life

From Mars rock targeting to exoplanet spectra, AI is helping astrobiologists sort possible signs of life from chemistry that looks alive but is not. Here is what it does, what it has not done, and why the hardest step is still human.

In the 1670s, Anton van Leeuwenhoek ground tiny lenses and became the first human to see microorganisms — bacteria, protozoa, and sperm cells. His observations opened the microbial world and laid the groundwork for germ theory.

Bacteria have been on Earth for 3.5 billion years, outnumber all complex life combined, and solve optimization problems better than human computers in some cases. If they evolved intelligence through natural selection, they could become the dominant lifeform on Earth — and humanity might not stand a chance.

Discovering even one living microbe on Mars — or convincing fossil evidence of past Martian life — would be the most consequential scientific finding in history. It would tell us life arises easily where conditions allow, and reshape our entire view of the universe.