Some Like It Hot

1.

In the sky at dusk some midsummer evenings one could see two lights that evoked distinct lines of thought about the American space program and its uncertain future—Mars, rust-red and unblinking, suspended low in the southwest, and the Mir space station, a white dot that could be seen gliding overhead before disappearing into Earth’s shadow.

Aboard Mir, two Russian cosmonauts and an American astronaut were pretty much fighting for their lives. As the astronaut Jerry Linenger remarked, after he returned from his own recent tour of duty aboard Mir, the cries of alarm one least wants to hear on a space station are “Fire!” and “Depressurization!” and yet Mir suffered both within a matter of months. This pair of emergencies, set against a sobering series of ongoing breakdowns and mishaps—an estimated 1500 of them since Mir was launched, in 1986—had frayed the nerves of the spacefarers to an unsettling degree. After a collision with an automated supply vessel depressurized part of the station, the Mir commander, Vasily Tsibliev, radioed to Earth, “We are alive, thank God.” These are not heartening words, though they do attest to Tsibliev’s penchant for blurting out what’s actually on his mind—a tendency that led to his being blamed, briefly, for Mir’s mishaps, until a replacement crew promptly began running into problems of their own.

Meanwhile, in sharp contrast to Mir, the Pathfinder lander was engaged in its spectacularly successful exploration of a ruddy, rock-strewn wadi at the mouth of Ares Vallis, Mars. Data and photographs from the vehicle and its appealing little rover were being studied by scientists who hoped to find clues to what the Red Planet was like in balmier days, during its first millennium, when there were rivers and lakes there, and a thicker, warmer blanketing atmosphere. The mission attracted enormous public interest, generating one hundred million “hits” on the mission’s Internet website in a single day. That’s an astonishing number, larger than the combined audiences of the nightly news broadcasts on the three major commercial television networks, and one that challenges the common wisdom that people care about space exploration only if astronauts’ lives are on the line.

For decades, it has been assumed in Congress and elsewhere that public support of NASA programs depends on the drama of manned spaceflight. But this was never more than an article of faith, and it began to sound dated once astronauts no longer ventured to the moon, and automated spacecraft like Viking, Voyager, and the Russian Venera Venus landers were sending back evocative images of worlds millions of miles away. Now that the Internet has created a new medium in which the public is much more free to make its own choices, the vote seems to be going the other way. Millions of Internet users are finding that 3-D pictures and virtual reality landscapes of Mars and other planets, called up at their pleasure on their computer screens, create a sense of being there that compares favorably to the experience of watching astronauts float around in space.

Adding to the challenge posed to the manned program are its staggering costs, compared to unmanned spaceflight, and serious doubts about the relative merits of its mission. Manned spaceflight is inherently expensive. The cost of putting the Pathfinder robot on Mars—$250 million, all options included—is dwarfed by that of operating the space shuttle, which runs to half a billion dollars or more per mission, and by the $400 million that the US is paying Russia to fly astronauts on Mir. For the price of a few shuttle missions, we could be launching the modern equivalent of ambitious robotic missions—like Voyager, which sent two probes to the outer solar system, obtaining thousands of images of Jupiter, Saturn, Uranus, Neptune, and their many satellites, and which cost something over a billion dollars over the course of a flight that started in the 1970s and is still ongoing, as the craft explore space billions of miles from the sun.

Spending billions on manned spaceflight might well be justified if the missions made good sense, but it is precisely on this point that Mir and the shuttle are most vulnerable. The problem, simply put, is that nobody seems to know what they’re for. The shuttle was designed to ferry astronauts and supplies to and from a permanent space station, but after decades of planning and billions of dollars spent on seemingly endless rounds of drawing and revising blueprints, the “International Space Station,” as it’s now called, has not been built. Nor has any clear reason emerged for why it should be—unless one reverts to arguments about preserving America’s technological infrastructure in the aerospace industry, a laudable goal but one which could be accomplished in many other ways.

