Will Moon Robot Fly?

On Nov 17, 1:01*pm, Jeff Findley wrote:
In article 36094615-a09b-4dbd-91b6-
, says...





On Nov 16, 6:55*am, Jeff Findley wrote:
In article f627f741-abca-40dc-938d-6379b643c483
@fh19g2000vbb.googlegroups.com, says...

That's a little more like it. *The long term storage of HTP and
methane is also not as problematic as the unavoidable boil-off of LH2
and LOx.

I disagree. *Long term storage of LOX and LH2 is a matter of insulation
and perhaps active cooling (if your insulation isn't good enough to keep
the boil off rates as low as you'd like). *LOX isn't that hard, and if
LH2 really is problematic, liquid methane is a good alternative (doesn't
require the extremely low temperatures that LH2 does to keep it liquid). *
That's why NASA was seriously looking into developing a LOX/methane
rocket engine.

Long term storage of HTP is problematic because it decomposes over time
and becomes less concentrated. *HTP is still used in the Soyuz descent
module. *From memory, HTP decomposition is one of the reasons that Soyuz
is limited to an approximately 6 month duration in space. *Depending on
your definition of "long term" such a time limit may or may not be
acceptable. *For a manned Mars mission, that's definately unacceptable.

Insulation takes up volume and adds inert mass. *So, as long as volume
and mass are not issues, then of course LH2 and LOx are each perfectly
doable for at least several months while losing 1% per day could be
calculated into the mission initial payload requirements as no big
deal.

If we can get that boil-off down to 0.1% per day would be nearly
ideal.

Talk to the guys who build and fly Centaur stages about what's possible. *
They know better than anyone, even NASA, about how to build and fly
cryogenic upper stages. *

NASA and Commercial industry combine to outline FTD Propellant Depot
planhttp://www.nasaspaceflight.com/2010/08/nasa-commercial-combine-outline-
ftd-propellant-depot-plan/

Not everyone in NASA was convinced that Ares V was the best way to move
forward.

Jeff
--
42

But those in charge of NASA do not permit rogue individuals or even
deductive reasoning among the team, so it's one for all (period), or
else. In that group/cabal or even DARPA, Mook would last one day
before they had him escorted off the property and his security pass
revoked, whereas mainstream parrots and brown-nosed clowns all get to
stay put.

Boeing OASIS was a perfectly good idea that should have been
implemented as of more than a decade ago. Actually the cool location
of Earth L2 would be even better, perhaps because it's relatively
cool.

~ BG

On Nov 17, 3:05*pm, Brad Guth wrote:
On Nov 16, 6:55*am, Jeff Findley wrote:



In article f627f741-abca-40dc-938d-6379b643c483
@fh19g2000vbb.googlegroups.com, says...

That's a little more like it. *The long term storage of HTP and
methane is also not as problematic as the unavoidable boil-off of LH2
and LOx.

I disagree. *Long term storage of LOX and LH2 is a matter of insulation
and perhaps active cooling (if your insulation isn't good enough to keep
the boil off rates as low as you'd like). *LOX isn't that hard, and if
LH2 really is problematic, liquid methane is a good alternative (doesn't
require the extremely low temperatures that LH2 does to keep it liquid).. *
That's why NASA was seriously looking into developing a LOX/methane
rocket engine.

Long term storage of HTP is problematic because it decomposes over time
and becomes less concentrated. *HTP is still used in the Soyuz descent
module. *From memory, HTP decomposition is one of the reasons that Soyuz
is limited to an approximately 6 month duration in space. *Depending on
your definition of "long term" such a time limit may or may not be
acceptable. *For a manned Mars mission, that's definately unacceptable.

Jeff
--
42

Insulation takes up volume and adds inert mass. *So, as long as volume
and mass are not issues, then of course LH2 and LOx are each perfectly
doable for at least several months while losing 1% per day could be
calculated into the mission initial payload requirements as no big
deal.

1% loss per day cuts the total in half every 69.66 days.

A 730 day mission would need to carry 1,535.75 kg at the outset to
deliver 1 kg the final day.

If we can get that boil-off down to 0.1% per day would be nearly
ideal.

