Re: Is it this easy to live on Mars?

On Sep 28, 12:19 pm, BradGuth <bradg...@xxxxxxxxx> wrote:
On Sep 27, 11:23 pm, Willie.Moo...@xxxxxxxxx wrote:





I note rather than answer a simple question like, where did you get
your 10 kilowatt per person numbrer - you launch into another
senseless diatribe designed to turn an intelligent though uninformed
person against the notion that surviving on Mars is easy by connecting
the idea with highly charged emotionally driven images - a naked orb
as cold as dry ice.   haha - this may all be true, but it changes the
result not at all. Interesting that you post here so much pretending
to be a friend of space travel - and yet you viciously and illogically
attack any reasonable and rational discussion of best practices.
Shame on you Brad.

On Sep 26, 6:13 pm, BradGuth <bradg...@xxxxxxxxx> wrote:

On Sep 26, 11:01 am, Willie.Moo...@xxxxxxxxx wrote:

Why would a person on a mars expedition use as much power as the
entire industrial infrastructure of a citizen in the USA?

Obviously with your expertise and wizardly leadership, a few AA
batteries and you're go to go.

You didn't answer my question, and yet made a highly emotional and
incorrect connection in an attempt to marginalize my quite accurate
analysis.

AA batteries are not primary energy producers.  Solar panels are.  3.3
sq meters of panels (4 x 9 ft) per person is enough to supply all the
energy a person needs on Mars.

A pair of NiCd AA batteries on the other hand contain only 4.1 Wh of
energy when fully charged,   I said it would take about 165 watts
continuous to support someone on Mars.  Each day has 24 hours that's a
total of 3.96 kWh - 966 AA batteries per day - 40 per hour - one every
minute and a half.  On a two year journey you'd need 1,413,106 per
person.  This is over 176 tons of batteries!!!

This is also an under-estimate since the batteries self-discharge at a
rate of 10% per month.  So, over 24 months only 8% of the original
charge would still be present - even in unused batteries.  Which means
6x more batteries are needed for a mission - if one were to be so
foolish as to believe the bull*** you spout.

The last time I'd checked, Mars was a long ways from Earth,

You are an ***.  This is not in dispute and has nothing to do with
the energy it takes to increase the partial pressure of oxygen in the
Martian atmosphere 27,000x using 6 watts of electrical power and a
molecular sieve.

it's
nearly a naked orb

Which means that conduction through the atmosphere is nearly non-
existant - more like the moon as a practical matter, than Antarctica
which means it won't get that cold inside your spacsuit or
spacecraft.  Yet despite the low 0.6 kpa air pressure, despite the
0.13% oxygen concentration, oxygen is EASILY remove from the martian
atmosphere and pressurized using molecular sieve technology to the
same partial pressure it has on Earth.

and for the most part colder than dry ice.

We calculated that the average temperature is slightly warmer than dry
ice.  We also calculated a pressurized dome made of a transparent
sandwich of PET, aerogel, dichroic filter and PET that reflected
infrared light below 1,600 nm wavelength, so that 40% of the incident
radiation was captured inside the dome - like a greenhouse - the
interior temperature within the dome would remain 295K, that's 22 C,
or 72 F.

Forget the lethal radiation factors.

8 millirads per day is not lethal.   Underground radiation is less
than occurs on Earth.

Just park your *** in a serious
walk-in meat freezer that's intentionally displaced with the gas of
CO2,

Lets get the details right shall we?   The seriously big freezer has
inside it a plastic film just described with a 101.3 kpa earht normal
atmosphere. It is surrounded by a CO2 atmosphere that is nearly a
vacuum at 0.6 kpa instead of Earth's 101.3 kpa - the transparent dome
material is irradiated from the outside by 175 Watt sunlamp every
square meter - and in a short period of time, even if everything
starts at -60F it rises to 82F within the bubble.

