Brainstorming complete list of what is needed on the lander | Lunar lander design | Forum

I hope everybody is as excited as I am by the recent rapid growth of the lunar lander conception.  The new Wiki page looks great, Rocket has done some good work.  But let's not rest on our laurels yet.  The current mass estimate on the Wiki page "does not include the weight of the seat, steps, descent motor, fuel tanks, life support, and electronics".  Let's work toward fixing this!

What will we need in these departments?

Has anyone given the descent motor any considerable thought/research?

Of course there will have to be an RCS.  I suppose most of the questions here are the same as those for the service module RCS situation.

With regard to life support, will we need anything at all or will we be able to fit it all inside the suit?

With regard to electronics:

There will need to be some sort of radio solution.  We are in a somewhat interesting situation here.  While the orbitting CSM is above the same side of the moon as the lander, the lander can use it as a relay to converse with Earth, requiring the lander radio to have a range only of our lunar obit's apogee, which is probably ~100 km.  I imagine the equipment for this sort of short range radio work could be fairly compact.  When the CSM is on the opposite side of the moon, I suppose we are in a radio blackout situation?  Or could we fit something small enough to communicate with Earth on the lander?

We will also need some sort of navigation solution for ascent and descent purposes, such as a radar and/or laser altimeter.  There seemed to be strong support on Reddit for doing away with these and instead measuring altitude using radio round-trip times between the lander and CSM, but I feel like this is a bad thing to rely on exclusively.  I don't know how accurately we will know the CSM's orbital parameters, so distance from the CSM may not be too informative.  So we will need some other solutions that we should start thinking about.

Can anyone think of any electronic requirements other than communication and navigation?

Obviously the radio and navigation solutions will need a power source.  We may want to opt for batteries on the lander instead of fuel cells, because the fuel cells would require an oxygen source.  So we should start thinking about battery options.  If we end up opting to send the lander out in advance on a low energy orbit, the batteries will need to hold their charge for several months which could be an important restriction when it comes to choosing a battery type.

Once we have a rough idea of all the equipment that needs to go on the lander we can start thinking about where to physically mount it.  We will have to come up with a mounting method that keeps the lander balanced and easy to control.