Where to put the lander? | Mission Planning Workgroup | Forum

I think that the biggest question mark over our current mission plan, and the one that is going to most hold back the Project Overview document until we fix it, is where we're going to put the lander during the trip to the moon.

The two options are: in an open/openable hanger behind the CM but infront of the PM, and docked to the nose of the CM.

I think we should focus on trying to resolve this soonish.  Issues to consider (green in favour of nose, red in favour of hanger):

• If the LL is docked to the CM nose, it is in the open during the trip, which means it needs to be more radiation/micrometeoroid resistant by itself than it would be if it were in a hanger, where it could be at least partially enclosed for the trip (perhaps fully enclosed if we had covering panels that could be ejected, like those that covered the Apollo LM during launch).
• If the LL is docked to the CM nose, it could provide emergency propulsion capabilities for the CM-OSM in the event of a problem with the PM.  brmj and I did the maths for this elsewhere and found that even in worst case scenarios for this with regards to masses, the LL would have enough fuel onboard to do a TEI burn on the CM-OSM.  This is a very attractive safety feature.
• If the LL is docked to the CM nose or body, the CM needs to be able to endure the forces of the LL pushing against it during launch – or we need a potentially weighty support frame inside the Falcon 9 fairing.  If the LL is in a hanger, the hanger frame can easily endure these loads.
• If the LL is docked to the CM nose, the spacewalk from the CM to the LL is much shorter and much more straightforward, which is good for safety.
  
• Perhaps most importantly, if the LL is docked to the CM nose, the LL needs to be designed in such a way that it can dock, which might entail a drastic redesign over our current plans, although it would probably be a redesign in the direction of minimalism.

As you can see, the pros and cons are relatively balanced.  I feel like the safety related pros for the nose option are greater enough that we should opt for it if we can solve the other issues, but solving them may not necessarily be straightforward.

What are people's thoughts on this?

I am also quite in favour of the nose docking option.  I wonder if the launch load issue could be simply dealt with by having the lander frame attach to a "clip" of some sort which was attached to the nose by heavy springs or hydraulic/penumatic shock absorbers?