The incident in Russia was a warning.
One winter morning in 2013, a meteor the size of a four-story building screamed across the country, exploding near the city of Chelyabinsk and injuring more than 1,600 people amid extensive property damage.
The piece of rock and iron, which measured 60 feet in diameter, was a stark reminder that the Earth, bombarded daily with tons of space debris, periodically crosses paths with large planet killers – and a significant portion of these remain undocumented.
After years of study and discussion, NASA launched its first effort to spare Earth the kind of calamity that extinguished dinosaurs, by crashing a space probe into an asteroid to alter its speed and trajectory. The Dual Asteroid Redirection Test (DART) took off on November 23 local time aboard a SpaceX rocket from California and will sail for 10 months to a binary asteroid system.
The idea is that if humans have enough time to react – decades of notice being better – enough energy can be transferred into a fast rock to alter its trajectory and cause it to miss Earth, thus avoiding disaster until at and including an extinction event. (Although this is a popular topic in science fiction, it should be noted that NASA’s current asteroid detection techniques toolkit does not include Morgan Freeman, Bruce Willis, or nuclear weapons.)
Given the critical nature of the work, it is “no exaggeration to suggest that DART may be one of the most important missions ever undertaken by NASA,” wrote Casey Dreier, analyst at the Planetary Society, in a commentary. November note to members.
“This test should demonstrate that this technology is mature enough to be ready if a real asteroid impact threat is detected,” said Lindley Johnson, NASA planetary defense officer, at a conference. press November 4.
In September of next year, if all goes according to plan, the DART craft will target Dimorphos, the smallest 530-foot rocky body gravitationally linked to the larger Didymos, which measures nearly 2,600 feet in diameter. The two rocks move about 1 kilometer (0.6 mile) apart, and Dimorphos orbits its big brother every 11 hours and 55 minutes, “like clockwork,” Johnson said.
Traveling at around 15,000 mph, the craft, which weighs 1,344 pounds and measures 59 feet in diameter, must collide head-on with Dimorphos to slow the rock down for a fraction of a second and adjust its orbital period around the larger asteroid. several minutes.
“It’s about measuring momentum transfer: how much momentum do we put into the asteroid when hitting it with the spacecraft? Said Andy Cheng, principal investigator of the mission at the Applied Physics Laboratory at Johns Hopkins University, which built and operates the spacecraft.
Didymos was discovered 25 years ago and has been well analyzed (as asteroids and comets disappear). Its course is not expected to meet Earth in the future, but its relatively close trajectory provides scientists with a good test platform to observe with telescopes around 6.8 million kilometers away.
DART will use laser targeting and other high-resolution technologies to autonomously choose its point of impact. As it rushes towards the rock, the craft’s camera will send images to Earth. A small satellite cube released from the main ship prior to impact will also record images from a safe distance. A big unknown: the composition of the surface and the topography of the smaller body, which are too small to be determined from Earth.
For more than 15 years, NASA has been ordered by Congress to catalog near-Earth objects (NEOs) over 140 meters (460 feet), the size at which an asteroid strike would cause enormous devastation. “Although no known asteroid larger than 140 meters in size has a significant chance of hitting Earth in the next 100 years, less than half of the estimated 25,000 near-Earth objects 140 meters and larger have been found. to date, ”according to the NASA Planetary Defense Coordination Office.
The 2013 Chelyabinsk incident caught Washington’s attention, with funding for planetary defense increasing by more than 4,000% to $ 200 million per year over the past decade, thanks to broad government support. Obama and Trump, Dreier said.
However, the challenges of spotting these potential planet killers are daunting. Terrestrial telescopes have limited range, objects approaching the direction of the sun cannot be seen, many asteroids reflect almost no light, and all of them travel at ridiculous speeds – 43,000 mph or 12 miles per second, in mean.
Moreover, not all are local. In 2017, astronomers spied on the first major visitor from outside the solar system, a 400-meter cigar-shaped weirdo called Oumuamua that looped around the sun at a blazing speed of 196,000 mph on its way to the return to interstellar space.
NASA is planning further testing of its trajectory modification techniques once it has data from the destruction of DART at Dimorphos, assuming the mission is successful.
Another idea under consideration is a “gravity tractor”, the concept being to attach a spacecraft to an asteroid to enlarge its mass and slowly change its orbit.
Still, observation is essential to prevent a repeat of the fate that befell the dinosaurs. NASA and other scientists suffer from the loss last year of the Arecibo Observatory in Puerto Rico, which played a key role in radar assessments of near-Earth objects, helping researchers determine their size and orbits . According to Johnson, the Earth Defender at NASA: “The key to planetary defense is to find them long before they pose a threat of impact.
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