A European space mission is due to take off this Monday to study the asteroid Dimorphos. This space rock was deviated from its trajectory in November 2022 during a planetary defense test conducted by NASA. Objective: to offer future generations insurance life in case an asteroid one day threatens to crash into our planet.
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Mission Dart: deflecting an asteroid, NASA’s crazy bet
Protecting humanity from the possibility of a future threat is the objective of the Hera space mission which is due to take off this Monday, October 7 (at 4:52 p.m. Paris time) aboard a Falcon 9 rocket from SpaceX from the Cape Canaveral launch base in the United States. Two years after the Dart mission, during which a NASA spacecraft managed to divert an asteroid (new window) 160 m in diameter by hitting it head-on, the European Space Agency (Esa) is responsible for go and examine this extraterrestrial rock which was 11 million kilometers from Earth at the time of the impact.
Costing 363 million euros and equipped with twelve instruments, the Hera probe carries two nanosatellites, Juventas and Milani, on board. The first will try to land on Dimorphos, a first on such a small object. It is equipped with a low-frequency radar and a gravimeter to probe the asteroid’s structure and measure its gravity field. The second will study the composition of Dimorphos using a multispectral camera and a dust detector. The goal? Collect data on site to better understand what happened when Dart crashed on the surface of Dimorphos (new window).
📽️ #HeraMission ‘s launch window opens tomorrow! But what is ESA’s 1st planetary defence spacecraft going to do? Watch our cartoon introduction – & then there’s a whole series to catch up on! pic.twitter.com/5QXGMtJSZS — ESA’s Hera mission (@ESA_Hera) October 7, 2024
All this information will be crucial in order to extrapolate its use to other scenarios. Because if the Dart experiment (“Double Asteroid Redirection Test”, in English) made it possible to demonstrate the feasibility of the technique, we need to know more to validate it and be able to determine what energy would be necessary, if necessary, to effectively deflect a threatening asteroid. By hitting it, NASA’s kinetic impactor, the size of a large refrigerator, managed to move it by reducing its orbit by 33 minutes. But it’s unclear what effects the impact had on the small asteroid.
The Chelyabinsk superbolide, a triggering event
No need to panic! To date, no asteroid directly threatens our planet, at least for the coming century (new window). Thanks to telescopes, space agencies have identified more than 90% of near-Earth objects (that is to say whose orbit brings them closest to the Earth) measuring more than 1 km in diameter, the threshold at from which a global catastrophe like the extinction of the dinosaurs (new window) could be envisaged. It is estimated that an object of this size crashes into Earth every 500,000 years. However, uncertainty remains regarding 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 around thirty kilometers above the Russian city of Chelyabinsk. The blast, equivalent to 35 times the Hiroshima bomb, shattered several thousand windows, injuring some 1,500 city residents who rushed to their windows to see what had caused it. this bright flash in the sky. It was following this event, which could have been dramatic, that NASA and its partners set up this planetary defense program.
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Enough to provide the future inhabitants of the Earth with life insurance. “The objective 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 that the day this risk materializes, they do not have to improvise. For the moment, there is no reason to worry about it. On the other hand, there are good reasons to take care of it“, explained French astronomer Patrick Michel, scientific manager of the European component of this unprecedented planetary defense test, in an interview given to LCI in November 2022.
Matthieu DELACHARLERY
