Solar wind might propel spacecraft to Mars and back
27 April 2015
The E-sail is a novel propellant-less technology proposed by Finnish researchers back in 2006. It uses long, charged tethers to convert natural solar wind momentum flux into spacecraft thrust.
Graphic courtesy of the Finnish Meterological Institute
According to researchers at the Finnish Meterological Institute, the E-sail might make asteroid mining feasible by providing essentially free logistics in the solar system outside of Earth's magnetosphere.
After finding a suitable water bearing asteroid, a mining unit could be sent by the E-sail to extract it from the asteroid's 'soil'; this would be achieved by heating the material and letting the evolving water vapour condense in a cool container. When the container is full, it would be separated from the mining unit and transported via an E-sail, either to an orbit around Mars or Earth, where it can be split into hydrogen and oxygen and liquefied. The liquid hydrogen/oxygen fuel would then be used to fill the tanks of manned vehicles travelling between Earth and Mars.
Intermediate tankings dramatically reduce launch mass. During the trip, asteroid-mined water could also be used as radiation shielding for the manned module and thus reduce the launch mass even further. With cheap propellant available in Mars orbit, there is also the option of a fully propulsive landing on Mars, which avoids the need for a massive and expensive heat shield.
According to the Finnish Meterological Institute group, the 'Electric solar wind sail facilitated Manned Mars Initiative' (EMMI) could provide a fundamentally new, economically sustainable way to approach manned Mars flights, and they believe its running costs would not be much more than those of maintaining the International Space Station.