On Monday, in what sounds like a scene from a sci-fi movie, NASA will slam a spacecraft into a distant asteroid to see if it can shift its orbit, all in an effort to test a way to protect Earth of any possible future threat. .
The good news is that there is no need to panic: the asteroid, which is part of a binary or two-body system, is not a threat to our planet, and there are no known ones that will at least during our way. the next 100 years. However, space agencies like the US National Aeronautics and Space Administration want to be prepared in case there is a threat.
NASA’s Double Asteroid Redirect Test (DART) is testing a way a spacecraft can push an asteroid on a collision course with Earth out of its orbit.
At 7:14 PM ET on Monday, the refrigerator-sized spacecraft will crash into Dimorphos, a moon orbiting its larger companion, Didymos, at about 6.6 km/s.
The goal is not to knock Dimorphos out of orbit, but to change its 12-hour orbit around Didymos by 10 minutes. That means scientists will know in about 12 hours if they were successful.
So why target a binary asteroid system instead of a single asteroid to see if you can change its orbit around the sun?
This image of light from the asteroid Didymos and its orbiting moon, Dimorphos, is a composite of 243 images taken by the Didymos Reconnaissance and Asteroid Camera for Optical Navigation (DRACO) on July 27. (NASA JPL DART Navigation Team)
“A binary system was perfect for this test,” said Mallory DeCoster, a senior scientist at Johns Hopkins University’s Applied Physics Laboratory in Maryland and part of the DART Impact Modeling Working Group.
For one thing, the size of Dimorphos, about 164 meters in diameter, is perfect for illustrating whether this would be an effective way to deflect asteroids that pose a threat to Earth. Didymos is 780 meters wide.
“But the other piece is that if we hit a single asteroid, to characterize whether we changed its orbit, we would have to wait until it completed its orbit around the sun, which could take many, many years.”
The other advantage is that the binary system is relatively close to us, astronomically speaking, only 11 million kilometers away.
Shooting gallery
NASA’s Center for Near-Earth Object Studies says that more than 90% of near-Earth objects (NEOs) more than a kilometer have already been discovered. But that doesn’t mean we’re out of the woods when it comes to potentially hazardous asteroids (PHAs).
In 2013, the Chelyabinsk asteroid, which was about 20 meters in diameter, exploded over parts of Russia, injuring about 1,000 people and serving as a reminder of how dangerous even a small asteroid can be.
In February 2013, a meteorite trail was seen over Chelyabinsk, Russia, a city near the Ural Mountains located about 1,500 kilometers east of Moscow. The Chelyabinsk asteroid, which was about 20 meters in diameter, exploded over parts of Russia and injured about 1,000 people. (Chelyabinsk.ru, Yekaterina Pustynnikova/The Associated Press)
Basically, Earth is flying through a shooting gallery in space. There are small pieces of debris that burn up in our atmosphere as meteors; of larger ones, like Chelyabinsk; and then even larger ones that can be catastrophic, all left over from the formation of our solar system.
That’s why space agencies like NASA and the European Space Agency have been trying to develop ways to deflect or boost a PHA so that its orbit changes and poses no threat to Earth.
Mike Daly, a professor at York University’s Lassonde School of Engineering in Toronto and a DART co-investigator, said one of the more popular concepts is to deflect asteroids before they become a real threat. But that means we have to give advance notice that one is headed our way.
“So the simplest method is what DART is doing, which is essentially taking a spacecraft at high speed and crashing it into the asteroid and using that transfer of energy from the spacecraft to the asteroid to move.” l,” he said. .
This infographic shows the potential effect of DART’s impact on Dimorphos’ orbit. (NASA/Johns Hopkins APL)
However, the science behind deflecting asteroids in this way is more than the combination of the spacecraft’s size and incredibly high speed, called a hypervelocity impact.
“In a hypervelocity impact, you induce this pressure wave on the target that makes a lot of new physics happen,” said Johns Hopkins University’s DeCoster.
“So what’s going to happen, or what we think is going to happen, is that the size of the spacecraft might not matter much. It might actually be: How does the asteroid respond to this pressure wave that’s induced because of the ‘hypervelocity impact? And we think it’s probably going to eject a lot of material in the form of ejecta. And that ejecta could have an important component in changing the orbit. They could emit so much ejecta that that piece could matter more than the energy incoming. of the spacecraft in changing its orbit.”
The DART team expects an onboard camera, called DRACO, to show the close approach and suddenly turn black, which would be indicative of an impact.
This map shows the 38 telescope facilities in space and around the world expected to observe the Didymos asteroid system in support of DART’s post-impact global observing campaign. The numerical figures in parentheses next to the telescope names indicate the size of the telescope. (NASA/Johns Hopkins APL/Nancy Chabot/Mike Halstad)
But there’s a laggard coming up behind DART, about three minutes: the Italian Space Agency’s Light Italian Cubesat for Imaging of Asteroids, or LICIACube. Their role is to photograph the impact, study the ejecta plume, and help determine the asteroid’s morphology, as they may be made of iron, rock, or simply clumps of rock held together by gravity.
As this is the first evidence of a form of planetary defense, scientists are eagerly awaiting not only the impact of the event itself, but what they will learn from it and, most importantly, what it may mean for to the future of protecting the Earth in the future. . Telescopes around the world will observe the event and collect tracking data.
“We’re really the first generation to be able to protect ourselves from these potentially catastrophic impacts,” said York University’s Daly. “And, you know, fortunately the really catastrophic ones don’t happen very often, but they could happen, and we’ve never been able to change our fate before. So I think it’s really up to us, given the potentially huge consequences of not paying attention and our ability to do so.”
The event will be broadcast on NASA TV, which is available online and through its app.