human overhead

Kent Betts wrote:
I think that the technology to operate life support systems for two 6-month
transits is already available.

The question is MTBF. This will dictate how many copies of hardware you need
to bring along for the trip in order to ensure you have sufficient spare
parts/components. And to determine how many you will need, you need to test
these components for that amount of time and then some to get a meaningful statistic.

A trip to the moon is just a weekend camping trip. You can pack all your
consumables easily and they'll fit in the trunk of your car. And for a short
trip, you won't die if you don't bring along your vitamins, nose hair clipper
or your walkman.

But if you're going on a year long trip with no resupply possible, you either
have to bring along huge quantities of consumables, or find reliable way to
recycle your consumables. And there are many think that you will need on a
year long trip that you wouldn't need on a short trip to the moon.

Extracting water from cabin humidity seems to have shown it is quite reliable.


But there is still no empirical experience with the closing of one loop:
taking the O2 from the exhaled CO2 and combining it with the spare H2 to
recreate the water that will be electrolysed to generate O2 and H2.

There is also a lack of experience in growing plants in space in sufficient
quantities to be of use, but without causing major
humidity/corrosion/mushrooms/moss problems to the rest of the station.


Seems to me that more than ever, they need to review the station's plans to
forget about crystals research and focus on developping/testing technologies
to make life easier in space.


It occurred to me last week that most of the weight could be eliminated by
flying a one-way mission.

It just makes the ship bigger to have the added supplies to last longer. They
may decide to ship the fuel for the return trip ahead and dock with it once in
orbit around mars.

The challenge will be developping good food that won't spoil for that time, or
developping the ability to grow fresh vegetables and then just bring more
"boring" food which will easily last one year.

John Doe wrote:


The challenge will be developping good food that won't spoil for that time, or
developping the ability to grow fresh vegetables and then just bring more
"boring" food which will easily last one year.

Dehydrated food and irradiated food should last for a very long time (If
it weren't for the weight problem canned food would also be
fine...plasic cans?) Heck, I've eaten five-year-old MREs and
ten-year-old C rations, and I'm not all rancid and clotted... I'm
thinking kippered beef jerky for the whole crew, along with those little
cheese and cracker packages in my "Snack Food To The Stars" concept.
The lower gravity of Mars means we should bulk up our crew on the way
there in the interests of their easy mobility on the surface via more
weight for traction- if the gravity is 1/3 Earth's, then the crew should
weigh around 300 pounds each to keep things balanced. Not only that, but
if the ship is spun for centrifugal gravity simulation, then these
"Ballast Boys" will easily allow us to keep things in balance by moving
around. We can starve 'em back down again to Earth-friendly weight on
the way back by not giving them any food for the last month of the trip;
either they will thin down...or revert to cannibalism, and that saves us
size on the return capsule- as the bones of the eaten crew can be cast
into space, to make more room for rock samples.. in fact, having just
_one_ astronaut come back with the samples greatly simplifies
everything, and adds a nice Nietzsche/Darwin feel to the whole project
(which should find high favor with the conservative wing of the
Republican Party) as in some way, we can truthfully say that although
he alone survived the voyage, _all_ the crew are part of him.
Mayhaps this concept could be extended to the whole voyage- we start off
with say 100 people on the ship...and _no_ food....
not only are the "fresh meat" concerns addressed, but the constant
day-to-day struggle to stay alive on the voyage will keep the crew from
become bored and listless; and also assure that the surviving crew that
reaches Mars have cat-like reflexes as well as great strength and
cunning. :-)

Pat
(already at "Mars Traction" weight.)

John Doe wrote in :


But if you're going on a year long trip with no resupply possible, you
either have to bring along huge quantities of consumables, or find
reliable way to recycle your consumables. And there are many think
that you will need on a year long trip that you wouldn't need on a
short trip to the moon.


All the more reason to provide for establishing supply "depots" in Martian
orbit. If you're clever enough, you may even be able to develop a plan for
an in-transit re-supply. Either way, taking everything along with you for
the entire trip is a needless constraint.

--
Reed

In article , John Doe wrote:
Extracting water from cabin humidity seems to have shown it is quite reliable.

The real trick, however, is recycling wash water and laundry water. Those
are the big water consumers for long trips. There have been some limited
demonstrations of such recycling, but it still needs work.

