Physics of the Future: How Science Will Shape Human Destiny and Our Daily Lives by the Year 2100

radiation), and for drinking once it is purified. So this discovery could shave hundreds of millions of dollars off any mission to the moon.
    This discovery may mean that it will be possible for our astronauts to live off the land, harvesting ice and minerals on the moon to create and supply a permanent base.

MIDCENTURY (2030 TO 2070)
    MISSION TO MARS
    President Obama, when he journeyed to Florida in 2010 to announce the cancellation of the moon program, held out the prospects of a mission to Mars instead. He supported funding for a yet-unspecified heavy booster rocket that may one day send astronauts into deep space beyond the moon. He mused that he might see the day, perhaps in the mid-2030s, when our astronauts would walk on Mars. Some astronauts, like Buzz Aldrin, have been enthusiastic supporters of the Obama plan, because it would skip the moon. Aldrin once told me that the United States has already been to the moon, and hence the real adventure lies in going to Mars.
    Of all the planets in the solar system, only Mars seems to resemble earth enough to harbor some form of life. (Mercury, which is scorched by the sun, is probably too hostile to have life as we know it. And the gas giants—Jupiter, Saturn, Uranus, and Neptune—are too cold to support life. Venus is a twin of the earth, but a runaway greenhouse effect has created a hellhole: temperatures soar to 900°F, its mostly carbon dioxide atmosphere is 100 times denser than ours, and it rains sulfuric acid. Walking on the Venusian surface, you would suffocate, be crushed to death, and your remains would be incinerated by the heat and dissolved by the sulfuric acid.)
    Mars, on the other hand, was once a wet planet, like earth, with oceans and riverbeds that have long since vanished. Today, it is a frozen desert, devoid of life. Perhaps microbial life once flourished there billions of years ago or may still live underground in hot springs.
    Once our nation has made a firm commitment to go to Mars, it may take another twenty to thirty years to actually complete the mission. But getting to Mars will be much more difficult than reaching the moon. In contrast to the moon, Mars represents a quantum leap in difficulty. It takes only three days to reach the moon. It takes six months to a year to reach Mars.
    In July 2009, NASA scientists gave a rare look at what a realistic Mars mission might look like. Astronauts would take approximately six months or more to reach Mars, then spend eighteen months on the planet, then take another six months for the return voyage.
    Altogether, about 1.5 million pounds of equipment would need to besent to Mars, more than the amount needed for the $100 billion space station. To save on food and water, the astronauts would have to purify their own waste and then use it to fertilize plants during the trip and while on Mars. With no air, soil, or water, everything must be brought from earth. It will be impossible to live off the land, since there is no oxygen, liquid water, animals, or plants on Mars. The atmosphere is almost pure carbon dioxide, with an atmospheric pressure only 1 percent that of earth. Any rip in a space suit would create rapid depressurization and death.
    The mission would be so complex that it would have to be broken down into several steps. Since carrying rocket fuel for the return mission back to earth would be costly, a separate rocket might be sent to Mars ahead of time carrying rocket fuel to be used for refueling the spacecraft. (Or, if enough oxygen and hydrogen could be extracted from the ice on Mars, this might be used for rocket fuel as well.)
    Once on Mars, it might take weeks for the astronauts to get accustomed to living on another planet. The day/night cycle is about the same as on earth (a day on Mars is 24.6 hours). But a year is almost twice as long. The temperature on Mars never goes above the melting point of ice. The dust storms on Mars are ferocious. The sand of Mars has the consistency of talcum powder, and dust storms that engulf the entire planet are common.
    TERRAFORM MARS?
    Assuming that astronauts visit Mars by midcentury and establish a primitive Martian outpost, there is the possibility that astronauts might consider terraforming Mars, that is, transforming the planet to make it more hospitable for life. This would begin late in the twenty-first century, at the earliest, or more likely early in the twenty-second.
    Scientists have analyzed several ways in which Mars might be