Meanwhile, with the exception of a few efficacious moments—most notably in servicing and repairing the Hubble Space Telescope, a spectacular but almost unique instance of symbiosis between the manned and unmanned programs—shuttle astronauts have been relegated to performing unimposing “microgravity” experiments and satellite-launching chores so uninspiring that at one point they took to styling themselves a “trucking company.” Nor is the shuttle much of a trailblazer. Unmanned spacecraft are probing space to unprecedented depths (radio signals from Voyager take almost eight hours, traveling at the velocity of light, to reach Earth) but the shuttle orbits at an altitude of under 250 miles—an excursion that, to paraphrase the late Isaac Asimov, is what the family car could do in a day’s drive if it could drive straight up. One of the safety concerns of shuttle mission directors is to make sure the shuttle doesn’t run into one of the thousands of satellites already up there. Presumably it is in part because the public has begun to understand just how low the shuttle flies, and how little it really does, that interest in the program has waned. While the Pathfinder website was reeling under the impact of all those hits, how many people had the slightest idea what seven astronauts were doing, “almost unnoticed,” in the words of one television commentator, as they spent the Fourth of July on shuttle Columbia?

The space station still looms on the horizon, as it has for decades, and journalists who ask why astronauts are risking their lives aboard Mir and the shuttle are told that through such efforts we can “learn more” about living and working in space. But such a rationale can be used to justify almost any activity, no matter how pointless. It is as if an inquiring fifth-century reporter asked Saint Simeon Stylites why he spent decades sitting atop a pillar and was told that Saint Simeon wanted to “learn more” about pillar-sitting. The International Space Station is a multibillion-dollar exercise in pillar-sitting. The danger is not that it won’t ever be built but that it will, and that the endless effort to keep it staffed and shipshape will swallow up not just its $20 billion projected cost but much more of NASA’s budget besides, thus reversing the hard-won gains in unmanned space funding that made possible a series of cost-effective missions, like Pathfinder, that are rekindling public excitement about nature beyond Earth.

In essence, the eddying-out of the American manned space effort is a lingering result of the end of the space race. It was thanks to the tonic effect of Soviet attainments in space, notably Sputnik in October 1957 and the orbiting of Yuri Gagarin in 1961, that John F. Kennedy was emboldened—on May 25, 1961, just six weeks after Gagarin’s flight—to declare to Congress that the United States “should commit itself to achieving the goal, before this decade is out, of landing a man on the moon and returning him safely to Earth.” The Apollo project that ensued amounted to a singularly marvelous party for the newly minted National Aeronautics and Space Administration, which had only been established in 1958 but which, by the time Neil Armstrong set foot on the Sea of Tranquility eleven years later, was spending nearly 2 percent of the federal budget. With the moon race won, there ensued a morning-after hangover of epic dimensions, as NASA officials tried to figure out what to do next.

Imagination being harder to stockpile than rocket fuel, NASA reverted to the world’s best-known space exploration strategy, one that had been set forth nearly twenty years earlier by Wernher von Braun and his colleagues—whose expertise had given rise to the post-Sputnik joke that the Soviets were ahead in the space race because “their German rocket scientists are smarter than our German rocket scientists.”¹ Von Braun had outlined his plan in several popular books published in the early 1950s, some of them illustrated by the redoubtable technology artist Chesley Bonestell.² It envisioned astronauts aboard space shuttles constructing a gigantic space station in Earth orbit, from which base humankind would explore first the moon and then Mars.

The Apollo program had jumped that schedule by going straight to the moon, but now, with Apollo at an end, NASA went back to planning for a space station and a shuttle fleet. This seemed a bit quixotic—rather as if Columbus, after making four voyages to the New World, had proposed that Spain build huge cities on Madeira and the Azores, from which to dispatch aircraft carriers to Cuba—and in any event by the 1970s the public was losing its taste for grandiose space projects. The Vietnam War had stained the once-gleaming aerospace technology with blood, and the moon mission, carried out by military jet pilots and presented largely in the language of engineers (who disdain the unexpected), had come to be widely regarded as something of a bore.

