Orbital fuel depot

On Friday, April 11, 2014 12:58:22 PM UTC-7, Alain Fournier wrote:
I know we have already talked about orbital fuel depots and I don't

think that just a plain vanilla fuel depot is useful. But I don't

remember seeing anyone puting the following twist to it.



Let's assume we have an orbital fuel depot for LOX and LH2, what can we

do to make it more useful. We can add solar cells and compressors. The

compressors are there to keep the LH2 liquid, the solar cells both power

the compressors and make shade to tanks. Then we can add lots of more

solar cells and an electrolysis plant. So now we don't need to bring LOX

and LH2 to the depot, just water, let the electrolysis plant and the

compressors transform that into LOX and LH2.



Transporting 1 tonne of water to orbit is much easier than transporting

111 kg of H2 plus 889 kg of O2, because the tonne of water uses less

than half the volume and you don't need all the insulation and pressure

valves. Also you don't have to deal with ice buildup. At this point

there is an advantage to using the fuel depot over just carrying your

own fuel with you. Whether it's worth the trouble of building the

infrastructure is another question, but once the infrastructure is

there, it is useful.



Now let's assume that we have this fuel station in LEO that can

transform water to fuel. Someone is going to organise a mission to tow

in a small comet to this station, at this point LEO fuel can become much

cheaper.


So what do you people think of that?

Alain Fournier

NASA/JSC - Boeing OASIS (as well as what others had to offer)
L1 Gateway Report - NASA - NASA's History Office
http://history.nasa.gov/DPT/Architec...T%20Oct_01.pdf

http://web.mit.edu/spacearchitects/A..._IAF_Paper.pdf

In article ,
says...

I know we have already talked about orbital fuel depots and I don't
think that just a plain vanilla fuel depot is useful. But I don't
remember seeing anyone puting the following twist to it.

Let's assume we have an orbital fuel depot for LOX and LH2, what can we
do to make it more useful. We can add solar cells and compressors. The
compressors are there to keep the LH2 liquid, the solar cells both power
the compressors and make shade to tanks. Then we can add lots of more
solar cells and an electrolysis plant. So now we don't need to bring LOX
and LH2 to the depot, just water, let the electrolysis plant and the
compressors transform that into LOX and LH2.

Transporting 1 tonne of water to orbit is much easier than transporting
111 kg of H2 plus 889 kg of O2, because the tonne of water uses less
than half the volume and you don't need all the insulation and pressure
valves. Also you don't have to deal with ice buildup. At this point
there is an advantage to using the fuel depot over just carrying your
own fuel with you. Whether it's worth the trouble of building the
infrastructure is another question, but once the infrastructure is
there, it is useful.

Now let's assume that we have this fuel station in LEO that can
transform water to fuel. Someone is going to organise a mission to tow
in a small comet to this station, at this point LEO fuel can become much
cheaper.

So what do you people think of that?

You're putting all of the complexity in orbit, so I don't think the
numbers will work out very well. The power requirements for
electrolysis is high and on top of that, you want to then refrigerate
the resultant gaseous O2 and H2 into LOX and LH2 which will require more
power and heavy refrigeration equipment.

The worst of your problems is that if you make the thing solar powered,
you need *a lot* of solar panels, which means drag if the thing is in
LEO, which means you'll spend more fuel on keeping the thing in orbit
compared to a "basic" depot which just has to keep LOX and LH2 liquid.

It's actually much easier to make LOX from air and LH2 from other
hydrocarbons petroleum (or natural gas) on the ground and launch it as
LOX and LH2. Your "tanker" to the fuel depot needs fairly decent
insulation, but it doesn't have to be perfect. Your depot can then be
"minimal" in terms of solar panels, refrigeration equipment, orbital re-
boost, and etc. In fact, using the boil-off of gaseous O2 and H2 to run
a rocket engine for orbital re-boost can be a "feature" of non-perfect
insulation and refrigeration since you'll need that anyway.

