mass of whatever that either sublimates away to vapor, or decays in orbit to vaporize on re-entry. > >Or is it simply that they figure we have enough of it that >it can be thrown away without any thought? This is indeed the case. The amount of water that goes up on any spaceflight is infinitesimally small compared to the amount of water on Earth. We're not going to run out any time soon. -- Jim Kasprzak kasprzak@mts.rpi.edu (internet) RPI, Troy, NY userfe0u@rpitsmts.bitnet "A spirit with a vision is a dream with a mission." -Rush
jdishaw@cbrown.claremont.edu (Pom Ac Comp Staff) (12/21/90)
I know some of the water waste from the fuel cells gets reclaimed for use by the astronauts as their water supply and the rest gets dumped. Why don't they split the water back into hydrogen and oxygen and use it for the fuel cells again? I know this isn't 100% efficient process, but I would think there would be some benefits. James R. Dishaw
dil@mace.cc.purdue.edu (Perry G Ramsey) (12/21/90)
In article <10212@jarthur.Claremont.EDU> jdishaw@cbrown.claremont.edu writes: >I know some of the water waste from the fuel cells gets reclaimed for use >by the astronauts as their water supply and the rest gets dumped. Why >don't they split the water back into hydrogen and oxygen and use it for >the fuel cells again? I know this isn't 100% efficient process, but I would >think there would be some benefits. Let me define a couple of terms, as they are used by the program: Waste water: Urine and condensed cabin humidity. Unfit for human consumption. Potable water: Water generated by the fuel cells. It is suitable for drinking. What is going to be used to split the water molecules? Electricity. How are you going to generate it? From combining hydrogen and oxygen in the fuel cells! The potable water generation rate is entirely a function of the electricity generation rate. By this I mean that there is more water generated due to electrical requirements than can be used. The only thing you can do is get rid of the excess water. If you put some solar panels on the shuttle (something deployable from the payload bay) you could use that electricity and reduce fuel cell useage in the first place. Since cryogenic consumables (liquid hydrogen and liquid oxygen to run the fuel cells) are the current flight limiting factor, an extra source of electricity like this could substantially extend the flight. Unless you have a better idea on how to split water molecules. -- Perry G. Ramsey Department of Earth and Atmospheric Sciences perryr@vm.cc.purdue.edu Purdue University, W. Lafayette, IN USA dil@mace.cc.purdue.edu Why waste time learning when ignorance is instantaneous? -- Hobbes
jdishaw@cbrown.claremont.edu (Pom Ac Comp Staff) (12/21/90)
In article <10212@jarthur.Claremont.EDU>, jdishaw@cbrown.claremont.edu (Pom Ac Comp Staff) writes... >I know some of the water waste from the fuel cells gets reclaimed for use >by the astronauts as their water supply and the rest gets dumped. Why >don't they split the water back into hydrogen and oxygen and use it for >the fuel cells again? I know this isn't 100% efficient process, but I would >think there would be some benefits. > >James R. Dishaw I forgot to mention one thing in this post, that some people pointed out to me. To get the power to do this, they could tie into the shuttle's power bus, a solar panel, or possibly a thermocouple. James R. Dishaw
mears@hpindda.cup.hp.com (David Mears) (12/21/90)
> / jdishaw@cbrown.claremont.edu (Pom Ac Comp Staff) / 8:42 am Dec 20, 1990 / > > I know some of the water waste from the fuel cells gets reclaimed for > use by the astronauts as their water supply and the rest gets dumped. > Why don't they split the water back into hydrogen and oxygen and use it > for the fuel cells again? I know this isn't 100% efficient process, but > I would think there would be some benefits. > > James R. Dishaw It seems to me like it would be a self-defeating process. In order to split it up again, you need energy. To get the energy, you run the fuel cells which produce more water. Because it takes more energy to split than you get when you recombine, you end up with more water than you started with. As they say, 1) you can't win, 2) you can't break even, 3) you can't get out of the game. David B. Mears Hewlett-Packard Cupertino CA hplabs!hpda!mears mears@hpinddf.cup.hp.com
