CURRENT ISSUE

SUBSCRIBE

DIGITAL EDITIONS
RENEW | GIVE A GIFT
ARCHIVES
CUSTOMER SERVICE

RECENT

OUR BLOGS

RECENT

TOPICS

RECENT

TOPICS

RECENT

TOPICS

RECENT

TOPICS

RECENT

TOPICS

RECENT

TOPICS

RECENT PHOTO GALLERIES

TOPICS

The Future of NASA

Michael Griffin is gearing NASA up to build a moon base. Is he paving the way to Mars or jeopardizing the future of American space exploration?

By David H. Freedman|Friday, September 01, 2006

RELATED TAGS: SPACE FLIGHT, MARS

null You might think that by now NASA would have mastered all there is to know about the flight characteristics of a long, pointy tube, but NASA is nothing if not thorough. So it is that Gary Erickson and two other veteran NASA aerodynamics researchers at the agency's Langley Research Center in Hampton, Virginia, are huddled around a 33-inch-long version of what may be mankind's ticket to the cosmos. "We wouldn't want it to be any longer," explains Erickson, "because shock waves from the model would bounce off the wind-tunnel walls and catch the end of the model."

The teeniness of the test subject and its staid laboratory setting seem almost comical compared with the dramatic plans that hang on the full-scale incarnation of this piece of hardware and its cousins, which are also being wind-tunnel-tested in extreme miniature, here and at two other NASA facilities across the United States. They are nothing less than the future of America's manned space program. These rockets and crew capsules so far exist only as small models, crude foam mock-ups, and computer-graphics files. In many ways, though, their nonreality is a mere technicality. NASA and its allies have already made the big design decisions, started awarding the contracts, and most important, budgeted the money (well, some of it) to build a successor to the star-crossed space shuttle. There's even a name for NASA's new rockets: Ares.

Ares is the Greek god of war, who became better known to the world as the Roman god Mars. Michael Griffin, NASA's cherubic and relentlessly optimistic administrator, hopes that names are destiny: He is promising that Ares will launch mankind outward to the fourth planet of our solar system, a dream of virtually everyone ever involved in the space program, but one that has been abandoned repeatedly in the past. Griffin may well be the person to see to it that NASA finally pulls it off. "I am an unabashed supporter of space exploration in general and of human spaceflight in particular," Griffin told Congress in 2003, when he called for a human return to the moon and a trip to Mars. "I believe that the human spaceflight program is in the long run possibly the most significant activity in which our nation is engaged." On April 13, 2005, Congress confirmed President George W. Bush's appointment of Griffin to the position to make it happen.

The new space vehicles will carry astronauts back to the moon starting near the end of the next decade. These ramping-up missions will include the building of a lunar base and scientific projects like the construction of a telescope on the moon's south pole. They will also give NASA an opportunity to shake off the missteps that for more than three decades have left us stuck in low Earth orbit with a troubled space shuttle and a largely irrelevant International Space Station—programs that together will have cost roughly $250 billion by the time they are paid for. In other words, NASA is poised to pick up human space exploration where Apollo left off in 1972. It's no coincidence that the designs for the new astronaut-toting vehicle have eschewed the rakish, Tomorrowland look of the shuttle in favor of the workaday blunt-gumdrop-on-top-of-a-paper-towel-tube approach of NASA's 1960s heyday.

Griffin's plan sounds solid enough: Learn to put astronauts on the moon for months at a time, then use the hardware and experience to continue on to Mars. A closer look reveals a scheme fraught with peril and potentially insurmountable obstacles, though not necessarily of the sort you might expect given the vast distances and harsh environments involved in a trip to Mars. "I don't think there's any big problem from a technical point of view in executing this mission," says R. John Hansman, an aeronautics and astronautics professor at MIT. "The problem is whether NASA has the right program for executing it." Specifically, say Hansman and a wide range of other space experts, Griffin has committed most of NASA's expected funding for the next several decades to a program that stands a very good chance of falling far short of the Red Planet, thanks to what may prove to be a trillion-dollar price tag. Meanwhile, NASA's scientific programs are already being choked to free up funds for the manned program.

As a Texas hold 'em poker fan might put it, Griffin has gone all in. He's pushed all the chips toward the center of the table in what may be one of the biggest bets in the history of human endeavor. If the cards break favorably, he'll probably be hailed as the visionary administrator who roused space travel from its somnolent state and laid the groundwork for humans setting foot, for the first time, on another planet. If they don't, he'll have set NASA up to squander hundreds of billions of dollars while consigning some of the most ambitious science projects ever conceived to the trash heap.