But there is still no empirical experience with the closing of one loop:
taking the O2 from the exhaled CO2 and combining it with the spare H2 to
recreate the water that will be electrolysed to generate O2 and H2.

This is actually a lesser issue, because the sheer tonnage of oxygen
needed is so much less than that of water. On the Martian surface, given
ample power, oxygen can be had in unlimited quantities by solid-electrolyte
cracking of CO2 (CO2 - CO + O2). And it's not unthinkable to just carry
the necessary oxygen for the interplanetary journeys. Recycling would help
but in this case it's not absolutely mandatory.

There is also a lack of experience in growing plants in space in sufficient
quantities to be of use, but without causing major
humidity/corrosion/mushrooms/moss problems to the rest of the station.

And *this* is essentially a non-issue. You simply send a full mission
worth of food supplies along; it's only about 1kg/man/day using dehydrated
foods. Anything you can get by growing plants is a useful supplement, but
with reasonably-sized facilities you probably can't grow a large fraction
of the necessary diet anyway.

Seems to me that more than ever, they need to review the station's plans to
forget about crystals research and focus on developping/testing technologies
to make life easier in space.

Except for details of how well equipment works in free fall, essentially
all the work for this can be done on the ground. There is no need to get
the station involved.

It occurred to me last week that most of the weight could be eliminated by
flying a one-way mission.

It just makes the ship bigger to have the added supplies to last longer.

A lifetime supply of food and spare parts is almost certainly lighter than
a fueled return vehicle. The idea is worth considering.

The challenge will be developping good food that won't spoil for that time...

Available off the shelf in any camping-supplies store.
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |

Henry Spencer wrote:

The real trick, however, is recycling wash water and laundry water. Those
are the big water consumers for long trips. There have been some limited
demonstrations of such recycling, but it still needs work.

That's not hard, just power-intensive. Perhaps too much so for a
non-nuclear mission much past Earth orbit.

But there is still no empirical experience with the closing of one loop:
taking the O2 from the exhaled CO2 and combining it with the spare H2 to
recreate the water that will be electrolysed to generate O2 and H2.

This is actually a lesser issue, because the sheer tonnage of oxygen
needed is so much less than that of water. On the Martian surface, given
ample power, oxygen can be had in unlimited quantities by
solid-electrolyte cracking of CO2 (CO2 - CO + O2). And it's not
unthinkable to just carry the necessary oxygen for the interplanetary
journeys. Recycling would help but in this case it's not absolutely
mandatory.

It's not just a "lesser issue" it's not true. O2 + H20 is simply a fuel
cell when you use cryo liquids. You could very easily do the same thing in
a controlled combustion chamber AND put the waste heat (the reaction is
exothermic, remember?) to some good use while condensing out the water
vapor exhaust for reuse.

SSF's closed-loop ARS ECLSS design was established to demonstrate the
micro-g engineering for most of this very sort of thing fifteen years ago.
Of course, closed-loop ECLSS was one of the first things "deferred" (e.g.,
effectively cancelled) many years ago, although the design as built for ISS
had most or all of the fluid, data and structural connections "stubbed in"
for later addition.


--
Herb Schaltegger, B.S., J.D.
Reformed Aerospace Engineer
Remove invalid nonsense for email.

In article ,
Herb Schaltegger lid wrote:
taking the O2 from the exhaled CO2 and combining it with the spare H2 to
recreate the water that will be electrolysed to generate O2 and H2.
This is actually a lesser issue, because the sheer tonnage of oxygen
needed is so much less than that of water...

It's not just a "lesser issue" it's not true. O2 + H20 is simply a fuel
cell when you use cryo liquids.

I think you've misunderstood. The reaction is not H2+O2-H2O, but either
CO2+H2 - CH4+H2O (Sabatier process) or CO2+H2 - C + H2O (Bosch process).
The former is preferred if a generous supply of hydrogen is available, the
latter if full hydrogen recycling is needed. The point of either is to
get the oxygen out of the CO2 and into H2O, from which it can be recovered
by electrolysis.
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |

Pat Flannery wrote in message ...
The lower gravity of Mars means we should bulk up our crew on the way
there in the interests of their easy mobility on the surface via more
weight for traction- if the gravity is 1/3 Earth's, then the crew should
weigh around 300 pounds each to keep things balanced.