gary@ke4zv.UUCP (Gary Coffman) (12/21/90)
In article <10212@jarthur.Claremont.EDU> jdishaw@cbrown.claremont.edu writes: >I know some of the water waste from the fuel cells gets reclaimed for use >by the astronauts as their water supply and the rest gets dumped. Why >don't they split the water back into hydrogen and oxygen and use it for >the fuel cells again? I know this isn't 100% efficient process, but I would >think there would be some benefits. > >James R. Dishaw Did you read this before you posted? Where, pray tell, would they get the electricity to split the water back to hydrogen and oxygen, carry a really long extension cord maybe? The reason the fuel cells produce water is that they are "burning" hydrogen and oxygen to generate power used on the shuttle. If they don't need any excess electricity, they don't make any, or create any water. There's no "waste" electricity on board to be used to split water. What you are suggesting is equivalent to saying that you should use electricity from your car battery to recharge your car battery. Gary
phil@brahms.amd.com (Phil Ngai) (12/28/90)
In article <10213@jarthur.Claremont.EDU> jdishaw@cbrown.claremont.edu writes: |I forgot to mention one thing in this post, that some people pointed out to |me. To get the power to do this, they could tie into the shuttle's power |bus, a solar panel, or possibly a thermocouple. And where does the shuttle's power bus get its power? From the fuel cells? "There's a sucker born every minute!" -- Whatever happened to Global Warming? Could we have some Local Warming?
henry@zoo.toronto.edu (Henry Spencer) (12/28/90)
In article <1990Dec19.172159.15458@focsys.uucp> jack@focsys.UUCP (Jack Houde) writes: >Since the beginning of manned space flight, what happens to >the water that is dumped during flight? It fairly quickly ends up as individual molecules, through direct boiling of liquid and sublimation of ice crystals. At that point it becomes part of Earth's atmosphere, and vanishes into the vast amounts of water there already. (Well, the water dumped by the Apollo lunar missions ended up as part of the Sun's atmosphere, since Earth's atmosphere only goes out a few tens of thousands of kilometers, but the same general comments apply.) >Or is it simply that they figure we have enough of it that >it can be thrown away without any thought? Earth loses far more water every day by natural processes. -- "The average pointer, statistically, |Henry Spencer at U of Toronto Zoology points somewhere in X." -Hugh Redelmeier| henry@zoo.toronto.edu utzoo!henry
henry@zoo.toronto.edu (Henry Spencer) (12/28/90)
In article <10212@jarthur.Claremont.EDU> jdishaw@cbrown.claremont.edu writes: >I know some of the water waste from the fuel cells gets reclaimed for use >by the astronauts as their water supply and the rest gets dumped. Why >don't they split the water back into hydrogen and oxygen and use it for >the fuel cells again? ... It would be possible if there were some other energy source available, e.g. solar arrays. At present, there isn't. Even if there were, it would be a relatively complex process; for example, the hydrogen and oxygen from an electrolysis cell have a fair bit of water vapor in them, which has to be removed before you do anything useful. It's not impossible; at one point the space station was going to get its maneuvering/reboost fuel by electrolyzing waste water. -- "The average pointer, statistically, |Henry Spencer at U of Toronto Zoology points somewhere in X." -Hugh Redelmeier| henry@zoo.toronto.edu utzoo!henry
pjs@euclid.jpl.nasa.gov (Peter Scott) (12/29/90)
In article <1990Dec19.172159.15458@focsys.uucp>, jack@focsys.uucp (Jack Houde) writes: > 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? The water separates into little ice balls that bombard the atmosphere at random intervals, providing a distinct "cometesimal" UV signature that can be photographed by satellites, and... oh my God... :-) :-) :-) :-) -- This is news. This is your | Peter Scott, NASA/JPL/Caltech brain on news. Any questions? | (pjs@euclid.jpl.nasa.gov)