Faced with such apathy and with the mounting cost of the war, President Nixon considered abandoning manned space exploration entirely. Its back to the wall, NASA responded with a series of steps that led it into boglands of deception. First, it compromised the design of the space shuttle to make it capable of a military mission—a wacky scheme in which the shuttle, in times of national emergency, would be launched and make a quick orbit or two for surveillance purposes, then return to its base. Few in the Air Force believed that in a time of crisis the generals would bother with launching a shuttle, but the Defense Department went along for the ride, with aberrant results that culminated in the construction of a shuttle pad at Vandenberg Air Force Base in California, an instant ruin that never launched anything.

Additionally, to reinforce its hollow warning that without a shuttle it would lack any means of sending heavy payloads into space, NASA scrapped the remaining specimens of its flagship heavy-lift rocket, the Saturn, a five-million-pound booster that had sent Apollo astronauts to the moon without a single failure. (The Saturn on display in front of the Johnson Space Center in Houston, gaped at by tourists like a Roman ruin in medieval times, is not a model but a real moon rocket; NASA simply threw it away.) To clinch the deal, NASA promoted the shuttle as an economical way to put satellites into orbit. This was patently absurd, as the shuttle in action was soon to illustrate in terms too dramatic to be disguised by any amount of clever bookkeeping. The space shuttle system weighs 4.5 million pounds at launch; its orbiter, which weighs a quarter of a million pounds when separated from its launching rocket, can release a payload of up to about 48,000 pounds—a fifth of the weight the Saturn booster could deliver to orbit. Although NASA told Congress that the shuttle would put satellites into orbit at a quarter of Saturn’s price, the real cost turned out to be five times more than the Saturn booster it replaced. Whatever its other merits, launching a satellite with the space shuttle is about as cost-effective as mailing a postcard after first sealing it in a cast-iron safe.

Nor did the shuttle fly with anything like the frequency predicted. NASA forecast 572 shuttle missions by 1991; in reality, it flew only 35. Since payrolls and most other overhead costs remain constant regardless of the number of missions, fewer flights mean a greater cost per flight—something to keep in mind when assessing today’s space agency estimates of what it will take to support the International Space Station.

The nadir of NASA’s decline came when the shuttle Challenger exploded, shortly after launch on the chilly morning of January 28, 1986, and an investigation of the crash by the commission led by William Rogers laid bare a space agency culture corrupted to the point of delusion by internal acceptance of the exaggerations and evasions it had been purveying to outsiders. Many on the commission were eager to support NASA in the interest of defending national pride, but the most memorable words came from the physicist Richard Feynman, a Nobel laureate, who insisted on filing a separate report of his own. A masterpiece of plain talk, the Feynman document concludes that “reality must take precedence over public relations, for nature cannot be fooled.”³

What the space agency needed, if it was to have any realistic hope of recovering from its tailspin, was an administrator who combined a reformer’s resolve with the political acuity to remain in power through changes in administrations. Unexpectedly, that’s what it got, when in 1992 President Bush appointed Daniel S. Goldin to head NASA. Born in the South Bronx in 1940, Goldin is a no-nonsense thinker—he used a Lego building-block set to show how the space station could be built with interchangeable parts—and a dedicated infighter who suspects that he’s not doing his job unless he steps on a few toes. His motto is “smaller, cheaper, faster, better,” and to a considerable degree he has delivered on it. He trimmed NASA’s bloated work force, cut manned spaceflight costs from nearly half the NASA budget to under 40 percent, and virtually eliminated cost overruns, which had been averaging 75 percent on major programs.

