February is a blockbuster month for Mars missions. The United Arab Emirates and China have both arrived successfully in Martian orbit this week, and NASA is due to land its Perseverance rover on the red planet next Thursday. 

All of these missions are, to some degree, tasked with assessing whether Mars might have hosted life in its distant past, billions of years ago. This question is not only crucial to our understanding of Mars’ habitability, it also has implications for life on Earth: many scientists think that life may have started on Mars first, only to spread to Earth, through a process called panspermia.

Amir Siraj, a student studying astrophysics at Harvard University, has co-authored several papers about panspermia, which he called a “very interesting theory.” 

“We know that exchange between the Earth and Mars does exist,” Siraj said in a recent VICE News interview. “We see Martian meteorites and there is absolutely reason for us to think that if there was biology on Mars at some point, then it could have been brought to Earth.” 

“It’s very difficult to ascertain the origins of life on Earth,” he added, “but the idea that it could have come from Mars is far from a wild one.”

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