Despite all those images we've seen over the years of buzzing mission control centers, fiery launchpads, and exotic test chambers, a walk by NASA's bland headquarters at the corner of Third and E Street in downtown Washington, D.C., is a good reminder that the agency is at its core a government bureaucracy. Still, there are times when even a bureaucracy can break free of its ordinary confines and achieve the spectacular.

NASA got the call in January 2004 when President Bush addressed a group at the agency's headquarters. Chastised and inspired by an investigative report on the shuttle Columbia accident that bluntly described a failure in leadership for manned space exploration, Bush called on NASA to begin developing the space vehicles to carry astronauts back to the moon by 2020, then build a lunar base, and finally send a crew to Mars. "Humans are headed into the cosmos," he declared. Six months later the House of Representatives approved the mission 383 to 15, and the Senate followed by unanimous consent.

Many NASA insiders enthusiastically approved. Charles Bolden, a Marine fighter pilot in Vietnam, a two-time pilot and two-time mission commander of the space shuttle, and later a NASA assistant deputy administrator, had long chafed at what he saw as high-level neglect of human space exploration. He greeted Bush's speech with relief: "It wasn't quite Kennedyesque, but the president said space exploration is important for humankind and the U.S., and that's something we in the space program have been trying to get a president to say for a long time."

Bush's 2005 nomination of Griffin as NASA chief, which gave him responsibility for turning that vision into an actual space program, likewise met a warm reception. While most presidential nominees can count on savage grilling in congressional hearings, the Griffin nomination was notable for its utter absence of hostility or even significant skepticism. Expertise? The man holds six advanced degrees in science, engineering, and business, and he was head of the space department at Johns Hopkins University's Applied Physics Laboratory. Management know-how? He led major divisions at Orbital Sciences Corporation. Agency savvy? He held high-ranking positions at both NASA and the Strategic Defense Initiative, better known as the Star Wars program. Even beyond that impressive paper record, Griffin had shown himself in previous appearances before Congress to be outspoken, decisive, and bold, a man who would be willing to light a fire under resistant bureaucrats and waffling politicians. "We did not retreat from the moon because of technical difficulties, we did not fail to go to Mars because of technical problems, and we have not taken 20 years to put a space station in orbit because of technical matters," he told Congress in 2003. "In each case the issues are matters of politics and leadership." In particular, Griffin made abundantly clear his belief in the Big Mission—getting humans out into the solar system.

Anyone who doubted Griffin's resolve to keep Americans flying into space was set straight in the days leading up to this July's launch of the space shuttle Discovery. Griffin ordered the launch to proceed, overriding no-go assessments by the agency's chief engineer and top safety officer. The officials, along with many others in the agency, were concerned that falling foam at launch could damage the shuttle's heat-resistant tiles, as happened to Columbia in 2003, and leave the shuttle unable to reenter the atmosphere safely. "This is a risk worth taking at this time to get us back on track in space," Griffin insisted. With stakes this high, he decided, the gamble was worth it.

null Dean Eppler, a geologist from NASA's Johnson Space Center, tests a 210-pound Mark-III space suit designed for easy mobility on the moon.

Griffin seems ready to apply that same decisiveness and risk tolerance to the moon-and-Mars gambit. Under his direction, NASA quickly came up with specifics about how to do it. Within five years, human space exploration will have grown from just 10 percent of the agency's budget in 2006 to more than 40 percent. NASA will use that money to fund the development of an astronaut-carrying Crew Exploration Vehicle that will replace the shuttle, a rocket to launch it, and a "heavy lift" rocket to transport cargo. The first tests of the CEV's rocket are scheduled for 2009, with manned flights to low Earth orbit beginning by 2014 (even that hard-charging schedule will leave a gap in America's manned spaceflight program after the planned retirement of the shuttle in 2010). In 2018, the CEV will rendezvous in orbit with a lunar lander and a "departure stage," a rocket that will carry both lander and CEV to the moon. We will be up to our ankles in lunar dust for the first time in nearly 50 years.

This detailed agenda has certainly reenergized much of NASA. "Anyone under 50 here has never had a chance to work on a new space vehicle from the start," says Greg Brauckmann, a NASA Langley aerodynamics and thermodynamics researcher who joined the agency in 1980, when the shuttle was already completed. Most work since then has been on experimental vehicles that never made it into production. "It feels pretty good to work on something that's going to fly," he says.

