Invaders from Earth this week on planetary Radio. Radio. Hi everyone, welcome to Public Radio's travel show that takes you to the final

frontier.

I'm Matt Kaplan.

John Rummel is NASA's planetary protocol. the Final Frontier, I'm Matt Kaplan.

John Rummel is NASA's planetary protection officer.

We'll talk with him about how he and his staff work

to defend our own planet from extraterrestrial infection and more importantly how the space agency

attempts to keep places like Mars and Europa safe from microscopic Earth

tourists. It's a job as big as the solar system.

Later today, Bruce Bats will remind us that there's plenty to see in the night sky,

including a minor meteor shower.

And he'll bring along a new space trivia question that could win you a planetary radio t-shirt.

Think of it as our own multi-world cup.

The big space headlines this week are owned by Space Shuttle Discovery, now docked at the International Space Station, a couple of the

astronauts rode on the low Earth orbit equivalent of a crow's nest.

Their 7.5 hour spacewalk put them not just at the end of the robotic arm but at the

end of a 50 foot boom held by the equally long robotic arm. The

contraption was more stable than expected as the pair practiced the kinds of maneuvers that might be required

to repair a shuttle.

As we finish this week's show, Discovery has been cleared for return to Earth.

We've heard for many of you about our satellite telephone conversation with Stephen

Grasby last week.

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