Life on Mars? Bacteria Survive Asteroid Impact, Boosting Panspermia Theory

• Something prevents tardigrades from surviving, complicating Mars colonization efforts
• NASA explores Mars and finds it’s not as lifeless as previously thought

The possibility of microbes traveling between planets within asteroids is reigniting scientific debate about the origin of life on Earth. A study published in the scientific journal PNAS Nexus suggests certain microorganisms could survive massive impacts and travel from Mars to our planet.

The research, led by scientists at Johns Hopkins University, supports the theory known as litopanspermia, which posits that life could spread between worlds via rock fragments ejected into space following asteroid collisions. This hypothesis suggests that some of Earth’s earliest microbes may have arrived from another planet.

An Experiment Simulating Asteroid Impacts

To study this possibility, researchers analyzed the behavior of Deinococcus radiodurans, a microorganism renowned for its ability to resist extreme conditions. This microbe can withstand intense radiation, very low temperatures, and extremely dry environments – characteristics similar to those found in space. This research builds on previous work demonstrating the remarkable resilience of tardigrades, often called “water bears,” and expands the scope to include other extremophiles.

The team placed samples of the bacteria between metal plates and fired a projectile with a gas gun to replicate the pressure experienced by a rock ejected after an asteroid impact. The goal was to determine if the microorganisms could survive the most violent moment of interplanetary travel.

Bacteria Capable of Withstanding Extreme Pressures

The tests generated pressures between 1 and 3 gigapascals, far exceeding those found in the deepest parts of Earth’s oceans. For comparison, the pressure in the Mariana Trench, the deepest point on the planet, is around 0.1 gigapascals.

The results surprised the researchers. Almost all of the bacteria survived pressures of 1.4 gigapascals, while nearly 60% remained alive even at 2.4 gigapascals. Although some cells showed damage to their membranes, a significant portion remained active after the impact.

The Possibility of a Martian Origin of Life

“Life could survive being ejected from a planet and traveling to another,” explained engineer K.T. Ramesh, one of the study’s leads, in a statement. Ramesh believes these results force a reevaluation of how life may have originated on Earth and how it could be distributed throughout the solar system.

Lead author Lily Zhao acknowledged the microbe’s resistance exceeded all expectations: “We expected it to be dead at that first pressure. We started shooting faster and faster. We kept trying to kill it, but it was very difficult to finish it off.”

If similar organisms existed on Mars, scientists believe some may have traveled here, opening the door to a surprising idea: that part of life on Earth may have a Martian origin. It’s important to note that fragments of the red planet have been found on Earth, which could only have arrived as debris resulting from asteroid impacts.