[FPSPACE] Moon architecture outlined
DSFPortree at aol.com
DSFPortree at aol.com
Sun Jul 31 11:50:36 EDT 2005
Well, now that the Sentinel has published this, I'm a little less reluctant
to share info!
First off, the Sentinel has most of it correct, though it's not hard to tell
that it's written by someone who hasn't studied moon & Mars planning for very
long, since it places emphasis on some things that don't seem important and
doesn't follow some interesting leads.
A week or so ago I posted the outline of the lunar achitecture here. This
architecture picks the best features of Apollo and work done since about 1991
(especially 1991-1993 and 1997-present). Recall that the EOR and Direct Ascent
Apollo scenarios differed primarily at the Earth end. The basic lunar mission
spacecraft was the same. This isn't hugely different from the late SEI EOR FLO
scenario in overall philosophy, though less massive and more incremental
overall. FLO was Griffin's baby. Interestingly, it has exactly the same evolutionary
relationship with a Mars mission as FLO did. EOR was selected partly because
it provides Mars ship assembly experience (though I suspect that that's partly
a rationalization - a really big heavy-lifter just wasn't in the cards - too
The SDLV third stage is the EDS stage - that is, it serves the same role as
the Apollo S-IVB. It places the two-stage LSAM lander into phasing orbit. The
CEV docks, then the EDS launches this Apollo-like assemblage toward the moon.
The EDS then separates. The LSAM descent stage places the LSAM/CEV into lunar
orbit. That's rather different from Apollo. In this scenario, the robust
vehicle is not the CSM-equivalent spacecraft, it's the LM-equivalent. That's because
the CEV is designed primarily for Earth-orbital station ops. All that lunar
capacity would be wasted if it had to be flown to ISS every mission regardless
of mission. So, the lunar capability is shunted off to the lunar vehicle.
The LSAM has a lot of nice features as presently designed. For example, an
airlock. Borrowing from Brand Norman Griffin's SEI designs for Boeing, the
lander is horizontally arranged - that puts the hatch near the ground. LM was
vertical. Horizontalness makes unloading cargo from the cargo version relatively
easy - no giant 90-DAY STUDY-type unloader required.
More importantly, it can land anywhere on the moon and return. Apollo had a
lot of limitations as to places it could reach. This capability exists
primarily to get at the lunar poles.
I like to look at these plans to see if there are any single-point failure
opportunities. What's going to make the headlines someday when something goes
wrong? This scenario does contain some - basically the same ones Apollo had. If
ascent propulsion fails, you're stuck. If the rendezvous in lunar orbit fails,
you're stuck. If CEV propulsion fails, you're stuck.
I'm sure some people will be nervous about leaving the CEV unpiloted in lunar
orbit. LSAM is the active vehicle in lunar rendezvous. That's indicative of a
non-Apollo approach with some far-reaching implications. This is *not* Apollo
LOR, though it looks like it from a distance. Some of the advanced Apollo
scenarios planned in the 1960s proposed that approach, but it wasn't much
favored. Still, that the Griffin-led team proposes this should not be surprising,
since the Mars scenarios since 1993 have taken a similar tack. Mars missions
really can't leave one or two people in Mars orbit for months, unless it aims to
turn them into cancerous jellyfish.
The key question that is not addressed remains - why the heck are we doing
this? Why should we be committed enough to this scenario to do it over the long
haul, the short haul, or whatever? I've been talking with "normal" people (not
space buffs) about this scenario since I learned about it, and that's the
recurrent question. Folks think it's cool - especially the young 'uns, which is
encouraging - but they want to know why we want to do it. I hope we see some
sensible justifications soon. Coolness is good enough for me and (possibly) you,
but it ain't enough for most people, particularly with all the "real world"
concerns we face.
That's gonna be a lot tougher than designing yet another lunar mission
Relevant info on my website -
David S. F. Portree
Science writer & historian
dsfportree at aol.com
Flagstaff Arizona USA
Romance to Reality: moon & Mars plans
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