Could Earth Life Survive on a Red Dwarf Planet?

This artist's illustration shows planets orbiting a red dwarf star. Many red dwarfs have planets in their habitable zones, but red dwarf flaring might mean those zones aren't habitable at all. New research explores the idea. Image Credit: NASA

Even though exoplanet science has advanced significantly in the last decade or two, we’re still in an unfortunate situation. Scientists can only make educated guesses about which exoplanets may be habitable. Even the closest exoplanet is four light-years away, and though four is a small integer, the distance is enormous.

That doesn’t stop scientists from trying to piece things together, though.

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Could Life Exist in Molecular Clouds?

This image from the APEX telescope, of part of the Taurus Molecular Cloud, shows a sinuous filament of cosmic dust more than ten light-years long. Could life exist in molecular clouds like this one? Credit: ESO/APEX (MPIfR/ESO/OSO)/A. Hacar et al./Digitized Sky Survey 2. Acknowledgment: Davide De Martin.

Our search for life beyond Earth is still in its infancy. We’re focused on Mars and, to a lesser extent, ocean moons like Jupiter’s Europa and Saturn’s Enceladus. Should we extend our search to cover more unlikely places like molecular clouds?

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There’s a Vast Microbial Ecosystem Underneath the Crater that Wiped Out the Dinosaurs

A three-dimensional cross-section of the hydrothermal system in the Chicxulub impact crater and its seafloor vents. The system has the potential for harboring microbial life. Illustration by Victor O. Leshyk for the Lunar and Planetary Institute.

How did life arise on Earth? How did it survive the Hadean eon, a time when repeated massive impacts excavated craters thousands of kilometres in diameter into the Earth’s surface? Those impacts turned the Earth into a hellish place, where the oceans turned to steam, and the atmosphere was filled with rock vapour. How could any living thing have survived?

Ironically, those same devastating impacts may have created a vast subterranean haven for Earth’s early life. Down amongst all those chambers and pathways, pumped full of mineral-rich water, primitive life found the shelter and the energy needed to keep life on Earth going. And the evidence comes from the most well-known extinction event on Earth: the Chicxulub impact event.

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Seriously, Life Really Does Get Around. It was Found in Rocks Deep Beneath the Seafloor

Map showing the underwater topography (bathymetry) of the ocean floor. Like land terrain, the ocean floor has ridges, valleys, plains and volcanoes. Image Credit: Public Domain, https://commons.wikimedia.org/w/index.php?curid=617528

After a lot of hard work spanning many years, a team of scientists have discovered something surprising. They’ve found abundant bacterial life in tiny cracks in undersea volcanic rock in the Earth’s crust. The bacteria are thriving in clay deposits inside these tiny cracks.

This discovery is generating new excitement around the hope of finding life on Mars.

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Nutrient-Poor and Energy-Starved. How Life Might Survive at the Extremes in the Solar System

Artist impression of a sunset over KELT-9b, where the planet’s atmosphere is hot enough to vaporize heavy metals such as iron and titanium. Credit and ©: Denis Bajram

Our growing understanding of extremophiles here on Earth has opened up new possibilities in astrobiology. Scientists are taking another look at resource-poor worlds that appeared like they could never support life. One team of researchers is studying a nutrient-poor region of Mexico to try to understand how organisms thrive in challenging environments.

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A Microorganism With a Taste for Meteorites Could Help us Understand the Formation of Life on Earth

Credit: University of Vienna

From the study of meteorite fragments that have fallen to Earth, scientists have confirmed that bacteria can not only survive the harsh conditions of space but can transport biological material between planets. Because of how common meteorite impacts were when life emerged on Earth (ca. 4 billion years ago), scientists have been pondering whether they may have delivered the necessary ingredients for life to thrive.

In a recent study, an international team led by astrobiologist Tetyana Milojevic from the University of Vienna examined a specific type of ancient bacteria that are known to thrive on extraterrestrial meteorites. By examining a meteorite that contained traces of this bacteria, the team determined that these bacteria prefer to feed on meteors – a find which could provide insight into how life emerged on Earth.