So far, NASA's efforts have centered mainly on sorting out the aerodynamics of the CEV and its rocket, along with a launch-abort system and a "service module" that stays attached to the CEV until shortly before reentry, providing it with power and propulsion. Since late last year, NASA engineers have been sticking models of these vehicles in Mach-10 wind tunnels, and even firing them out of large guns, to identify possible flight instabilities. The initial launch-abort tower design proved to be a potential source of flight wobble at around Mach 1.5, for example. "When you're able to identify these sorts of things and fix them, that's when morale goes through the roof," says Langley engineer Bill Tomek. The contract to build the CEV, which could eventually be worth $10 billion, is scheduled to be awarded this month to either Lockheed Martin or a joint Boeing and Northrop Grumman team.

A mock-up of the Crew Exploration Vehicle, including, from top, the pilot's seat, the exterior, and an interior configured to carry either four astronauts to the moon or up to six to Mars or the International Space Station. It will also make unpiloted cargo deliveries to and from the station. At 16.4 feet wide, the CEV has a volume approximately three times that of its predecessor, the Apollo capsule.

Now comes the deflating reality check: The long road to Mars may come with a price tag that will cause plans to fizzle well before we make it back to the moon. A stark acknowledgment of a mismatch between goals and budget realities came in February, when, after vehemently vowing not to take "one thin dime" from NASA's space-science efforts to fund human spaceflight, Griffin announced he was doing just that. In NASA's 2007 budget request, he canceled substantial increases previously scheduled for space-science funding, which would now remain almost flat through 2011. Funding for the Big Mission, by contrast, would multiply more than fourfold. Between now and the end of the decade, then, NASA science would receive a total of $4.7 billion less than projected in 2005. Manned space exploration would receive $6.9 billion more. Griffin was pushing more chips into the pot.

This budget shift still won't come close to solving the problem, says Marco Caceres, a senior space analyst at the Teal Group, an aerospace and defense research firm. "It's sexy to talk about the moon and Mars, but it's going to be at least 2 or 3 times as expensive as NASA is estimating, and most big aerospace programs end up being 5 to 10 times as expensive as original estimates," he says. "We spent $100 billion and 30 years to build the space station, it's still not complete, and that's just hardware in low Earth orbit."

Griffin won't put a price tag on going to Mars, but NASA has released enough information over the years to permit some back-of-the-envelope calculations. The agency has predicted that getting to the moon will cost $104 billion (about 55 percent of the cost of the Apollo program in today's dollars, according to Griffin), and studies dating back to the 1960s predicted that a Mars mission would cost at least five times as much as getting to the moon. A price tag of $500 billion, then, is not unreasonable. At current funding rates, that would keep NASA off Mars for at least 50 years. In 1989 a detailed three-month study headed by Richard Truly, then the chief of NASA, put the cost at about $800 billion in today's dollars. Caceres thinks NASA will need as much as $2 trillion to complete its mission.

Scott Horowitz, a former shuttle commander who as NASA associate administrator for exploration systems heads up the agency's manned program, shrugs off accusations that the glorious moon-and-Mars agenda is seriously underfunded. "The bottom line is, the program has to fit in the current $16 billion profile," he says, referring to NASA's annual budget. He does not promise that this budget will be enough to get astronauts to Mars, however. Instead, he echoes a refrain heard frequently from Griffin: Americans won't complain about giving NASA more money once they understand what a tiny a piece of federal spending the agency accounts for. "We as a nation quite literally spend more on pizza than we do on space exploration," Griffin told Congress in October 2003. "NASA is 0.6 of a percent of the federal budget," Horowitz adds. "I do a lot of speaking to groups around the country, and you'd be amazed how many hands go up when I ask how many people think NASA's share of the budget is larger than 20 percent."

Abstract discussions of NASA's paltry budget might play well in some community halls, but they are unlikely to change many minds in Congress, which constantly hears the same argument from just about every agency in the country. In July the Senate Appropriations Committee unanimously approved an extra $1 billion in funding for NASA, but the ultimate fate of that bill remains highly uncertain. In fact, space experts see several ways the "paltry budget" argument could end up backfiring.

First of all, the high cost of reaching the moon, even if everything happens on time and on budget, may actually drain the enthusiasm for space exploration. "My concern is we go back to the moon, start building a lunar base, and because of funding problems—which there will be—we'll decide that going to Mars is noble but we can't afford it," says former shuttle commander Bolden. After the heady successes of Apollo, and in the midst of a highly motivating cold war, President Nixon asked for Mars plans but then blanched at the estimated cost and settled for the space shuttle alone. Congress and Nixon didn't even fund the final planned Apollo missions. "No one—no one—involved in the space program intended for us to go into low Earth orbit and stop there, but fiscally that's all we could do," Bolden says.

