Dave Scott, who visited the moon in 1971, thinks the next generation of lunar pilots will have it much easier than he did. He likens his Apollo 15 landing to "the old barnstorming days, when guys used to take these old World War I airplanes and land in a farm field, in the grass, with no lights, and trees all around."

The next lunar landing, he expects, won't be nearly as seat-of-the-pants. "Everything will be wired. When they come down the line the guidance is going to be better, the knowledge of the surface will be better." And, it goes without saying, the new vehicle is expected to be a great improvement over its predecessors.

There are great reservoirs of wisdom among the veterans of the Apollo program. At 73, Scott still keeps his hand in the game as an aerospace consultant. So do some of the engineers who built his lunar lander at Grumman Aerospace back in the 1960s.

John Connolly made pilgrimages to Bethpage, New York, where Grumman is based, to seek the counsel of these veteran engineers before he moved from NASA headquarters in Washington, D.C., to the Johnson Space Center in Houston. There he will coordinate the team creating conceptual studies of the new Lunar Surface Access Module.

"Some people, their heroes are astronauts," says Connolly, as we're standing in the National Air and Space Museum in Washington, next to a squat, four-legged contraption that ranks among the great engineering triumphs of the 20th century: The Apollo Lunar Module, or LM. "The guys who dreamed up this ugly flying vehicle are my heroes."

Six Apollo landers, including Dave Scott's Falcon, are now on the moon, having transported astronauts there between July 1969 and December 1972. A handful of others are in museums around the United States. This particular vehicle, LM-2, never traveled in space. It didn't need to, because the first LM checked out so perfectly during an orbital test in January 1968 that a second test was deemed unnecessary.

"These guys [the Grumman engineers] in many ways pulled off the impossible," Connolly says. "They built a machine that had never been imagined before. Not only did they build it, but it worked perfectly every time."

That's a big achievement to follow. The new LSAM, if the schedule holds, will carry astronauts back to the moon in 2018, half a century after the first lunar voyages.

"I was absolutely a child of Apollo," Connolly says. "As a nine-year-old, I was the kid sitting in front of the TV with my nose 12 inches from the black-and-white screen watching Neil and Buzz walking on the moon. I had all the models of the Saturn V and the LM and everything else that day."

He turned that fascination into a NASA career, and counts himself lucky to be "working on things that very few people get the honor to work on." Yet much of his career has been spent in the bureaucratic backwaters. While NASA focused on the shuttle and the space station, Connolly and a small band of forward thinkers at Johnson conducted study after study of missions that could get the agency back to the moon if it ever got the call. There was the First Lunar Outpost concept of 1992, and the Human Lunar Return of 1996-a cut-rate, let's-just-do-it scheme that would have put two spacesuited astronauts into an open-cockpit moon lander that looked unnervingly like a rocket-powered jet ski.

None of these plans went anywhere, of course. "There were a number of years where 'exploration' was a dirty word at the agency," Connolly says.

Then came the 2003 Columbia accident, and a dramatic, White House-mandated change of course. No more circling Earth. Returning people to the moon, and using it as a training ground for Mars, would be the space agency's new plan. So for the past two years, Connolly and his colleagues at NASA headquarters have been developing the Architecture (a word NASA uses with the same reverence fundamentalists accord to "Scripture") for accomplishing their new mission.

The Architecture calls for sending four astronauts at a time to the lunar surface, compared with Apollo's two. Instead of spending three days on the moon, they'll stay a week. And rather than being confined to a narrow band of landing sites around the lunar equator, they'll be able to land anywhere, even the poles, where scientists believe ice in the soil could be converted to fuel and drinking water.

These improvements over Apollo result largely from an advantage in rocket power. Not only are modern propulsion systems more efficient than those of 40 years ago, but NASA is also taking a different approach this time, launching the moon vehicles on two separate rockets with a combined 150 metric tons of lift. In comparison, Saturn V had 130 tons.

LSAM's additional lift power will enable it to be bigger, better, and in every way more capable than its predecessor. In cargo-only mode, with no crew, its carrying capacity will be 21 tons, more than the weight of the entire LM.

But will it look very different? No matter how many years have passed or how many studies have been conducted, the physics and engineering practicalities of landing on the moon drive the design inexorably toward what the Grumman engineers came up with decades ago. "We might have wanted the LSAM to look like the Millennium Falcon," says Connolly, with a trace of wistfulness. "But it will probably look like the Apollo LM."

