Life’s Interplanetary Hitchhiking: Microbes Could Survive Asteroid Impacts and Travel Between Planets

New research suggests that remarkably resilient microorganisms could survive the extreme conditions of an asteroid impact and subsequent journey through space, potentially traveling between planets like Mars and Earth. This discovery, centered around the bacterium Deinococcus radiodurans, has significant implications for our understanding of the origins of life and planetary protection protocols for space missions.

The Toughest Bacterium Known to Science

Deinococcus radiodurans, nicknamed “Conan the Bacterium,” is renowned for its ability to withstand environmental stressors that would obliterate most other life forms. It can endure extreme cold, intense radiation, harsh chemicals, and profound dehydration [1]. Its resilience is thought to stem from adaptations to its natural habitat – the high, dry, and sun-scorched deserts of northern Chile.

Simulating Asteroid Impacts

Researchers at Johns Hopkins University conducted experiments to determine if D. Radiodurans could survive the immense shocks and mechanical stresses associated with asteroid strikes on Mars [2]. They simulated these impacts by firing a projectile from a gas gun at colonies of the bacteria sandwiched between two steel plates, generating pressures up to 3 Gigapascals – more than ten times the pressure found at the bottom of the Mariana Trench [4].

Survival Against the Odds

The results were striking. D. Radiodurans survived nearly every test at 1.4 Gigapascals of pressure, and 60% survived at 2.4 Gigapascals [1]. While some cells showed ruptured membranes and internal damage at the higher pressures, the bacteria proved remarkably difficult to kill. In fact, the steel apparatus itself failed before the bacteria did [1].

Lithopanspermia: Life Traveling Between Planets

This research lends support to the theory of lithopanspermia – the idea that life can travel between planets aboard impact debris [3]. Asteroid impacts are common throughout the solar system, and fragments ejected from these events could potentially land on other worlds, carrying microorganisms with them. Martian meteorites have already been discovered on Earth, demonstrating that material can be exchanged between planets.

Implications for Planetary Protection

The findings have key implications for planetary protection protocols. Space mission protocols currently aim to prevent the contamination of other planets with Earth life, and to prevent the release of potential extraterrestrial life on Earth [1]. Given the demonstrated resilience of D. Radiodurans, and the possibility of life surviving interplanetary travel, these policies may need to be reassessed, particularly concerning destinations like Mars’ moons, Phobos and Deimos [2].

Future Research

Researchers plan to investigate whether repeated asteroid impacts could lead to even hardier bacterial populations, and whether other organisms, such as fungi, can also survive these extreme conditions [1]. This ongoing research will continue to refine our understanding of the potential for life to exist – and travel – beyond Earth.