- Jonathan Amos
- BBC science journalist
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1 hour ago
photo released, NASA / JHU-APL
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The probe will only be able to discern its target in the last 50 minutes or so (the image is the work of an artist).
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In the next few hours, a NASA probe will collide with an asteroid.
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The purpose of the probe, “DART”, is to find out how difficult it is to prevent a large rock in space from colliding with Earth.
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This test is taking place about 11 million kilometers away on a target called Dimorphos.
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The agency says “the rock is not currently on its way to hit Earth and the test will not accidentally change direction to head for Earth.”
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The collision will occur on Monday at 23:14 GMT. Telescopes will monitor it from afar, including the new James Webb Hyperspace Observatory.
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We have all seen how Hollywood portrayed him with brave astronauts and nuclear weapons.
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But how do we protect Earth from a true killer asteroid?
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NASA is getting closer to discovery. The idea is simply that a spaceship collides with an asteroid.
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The idea is to have to change the speed of the rock by a small amount to change its course, so that the Earth misses, provided that this happens with sufficient distance and time in advance.
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Dart’s double asteroid redirect test mission will test this theory by colliding almost directly with the 160-meter-wide Demorphos at a speed of more than 20,000 kilometers per hour.
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This is expected to change its orbit around a much larger asteroid, called Didymus, by a few minutes a day.
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NASA promises to get some stunning images from the 570-kilogram Dart spacecraft when it began the impact process.
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photo released, ERA / ESA
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The European Space Agency will continue the mission (Image is the work of an illustrator)
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“The DART mission is the first planetary defense test mission to demonstrate the effectiveness of a spacecraft collision with an asteroid to slightly shift its position in space,” said Dr Nancy Chabot, who works in Johns Hopkins University’s applied physics laboratory, and is leading the NASA mission.
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He added in a BBC interview: “This is what you would do years ago, if you needed it, to give the asteroid a little push to change its position in the future so that Earth and the asteroid are not in. collision course. ”
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And beating Demophos will be the big challenge. The Dart spacecraft will be able to distinguish its Demorphos target from Didymus, which is 780 meters wide, only in the last 50 minutes or so.
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The probe’s navigation software must then adjust the spacecraft’s trajectory to create a direct hit.
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“Due to the speed of light and the distances involved, it is not really possible to have a pilot sitting on the ground with a joystick in the spacecraft. There is not enough time to respond,” said Dr. Tom Statler, a NASA Dart. program scientist.
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“We had to develop software that could interpret the images taken from the spacecraft, understand the correct target and perform trajectory correction maneuvers by firing the thrusters.”
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It will bring the images back to Earth at the rate of one image per second as it heads for the “deep fist”. What initially appears as a point of light in the images will rapidly grow to fill the entire field of view, before the power is cut abruptly when the spacecraft is destroyed.
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Fortunately, this is not the end of the story. He was carrying an Italian cube satellite weighing 14 kg, launched a few days ago. His job is to record what happens when DART digs a hole in an asteroid.
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His images, taken from a safe distance of 50 km, will reach Earth in the next few days.
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“The moon will pass through Lyciacube about three minutes after the DART collision,” said Simone Perotta of the Italian Space Agency.
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He added: “This timing was chosen to allow things to fully develop because one of the main contributions of” LichiaCube “is to document what happened and confirm the deflection of the asteroid’s orbit.”
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photo released, ERA / ESA
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Currently, Demorphos takes about 11 hours and 55 minutes around Didymus. The collision is expected to change the momentum of the smaller object, reducing the orbital period to about 11 hours and 45 minutes. The telescope measurements will confirm this in the coming weeks and months.
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And space investigations, coupled with statistical analyzes, indicate that we have identified more than 95 percent of ferocious asteroids that could begin to become extinct globally if they collide with Earth (and wouldn’t if they calculated their trajectories and knew they didn’t. they wouldn’t get close to our planet). But that still leaves many little things undiscovered that can wreak havoc, even if only at the level of a region or city.
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And if an object like Demorphos hits the ground (which it doesn’t), it could dig a hole one kilometer in diameter and a few hundred meters deep. The damage will be severe in the vicinity of the impact.
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In four years, ESA will have three spacecraft – collectively known as the HERA mission – to engage with Didymos and Demorphos and conduct further follow-up studies.
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