Bacteria could potentially exist on Mars: That’s the conclusion of scientists after discovering that primitive life could survive in saltwater on the surface of the Red Planet.
Specifically, a group of researchers from NASA’s Jet Propulsion Laboratory (California), the Space Science Institute (Colorado), and the University of Mississippi (Kansas) conducted experiments with two salt-tolerant bacteria species on Earth that live in environments mimicking Mars.
These two salt-tolerant bacteria are Halomonas and Marinococcus, collected from a hot water lake in Washington state and from the salt flats of Oklahoma.
To create a Mars-like environment, scientists first created a solution containing salt and magnesium sulfate (MgSO4) and introduced the two bacteria species. They then dried the solution by placing the container in a vacuum chamber with a water-absorbing chemical.
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Image of salt-tolerant bacteria Halomonas. Credit: iStockphoto
After a day, the salts in the dried bacterial culture medium absorbed enough moisture from the container’s humidity to create a saturated liquid, and the researchers observed that some bacteria cells had come back to life.
Although some bacteria had died during the drying and rewetting process, up to 50% of the bacteria miraculously survived in this harsh environment similar to Mars.
This discovery holds significant implications, offering more potential for searching and nurturing life on our neighboring planet.
“They are the first evidence of bacteria that can survive and grow after being dried and rewetted with humidity,” said Mark Schneegurt, a biologist at the University of Mississippi.
A similar process might occur daily on the surface of Mars. Even though Mars is known for its arid conditions, its humidity can rise to 80%, even 100% at night, before dropping significantly during the day.
Professor Mark Schneegurt explained, “It’s possible that sometimes salts can attract enough water to form brines, which could support microbial growth. This discovery provides an opportunity for astronomers to search for life on other icy, arid worlds.”
In addition to its significance for the potential discovery of life on Mars, the study also indicates a greater potential for contaminating Mars and other icy worlds with surviving bacterial populations transported from Earth.
The full findings of the study were presented at the annual meeting of the American Society for Microbiology, held in San Francisco, California from June 20-24, 2019.
“Living Evidence” on Mars
The search for life on other planets has captivated humanity for decades. In the case of Mars, Earth’s neighbor in the Solar System, scientists believe that if life exists on the Red Planet, it could be a “promised land” for future human colonization.
Here are some of the most promising signs of potential life on Mars that science has discovered:
Water
When searching for life on Mars, experts agree that water is the key to life, even though the planet is predominantly rocky and its water may be “locked” in polar ice.
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Credit: NASA/JPL-Caltech
In 2000, scientists discovered evidence of water on Mars for the first time. NASA’s instruments detected flowing Martian sandlines called “recurring slope lineae” (RSL). This discovery led to debates about whether RSL was formed from water flows.
Meteorites
Earth has been struck by 34 Martian meteorites, three of which are believed to carry evidence of a “previous life” on the planet, as reported by Space.com.
In 1996, experts found a meteorite in Antarctica’s South Pole called ALH 84001, which contained organic compounds similar to fossilized bacteria.
However, in 2012, experts concluded that this organic material was formed by volcanic activity rather than life.
Signs of Life
The first close-up images of Mars were taken by NASA’s Mariner 4 spacecraft in 1964. These initial images showed Martian landscapes that could have been formed when the climate was wetter, fueling hopes that the planet might be capable of supporting life.
In 1975, NASA’s Viking program sent unmanned spacecraft to explore Mars, paving the way for future missions.
In early 2018, NASA’s Curiosity rover found signs of past life in an ancient Martian lakebed.
Organic molecules preserved in a 3.5-billion-year-old rock within Gale Crater, believed to have once contained a drying lake the size of Florida’s Lake Okeechobee, suggested that conditions back then may have been favorable for life.
Future missions to Mars have plans to return samples to Earth for more thorough analysis.
Methane
In 2018, Curiosity also confirmed a sharp increase in methane gas in Mars’ atmosphere.
Experts say observations of methane gas provide “one of the most tantalizing cases” for present-day life.