“Have no more energy, almost stop it”

• Ivo Landmann

  online editor

Spirit got stuck in the desert, Opportunity and Phoenix lost contact with Earth in a dust storm. Robots on Mars lead a rough life, and now the end is in sight for InSight, a lander that has been studying geological activity on the planet since 2018.

“I’m almost out of energy,” tweeted (the team of) the exhausted lander tonight. “I’ll stop soon.”

He remembers it last message from the Opportunity rover (“my battery is dead and it’s getting dark”) that made some cry in 2019. With the InSight lander meeting the same fate – too much Martian sand on the solar panels preventing it from recharging its batteries properly – the reactions on Twitter are once again emotional.

InSight is not a cart like Opportunity and its bigger successors Curiosity and Perseverance. InSight is a legged lander with one main task: to learn more about Mars’ interior.

The Martian robot had been given some amazing tools: a hammer, a seismometer to measure earthquakes, and a self-buried “mole” that was supposed to measure how hot or cold it is underground up to 5 meters deep. But despite two years of trying, the mole didn’t go deeper than 35 centimeters.

Other tools have been more successful. For the first time, Martian earthquakes have been measured with a sensitive seismometer placed directly on the Martian surface. It can also be seen on the last photo sent by InSight:

In total, InSight has measured more than 1,300 major and minor earthquakes. Fifty of them were so heavy that it could be determined where the epicenter was on Mars. The lander also provided new data on the different layers that make up the planet, the liquid core of Mars and the remnants of a previous magnetic field under the surface.

The strongest quake was measured in May this year, measuring 4.7, which was five times heavier than the strongest to date.

By measuring the shocks, planetary scientists also learn a lot about the composition of Mars.

“For the first time, we have observed seismic waves going through the crust and mantle a few times around the planet,” exclaimed John Clinton, a Mars researcher and seismologist at a Swiss research institute. “The quake was over 2,000 kilometers away, but the waves were so strong that the seismometer almost overloaded.”

“Thanks to InSight, we now have measurements of the interior of a planet other than Earth,” explains Inge Loes ten Kate, a planetary scientist at Utrecht University. ‘Mars is a layered planet like Earth with a core, mantle and crust. Thanks to InSight, we now know much better what the crust and upper mantle look like. And that this composition varies across the planet.’

The lander also found traces of ice below the surface. “With all this data, we can build better models of how the planet has changed over billions of years. And even though InSight is now out of service, the new data will allow us to move forward in time to see not just Mars, but planets.” in general. understand better.”

Last month, the lander took to Twitter to reflect on its years of activity on Mars. “I was lucky enough to live on two planets. Four years ago I arrived safely on the second, to the satisfaction of my family on the first. Thank you to my team for this journey of discovery, I hope you are proud.”

Even if it’s the end of the InSight story, other Martian robots still work. The Rover Curiosity (since 2012) is still circling Gale crater and its successor Perseverance, in Jezero crater, is just starting an important part of its mission: to leave tubes of Martian sand on the ground. A yet-to-be-launched European rover must collect those tubes in a few years and bring them back to Earth with the help of a space probe.

The Ingenuity helicopter is also still airborne. The device with a rapidly rotating double rotor made its 36th flight on December 10 and has now covered more than 7 kilometers. Soon the helicopter will try to fly over the hills.