How often is Mars hit?

As mentioned in the Lite bulletin released two weeks ago, I will endeavour to make a link between this and the previous Astronomy in the News bulletin. This week I will be discussing a result from a study on the planet Mars. In the AITN news bulletin last week (#44), I discussed the potential for life on the planet. Here I will be discussing the following article:

(If you follow the link through, there is a free version of the research paper although I don’t know how long that will last!)

This article discusses some results from the InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) mission. I discussed this mission in Astronomy in the News #14. The goal of InSight is to use the onboard seismometer to measure marsquakes (seismic events) on the planet to determine the 3D structure of the interior. By doing so, astronomers can determine the early geological activity on Mars, and constrain formation models of the terrestrial planets within the Solar System.

One of the other results from the mission is to determine how many times Mars is hit by meteoroids. The impact from the space rock would cause the seismometer to measure a marsquake. However, such is the sensitivity of the instruments on board, it was able to detect 3 events. The first was when the meteoroid entered the atmosphere, producing a shock wave that “tipped” the instrument. The second occurred when it exploded into multiple objects, and the third was the impact on the surface. The measurements from InSight pinpointed a rough location for the impact crater, and this was confirmed by comparing before and after images of the surface.

This is valuable data for the InSight mission since all seismic events are not marsquakes, and by highlighting which are and are not seismic events helps their models. Another potential consequence of these data are that they can work towards determining the impact rate on the surface of Mars. The number of impact craters on a surface, such as the Moon, are used as a geological clock.

Curriculum topics to be considered
Propagation of sound waves

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