Problem is that then they'd have 300 pounds worth of inertial mass.
Balancing, running, and maneuvering is still harder, because you've
got to generate enough traction to move your inertial mass. As your
mass increases, the traction force your feet are capable of generating
increases, yet the the force required to impart a given acceleration
also increases by an equal proportion. There's no winning.

You'd like to DECREASE your inertial mass, ideally while INCREASING
your traction mass. Gee, I'd like to do that here on Earth.
Unfortunately, the two are inseparable in a given gravity field.
Though I don't know for certain, my guess is that the best
compromise is to maintain a relatively healthy, limber,
agile body weight.

--Rich

Henry Spencer wrote:

In article ,
Herb Schaltegger lid
wrote:
taking the O2 from the exhaled CO2 and combining it with the spare H2
to recreate the water that will be electrolysed to generate O2 and H2.
This is actually a lesser issue, because the sheer tonnage of oxygen
needed is so much less than that of water...

It's not just a "lesser issue" it's not true. O2 + H20 is simply a fuel
cell when you use cryo liquids.

I think you've misunderstood. The reaction is not H2+O2-H2O, but either
CO2+H2 - CH4+H2O (Sabatier process) or CO2+H2 - C + H2O (Bosch process).
The former is preferred if a generous supply of hydrogen is available, the
latter if full hydrogen recycling is needed. The point of either is to
get the oxygen out of the CO2 and into H2O, from which it can be recovered
by electrolysis.

Actually, I don't. I was part of the Space Station Freedom ECLSS ARS design
group during the trade studies trying to choose between the two processes.
The problem with the Sabatier (which ended up winning and being designated
as the baseline) - was that it required a means of venting the excess
methane without violating external contamination requirements. Well, there
was also the power hit, especially early in the assembly sequence.

The main problem with the Bosch process was the much larger power
requirements, combined with all the dev work to ensure that particulate
carbon didn't gum up the works in micro-g, and the fact that you couldn't
just vent carbon dust (which you could do - albeit contaminating the
external station environment - with the methane from the Sabatier reactor).
The carbon would have to be returned periodically from the station along
with the trash.

As a result of a lot of factors, closing the ECLSS loops were never a huge
priority once SSF changed from a stepping stone to Mars and into an end in
itself. With a large enough crew you actually end up positive enough in
your mass balance that you have to vent excess metabolic water, given a
steady supply of fresh food and plenty of O2 from the HPGAs (high pressure
gas assemblies). When you leave LEO and easy access to shuttle-launched
gas and water (metabolized from the fresh food, remember) closing the air
and water ECLSS loops becomes much more important. To do it fully requires
LOTS of power, though. I don't believe anything beyond earth orbit will be
able to do it absent tremendously large solar arrays (much, much larger
than the ISS arrays) or nuclear power.

--
Herb Schaltegger, B.S., J.D.
Reformed Aerospace Engineer
Remove invalid nonsense for email.

Reed Snellenberger wrote:
All the more reason to provide for establishing supply "depots" in Martian
orbit.

Agreed. But for perishables, sending supplies ahead of time requires that your
food have an every greater "shelf life".

What sort of degree of confidence is there that the crewed vehicle could enter
the same mars orbit as the supply ship and dock/mate/berth with it ?

Is it confident enough that it would wave any requirement for the crewed
vehicle be able to return home if it fails to meet up with the resupply ship ?

Is there any empirical data on the minimal requirements to keep someone alive
for 6 months ? Would there be a significant difference in food/air/water
requirement if one lives a lethargic lifestyle versus normal one ? (for
instance, if resupply fails, could the ship still have sufficient supplies to
keep crew barely alive for a long journey back home).

If you're clever enough, you may even be able to develop a plan for
an in-transit re-supply.

How realistic would such a plan be ? Would it absolutely require a launch
before the crewed vehicle ? Should the crewed vehicle failed to meet with a
resupply ship at Mars and be forced to return to Earth with barly enough
supplies, would there be aby way for earth to send a resupply ship to meet the
returning ship ?

Henry Spencer wrote:

The real trick, however, is recycling wash water and laundry water. Those
are the big water consumers for long trips. There have been some limited
demonstrations of such recycling, but it still needs work.

Two words: "edible underwear".

Pat