Where and how can we search for life?

We search for life in places that offer the three most common necessities for it: water, energy and carbon. All life as we know it is based on carbon, needs water and directly or indirectly derives energy from the Sun. So we look in places that have these three necessities.


There are three such places in our solar system: Mars, Jupiter’s moon Europa and Saturn’s moon Titan. The surface of Europa appears to consist of water covered by a thick layer of ice. Great waves break the ice, and a red liquid seeps out of the cracks. Some believe that the red colour indicates an enormous colony of bacteria, while geologists believe that it may indicate mineral deposits.

Titan is colder yet, and almost everything is frozen. But occasionally comets hit Titan, and their impacts create craters of melted ice. The water in the craters can be liquid for thousands of years, so life may have taken root there.

Scientists examine these locations by telescope, but telescopes are not powerful enough to see microorganisms. So we are sending space probes to these places to take samples and photographs. Now there are several unmanned missions on the way to Mars, and the Cassini probe is on its way to Saturn. As yet, no mission has been planned to Europa.

We’re also searching for life outside our own solar system, by other means and by seeking other forms of life. We’re searching for intelligent life that hopefully is sending radio signals that we can identify.