0.1% loss per day cuts the total in half every 696.61 days.

A 730 day mission would need to carry 2.08 kg at the outset to deliver
1 kg the final day.


Having a nuclear powered helium refrigeration system could potentially
eliminate boil-off, so how much volume and how many tonnes would that
involve?

Well 452 kilojoules of energy per kg of hydrogen boil off. A
cryogenic refrigerator must remove this from the hydrogen. Given even
crappy refrigeration efficiency it will take less than 1,200
kilojoules of external energy to pump this much out.

So, with

1% boil off - and 1,000 kg - we've got 10 kg per day
0.1% boil off - and 1,000 kg - we've got 1 kg per day

This means that 4520 kJ per day is leaking into the tank in the first
case and 12 MJ per day is needed then. Dividing by the 86,400 seconds
each day this translates to a cryogenic refrigerator that's 139
kilowatts continuous - per metric ton of hydrogen with this type of
tank.

Power levels drop to 13.9 kilowatts per metric ton of hydrogen with a
more efficient tank.

Now the interesting thing is if the hydrogen is combined with oxygen
in a fuel cell to run the refrigerator a kg of hydrogen releases 143
MJ. This is more than 300 times the power level of the
refrigerator.

So, a fuel cell that used the hydrogen and oxygen itself to power a
cryogenic refrigerator divides the loss rate by 300 - so a 1% boil off
tank becomes a 0.003% boil off tank with this added to it. (you need
oxygen too)

So, this is one way to do it.

SP-100 Massed 5.4 tonnes and produced 0.2 MWe output. This would be
enough to carry 1.4 tonnes of hydrogen in the 1% tanks and 14 tonnes
of hydrogen in the 0.1% tanks indefinitely.

A TPV based system would mass just as much but produce five times as
much electricity for the masses. This increases the propellant that
might be carried to 7.0 tonnes and 70.0 tonnes respectively.

http://docs.google.com/viewer?a=v&q=...ree_Thesis.pdf



*~ BG

On Nov 17, 8:20*pm, Brad Guth wrote:
On Nov 17, 1:01*pm, Jeff Findley wrote:



In article 36094615-a09b-4dbd-91b6-
, says...

On Nov 16, 6:55*am, Jeff Findley wrote:
In article f627f741-abca-40dc-938d-6379b643c483
@fh19g2000vbb.googlegroups.com, says...

That's a little more like it. *The long term storage of HTP and
methane is also not as problematic as the unavoidable boil-off of LH2
and LOx.

I disagree. *Long term storage of LOX and LH2 is a matter of insulation
and perhaps active cooling (if your insulation isn't good enough to keep
the boil off rates as low as you'd like). *LOX isn't that hard, and if
LH2 really is problematic, liquid methane is a good alternative (doesn't
require the extremely low temperatures that LH2 does to keep it liquid). *
That's why NASA was seriously looking into developing a LOX/methane
rocket engine.

Long term storage of HTP is problematic because it decomposes over time
and becomes less concentrated. *HTP is still used in the Soyuz descent
module. *From memory, HTP decomposition is one of the reasons that Soyuz
is limited to an approximately 6 month duration in space. *Depending on
your definition of "long term" such a time limit may or may not be
acceptable. *For a manned Mars mission, that's definately unacceptable.

Insulation takes up volume and adds inert mass. *So, as long as volume
and mass are not issues, then of course LH2 and LOx are each perfectly
doable for at least several months while losing 1% per day could be
calculated into the mission initial payload requirements as no big
deal.

If we can get that boil-off down to 0.1% per day would be nearly
ideal.

Talk to the guys who build and fly Centaur stages about what's possible.. *
They know better than anyone, even NASA, about how to build and fly
cryogenic upper stages. *

NASA and Commercial industry combine to outline FTD Propellant Depot
planhttp://www.nasaspaceflight.com/2010/08/nasa-commercial-combine-outline-
ftd-propellant-depot-plan/

Not everyone in NASA was convinced that Ares V was the best way to move
forward.

