SPACE – It is a setting worthy of the movies Armageddon Y don’t look up. What would happen if an asteroid hit the Earth directly? A hypothesis seriously studied by NASA and the European Space Agency (ESA), which dedicate the DART and HERA missions to it, as you can see in the video above.
What is the DART mission?
This mission began on November 24, when the space agency sent a spacecraft aboard a Falcon 9 rocket. This module should crash on the night of September 26-27 at 1:14 am French), at a speed of 24,000 km/h over the asteroid Dimorphos, a small ” Moon “ that revolves around a larger asteroid, Didymos, located 11 million kilometers from Earth.
“The Dimorphos target is the perfect size for this type of mission, because it’s really the size of an object that could be a problem for us one day.details in HuffPost Naomi Murdoch, one of the scientists on the DART mission. Why ? Because there are many asteroids of this size that we don’t know about yet and that’s where a threat could one day come from. » Rest assured, Dimorphos poses no threat to Earth: its orbit around the Sun passes, at its closest, just 7 million kilometers from us.
The moment of impact between the spacecraft sent by NASA and the asteroid promises to be spectacular, and can be followed live through the video channel of the American agency. This life-size experiment aims to modify the period of revolution of the small asteroid around the larger one. “Right now, Dimorphos takes 11:55 to go around Didymos. The impact of DART is believed to shorten the period by 10 minutes.”says Naomi Murdoch. Returning to the terrestrial scenario, the objective is to find out if humanity is capable of voluntarily modifying the trajectory of an asteroid that would threaten our planet.
A kamikaze space mission
To hit such a small target, the spacecraft will steer autonomously for the last four hours, like a self-guided missile. Its camera, called Draco, will take at the last moment the first images of the asteroid, whose shape we still do not know. At a rate of one frame per second, viewable live on Earth with a (small) 45-second delay.
Three minutes after impact, a shoebox-sized satellite, called LICIACube and launched by the spacecraft a few days ago, will pass within 55 km of the asteroid to capture images. They will be sent back to Earth in the coming weeks and months. But to have real data on the impact of DART, we will have to wait for the European probe HERA.
This probe must take off in October 2024 to reach Dimorphos in 2026. Objective: return to “crime scene” assess the consequences of DART’s impact. “She will give us the detailed result in terms of the size of the crater. But she will also give us, for the first time, detailed information about the internal structure of an asteroid. It was never done. And this thanks to a radar whose expertise is French”explains Patrick Michel, director of research at CNRS and scientific director of the Hera mission at ESA.
Scientists hope to be surprised by the results of the investigations. Because “we ignore almost everything” of these celestial bodies, indicates the astrophysicist. “It is a new world that we are going to discover”. For him, the asteroids They are not just pebbles boring through space, but fascinating and complex little geological worlds, with craters, basins, rock fields, particle ejecta… »
But it is difficult for science to understand these territories because on their surface gravity is very weak compared to that of Earth: the behavior of matter there is “Totally counter-intuitive, we can’t rely on images to know how asteroids behave, we must also ‘touch’ them”Patrick Michel insists.
Back to the origins of the solar system
Binary systems, such as Didymos and its satellite Dimorphos, make up about 15% of known asteroids and have so far gone unexplored. Shape, mass, chemical composition, internal structure, impact resistance, shape of the crater caused by DART: HERA’s instruments should reveal the secrets of Dimorphos. At the end of the mission, a microsatellite will even land on its surface to measure how it bounces back.
“Today we are in an era when all solid surfaces in the Solar System have craters. To get back to the original scenario, we need to understand what happens when two bodies collide.”. Not in the laboratory, but on a real scale thanks to the DART-HERA couple, scientists hope.
See also in The HuffPost :
#DART #mission #NASA #hit #asteroid #save #planet