The stone from Mars is a rare and precious resource here on Earth. So far, the only samples we have are pieces of meteorites, ejected from the red planet and traveling through the solar system until they enter the Earth.
A small piece of this priceless thing has just been used fascinatingly: Scientists have founded a small piece of the Martian Black Beauty meteor and used it to grow extremophile microbes.
This not only shows that life could actually exist in real Martian conditions, but provides astrobiologists with new biosigns by which they could look for signs of ancient life in the Martian crust.
“Black beauty is one of the rarest substances on Earth, a unique Martian breccia formed by various pieces of Martian crust (some of which date back 4.42 ± 0.07 billion years) and has ejected millions [of] from the Martian surface, “said astrobiologist Tetyana Milojevic of the University of Vienna in Austria.
“We had to choose a rather bold approach to crushing a few grams of precious Martian rock to create the possible appearance of the earliest and simplest form of life on Mars.”
If ancient life existed on Mars, then of everything on Earth it would most likely resemble an extremophile. These are organisms that live in conditions we once thought were too hostile to support life, such as subsoil, overgrown lakes in Antarctica or volcanic geothermal springs, or the lower crust of the earth, deep below the sea floor.
On ancient Mars, billions of years ago, we are pretty sure that the atmosphere was dense and rich in carbon dioxide. We have a sample of some of the rocks that made up the crust of Mars when the planet was just a baby.
Here on Earth, organisms that can fix carbon dioxide and convert inorganic compounds (like minerals) into energy are known as hemolithotrophs, so the research team considered it a type of organism that may have lived on Mars.
“We can assume that life forms similar to hemolithotrophs existed there in the early years of the red planet,” Milojevic said.
The microbe they chose was Metallosphaera sedula, a thermoacidophilic Archaean found in hot, acidic volcanic springs. This was placed on a Martian mineral in a bioreactor that was carefully heated and gasified with air and carbon dioxide. The team used microscopy to observe cell growth.
They did grow – and the backward land of black beauty allowed scientists to observe how the microbe used and transformed the material to build cells, leaving behind deposits of biominerals. They used scanning transmission electron microscopy to study these deposits down to the atomic scale.
“Grown on the Martian crust, the microbe formed a robust mineral capsule [sic] complex phosphates of iron, manganese and aluminum, “Milojevic said.
“Apart from the mass incrustation of the cell surface, we also noticed the intracellular formation of crystalline deposits of a very complex nature (Fe, Mn oxides, mixed Mn silicates). These are recognizable unique growth characteristics on Noachian Mars breccias mineral springs and a rock chondrite meteorite. “
This could provide some invaluable data in the search for ancient life on Mars. Rover Perseverance, which arrived on the red planet last week, will be looking for just such biosets. Now astrobiologists know what M. sedula crystalline deposits appear, it may be easier for them to identify potentially similar things in Percy’s samples.
The research also emphasizes how important it is to use real Martian samples to conduct such studies, the researchers said. Although we simulated the available Martian regolith, and Martian meteorites are rare, we can get invaluable insight using the real thing.
Part of Perseverance’s mission is to collect samples of Martian rocks that will return to Earth, hopefully in the next decade. Scientists will certainly be looking for dust, but we have no doubt at all that some will be destined for extremophile research.
“Astrobiological research on black beauty and other similar ‘Flowers of the Universe’ can provide invaluable knowledge for analyzing returned samples of Mars to assess their potential biogenicity,” Milojevic said.
The research was published in Communications Earth and environment.