© Illustration: NASA
Planetary protectors don't just want to keep alien organisms off Earth. They also protect other celestial bodies from earthly stowaways.
There is only one place in the universe that we know that life exists there: our earth. But the search in space has only just begun. And some celestial bodies are known where the conditions could be favorable, or at least once were. For example, Mars: It used to have liquid water and may have produced life. Or large moons in Jupiter and Saturn: Under their thick ice shells there are probably huge oceans that still exist