Jeff
--
42

But those in charge of NASA do not permit rogue individuals or even
deductive reasoning among the team, so it's one for all (period), or
else. *In that group/cabal or even DARPA, Mook would last one day
before they had him escorted off the property and his security pass
revoked, whereas mainstream parrots and brown-nosed clowns all get to
stay put.

Boeing OASIS was a perfectly good idea that should have been
implemented as of more than a decade ago. *Actually the cool location
of Earth L2 would be even better, perhaps because it's relatively
cool.

*~ BG

Its been my experience people welcome good ideas no matter where they
come from.

On Nov 18, 9:15*am, William Mook wrote:
On Nov 17, 8:20*pm, Brad Guth wrote:



On Nov 17, 1:01*pm, Jeff Findley wrote:

In article 36094615-a09b-4dbd-91b6-
, says....

On Nov 16, 6:55*am, Jeff Findley wrote:
In article f627f741-abca-40dc-938d-6379b643c483
@fh19g2000vbb.googlegroups.com, says...

That's a little more like it. *The long term storage of HTP and
methane is also not as problematic as the unavoidable boil-off of LH2
and LOx.

I disagree. *Long term storage of LOX and LH2 is a matter of insulation
and perhaps active cooling (if your insulation isn't good enough to keep
the boil off rates as low as you'd like). *LOX isn't that hard, and if
LH2 really is problematic, liquid methane is a good alternative (doesn't
require the extremely low temperatures that LH2 does to keep it liquid). *
That's why NASA was seriously looking into developing a LOX/methane
rocket engine.

Long term storage of HTP is problematic because it decomposes over time
and becomes less concentrated. *HTP is still used in the Soyuz descent
module. *From memory, HTP decomposition is one of the reasons that Soyuz
is limited to an approximately 6 month duration in space. *Depending on
your definition of "long term" such a time limit may or may not be
acceptable. *For a manned Mars mission, that's definately unacceptable.

Insulation takes up volume and adds inert mass. *So, as long as volume
and mass are not issues, then of course LH2 and LOx are each perfectly
doable for at least several months while losing 1% per day could be
calculated into the mission initial payload requirements as no big
deal.

If we can get that boil-off down to 0.1% per day would be nearly
ideal.

Talk to the guys who build and fly Centaur stages about what's possible. *
They know better than anyone, even NASA, about how to build and fly
cryogenic upper stages. *

NASA and Commercial industry combine to outline FTD Propellant Depot
planhttp://www.nasaspaceflight.com/2010/08/nasa-commercial-combine-outline-
ftd-propellant-depot-plan/

Not everyone in NASA was convinced that Ares V was the best way to move
forward.

Jeff
--
42

But those in charge of NASA do not permit rogue individuals or even
deductive reasoning among the team, so it's one for all (period), or
else. *In that group/cabal or even DARPA, Mook would last one day
before they had him escorted off the property and his security pass
revoked, whereas mainstream parrots and brown-nosed clowns all get to
stay put.

Boeing OASIS was a perfectly good idea that should have been
implemented as of more than a decade ago. *Actually the cool location
of Earth L2 would be even better, perhaps because it's relatively
cool.

*~ BG

Its been my experience people welcome good ideas no matter where they
come from.

That hasn’t been my experience, nor yours if getting any of your solar
farms and those many positive/constructive associated implications for
the environment and lower energy cost underway is any example, because
you’ve been systematically turned down, banished and/or rejected at
every attempt so far. Are you saying that decade of purely negative
outcome is about to change?

~ BG

On Nov 18, 9:14*am, William Mook wrote:
On Nov 17, 3:05*pm, Brad Guth wrote:



On Nov 16, 6:55*am, Jeff Findley wrote:

In article f627f741-abca-40dc-938d-6379b643c483
@fh19g2000vbb.googlegroups.com, says...

That's a little more like it. *The long term storage of HTP and
methane is also not as problematic as the unavoidable boil-off of LH2
and LOx.

I disagree. *Long term storage of LOX and LH2 is a matter of insulation
and perhaps active cooling (if your insulation isn't good enough to keep
the boil off rates as low as you'd like). *LOX isn't that hard, and if
LH2 really is problematic, liquid methane is a good alternative (doesn't
require the extremely low temperatures that LH2 does to keep it liquid). *
That's why NASA was seriously looking into developing a LOX/methane
rocket engine.

