How scientists know we’re not going to get squashed by an asteroid

NASA uses telescopes to track asteroids and is developing technology to deflect potential impacts

This past year or so has been awful for a lot of reasons: a global pandemic, racial injustice, wildfires, a crazy active hurricane season and the list goes on -- but an asteroid crashing into Earth will not be the cherry on top of humanity’s punishment.

In a recent episode of the podcast “Space Curious,” planetary scientists helped us understand why this is.

They also explained how we know where asteroids are, and why we’re not all going to get squashed by one anytime soon.

In October, a NASA spacecraft called OSIRIS-REx collected a piece of a potentially hazardous asteroid to bring a sample back to Earth.

The U.S. space agency also has several other asteroid spacecraft missions in the works, and is not alone in its determination to better understand asteroids in order to deflect large space rocks -- but also to learn from these fossils of our solar system.

The spacecraft has been circling less than a mile from an asteroid called Bennu since December 2018, after launching nearly two years earlier from Cape Canaveral.

The 500-meter-wide asteroid was chosen for several reasons, explained Humberto Campins, a planetary scientist with the University of Central Florida, who is part of the OSIRIS-REx science team.

“The main reason we go to Bennu is because it is the most potentially hazardous asteroid,” Campins said. “It is not threatening Earth right now. But its orbit has the largest potential of evolving into one that would threaten Earth, and that would happen in about 160 years. So, if we have to deflect Bennu or if we have to deflect another asteroid, like Bennu, studying Bennu in detail will tell us a lot about how to do it.”

Besides the benefit to Earth’s security, Bennu is also full of clues to how our planet and others formed.

“It’s a primitive asteroid,” Campins said. “We think its surface or its material in general … has not been heated very much. And if it if it hasn’t been heated much, it preserves the same composition that it had when it formed about four and a half billion years ago.”

Beyond OSIRIS-REx, NASA is only ramping up its study of asteroids, including a robotic mission planned for the next year that will test technology that could, in theory, send an asteroid headed for Earth on another path.

The job of watching potential threats to the planet is up to NASA’s Planetary Defense Coordination Office. NASA funds ground-based telescopes to survey the sky to find and track near-Earth asteroids, which are asteroids that come within 30 million miles of Earth’s orbit.

“For an effective planetary defense, you must find any potential asteroid impact or with as much warning as possible,” said Andrea Riley, the mission program executive for NASA’s first planetary defense test mission known as DART, which stands for double asteroid redirection test.

“Should an asteroid be discovered that poses a future threat, we want to have a demonstrated mitigation capability. This is why the Dart mission is important,” Riley said.

The DART mission, slated to launch in 2021, will test using kinetic energy to push an asteroid changing its trajectory, becoming the first demonstration to change the motion of an asteroid in space.

Outside of sending spacecraft to asteroids and bringing samples home to better understand them, scientists all over the world are tracking and identifying new asteroids down on Earth.

Anne Virkki is the head of the planetary radar group at Arecibo Observatory in Puerto Rico, home to one of the largest and most powerful telescopes in the world.

Virkki said tiny asteroids come close to Earth every day but “we see them (as) shooting stars when they are disintegrating in the atmosphere.” However, an asteroid big enough to cause mass extinction has not hit the planet for at least about 66 million years. Historically speaking, that is extremely rare.

Larger asteroids do come close to Earth, but Virkki and others at ground observatories know when they are coming long before it happens.

“One of the closest calls will be in 2029, (with) asteroid Apophis,” Virkki said, adding it “will come about as close as some of the Earth-orbiting satellites.”

Apophis is expected to pass Earth in April 2029, but it is not expected to hit us, according Virkki.

“It’s not going to impact that (at the) time when it comes so close. So its orbit is very, very well constrained,” she said.

Campins said when someone reads about an asteroid headed for Earth, it’s a good idea to do some fact checking.

“We know that the internet is full of misinformation, right?” Campins said. “Go to a NASA website and find out what NASA is saying about it. NASA, the European Space Agency, there are a number of things, serious institutions that are not going to be prone to the hyperbole or exaggeration or downright lies.”

The chances of another mass-extinction event happening while we’re alive are so low, said Campins, you can ignore most of the clickbait.

“The chances of an asteroid hitting Earth and affecting us during our lifetime is extremely low,” Campins added. “It’s much lower -- much, much lower than winning the lottery, right? And you don’t count on winning the lottery to pay your rent.”

However, as a civilization, said Campins, we must study asteroids because we know one day it could happen.

“We know that devastating impacts have happened and will happen again, unless we stop the the next big one,” Campins said.

Space Curious is a podcast from WKMG and Graham Media Group that answers your intergalactic questions. Hosted by space reporter Emilee Speck, each episode is designed to inspire everyone, from the space curious to the space fanatics. Questions for the podcast can be submitted here.

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