In a little less than a year, one NASA spacecraft will deliberately crash into the surface of an asteroid. The target; To make him deviate from his course. This mission, which is characterized “planetary defense” mission, is expected to allow humanity to be prepared for the threat of an asteroid impact in the future.
The script is reminiscent of that of the movie “Armageddon”, in which he Bruce Willis and Ben Affleck save the planet from a huge asteroid heading towards Earth. But the US space agency is conducting a very real experiment here. Although no known large asteroid is currently in collision, the point is to prepare for this eventuality.
“We do not want to be in the position where an asteroid will be directed towards the Earth and we will have to try this technique then” for the first time, explained yesterday, Thursday (4/11), in a press conference the Lindley Johnson of NASA’s Planetary Defense Division. The mission, dubbed DART (double arrow in the Asteroid Double Asteroid Redirection Test), will take off from California with a SpaceX Falcon 9 rocket at 22:20 (local time) on November 23rd.
Ten months later the spacecraft will hit its target, which will then be 11 million kilometers from Earth – that is, at a time when its distance from Earth is the shortest.
“A little hit”
In fact, the goal is twofold: first a large asteroid, Gemini, which is 780 meters in diameter, ie twice the height of the Eiffel Tower.
And in orbit around him, a moon, Dimorphos, 160 meters in diameter – taller than the Statue of Liberty.
It is on this moon that the ship, which is about 100 times smaller than it, will end its race with a speed 24,000 km / h, as reported by ΑΠΕ-ΜΠΕ. The collision will launch tons of materials into space.
But “it will not destroy the asteroid, it will just give it a small blow,” says Nancy Chabot of Johns Hopkins University Applied Physics Laboratory, which is leading this mission in partnership with NASA. Thus the orbit of the small asteroid around the large will only decrease by “about 1%”, explains.
Thanks to the observations made for decades with the telescopes on Earth, we know that Dimorphos is currently making a complete rotation around Gemini in exactly 11 hours and 55 minutes. With the help of these same telescopes, this period will be measured again after the collision. It will then probably be “11 hours and 45 minutes or something,” says the researcher.
How exactly? Scientists do not know and this is exactly what they want to discover. Numerous factors enter the equation, including the angle of impact, the surface appearance of the asteroid, its composition or even its exact mass, elements unknown until now.
In this way, “if one day an asteroid is discovered in the course of a collision with Earth, (…) we will have an idea of the power we will need so that this asteroid does not reach Earth,” explained Andy Cheng of Johns Hopkins University.
The orbit of Gemini, the large asteroid, around the Sun will also be slightly modified due to its gravitational relationship with its moon, Cheng said. But this change will be “too small to measure. It is therefore a very safe experiment, “he explained.
A small satellite will also make this trip. He will be released from the main boat ten days before the collision and will use his own propulsion system to deviate slightly from its course. Three minutes after the collision, it will fly over Dimorphos to observe its effect and possibly the crater on the surface. The total cost of the shipment is $ 330 million.
If this test is successful, “we believe that this technique could be part of a toolbox that we are beginning to fill so that we can make an asteroid deviate from its course,” explained Lindley Johnson. He cited, for example, methods by which the gravitational force of a flying ship near an asteroid could be used over a long period of time or even the use of lasers.
But he reminded that the key is to identify potential threats first. “The strategy is to find these objects not only years, but decades before any risk of collision with Earth”, he underlined. About 27,000 asteroids near the blue planet are currently known.
THE asteroid Bennu, with diameter 500 meters, is one of two asteroids that have been detected in our solar system and pose the greatest threat to Earth, according to NASA. But from now until year 2300, the risk of collision is just 0.057%.