Yet the space station, which Goldin saved from a budget-cutting Congress by turning it into a project for international cooperation, threatens to reverse many of his admirable reforms. Mir is a mess and the Russians have already failed to meet their financial obligations to even this relatively inexpensive precursor to the full-scale space station project, which, once under construction, could easily produce cost overruns dwarfing the worst excesses of the shuttle program. With the NASA budget expected to stay fairly constant at $13-14 billion annually for the immediate future, an over-budget space station would menace the survival of relatively austere unmanned projects like the Mars Surveyor probes scheduled for launch in 1998 and 2001, and the Pluto Express space vehicle—which must be launched by about 2001 if it is to fly past Pluto before that remote planet, now headed outward from the sun, gets so cold that its atmosphere collapses and becomes unobservable for another century.

And, of course, a budget-gulping space station could imperil NASA’s most venerable and ambitious goal, a manned mission to Mars.

2.

George Bush in 1989 made a Kennedyesque proclamation committing the nation to a manned Mars landing by the year 2019, but NASA priced the mission at $450 billion, Congress balked, and the Space Exploration Initiative, as it was called, has been moribund ever since. Yet Goldin remains enthusiastic about a manned Mars mission. “We could be on the surface of Mars before 2010, nine years ahead of when we said we would do it in 1989,” he told a National Space Symposium in Colorado Springs, but only, he added, if “the price is less than the annual cost of the space station.”⁴ The space station is budgeted at $2 billion a year during construction and $1.3 billion each year thereafter. That would put the total cost of a Mars mission at something under $20 billion. What makes Goldin think it could be done that cheaply?

The answer in two words is “Mars Direct.”

Mars Direct was conceived of in 1990 by a team at Martin Marietta (now Lockheed Martin) led by the spaceflight engineer Robert Zubrin, who outlines the plan in his book The Case for Mars. It is designed both to land astronauts on Mars cheaply and to make sure the landing is not just an Apollo-style “flags and footprints” media event but the first step in a campaign of genuine exploration aimed at eventual colonization of the Red Planet. It abandons Von Braun’s stepping-stone strategy and goes straight to Mars as soon as possible, without waiting to build huge space stations in Earth orbit or bases on the moon. “Mars Direct says what it means,” Zubrin writes.

The plan discards unnecessary, expensive, and time-consuming detours: no need for assembly of spaceships in low Earth orbit; no need to refuel in space; no need for spaceship hangers at an enlarged Space Station, and no requirement for drawn-out development of lunar bases as a prelude to Mars exploration. Avoiding these detours brings the first landing on Mars perhaps twenty years earlier than would otherwise happen, and avoids the ballooning administrative costs that tend to afflict extended government programs.

The plan’s key innovation is to send on ahead of the astronauts a robotic vehicle, called the Earth Return Vehicle (ERV), with a small nuclear reactor that would combine its on-board liquid hydrogen with carbon dioxide in the Martian atmosphere to make methane and oxygen—rocket fuel—and water. The astronauts would use the fuel to return to Earth from Mars, a technique that vastly reduces the payload required on the outbound leg.

Zubrin’s schedule begins in August 2005 with the launch, by a heavy-thrust booster direct from the surface of Earth, of the ERV. Six months later, the automated craft brakes in the Martian atmosphere to orbit, then aerobrakes a second time and parachutes to landing. (A technique something like this, but without the orbital episode, was used successfully in this year’s Pathfinder landing.) The ERV’s rover-borne nuclear reactor moves a few hundred yards away, settles in a small crater, and goes to work sucking in Martian air and reacting it with hydrogen fuel that it brought along. Zubrin estimates that the automated fuel plant could in six months have turned its original six metric tons of liquid hydrogen into eighteen times that much rocket fuel and water for use by astronauts on Mars and during their return to earth.

Zubrin calls this “living off the land,” and he is at pains to portray it as consistent with lessons learned from exploration in the past. “If we attempted to haul up to Mars all the propellant required, we indeed would need massive spacecraft requiring multiple launches and on-orbit assembly,” he writes.