The best way to do lunar exploration would be a "direct-direct" option, straight from Cape Canaveral to the surface of the moon. But that requires a rocket that can lift 200 tons to Earth orbit, says Connolly, and "we're just not going to build a launcher that big."

The LSAM lander will go on a large rocket, along with the Earth departure stage needed to reach the moon. A smaller rocket will then deliver the crew (in an Apollo-style capsule called the Crew Exploration Vehicle) to Earth orbit. There the CEV and LSAM will link up, the departure stage will fire, and three days later the still-joined vehicles will enter a 60-mile-high lunar orbit, from which the LSAM will descend to the moon's surface. NASA calls this big rocket-small rocket combo its "1.5 launch" option.

The study team quickly settled on a two-stage lander, same as that in Apollo, with a descent stage topped by a smaller ascent stage that brings the crew back up to lunar orbit following their adventures on the surface. In orbit, they'll return to the CEV capsule for the journey home.

Here the new plan again diverges from the old one. There will be no Mike Collins waiting in lunar orbit to greet Neil and Buzz -- the CEV will be left unattended.

Separating the new lunar module into pieces will be even more important in 2018 than it was in 1969, when NASA's goal was just to land astronauts on the moon and bring them back safely.

This time, the missions are only prep work for something far more ambitious-a lunar outpost where small crews will live for up to six months at a time. The early missions will likely all land in the same location, incrementally adding descent stages and other hardware that will become the building blocks for the new base.

One piece that will be especially useful to leave on the moon is the LSAM's airlock, which represents one of the most significant improvements over the Apollo LM. The moonwalkers of the 1960s struggled with the fine, powdery dust that covered their spacesuits. Back inside their tiny one-room cabin, it got everywhere-in the machinery, in their eyes, in their throats.

Scott said that moon dust even got in the connectors between the backpack and the spacesuits."You could almost hear them grind after three days," he said. He ranks dust as "the major problem for a long stay."

Mike Griffin, who became Administrator of NASA last year, was particularly eager to liberate the next generation of moonwalkers from lunar dust. So the Architecture team added an airlock, or dustlock, to the LSAM that will function like a mudroom in a suburban home -- a place where astronauts can remove their dirty things and avoid tracking the mess inside.

Airlocks have other advantages. With an airlock, the main cabin always stays pressurized, and the airlock acts as a transition zone between the shirtsleeve environment and the vacuum outside. Say all four astronauts are on a moonwalk and one suit develops a leak. Without an airlock, all four have to come inside at once and stay there, since any later entrance would expose the unprotected crewmember to the lunar vaccum.

The outer structure of the LSAM cabin will likely be a cylinder, similar to the large pressurized cans that make up the International Space Station's living and working spaces. The airlock could be a smaller, attached cylinder, though it needn't be.

In some designs, says Connolly, "we're talking about just putting an extra bulkhead and a hatch into [the LSAM] cylinder." But it might be preferable to have the airlock hatch closer to the lunar surface instead of placing it 15 or 20 feet off the ground, reachable only with a long ladder. The study team played with different options, including a kind of split-level design in which the astronauts descend a tunnel before heading out the airlock. The spacecraft's designers are still working to determine the exact configuration.

As for propulsion, NASA will go with the old reliable: liquid hydrogen/liquid oxygen engines for the descent stage, and hydrazine and nitrogen tetroxide for the ascent stage. The LSAM descent stage will use a modified version of the venerable RL10 engine, which entered service in 1963, just as Apollo was getting under way.

The descent engines for the lander have to be throttleable -- by the time of touchdown, they'll produce barely enough thrust to keep the vehicle from falling to the surface in the one-sixth gravity of the moon.

Today's RL10s can throttle down to 20 percent of their full thrust, but the LSAM engines will have to do better: 10 percent. That shouldn't pose a problem, thinks Connolly, but the achievement still requires some development work, and NASA may want to test these highly throttleable engines on robotic landers scheduled to begin visiting the moon as early as 2011.

Because the descent engines will be bigger and more powerful than the ones that flew on Apollo, engineers have had to consider the effects of the stronger blast on the lunar surface. When Pete Conrad piloted his lander to a touchdown in the Ocean of Storms during the November 1969 Apollo 12 mission, the rockets kicked up so much dust that for the last two minutes of his descent, he could hardly see anything below him. Could the debris from a more powerful blast fly up and hit the lander?

