NASA’s Insight lander has detected several meteorite impacts with its seismometer on Mars. The research team responsible for this has now announced this. He observed the first impact of three fragments on September 5, 2021. The Mars Reconnaissance Orbiter later discovered three of the resulting craters. A precise analysis of the measurement data then found three more impacts in May 2020, February 2021 and August 2021, from which Insight recorded seismic waves. They are the first seismic and acoustic waves ever discovered on another celestial body. It is puzzling why Insight has not found more traces of such impacts.
Unusual sounding noises
NASA has released the image of the first three impacts found. The noises reminiscent of a “blup”, which is due to a special effect of the Martian atmosphere, explains the US space agency. Because the speed of sound changes there in the middle of the spectrum that humans can hear, lower tones travel much faster on the red planet than higher ones. This was only discovered a few months ago based on measurement data from the Mars rover Perseverance. The Insight recording now makes it clear how unusual the background noise is there. A non-radio conversation in this environment would be extremely difficult even over a few meters.
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The impacts found so far occurred 85 to 290 kilometers from Insight. In total, the Mars lander team has waited three years for Insight to notice such meteorite impacts, explains Brown University specialist Ingrid Daubar. It is now unclear why the device has not detected more, she adds. Even if three more impacts were discovered later, that seems pretty little. After all, Mars orbits the sun directly inside the asteroid belt, so there are actually enough supplies. In addition, the atmosphere of Mars is much thinner than that of Earth, so falling chunks burn up much less frequently.
It is possible that other impacts were covered by disturbing noises. Based on the now known signature, however, the data should be searched again. If the number is confirmed, it could also have implications for our knowledge of the history of Mars. Impact craters reveal, among other things, how old a surface is. But you have to know how many impacts are to be expected in a period of time. Insights observations were now presented in the journal Nature Geoscience.
Probe soon without power
Insight has been on Mars since the end of November 2018. With a sensitive seismometer, the probe measures waves that are caused by earthquakes below the surface. From their echoes in particular, conclusions can be drawn about the structures on which they were reflected. Unlike on Earth, marsquakes are not triggered by plate tectonics processes, which do not exist on the red planet. Instead, the tremors in the crust of the “one-plate planet” are caused by stresses on the rock, triggered by the slow shrinking of the cooling planet.
With more and more dust covering the lander’s solar panels, it will soon run out of power. Until then, she should collect scientific measurement data for as long as possible, even if this means that she will run out of power sooner. When that will be the case is difficult to predict, the team confirms again. It currently looks like the lander will stop working between October and January.