The cost of the mission would shoot out of sight. It should come as no surprise that local resources make such a difference in developing a mission to Mars, or anywhere else for that matter. Consider what would have happened if Lewis and Clark had decided to bring all the foot, water, and fodder needed for their transcontinental journey…. A logistics nightmare would have been created that would have sent the costs of the expedition beyond the resources of the America of Jefferson’s time. Is it any wonder that Mars mission plans that don’t make use of local resources manage to ring up $450 billion price tags?

Once sufficient fuel is waiting for them, four astronauts blast off from Cape Canaveral in 2007 and fly to Mars. The trip takes 180 days, during which time their home in space, the “habitation module,” is tethered by a steel cable to the launch rocket’s final stage. Spinning the two vehicles around the fulcrum of the tether generates artificial gravity, sparing the crew the debilitating effects of prolonged weightlessness. At Mars, the astronauts jettison the rocket’s final stage, aerobrake into orbit, and land near the automated fuel vehicle that arrived three years before. If there’s a near miss, the astronauts can reach the fuel station by means of a rover they’ve brought along; it has a range of nearly 1,000 kilometers. If they miss by more than that, a second ERV, following them from Earth, can be targeted on their landing site. In any event the crew has enough supplies to last three years, so, as Zubrin writes in his no-nonsense way, “If worse came to worst, the four could just tough it out on Mars until additional supplies and another ERV could be sent out in 2009.” (Missions to Mars can be launched every two years, during favorable alignments of Mars and Earth.) Provided that all goes well, the crew explores Mars for eighteen months before returning home, and another, similar mission arrives on Mars every two years thereafter. The eventual goal is to colonize Mars. Zubrin estimates that by the year 2018 “an actual Mars settlement” would be founded, “above a geothermally heated subsurface reservoir, which will afford the base a copious supply of hot water and electric power.”

Engineers’ visions of future exploration tend to sound too good to be true (as, indeed, they usually are) yet they are difficult to criticize except on the level of specific details, a task that few can accomplish except for other engineers in the field. And, indeed, some in NASA have poked holes in the Mars Direct approach. But the strategy has won over many in the space agency, in part because it’s cheap. NASA has already adopted some of the ideas Zubrin presents, incorporating them into “Mars Semi-Direct,” a $55 billion “baseline” budget to be employed in the ongoing effort to design an affordable way to put humans on Mars.

The toughest issues have to do with safety. Much of the public support NASA enjoys is derived from national prestige. Wherever NASA flies, it carries the American flag; its triumphs evince the technological prowess and can-do spirit on which millions of Americans pride themselves, and its failures hurt that pride. Zubrin writes about how spacefaring should be a matter of “iron men and wooden ships, not wooden men and iron ships.” But iron men like Columbus and Magellan risked their own lives and those of their crews, and often lost: of the 270 men who set sail from Spain with Magellan, 253 never made it back. NASA cannot afford to gamble at anything like those odds. The Apollo program aimed for a 99.9 percent reliability, and probably achieved something like the 90 percent safety level attained by the shuttle. To fly at a 10 percent risk of death is daunting—it’s ten times more dangerous than driving a car, and two thousand times riskier than flying on a commercial airliner—but it’s still a lot safer than, say, the early days of aviation.

Freeman Dyson, of the Institute for Advanced Study, Princeton, has a range of practical experience in technology unusual in a theoretical physicist: he worked on strategic bombing in his native England during World War II and on nuclear power planning in the United States. In his recent books Disturbing the Universe, From Eros to Gaia, and Infinite in All Directions, he has offered more acute and commonsensical advice on technological research and development than is to be found in whole shelves full of the competition. His latest, Imagined Worlds, makes illuminating criticisms of what he calls “ideologically driven” technologies, which, because they symbolize national pride, are obliged to succeed.

