A monopropellant single stage can lift geological samples from Mars to orbi
t. The proposed propulsion system uses previously demonstrated miniature pu
mp-fed hydrazine technology. Loading the propellant just prior to operation
avoids the prohibitive structural, thermal, and safety constraints that ex
isted during earlier mission phases. A 100-kg Mars liftoff mass is 86% hydr
azine, < 6% propulsion hardware, and > 6% payload and guidance. The useful
mass delivered to Mars can be increased by also using pump-fed hydrazine fo
r landing.