Science & Space
When reality meets science fiction…
Surely the dinosaurs would have liked to think of that. Science fiction movies, likeArmageddon or more recently Don’t Look Up: Cosmic Denialhave been considering it for a long time.
This time, NASA will finally attempt what has never been done before: deviate the trajectory of an asteroid by projecting a kamikaze ship on it. A “planetary defense” test, which should make it possible to better protect humanity against a possible future threat. The Dart mission (dart, in English) took off in November from California. After ten months of travel, the spacecraft should hit the asteroid Dimorphos at 23:14 GMT Monday (01:14 Tuesday in Belgium), at a speed of more than 20,000 km / h. The ship is no bigger than a car, and its target is about 160 meters in diameter (half the height of the Eiffel Tower).
A test phase
Do not panic, Dimorphos does not represent a threat to the Earth in any way: its orbit around the Sun passes only seven million kilometers from us at its closest. But the mission “is important to realize before we discover a real need”, said Andrea Riley, in charge of the mission at NASA. The moment of impact promises to be spectacular and can be followed live on the American agency’s video channel. It is not a question of destroying the asteroid but of pushing it slightly. The technique is called kinetic impact.
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Dimorphos is actually the satellite of a larger asteroid, Didymos (780 meters in diameter), which it circles in 11 hours and 55 minutes. The goal is to reduce Dimorphos’ orbit around Didymos by about ten minutes. This change can be measured by telescopes from Earth, by observing the variation in brightness when the small asteroid passes in front of the large one.
The objective may seem modest but this demonstration is crucial for the future. The aim is to better understand how Dimorphos, representative of a population of fairly common asteroids, whose exact composition is not known, will react. The effect of the impact will largely depend on its porosity, i.e. whether it is more or less compact.
The event will also be observed by the Hubble and James Webb space telescopes, which should be able to detect a bright cloud of dust. Then, the European Hera probe, which is due to take off in 2024, will closely observe Dimorphos in 2026 to assess the consequences of the impact and calculate, for the first time, the mass of the asteroid.
With Belgium