A second, related concern is that costs could careen out of control long before we ever return to the moon. The aerospace companies that NASA is enlisting to build Ares and the CEV inevitably run into cost overruns, delays, and operating problems. That is just par for the course with enormous, contractor-based projects, says John Pike, director of GlobalSecurity.org and a former director of space policy for the Federation of American Scientists. Yet the aerospace giants have so much clout with Congress that NASA often has no choice but to send big projects their way, Pike says. Once all that expensive hardware is under development, it's hard to kill the project—a kind of protection scheme for both NASA and the contractors. The downside is that NASA becomes dependent on ever-bigger budgets and cannot avail itself of cheaper, simpler approaches that might make a Mars mission more likely. For example, Pike says, NASA could have got by with a much smaller vehicle than the CEV, which is three times the size of the Apollo capsule, requiring a scaling up of the launch vehicle and everything else in the program. "It's not designed to carry astronauts, it's designed to carry contractors," he says.

A third problem is the steadily shrinking tolerance for risk at NASA, in Congress, and among the public. Some of this is obviously due in large part to the trauma of losing two shuttle crews, but it is also related to the loss of a sense of necessity. "During the Apollo program this nation was in a race, and we perceived the outcome as important to national security," says Lennard Fisk, former NASA chief scientist and a space science professor at the University of Michigan. "Now we may not be prepared to go ahead when we encounter setbacks."

Low risk tolerance broadly translates into higher costs. Will Marshall, an analyst at the Space Policy Institute in Washington, D.C., notes that Russia runs space missions for about a tenth of what NASA pays. "The Russians don't bother making sure everything is perfect; they're willing to slap something that seems pretty good on a rocket and have a go at it," he says. "NASA is hypersensitive to everything being just right, and they check it a billion times." Marshall thinks that policy ultimately lowers safety, because the best way to eliminate problems is to launch frequently to keep learning and improving; operating at a tenth of the cost per launch could allow 10 times as many launches.

"The public needs to have a better understanding of risk," Horowitz acknowledges." A Vietnam fighter pilot had about a one in 400 chance of not surviving his first combat flight. The space shuttle flight risk was four times higher than that. If we're going to Mars, the risk is going to be even higher." If the public isn't prepared to accept the consequences of such a hitch, the program could come screeching to a halt.

Fortunately, NASA's boosters—and its critics—also have a lot of advice about how Griffin could tip the scales more strongly in favor of making it to Mars.

A good first step, some say, would be to skip the return to the moon. That suggestion has some surprising sympathizers, including NASA's own head of human exploration. "I've been asking that question for 15 years: Why not just go straight to Mars?" Horowitz says. "As some say about the moon, 'Been there, done that, got that badge.'" He quickly adds that he now supports the NASA party line: It is prudent to work out any kinks in the new systems within rescuable distance of Earth, a lunar base will provide experience with surviving in an alien environment, and there's plenty of great science still to be done on the moon. Even Griffin has acknowledged the advantages of heading directly to Mars, but he emphasizes the downside. "It can be done, and it will be cheaper, but the risk to both the mission goals and to human life will be significantly higher," he told Congress in 2004.

Then again, whatever may go wrong on a Mars mission won't necessarily show itself on an earlier trip to the moon. It's not as if the shuttle hadn't been put through its paces before we lost the Challenger in 1986, and that experience didn't save us from later losing the Columbia. In reality, say a number of NASA analysts, the biggest reason the White House and NASA want to go to the moon first is because it can happen soon enough to provide some payback for the politicians who support it. "It's not that we couldn't afford a mission to Mars," says R. John Hansman of MIT. "It's that it wouldn't take place within a timescale that is politically useful. So we end up going on a shorter mission that is of less societal benefit but that's achievable in that time frame."

Griffin is betting that a lunar program could also rally broader public support. He hasn't hesitated to play the China card in urging Congress to back a return to the moon. "How are we going to feel when one of the Apollo lunar landing flags is returned to Earth and displayed in a museum—in Beijing?" he asked Congress in 2003. Although it is the Russians, not the Chinese, who have publicly stated their intentions to head to the moon, China is considered the more worrisome nation by far on Capitol Hill. Creating a sense that we are once again locked in a lunar space race with a rival superpower might be an easy way to get the country behind NASA's budget. "We're a competitive country," says John Logsdon, director of George Washington University's Space Policy Institute. "The idea of competing with China in a race to the moon is an act of political artifice."

