Scientists suggest life on earth could have spread to other planetary bodies in the solar system.

Two groups of researchers have used models to demonstrate the possibility, Nature reports. The researchers talked about their work this week at the Lunar and Planetary Science Conference in League City, Texas.

"Once one planet comes down with life, they all get it," said NASA scientist Jeff Moore, comparing the spread of life to the spread of the common cold.

Two groups of researchers have used computer simulations and models to test the theory. One found that the Jovian moon Europa and Titan, one of Saturn's moons, would receive bits of earth thrown up by the impact of a large meteor -- with up to 100 pieces landing during a 5 million year period -- while the other showed that a few bacteria would survive the meteor strike.

Any earth fragments that head for Europa would be going at such speed because of Jupiter's gravity that they would be sterilized before landing. But bacteria might get to Titan.

The next question is whether they could survive on a moon where the temperature is minus 170 degrees Celsius.

Copyright 2006 by United Press International