QUESTION:
I understand that the length of the human trip to Mars is about 2 to 3 years
long. There should be a control room, an excerise room, living quarters, an
isolation room in case of solar flares, recycling room, storage for food,
water, tools, and medical kits, an entertainment center, a kitchen if there
is artificial gravity, a bathroom, a research facility, and ROVs. What would
be the ideal plumbing, waste management, recycling, and ventilation system
for a 2 to 3 year trip to Mars?

ANSWER from Kent Joosten on July 24, 1997:
There are several technologies we are looking at right now to recycle the
water, air, and food during deep-space missions.  For removing carbon
dioxide from the air, we are looking at a chemical process called a Sabatier
reactor.  This mixes the carbon dioxide with hydrgen gas to produce methane
(which is vented) and water.  the water is then split into hydrogen and
oxygen.  The oxygen is relaeased inot the cabin, the hydrogen goes back in
the system to react with more carbon dioxide.

Foe water recovery, we are looking a devices called bioreactors.  These are
tanks in which we grow particular types of microbes which rapidly break down
urine and dirty water into clean water.

For solid human waste, we are looking at types of incinerators which will
allow us to recapture the moisture and gasses from the feces, leaving very
little solid residue.

Kent Joosten
NASA Johnson Space Center

ANSWER from Andrew Petro on July 24, 1997:
On a trip to Mars which will take many months (using any currently known
propulsion technology) the water will probably be removed from the human
waste and be recycled.  Also, humidity in the onboard air, which comes from
the breath and perspiration of the crew can also be recovered and recycled. 
Other types of waste such as food packaging, paper, etc. will be more
difficult to recycle but there will probably be techniques developed to do
this.  If the materials that are used for packaging and other purposes are
bio-degradable, then it may be possible to use these waste materials in a
system which grows food.  There are a lot of ideas being studied for
closed-loop life support systems.  You might look for information on the
Biosphere 2 Project.  As part of the preparations for long space missions at
the Johnson Space Center, there is a project which involves having people
live inside a completely sealed chamber in which the air and water are
recycled.  They have planned a 90-day stay for four people inside the
chamber for this fall.  A 30-day and 60-day test have already been
completed.

Andrew Petro
Johnson Space Center

ANSWER from Steve Wall on July 30, 1997:
That is a really tough design problem -- all I can do is to give you some
general ideas.  Supply plumbing (providing fresh water) could be mostly
limited to "squeezing" water by pressing on a plastic or rubber bag
containing the water supply using a dry gas like nitrogen.  That makes the
water flow.  If you decide to go without artificial gravity, you would need
to use food and drink containers like they do on the Shuttle.  These are
closed containers that have tubes into which you squeeze water.  Sewer
plumbing could be similar to the Shuttle as well.  It is better described
at:

http://www.hq.nasa.gov/office/pao/QandA/hygiene.html