It has been proposed that we already possess the knowledge and technology needed to terraform Mars. <ref name=Mars One> [http://www.mars-one.com/mission/roadmap]</ref> While this may be true, that is not to say that the existing technology is ideally suited for the task, or that all-important processes are in place to achieve use the knowledge we possess. Long before the first "official" launch of a Mars terraforming project (hereafter) referred to as "project"), there will certainly have been a host of project-specific groundwork laid in preparation. Not respective of general progress in the generic arena of space work and travel, Mars-oriented work has been progressing at universities, space agencies and space-associated companies worldwide.
Following are project related research, processes, and technology which we will need in preparation for Terraforming Mars.
Orbital storage of fuel for future use Edit
Short of a radical new form of propulsion technology, we know the probable candidates for propulsion of a manned mission to Mars, all of which are tried and true forms of [propellant|rocket propellant]. As the project matures, the types of propulsion will likely demonstrate a diverse range of types and technologies, but early efforts will most certainly be of a more basic (solid, liquid, or gas) nature, which will require bulk storage in orbit.
There is no shortage of "wish list" items that await transport to the International Space Station (ISS), but it turns out that many launches actually have "room" left over. On a launch-by-launch basis, the volume limits of the various crafts which lift material into orbit play more of a role than weight.
Currently, the ISS dumps excess hydrogen and methane into space, as both are extremely explosive and dangerous to store in bulk. Given the extreme cost of launching anything into space, including lighter-than-air gasses, devising a safe method of storing both hydrogen and methane is critical. In future, orbital fuel depots will be an integral part of any interplanetary mission.
Obviously the main concern in fuel storage in proximity to the ISS is the danger to life and the facility, in the event of a catastrophic explosion. Such a disaster is not an unlikely scenario, in consideration of the number of small, fast, untracked objects in orbit. An estimated 170 million pieces of junk <ref name="NASA"> </ref>, larger than 1mm encircle the earth in a virtual death-defying gauntlet which all space vehicles must constantly traverse. A bit of metal which strikes the ISS with no meaningful result may well provide the "spark" required to ignite methane or hydrogen. Planning for the near-certainty of such a collision is critical. I is not enough to provide self-sealing technology to mitigate venting of the stored gas; it is necessary to prevent it entering the vessel portion of the storage craft entirely, as such interlopers are likely to breach at an extremely high temperature - hot enough to ignite volatile gasses.
Mining the Moon for Rocket Fuel Edit
Finally, the term "gas station" will not be a factual inaccuracy. Space farers will certainly begin their voyages by topping up their various gas reservoirs while in orbit.
The hydrogen and methane donated by the ISS will be a drop in the bucket compared to the volume that will be needed. Unless we are willing to sacrifice our atmosphere to pollutants using traditional launches, we will mine those and more elements on the moon, making them available in orbiting "gas stations."