Propellant-less vehicles can mine asteroids for water, making fuel for heavy rockets available in space.
Electric solar wind sail could make two-way manned Mars flights possible by making fuel available in Mars orbit, researchers claim.
In the heart of this scheme is the electric solar wind sail (E-sail) which provides propellant-less transportation within the solar system, thus enabling economical asteroid mining. The E-sail, which was invented in Finland in 2006, utilises long, charged tethers to convert natural solar wind momentum flux into spacecraft thrust.
After finding a suitable water-bearing asteroid, a mining unit using the E-sail can be sent to extract the water from asteroid soil. Water can be split into hydrogen and oxygen and liquefied, and the liquid hydrogen/oxygen (LH2/LOX) mixture can be used as fuel. The E-sail vehicle can ferry the extracted water and fuel to the orbits of Earth or Mars to be used to fill the tanks of manned vehicles travelling between Earth and Mars, researchers said.
According to Pekka Janhunen, a researcher in the Finnish Meteorological Institute, and colleagues the E-sail could provide essentially free logistics in the solar system outside of Earth’s magnetosphere.
Due to the exponential nature of the rocket equation, intermediate fuelling reduces the launch mass dramatically.
During the trip, asteroid-mined water could also be used as radiation shielding of the manned module to reduce the launch mass further.
With cheap propellant available in Mars orbit, there is also the option of fully propulsive landing on Mars which eliminates the need of a massive and expensive heat shield.
The E-sail facilitated Manned Mars Initiative (EMMI), could provide a fundamentally new, economically sustainable way to approach manned Mars flights, researchers said.
The running costs of the EMMI are not expected to much exceed those of maintaining the International Space Station, they said.
