Researchers have claimed that an electric solar wind sail (E-sail) could make continuous bidirectional manned Mars flights possible by utilizing water mined from the asteroids.
E-sail that was invented in Finland in 2006, utilizes long, charged tethers to convert natural solar wind momentum flux into spacecraft thrust. It provides propellant-less transportation within the solar system, and enables economical asteroid mining.
A mining unit using the E-sail can be sent to extract the water from asteroid soil after finding a suitable water-bearing asteroid.
The liquid hydrogen/oxygen (LH2/LOX) mixture can be used as fuel after splitting water into hydrogen and oxygen and liquefied.
The extracted water can be transported the extract water. It can fuel to the orbits of Earth or Mars to be used to fill the tanks of manned vehicles travelling between Earth and Mars.
According to Pekka Janhunen, a researcher in the Finnish Meteorological Institute, asteroid mining can be made practical with the help of e-sail as it provides free logistics in the solar system outside of Earth’s magnetosphere.
The launch mass get reduced dramatically due to intermediate fuelling and the exponential nature of the rocket equation. Asteroid -mined water could also be used as radiation shielding of the manned module to further reduce the launch mass during the trip.
There is also the option of fully propulsive landing on Mars with cheap propellant available in Mars orbit. The researchers said that the E-sail facilitated Manned Mars Initiative (EMMI) could provide a fundamentally new, economically sustainable way to approach manned Mars flights.
The researchers claimed that the running costs of the EMMI are not expected to much exceed those of maintaining the International Space Station.