Whether NASA aims for sooner or later, seeing the Mars mission through will depend heavily on whether there is a way to make it less costly. Actually, a more appropriate question might be: Could NASA have possibly designed a more expensive way to get to Mars? "My advice to Mike Griffin," Pike says, "is to lock himself in a room with Burt Rutan and other people who know how to get things done successfully, quickly, and cheaply." Rutan is the renegade aerospace engineer whose company, Scaled Composites, backed by billionaire entrepreneur Paul Allen, designed and built SpaceShipOne, the first reusable private spacecraft to breach the edge of outer space twice in a week, winning the $10 million Ansari X-Prize in 2004. The point of that exercise was that the project was run by a tiny, innovative team at high speed and low cost. Scaled Composites has designed and built 26 new aircraft in 30 years this way, working out of a few corrugated-metal buildings on a desolate tract of the Mojave Desert in California, a world away from the giant aerospace contractors hobnobbing around Washington, D.C.

In fact, an entire industry of nimble space-vehicle ventures has sprung up in recent years, including SpaceX, headed by PayPal founder Elon Musk; Armadillo Aerospace, started by computer-game developer John Carmack; Blue Origin, a pet project of Amazon founder Jeff Bezos; and SpaceDev, which came up with the novel rocket engine that powered SpaceShipOne. SpaceX is working on the capability to launch satellites into orbit for around a third of the $70 million or so that Boeing typically charges.

Griffin loudly sings the praises of tapping into this sort of entrepreneurial energy, and the agency is bringing at least the sheen of it to its new plans. NASA is running a competition that will select a private company to provide $500 million in cargo- and crew-ferrying services to the International Space Station and has chipped in $2 million toward a new $2.5 million X-Prize competition for a lunar-lander-type vehicle. Horowitz expects more of this in the future. "We're seeing some new players, like Burt Rutan and others, who have some real innovative designs," he says. "Maybe some of the ideas are too innovative. But they might get us the thing we're after for a more reasonable cost."

While competitions and prizes suggest that Griffin is eager to change NASA's image as a slave of big contractors, there's no sign that this sort of thinking will spill into the way the agency pursues its core-mission hardware. That's a missed opportunity, some of the new space entrepreneurs assert. "I think we could do it for around $5 billion," Elon Musk of SpaceX says about going to Mars. Pike doubts that Musk could do a multiperson Mars mission for less than $100 billion, but that would still be one-fifth or even less the price NASA would most likely pay were it to stick to a conventional course.

Ultimately, NASA's future depends not on better mission concepts and cheaper hardware so much as on the agency's ability to convince the public that space exploration is a crucial part of human destiny. "The problem with the president's vision is that there's no sense of urgency to it," Pike says. "He's the first American president since his father who has no idea why we have a space program. Up through Reagan we had competition with the Russians, and Clinton had cooperation with the Russians. Space was always a foreign policy initiative for us, and now that leaves NASA a 'how' agency with a 'why' problem." The public's interest could simply fade away, leaving America, a nation of immigrants and pioneers, without a frontier to explore for the first time in its history.

Posing the problem that way suggests a solution, however. What motivates people to open up frontiers has always been the desire to get away from problems back home, or the promise of riches. NASA could tap into either, or both.

Griffin told Congress in 2003, "The proper goal of a publicly funded space program is to enable the human settlement of the solar system." That is, the best reason for blazing a trail to Mars is to begin the process of opening up an alternative to living on Earth. "If the dinosaurs had had a space program, they'd be around today," Horowitz says, paraphrasing Carl Sagan. That's a joke, of course, but he says NASA is starting to take the "Earth II" idea more seriously. Even Stephen Hawking has been pushing this idea lately. With global warming, the increasing availability of nuclear weapons to unstable nations, and the growing possibility of bioterror, we won't necessarily have to wait around for an asteroid to make life on Mars suddenly seem appealing. "Is NASA making the settlement idea a priority?" Horowitz asks. "No, but people aren't getting slapped down for saying it as much as before. It had been totally taboo because of the giggle factor."

As for the promise of riches, the commercialization of Mars exploration would seem ideologically in tune with the current administration. Oddly, Bush has said nothing about it, and Griffin has played down the idea. The giggle factor may again be at work. Claims that companies will be profitably strip-mining Mars, operating fuel stations there, or welcoming tourists who have sold their homes to afford a Mars ticket do, admittedly, seem a little loopy.

