This is a series

a B. S. I and the world. Behind the Black, 14 years and behind the black and Bob Zimmerman.

I'm John Bachelor. Why 14 years?

Because we needed to get to this point where we're talking about

traveling to another world, not just the moon but to Mars.

That's a trip that's going to require much planning and one piece of planning is what happens to the human condition in extended weightlessness.

And Bob, ever since the 1950s, I've always thought a space station should be spinning,

like Walt Disney said back in the 1950s. Are they going to spin a space station to see

initial weightlessness?

Well, to answer that question, let's talk about the story first, and then I'll answer the question

about whether they're going to spin anything.

Spinning something is a lot of engineering work.

You're going to put a lot of mass in orbit, and that's why no one's done it up to now.

It's more complicated than necessary.

Up to now, everyone who goes into space who lives in weightlessness

in the colloquial times zero gravity and over the years they have discovered

the zero gravity produces significant medical and physical problems.

It causes the spine to stretch back problems, it causes cardiovascular decline, it causes bone density loss.

There are a lot of issues, actually in the muscles, there's a lot of issues like bed rest.

It's not a good thing to sit in a bed and never move.

And basically weightlessness duplicates that situation.

And they've done a lot of studies on six months to year-long missions to try to figure out if exercise

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