Mars mission InSight: look inside the red planet |

NASA’s InSight probe has been on Mars since November 2018, exploring our neighboring red planet. The Mars researchers are concentrating on the seismograph SEIS, which measures quakes on Mars. Researchers use this data to build an anatomical model of the interior of Mars. NASA scientists expect up to a hundred quakes during the roughly two-year InSight mission, which will end when the lander’s solar cells no longer produce enough electricity.

SEIS measures three large marsquakes

The coup then succeeded in the summer of 2021: SEIS was able to measure three large quakes within four weeks. The strongest made the Martian floor shake for about an hour and a half. The first two quakes in August were 4.2 and 4.1. And also the longest recorded earthquake in mid-September 2021 had a magnitude of 4.2.

From then on, the researchers’ focus was on what exactly can be found inside Mars. This was achieved in November 2021 with data from a depth of 200 meters. For the To analyse The scientists took into account not only the seismic tremors, but also surface vibrations, so-called seismic ground unrest, which is caused by wind. A model of the structure of the upper Martian crust could be developed from the recorded vibrations.

Structure of the surface layers of Mars

NASA's illustration shows the Mars lander InSight on the red planet.  InSight is scheduled to land on Mars and examine it.  |  Image: picture-alliance / dpa / NASA / JPL-Caltech

NASA’s illustration shows the Mars lander InSight on the red planet.

According to this, the surface of the Red Planet is covered by an approximately three-meter-thick layer of regolith, rock that has been crushed into granular material by erosion. Underneath, the researchers came across a 15-meter-thick layer of larger boulders, apparently ejected material from a larger meteorite impact. Further down there is a layer of lava about 150 meters thick. But within this lava layer, at a depth of 30 to 75 meters, the surface waves propagate much more slowly than expected for lava rock. The researchers interpret this zone as a sediment layer, fine-grain deposits caused by wind or water. According to this, the lava layer above and below was created at different times and thus through different volcanic eruptions.

Uncover three billion years of Martian history

At the same time, the scientists counted the craters on the Elysium Plain, on which the InSight lander is placed, and were able to date the age of the upper lava layer to 1.7 billion years, while that of the lower lava layer was 3.6 billion years. This layering resembles “a cake with different fillings”, according to the scientists, and gives a very specific seismic picture. This was the first time that the most important geological events of the last 3 billion years in the history of Mars could be traced for the first time.

Anatomy of Mars

It turned out that Mars is similar in structure to Earth. However, its crust is rather thin with a thickness between 15 to 47 kilometers. Below is the mantle with the lithosphere made of solid rock, which extends to a depth of 400 to 600 kilometers – twice as deep as on Earth. This could also have something to do with the only continental plate on Mars, in contrast to Earth with its seven large plates in motion.

“The thick lithosphere fits in well with the model of Mars as a ‘one-plate planet’.”

Amir Khan, scientist at the Institute for Geophysics at the ETH Zurich and at the Physics Institute at the University of Zurich.

The core radius of Mars is also larger than expected, namely around 1,840 kilometers. Since the core radius is so large, the researchers assume that its density is low and therefore – in addition to iron and nickel – must also contain a high proportion of lighter elements. This could be sulfur, but also oxygen, carbon or hydrogen. In any case, the studies confirm that the Martian core is, as suspected, liquid. This is unusual in that Mars no longer has a magnetic field today.

The Mars Mole HP3 – hammer drill at the end

In addition to the SEIS seismograph, the InSight probe is also equipped with the German HP3 drill. But the Mars mole, as the instrument is called by the responsible scientists at the German Aerospace Center (DLR), had major problems. The heat flow probe was supposed to be the first probe in the history of space travel to penetrate deep into the interior of Mars – up to five meters deep in order to gain deeper insights into the upper rock layers of Mars.

InSight delivers weather reports from Mars

If you want to know what the weather is like on Mars, you can look online: InSight now also provides us with weather data. On June 4, 2020, for example, the maximum temperature was -2 degrees Celsius and the minimum temperature -92 degrees Celsius.

But the soil conditions in this area are obviously completely different than expected. In the meantime, the mole got stuck at a depth of around 35 centimeters and in October 2019 the drilling robot took the completely wrong direction. In January 2021, those responsible therefore decided to finally abandon the project.

“We gave everything we could. But Mars and our brave mole just didn’t go together.”

Tilman Spohn, DLR Institute for Planetary Research

Sun sails on board

Besides the SEIS seismometer and the HP3 drill, InSight has other scientific instruments with it, including the RISE experiment (Rotation and Interior Structure Eexperiment). It measures small fluctuations in the axis of rotation of Mars and should thus also provide information about the internal structure of the planet.

InSight is testing its solar panel.  NASA's lander is supposed to land on the Red Planet and investigate it.  |  Image: picture-alliance / dpa / newscom

InSight weighs 360 kilograms. With the sun sails extended, the lander has a wingspan of around six meters.

InSight was built by Lockheed-Martin Space Systems in Denver. The design of the 360 ​​kilogram lander, with its sun sails extended, around six meters long and one and a half meters wide, is based on the Phoenix space probe, which landed on Mars in 2008 and transmitted data for a few months. InSights two sun sails each have a diameter of more than two meters.

“InSight is like a scientific time machine that tells us about the beginnings of Mars 4.5 billion years ago. It will help us understand how rocks form, such as the earth, its moon and even planets in other solar systems. “

Bruce Banerdt, InSight Scientist, Jet Propulsion Laboratory

InSight lands on Mars and takes its first photo

NASA lander InSight landed on Mars on November 26, 2018.  A few minutes after touching down, he has already sent the first images of the red planet to earth.  |  Image: NASA / JPL-CalTech

One of the first images InSight sent from Mars.

The NASA lander InSight landed on the evening of November 26, 2018 after a six-month, 500-million-kilometer journey on Mars in the Elysium Planitia plain, which is adjacent to several large shield volcanoes, north of the Mars equator. In a complicated maneuver, InSight had to be slowed down by brake rockets and a parachute after entering the Martian atmosphere – and at times withstand temperatures of around 1,500 degrees Celsius.

Animation shows InSight’s landing on Mars

InSight sends sounds and a selfie from Mars

First "Selfie" from Mars probe Insight |  Image: NASA / JPL-Caltech

InSight photographs itself on Mars

InSight also sent sounds from Mars to Earth: On December 9, 2018, NASA released sound recordings that InSight had made on Mars. You can hear the deep rumble of winds blowing on the Red Planet. The lander took his first selfie three days earlier: he photographed himself with the camera on his roughly two-and-a-half meter long robotic arm.

Wind noise on Mars

Sounds of Mars: NASA’s InSight Senses Martian Wind | Bild: NASA Jet Propulsion Laboratory (via YouTube)

Sounds of Mars: NASA’s InSight Senses Martian Wind

InSight takes off for Mars two years later than planned

InSight is scheduled to land on Mars and examine it.  This is what the NASA lander looks like.  Here it was strapped and rotated for testing.  |  Image: picture-alliance / dpa / newscom

For testing, the Mars lander InSight had to be placed in a kind of centrifugal drum on Earth.

InSight should actually have made its way to Mars in 2016. The start of the mission, which cost more than 600 million euros, was postponed due to an instrument that was not yet working properly. On May 5, 2018, the stationary lander was sent off to sniff with the aid of an Atlas V-401 rocket measuring around 57 meters. In addition to NASA scientists, researchers from nine other countries are involved in the mission, including the German Aerospace Center (DLR).

InSight takes a first look inside Mars

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