[FPSPACE] Moon architecture outlined

[DSFPortree at aol.com]

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 
bad).

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 
scenario!

Relevant info on my website -

http://www.marsinstitute.info/rd/faculty/dportree/rtr/ft34.html
http://www.marsinstitute.info/rd/faculty/dportree/rtr/ft38.html
http://www.marsinstitute.info/rd/faculty/dportree/rtr/ma24.html

David

David S. F. Portree
Science writer & historian
dsfportree at aol.com
Flagstaff Arizona USA

DSFP homepage
http://members.aol.com/dsfportree/dsfp.htm

Romance to Reality: moon & Mars plans
http://rtr.marsinstitute.info