This is planetary radio.

Hi everyone, I'm Matt Kaplan.

Who says science rules?

Bill Nye the science guy, that's who.

And because he does, so do millions of other people across America.

But did you know Bill is making scientific contributions to our exploration of Mars?

You'll hear about it in a minute.

And later today we'll all meet Sandy Moon Dust, the other LEGO Astrobot.

She's about to leave for the Red Planet on the second Mars Exploration

rover.

Back with Bill Nye, right after Emily tells us

how we know those meteorites from Mars are the genuine item.

Hi, I'm Emily Loch Duwala with questions and answers.

A listener asked, news reports about meteorites from Mars claimed to show that Mars had a warmer, wetter

environment in the past or even that it had life. But how does scientists know that the meteorites came from Mars? Chemical analysis of meteorites found on Earth can reveal their Martian origin. We have direct observations of the chemical composition of the Martian atmosphere from the Viking Landers.

These observations include measurements of the amounts of different isotopes of hydrogen and oxygen.

Because Mars has lost much of its original atmosphere to space,

heavy isotopes of hydrogen and oxygen are more concentrated in Mars's atmosphere than Earth's

atmosphere. When we measure the isotopes of hydrogen and oxygen from water and gas pockets trapped deep within the meteorites, the chemical signature is very similar to that observed by the Viking spacecraft on Mars.

What else can we learn from Mars meteorites?

Stay tuned to planetary radio to find out.

So Bill, you know, they sometimes stand up and say, now here's somebody who needs no

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