Down the road a bit, we Earthlings will become Marslings. Before the first colony is established on Mars quite a bit of work will be done to prepare the way for the first settlers . Currently there are thousands of really bright people working on the challenges of reaching Mars. A recent article on ArXiv (at the Cornell University Library) proposes a new way to get there and the best part is that it allows us to launch a mission at anytime and cuts 25% of fuel requirement to do so.
Researchers Edward Belbruno and co-author Francesco Topputo have published a paper detailing this new path to Mars, and the physics behind it. The paper Earth–Mars Transfers with Ballistic Capture , provides a detailed proposal that offers a number of advantages for Mars missions.
Quoting the authors,
This includes substantially lower Dv at higher altitudes, flexibility of launch period from the Earth, gentler capture process, first transferring to locations far from Mars offering interesting new approaches to Mars itself, being ballistically captured into capture ellipses for a predetermined number of cycles about Mars, and the ability to transfer to lower altitudes with relatively little penalty. The initial capture locations along Mars orbit may be of interest for operational purposes.
It is interesting to note that this method has the advantage of allowing a mission to launch at anytime without the usual requirement of waiting for the planet to be in the right position in its orbit using the Hohmann transfer method. This sets up the ballistic capture transfer method as the go to approach for Mars supply missions as they could be launched monthly, creating a supply chain to Mars.
For manned missions this method does require 4-8 months of added time to a typical mission, and this extended mission requirement comes with a host of concerns such as the radiation exposure, added on-board supplies for the travelers, and of course the stress of spending long periods of time in the tight confines of the spacecraft.
While it may not be the best option for manned flight, the ballistic capture transfer method could work well for supplying the Marslings. The establishment of supply lines to support a colony is nothing new. What is new is the challenge of doing it in space. We know how wagon trains supplied the early settlers of America, the next step is just a planet away.
ArXiv: Earth–Mars Transfers with Ballistic Capture
Scientific American: A New Way to Reach Mars