London: It could be decades before man steps foot on Mars, but scientists have warned that if he ever does, he'll bring with him trillions of tiny invaders that pose danger of contaminating the Red planet.
Scientists say a swarming mass of 100 trillion microbes will travel with every astronaut who may land on Mars.
While these microbes have evolved over thousands of years to help humans do everything from digesting their food to keeping bacteria from killing them, there's no telling how they might interact with the Martian environment, the Daily Mail reported.
"We have the responsibility to Mars, I think — even if it's just Martian microbes — not to kill them by the act of detecting them," said Cynthia Phillips of the Search for Extraterrestrial Intelligence Institute.
"If you have human astronauts there, there's no way to sterilise them. They're spewing out thousands of microbes every second. So it's a real problem," Phillips said.
Even if a man on Mars is decades away, at best, space agencies are already thinking about ways to minimise contamination risks.
The Committee on Space Research even established a protocol in 2008, aiming to protect Earth from any contamination from Mars and vise versa.
The plan also advises avoiding gullies, potentially geothermal sites, and any other region where Earth life could survive.
While mechanical pioneers like NASA's Curiosity rover which landed on August 5 this year can be cleaned enough that they only carry no more than 300,000 bacterial spores on any surface that could transfer to the Martian environment, there's no way to get human explorers that clean, the paper said.
The data Curiosity gathers about the Martian terrain coupled with future mechanical explorations could help scientists better understand how sensitive the planet's surface could be to contamination.
The protocols are also being followed by private companies hoping to land men on the Red Planet in the next two decades.
Elon Musk, founder and CEO of the private spaceflight firm SpaceX, has said he hopes fly astronauts to Mars within 15 years and Dutch company Mars One wants to put four people on the planet in 2023 as the first steps towards establishing a permanent colony.
Under the 1967 Outer Space Treaty, countries can be held responsible for interplanetary activities of private businesses within their borders, and could be taken to international court on charges of contaminating another
"It's the environmentally responsible thing to do," said Cassie Conley, NASA's planetary protection officer.
"If you want to be a good citizen of the solar system, you do the planetary protection requirements, just like you pick up the litter and you don't spread your pollution all over the countryside," Conley said.