Jeff
--
"the perennial claim that hypersonic airbreathing propulsion would
magically make space launch cheaper is nonsense -- LOX is much cheaper
than advanced airbreathing engines, and so are the tanks to put it in
and the extra thrust to carry it." - Henry Spencer

In article ,
says...

On 4/11/2014 3:58 PM, Alain Fournier wrote:
Let's assume we have an orbital fuel depot for LOX and LH2

With the death of the USA space shuttle program, we lost an opportunity
to orbit some very large & potentially useful fuel tanks rather than
simply discarding them into the ocean. I do remember reading about
various paper proposals to do just that.

Now this post is just b.s. We still have Atlas, Delta, and Delta Heavy
available. You don't need launches bigger than that for a first cut at
a fuel depot. ULA has studied this and proposed flying prototypes on
existing EELV's. In fact, the space shuttle's payload bay dimensions
are constraining compared to the largest of EELV fairings. For LH2
tanks, larger tanks are obviously desired due to its low density. This
is where the space shuttle would have had a distinct *disadvantage*.

According to Wikipedia, Atlas fairing sizes of 5.4 meters diameter are
standard and sizes as large as 7.2 m in diameter and up to 32.3 m in
length have been considered. Also, Delta Heavy has a 5 meter diameter
payload fairing as a "standard" configuration. By comparison, The
shuttle payload bay is only 18.3 m long and 4.6 m in diameter and simply
could not be made bigger.

Jeff
--
"the perennial claim that hypersonic airbreathing propulsion would
magically make space launch cheaper is nonsense -- LOX is much cheaper
than advanced airbreathing engines, and so are the tanks to put it in
and the extra thrust to carry it." - Henry Spencer

On Sunday, April 13, 2014 7:09:33 AM UTC-7, Jeff Findley wrote:
In article ,

says...



I know we have already talked about orbital fuel depots and I don't

think that just a plain vanilla fuel depot is useful. But I don't

remember seeing anyone puting the following twist to it.



Let's assume we have an orbital fuel depot for LOX and LH2, what can we

do to make it more useful. We can add solar cells and compressors. The

compressors are there to keep the LH2 liquid, the solar cells both power

the compressors and make shade to tanks. Then we can add lots of more

solar cells and an electrolysis plant. So now we don't need to bring LOX

and LH2 to the depot, just water, let the electrolysis plant and the

compressors transform that into LOX and LH2.



Transporting 1 tonne of water to orbit is much easier than transporting

111 kg of H2 plus 889 kg of O2, because the tonne of water uses less

than half the volume and you don't need all the insulation and pressure

valves. Also you don't have to deal with ice buildup. At this point

there is an advantage to using the fuel depot over just carrying your

own fuel with you. Whether it's worth the trouble of building the

infrastructure is another question, but once the infrastructure is

there, it is useful.



Now let's assume that we have this fuel station in LEO that can

transform water to fuel. Someone is going to organise a mission to tow

in a small comet to this station, at this point LEO fuel can become much

cheaper.



So what do you people think of that?



You're putting all of the complexity in orbit, so I don't think the

numbers will work out very well. The power requirements for

electrolysis is high and on top of that, you want to then refrigerate

the resultant gaseous O2 and H2 into LOX and LH2 which will require more

power and heavy refrigeration equipment.



The worst of your problems is that if you make the thing solar powered,

you need *a lot* of solar panels, which means drag if the thing is in

LEO, which means you'll spend more fuel on keeping the thing in orbit

compared to a "basic" depot which just has to keep LOX and LH2 liquid.



It's actually much easier to make LOX from air and LH2 from other

hydrocarbons petroleum (or natural gas) on the ground and launch it as

LOX and LH2. Your "tanker" to the fuel depot needs fairly decent

insulation, but it doesn't have to be perfect. Your depot can then be

"minimal" in terms of solar panels, refrigeration equipment, orbital re-

boost, and etc. In fact, using the boil-off of gaseous O2 and H2 to run

a rocket engine for orbital re-boost can be a "feature" of non-perfect

insulation and refrigeration since you'll need that anyway.



