This is planetary radio. Hello again everyone. I'm Matt Kaplan. The history of robotic planetary and

lunar exploration is short, barely 40 years.

Yet those decades have been plenty of time to generate incredible stories of discovery.

Our guest today was an observer and participant in almost all of this history.

Yuri Vanderwold will share some of his first-hand stories in a special extended conversation, which you'll hear only here on the website.

Bruce is back from Hawaii with what's up and a maritime trivia question.

First though Emily tells us about two protective barriers all life on Earth can be thankful for.

I'll be back in just a minute. Hi, I'm Emily Lockwala with questions and answers. A listener observed that Earth's magnetic field maintains the Van Allen belt and shields Earth life from dangerous solar radiation.

But I know that the magnetic field sometimes collapses and reverses itself.

What happens to life on Earth if the magnetic field collapses?

The short answer is that Earth's atmosphere is far more important than its magnetic field

in shielding the biosphere from potentially significant radiation from the Sun and cosmic rays.

Most of the Sun's radiation, which includes gamma rays, x-rays, UV invisible light, infrared, and radio emissions are electromagnetic waves which are not affected by Earth's magnetic field.

Most of the most hazardous solar radiation is absorbed by the upper atmosphere.

In addition to this radiation, the sun also emits a flow of low energy ionized

gas called the solar wind, along with sporadic bursts of high energy charged particles.

Could these particles harm life on Earth in the absence of a magnetic field?

Stay tuned to planetary radio to find out. The exploration of the solar system with planetary probes and the like may seem like it's been going on for a long long time

but it really hasn't been that long. In fact the pioneers in that work in that research

most of them are still with us and of course they in that

research, most of them are still with us.

And of course, they include scientists and engineers,

...