Large quake on Mars detected by Marslander InSight

The quake also lasted a very long time; about an hour and a half!

Last weekend, Marslander InSight celebrated its 1000th day on Mars. And that party was accompanied by a special detection; InSight recorded one of the largest Marsquakes ever. The quake had a magnitude of 4.2 and – with a duration of one and a half hours – also goes into the books as the longest quake that InSight has detected to date.

Almost missed

It would have been close if InSight had missed this major quake. Because originally it was the intention that all scientific instruments of the lander – including the seismometer – come to a standstill for a few months. A necessary evil, because Mars orbits the sun in an oval-shaped orbit and sped toward aphelion (the point in the orbit furthest from the sun). In the period around aphelion, less sunlight falls on InSight’s already quite dusty solar panels. To prevent the lander from experiencing an energy shortage and from being unable to keep crucial parts – such as the on-board computer and heating – running, it was planned to switch off all less necessary energy guzzlers for a few months sometime in June.

Solution

But then the InSight team came up with a very innovative way to wipe some dust from the solar panels and thus increase the energy yield. On a windy day, InSight’s robotic arm was allowed to scoop up some sand and then those grains of sand fell back down next to the solar panels. It was hoped that at least some of the sand – aided by the wind – would bounce off the solar panels and grab some dust particles, before being carried on by the wind again. The approach worked. And with the slightly cleaned solar panels, there was also enough energy available at a greater distance from the sun to keep the seismometer operational.

Three big tremors

And that has paid off. Because the major quake that the seismometer noticed this weekend is already the third major quake that InSight has registered in a month. At the end of August, two quakes with magnitudes 4.2 and 4.1 were recorded on one day.

Valuable

The Marsquakes are of great value to scientists. The quakes give off seismic waves that change as they travel through the crust, mantle and core of Mars. By studying the waves and the changes they undergo, researchers can gain more insight into the composition of Mars.

Analysis

The last major quake – which took place last weekend – has yet to be analysed. But the tremors of late August have already been investigated further. The research shows that the quake with a magnitude of 4.2 occurred no less than 8500 kilometers away from inSight. This makes it the furthest quake that InSight has detected to date. It is not yet clear where the quake originated. What is certain is that it could not have originated in the place where most of the quakes detected by InSight were born: Cerberus Fossae, an area that is about 1600 kilometers away from InSight. An intriguing possibility is that the quake recorded by InSight in late August originated in Valles Marineris — a massive rift system on Mars. The heart of this canyon system is some 9,700 kilometers from InSight.

Differ

What researchers have further noticed is that the two quakes detected in late August are very different from each other. For example, the magnitude 4.2 quake was characterized by slow, low-frequency tremors, while the other quake, which originated about 925 kilometers from InSight, had fast, high-frequency tremors. The differences are music to the scientists’ ears; recording tremors that originated at various distances from InSight and generate different types of seismic waves is very valuable for research into the structure of Mars.

Meanwhile, the distance between Mars and the sun is shrinking again and the energy that InSight can generate with the solar panels is increasing nicely. But a new challenge is already waiting: the Mars conjunction. Mars and Earth are on opposite sides of the sun. Because the radiation from the sun can affect radio signals, there is temporarily no communication between Earth and Mars. The last commands will be sent to InSight at the end of this month. Despite the radio silence, the seismometer continues to hunt for tremors.