and stay there for several days, packing along all of your life
sustaining essentials and energy supply as you do your daily physical
labor,

Remember, the atmosphere isn't 100% CO2, only 95% - and like a smoker
on a lung machine - you have a molecular sieve that enhances oxygen
from that thin atmosphere, and another that grabs nitrogen, and water
- powered by a solar panel that uses the sunlamp energy to operate
them.  So, in addition to being warm and having air, and electricity,
you also have water.   This means that all you need are freeze dried
foods - about 1 pound per day - that are then reconstituted with fresh
water drawn from the atmosphere and heated with a simple hot plate.

and be certain to report back.  Don't forget having that meat
locker that's mostly dry-ice frozen as also kept at the near vacuum of
10 mb.

0.6 kilopascals is the proper SI unit.  A real simulator will have
solar power that averages 175 watts per square meter, and 0.13%
oxygen,and larger percentages of nitrogen and water vapor. All of
these trace gases are easily compressed - the energy to do so is given
by;

     W = n RT * ln(Pa/Pb)

Where W = energy
            n = number of moles
            R = rydberg constant 8.314
             T = temp in kelvins (220K)
            Pa = ending pressure (21.2 kpa for oxygen)
            Pb = starting pressure (0.00078 kpa for oxygen

do the calculation and you get an average of 6 watts per person.
Water and nitrogen take another 3 watts.  All other energy needs add
another 156 watts per person. This is supplied by 3.3 sq meters (4 x 9
ft) panel at 40% efficiency from the ambient sunlight.  Energy storage
is provided by a regenerative fuel cell that masses less than 15 lbs
per person.  NOT 965 AA batteries that mass over 240 lbs per person.

What's the all-inclusive energy draw per hour, per day and per week
while sustaining your body mass?

Well, you consume about 1 lb per day of freeze dried foods -
everything else is extracted from the Martian environment using solar
power.  I have computed the compression energy five times already -
its 6 watts for oxygen - and 3 watts for nitrogen and water - and I
expect 156 watts is sufficient given the advances made in electronics
since Apollo and the use rates the Apollo astronauts required to
survive on the surface of the moon.

Oops!  but what if you are dead within day one?

Why would that happen?   Obviously it would not.

 ~ BG

Your wishful 165 or 156 watts of auxiliary energy expended per human
on Mars

is based on actual data taken from the Apollo expeditions which I
provided earlier and repeat here;.

With 11.8 kWh on the ascent stage and 12.4 kWh on the descent stage a
total of 24.2 kWh of electrical energy is available to the
spacecraft.

The Apollo 17 stayed 75 hours on the lunar surface, and spent 3 hours
in free flight - half during ascent,half during landing - a total of
78 hours.on batteries. Assuming no surplus and full discharge -
that's 310 watts for a crew of two. that's 155 watts per person.
Actual discharge rates show that 20% residual power remained in the
spacecraft following the mission which makes actual usage 125 watts
per person - WHICH WAS THE DESIGN GOAL OF THE SPACECRAFT

With today's CMOS technology and improved electornics, power levels
even lower than this are possible. Obviously I am being very
conservative in taking the higher figure as the figure to use for
planning Mars missions.

tells us that your bipolar medication needs to get adjusted.

Non-sequitor given that ACTUAL DATA ON RECORD FOR LUNAR SURFACE
OPERATIONS! lol. Your continuing ignorance of facts provided to you
time after time after time - speak more of your capacities than mine!
haha..

The last time I'd checked, the tropical equator of Mars gets summarily
frozen to dry ice death at night, and doesn't hardly thaw out by day
enough to allow easy digging in that frozen tundra.

The moon and open space vary in temperature even more wildly than
this, yet we operate there with ease given modern spacesuit and
spacecraft technology. In the vacuum of space, despite the bone
chilling cold of space in the shadows, dumping heat overboard the
sealed container is the problem

Each person generates heat energy. Basal Metabolic Rate is related
to Lean Body Mass by

BMR = 340 + (21.8 * LBM)

And for a person with a 50 kg (110 lb) lean body mass - there is 1440
kcal/day - or 69.6 watts of heat do dump overboard..

