Life insurance for Earth’s future: The Hera probe attacks the asteroid Dimorphos

The Hera space mission took off on Monday from the Cape Canaveral launch base in the United States.

The European craft is headed for Dimorphos, an asteroid that was diverted from its orbit by NASA during a planetary defense test.

Goal: to offer future generations life insurance if an asteroid one day threatens to crash into our planet.

Protecting humanity from the possibility of a future threat is the purpose of the Hera space mission, which took off on Monday, October 7 from the Cape Canaveral launch base in the United States. Two years after the American Dart mission, in which a NASA spacecraft managed to redirect an asteroid (new window) 165m diameter by hitting it with the head, the European Space Agency (ESA) is responsible for going there to investigate this extraterrestrial rock. The ship

Hera will reach its target in October 2026 before it begins its investigations in December and for a period of six months.

The Hera probe costs 363 million euros and is equipped with twelve instruments and carries two nanosatellites, Juventas and Milani, on board. The first will attempt to land on Dimorphos, the first on an object of such a small size. It is equipped with a low-frequency radar and a gravimeter to probe the asteroid’s structure and measure its gravitational field. The second will study the composition of the asteroid using a multispectral camera and a dust detector. The goal? Collect information in situ to understand what happened when Dart crashed on the surface of Dimorphos (new window).

Thanks to this data, researchers will be able to extrapolate the use of this technique known as kinetic impact to other scenarios. Because if the Dart experiment has demonstrated its feasibility, its effects still need to be validated, especially to know the amount of energy to be used, if necessary, a threatening asteroid. What we know now is that the NASA spacecraft managed to move it by reducing its orbit by 33 minutes. But it is unclear what impact the impact had on the small asteroid.

Chelyabinsk superbolide, a triggering event

But don’t panic, no asteroid directly threatens our planet, at least in the coming century (new window). Thanks to telescopes, space agencies have identified more than 90% of near-Earth objects (that is, whose orbits bring them closest to Earth) that measure more than 1 km in diameter, the threshold from which a global catastrophe like the extinction of the dinosaurs (new window) could be considered. It is estimated that an object of this size crashes into Earth every 500,000 years. However, there is still uncertainty about those with a diameter of more than 140 m, the threshold for a regional disaster.

On February 15, 2013, a meteor that had not been detected by space agencies disintegrated at an altitude of about thirty kilometers above the Russian city of Chelyabinsk. The blast, equivalent to 35 times the Hiroshima bomb, shattered several thousand windows and injured about 1,500 residents of the city, who rushed to their windows to see what had caused this bright flash in the sky. It was after this event, which could have been dramatic, that NASA and its partners created this planetary defense program.

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Enough to provide life insurance for Earth’s future inhabitants. “The goal of the Dart and Hera missions is to provide future generations, who we know will one day need it, with a validated, robust and coordinated plan. So the day this risk materializes, they don’t have to improvise. For now, there is no need to worry about it. On the other hand, there are good reasons to take care of it“, French astronomer Patrick Michel, scientific leader of the European component of this unprecedented planetary defense test, explained in an interview given to LCI in November 2022.