LSAM

Don't know if this has been discussed before, but I noticed some time ago
that the LSAM will be discarded after it performs its duties. What are some
thoughts on a less wasteful approach:

1) An LSAM that travels between lunar orbit and lunar surface in one piece
(reusable),
2) A CEV that goes from ground-to-earth-orbit-and-back ONLY (crew taxi),
3) An Earth/Moon transfer vehicle that ONLY goes between earth orbit and
lunar orbit (reusable; stationed at ISS),
4) A fuel/cargo/resupply transfer vehicle that takes stuff anywhere.

Maybe this is too complicated, but it seems wasteful to me to throw away one
LSAM for each access to the lunar surface.

Jon

"Jon S. Berndt" wrote in
:

Don't know if this has been discussed before, but I noticed some time
ago that the LSAM will be discarded after it performs its duties. What
are some thoughts on a less wasteful approach:

1) An LSAM that travels between lunar orbit and lunar surface in one
piece (reusable),

Depends on the lunar orbit. Low lunar orbit is not stable enough for
long-term storage due to lunar mascons. It could probably be made to work
if in-space propellant resupply were economical enough. Otherwise, Earth-
Moon L1 is probably better, and can double as a jumping-off point for
planetary missions as well.

2) A CEV that goes from ground-to-earth-orbit-and-back ONLY (crew
taxi),

Could be quite economical, since it could be commercially developed, and
therefore optimized for higher flight rates due to the existence of other
customers.

3) An Earth/Moon transfer vehicle that ONLY goes between earth
orbit and lunar orbit (reusable; stationed at ISS),

There are some tough tradeoffs here. Propulsive braking into LEO is not
practical unless in-space resupply becomes economical. Aerobraking into
LEO requires either high radiation tolerance (multipass aerobraking
involves multiple lengthy passes through the Van Allen belts) and
probably an infeasible amount of shielding if the spacecraft is manned,
or it requires a substantial heatshield for single-pass aerobraking.
Single-pass aerobraking is also tricky because the small scale height of
the Earth's atmosphere (compared to, say, Mars or Titan) tends to magnify
the effects of nav errors. A manned vehicle would probably want an abort-
to-surface option, which involves a full lunar-return heatshield. For the
same reason, single-pass aerobraking into an ISS rendezvous orbit would
also be tricky. It will probably be a non-trivial R&D exercise all on its
own.

4) A fuel/cargo/resupply transfer vehicle that takes stuff anywhere.

Maybe this is too complicated, but it seems wasteful to me to throw
away one LSAM for each access to the lunar surface.

Oh, agreed, but that's likely going to be the answer for any architecture
designed with low flight rates in mind. The trade studies don't favor the
options that require extensive infrastructure (in-space propellant
resupply, L1 stations, etc) until the flight rate gets high enough to
amortize the infrastructure development costs more quickly.


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On Tue, 4 Apr 2006 19:11:09 -0500, in a place far, far away, "Jon S.
Berndt" made the phosphor on my monitor glow in such
a way as to indicate that:

Don't know if this has been discussed before, but I noticed some time ago
that the LSAM will be discarded after it performs its duties. What are some
thoughts on a less wasteful approach:

1) An LSAM that travels between lunar orbit and lunar surface in one piece
(reusable),
2) A CEV that goes from ground-to-earth-orbit-and-back ONLY (crew taxi),
3) An Earth/Moon transfer vehicle that ONLY goes between earth orbit and
lunar orbit (reusable; stationed at ISS),
4) A fuel/cargo/resupply transfer vehicle that takes stuff anywhere.

Most of these things require fuel depots much farther out from LEO
than NASA apparently is willing to contemplate, or implement.

"Jorge R. Frank" wrote in message

"Jon S. Berndt" wrote in

Don't know if this has been discussed before, but I noticed some time
ago that the LSAM will be discarded after it performs its duties. What
are some thoughts on a less wasteful approach:

1) An LSAM that travels between lunar orbit and lunar surface in one
piece (reusable),

Depends on the lunar orbit. Low lunar orbit is not stable enough for
long-term storage due to lunar mascons. It could probably be made to work
if in-space propellant resupply were economical enough. Otherwise, Earth-
Moon L1 is probably better, and can double as a jumping-off point for
planetary missions as well.