Nuclear power he sees as one such technology. “So long as it is allowed to fail, nuclear energy can do no great harm,” Dyson writes, in a characteristically novel turn of phrase, but since failure couldn’t be tolerated, nuclear energy had to be presented as safe and clean and cheap and a blessing to humanity. The result was a campaign of deception worse than that of NASA’s darkest days. Rules for reactor safety and environmental impact were written so as to appear to fulfill the political commitment to safe, efficient nuclear plants, and accounts were juggled to make them seem profitable. The public reacted with growing distrust to what it correctly judged to be a smokescreen of official duplicity, and today it is virtually impossible to build a nuclear power plant anywhere in the United States.

Ideologically driven technologies, Dyson argues, discourage the rigorous experimentation without which no technology can properly evolve. Experimentation is meaningless unless at least some—in practice, most—of the experiments fail, yet a high failure rate cannot be tolerated in projects that are viewed as symbols of national pride. Dyson finds a telling example in aviation. Drawing on the writings of Nevil Shute Norway, an aeronautical engineer before he became a novelist and, as Nevil Shute, wrote On the Beach, Dyson estimates that

100,000 different varieties of airplane were flown during [the 1920s and 30s]…. Many of the pilots crashed and many of the airlines became bankrupt. Out of 100,000 types of airplane, about 100 survived to form the basis of modern aviation. The evolution of the airplane was a strictly Darwinian process in which almost all the varieties of airplanes failed, just as almost all species of animal become extinct. Because of the rigorous selection, the few surviving airplanes are astonishingly reliable, economical, and safe.

Many pilots and aircraft designers died testing airplanes, but their deaths were accepted by the public as sad but understandable setbacks along the path of individual innovation.

Dyson’s point—that real technological progress requires that there be room for failure—seems salutary, but how do we apply it to a manned Mars project? The thousands of intrepid aviators who risked and often lost their lives were free to do so because airplanes could be built cheaply. But there is no known cheap way to go to Mars. How can experimentalism and individual risk be brought to bear on a project where the table stakes run to billions of dollars?

Zubrin’s proposal is to offer a prize. “The U.S. government would post a $20 billion reward to be given to the first private organization to successfully land a crew on Mars and return them to Earth, as well as several prizes of a few billion dollars each for various milestone technical accomplishments along the way.” Why $20 billion? Because that, in Zubrin’s estimation, is what it would cost the government to land astronauts on Mars. What’s the incentive? Profit. Zubrin maintains that a private effort, free from the waste incurred by such government practices as “cost plus” contracts, could pull off Mars Direct for less than $10 billion, leaving investors free to pocket the difference.

Implicit in the Mars Prize idea is the assumption that a private Mars initiative could afford to entertain a greater degree of risk. Nobody wants astronauts to die, but public reaction to the death of an intrepid explorer or two engaged in private enterprise is likely to be less anguished than if fatalities occur as part of a national effort—and, in any event, the sponsors of privately-funded expeditions are shielded from public pressure to an extent not enjoyed by the NASA administrator and the politicians who control his funds.

Whatever one thinks of Zubrin’s proposals, they have the advantage of clarifying the relative merits of what he describes as three approaches to Mars exploration. One, the Mars Prize, he calls the “Gingrich approach,” after the House Speaker with whom he developed it. In another, the “JFK model,” the president commits the nation to a Mars landing by a specific date. The JFK approach depends for support on national pride and retains for the nation the fruits of spending—“an engineer’s paycheck, a welder’s take-home pay, a scientist’s research funds, a graduate student’s stipend [that] pay for innovations and inventions that will remain part of the nation’s intellectual capital and that may lead to new businesses or products for earthly use.” But it also depends on whether Congress or the nation is in an exploratory mood and is prepared to sustain it through years of spending. The third approach, which Zubrin calls the “Carl Sagan model,” after the late astronomer, relies on international cooperation. It shares both the glory and the expense, and allows mission planners to draw on each nation’s distinctive strengths, using, for instance, Russian heavy-lift rockets, Japanese electronics, and American airframe technology.

