NASA launches its new robotic mission to Mars. The rover, Perseverance, will land in a 50 kilometre wide crater which looks like it was filled by a lake about 4 billion years ago - the time when life on Earth was getting started. Mission scientist Melissa Rice explains why this is one of the most promising places on Mars to continue the search for past life on the red planet.

Japanese and US scientists have revived microbes that have been buried at the bottom of the Pacific Ocean for 100 million years. Sampled from compacted mud 70 metres below the seafloor and beneath 6 kilometre of water, Yuki Morono and Steve D'Hondt admit they struggle to understand how the bacteria have survived for so long.

Science in Action celebrates the little unknown oceanographer Marie Tharp who in the late 1950s discovered the mid-Atlantic ridge which helped to launch the plate tectonics revolution in earth sciences. It would be Tharp's 100th birthday this week.

New research this week suggests that coronaviruses capable of infecting humans have been in bats for 40 to 70 years, and that there may be numerous and as yet undetected viruses like the Covid-19 virus in bat populations with the potential to cause future pandemics. Their message is that we should be sampling and testing wild bat colonies much more extensively than currently. Their findings provide further evidence against the unfounded claim that the Covid-19 virus originated from the Wuhan Institute of Virology in China. Roland Pease talks to Dr Maciej Boni at Pennsylvania State University.

Listener Avalon from Australia wants to know why people use conspiracy theories to explain shocking events. Are we more likely to believe conspiracy theories in times of adversity? What purpose do conspiracy theories serve in society?

Marnie Chesterton speaks to the scientists to explain their popularity, even in the face of seemingly irrefutable evidence.

(Image: NASA's Perseverance Mars rover. Credit: Illustration provided by Jet Propulsion Laboratory in Pasadena, California. NASA/JPL-Caltech/Handout via REUTERS)