Joe Palca

The director of NASA's Jet Propulsion Laboratory said last week that preliminary data showed the possibility that the agency's Mars Science Laboratory – the six-wheeled rover that landed on Mars in August — had found signs of carbon-containing molecules.

Mercury is not the first planet to come to mind if you were searching for ice in the solar system. After all, the surface temperature across most of the planet is hot enough to melt lead.

But at the poles on Mercury it's a different story. Almost no sun reaches the poles, and as a result, temperatures can drop to less than -100 degrees Fahrenheit. Now, three papers in the journal Science suggest there really is ice at the bottom of craters near the poles on Mercury.

Scientists working on NASA's six-wheeled rover on Mars have a problem. But it's a good problem.

They have some exciting new results from one of the rover's instruments. On the one hand, they'd like to tell everybody what they found, but on the other, they have to wait because they want to make sure their results are not just some fluke or error in their instrument.

Every time a storm brings flooding to a large metropolitan area, there are calls to improve the levee systems that are designed to prevent flooding.

But there's a major problem with doing that. "We don't know where all of our levees are," says Samantha Medlock with the Association of State Floodplain Managers.

Residents of Moonachie and Little Ferry, N.J., are beginning to clear the damage after their communities were inundated by floodwaters. The flooding occurred when a system of levees and berms was unable to control the storm surge pushed ashore by Superstorm Sandy.

Geologist Jeffrey Mount of the University of California, Davis, isn't surprised. "There really are only two kinds of levees," he says, "those that have failed, and those that will fail."