Does alien life need a planet to survive?

What if we removed "terrestrial" from "extraterrestrial"?

Scientists recently explored the intriguing possibility that alien life may not need a planet.

At first glance, planets seem like ideal places to find life.

After all, the only place where life is known to exist is the Earth's surface.

Our planet has a deep gravitational well that holds everything in place and a thick atmosphere that keeps surface temperatures in the right range for liquid water.

We have elements like carbon and oxygen and lots of sunlight shining down on us, providing an essentially limitless source of free energy. yahoonews, the Telegraph reports.

Writing in the journal Astrobiology, the researchers challenge this basic assumption by asking whether it is possible to build an environment that allows life to flourish without a planet.

This idea is not as strange as it seems.

In fact, we already have an example of creatures living in space without planets: astronauts aboard the International Space Station.

But any community of organisms in space must deal with certain challenges.

Putting the challenges together, researchers paint the picture of an organism, or colony of organisms, floating freely in space.

This structure could be up to 100 meters wide and would be contained by a thin, hard and transparent shell.

This shell would stabilize the inner water at the right pressure and temperature and allow it to maintain a greenhouse effect.

While such organisms may or may not exist in the universe, the research has important implications for future human endeavors in space. /Telegraph/