Long term storage of HTP is problematic because it decomposes over time
and becomes less concentrated. *HTP is still used in the Soyuz descent
module. *From memory, HTP decomposition is one of the reasons that Soyuz
is limited to an approximately 6 month duration in space. *Depending on
your definition of "long term" such a time limit may or may not be
acceptable. *For a manned Mars mission, that's definately unacceptable.

Jeff
--
42

Insulation takes up volume and adds inert mass. *So, as long as volume
and mass are not issues, then of course LH2 and LOx are each perfectly
doable for at least several months while losing 1% per day could be
calculated into the mission initial payload requirements as no big
deal.

1% loss per day cuts the total in half every 69.66 days.

A 730 day mission would need to carry 1,535.75 kg at the outset to
deliver 1 kg the final day.

If we can get that boil-off down to 0.1% per day would be nearly
ideal.

0.1% loss per day cuts the total in half every 696.61 days.

A 730 day mission would need to carry 2.08 kg at the outset to deliver
1 kg the final day.

Having a nuclear powered helium refrigeration system could potentially
eliminate boil-off, so how much volume and how many tonnes would that
involve?

Well 452 kilojoules of energy per kg of hydrogen boil off. * A
cryogenic refrigerator must remove this from the hydrogen. *Given even
crappy refrigeration efficiency it will take less than 1,200
kilojoules of external energy to pump this much out.

So, with

* * 1% boil off - and 1,000 kg *- we've got 10 kg per day
* 0.1% boil off - and 1,000 kg - we've got * 1 kg per day

This means that 4520 kJ per day is leaking into the tank in the first
case and 12 MJ per day is needed then. *Dividing by the 86,400 seconds
each day this translates to a cryogenic refrigerator that's 139
kilowatts continuous - per metric ton of hydrogen with this type of
tank.

Power levels drop to 13.9 kilowatts per metric ton of hydrogen with a
more efficient tank.

Now the interesting thing is if the hydrogen is combined with oxygen
in a fuel cell to run the refrigerator a kg of hydrogen releases 143
MJ. * This is more than 300 times the power level of the
refrigerator.

So, a fuel cell that used the hydrogen and oxygen itself to power a
cryogenic refrigerator divides the loss rate by 300 - so a 1% boil off
tank becomes a 0.003% boil off tank with this added to it. *(you need
oxygen too)

So, this is one way to do it.

SP-100 Massed 5.4 tonnes and produced 0.2 MWe output. *This would be
enough to carry 1.4 tonnes of hydrogen in the 1% tanks and 14 tonnes
of hydrogen in the 0.1% tanks indefinitely.

A TPV based system would mass just as much but produce five times as
much electricity for the masses. *This increases the propellant that
might be carried to 7.0 tonnes and 70.0 tonnes respectively.

http://docs.google.com/viewer?a=v&q=...www.projectrho....

*~ BG

I kinda like where this is going. In other words, waste not, want
not.

Using those basic 1%/day boil-off tanks and then helium cryo-
refrigerate them tanks back down to as little as .003%/day, as such
seems like a perfectly good win-win, even if it only achieves a 0.01%/
day isn’t exactly bad.

A 100 tonne payload of LH2 is only going to boil-off at most 10 kg/
day, and your LEO delivery options should have no problems with
getting such amounts of LH2 and LOx plus whatever insulated
containments and their helium refrigeration up there and ready to go
wherever needed. Ideally a Mook fuel depot/gateway or OASIS at Earth
L2 could become your best ever ticket to ride, for providing modules
of 100 tonnes LH2 and 600 tonnes LOx each (leaves lots of LOx for
human consumption and other uses).

However the waste not, want not utilization of 10 kg/day of h2 and 60
kg/day of o2 seems nearly ideal for such an outpost fuel depot that
can be robotically refueled or replenished as often as needed.

