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In return for U。S。 space cooperation and an infusion of hard currency； Russia in effect agreed to halt its sale of ballistic missile ponents to other nations； and generally to exercise tight controls on its export of strategic weapons technology。 In this Way； space bees once again； as it was at the height of the Cold War； an instrument of national strategic policy。
This new trend has； though； made some of the American aerospace industry and some key members of Congress profoundly uneasy。 Without international petition； can we motivate such ambitious efforts？ Does every Russian launch vehicle used cooperatively mean less support for the American aerospace industry？ Can Americans rely on stable support and continuity of effort in joint projects with the Russians？ （The Russians； of course； ask similar questions about the Americans。） But cooperative programs in the long term save money； draw upon the extraordinary scientific and engineering talent distributed over our planet； and provide inspiration about the global future。 There may be fluctuations in national mitments。 We are likely to take backward as well as forward steps。 But the overall trend seems clear。
Despite growing pains； the space programs of the two former adversaries are beginning to join。 It is now possible to foresee a world space station—not of any one nation but of the planet Earth—being assembled at 51° inclination to the equator and a few hundred miles up。 A dramatic joint mission； called 〃Fire and Ice；〃 is being discussed in which a fast flyby would be sent to Pluto； the last unexplored planet； but to get there； a gravity assist from the Sun would be employed； in the course of Which small probes would actually enter the Sun's atmosphere。 And we seem to be on the threshold of a World Consortium for the scientific exploration of Mars。 It very much looks as though such projects will be done cooperatively or not at all。
WHETHER THERE ARE VALID； cost…effective； broadly supportable reasons for people to venture to Mars is an open question。 Certainly there is no consensus。 The matter is treated in the next chapter。
I would argue that if we are not eventually going to send people to worlds as far away as Mars； we have lost the chief reason for a space station—a permanently （or intermittently） occupied human outpost in Earth orbit。 A space station is far from an optimum platform for doing science either looking down at the Earth； or looking out into space； or for utilizing microgravity （the very presence of astronauts messes things up）。 For military reconnaissance it is much inferior to robotic spacecraft。 There are no pelling economic or manufacturing applications。 It is expensive pared to robotic spacecraft。 And of course it runs some risk of losing human lives。 Every shuttle launch to help build or supply a space station has an estimated 1 or 2 percent chance of catastrophic failure。 Previous civilian and military space activities have littered low Earth orbit with fast…moving debris—that sooner or later will collide with a space station （although； so far； Mir has had no failures from this hazard）。 A space station is also unnecessary for human exploration of the Moon。 Apollo got there very well with no space station at all。 With Saturn V or Energiya class launchers； it also may be possible to get to near…earth asteroids or even Mars without having to assemble the interplanetary vehicle on an orbiting space station。
A space station could serve inspirational and educational purposes； and it certainly can help to solidify relations among the spacefaring nations—particularly the United States and Russia。 But the only substantive function of a space station； as far as I can see； is for long…duration spaceflight。 How do humans behave in micro gravity？ How can we counter progressive changes in blood chemistry and an estimated 6 percent bone loss per year in zero gravity？ （For a three… or four…year mission to Mars this adds up； if the travelers have to go at zero g。）
These are hardly questions in fundamental biology such as DNA or the evolutionary process； instead they address issues of applied human biology。 It's important to know the answers； but only if we intend to go somewhere in space that's far away and takes a long time to get there。 The only tangible and coherent goal of a space station is eventual human missions to near…Earth asteroids； Mars； and beyond。 Historically NASA has been cautious about stating this fact clearly； probably for fear that members of Congress will throw up their hands in disgust； denounce the space station as the thin edge of an extremely expensive wedge； and declare the country unready to mit to launching people to Mars。 In effect； then； NASA has kept quiet about what the space station is really for。 And yet if we had such a space station； nothing would require us to go straight to Mars。 We could use a space station to accumulate and refine the relevant knowledge； and take as long as we like to do so—so that when the time does e； when we are ready to go to the planets； we will have the background and experience to do so safely。
The Mars Observer failure； and the catastrophic loss of the space shuttle Challenger in 1986； remind us that there will be a certain irreducible chance of disaster in future human flights to Mars and elsewhere。 The Apollo 13 mission； which was unable to land on the Moon and barely returned safely to Earth； underscores how lucky we've been。 We cannot make perfectly safe autos or trains even though we've been at it for more than a century。 Hundreds of thousands of years after we first domesticated fire； every city in the world has a service of firefighters biding their time until there's a blaze that needs putting out。 In Columbus' four voyages to the New World； he lost ships left and right； including one third of the little fleet that set out in 1492。
If we are to send people； it must be for a very good reason—and with a realistic understanding that almost certainly we will lose lives。 Astronauts and cosmonauts have always understood this。 Nevertheless； there has been and will be no shortage of volunteers。
But why Mars？ Why not return to the Moon？ It's nearby； and we've proved we know how to send people there。 I'm concerned that the Moon； close as it is； is a long detour； if not a dead end。 We've been there。 We've even brought some of it back。 People have seen the Moon rocks； and； for reasons that I believe are fundamentally sound； they are bored by the Moon。 It's a static； airless； waterless； black…sky； dead world。 Its most interesting aspect perhaps is its cratered surface； a record of ancient ；catastrophic impacts； on the Earth as well as on the Moon。
Mars； by contrast； has weather； dust storms； its own moons； volcanos； polar ice caps； peculiar landforms； ancient river valleys； and evidence of massive climatic change on a once…Earthlike world。 It holds some prospect of past or maybe even present life； and is the most congenial planet for future life—humans transplanted from Earth； living off the land。 None of this is true for the Moon。 Mars also has its own legible cratering history。 It Mars； rather than the Moon； had been within easy reach； we would not have backed off from