I started the train of thought when I contemplated just leaving the LSAM
ascent stage in orbit at the end of a lunar stay. Why crash it into the
surface? Leave it in a "parking" orbit. I thought it might be conceivable
that there could be an extended use for it down the road. The next step from
there is to have some kind of bus that it could attach to ... some kind of
station-keeping device. Maybe with solar panels. The possibilities from that
point a

1) Since there is an ascent stage in lunar orbit, only need to send descent
stage and fuel from earth.
2) There may be some robustness issues for the ascent stage, so don't try to
use it again, but instead keep it attached to the bus (and also any future
ascent stages) as the beginnings of a space station in lunar orbit. It might
simply be an additional place to store stuff, or a possible safe haven. I
can think of a number of potential uses.

The point is, don't intentionally destroy stuff. Sell it. Use it. Whatever.

The related, larger, question I have is, is it better to build a few
vehicles that are single purpose, or a single vehicle for a few purposes?
The latter approach gave us the shuttle.

Jon

"Jon S. Berndt" wrote in
:

"Jorge R. Frank" wrote in message

"Jon S. Berndt" wrote in

Don't know if this has been discussed before, but I noticed some
time ago that the LSAM will be discarded after it performs its
duties. What are some thoughts on a less wasteful approach:

1) An LSAM that travels between lunar orbit and lunar surface in one
piece (reusable),

Depends on the lunar orbit. Low lunar orbit is not stable enough for
long-term storage due to lunar mascons. It could probably be made to
work if in-space propellant resupply were economical enough.
Otherwise, Earth- Moon L1 is probably better, and can double as a
jumping-off point for planetary missions as well.

I started the train of thought when I contemplated just leaving the
LSAM ascent stage in orbit at the end of a lunar stay. Why crash it
into the surface?

The Apollo LM ascent stages were crashed to provide calibration data for
the lunar seismometers. It's a good question whether seismometers will be
part of the new program, and if so how much (if any) calibration they
will require.

Leave it in a "parking" orbit. I thought it might be
conceivable that there could be an extended use for it down the road.
The next step from there is to have some kind of bus that it could
attach to ... some kind of station-keeping device. Maybe with solar
panels. The possibilities from that point a

1) Since there is an ascent stage in lunar orbit, only need to send
descent stage and fuel from earth.
2) There may be some robustness issues for the ascent stage, so don't
try to use it again, but instead keep it attached to the bus (and also
any future ascent stages) as the beginnings of a space station in
lunar orbit. It might simply be an additional place to store stuff, or
a possible safe haven. I can think of a number of potential uses.

The point is, don't intentionally destroy stuff. Sell it. Use it.
Whatever.

I can't agree with that unconditionally. You do have to weigh the costs
both ways. In your scenario, you have the cost of developing the
stationkeeping bus and possibly the costs of making the ascent stage
capable of long-term survival without the descent stage. It's not a
clearcut trade, and the outcome will depend on the flight rate. The
higher the flight rate, the more economical it will be to reuse.

Development funding profile will also be a player. Designing for reuse
will involve more upfront expenditures, and strikes me as one of the
first things that gets dropped when development funding gets tight.

On the flip side, this also strikes me as something that could get added
as an upgrade as the program matures, like the SIM bays and LRVs for the
J-series Apollo missions.

The related, larger, question I have is, is it better to build a few
vehicles that are single purpose, or a single vehicle for a few
purposes? The latter approach gave us the shuttle.

Multipurpose vehicles are not necessarily a bad idea - witness how the
Apollo CSM was able to serve as both a lunar vehicle and as a LEO space
station ferry. The problem with the shuttle is that it attempted to make
the jump to an operational vehicle on the very first iteration, and that
it was shoehorned into too many operational roles.


--
JRF

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check "Organization" (I am not assimilated) and
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Jon S. Berndt wrote:

Don't know if this has been discussed before, but I noticed some time ago
that the LSAM will be discarded after it performs its duties. What are some
thoughts on a less wasteful approach:

Expend, discard and waste, it's the new NASA ESAS mantra!