With a 28% fat content - total body weight is 69.4 kg (152.7 lbs)

Any work increases this output.

The surface area of a human body is 1.8 sq m on average. The Stephan
Boltzman law says that a blackbody radiator ratdiating 69.6 watts
across 1.8 sq m requires a surface temperature of;

W/m2 = 5.67e-8 * T^4
(69.6 / 1.8 / 5.67e-8)^(1/4) = 161.6K

Which implies that an emissivity of 9% - which is equivalent to a thin
*** of mylar - is suffiicent to maintain 295K - which is 22 C or 72
F -optimal temperature for the human body.

Now, imagine a sphere 2.52 meters in diameter with a surface area of
20 sq m. It has a projected area of 5 sq meters which intercepts an
average of 175 W/m2 on the Mars surface and 700 W/m2 in space near
Mars. In addition to 69.6 watts of metabolic heat, there is 165 watts
of electrically generated heat to get rid of, so we have;

On surface

875 W solar
165 W internal
70 W metabolic

1,110 W total heat
20 m2
55 W/m2 -

T = (55 / 5.67e-8)^(1/4) = 176.4K

Which means a thermal emissivity of 12.8% is required to maintain 72F
cabin temp with all systems running.

In space at mars

3,500 solar
165 internal
70 metabolic

3,735 total heat to dump
20 m2
187 W/m2

T = (187 / 5.67e-8)^(1/4) = 239.6K

Which requires emissivity to increase to 43.5% to maintain 72F cabin
temp.

This ability to change the relative emissivity of the cabin is
important since at night we would desire to blanket the sphere in a
high thermal impedance shell, and then thin that shell as the day
progressed. A simple series of layered films that collapsed into a
tiny arc along a half circle along the equator - would provide this
sort of changing capacity around a pressure vessel.

http://farm3.static.flickr.com/2116/2070399043_947bbcd0c8_m.jpg

Other possibilities for temperature control also exist. This simple
calculation shows how easily temperature can be controlled in a
vacuum. Temperature is easily controlled in the near vacuum of the
Martian surface (0.6 kpa - 5.92 millibars)

Just the required energy for digging your own grave is not exactly
insignificant, much less fun looking forward to.

Another nonsequitor because you have yet to establish your point.

I'm sticking with my all-inclusive 5 kw.h demand per individual

Which is obviously and demonstrably wrong.

within
my well shielded

You are obviously confused about long term habitation and exploration
crews.

Sheilding is an important safety factor for explorers and a long term
health concern for settlers- yet radiation is nowhere near the levels
your assert without cause,- and the mission survivable - especially
among older individuals in the 40 to 60 year range.

(mostly underground) camp, and I'd bet my group of
brave souls are going to be a whole lot happier campers than those of
yours unshielded and sucking frozen eggs at their pathetic energy
budget limitation of 165 watts.

Utter rot. The 165 watts is well founded in actual experience with
Apollo's lunar module on the moon's surface using 1960s era
electronics. Today's electronics and techniques mean that this power
level is conservative..

While higher power levels are certainly required to carry out any
industrial activity - such as the production of massive quantities of
rocket fuel for return to Earth - 165 watts generated from solar
sources - is sufficient to provide all the air water and power needs
of each individual.

http://lsda.jsc.nasa.gov/books/apollo/s3ch6.htm

Apollo's experience shows that 3 men consumed on average 181.3 kg of
water over a 9 day period. That's 6.7 liters per person per day.
Oxygen consumption is 0.91 kg per day per person - and I've already
discussed the energy requirements to extract these from the Martian
atmosphere.

165 watts per person at 86% conversion efficiency of a fuel cell -
requires 115 grams of hydrogen be combined 927 grams of oxygen to form
1.02 liter of water per person per day.

