Ammonia on Mars could mean life BBC

Ammonia may have been found in Mars’ atmosphere which some scientists say could indicate life on the Red Planet. Researchers say its spectral signature has been tentatively detected by sensors on board the European Space Agency’s orbiting Mars Express craft. Ammonia survives for only a short time in the Martian atmosphere so it must be getting constantly replenished. There are two possible sources: either active volcanoes, none of which have been found yet on Mars, or microbes.