It is unclear whether these bacteria can survive in Titan's icy atmosphere
22.3.2006
By: Avi Blizovsky
Rocks from Earth blown into space when asteroids hit Earth could have brought life to Saturn's moon Titan. That's what scientists say. Bacteria from Earth in these meteorites could have seeded the world full of organic matter with life.
The scientists believe that the impact that wiped out the dinosaurs could have thrown enough material into space, some of which reached as far as Saturn's moon Titan. The details were revealed at an important scientific conference in Houston.
Panspermia theory holds that life on planets like Earth and Mars was seeded from space, they may have hitched a ride on meteorites and comets.
In order for terrestrial rocks containing life to escape the gravity of the Earth and its atmosphere and reach space, a strong impact by an asteroid with a diameter of at least 10 to 50 kilometers is necessary. Only a few of the bodies that hit the Earth meet the requirement.
A journey of a million years
One of these bodies is the asteroid that hit 65 million years ago, which left a crater gap estimated at 160-240 km in diameter in the area now called the Yucatan Peninsula in Mexico.
Brett Gladman, from the University of British Columbia in Vancouver and his colleagues calculated that about 600 million particles from such an impact could have escaped the Earth and orbited the Sun. Some of them may have gained such a speed of littering that would bring them to the vicinity of Jupiter and Saturn in about a million years.
The scientists used a computer model, in which they mapped the behavior of these particles once they are in orbit. From this they calculated the expected number that would hit certain moons of Jupiter and Saturn.
The main targets they chose, Titan and Europa are considered interesting to astrobiologists - who study the origin of life on Earth as well as the consequences of settling other planetary bodies.
Titan is rich in organic materials that provide a potential energy source for primitive life forms. Europa is a moon that contains an ocean of liquid water under a thick mantle of ice.
quick hit
Dr. Gladman's team calculated that up to 20 terrestrial rocks from such a large impact would reach Titan. These rocks can hit Titan's upper atmosphere at a speed of 10-15 kilometers per second. At this speed, the descent down to the surface can be soft enough for bacteria to survive the journey.
But the more important news is for Europe. Due to its greater proximity to Earth, about a hundred terrestrial rocks could have hit Europa, but Jupiter's gravity might accelerate their speed so that they could hit at an average speed of 25 kilometers per second, and some of them even at a speed of 40 kilometers per second. According to Dr. Gladman, some of the Tsavat scientists calculated and found that the chances of the amino acids reaching the surface of the moon are not high. "You would be extremely lucky if you were a bacterium that moved through the universe for a million years and then died upon impact on the surface of Europa," commented Dr. Gladman.
A presentation in which the details of the research were published in a lecture held at the Scientific Conference on Moons and Planets in Houston, Texas.
Yedan Saturn
