One of the longstanding challenges of space exploration is the huge amount of thrust it takes to escape the Earth's atmosphere. That kind of power is also expensive to create, so the holy grail of the last decade or so has become more efficient and inexpensive ways to move around space. SpaceX is working on reusable rockets, but another nascent concept involves "sailing" on the solar wind.

We first detailed the electric solar sail developed by Dr. Pekka Janhunen of the Finnish Meteorological Institute in 2008, and now it's back in a paper recently published in the journal Acta Astronautica. The report outlines how combining the sail with the mining of asteroids for water to convert to fuel could be the best way to conduct manned missions to Mars in the future.

You can consult our original article for more details on the workings of the sail, but the central concept involves using dozens of very long thin conducting filaments and an on-board electron gun to create a field that the solar wind then "pushes" against to propel the craft.