On a Mars journey, extracting water from the cabiin with a molecular
sieve and letting the water in waste be dumped overboard after vacuum
dessication and repressurization of the water, reduces net water
consumption to 1.7 liter per day, recycling 5 liters recycled in this
way. This 1 kg of water is provided from the operation of a fuel cell
on board using stored hydrogen and oxygen.

Solar cells may be deployed to assist in this recycling and testing of
the system to be used on the surface of Mars.

Stored Water 0.7 kg per day
2 H2 / O2 1.0 kg per day (165 watts)
dried food 0.9 kg per day
Oxygen 0.9 kg per day

TOTAL 3.5 kg/day

Assuming a 8.4 month journey to Mars, a 7.2 month stay on Mars, and an
8.4 month journey home - brings us back in 2 years exactly. That's
255 days each way and 219 days on the surface..

This means that each crew member consumes 892.5 kg of consumables
during transit.

With water and oxygen extracted from the Martian atmosphere while on
Mars consumption falls to 0.9 kg per day of freeze dried food. So,
that requries an additional 197.1 kg of food per person for the stay
on Mars. An additional 229.5 kg of food is kept for the journey back
to Earth. An additional 178.1 kg of water and 229.5 kg of oxygen are
extracted on Mars per person to recharge the stores for the journey
home.

I have computed that the power level required to supply oxygen,
nitrogen and water for each crew person is no more than 10 wattts. To
recharge oxygen and water stores while on Mars requires no more than
25 watts total of the 165 watt budget over the 219 days on the Mars
surface..

A crew of 30 requires 39.6 tonnes of consumables to be carried along
for a trip to Mars. A 60 ton vessel carrying 475 tonnes of
propellant and 20 tonnes of equipment,lands on Mars, and return to
Earth. Landing the vehicle empty of propellant,means it can be used
as the final stage of a booster leaving Earth for Mars and carry extra
stores to be left on Mars..

Also the ullage, of hydrogen and oxygen in the nearly empty (5 tonnes)
tank may be compressed and used as surplus. The tank itself may be
used as a habitat in transit - and inflatable structures as described
earlier used on the Mars surface. This was all worked out in detail
and was the basis of Skylab which modified a hydrogen tank on an SIVB
for habitation.A hydrogen tank containing 79.2 metric tons of liquid
occupies 1,131 cubic meters.

Cylinder area is minimum when height equals diameter. So, a cylinder
is 11.3 meters in diameter and 11.3 meters tall. With a deck height
2.26 meters, a total of 5 floors - of 100 sq meters each. That's 500
sq meters of deck space. Divided among 30 crew members that's 16.6 sq
meters each (179.4 sq ft) This is larger than the cabin space aboard
a modern nuclear submarine.

Since only 3.88 km/sec is needed to escape Earth, and 6.4 km/sec is
needed for teh return journey, less propellant is needed on the
outbound journey from Earth than leaving Mars. That is, the total
vehicle mass leaving mars is 625 tonnes, with 475 tonnes of propellant
and 150 tonnes vehicle and payload. Leaving Earth with the same 150
tonnes requires only 205 tonnes of propellant. This means an extra
46 tonnes of equipment may be transported and left on Mars - with a
500 tonne stage weight at Earth launch.

The spare 46 tonnes is sufficient to carry along inflatable structures
and equipment to charge it with earth normal air and supply the water
and fuels required.

475 tonnes of propellant retrieved in 219 days is 2.17 metric ton per
day. Since hydrogen oxygen ratio on this rocket is 6 to 1 - this
means that 79.2 metric tons of hydrogen are required, which 361.5 kg
of hydrogen per day. This propellant is derived from 3.25 metric tons
of water per day - extracted from the Martian atmosphere - and
electrolytically reduced and stored aboard the stage. This requires
704 kW of electrical power. This requires 10,100 sq meters of solar
collectors - massing 15 metric tons - and left on the Mars
surface.along with a 30 acre pressurized dome.