Connolly's team studied the problem, even watching old videos to analyze how the dust scattered. Most of it blew horizontally away from the landing site, not straight up. Conclusion: Rocket thrust shouldn't be a danger, at least for the LSAM itself. Some still worry about blast effects on previously landed modules, since the vehicles will probably touch down close to one another.

The single engine on the ascent stage also will use the same propellants used for Apollo, even though the combination wasn't NASA's first choice. The Architecture team originally wanted to use liquid methane fuel, in one of the lunar program's few nods to an even more distant future. Someday, when astronauts land on Mars, they'll need to live off the land as much as possible. Methane could theoretically be extracted from the atmosphere and turned into rocket fuel. So if the LSAM used methane engines, NASA could get early practice with a technology applicable to Mars.

The trouble is, no one has flown a methane rocket in space. A French-Russian demonstration project called Volga concluded last year that the technology looked promising, and a couple of companies have tested small-scale engines. But that's about it. Methane engines would have been one of the bigger leaps in the Architecture, and in the end NASA decided it was too big of one. The ascent engine absolutely, 100 percent, no kidding, has to work perfectly on the moon. Otherwise the astronauts are stranded.

Before trusting methane engines on the moon landers, NASA would have wanted years of experience flying them on the CEV. But with the CEV's debut planned for as early as 2010, there isn't time to develop such an important technology. So, reluctantly, NASA gave up on methane.

The decision to go with hydrogen fuel -- and lots of it, since the LSAM will need to shift the plane of its orbit as much as 90 degrees to reach polar landing sites -- influences other aspects of the design. The most striking example is the size of the fuel tanks. Hydrogen takes up more volume than denser fuels, so the descent stage tanks alone will be taller than the entire Apollo descent stage.

The 1960s lander was "a marvel of minimization" that strained the ingenuity of its builders, says Connolly. "They had to whittle away at every piece of metal on the vehicle to make it as light as possible." Current designers have more mass and volume to play with, so the LSAM will be substantially roomier than its predecessor, more like an RV than a minivan.

Connolly's team hasn't devoted much thought to amenities, but he predicts a few improvements that will mean a lot to future astronauts. They won't have to relieve themselves in bags, for example -- the LSAM will have some kind of toilet, even if it isn't as elaborate as the one on the space station. It might be something like the small, portable job the Russians have used on their Soyuz spacecraft for years. And whereas the Apollo astronauts ate strictly cold fare during their time on the moon, the LSAM should have a food warmer.

Last year, a group of astronauts and engineers at Johnson received a modest NASA grant to brainstorm what accommodations might be needed for long-term living on the moon. The group built a mockup of a lunar habitat in one of the center's warehouse -- like buildings in Houston, and invited a few veteran astronauts and scientists with Antarctic experience to attend their Lunar Habitation Systems Workshop. Three-time shuttle astronaut Mario Runco led the exercise.

One feature Runco is especially keen to include in a lunar module is windows. "You're talking to the windows-in-space guy," he says, and he's not joking. On the shuttle, where astronauts tend to eat on the run, he once made a point to spend a luxurious 40 minutes eating his spaghetti dinner while looking out the windows of the world's highest rooftop restaurant.

Because glass is heavy, the weight-conscious Apollo LM engineers could afford only tiny triangular portholes. LSAM's designers can probably do better than that, but will they? "Engineers reluctantly put in windows," laments Runco. "[And] the first things to go are the things for the crew."

But windows are more than just entertainment: Lunar pilots will surely want to see outside while landing on the moon. That is, if they're the ones actually doing the piloting -- which is a matter of some debate.

Here's how they did it in Apollo: The two astronauts stood during their descent to the lunar surface. Early in the landing sequence, the LM's computer handled all the necessary course corrections, even managing the dwindling fuel supply. Radar on the lander kept the computer updated on its position.

Then, just a few minutes before touchdown, the LM pitched over so the astronauts could look out the window and get their first good look at the landing site. If the commander liked what he saw, he could stay with the course the computer had chosen. He could nudge the path slightly. Or he could take full manual control and fly the landing himself, as Neil Armstrong did on Apollo 11, when he saw the Eagle heading for what looked to him like a field of boulders.

