I have made a few posts on space propulsion over the past year (see ‘propulsion’ in tag cloud). I saw the article “Mars in 3 day? NASA Researches are Working on a Photonic Propulsion System” and though it warranted some attention.
It is easy to understand how light ‘pressure’ can be used to ‘sail’ a space craft using a large sail. It is a little harder to accept that powerful lasers could supply more of a push than the light from our own sun. But this is an idea that NASA is currently investigating.
In theory using photonics propulsion, a 100 kg automated space craft could be flown to Mars in just three days. A manned space craft would be much heavier and would take up to a month. The NASA research team headed by Philip Lubin claims that lasers could power a space craft to 30% of the speed of light in 10 minutes.
Lubin published the technical paper “A Roadmap to Interstellar Flight” in April 2015 with the technology explained in more detail.