The goal of this kamikaze science mission is clear: 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 critical data on how well the spacecraft can protect Earth from asteroid Armageddon, they say. “We know that asteroids have hit us in the past,” said Professor Alan Fitzsimons, an astronomer at Queen’s University Belfast. “These effects are a natural process and are going to happen in the future. We would like to stop the worst of them. “The problem is that we’ve never tested the technology that would be needed to do this. That’s the purpose of Dart,” said Fitzsimmons, a member of the science team for the Double Asteroid Redirection Test (Dart) mission. Launched last November, the probe is scheduled to hit its target in the early hours of September 27, BST. By carefully studying the path of the asteroid after the collision, scientists believe they will better understand how similar collisions could be used to deflect Earth-bound asteroids and comets. “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 Gemini, and the extent of the deflection caused by the crash will be easier to detect as astronomers carefully observe its path around the larger asteroid.” Impacts from asteroids and comets have had major impacts on life on Earth in the past. The most famous collision occurred 66 million years ago, when a 10 km wide asteroid hit Chicxulub on the Yucatán Peninsula in Mexico. 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 land dinosaurs. Since then, films such as Don’t Look Up, Armageddon and Deep Impact have depicted similar disasters caused by asteroid or comet crashes in the modern era. However, astronomers believe that we are unlikely to experience such catastrophic effects in real life in the near future. Leonardo DiCaprio and Jennifer Lawrence in Don’t Look Up, a movie about two astronomers who try to warn of a comet headed for Earth. Photo: Niko Tavernise/AP “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 anywhere near our planet for the next hundred years or so. So we can rest easy in our beds about them,” Fitzsimmons added. “However, many smaller ones have yet to be detected and are still large enough to destroy entire cities and destroy large areas. We are mapping these smaller objects with increasing precision, but we should be prepared to act if we find one that is on its way to Earth. Dart is the first step in ensuring we have the right technology to meet the threat.” It’s a point supported by Nasa’s planetary defense officer, Lindley Johnson, who has 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 toward Earth and then we have to test this 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 in the atmosphere, causing a 400 kiloton blast that injured more than 1,500 people. “If this object had entered the atmosphere just 20 kilometers further north than it did, it would have done much more damage to the city,” Tate said. “We’ve been very fortunate that we haven’t had any significant losses from these things in living memory. We have to know that they will happen one day and be ready to do something about them.” Archie Bland and Nimo Omer take you to the top stories and what they mean, free every weekday morning Privacy Notice: Newsletters may contain information about charities, online advertising and content sponsored by external parties. For more information, see our Privacy Policy. We use Google reCaptcha to protect our website and Google’s Privacy Policy and Terms of Service apply. Dart’s target, Dimorphos, is 160 meters in diameter and orbits its parent asteroid every 12 hours. Ten days before impact, the spacecraft will release an Italian-made, wallet-sized probe called the LiciaCub, which is equipped with two cameras named Luke and Leia, inspired by Star Wars. Images of Dart’s asteroid impact will be captured by Luke and Leia and transmitted to ground controllers. Earth-based telescopes will then study the asteroid and detect 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. A tidal wave hits New York in director Mimi Leder’s 1998 film Deep Impact, which also features a deadly comet. Photo: Dreamworks/Allstar Additionally, the European Space Agency is set to send a robotic spacecraft, Hera, to Dimorphos in 2024 to study the crater left by Dart and analyze its collision with the asteroid. “Beating Dimorphos won’t be easy,” Fitzsimmons said. “It’s only 160 meters in diameter and the spacecraft will be traveling at four miles per second. Hitting the asteroid dead center – where the crash will have the most impact – will push the Dart’s autonomous navigation devices to their limits. “NASA’s engineers and scientists have done a tremendous job and are confident that this will definitely work. But you never really know until you do,” Fitzsimmons said.