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Finally! Scientists Find a Place on Earth with Liquid Water But No Life

Hyperacid, hypersaline and hot ponds in the geothermal field of Dallol (Ethiopia). Despite the presence of liquid water, this multi-extreme system does not allow the development of life, according to a new study. The yellow-greenish colour is due to the presence of reduced iron. Image Credit: Puri López-García

In recent years research into extremophiles has captured the interest of astrobiologists. The discovery of lifeforms in some of Earth’s most extreme environments has helped shape our thinking about extraterrestrial life. Life on other worlds may not need the kind of temperate, balanced environment that most life on Earth is adapted to.

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Astronauts Explore Caves on Earth, Learning the Skills They’ll Need for the Moon and Mars

ESA astronauts from five different space agencies are pictured here training in caves in Slovenia, as part of the ESA's CAVES program. Image Credit: ESA–A. Romeo

We’re accustomed to astronauts pulling off their missions without a hitch. They head up to the International Space Station for months at a time and do what they do, then come home. But upcoming missions to the surface of the Moon, and maybe Mars, present a whole new set of challenges.

One way astronauts are preparing for those challenges is by exploring the extreme environment inside caves.

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There’s a Surprising Amount of Life Deep Inside the Earth. Hundreds of Times More Mass than All of Humanity

A nematode (eukaryote) in a biofilm of microorganisms. This unidentified nematode (Poikilolaimus sp.) from Kopanang gold mine in South Africa, lives 1.4 km below the surface. Image courtesy of Gaetan Borgonie (Extreme Life Isyensya, Belgium).
A nematode (eukaryote) in a biofilm of microorganisms. This unidentified nematode (Poikilolaimus sp.) from Kopanang gold mine in South Africa, lives 1.4 km below the surface. Image courtesy of Gaetan Borgonie (Extreme Life Isyensya, Belgium).

Scientists with the Deep Carbon Observatory (DCO) are transforming our understanding of life deep inside the Earth, and maybe on other worlds. Their discoveries suggest that abundant life could exist in the sub-surface of other planets and moons, even where temperatures are extreme, and energy and nutrients are scarce. They’ve also discovered that all of the life hidden in the deep Earth contains hundreds of times more carbon than all of humanity, and that the deep biosphere is almost twice the volume of all Earth’s oceans.

“Existing models of the carbon cycle … are still a work in progress.” – Dr. Mark Lever, DCO Deep Life Community Steering Committee.”

The DCO is not a facility, but a group of over 1,000 scientist from 52 countries, including geologists, chemists, physicists, and biologists. They’re nearing the end of a 10-year project to investigate how the Deep Carbon Cycle affects Earth. 90 % of Earth’s carbon is inside the planet, and the DCO is our first effort to really understand it.

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Life on Mars can Survive for Millions of Years Even Right Near the Surface

Researchers from Lomonosov MSU, Faculty of Soil Science, have studied the resistance microorganisms have against gamma radiation in very low temperatures. Credit: YONHAP/EPA

Mars is not exactly a friendly place for life as we know it. While temperatures at the equator can reach as high as a balmy 35 °C (95 °F) in the summer at midday, the average temperature on the surface is -63 °C (-82 °F), and can reach as low as -143 °C (-226 °F) during winter in the polar regions. Its atmospheric pressure is about one-half of one percent of Earth’s, and the surface is exposed to a considerable amount of radiation.

Until now, no one was certain if microorganisms could survive in this extreme environment. But thanks to a new study by a team of researchers from the Lomonosov Moscow State University (LMSU), we may now be able to place constraints on what kinds of conditions microorganisms can withstand. This study could therefore have significant implications in the hunt for life elsewhere in the Solar System, and maybe even beyond!

The study, titled “100 kGy gamma-affected microbial communities within the ancient Arctic permafrost under simulated Martian conditions“, recently appeared in the scientific journal Extremophiles. The research team, which was led by Vladimir S. Cheptsov of LMSU, included members from the Russian Academy of Sciences, St. Petersburg State Polytechnical University, the Kurchatov Institute and Ural Federal University.

