from the listen-my-children-and-you-shall-hear dept.
NASA's InSight lander has detected seismic waves from four space rocks that crashed on Mars in 2020 and 2021. These represent the first impacts detected by the spacecraft's seismometer since InSight touched down on the Red Planet in 2018. In fact, it also marks the first time seismic and acoustic waves from an impact have been detected on Mars.
[...] A “meteoroid” is the term used for space rocks before they hit the ground. The first of the four confirmed meteoroids made the most dramatic entrance: It exploded into at least three shards that each left a crater behind after entering Mars’ atmosphere on September 5, 2021.
NASA's Mars Reconnaissance Orbiter then flew over the estimated impact site to confirm the location. The orbiter used its black-and-white Context Camera to reveal three darkened spots on the surface. After locating these spots, the orbiter's team used the High-Resolution Imaging Science Experiment camera, or HiRISE, to get a color close-up of the craters (the meteoroid could have left additional craters on the surface, but they would be too small to see in HiRISE's images). See the images in the "Mars Crater Collage" below.
“After three years of InSight waiting to detect an impact, those craters looked beautiful,” said Ingrid Daubar of Brown University. She is a co-author of the paper and a specialist in Mars impacts.
After combing through earlier data, researchers confirmed three other impacts had occurred on May 27, 2020; February 18, 2021; and August 31, 2021.
Scientists are perplexed as to why they haven’t detected more meteoroid impacts on Mars. The Red Planet is located next to the solar system’s main asteroid belt, which should provide an ample supply of space rocks to scar the planet’s surface. Additionally, far more meteoroids pass through Mars’ atmosphere without disintegrating because it is just 1% as thick as Earth’s.
InSight’s team suspects that noise from wind or seasonal changes in the atmosphere may have obscured other impacts. But now that the distinctive seismic signature of an impact on Mars has been discovered, researchers expect to discover more hiding within InSight’s nearly four years of data.
[...] However, the impacts will be critical to refining Mars’ timeline. “Impacts are the clocks of the solar system,” said the paper’s lead author, Raphael Garcia of Institut Supérieur de l’Aéronautique et de l’Espace in Toulouse, France. “We need to know the impact rate today to estimate the age of different surfaces.”
Scientists can calculate the approximate age of a planet’s surface by counting its impact craters: The more they see, the older the surface. By calibrating their statistical models based on how often they see impacts occurring now, researchers can then estimate how many more impacts happened earlier in the solar system’s history.
Two-minute TLDR summary with the actual sounds
Journal Reference:
Garcia, R.F., Daubar, I.J., Beucler, É. et al. Newly formed craters on Mars located using seismic and acoustic wave data from InSight. Nat. Geosci. (2022). DOI: 10.1038/s41561-022-01014-0
(Score: 2) by janrinok on Tuesday September 27 2022, @07:53AM