Why don’t you do something like this, except include the Earth-moon L1
Mook outpost/gateway (aka Clarke station) with its substantial OASIS
cache of LH2 and LOx parked within that nifty zero delta-V location.
http://www.nss.org/settlement/moon/LANTR.html

Only be sure to make that lunar surface look as nearly dark as coal
and extremely contrasty, instead of using the Apollo ruse albedo
average of 65% and always having shadow fill-in illumination from some
magical illumination source and otherwise always UV inert, because you
and I know better.

~ BG

On Nov 18, 12:14*pm, William Mook wrote:
On Nov 17, 3:05*pm, Brad Guth wrote:



On Nov 16, 6:55*am, Jeff Findley wrote:

In article f627f741-abca-40dc-938d-6379b643c483
@fh19g2000vbb.googlegroups.com, says...

That's a little more like it. *The long term storage of HTP and
methane is also not as problematic as the unavoidable boil-off of LH2
and LOx.

I disagree. *Long term storage of LOX and LH2 is a matter of insulation
and perhaps active cooling (if your insulation isn't good enough to keep
the boil off rates as low as you'd like). *LOX isn't that hard, and if
LH2 really is problematic, liquid methane is a good alternative (doesn't
require the extremely low temperatures that LH2 does to keep it liquid). *
That's why NASA was seriously looking into developing a LOX/methane
rocket engine.

Long term storage of HTP is problematic because it decomposes over time
and becomes less concentrated. *HTP is still used in the Soyuz descent
module. *From memory, HTP decomposition is one of the reasons that Soyuz
is limited to an approximately 6 month duration in space. *Depending on
your definition of "long term" such a time limit may or may not be
acceptable. *For a manned Mars mission, that's definately unacceptable.

Jeff
--
42

Insulation takes up volume and adds inert mass. *So, as long as volume
and mass are not issues, then of course LH2 and LOx are each perfectly
doable for at least several months while losing 1% per day could be
calculated into the mission initial payload requirements as no big
deal.

1% loss per day cuts the total in half every 69.66 days.

A 730 day mission would need to carry 1,535.75 kg at the outset to
deliver 1 kg the final day.

If we can get that boil-off down to 0.1% per day would be nearly
ideal.

0.1% loss per day cuts the total in half every 696.61 days.

A 730 day mission would need to carry 2.08 kg at the outset to deliver
1 kg the final day.

Having a nuclear powered helium refrigeration system could potentially
eliminate boil-off, so how much volume and how many tonnes would that
involve?

Well 452 kilojoules of energy per kg of hydrogen boil off. * A
cryogenic refrigerator must remove this from the hydrogen. *Given even
crappy refrigeration efficiency it will take less than 1,200
kilojoules of external energy to pump this much out.

So, with

* * 1% boil off - and 1,000 kg *- we've got 10 kg per day
* 0.1% boil off - and 1,000 kg - we've got * 1 kg per day

This means that 4520 kJ per day is leaking into the tank in the first
case and 12 MJ per day is needed then. *Dividing by the 86,400 seconds
each day this translates to a cryogenic refrigerator that's 139
kilowatts continuous - per metric ton of hydrogen with this type of
tank.

Power levels drop to 13.9 kilowatts per metric ton of hydrogen with a
more efficient tank.

Now the interesting thing is if the hydrogen is combined with oxygen
in a fuel cell to run the refrigerator a kg of hydrogen releases 143
MJ. * This is more than 300 times the power level of the
refrigerator.

So, a fuel cell that used the hydrogen and oxygen itself to power a
cryogenic refrigerator divides the loss rate by 300 - so a 1% boil off
tank becomes a 0.003% boil off tank with this added to it. *(you need
oxygen too)

So, this is one way to do it.

SP-100 Massed 5.4 tonnes and produced 0.2 MWe output. *This would be
enough to carry 1.4 tonnes of hydrogen in the 1% tanks and 14 tonnes
of hydrogen in the 0.1% tanks indefinitely.

A TPV based system would mass just as much but produce five times as
much electricity for the masses. *This increases the propellant that
might be carried to 7.0 tonnes and 70.0 tonnes respectively.

http://docs.google.com/viewer?a=v&q=...www.projectrho....

