**5. Conclusions**

For exploration and exploitation of the Martian moons, both chemical propulsion and electric propulsion orbital transfer vehicles (OTVs) were assessed. For large payloads of 10 to 50 MT, the nuclear electric propulsion (NEP) OTVs require a small fraction of the chemical propulsion OTV propellant mass. If 10 MT payload masses can be manifested together, the 50 MT NEP OTV would be a more propellant efficient OTV option over a using five 10 MT NEP OTVs. The Phobos to 100,000 orbit transfer required the largest mission delta-V and the largest OTVs; therefore, this OTV design can encompass all the suggested OTV missions.

For small 1 MT payloads, chemical propulsion OTVs were more efficient than NEP OTVs. However, the NEP OTV can enable several special missions. Radar science missions and observations can be conducted; a small 1 MT payload might be left in orbit about a Martian moon and the NEP OTV can use a high power radar to transmit signals through the moon. The smaller payload would gather the reflected radar signal and allow more accurate determination of the moons internal structure.

Mining water on the Martian moons may be used for resupplying propellants to chemical and NEP OTVs. Mining systems on the surface may be able to provide the needed water to make hydrogen and oxygen. However, the water mass fraction on the surfaces Phobos and Deimos may be small; the estimates have a wide range from 1x10−5 to 1x10−1. Deep caches of water ice may also exist, but these deep caches may be difficult to mine. In the best estimates, 100's of MT of water may be wrested from Mars' moons, assisting in make Mars exploration truly Earth independent.
