Is there Life on Another World in Our Solar System?

       Life on Earth takes a bewildering, almost unimaginable range of forms. Some seem so different, it’s hard to believe they didn’t evolve on an alien planet. One resource all life on our planet requires to survive is water. Most scientists, therefore, believe that if we are to find life elsewhere, we must find a planet or moon with sufficient liquid water.

As it turns out, water is not scarce in the universe. It is a compound of atoms of hydrogen and oxygen, which are the first and third most abundant elements in the universe, making water, H2O, one of the most abundant substances in the universe.

The problem is finding water in a liquid form. On many alien planets we have discovered, the temperature is so hot that the water is all in vapor form. Or it might be underground and, perhaps, too salty to support life as we know it.

One example is Saturn’s moon Enceladus. NASA’s Cassini mission discovered jets of water spewing off the tiny moon. That really surprised scientists. They thought that moon was so small that any water would be frozen solid. But the action of Saturn’s gravity on the moon warms it up enough that Enceladus possesses a global, underground liquid water ocean. Originally, scientists assumed it might be far too salty to support life.

Water Jets spewing into space from the South Pole region of Saturn's moon Enceladus. 

Credit NASA-JPL-Space Sciences Institute

A group of researchers at MIT decided to work on a project to determine if that water could support life. They discovered that the thickness of the polar ice shell is dependent on the water’s salinity. Their analysis of data showed that the ice on the moon is thinner at the poles than at the equator. They determined that the salinity of Enceladus’ ocean is lower than that of Earth’s oceans. And Earth’s oceans contain lots of life.

Cut-away view of the ocean on Enceladus. 

Credit NASA-JPL-CalTech-Southwest Research Institute

That doesn’t automatically mean that Enceladus has life in its oceans. Other factors also determine habitability. But at least the water on the moon can support life. That dramatically increases the odds of extraterrestrial life there.

 

Each month, I write an astronomy-related column article for the Oklahoman newspaper. On the following day, I post that same column to my blog page.

 This is reprinted by permission from the Oklahoman and www.Oklahoman.com.