What the Deep Ocean Teaches Us About Life on Other Worlds

The best place to practice looking for life on other worlds may be the bottom of our own ocean. The conditions humans find comfortable are probably extremely rare beyond Earth. But the far wider range of conditions where microbes live on Earth is more likely to exist on other planets and moons — and some parts of our ocean may resemble places elsewhere in the solar system.

Tubeworms growing where hot vent fluid meets cold seawater on the ocean floor. Chemosynthetic bacteria living inside them draw energy from chemicals in the hot water of hydrothermal vents. Credit: NOAA.

Lovers of extremes

On Earth, life turns up everywhere from the coldest arctic ice to extremely hot hydrothermal systems on the seafloor. Microbes also live in very acidic, very salty and very alkaline conditions. These microbes are called extremophiles — "lovers of extremes" — and they widen our idea of where life can exist.

An ocean under the ice

Jupiter's moon Europa is covered entirely by ice. But the tidal energy that giant Jupiter exerts on it is so strong that a global ocean probably lies beneath the ice — one that could be 10 times as deep as the ocean on Earth. Many scientists think hydrothermal vents may exist at the bottom of that ocean.

Why that matters

That possibility is exciting because, in Earth's oceans, hydrothermal vent systems are full of microbes. Understanding the extreme life we have here could help scientists recognize environments on other moons and planets where life might exist.

Sources

Based on "What can the ocean teach us about life on other planets?" from NOAA's National Ocean Service, a work of the United States government in the public domain.