Iss fuel reserve

"Jeff Findley" wrote

Sure, you just launch with enough oxygen, water, and food to last the
duration of the flight. How much food, water, and oxygen is needed per
person day is something that is well understood by NASA.

About 25-30 kg/day-person, no?

There are few times when I have a chance to correct Mr. Frank on this
subject, but let me add some comments below:

"Jorge R. Frank" wrote in message ...
(Allen Thomson) wrote in
:

(Explorer8939) wrote

There is indeed a formal requirement, expressed in the number of days
left before would ISS drift down to 250 km, which would be the point
of no return. The requirement increases after Flight 12A. In both
cases, the propellant requirement is actually an orbital maintainence
requirement, from which prop can be derived.

Thanks much.

The actual number is wrong, though - it's 150 n.mi., or 277.8 km (usually
rounded to 280 km).

Because of the impending solar minimium, prop is not really an issue,
water is the problem.

It seems ironic that water, which a naive person (e.g., I) would
think to be the poster child for a recoverable/renewable resource,
should be the long pole in the tent. Is it planned to develop
closed-cycle life support systems as part of the post-completion
ISS science plan?

Lots of proposals kicking around, AFAIK nothing funded yet.

SpaceHab got a $200K contract to look a urine processing system a
couple of years ago, but the big bucks have been spent on Node 3
ECLSS. Unfortunately, the funding has been stop and go, and the latest
news looks like they are talking about stuffing the ECLSS in the Lab.

Speaking of the upcoming solar minimum, one notes from the somewhat
gaudy http://science.nasa.gov/ssl/pad/sola..._predict_l.gif
that the following maximum is due at the end of the decade, right
around the planned Shuttle retirement date -- presumably the last
Shuttle flights will leave ISS at 400 km altitude and fully tanked
up?

Most likely. They can't go much higher - the rendezvous ceiling for
Soyuz/Progress is 410 km.

Off the top of my head, I believe the numbers a docking ceiling for
Soyuz/Progress is 425 km, departure ceiling is 460 km (ie the highest
altitude at which these craft can safely leave ISS and return to
Earth).

On 2004-07-23, Allen Thomson wrote:
"Jeff Findley" wrote

Sure, you just launch with enough oxygen, water, and food to last the
duration of the flight. How much food, water, and oxygen is needed per
person day is something that is well understood by NASA.

About 25-30 kg/day-person, no?

Zubrin gives "NASA standard figures" (although slightly modified by him)
as:

4kg potable water, 1kg whole food, 0.5kg dried food, 1kg oxygen, 26kg
washing water.

The 1kg whole food, he notes, is a change from 0.13kg dehydrated food -
he doesn't say if he also adjusted the potable water figure to go with
it, but notes that with decent recycling it likely balances out.

So about 30kg/person/day, mostly through washing water, before any
recycling happens - which will make significant inroads. This doesn't
cover other consumables, mind you; clothing, pressurisation gases for
the air...

--
-Andrew Gray

Andrew Gray wrote:
Zubrin gives "NASA standard figures" (although slightly modified by him)
as:
4kg potable water, 1kg whole food, 0.5kg dried food, 1kg oxygen, 26kg
washing water.

I would question the 26kg washing water though. On ISS, there is no "shower".
They use russian pre-hydrated towels to wash. 26 litres of water is a hell of
a lot.

Also, and more importantly, the ISS does collect water from humidity in the
air. So the water that evaporates from the wet towels makes it back to the
condensors and is then re-used.

On 2004-07-24, John Doe wrote:
Andrew Gray wrote:
Zubrin gives "NASA standard figures" (although slightly modified by him)
as:
4kg potable water, 1kg whole food, 0.5kg dried food, 1kg oxygen, 26kg
washing water.

I would question the 26kg washing water though. On ISS, there is no "shower".
They use russian pre-hydrated towels to wash. 26 litres of water is a hell of
a lot.

He did comment that this was a very generous allocation. However,
"showers" have been flown before, on Skylab; this may be where the
figure came from. (or from Freedom design documents? Herb might have an
idea, he was an ELCSS type).

http://www.centennialofflight.gov/es...lab/SP23G4.htm
http://grin.hq.nasa.gov/ABSTRACTS/GPN-2000-001710.html

has a couple of pictures, Skylab 2 & 3 respectively.

Also, and more importantly, the ISS does collect water from humidity in the
air. So the water that evaporates from the wet towels makes it back to the
condensors and is then re-used.

Indeed, this is where your recyling factor kicks in. (Zubrin's estimate
was that 90% was achievable without great efforts being taken, IIRC -
washing water does have lower standards than potable, so...)

--
-Andrew Gray

Note that the Russians did try to fly showers aboard Salyut and Mir,
and finally gave up on the idea.



John Doe wrote in message ...
Andrew Gray wrote:
Zubrin gives "NASA standard figures" (although slightly modified by him)
as:
4kg potable water, 1kg whole food, 0.5kg dried food, 1kg oxygen, 26kg
washing water.

I would question the 26kg washing water though. On ISS, there is no "shower".
They use russian pre-hydrated towels to wash. 26 litres of water is a hell of
a lot.

Also, and more importantly, the ISS does collect water from humidity in the
air. So the water that evaporates from the wet towels makes it back to the
condensors and is then re-used.