NASA

An artist's conception shows astronauts practicing for asteroid exploration on an underwater rock wall.

A NASA team is going underwater this week in the Florida Keys to lay the groundwork for the space agency's first simulated journey to an asteroid.

Sending astronauts to a near-Earth asteroid ranks as one of the top goals for NASA's retooled vision for space exploration. A year ago, President Barack Obama told NASA to gear up to take on such a mission by the year 2025. Up to that time, NASA had been focusing on a return to the moon — which means that the agency had to retool its mission plans. This week's engineering tests, organized by NASA Extreme Environment Mission Operations, or NEEMO, will help NASA get ready to set off for its new target.

"Even experts don't know what the surface of an asteroid is going to be like," NEEMO project manager Bill Todd said today in a news release. "There may be asteroids that we don't even know about that we'll be visiting. So we're figuring out the best way to do that."

The center of this week's operations is the Aquarius Underwater Laboratory near Key Largo, Fla. "We are now trying to understand the nuts and bolts of what it might take to do a spacewalk on an asteroid or on the moons of Mars," NASA astronaut Mike Gernhardt, a member of the NEEMO team, told me today.

The underwater team isn't working from the Aquarius habitat itself. That part of the simulation will come later. Instead, Gernhardt and his NEEMO teammates are jumping off the deck of a ship, heading down to depths of about 60 feet in the Florida Keys National Marine Sanctuary, and practicing their spacewalking skills on an assortment of boulders and rock walls.

"We've created our own mini-asteroid under the water," Gernhardt said.

The aim is to determine which tools and techniques work best for asteroid exploration. NASA has gotten quite familiar with microgravity operations on the International Space Station, and traveling around the moon or Mars doesn't pose all that much of a challenge, gravity-wise. In a sense, making your way around an asteroid combines the worst of both worlds: Most asteroids are so small, it's virtually like working in zero-G. But unlike the space station, there are no built-in handholds or railings. "We have no control over what this asteroid looks like," Gernhardt said.

NASA

In this illustration, astronauts on a Space Exploration Vehicle nestle up against an asteroid and use jetpacks to move around the surface.

NASA

In this artist's conception, an astronaut uses a network of anchors and tethers to move across an asteroid.

Should astronauts hammer in anchors as they make their way across an asteroid's surface? Should they be anchored to a boom stretching out from their spaceship? Or should they use jetpacks to fly freely just a few inches away from the asteroid? Gernhardt and his colleagues will be trying out all three techniques.

"What we're trying to do is fill in the thousand bits of knowledge to bring this from the artist's concepts to reality," he said.

Here are some of the tools the NEEMO team is testing:

• A 27-foot-long, 300-pound boom that could telescope out from a spaceship (or, for the purposes of the simulation, from a piloted submersible) and lock onto a rocky surface.
• A smaller, 20-pound boom that can be anchored at either end, to be used like a handrail to help get around the surface being explored.
• A dual-thruster backpack that can be used underwater to simulate how a jetpack like NASA's current SAFER system would work in outer space.
• Soil-sampling aids, such as a clamshell grabbag that can scoop up samples, and a large plastic bag that can be stretched over rock outcroppings to keep chipped-off samples from floating away.

"Some of the tools that we developed probably won't work very well at all, but as we work down there we'll probably get ideas for better ways to do things," Gernhardt said.

The knowledge gained during this week's tests will be applied to the planning for a full-up mission simulation in October. That's when NASA's "aquanauts" will take up residence in the Aquarius habitat and practice going out in submersibles to explore underwater asteroids. Mission planners will apply the lessons learned in the Florida Keys in other training environments, including NASA's Neutral Buoyancy Laboratory, Air Bearing Floor and virtual-reality lab as well as the International Space Station.

"It's a bittersweet moment as we wind down the shuttle and the space program as we've known it for the past 30 years," Gernhardt said. But he takes some consolation in the fact that the effort being devoted to NEEMO will pay off on the space station and on other worlds, ranging from near-Earth asteroids to the moon and Mars.

"It's exciting to be working with this great team that we've put together here to develop the tools for future space exploration," Gernhardt said. To keep up with this week's activities, check in with this NEEMO webcast as well as the @NASA_NEEMO Twitter account and the NEEMO Facebook page.

More about asteroids and aquanauts:

• Asteroid goal is riskier than the moon
• Gallery: Seven out-of-this-world destinations
• First step for asteroid mission: Pick the right rock
• Undersea lab serves as inner-space station

Connect with the Cosmic Log community by "liking" the log's Facebook page or following @b0yle on Twitter. You can also check out "The Case for Pluto," Alan's book about the controversial dwarf planet and the search for new worlds.