*~ BG


*****************
CORRECTION
*****************

I think I may have gotten a few digits wrong...

4,520,000 Joules for 10 kg over 24 hours is 138.9 Watts - not KW.
452,000 Joules for 1 kg over 24 hours is 13.9 Watts - not KW

So, for a 5,400 kg Snap 100 generating 200,0000 Watts we can run a
refrigerator that keeps 1,439 metric tons of hydrogen cool in the
first case and 14,390 tons of hydrogen cool in the second case.
Using high efficiency TPV nuclear power output is 5x higher so the
tonnage is 5x greater - 7,195 metric tons in a 1% per day loss tank or
71,950 tonnes in a 0.1% per day loss tank

2,400,000 Wt 2,400,000 Wt
SP 100 TPV Version
200,000 We 1,000,000 We

5.4 / 1,439 = 0.38% 5.4 / 7,195 = 0.08%
5.4 / 14,390 = 0.038% 5.4 / 7,195 = 0.008%


A solar panel generating 200 Watts at Mars keeps 1.4 tonnes of cool or
14 tonnes cool depending on tank. The same panel at Earth would
generate 500 Watts - and keep 3.5 tonnes cool or 35.0 tonnes. This is
1 sq m of panels at using high efficiency multi-junction cells per
tonne. These mass about 4 kg - again 0.4% the total weight.

On Nov 18, 1:31*pm, William Mook wrote:
On Nov 18, 12:14*pm, William Mook wrote:



On Nov 17, 3:05*pm, Brad Guth wrote:

On Nov 16, 6:55*am, Jeff Findley wrote:

In article f627f741-abca-40dc-938d-6379b643c483
@fh19g2000vbb.googlegroups.com, says...

That's a little more like it. *The long term storage of HTP and
methane is also not as problematic as the unavoidable boil-off of LH2
and LOx.

I disagree. *Long term storage of LOX and LH2 is a matter of insulation
and perhaps active cooling (if your insulation isn't good enough to keep
the boil off rates as low as you'd like). *LOX isn't that hard, and if
LH2 really is problematic, liquid methane is a good alternative (doesn't
require the extremely low temperatures that LH2 does to keep it liquid). *
That's why NASA was seriously looking into developing a LOX/methane
rocket engine.

Long term storage of HTP is problematic because it decomposes over time
and becomes less concentrated. *HTP is still used in the Soyuz descent
module. *From memory, HTP decomposition is one of the reasons that Soyuz
is limited to an approximately 6 month duration in space. *Depending on
your definition of "long term" such a time limit may or may not be
acceptable. *For a manned Mars mission, that's definately unacceptable.

Jeff
--
42

Insulation takes up volume and adds inert mass. *So, as long as volume
and mass are not issues, then of course LH2 and LOx are each perfectly
doable for at least several months while losing 1% per day could be
calculated into the mission initial payload requirements as no big
deal.

1% loss per day cuts the total in half every 69.66 days.

A 730 day mission would need to carry 1,535.75 kg at the outset to
deliver 1 kg the final day.

If we can get that boil-off down to 0.1% per day would be nearly
ideal.

0.1% loss per day cuts the total in half every 696.61 days.

A 730 day mission would need to carry 2.08 kg at the outset to deliver
1 kg the final day.

Having a nuclear powered helium refrigeration system could potentially
eliminate boil-off, so how much volume and how many tonnes would that
involve?

Well 452 kilojoules of energy per kg of hydrogen boil off. * A
cryogenic refrigerator must remove this from the hydrogen. *Given even
crappy refrigeration efficiency it will take less than 1,200
kilojoules of external energy to pump this much out.

So, with

* * 1% boil off - and 1,000 kg *- we've got 10 kg per day
* 0.1% boil off - and 1,000 kg - we've got * 1 kg per day

This means that 4520 kJ per day is leaking into the tank in the first
case and 12 MJ per day is needed then. *Dividing by the 86,400 seconds
each day this translates to a cryogenic refrigerator that's 139
kilowatts continuous - per metric ton of hydrogen with this type of
tank.

Power levels drop to 13.9 kilowatts per metric ton of hydrogen with a
more efficient tank.

