14 DAY TRIAL // Life on Earth can get the most diverse and weirdest forms, but in the end the basics of its functioning are the same. But life can be even weirder and function on different principles on remote planets and moons, as signaled by a new report issued by the National Academy of Sciences (NAS).
In an alien world, the organisms could thrive in oceans of liquid methane instead of water and they could use chemical energy got from minerals or hydrochloric acid rather than solar one.
"These possibilities could revolutionize future space missions in search of life elsewhere in the solar system," signals the report.
Researchers should consider a more diverse list of traits that define life, as most alien organisms would thrive where Earth organisms couldn't. The report points rather to Saturn's moon Titan as a main candidate for life in the Sun System than Mars, despite its watery past, as that moon has seas of liquid methane and ethane.
"It's a carbon world, so there's plenty of different kinds of carbon compounds there, and the possibility is that there may be the carbon compounds that make up life," said lead author John Baross, an oceanographer at Seattle's University of Washington.
"We don't want to not recognize a life form because it doesn't exactly resemble Earth life," Baross said.
Earth life displays certain traits and needs: water, carbon-based metabolism, an energy source (chemical or light) and the ability to evolve and these have been also applied when looking for alien life.
"But advances in biology and biochemistry in the last decade show that the basic requirements for life may not be so concrete," said Baross.
"The Viking lander missions to Mars in the 1970s were controversial, because although they did not find life, they only looked for Earthlike life. Let's be a little more broad-minded. Let's not just look for life as we know it. The only problem is it's very difficult to look for life as you don't know it, because you don't know how to look for it," said Seth Shostak, a senior astronomer at the SETI Institute in Mountain View, California, dedicated to the search for alien life, but not involved in the report.
Lab tests have recently shown that the DNA of Earth organisms can be changed and the organisms keep on encoding the new genetic information.
This points that "a different life-form doesn't necessarily have to have exactly the same chemistry that Earth life has. Even weirder life may tap into different sources of energy than the sun, which most Earth organisms depend upon. Perhaps most intriguing is the possibility that extraterrestrial life could thrive on a solvent other than water, such as the liquid methane and ethane on Titan. Could a carbon-based life-form survive and live in that? That's pretty much an unknown to Earth life." said Barros.
"The hunt for weird life on other planets and moons begins with studying life on Earth. For example, one of the biggest unanswered questions about Earth life is how it originated," he added.
Earth life in extreme environments like arid deserts, high-altitude lakes, or boiling deep-sea vents could offer some clues.
"The lessons learned from Earth's weird life can then guide the search for even weirder life elsewhere in the universe," the researchers wrote.