The panspermia hypothesis proposes that new planets are colonized by microscopic life forms trapped in debris and blasted into space by collisions between comets, asteroids, or other small space bodies. Microbes such as bacteria or other organic compounds could become active and begin to colonize their new environment—if they could survive the effects of space. A new study has found that certain bacteria can survive a yearlong exposure to the extremes of space, suggesting that the interplanetary migration of microbes may be possible.
A research team, led by Akihiko Yamagishi of Tokyo University of Pharmacy and Life Sciences in Japan, developed specially-designed panels to expose the bacteria Deinococcus aetherius to the extreme temperature fluctuations, ionizing radiation, and solar radiation of space. The wells in three such panels were filled with varying densities of dehydrated D. aetherius cells. The panels were then sent to the Exposure Facility of the Japan Experimental Module on the International Space Station (ISS), as part of the Tanpopo space mission.
Once onboard the ISS, the panels were placed on a mechanism that used robotic arms to transfer them outside the ISS. During the experiment, sensors attached to the panels measured and recorded temperature, ionizing radiation, and solar radiation through 382 days of exposure. One panel was then shipped back to Earth in a space capsule, and the contents of the wells were incubated and then counted to determine how many bacterial colonies survived the conditions of space.
The cells that were more densely placed on the exposure panels survived better than those that were placed less densely. The researchers suggest that only the first layers of cells in the more densely filled wells died, protecting the rest of the cells below and allowing them to survive. Thus, under certain conditions, D. aetherius is able to survive the extreme space environment.
The researchers are further investigating how other factors, such as impact from space debris, may have affected the bacteria’s survival rates. Additionally, two more panels remain in space, to be recalled for study at later dates after even longer space exposures. (Astrobiology)