"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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