While this is 23 kW per person - it is not used to support the crew -
it is used to produce rocket fuel from water. The demand fo each
crew member is less than 165 watts.

Even while this large a power supply isn't needed,if the propellant is
carried along - this amount of power allows the production of rocket
fuel ON the martian surface FROM the atmosphere. There is 723 kg of
excess oxgyen that is also produced by this process - since the
stoichiometric ratio is 8:1 and the rocket uses a fuel to oxygen ratio
of 6:1. this si 24.1 kg of extra oxygen per day per person. 24 x
that needed for breathing. - this may be stored, or used in other
industrial proesses, or used to buffer a large volume of gas for use
in inflatable structures. . .

with 2.7% nitrogen and 0.6 kpa worst cas to raise this to 78% nitrogen
at 101.3 kpa we requires 5,725x pressure - requires 630 watts
continuous to match the oxygen production at a 78%- 21% rate.
Creating 114 kg of air per day - 95 cubic meters. at 1 atmosphere.
Cutting pressure in half and cutting nitrogen to 1/4 its Earth level -
increases volume to over 200 cubic meters per day - so over 219 days
43,800 cubic meters may be blown into a pressure dome.

with 0.03% water and 0.6 kpa worst case, we raise it to 1% of the air
at 101.3 kpa - and that's 52.7x pressure - and is very little power
compared to the rocket fuel operaation.

Using 5% of the output of the rocket operation to pressurize a dome,
provides abundant water, and buffer air, along with a reserve of
liquid nitrogen and oxygen stored in thin film 'tanks' buried in
trenches on Mars - within 60 days - and the dome is occupied in 90
days - providing the crew with very large habitable areas very quickly
- after landing and during the beginning of the refill process.


My group

????

is also going to be highly interactive and otherwise
productive,

You are being an *** again. I am separating the reqiurements of
maintaining a crew member during the journey and on the mars surface
from any industrial processes you might wisht to carry out.

It is quite possible to carry a large solar power statoin to Mars
surface and use it to produce rocket fuel and power a small town. Of
course carrying the propellant with you, and reducing the payloads and
crew sizes - reduces energy requirements. A crew of 16 - on board the
same ship, without any recharging of the supplies or propellants -
reduces total energy needs to less than 2.7 kW total!

as well as accumulating sufficient rocket fuel for
eventually returning home,

Then your estimate of 10 kW per person is an under-estimate

whereas yours are going to be in a bad way

Nonsense.

for banked bone marrow and stem cells, plus in need of prosthetics due
to multiple limb amputations from frostbite and starvation along with
having not accumulated a fluid or solid drop or much less a kg worth
of spare rocket fuel.

Nonsense. If you carry the rocket fuel with you, you don't need to
make it. If you make your rocket fuel on site, you need the energy to
do that - which is separate from what your crew uses. Its a function
of solar panel specific mass and rocket specific impulse.and
structural fraction.

I think your energy budget and likely one-way ticket is going to make
recruiting brave enough souls a wee bit difficult.

I realize you think that, but you have no basis fo rthinking that. If
you bring enough propellant along to return crew - and merely recharge
water and air- a 500 tonne stage can take 16 people and they will use
less than 2.7 kW total -

If you wish to recharge the propellant supply with 15 metric tons of
solar panels, and cary an additional 31 tonnes of engineered films and
inflatable structures, and such, you can with the same 500 tonnes - at
LEO - dispatch 30 people to Mars and build a 750 kW solar panel array
and a small town of 30 acres with underground homes and what not.
This is 25 kW per person - more than double your figure.

Why are my figures so wildly different than yours? BECAUSE YOU PULL
YOURS OUT OF YOUR ASS!

 ~ Brad Guth Brad_Guth Brad.Guth BradGuth BG- Hide quoted text -

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