Get with the program, man! Yer either fer US er agin US!

http://cosmic.lifeform.org

"Jorge R. Frank" wrote in message
I can't agree with that unconditionally. You do have to weigh the costs
both ways. In your scenario, you have the cost of developing the
stationkeeping bus and possibly the costs of making the ascent stage
capable of long-term survival without the descent stage. It's not a
clearcut trade, and the outcome will depend on the flight rate. The
higher the flight rate, the more economical it will be to reuse.

Development funding profile will also be a player. Designing for reuse
will involve more upfront expenditures, and strikes me as one of the
first things that gets dropped when development funding gets tight.

On the flip side, this also strikes me as something that could get added
as an upgrade as the program matures, like the SIM bays and LRVs for the
J-series Apollo missions.

Yes, in a program as "trim" as the current one is trying to be, and with the
costs it would impose, I don't expect what I've described has much appeal.
But, now would be the time to discuss the possibilities. During design,
given several paths to achieve the goal, and where little additional cost is
incurred, choose one that supports reuse - or at least attempt to not
preclude it.

The related, larger, question I have is, is it better to build a few
vehicles that are single purpose, or a single vehicle for a few
purposes? The latter approach gave us the shuttle.

Multipurpose vehicles are not necessarily a bad idea - witness how the
Apollo CSM was able to serve as both a lunar vehicle and as a LEO space
station ferry. The problem with the shuttle is that it attempted to make
the jump to an operational vehicle on the very first iteration, and that
it was shoehorned into too many operational roles.

JRF

I wouldn't call the Apollo CSM a multipurpose vehicle so much as an
extensible vehicle. Same with CEV. IIRC, early concepts for CEV included
access to the lunar surface. That would have been a multipurpose vehicle.

By the way, I meant to mention that a feature of a hypothetical reusable
lunar surface / lunar orbit "shuttle" vehicle that I would also like to see
is that the vehicle is still a two-part vehicle (sort of like LM ascent and
descent stages) where the whole thing goes down and up again, but where the
"ascent stage" is really an "abort" stage, giving an option to return to
orbit if the descent stage fails at any time. I guess this would infer that
the ascent engine would use the same propellant as the descent stage, and
that the tanks would be plumbed to fuel either stage. Costly, and maybe
over-complicated, I know.

Jon

Hey have any spec been written down for the LSAM yet?
I hope one of them is to make the LSAM CO2 scrubbers
compatible/interchangable with the CEVs!


Just my $0.02

Space Cadet

In article , Jon S. Berndt says...

Don't know if this has been discussed before, but I noticed some time ago
that the LSAM will be discarded after it performs its duties. What are some
thoughts on a less wasteful approach:

1) An LSAM that travels between lunar orbit and lunar surface in one piece
(reusable),
2) A CEV that goes from ground-to-earth-orbit-and-back ONLY (crew taxi),
3) An Earth/Moon transfer vehicle that ONLY goes between earth orbit and
lunar orbit (reusable; stationed at ISS),
4) A fuel/cargo/resupply transfer vehicle that takes stuff anywhere.


5) A CEV that also serves as an LSAM. Vertical rocket landing is somewhat
more complex than parachute landing, but it can be made to work and it
works as well on the Moon as it does on Earth.

Extra fuel would of course be required; a CEV that can do the full round
trip on internal tankage would be prohibitively heavy. But if you have
to discard hardware, let it be drop tanks or semi-dumb tankers. Or we
can think about reusing the tankers.

Plus, if the CEV is designed for on-orbit refuelling, it can be launched
with near-empty tanks on an EELV-Medium, maybe even one without solids.


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"Space Cadet" :

Hey have any spec been written down for the LSAM yet?
I hope one of them is to make the LSAM CO2 scrubbers
compatible/interchangable with the CEVs!

If the lesson is well learnt they should try to make as many items as
possible compatible/interchangable in both even if there is a small weight
growth.

Earl Colby Pottinger

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