Mars Mission: Obama Wants an Asteroid. Republicans Want the Moon.

Washington is backseat-driving NASA's trip to Mars.

Washington's partisan divide is spreading all the way to space.

President Obama and many Republicans agree that NASA should pursue a mission to Mars. What they can't agree on, however, is the best route to get there.

Specifically, the parties are divided over which space rock to use for a waypoint on the Mars mission.

Some Republicans — most famously Newt Gingrich but also a large passel of House lawmakers — see the moon as the most logical waypoint. A lunar base, they say, would allow NASA to test landing technologies and surface operations. It would also allow astronauts to launch humankind's first attempts to utilize extra-Earth resources, including extracting water from the moon's dust.

Obama and NASA's current leadership, however, favor a further foray into the final frontier: capturing, redirecting, and exploring an asteroid. To do so, they want the space agency to invest in solar propulsion engines, technology that is also a prerequisite for a long-distance Mars mission. While the Mars astronauts themselves will travel on a fuel-powered ship, the resupply craft they'll meet along the way will use the slower but more cost-effective solar power.

The battle between the competing visions plays out in annual battles over NASA's budget, where the Obama administration requests funding for its goals, and Republicans — particularly in the GOP-controlled House — push back. And the competition is made all the more intense as the funding pool shrinks: NASA's funding has diminished by more than a billion dollars since 2010 — more than 7 percent of a budget that then totaled $18.7 billion.

What everyone agrees on is that without consensus, neither plan will work. The Mars plan, said a National Research Council report earlier this month, cannot succeed "without a sustained commitment on the part of those who govern the nation — a commitment that does not change direction with succeeding electoral cycles. Those branches of government — executive and legislative — responsible for NASA's funding and guidance are therefore critical enablers of the nation's investment and achievements in human spaceflight."

For now, at least, the unity appears far from likely. Rep. Lamar Smith, a Republican who chairs the House Science Committee, calls the asteroid mission "uninspiring."

Meanwhile, Obama and NASA chief Charles Bolden have accused Congress of whining about NASA's lack of ambition while simultaneously cutting its budget. "We can only do so many things," Bolden said last year.

Obama cited underfunding when he scrapped the Bush-proposed moon mission in 2010, and NASA's budget has declined since. The moon mission was expected to cost around $100 billion ($10 billion of which was already spent when the program closed down). The asteroid plan is estimated at less than $3 billion.

Louis Friedman, a founder of the Planetary Society, says the GOP stance is hypocritical. "I don't think there's an iota of indication [that funding would be raised with a renewed moon focus]. There are people who will talk about that idea."¦ The idea of actually appropriating extra money, we haven't seen anything like that."

He said opposition to the asteroid plan is based on reflexive disagreement with everything Obama proposes, rather than considered, technical reasons. "The industry and NASA are pretty much behind the asteroid redirect," Friedman said.

John Logsdon, a former director of George Washington University's Space Policy Institute, doesn't see it that way. "There are plenty of Democrats not in the White House who think it makes sense to go back to the moon," he said. "[But] everybody at NASA has to salute and say, 'Yes indeed.' "

Logsdon doesn't discount the asteroid plan, but he says the administration was too quick to write off a return to the moon. "If going back to the moon is ruled out, then the [asteroid redirect mission] becomes the best of all possible missions," he said. "The asteroid redirect is an ingenious invention of something that's worth doing now that we're not going to the moon."

So what does NASA stand to gain from each mission? In simple terms, the lunar plan would give astronauts and scientists experience operating on a foreign surface. The asteroid mission would help engineers develop technology for long-range spaceflight.

Republican Rep. Steven Palazzo, who chairs the Space Subcommittee, perhaps best encapsulated the lunar view when he called the moon a "training ground for venturing further into the solar system." Asteroid-hunting, he said, is less a waypoint to Mars than a "detour."

Of course, there's also what Friedman refers to as the "high-ground mentality" — that America shouldn't cede the lunar dominance it's held since 1969. While other nations race to replicate Neil Armstrong's feat, the U.S. should maintain a human presence on the moon, even if it yields no real strategic advantage.

Logsdon, on the other hand, thinks the logic of a moon base actually is strategic — otherwise no one else would be trying to go there. "I frankly don't think anyone would be pushing asteroid redirect if the U.S. embraced a return to the moon," he said. "The rest of the world is focused on going to the moon. We're the only country that's out of sync with that."

America's competitive streak isn't the only reason to visit our planet's closest neighbor. For some, including former NASA Administrator Michael Griffin, the reasoning is more basic: survival. "In the long run a single-planet species will not survive," he said, and the sooner we establish outposts elsewhere the better.

While pro-asteroid folks point to cost comparisons, lunar advocates say their plan would involve a series of missions — rather than a single voyage — so funding arguments are unfair.

Still, the disparity in cost is stark. And supporters of Obama's plan say the technical advantages are just as good.

The astronauts who go to Mars will use rocket power to move their craft toward the Red Planet. But with a mission that could take about three years round-trip, they'll need to restock their supplies along the way.

Years in advance, NASA will shoot off ships loaded with supplies for the Mars-bound (and later Earth-bound) astronauts. Those craft will use solar-electric propulsion, a cheap but slow-moving way to move objects around in space.

That's where the asteroid mission comes in. The first stage of the plan involves a robot ship that will spend about four years traveling to an asteroid. That ship will rely on solar-electric propulsion, a crucial test for the technology and a big step in preparing it for expanded use in the Mars mission.

After the unmanned ship captures the asteroid, it will drag it into lunar orbit, where astronauts can land on and inspect it. Friedman points out that the asteroid's proximity to the moon could support some of the lunar science that moon base advocates have called for — without the "detour" of building infrastructure there (yes, both sides use that word to describe the competing plan).

While politicians argue, NASA is moving forward with the asteroid redirect plan — but without any assurance of support from Congress. And both sides agree that's not likely to change. "What I think will happen is that we'll just muddle along with a plan that tries to do too much with too little money and produces no benefits except government jobs," Logsdon said.

And future NASA budgets, like current ones, are likely to be a "mishmash of various competing interests," Friedman said.