Now the interesting thing is if the hydrogen is combined with oxygen
in a fuel cell to run the refrigerator a kg of hydrogen releases 143
MJ. * This is more than 300 times the power level of the
refrigerator.

So, a fuel cell that used the hydrogen and oxygen itself to power a
cryogenic refrigerator divides the loss rate by 300 - so a 1% boil off
tank becomes a 0.003% boil off tank with this added to it. *(you need
oxygen too)

So, this is one way to do it.

SP-100 Massed 5.4 tonnes and produced 0.2 MWe output. *This would be
enough to carry 1.4 tonnes of hydrogen in the 1% tanks and 14 tonnes
of hydrogen in the 0.1% tanks indefinitely.

A TPV based system would mass just as much but produce five times as
much electricity for the masses. *This increases the propellant that
might be carried to 7.0 tonnes and 70.0 tonnes respectively.

http://docs.google.com/viewer?a=v&q=...www.projectrho...

*~ BG

*****************
CORRECTION
*****************

I think I may have gotten a few digits wrong...

* 4,520,000 Joules for 10 kg over 24 hours is 138.9 Watts - not KW.
* * *452,000 Joules for * 1 kg over 24 hours is * 13.9 Watts - not KW

So, for a 5,400 kg Snap 100 generating 200,0000 Watts we can run a
refrigerator that keeps 1,439 metric tons of hydrogen cool in the
first case and 14,390 tons of hydrogen cool in the second case.
Using high efficiency TPV nuclear power output is 5x higher so the
tonnage is 5x greater - 7,195 metric tons in a 1% per day loss tank or
71,950 tonnes in a 0.1% per day loss tank

* * 2,400,000 Wt * * * * * * * * * * * * * * * * * * 2,400,000 Wt
* * *SP 100 * * * * * * * * * * * * * * * * * * * * * * *TPV Version
* * *200,000 We * * * * * * * * * * * * * * * * * * *1,000,000 We

* * *5.4 / 1,439 = 0.38% * * * * * * * * * * * * *5.4 / 7,195 = 0.08%
* * *5.4 / 14,390 = 0.038% * * * * * * * * * * *5.4 / 7,195 = 0.008%

A solar panel generating 200 Watts at Mars keeps 1.4 tonnes of cool or
14 tonnes cool depending on tank. *The same panel at Earth would
generate 500 Watts - and keep 3.5 tonnes cool or 35.0 tonnes. *This is
1 sq m of panels at using high efficiency multi-junction cells per
tonne. *These mass about 4 kg - again 0.4% the total weight.

That still works better than any other option that's on the table.
So, when does Mook start the actual ball rolling?

~ BG

On Nov 18, 1:31*pm, William Mook wrote:
On Nov 18, 12:14*pm, William Mook wrote:



On Nov 17, 3:05*pm, Brad Guth wrote:

On Nov 16, 6:55*am, Jeff Findley wrote:

In article f627f741-abca-40dc-938d-6379b643c483
@fh19g2000vbb.googlegroups.com, says...

That's a little more like it. *The long term storage of HTP and
methane is also not as problematic as the unavoidable boil-off of LH2
and LOx.

I disagree. *Long term storage of LOX and LH2 is a matter of insulation
and perhaps active cooling (if your insulation isn't good enough to keep
the boil off rates as low as you'd like). *LOX isn't that hard, and if
LH2 really is problematic, liquid methane is a good alternative (doesn't
require the extremely low temperatures that LH2 does to keep it liquid). *
That's why NASA was seriously looking into developing a LOX/methane
rocket engine.

Long term storage of HTP is problematic because it decomposes over time
and becomes less concentrated. *HTP is still used in the Soyuz descent
module. *From memory, HTP decomposition is one of the reasons that Soyuz
is limited to an approximately 6 month duration in space. *Depending on
your definition of "long term" such a time limit may or may not be
acceptable. *For a manned Mars mission, that's definately unacceptable.

Jeff
--
42

Insulation takes up volume and adds inert mass. *So, as long as volume
and mass are not issues, then of course LH2 and LOx are each perfectly
doable for at least several months while losing 1% per day could be
calculated into the mission initial payload requirements as no big
deal.