Jeff

--

"the perennial claim that hypersonic airbreathing propulsion would

magically make space launch cheaper is nonsense -- LOX is much cheaper

than advanced airbreathing engines, and so are the tanks to put it in

and the extra thrust to carry it." - Henry Spencer

The Earth-moon L1 depot/gateway/oasis would work, even though it's hot 97+% of the time, plus extra IR heated whenever the nearside of our moon gets illuminated.

Artificial shading could make this location manageable, not to mention terrific solar plus moon IR energy collection and transfer worthy.

On 4/13/2014 10:09 AM, Jeff Findley wrote:
In article ,
says...

I know we have already talked about orbital fuel depots and I don't
think that just a plain vanilla fuel depot is useful. But I don't
remember seeing anyone puting the following twist to it.

....

So what do you people think of that?

You're putting all of the complexity in orbit, so I don't think the
numbers will work out very well. The power requirements for
electrolysis is high and on top of that, you want to then refrigerate
the resultant gaseous O2 and H2 into LOX and LH2 which will require more
power and heavy refrigeration equipment.

The worst of your problems is that if you make the thing solar powered,
you need *a lot* of solar panels, which means drag if the thing is in
LEO, which means you'll spend more fuel on keeping the thing in orbit
compared to a "basic" depot which just has to keep LOX and LH2 liquid.

Hi Jeff,

Yes I completely forgot about the compressors/refrigeration needed for
LOX/LH2. I suspect that the power requirement for that is actually MORE
than what is needed for electrolysis. After all when I was a youngster I
was electrolyzing sodium hydroxide at home with my chemistry set and a
6V battery. But there was no way I was able to compress and cool the
boil off gases to LOX and LH2 with that simple setup!

I'd put the solar panels in GEO and beam the power back to the fuel
depot using lasers. If we pick the right frequency of light such that
Earth's atmosphere would scatter it all over heck and back, then we
don't have to worry about the peace-nik crowd thinking we're building
the ultimate weapon out in GEO. Of course now we've surely doubled the
cost (at least).

It's actually much easier to make LOX from air and LH2 from other
hydrocarbons petroleum (or natural gas) on the ground and launch it as
LOX and LH2. Your "tanker" to the fuel depot needs fairly decent
insulation, but it doesn't have to be perfect. Your depot can then be
"minimal" in terms of solar panels, refrigeration equipment, orbital re-
boost, and etc. In fact, using the boil-off of gaseous O2 and H2 to run
a rocket engine for orbital re-boost can be a "feature" of non-perfect
insulation and refrigeration since you'll need that anyway.


You'd be able to do that if you were making LOX/LH2 locally too.
But I think your first points here are persuasive. At least to get it
started. I agree it makes more sense to do the separation on the ground
at least for early versions of the fuel depot. If we can get cheap power
from GEO SPS tho, then the water option might be more viable.

Water could also be hauled there from the Moon someday, perhaps even
more cheaply that from the Earth. But that's not a starting point. Your
idea is probably the best starting point.

Hmm. Thinking along those lines, maybe this would be a good role for the
SLS instead of this Orion/asteroid nonsense? If you could orbit the main
booster stretched w/o an upper stage, using the highly efficient SSME
derivatives maybe there would be enough fuel left over to stock a depot?
Or maybe the rocket core IS the fuel depot? You'd need to make the ME's
restartable for station-keeping.

Jeff


Dave

On 4/13/2014 10:20 AM, Jeff Findley wrote:
In article ,
says...

On 4/11/2014 3:58 PM, Alain Fournier wrote:
Let's assume we have an orbital fuel depot for LOX and LH2

With the death of the USA space shuttle program, we lost an opportunity
to orbit some very large & potentially useful fuel tanks rather than
simply discarding them into the ocean. I do remember reading about
various paper proposals to do just that.

Now this post is just b.s.
How can you know if it's BS, since you clearly don't even understand
what I was talking about?

We still have Atlas, Delta, and Delta Heavy
available.

