TOO PRAGMATIC FOR THE AV CLUB:

Mission to the Moon: How We'll Go Back -- and Stay This Time: With the iconic Space Shuttle nearing retirement, the pressure is on NASA to design a new manned vehicle -- one that will deliver us safely to the lunar surface by 2020 before building a lasting lunar base. From ensuring a safe launch to getting the vehicle back on the ground, here's an inside look at some of the toughest challenges Orion's engineers are now confronting. (David Noland, March 2007, Popular Mechanics)

Not long after the inaugural launch of Endeavour (the fifth and final shuttle) in 1992, NASA began contemplating a new generation of manned spacecraft. The agency selected Lockheed Martin to design the X-33 single-stage-to-orbit space plane in 1996; it was abandoned five years later because of technical difficulties. The agency then considered the less ambitious Orbital Space Plane, or OSP. But the second shuttle disaster, the loss of Columbia in 2003, forced NASA to rethink its entire manned space program. It dropped the OSP and suggested another concept: the Crew Exploration Vehicle (CEV).

After reviewing an initial round of proposals, NASA announced the basic design parameters in September 2005. Many space buffs were disappointed. Instead of Lockheed Martin's proposal for a sleek, high-tech space plane, first previewed in PM's June 2005 issue, the agency decided to build its new spacecraft with off-the-shelf technology. The squat "spam-in-the-can" capsule that NASA unveiled was at first glance a dead ringer for the 1960s-era Apollo spacecraft. Even the launch vehicles were to be pieced together using warmed-over components from both the current shuttle and the Apollo-era Saturn boosters.

By relying on existing technology, the design would allow for more efficient construction, narrowing the gap between the shuttle's retirement in 2010 and the next manned flight. But it also stirred a hot debate within the aerospace community. "NASA's attitude seems to be that Apollo worked, so let's just redo Apollo," says Charles Lurio, a Boston space consultant. Burt Rutan, the mastermind behind the rocket SpaceShipOne, likened the new CEV to an archeological dig. "To get to Mars and the moons of Saturn, we need breakthroughs. But the way NASA's doing it, we won't be learning anything new."

Scott Horowitz, NASA's associate administrator for Exploration Systems, defends the agency's approach. "Sure, we'd love to have antimatter warp drive," he says. "But I suspect that would be kind of expensive. Unfortunately, we just don't have the money for huge technological breakthroughs. We've got to do the best we can within our constraints of performance, cost and schedule."

The result, as NASA boss Michael Griffin puts it, is "Apollo on steroids" -- a new-and-improved version of what was, as even critics must acknowledge, mankind's greatest technological feat. Recently dubbed Orion, the CEV will share Apollo's conical form, but be one and a half times as wide (16.5 ft.) and have more than double the habitable internal volume (361 cu. ft.)­, allowing it to carry six astronauts to the space station and four to the moon.

Orion also will boast a number of new tricks, such as hands-off autodocking and the ability to autonomously loiter in lunar orbit for up to six months. Its dual-fault tolerant avionics, based on those of the Boeing 787, will be able to sustain two computer failures and still return the vehicle to Earth. The avionics also will have open architecture, which means they can be easily updated and modified.

Although the CEV concept has been percolating for well over a year, the real design work -- putting detailed flesh on NASA's basic frame -- is only just beginning at the agency and at Lockheed Martin, NASA's prime contractor. Engineers face a bewildering array of decisions, a complex matrix of tradeoffs among cost, weight, time, safety and mission. "We're struggling mightily to figure out the ramifications of all these requirements," says Bill Johns, Lockheed Martin's chief engineer for Orion. "It's a huge coordination problem that keeps me awake at night."

From ensuring a safe launch to getting the vehicle back on the ground, here's an inside look at some of the toughest challenges Orion's engineers are now confronting.