Joe Palca

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."

You'd think that someone who is a science correspondent and is as allergic to poison ivy as I am would have heard of urushiol, but no. I didn't recognize the word when I saw it a week or so ago. Now, thanks to my new beat (Joe's Big Idea), I'm allowed to dig a little deeper into stories, and what I learned about urushiol is pretty amazing.

For the past decade, scientists have been toying with the notion of encapsulating medicine in microscopic balls.

These so-called nanospheres could travel inside the body to hard-to-reach places, like the brain or the inside of a tumor. One problem researchers face is how to build these nanospheres, because you'd have to make them out of even smaller nanoparticles.

Tell people you're doing a story about the life spans of Korean eunuchs, the typical reaction is a giggle or a cringe.

But if you can overcome your visceral response to the topic, a study scientists in Korea did is quite interesting, both for what they found, and the way they found it.

Several scientists have shown that there is a link between longevity and reproduction: the greater the fertility, the shorter the life span. This has been fairly well established in nonhuman animal species, but proving it's the case for humans has been tricky.

At this point it's just an interesting hypothesis, but it's possible that understanding cat coloration could help scientists understand resistance to infectious diseases.

It's human nature to hope for positive results after spending months or even years conducting a research study. In well-designed studies, however, scientists identify in advance the criteria for success, so their optimism won't color their conclusions when the study is completed.

A man is not a mollusk, and many men probably think that's a good thing. And it's not just because a mollusk is a squishy invertebrate with a shell. It's also because for at least one species of mollusk, the males do all the heavy lifting when it comes to childcare.

The species of mollusk we're talking about is Solenosteira macrospira, a marine snail about 2 inches long. These snails live off the coast of Baja California, and during the mating season, the beach is awash with male and female snails in connubial bliss.

Scientists in Germany have been able to get enough DNA from a fossilized pinky to produce a high-quality DNA sequence of the pinky's owner.

"It's a really amazing-quality genome," says David Reich of Harvard Medical School in Boston. "It's as good as modern human genome sequences, from a lot of ways of measuring it."

The pinky belonged to a girl who lived tens of thousands of years ago. Scientists aren't sure about the exact age. She is a member of an extinct group of humans called Denisovans. The name comes from Denisova cave in Siberia, where the pinky was found.

You may not be familiar with the name Roger Angel, but if there were ever a scientist with a creative streak a mile wide, it would be he.

Angel is an astronomer. He's famous for developing an entirely new way of making really large, incredibly precise telescope mirrors. But his creativity doesn't stop there. He's now turned his attention to solar power, hoping to use the tricks he learned from capturing distant light from stars to do a more cost-efficient job of capturing light from the Sun.

NPR science correspondent Joe Palca is on a mission this summer to answer the deep, burning questions of summertime. So far he's taught us how to build a campfire, explained the best way to roast a perfect marshmallow and explored the icy mystery of brain freeze.

The Mars rover Curiosity is beginning its fifth day on the red planet, and it's been performing flawlessly from the moment it landed.

That's been especially gratifying for NASA landing engineer Adam Steltzner. Last Friday, while Steltzner was still on pins and needles waiting for the landing to take place, I told the story of Steltzner's decision as a young man to give up his life as a rocker and go for a career in space engineering.

The newsroom at NASA's Jet Propulsion Laboratory is beginning to thin out as the Mars Science Laboratory transitions from an exciting news story, to a long duration — possibly very long duration — exploration of the geologic and environmental history of Mars.

For the reporters still in the newsroom, fatigue is beginning to set in. BBC science correspondent Jonathan Amos has been at it nonstop for 30 hours. I feel a bit guilty for stepping out and getting a few hours sleep.