The following is an encore presentation of Everything Everywhere Daily.

On July 20, 1976, Viking 1 became the first robotic lander to land on Mars.

On September 3rd, its sister Viking 2 followed suit.

Both of them carried experiments to test for biology on Mars,

something which no subsequent Mars Lander has since replicated.

The results from these chemical experiments have divided researchers for decades and have been

the cause of one of the greatest debates in planetary science.

Learn more about if we have already found evidence of life on Mars on this episode of

Everything Everywhere Daily. The If you remember back to my previous episode on the history of Mars exploration,

sending probes to Mars has been really hit or miss.

It turns out that sending a robot to land on the surface of another planet is really, really hard.

That is why it was such a big deal when the Viking One Lander managed to safely touch down on the surface of Mars on July 20, 1976.

It was the first time humans had safely landed on the Red Planet.

A few months later, an identical Ler Viking II also safely reached Mars.

The Viking Landers were rather large for planetary probes.

Each was about the size of a jeep.

Unlike current probes that are rovers or even have a small helicopter, the Viking Landers didn't go anywhere.

Their primary jobs were to take photos, gather meteorological and geological data,

and provide chemical and biological data and

experiments on the Martian soil.

That last part, the chemical and biological experiments

is what this episode is all about.

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