The Apollo landings were a joint effort between primitive (though then state-of-the-art) computers and very skilled pilots, and all six missions came down safely. On more than one landing, however, the LM came down in a crater, so it ended up tilting at a slight angle. Nothing too serious, but that may have been luck. Shortly after his dust-blind Apollo 12 landing, Pete Conrad told mission control he had come in guided only by instruments, adding: "It's a good thing we [trained in] a simulator." Weeks later, during his debriefing, he admitted, "I couldn't tell whether there was a crater down there or not."

When it comes to knowing their landing sites ahead of time, the LSAM pilots should have their Apollo forefathers beat hands down. The Lunar Reconnaissance Orbiter, scheduled to launch in 2008, will have long since mapped the moon's entire surface. Potential landing sites should be mapped to a resolution of a foot or two. Additionally, robotic landers may have photographed every rock and gully in the vicinity before the astronauts arrive. And advanced sensors on the LSAM, including laser ranging devices, could offer real-time hazard detection that cuts the chances of coming down in a bad spot to practically zero.

Connolly agrees that the tools will greatly improve landing. And he still pictures an astronaut at the controls in those final moments before touchdown. Landing on the moon is "very hard to do automatically," he says. "It's something, however, that pilots are very good at. In fact, picking out level, safe landing sites is sort of the whole idea of piloting."

That's way too old school for Missy Cummings, director of the Humans and Automation Laboratory at the Massachusetts Institute of Technology in Cambridge. Under contract to the nearby Draper Laboratory, Cummings has come up with designs of cockpit displays for the next generation of lunar landers. Both Draper and MIT are experienced in this area, having designed the guidance system and computers for the Apollo program, and Draper did the new work under a grant from NASA's exploration office.

The "glass cockpit" that Cummings envisions is light-years beyond Apollo's clunky switches and dials, beyond even current military fighters. The lunar astronauts would see an artificial view of their landing site from the surface as well as from above. Easy-to-interpret displays will show their trajectory, possible hazards, and remaining fuel. Computers would synthesize all the information, leaving the pilot to intervene only if something went wrong.

If the system is designed right, says Cummings, "anybody, anywhere, anytime should be able to control the lunar lander." The operator wouldn't even have to be on board. "You do not need 1,000 carrier landings or the Right Stuff to be a good lunar lander pilot," she maintains.

Lest anyone think this opinion comes from some pale computer geek who's never been closer to pilots than Row 12 of the red-eye to Boston, a brief word on Professor Cummings' background: Before she got her Ph.D., she was one of the first female naval aviators to fly the F/A-18 Hornet. Today she spends much of her time on the problem of controlling networked unmanned aerial vehicles (UAVs).

Because NASA also wants the LSAM to be able to land with no crew on board, delivering supplies in "cargo mode," Cummings says the agency's experience with remote-controlled landings on Mars is as relevant as the exploits of the Apollo astronauts. Her fear is that astronauts won't stand for some ground controller "piloting" the LSAM from afar. The same tension exists between Air Force pilots and UAVs, she says. "I was a fighter pilot. I was the most elite of the elite. And we're the ones who are most resistant to this change."

On this issue, Dave Scott, the Apollo 15 commander, comes down somewhere in the middle. "Airliners have had auto-land capability for a long time, but they still have the pilot up in front," he says. "So I would say if you get a lunar lander with an auto-land capability, you're still going to have the pilot looking out the window."

The question of who will pilot the LSAM doesn't need to be settled today, though. Right now Connolly has his hands full with big-picture design questions, particularly those that affect near-term development of the CEV and launch vehicles.

So Connolly consults with those who have been in his shoes-his predecessors, now retired from Grumman. "They are thrilled that NASA is coming back and talking to them," he says. "They are probably as excited today about going back to the moon as they were when they built this machine."

After posing with them for group pictures and hearing their war stories, Connolly would come back to asking them the same question. "How did you pull this off? How did you make this vehicle as reliable as it was?"

One way the LM engineers ensured quality was by "extensive, extensive testing," and Connolly wants to know how much he should budget for his test program.

That's another crucial difference between the 1960s and today: money. Once the Apollo engineers got deep into their work, the money just kept flowing, and there was little doubt NASA would follow through on its plan to reach for the moon. Could anyone make the same claim in 2006?

Having worked on more aborted return-to-the-moon plans than he can easily count, Connolly can only hope-or maybe it's better to say have faith-that this lunar lander will actually come to pass, just as the Architecture says it will.

Originally published in Air & Space/Smithsonian, April/May 2006 . All rights reserved.

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