Believe it or not, debris from Mars has frequently made its way to Earth after powerful impacts hit the Red Planet’s surface and launch it into space.
Scientists at the University of Alberta have now traced the origins of 200 of these meteorites to five impact craters in two volcanic regions on Mars, known as Tharsis and Elysium.
This meant that these rocks had to have come from a celestial body with recent (in geological terms) volcanic activity, making Mars a likely candidate.
However, proof came when NASA’s Viking landers were able to compare the composition of Mars’ atmosphere with trapped gases found in these rocks.
But knowing exactly where these Martian meteorites came from would allow scientists to better piece together the planet’s geological past.
This can be determined from “shock features” observed in the meteorites—for example, unique mineral changes, impact glass, and special fracture patterns.
From this data, Herd and his colleagues were able to estimate the size of the impact craters that could have launched the meteorites, as well as how deep the rocks were buried before the impact.
“It’s the closest thing we can have to actually going to Mars and picking up a rock.”
Unbelievably, after strong impacts strike the Red Planet’s surface and send debris into space, debris from Mars has regularly found its way to Earth.
In recent history, Mars has experienced at least ten of these meteorite-forming events. These enormous collisions have the power to launch meteorites far enough from the Red Planet to escape its gravitational pull and circle the sun, with some of them falling on Earth in the end.
200 of these meteorites have now been linked by researchers at the University of Alberta to five impact craters in the Tharsis and Elysium volcanic regions of Mars. The university’s meteorite collection curator and professor of science, Chris Herd, said in a statement, “Now, we can group these meteorites by their shared history and then their location on the surface prior to coming to Earth.”.
There are always meteorites falling on Earth; according to NASA, 48,055 tons (44,000 kilograms) of meteorite material fall daily. However, most of the meteorites arrive at the surface as insignificantly small dust particles. Although it can often be challenging to determine their origins, scientists started to have doubts about a group of meteorites in the 1980s that seemed to have been formed by volcanic eruptions and had ages of 1.3 billion years.
This indicated that Mars was a likely candidate because the rocks had to have originated from a celestial body that had experienced recent (in geological terms) volcanic activity. Nevertheless, confirmation arrived when NASA’s Viking rovers compared the elements of these rocks’ trapped gases with the composition of Mars’ atmosphere.
Previously, it was challenging to pinpoint their precise origin on Mars. The team reported in their paper that this challenge resulted from the application of a method known as spectral matching, which compares and identifies the composition of materials by examining the patterns of light that they emit or absorb.
Nevertheless, this technique is limited by variables like large amounts of dust and varying terrain, which can distort spectral signals, particularly on younger terrains like Tharsis and Elysium. But being able to pinpoint the exact source of these Martian meteorites would help researchers better understand the planet’s geological history.
According to Herd, “[It would] enable the recalibration of Mars’ chronology, with implications for the timing, duration, and nature of a wide range of major events through Martian history.”. “I refer to that as the missing piece because it allows us to say, for instance, that an impact event producing craters ranging in size from 10 to 30 kilometers across met the requirements for the meteorite’s ejection. “.”.
The group created a planet resembling Mars by combining high-resolution impact simulations. One of the key developments in this field, according to Herd, is the ability to simulate the ejection process and, from there, calculate the crater size or range of crater sizes that, in the end, might have ejected that specific meteorite or group of meteorites.
Through the output of the model, the team was able to ascertain the “peak shock pressures” associated with the impact events as well as the length of time the rocks were subjected to these pressures. This can be ascertained by looking for “shock features” in the meteorites, such as distinct mineral alterations, impact glass, and particular fracture patterns.
Herd and his associates were able to calculate the depth to which the rocks were buried prior to the impact, as well as the size of the impact craters that may have launched the meteorites, using this data. The researchers compared these depth estimates—which have some degree of uncertainty—with the local geology of potential source craters and the traits and ages of the meteorites to see if they match.
He explained, “[Our modelling approach] allows us to say, of all these potential craters, we can narrow them down to 15 and then from the 15 we can narrow them down even further based on specific meteorite characteristics.”. We might even be able to reconstruct the volcanic stratigraphy, or the geological record, which shows where each rock was before it was blasted away. “.”.
Researchers may be able to learn more about the timing of volcanic eruptions on Mars, the various sources of the planet’s magma, and the rate at which craters developed during the Amazonian period, which began about 3 billion years ago and was characterized by minimal meteorite bombardment.
Herd went on, “If you think about it, it is really amazing.”. It’s the closest thing we have to visiting Mars and taking a rock home. “.