On the other hand, even far-fetched ideas can resonate with the public. Seeing the gutsy crew of a SpaceShipOne-style vehicle line up to make their own big gamble on a trip to Mars might be enough to inspire the public, and Congress, to help pony up the funds. On a smaller scale, that kind of public-private competition led to the decoding of the human genome far more quickly and cheaply than almost anyone expected. Griffin seems open-minded enough to steward this sort of change, if Congress is pushed into backing him.

All of that depends on whether the public still feels stirred by the magic of space exploration. Certainly the twin rovers on Mars and the intrepid Cassini spacecraft dodging around Saturn's rings have generated a powerful sense of wonder, yet those are exactly the kinds of projects that are at risk as Griffin places his bet on human voyagers, not mechanical surrogates.

If in the end we the public remain unmoved by the notion of a crewed mission to Mars, then maybe the human race ought to stay home for a while. A science-rich and manned-flight-poor NASA won't be such a terrible thing. We will still get to see what we are missing out there, if only through robotic eyes. Even if we lose Mars as an escape hatch, maybe NASA science will give us the tools to keep Earth habitable—which, when you think about it, is a pretty sane trade-off.

Where Does Your NASA Dollar Go?

The $16.8 billion 2007 budget request for NASA—roughly half the size of the National Institutes of Health budget but three times as large as that of the National Science Foundation—will support an uneasy mix of manned programs and pure science. Facing limited funds, NASA administrator Michael Griffin slashed many science programs, including astrobiology (down 50 percent in the 2007 request) and the development of nuclear propulsion systems for spacecraft (down 97 percent). Although Congress may restore some funding to science, Griffin's decision to focus on sending humans to the moon and Mars means that more tough decisions loom. By 2011, if current projections hold, manned space exploration will grow from just 10 percent in 2006 to more than 40 percent of NASA's budget. Agency activities fall into five categories:

Space Operations: $6.23 billion. Currently the most expensive component of NASA. Funds the space shuttle ($4.06 billion) and the International Space Station ($1.81 billion). Space and Flight Support ($370 million) covers astronaut health and safety and Earth-based communications with missions.

Science: $5.33 billion. Covers unmanned research missions. Earth-Sun System ($2.21 billion) funds efforts to understand Earth's weather and its changing climate. Solar System ($1.60 billion) supports continued operation of the Mars rovers, the Cassini spacecraft, and others. Universe ($1.51 billion) includes servicing the Hubble Space Telescope and developing its replacement.

Exploration Systems: $3.98 billion. Most of the money for the planned human exploration of the moon and Mars will come from here. Constellation Systems ($3.06 billion) funds the Lunar Landing, Extended Lunar Stay, and Mars Landing Capability programs, including development of the Crew Exploration Vehicle. Exploration Systems Research and Technology ($650 million) covers nuclear technologies to propel and power spacecraft. Human Systems Research and Technology ($270 million) explores the health dangers posed by spending time in space.

Aeronautics Research: $720 million. Includes funding for aviation safety, new propulsion systems, and NASA's wind-tunnel facilities.

Cross-Agency Support: $490 million. Funds interactions with industry, academia, and government. —Anne Wootton

null

Cost in Space

As NASA funnels money to the space shuttle and a return to the moon, a number of unmanned science missions have been delayed or cut. These are a few key examples.

1. Constellation-X Observatory (target date, 2017; cost, $2.5 billion)
These four satellites would act as one giant X-ray telescope, 100 times more sensitive than any other. Scientists planned to use it to explore galaxy formation, test Einstein's general theory of relativity, and probe the nature of dark matter and dark energy.

2. Jupiter Icy Moons Orbiter (JIMO, shown above) (target date, 2017; cost, $10 billion)
If life exists elsewhere in our solar system, scientists suspect it might be on Europa, an ice-covered moon orbiting Jupiter. JIMO would determine whether Europa has a buried ocean and find potential landing sites for future missions to search for life down below.

3. Terrestrial Planet Finder (target date, 2020; cost, $1.7 billion)

Get more information on NASA's "search for another earth," including a running counter of the number of known extra-solar planets (176 when the magazine went to print).

Visit the Web site of the Planetary Society, which is conducting a campaign called S.O.S.: Save Our Science, on behalf of NASA's 2007 science budget.

NASA's Outer Planets Assessment Group generates ideas and gives advice on exploring the outer solar system.