How Did the Successful Robotic Missions Affect Life on Mars?

The key moment happened in 19 76 when the us. Probes, viking one and viking two, landed on mars. Both probes were specially designed to search for life. One of these tests was developed by a man named gilbert levin. Gill levin's experiment returned positive results. It behaved as predicted when they did the test again. And they announced that they had found life on mars. Then they decided to change the criteria and said they hadn't found life after all. That sparked a big controversy. We'll talk about next week.