What NASA has today is a mix of the Kennedy and Sagan approaches that in some ways incorporates the worst of each. We have George Bush’s proclamation along with a few international ventures, such as Mir, in which the partners have not always been eager to pay their way. (The US has not invariably lived up to its own international science and technology commitments, either. The Japanese were furious when Congress first delayed and then canceled the Superconducting Super Collider, in which the Japanese had an investment.) Instituting a Mars Prize might put an end to the muddle, leaving NASA free to pursue its most dogged and quixotic mission, the International Space Station.

The size of a football field, the space station would be assembled from parts lofted into orbit by heavy-lift boosters, perhaps provided by the Russians, and would be serviced by the space shuttle. Hence it could provide a nexus of international cooperation—not only Russia but Japan, Canada, and the European Space Agency would be involved—while giving the shuttle something to do. The trouble is that nobody knows what the space station is for. Its advocates talk vaguely about space science, industrial applications, and “learning to live and work in space,” but such claims are difficult to take seriously when weighed against the project’s hefty price tag and the very real threat that it will incur serious cost overruns once it’s up there and lives are at stake. Unless the manned Mars mission is taken out of NASA hands, by passing a Mars Prize bill or something like it, the opportunity for human beings to land on Mars may be delayed indefinitely by space station costs.

Such a faltering of exploration would not be surprising or even unusual. Although in “Little Gidding” T.S. Eliot wrote, in lines that are frequently quoted by space-travel enthusiasts, that “we shall not cease from exploration,” as a matter of historical fact nations quite often cease exploring, usually because they run out of money or incentive or both. Much has been written about why Americans should go to Mars. Zubrin makes the case as well as anyone. He recalls the importance of the frontier to the American spirit, makes stirring references to the beauty and variety of the Red Planet—which, in a dry land area equal to that of the earth, has the highest mountains and largest valleys in the solar system and much else besides—and he notes, more pragmatically, that Mars “harbors resources in abundance that can enable the creation of an advanced technological civilization.” But nations have elected to forsake their long-term fortunes in favor of short-term gains before, and America could go down the same road.

The greater danger, perhaps, is that Americans will not realize what is at stake in the unmanned space programs—knowledge of the solar system and the wider universe from which the earth evolved. Among the projects now being planned are the Lunar Prospector and Mars Surveyor orbiters, the 2005 Mars Surveyor to bring back samples from Mars’s surface, the Stardust mission to return with comet dust, the Rosetta/Roland vehicle designed to land on a comet, the Ulysses Sun probe, and the Ocean Explorer and Biologic Explorer landers designed to search for life on Jupiter’s moon Europa and Saturn’s moon Titan, respectively. These endeavors have to do with understanding how our home planet got to be the way it is, and how its environment works today. Such matters are of more than academic interest. We are at present conducting uncontrolled experiments with global warming and ozone depletion here on Earth, phenomena in which our two neighboring planets provide quite grim cautionary lessons. Venus is a victim of runaway global warming; the temperature at its surface is hot enough to melt lead. Mars lost its ozone layer long ago; today its surface is bathed in ultraviolet radiation lethal as the lamp over a dentist’s sterilizing tray. We need to understand why, but we are unlikely to do so if most of our space exploration money is spent keeping astronauts on exercise bicycles aboard space stations that don’t venture any farther from the surface of Earth than the distance from San Francisco to Los Angeles.

NASA once had an ambitious “Mission to Planet Earth” program that was intended to provide better data about our planet’s atmosphere and oceans. Congress killed it, partly because it had fallen victim to appalling cost overruns. Terrestrial research from orbit will continue—expensively, from shuttle and space station, and, more economically, from missions like NASA’s Earth Observing System, a series of scaled-down satellites to be launched starting next year. But one wonders whether we will eventually be judged to have paid enough attention to the investigation, from space, of our home planet. It would be the ultimate irony if it turned out that the human species had forestalled inquiry into the still-mysterious essentials of planet management just when such ignorance had come to pose an immediate threat to our future.

—August 28, 1997