Mars Sample Return Using In-Situ Propellant Production

Recent studies of human missions to Mars clearly reveal that utilizing indigenous resources at Mars to reduce the quantities of propellants, life support gases, and other materials that would otherwise be transported to Mars can dramatically reduce the total mission cost. An investigation was undertaken by a team of engineers and scientists at the NASA Johnson Space Center to determine whether similar benefits could be realized for a small, robotic Mars Sample Return mission that produced some or all of its Mars-ascent and Earth-return propellants using Mars materials as feedstock. Our design is called the MARS ISRU SAMPLE RETURN (MISR) mission. Once landed on Mars, a surface stay time of 580 days is needed to allow Mars and Earth to re-align for the voyage home. During this period, an automated production plant operates to slowly manufacture propellant. Though several attractive chemistry options exist and are being investigated, the MISR Team has chosen to manufacture and store oxygen from the principal constituent of the Martian atmosphere — carbon dioxide. Seventy-five percent of the mass of the propellants needed to lift off Mars and return to Earth will be oxygen produced in-situ. The fuel will be propane, which has high performance and is both easy to transport from Earth and to store on Mars. While on the surface, MISR will collect 2.5 kilograms of Martian rock, soil, and atmosphere samples using a microrover that is teleoperated by scientists on Earth. The samples will be placed in separate, sealed containers within a Sample Return Capsule. It is a mission constraint that no Martian materials come in contact with the Earth's biosphere. Once the MISR Sample Return Capsule is on its way home, a combination of a protective bio-bag and a pyrotechnic outer skin layer will ensure that no extraneous Martian materials are attached to the outside of the capsule.