1% loss per day cuts the total in half every 69.66 days.

A 730 day mission would need to carry 1,535.75 kg at the outset to
deliver 1 kg the final day.

If we can get that boil-off down to 0.1% per day would be nearly
ideal.

0.1% loss per day cuts the total in half every 696.61 days.

A 730 day mission would need to carry 2.08 kg at the outset to deliver
1 kg the final day.

Having a nuclear powered helium refrigeration system could potentially
eliminate boil-off, so how much volume and how many tonnes would that
involve?

Well 452 kilojoules of energy per kg of hydrogen boil off. * A
cryogenic refrigerator must remove this from the hydrogen. *Given even
crappy refrigeration efficiency it will take less than 1,200
kilojoules of external energy to pump this much out.

So, with

* * 1% boil off - and 1,000 kg *- we've got 10 kg per day
* 0.1% boil off - and 1,000 kg - we've got * 1 kg per day

This means that 4520 kJ per day is leaking into the tank in the first
case and 12 MJ per day is needed then. *Dividing by the 86,400 seconds
each day this translates to a cryogenic refrigerator that's 139
kilowatts continuous - per metric ton of hydrogen with this type of
tank.

Power levels drop to 13.9 kilowatts per metric ton of hydrogen with a
more efficient tank.

Now the interesting thing is if the hydrogen is combined with oxygen
in a fuel cell to run the refrigerator a kg of hydrogen releases 143
MJ. * This is more than 300 times the power level of the
refrigerator.

So, a fuel cell that used the hydrogen and oxygen itself to power a
cryogenic refrigerator divides the loss rate by 300 - so a 1% boil off
tank becomes a 0.003% boil off tank with this added to it. *(you need
oxygen too)

So, this is one way to do it.

SP-100 Massed 5.4 tonnes and produced 0.2 MWe output. *This would be
enough to carry 1.4 tonnes of hydrogen in the 1% tanks and 14 tonnes
of hydrogen in the 0.1% tanks indefinitely.

A TPV based system would mass just as much but produce five times as
much electricity for the masses. *This increases the propellant that
might be carried to 7.0 tonnes and 70.0 tonnes respectively.

http://docs.google.com/viewer?a=v&q=...www.projectrho...

*~ BG

*****************
CORRECTION
*****************

I think I may have gotten a few digits wrong...

* 4,520,000 Joules for 10 kg over 24 hours is 138.9 Watts - not KW.
* * *452,000 Joules for * 1 kg over 24 hours is * 13.9 Watts - not KW

So, for a 5,400 kg Snap 100 generating 200,0000 Watts we can run a
refrigerator that keeps 1,439 metric tons of hydrogen cool in the
first case and 14,390 tons of hydrogen cool in the second case.
Using high efficiency TPV nuclear power output is 5x higher so the
tonnage is 5x greater - 7,195 metric tons in a 1% per day loss tank or
71,950 tonnes in a 0.1% per day loss tank

* * 2,400,000 Wt * * * * * * * * * * * * * * * * * * 2,400,000 Wt
* * *SP 100 * * * * * * * * * * * * * * * * * * * * * * *TPV Version
* * *200,000 We * * * * * * * * * * * * * * * * * * *1,000,000 We

* * *5.4 / 1,439 = 0.38% * * * * * * * * * * * * *5.4 / 7,195 = 0.08%
* * *5.4 / 14,390 = 0.038% * * * * * * * * * * *5.4 / 7,195 = 0.008%

A solar panel generating 200 Watts at Mars keeps 1.4 tonnes of cool or
14 tonnes cool depending on tank. *The same panel at Earth would
generate 500 Watts - and keep 3.5 tonnes cool or 35.0 tonnes. *This is
1 sq m of panels at using high efficiency multi-junction cells per
tonne. *These mass about 4 kg - again 0.4% the total weight.

14 kwhr per tonne for 24 hours seems entirely doable.

That's certainly better than any other option that's on the table.
So, when does Mook start the actual ball rolling?

~ BG