Did We Bring Life to Mars? Bacterial Organisms Found on Curiosity Rover
Researchers have long been trying to find life on Mars, but we may have cheated in that quest by unnaturally spreading life to Mars that originated on Earth. A study for the American Society for Microbiology found that 377 strains of bacteria survived the sterilization process that the Curiosity rover underwent before traveling to Mars.
It is unknown whether the bacteria spread to the surface of Mars, although it is unlikely that the bacteria could reproduce or thrive since the Curiosity wasn't exploring water or ice-covered regions. Still, researchers are concerned about the risk of contamination in future efforts to study Martian environments. Stephanie Smith of The University of Idaho in Moscow and lead author of the study wrote, "Knowing if microorganisms survive in conditions simulating those on the Martian surface is paramount to addressing whether these microorganisms could pose a risk to future challenging planetary protection missions."
According to the United Nations Outer Space Treaty of 1966, nation states are liable for any damage caused to other planets by their studies, and it specifically states that nations must avoid harmful contamination of other planets.
The specific limits to the number of spores that can exist on a manmade space object are stricter for planets that could potentially support life, such as Mars and Europa. The odds of contamination need to be less than 1 in 10,000. For the Curiosity rover specifically, this means that 300,000 spores were allowed on the surface of the rover, and the current spore count totals less than 200,000. According to NASA engineer Laura Newlin, this number of spores could fit on the head of a pin. However, the finding that certain strains of bacteria may be able to survive conditions on Mars's surface may lead to a reevaluation of the current guidelines.
Scientists now believe that the fact that the microbes endured in spite of the researchers simulating many of the conditions on Mars has even greater implications. The bacteria survived near-freezing temperatures and extreme exposure to ultra-C radiation, which is considered to be the most dangerous type of radiation. While it is still unknown whether these organisms could actually survive on Mars, the results of this study certainly appear to support that notion.
This research somewhat reinforces the findings of another study at The University of Arkansas Fayetteville which claimed that microorganisms called methanogens (classified in the domain archaea, as opposed to bacteria), the oldest organisms on Earth, would be ideal candidates for surviving the harsh conditions on Mars. Since the temperatures of Mars vary widely, organisms such as methanogens that naturally undergo freeze-thaw cycles could potentially endure the Martian environment.