18 Worlds could be contaminated by spacecraft

So far, scientists have found no evidence that life exists elsewhere in the Solar System. But as we learn more about how ‘extreme’ microbes live in underwater volcanic vents or frozen environments, more possibilities open up for where they could live on other planets.

Microbial life is now considered likely enough on Mars that scientists take special precautions to sterilise spacecraft headed to the planet. NASA chose to crash its Galileo spacecraft into Jupiter rather than risk it contaminating the potentially habitable oceans of Europa.