NASA wants mission to bring Martian rocks to Earth

If NASA's exploration of Mars were summed up in a bumper sticker, it would read: "Follow the water."

Well, they've found the water — ice was discovered by the Phoenix lander in 2008.

Now what?

It's time to search again for signs of life, scientists say, something they haven't done since 1976. This time, they want to bring Martian rock and soil samples back to Earth. Here, they could be analyzed for fossilized traces of alien bacteria, or chemical or biological clues that could only be explained by something that was alive.

Such a venture as now outlined would be a three-part act, cost as much as $10 billion and take several years to complete. NASA can't afford it on its own so it recently joined the European Space Agency to map out a shared project.

Space policy experts think the timing is right despite the risks and hefty price tag.

"We're about out of things to do on Mars other than a sample return," said George Washington University space scholar John Logsdon. "It is an extremely expensive undertaking, probably the most expensive robotic mission to Mars and clearly the most complex."

The idea of bringing Mars samples to Earth for study has been floated for the past 25 years without going anywhere due to cost and engineering concerns. Many believe it's still the best way to answer whether life ever arose on Mars.

At a town hall meeting near Los Angeles this spring, NASA told Mars researchers the next effort would be done in phases. It would be attempted before the mid-2030s, the timetable for astronauts to land on Mars as proposed by President Barack Obama.

As currently envisioned, a pair of rovers would launch in 2018 to a spot where water once flowed. One would drill below the surface; the other would collect rocks and dirt and seal them in containers.

Several years later, some cosmic choreography would be used to get the bounty back to Earth. One spacecraft would touch down to collect the samples and launch them into orbit around Mars where a rendezvousing spacecraft would capture the bounty and return it to Earth.

Even if those challenging tag-team missions went as planned, the first Mars samples would not be returned until the 2020s.