True.

By comparison, The
shuttle payload bay is only 18.3 m long and 4.6 m in diameter and simply
could not be made bigger.

Which is exactly why the shuttle had a huge EXTERNAL fuel tank. For
carrying heavy loads to orbit, it made sense to drop those tanks as soon
as possible. However, it was always possible to carry them all the way
to orbit and use them for various purposes. If we wanted to build an
orbital fuel depot, a couple of those tanks would have been a great start.

On 4/13/2014 6:25 PM, Vaughn wrote:

Which is exactly why the shuttle had a huge EXTERNAL fuel tank. For
carrying heavy loads to orbit, it made sense to drop those tanks as soon
as possible. However, it was always possible to carry them all the way
to orbit and use them for various purposes. If we wanted to build an
orbital fuel depot, a couple of those tanks would have been a great start.


Vaughn,

We no longer have Shuttle or Shuttle ET. But we *may* someday have a big
LH2/LOX core SLS rocket. Would that not suffice?

Dave

On 4/13/2014 6:38 PM, David Spain wrote:
On 4/13/2014 6:25 PM, Vaughn wrote:

Which is exactly why the shuttle had a huge EXTERNAL fuel tank. For
carrying heavy loads to orbit, it made sense to drop those tanks as soon
as possible. However, it was always possible to carry them all the way
to orbit and use them for various purposes. If we wanted to build an
orbital fuel depot, a couple of those tanks would have been a great
start.


Vaughn,

We no longer have Shuttle

Thanks, but I knew that.

or Shuttle ET.

Well yes we do. The Shuttle program had at least one example left over.
But we obviously have no capacity to orbit one now.

But we *may* someday have a big
LH2/LOX core SLS rocket. Would that not suffice?

I'm no expert on the SLS. Would it have the capacity to put it's own
first stage fuel tanks into orbit like the Space Shuttle reportedly could?

But yes. An SLS, like several other rockets that we already have in
inventory, could certainly be configured to orbit some sort of a tank as
its payload.

On 13/04/2014 12:26 AM, wrote:
On April 11 2014 19:34:44 UTC-4, Wrong Stuff wrote :
I like the idea as it could be a component of a mobile industrial
base.

Processing water from say the moon (if it has enough) and then as
things unfold move the unit/module/processing base close to an icy
asteroid.

I had in mind moving the icy asteroid or comet to LEO, or at least a
big chunk of ice from it, rather than the eloctrolysing and
liquifying plant to the asteroid. There are pros and cons both ways.

Not a comet, I think. The delta-V required would defeat the purpose.

A NEO icy asteroid is a nicer idea - except are there any? Any water in
NEO would surely have evaporated long ago.

That leaves objects in orbits far enough out for ice to have survived.
Moving them into Earth orbit is a big task.

Sylvia.

In article ,
says...
The Earth-moon L1 depot/gateway/oasis would work, even though
it's hot 97+% of the time, plus extra IR heated whenever the
nearside of our moon gets illuminated.

Artificial shading could make this location manageable, not to
mention terrific solar plus moon IR energy collection and
transfer worthy.

That location may be close to ideal for a fuel depot, but we're talking
about a depot which is delivered water and converts it into LH2 and LOX.
This location reduces the fuel needed for station keeping (with careful
management of its position to balance light pressure on the solar arrays
and the other forces). But, this does not reduce the need for
electrolysis and heavy refrigeration equipment.

I could see a depot like this working for L1 if if the water comes from
the moon rather than earth and you've got no choice but to convert water
to LH2 and LOX. Otherwise, you're putting a lot of expensive equipment
with moving parts in place that will need to be maintained. The record
for this maintaining this sort of equipment on the Salyuts, Mir, and ISS
isn't very good so far.

Jeff
--
"the perennial claim that hypersonic airbreathing propulsion would
magically make space launch cheaper is nonsense -- LOX is much cheaper
than advanced airbreathing engines, and so are the tanks to put it in
and the extra thrust to carry it." - Henry Spencer