Meteors pepper Mars at a rate up to 10 times more frequent than previously estimated, according to two new research papers that identified the seismic shock waves of these impacts detected by NASA’s now-defunct Mars InSight probe.
The new rate is shocking. According to the findings, between 180 and 260 impacts per year occur on the Red Planet, and these objects can become at least as large as basketballs, leaving eight-meter (26-foot) craters in the ground. Overall, the impact rate is between two and 10 times higher than predicted, depending on the size of the impact. And some of the new impacts detected by InSight were large: For example, one of the studies reports two large impacts, occurring 97 days apart, that were significant enough to each excavate a crater the size of a football field.
“This size impact, we would expect to happen maybe once every two decades, maybe even once in a lifetime, but here we have two of them that are just over 90 days apart,” Ingrid Dauber of Brown University, of which led one of the studies, it is said in a STATEMENT.
Dauber is skeptical that these impacts are mere coincidence and suggests that it is more likely that the impact rate on Mars is generally higher than planetary scientists realized.
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Both studies used the seismometer instrument, SEIS, on InSight (Interior Exploration Using Seismic, Geodetic, and Heat Transport Probes) to detect the impacts. InSight recorded seismic data for four years, during which time it was SEIS active on the surface of Mars (between December 2018 and December 2022). Teasing out the seismic shock wave of an impact from all the other seismic movements inside the Red Planet is not easy, so Dauber’s team compared the seismic data with images of the apparently young craters seen from orbit by NASA. Mars Reconnaissance Orbiter (MRO) to relate oscillations to actual impacts.
From the MRO images, Dauber’s team identified eight new impact craters that had created “marsh earthquakes: detected by SEIS. Six of these craters were in the vicinity of InSight’s landing place on Elysium Planitia. The two largest impacts that were 97 days apart formed craters that are further apart. These two events are the largest new impacts seen to occur on Mars in our history robotic exploration of the Red Planet.
The second study, led by Natalia Wojcicka of Imperial College London, suggests that between 280 and 360 basketball-sized impactors occur each year based on data from SEIS alone. However, the estimated impact rate in each paper, calculated independently of each other using slightly different methods, corroborates each other, which adds to the validity of the results.
Detecting impacts in this way is an important new capability because, previously, planetary scientists could only find new impacts by comparing before and after images of the Martian surface from orbit and seeing if any new craters had appeared. This, as you can imagine, was very inefficient. Seismic data add a new dimension to efforts to measure these impacts. Further, the findings also have ramifications that may permeate our studies of all other solid bodies in our bodies. solar system.
Planetary surfaces do not come with a receipt showing how long ago they formed, or when they were last covered by lava. Instead, scientists must calculate the age of the surface based on the number of craters covering those surfaces; the more craters there are, the older the surface must be. We can see a classic example of this in our moon. The ancient lunar highlands, which are almost as old as the moon itself, are full of craters, while the lunar mare, which is a volcanic plateau up to a billion years younger, has far fewer craters.
However, being able to date planetary surfaces relies on scientists having an accurate handle on impact rates, and new data from Mars suggests that we may not. If the impact rate on Mars is higher than we thought, then some planetary surfaces may be younger than previously determined because they may have accumulated their craters over a shorter period of time.
“By using seismic data to better understand how often meteorites hit Mars and how these impacts change its surface, we can begin to piece together a timeline of the geological history and evolution of the Red Planet,” Wojcicka said in a statement. “You can think of it as a kind of ‘cosmic clock’ to help us date Martian surfaces and, perhaps further down, other planets in the solar system.”
Dauber goes further, saying that not only does the higher degree of impact “carry implications for the age and evolution of [Mars’] surface,” but that “This will require us to rethink some of the models that the scientific community uses to estimate the age of planetary surfaces throughout the solar system.”
Dauber’s team published their findings June 28 in the journal Advances in sciencewhile the findings from Wojcicka’s team were published at the same time in the journal Astronomy of Nature.