This image is a composite mosaic of four polar views of Mars, taken at midnight, 6 a.m., noon, and 6 p.m. local Martian time taken by NASA's Mars Reconnaissance Orbiter spacecraft and released October 16, 2006. This is possible because during summer the sun is always shining in the polar region. It shows the mostly water-ice perennial cap (white area), sitting atop the north polar layered materials (light tan immediately adjacent to the ice), and the dark circumpolar dunes. (NASA/JPL/MSSS/Handout/Reuters)
The first major mission to Mars should not be manned, it should be carried out by large construction robots, powered by a small nuclear reactor. The reasons are common sense.
1) Robots are on a one-way mission, so it can be substantially larger and more massive than a manned mission. Their spacecraft itself can be designed to be cannibalized for parts for their missions.
2) Robots have no time constraints. Even if they work at a slow pace, they can do it for years before people arrive. This is work that otherwise people would have to do at great expense and limited resources.
3) Much of what robots will do is "unscientific", such as digging hard rock tunnels for use as human habitations. If you don't need a human to do it, it's better to have a robot do it.
4) Robots can also find, mine and store water in habitat cisterns. In doing just these two things, digging and reinforcing tunnels and mining potable water, the duration of human missions could be extended by a year or two.
5) To get to Mars and back, an large orbital "shuttle" spacecraft may be built, which does not land. It carries other spaceships back and forth, to and from Mars orbit, so these manned ships can carry cargo instead of fuel. By sending robots first, it would be a good way to test this shuttle.
6) Robots do not stop working when humans arrive. In fact, they could be designed to also be used as human operated machinery to do far more complex tasks like building runways and constructing surface habitats that extend out from the tunnel system. Eventually the underground tunnel system could be enlarged enough to sustain a permanent colony.
