In a few weeks, NASA controllers will deliberately crash their $330 million Dart spacecraft into an asteroid. The half-ton probe will be traveling at more than four miles per second when it hits its target, Dimorphos, and will be destroyed.
The goal of this kamikaze science mission is simple: space engineers want to learn how to deflect asteroids in case one is discovered on a collision course with Earth. Observations of Dart’s impact in Dimorphos’ orbit will provide crucial data on how spacecraft can protect Earth from asteroid armageddon, they say.
“We know that asteroids have hit us in the past,” said Professor Alan Fitzsimmons, an astronomer at Queen’s University in Belfast. “These impacts are a natural process and will occur in the future. We would like to stop the worst of them.
“The problem is that we’ve never tested the technology that will be needed to do that. That’s the purpose of Dart,” said Fitzsimmons, a member of the science team on the Double Asteroid Redirect Test (Dart) mission. . Launched last November, the probe is scheduled to reach its target in the early hours of September 27, BST. By carefully studying the trajectory of the asteroid after the collision, scientists believe they will better understand how similar collisions could be used to deflect asteroids and comets away from Earth.
“Dart’s target has been carefully chosen,” said Jay Tate, director of the National Near-Earth Object Information Center in Knighton, Powys. “Dimorphos actually orbits another larger asteroid called Didymos, and the extent of the deflection caused by the accident will be easier to detect as astronomers have been carefully watching its path around the larger asteroid “.
Asteroid and comet impacts have had major effects on life on Earth in the past. The best-known collision occurred 66 million years ago, when a 10 km wide asteroid hit Chicxulub on Mexico’s Yucatan Peninsula. The collision created an explosion that had the energy of several billion atomic bombs and resulted in the destruction of 75% of all plant and animal species, including all terrestrial dinosaurs.
Since then, movies like Don’t look up, Armageddon i Deep impact have represented similar devastation caused by asteroid or comet impacts in modern times. However, astronomers believe that we are unlikely to experience such catastrophic impacts in real life in the near future.
“We know where the big asteroids are because we can see them with our current generation of telescopes, and we know that none of the detected asteroids will come close to our planet for the next two hundred years or so. So we can rest assured that our beds on these,” Fitzsimmons added.
“However, many smaller ones have yet to be detected, and they are still large enough to destroy entire cities and devastate large areas. We are mapping these smaller objects with increasing precision, but we will need to be ready to act if we find one headed for Earth. Dart is the first step in making sure we have the right technology to deal with the threat.”
It’s a point supported by NASA planetary defense officer Lindley Johnson, who stressed the importance of developing asteroid deflection technology as soon as possible. “We don’t want to be in a situation where an asteroid is headed for Earth and then has to test that kind of capability.”
An example of the danger posed by small asteroids and comets is provided by the rocky object that entered Earth’s atmosphere near the Russian city of Chelyabinsk on February 15, 2013. Thought to be 20 meters in diameter, it exploded into the atmosphere, causing a 400 kiloton explosion that injured more than 1,500 people.
“If this object had entered the atmosphere about 20 km further north than it did, it would have done much more damage to the city,” Tate said. “We’ve been very fortunate not to have suffered substantial casualties from these things within living memory. We have to be aware that they’re going to happen someday and be prepared to do something about it.”
Dart’s target, Dimorphos, is 160 meters in diameter and orbits its parent asteroid every 12 hours. Ten days before impact, the spacecraft will launch a bag-sized Italian probe, called LiciaCub, which is equipped with two cameras that have received the War of the galaxies-names inspired by Luke and Leia. Footage of Dart’s asteroid impact will be recorded by Luke and Leia and relayed to ground controllers.
Ground-based telescopes will then study the asteroid and determine how its orbit has changed. “That way, we’ll get an idea of how easy it will be to deflect incoming asteroids or comets,” Tate said.
In addition, the European Space Agency is set to send a robot ship, Hera, to Dimorphos in 2024 to study the crater left by Dart and analyze its collision with the asteroid.
“Bumping Dimorphos is not going to be easy,” Fitzsimmons said. “It’s only 160 meters in diameter and the spacecraft will travel at four miles per second. Hitting the asteroid dead center, where the crash will have the most effect, will push Dart’s autonomous navigation devices to their limits.
“The engineers and scientists at NASA have done an extraordinary job, and they are confident that this should absolutely work. But you never know until you do,” Fitzsimmons said.
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