‘Don’t get any more energy, almost quit’

• Ivor Landman

  online editor

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

“I lack energy” tweeted (the team of) the lander exhausted tonight. “I will be quitting soon.”

It reminds him Last message of the Opportunity (“my battery is low and it’s dark”) rover that brought some to tears in 2019. While the InSight lander meets the same fate – too much Martian sand on the solar panels preventing it from properly recharging its batteries – the reactions on Twitter are again emotional.

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

The Martian robot had been given a few hard-hitting tools: a hammer, a seismometer to measure earthquakes and a self-buried “mole” that was to measure how hot or cold it was underground up to 5 meters deep. But despite two years of testing, the mole did not go deeper than about 35 centimeters deep.

Other instruments have had more success. For the first time, Martian earthquakes have been measured with a sensitive seismometer placed directly on the Martian surface. It can also be seen in 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 was possible to determine where the epicenter was on Mars. The lander also provided new data on the different layers that make up the planet, Mars’ liquid core and remnants of an ancient magnetic field below the surface.

The strongest earthquake was measured in May this year, measuring 4.7, 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 traversing the crust and mantle a few times around the planet,” exclaimed John Clinton, Mars researcher and seismologist at a Swiss research institute. “The earthquake 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, planetary scientist at the University of Utrecht. “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 top layer of the mantle look like. And that this composition varies across the planet. “

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

Last month, the lander took to Twitter to reflect on his active years on Mars. “I was lucky enough to live on two planets. Four years ago, I arrived safe and sound on the second, to the satisfaction of my family on the first. Thanks to my team for this journey of discovery, I hope you’re proud of it.”

Even though this is the end of the story for InSight, other Martian robots continue. Rover Curiosity (since 2012) is still circling Gale Crater, and its successor Perseverance, in Jezero Crater, is just beginning an important part of its mission: leaving tubes of Martian sand on the ground. A European rover which has not yet been launched must recover these tubes in a few years and bring them back to Earth using a space probe.

The Ingenuity helicopter is also still flying. The fast-spinning twin-rotor craft made its 36th flight on Dec. 10 and has now traveled more than 7 kilometres. Soon the helicopter will try to fly over the hills.