A big bang in Tunguska exactly 100 years ago this week on planetary radio. Hi everyone,

welcome to Public Radio's travel show that takes you to the final frontier.

I'm Matt Kaplan.

June 30, 1908. It must have seemed like any other

day in that thickly forested section of Siberia. Then it happened. An explosion as powerful

as a 3 to 5 megaton thermonuclear bomb.

Thousands of square kilometers were flattened in an instant.

Now we know it was the airburst of a meteor, even though no fragments have ever been found.

Bill Hartman hasn't just thought about this, he has painted it.

We'll explore the Tunguska event with the famed planetary scientist on today's show.

And stay tuned to hear what's up from Bruce Betts featuring the winner of our Random Space Fact recording contest.

You're going to love it.

First, though, let's get another update from the Martian Arctic Circle

courtesy of Emily Lochuwala. Emily I was reading your account on the blog the

latest from Phoenix and and I think we've got Phoenix on the rocks.

Yeah, we do, Matt.

The results this week that were announced were from the wet chemistry lab, part of the Mecca

experiment.

And this is a unique experiment. They brought a little ice cube of distilled water with them from Earth.

They melt it, put it in a little beaker, and then bring a tiny sample of Martian soil and dump it into the beaker, stir it up and see what goes into solution in the water. it opposite of acid, but it's not very alkaline. It's not too bad, pH of 8 or 9, which would be

compatible with growing asparagus turnips or green beans, they remarked. And they found a few

metal anions and cat ions in this soil and they found that the soil is only very slightly

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