The dramatic final moments of some microbes’ lives may tell us more about how dangerous the impacts of space rocks were on Earth in the ancient past.
The charred corpses of microorganisms that killed even the moderates asteroid A new study has found that the collision could show the amount of damage caused by a cosmic collision.
A research team examined four craters in Estonia, Poland and Canada that were created thousands of years apart. Despite the geographic distance and amount of time between these different impacts, the team found millimeter to centimeter-sized bits of coal mixed with the material formed during each one, the authors said.
The coal “is made up of organisms that the asteroid killed, grilled and buried,” Anna Luciak, lead author of the Institute of Geosciences at the Polish Academy of Sciences, told Space.com. The discovery of ancient organisms infected with asteroid strikes differed from the coal associated with natural wildfires, which had been the team’s main hypothesis for a while.
She added that coal formed by shock rather than forest fires “is much more homogeneous and indicates a lower temperature of formation.”
She said the effect of the coal found in the craters was similar, but not identical, to that of coal that forms when wood mixes with lava flows. (Pyroclastic flows are formed from an eruption volcanoes.)
The smaller impact craters that Luciak is studying — those up to 656 feet (200 meters) in diameter — form every 200 years or so, she said, thus providing many opportunities to study formation conditions.
But her focus is distinct: “Most people are interested in giant impacts because those are capable of causing planet-wide damage — shrinking dinosaurs is the best, and so far the only example of this type of event,” she said, referring to the asteroid event that led to The extinction of dinosaurs other than birds 66 million years ago.
Pictures: asteroids in deep space
Luciak first found mysterious coal near a small crater in Estonia. I started working during my summer study opportunity as a recent PhD student. He returned a year later to lead a project to discover and study the “paleosoil”. Paleosoil is old soil covered in material that was removed from the crater during its formation, she said.
As it turns out, the team never found the paleosalt. But after three days of digging by hand, a time-consuming necessity due to environmental protection, her team found coal.
“At first, we thought that this coal caused the wildfires that occurred shortly before the impact, and the coal got entangled in this extraterrestrial setting,” she said. “But later I found similar coals in other impact craters, and I started thinking that something wasn’t right with that hypothesis.”
What seemed strange to the team, she said, was why there were so many large wildfires so shortly before the formation of four different impact craters that created geographically distant from each other, and across a timescale of thousands of years.
“It just didn’t make sense, so we decided to further investigate and analyze the properties of the coal pieces that were found mixed within the material ejected from the craters, and compare it to bushfire coal,” she said, when the team discovered that wildfires were not involved at all.
NASA and other entities are constantly searching for extraterrestrial objects, such as comets Or asteroids that may cause a crater a landSurface. So far, scientists have not found any imminent risks to worry about. But Luciac said proper disaster preparedness would benefit from studies like hers.
“This study improves our understanding of the environmental impacts of micro crater formation,” she said. For upcoming collisions, she added, “we will be able to more accurately determine the size and type of evacuation zone needed.”
Large impact events appear relatively recently in recorded history. One of the most famous examples is the Tunguska event, which flattened approximately 770 square miles (2,000 square kilometers) of Siberian forest in 1908.
Recently, in 2014, a small body exploded over a Russian city Chelyabinsk. Thousands of people were injured by glass and other debris, but other than that, the damage was minimal.
Luciak and her team plan to go to another set of small pits in Argentina, in an area called Campo del Cielo, in late September to continue the search.
“We will collect more data and samples, and hopefully we can find more organisms that have been killed by asteroids,” Luciak said. “Campo del Cielo is particularly interesting because there are not only real impact craters – sites where an asteroid literally exploded when it touched Earth – but also penetrating paths.”
Suppression of penetration occurs when an asteroid slows down in the atmosphere as it enters the Earth. Researchers say this formation occurs when it hits the ground at a speed similar to a sniper’s bullet.
“In this case, most of the asteroid survives, and the temperatures and pressures that Earth is exposed to are much lower,” Luciak said. She added that the goal was to conduct a “perfect natural experiment” by comparing craters and trails in the same area.
A study based on the research was published on August 31 in geology journal (Opens in a new tab).