The end is near for InSight, the Martian lander

On May 5, 2018, a rocket Atlas V 401, the rocket the most reliable there is, takes InSight – the result of a collaboration between Germany, France and the United States – to the distant world of Mars. InSight is a lander that takes the first seismometer designed to pierce information about the interior of the Red Planet, because if the first martian seismometers date probes vikingthey were in practice unusable for detecting and analyzing possible earthquakes martians. On November 26 of the same year, the 358-kilogram lander discovered the desolate landscape of Elysium Planitia, a region near theequator Martian, which will be his final resting place.

The end is coming

Unfortunately, all good things come to an end, and InSight is no exception. The small probe is now completely covered with Martian dust and more and more, which will prevent the solar panels from providing energy and which, within a few months, will cause the death of the probe.

Let’s keep our tears, the probe has more than fulfilled its mission! All space probes are designed for duration nominal mission, and can, if successful, benefit from a mission extension. This was the case for InSight which completed its objectives in 2020 and which has been able to continue to collect valuable data until today. But, as for old probes equipped with solar panels, life is not eternal on the red planet.

The teams in charge of the mission have nevertheless succeeded in extending the life of the probe in an unprecedented way. To remove some of the dust, one technique that worked was to… add more dust! Thanks to the small shovel that equips the platform, the engineers were able to throw a pile of dust on the panels, and the fall made it possible to a certain extent to sweep, in a way, the surface and to grab a little more light. In other cases, the storms and the winds of Mars also make it possible to sweep the panels and to lengthen thelife expectancy from robotsas it may have benefited the Opportunity rover for example.

If such an event were to occur and InSight could be cleaned as Opportunitythe probe has plans for a new mission extension, but such an eventuality is considered unlikely according to officials.

Why not clean the solar panels?

Dust can be cleaned well, however, so why didn’t the teams in charge think of including a small broom or a small blower? Of course, they thought about it, it’s their job, but there are several reasons that make any such attempt impossible. The first is very simple: mass. Add a system to propelair or to sweep is to add more weight and further constrain the success of the mission. On the other hand, this also represents an additional cost, even for small instruments, not to mention the specifications which become heavier on a project which is already calculated and dimensioned in an optimal way, from the point of view of the mass, but also electrical energy.

The other reason is that a compressed air system does not remove fine dust, we can experience it at home: blowing is effective against large dust bunnies, but for fine dust that has stuck over the years to the old furniture, you have to scrub. For Martian dust, it is even worse, it is very fine and thanks to the effects electrostaticit adheres enormously to surfaces, it sticks.

A small brush then? No more ! In addition to being very sticky, Martian dust is very abrasive. Trying to sweep it would reduce the life of our dear probe even more quickly.

In summary, a lot of additional stress for not much, because the dust on the solar panels is not the only predator of our martian robots. phoenix, twin from InSight, landed very far north of the planet, this is the dry ice and the cold that got the better of him. For Spirithe got stuck in the sandimmobilized in a position which deprived its solar panels of light, dust or not, it ended up going out.

Its twin Opportunity has enjoyed remarkable longevity, martian winds allowed him to clean himself regularly, but after 14 years he was caught in a vast global dust storm, which covered not only his panels, but the whole sky. the Sun then disappeared gave way to a long darkness, ending the odyssey of the roverno brush could have saved him.

Only Zhurong, the Chinese rover, will experiment with cleaning its solar panels. They are covered with a special coating that should prevent dust from sticking to them. Then the panels should rise vertically to just let the dust fall out.

And Curiosity or Perseverance then?

The two behemoths of Mars exploration, which arrived on Mars in 2012 and 2021 respectively, do not experience this kind of problem, because they simply do not have solar panels.

The reason is that solar panels are very inefficient, because the planet Mars is quite far from the Sun. Solar power may be appropriate for small probes with fewer instruments on board, not for large rovers.

No, Perseverance and Curiosity are themselves equipped with generators radioisotope thermoelectrics (RTGs), which use the heat generated by the radioactivity (from plutonium in general) to generate electricity (not to be confused with the principle of our nuclear center who use the nuclear fission to generate heat, not radioactivity). This principle has the advantage of being able to power a large number of scientific instruments, and therefore to power a larger rover, and for years to come, without depending on sunlight. On the other hand, it is an extremely expensive technology which would not be suitable for small probes like InSight financed by smaller budgets.

Ultimately, we need to let InSight enjoy its final months and remember it as the probe that first revealed the mysterious interior of the planet of the god of war.