The Case for Mars Read Online Free PDF Page A

and relayed to Earth, nothing can prepare the crew for the sight of the Martian landscape stretching before them. The soils are rust colored, littered with sharp-edged rocks, large and small. In the distance are small hills and dunes. The landscape is akin to the deserts of America’s southwest, save for the skies, which are a ruddy, salmon color. There’s an immense amount to be done just after touchdown, but they take the moment to gaze out at Mars, to savor the fact that no creature with eyes to see has ever gazed out on this vista in the four-billion-year history of Mars and Earth.
    With the Beagle safely down at the landing site, the Ares 2 ERV lands some 800 kilometers away, where it begins the process of filling itself with propellant. It will be used as the ERV for the second human expedition, which will arrive at its site in Hab 2 in 2009, along with another ERV that will open up Mars landing site number three. As the missions proceed, a network of exploratory bases will eventually be established, turning large areas of Mars into human territory.
    The crew of the Beagle will spend five hundred days on the Martian surface. Unlike conventional Mars mission plans based upon orbiting mother ships withsmall landing parties, Mars Direct places all the crew on the surface of Mars where they can explore and learn how to ll arrive the Martian environment. No one has been left in orbit, vulnerable to the hazards of cosmic rays and zero-gravity living. Instead, the entire crew will have available to them the natural gravity and protection against cosmic rays and solar radiation afforded by the Martian environment, so there is no strong motive for a quick departure. For a crew left in orbit during a conventional mission, there’s little to do but soak up cosmic rays, and that tends to create a strong incentive to limit the time allowed for surface exploration, generally to thirty days or so. This leads to spectacularly inefficient missions. After all, if it takes a year and a half for a round trip to Mars, a stay of only thirty days is rather unrewarding. Worse yet, the rush to get back home forces conventional missions to follow trajectories that require far more propellant. But that extra propellant alone won’t get a spacecraft back to Earth directly. Because Earth and Mars are constantly changing their positions relative to one another, “quick return” flight plan trajectories have to get a gravitational boost by swinging past Venus—where the Sun’s radiation is twice that at Earth.
    Even with such a substantial amount of surface time, the crew’s days will be filled with projects that will vastly expand our knowledge of the planet and pave the way toward future exploration and, eventually, human facilities and settlements. There will be the geologic characterization of Mars, which will begin to tell us the story of Mars’ past climatic history, how and when it lost its warm and wet climate, key clues to reviving Mars and perhaps saving the Earth. Geologic investigations will also include searches for useful mineral and other resources. Above all, astronauts will seek out easily extractable deposits of water ice or, better yet, subsurface bodies of geothermally heated water. Ice or water is key, because once water is found, it will free future Mars missions from the need to import hydrogen from Earth for rocket propellant production, and will enable large-scale greenhouse agriculture to occur once a permanent Mars base is established. Experimentation with agriculture is another item high on the priority list, and an inflatable greenhouse will be brought along for this purpose. The area of exploration that will seize the attention of the people of Earth, though, will be the astronauts’ search for Martian life.
    Images of Mars taken from orbit show dry riverbeds, indicating that Mars once had flowing liquid water on its surface—in other words, that it was once a place potentially friendly to life. The best