ASTS is pleased to propose to demonstrate the feasibility of using an aerospike nozzle to provide a dramatic increase in payload capability to the two-stage, all-solid-propulsion Mars Ascent Vehicle (MAV). The aerospike features a well-known altitude compensation capability, but the MAV operates in near-vacuum conditions so cannot take advantage of that aspect. Instead, the aerospike nozzle, at a comparable ~200:1 area ratio as is currently baselined for MAV, will be considerably shorter than a traditional bell nozzle. Thus, for a fixed motor length, a shorter aerospike nozzle will allow us to lengthen the motor case itself, thereby enabling us to load a substantial amount of additional propellant than the baseline. The resultant improvement in propellant fraction will provide significantly higher payload performance compared to the baseline--our preliminary calculations show that up to 40% additional propellant can be added to the each motor.