Hi Ken -

Thanks for wandering on into this little corner -

For the Moon, the system trade offs are as follows:

1) hypergolics - cheap, well developed, but must be re-supplied from Earth
2) cryogenics - well developed, can be manufactured on Moon if water is confirmed, but storage is a bear - possibly too short for useful work to be done (i.l. the impactor detection facilities)
3) peroxide/alcohol - low specific impulse, possible explosive decomposition of peroxide, particularly in dusty environment - but could be manufactured from Moon water, if it exists, and peroxide can be converted into water and oxygen for life support

Fuel cells for power storage are always tops.

For Mars, the "Mars Enthusiats" can't see beyond Zubrin's "Mars Direct" - but solar thermal propulsion offers isp same as nuclear, 1100, plus re-usability. Orbits of Dr Aldrin's "cycler" type are best, with modularization of planetary ships to smaller components for launch from Earth surface.

It is currently not known if Mars has enough volatiles left to allow terraforming by impactor diversion. Perhaps a small laboratory/base of antartic size is the near term goal.

For Earth power generation from space, too little is known about effects of power beamikng on ozone, and effects on climate -

For EML points, defense use is never openly discussed. EML provides time for evasion of attacks on sensors and communication and control sats; EML also provides a stable location for nuclear power generation, which is good to power both sensors or defensive lasers. Let's hope that the diplomats are effective, and we don't have to spend the money to build one of these things, but in defense, hope is seldom enough...

ep