Space. The last selfie of InSight Mars, the sad farewell to a historic mission

One last image for posterity. NASA’s InSight Mars mission is coming to an end. The module took its last selfie on April 24, after 1,211 days on the Red Planet. Covered in dust and sand, InSight won’t be able to go on much longer. NASA is at his bedside for his last, imminent days. Since its landing in 2018, the module has enabled many advances in the knowledge of Mars.

InSight takes the pulse and temperature of Mars

When the probe is launched on May 5, 2018, it is a great day for NASA, the National Center for Space Studies (CNES) and their German counterpart (DLR). As part of the Discovery program, InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or internal exploration of earthquakes, geodesy and heat fluxes) must study for the first time the structure of Mars. Until now, we only knew its surface. InSight must make it possible to discover what is hidden below.

For this, the module is equipped with a seismometer, an instrument for measuring the heat fluxes coming from the heart of the planet (called HP3) and a magnetometer. Simply put, InSight takes the pulse and temperature of Mars.

Arrived in November 2018 on Mars, its initial mission is scheduled to last two years. But as with all modules and probes sent by NASA, its development is made to be much more durable. After all, the Voyager 1 probe, launched in September 1977, continues to emit and has led to unexpected discoveries of our universe.

Earthquakes and the sound of the wind

Unlike other machines, InSight does not move, some tools are driven into the ground. HP3, however, has difficulty in sinking deep enough. After a few attempts, the scientists, not knowing what is blocking, prefer not to try to go further.

Quickly, the module allows major advances. InSight records the first earthquakes above Earth and… the sound of the wind on Mars. At the beginning of 2021, the mission is extended for two years. To “clean” the dust from the solar panels, the articulated arm is reprogrammed to pick up sand and drop it on the panels, the wind helping to remove some of the dirt.

The sound of the wind on Mars

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Historical and unexpected data

Today, its legacy is impressive: more than 1,300 earthquakes analyzed – the last of which, on May 4, 2022, had a magnitude of 5 on the Richter scale and made part of the planet vibrate for 6 hours – ; the most important meteorological data ever; and three geological layers studied (crust, mantle and core).

We now know that the crust is “thinner” than what scientists thought (25 to 40 kilometers) and that it is composed of three distinct layers. The core is molten and larger than expected (a radius of 1,800 km). Thanks to InSight, we know that “light” elements are mixed with the molten iron, lowering the melting point. This explains why the core is still molten although it has cooled considerably since its formation.

The magnetometer revealed remnants (or “ghosts”) of electric and magnetic currents. Surprisingly, magnetic signals appear to vary with time, indicating that they depend on solar winds interacting with the Martian atmosphere.

All of this data has made it possible to better understand the red planet and its capacity to perhaps one day harbor life.

Covered in dust, InSight put “to rest”

From now on, InSight displays the weight of these years of facing the winds and the sand: the cogs of its arm are seizing up, no longer allowing the “cleaning” of its solar panels which, covered with dust, can no longer produce enough energy. ‘energy. The only hope would be a very strong wind or a mini-tornado. “We were hoping for such a cleanup, as has been the case several times for the Spirit and Opportunity rovers,” explains Bruce Banerdt, head of the InSight mission at NASA. It’s still possible, but the energy level is so low that we are now focusing on recoverable scientific data. »

With heavy hearts, the researchers prepare the module for its final months. His arm will be placed “in the rest position” and most of the instruments will be on standby. Only the seismometer will be operational for a few hours a day until this summer. InSight will still be able to send some data or photos occasionally, but the batteries should be empty in December.

In February 2019, NASA sent as a “farewell message” to the unresponsive Mars rover Opportunity, the love song I’ll Be Seeing You, by Billie Holiday. Although nearly 60 million kilometers from Earth, InSight will not be extinguished in the world alone.

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