Image taken by the Viking 1 orbiter in June 1976, showing Mars thin atmosphere and dusty, red surface. Credits: NASA/Viking 1

For the sake of their study, the research team hypothesized that temperature and pressure conditions would not be the mitigating factors, but rather radiation. As such, they conducted tests where microbial communities contained within simulated Martian regolith were then irradiated. The simulated regolith consisted of sedimentary rocks that contained permafrost, which were then subjected to low temperature and low pressure conditions.

As Vladimir S. Cheptsov, a post-graduate student at the Lomonosov MSU Department of Soil Biology and a co-author on the paper, explained in a LMSU press statement:

“We have studied the joint impact of a number of physical factors (gamma radiation, low pressure, low temperature) on the microbial communities within ancient Arctic permafrost. We also studied a unique nature-made object—the ancient permafrost that has not melted for about 2 million years. In a nutshell, we have conducted a simulation experiment that covered the conditions of cryo-conservation in Martian regolith. It is also important that in this paper, we studied the effect of high doses (100 kGy) of gamma radiation on prokaryotes’ vitality, while in previous studies no living prokaryotes were ever found after doses higher than 80 kGy.”

To simulate Martian conditions, the team used an original constant climate chamber, which maintained the low temperature and atmospheric pressure. They then exposed the microorganisms to varying levels of gamma radiation. What they found was that the microbial communities showed high resistance to the temperature and pressure conditions in the simulated Martian environment.

Spirit Embedded in Soft Soil on Mars
Image of Martian soils, where the Spirit mission embedded itself. Credit: NASA/JPL

However, after they began irradiating the microbes, they noticed several differences between the irradiated sample and the control sample. Whereas the total count of prokaryotic cells and the number of metabolically active bacterial cells remained consistent with control levels, the number of irradiated bacteria decreased by two orders of magnitude while the number of metabolically active cells of archaea also decreased threefold.

The team also noticed that within the exposed sample of permafrost, there was a high biodiversity of bacteria, and this bacteria underwent a significant structural change after it was irradiated. For instance, populations of actinobacteria like Arthrobacter – a common genus found in soil – were not present in the control samples, but became predominant in the bacterial communities that were exposed.

In short, these results indicated that microorganisms on Mars are more survivable than previously thought. In addition to being able to survive the cold temperatures and low atmospheric pressure, they are also capable of surviving the kinds of radiation conditions that are common on the surface. As Cheptsov explained:

“The results of the study indicate the possibility of prolonged cryo-conservation of viable microorganisms in the Martian regolith. The intensity of ionizing radiation on the surface of Mars is 0.05-0.076 Gy/year and decreases with depth. Taking into account the intensity of radiation in the Mars regolith, the data obtained makes it possible to assume that hypothetical Mars ecosystems could be conserved in an anabiotic state in the surface layer of regolith (protected from UV rays) for at least 1.3 million years, at a depth of two meters for no less than 3.3 million years, and at a depth of five meters for at least 20 million years. The data obtained can also be applied to assess the possibility of detecting viable microorganisms on other objects of the solar system and within small bodies in outer space.”

Future missions could determine the presence of past life on Mars by looking for signs of extreme bacteria. Credit: NASA.

This study was significant for multiple reasons. On the one hand, the authors were able to prove for the first time that prokaryote bacteria can survive radiation does in excess of 80 kGy – something which was previously thought to be impossible. They also demonstrated that despite its tough conditions, microorganisms could still be alive on Mars today, preserved in its permafrost and soil.

The study also demonstrates the importance of considering both extraterrestrial and cosmic factors when considering where and under what conditions living organisms can survive. Last, but not least, this study has done something no previous study has, which is define the limits of radiation resistance for microorganisms on Mars – specifically within regolith and at various depths.

This information will be invaluable for future missions to Mars and other locations in the Solar System, and perhaps even with the study of exoplanets. Knowing the kind of conditions in which life will thrive will help us to determine where to look for signs of it. And when preparing missions to other words, it will also let scientists know what locations to avoid so that contamination of indigenous ecosystems can be prevented.

Further Reading: Lomonsonov Moscow State University, Extremophiles