When NASA’s Double Asteroid Redirection Test (DART) collides with the small asteroid Demorphos, it will be our first attempt to demonstrate our ability to distract from dangerous incoming asteroids.
For decades, scholars around the world have been clear the skysearching for Potentially dangerous asteroids close to the ground. And as astronomers discover nearby Earth, asteroids In greater numbers than ever, attention is now turning towards how we can protect a land An asteroid must be discovered on a collision course. One technique is brute force, tested, Arrow It will collide with the 560-foot-wide (170-meter) Dimorphos at 7:14 p.m. EDT (2314 GMT) on September 26.
Demorphos is a member of a binary system with another asteroid, which is 2,600 feet (780 m) across. Didymus, making it the ideal target for measuring our deviation capabilities. DART’s so calledkinetic effect“It will change Demorphos’ orbit around Didymus, and because the two rocks are bound by gravity, there is no chance that the collision will accidentally push Demorphos through space.
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The experiment represents a change of pace for NASA, which has so far focused our spacecraft on science. However, according to Lindley Johnson, director of NASA’s Planetary Defense Coordination Office, the DART mission does not mean a change in policy thinking about dangerous objects, but rather a continuation of the work that has been done so far.
“Our charter from the start was not just to find asteroids, but to work on technology and techniques that could be used to deflect an asteroid off the collision course, if we ever find one,” he told Space.com. “DART is just a first test of what we see as an ongoing program.”
The roots of DART go back 20 years, when scientists at the European Space Agency looked at a kinetic probe mission called ‘Don Quijote’ (named after the knight in the famous Spanish novel). Although this particular mission was never achieved, in 2011 representatives from NASA and the European Space Agency discussed a possible joint aberration mission called AIM (Asteroid Impact Mission). This evolved into two independent but related missions: DART and the European Space Agency Hera’s missionwhich will follow DART, will visit Didymus and Demorphos in 2026 to view the impacts of the collision and conduct a scientific study of the double asteroid system.
If DART proves successful, planetary scientists view it as just that The beginning of our efforts To learn how to defend Earth from dangerous asteroids.
“We will certainly be looking to do tests in the future, whether it’s against a different type of asteroid, or to test another technology, like gravity,” Johnson said. The gravity tractor involves parking a large spacecraft next to an asteroid. The spacecraft, despite its small size compared to the asteroid, will have enough gravity to pull the asteroid toward it. release ion driveIn theory, the tractor would be able to pull the asteroid away from the Earth’s collision course.
Alternatively, thrust from an ion engine could push a small asteroid away from Earth. Or, solar reflectors placed on the surface of an asteroid could use sunlight to push space rocks away.
“There are a lot of ideas,” Johnson said.
However, while these deflection methods should work for smaller asteroids, deflection of larger asteroids takes a bigger punch. Being able to deflect an asteroid 0.6 miles (1 kilometer) wide would be “the dream,” according to Patrick Michel, a scientist at the French National Center for Scientific Research (CNRS) and the principal investigator on the HERA mission.
But he doubts we can deflect such a large asteroid using only a kinetic collider. “I don’t think that’s going to work because it’s so big,” he told Space.com.
So what might work against a larger asteroid? “We have a threshold in size where we have to mention the ‘bad word’: nuclear,” Michel said. “So much energy would be required to move a kilometer-sized asteroid that only a nuclear device could provide. The good thing is that we know about all the objects that are approximately one kilometer long and there is nothing that threatens us, at least for the next century. “
In theory, it gives us time, although it’s possible that an asteroid could be detected on a collision course, given that there are still a large number of such space rocks to find.
Astronomers expect that there are about 25,000 large objects crossing the Earth’s orbit. Of those over 0.6 miles (1 kilometer) in diameter that could threaten civilization if affected, about 97% have been discovered. For smaller ones, 460 feet (140 meters) across or larger and this can be significant Regional damage If it hits the ground, an estimated 42% have been found so far. None have been found on a collision course with Earth, at least not in the next century or so.
Scientists are still researching, with numerous terrestrial and space-based observatories contributing. The Pan-STARRS telescopes in Hawaii and the Catalina Sky Survey in Arizona were both funded by NASA to conduct searches for near-Earth asteroids, and Vera C Robin Observatory In Chile it will also play its part when it begins its scientific operations later this decade. In space, NASA Niways Mission – A new target given to the ancient large-scale infrared exploration spacecraft, drove the charge, finding thousands of asteroids.
Together, these searches now find an average of about 500 large near-Earth objects (NEOs) each year, According to NASA. But of the 25,000 suspected asteroids near Earth that are over 460 feet in height, only about 10,000 . selected So far, which means that at the current rate of discovery, it will take another 30 years to find them all.
In an effort to speed things up, NASA plans to launch NEO Surveyor’s mission No later than 2026. As an infrared space telescope, the NEO Surveyor will search for and characterize all asteroids and dangerous comets larger than 460 feet and venturing within 30 million miles (50 million kilometers) of Earth.
“NEO Surveyor is designed to find the remaining groups of asteroids within 10 years,” Johnson said.
And although DART is the first mission to try to divert an asteroid, space agencies around the world have been visit asteroids over the years. NASA’s NEARShoemaker mission visited and landed on the near-Earth asteroid Eros in 2001, JAXA’s Hayabusa and Hayabusa 2 return sample Missions that visited near-Earth asteroids Itokawa And the Ryugu. NASA agency Osiris Rex The mission is currently bringing home samples from an asteroid benoand, of course, HERA will join the ranks after its launch in 2024. These missions characterize different types of near-Earth asteroids and determine their composition and internal structure, all of which help determine how well the deflection missions will be successful.
For now, however, all eyes are on DART and her encounter with Didymos and Dimorphos on September 26th. If the mission works as planned – and that’s still a big “if” – it will give us confidence that humans have a viable way to protect the Earth.
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