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NASA reveals key facts about when dangerous asteroid Bennu would approach Earth

2021-08-12T11:23:21.044Z


Thanks to a visit from a NASA spacecraft, scientists have a much greater understanding of the asteroid, its next closest approaches to Earth, and whether it could impact our planet.


Asteroid Bennu could impact the Earth 0:44

(CNN) -

Bennu is one of the most dangerous known asteroids in our solar system.

Thanks to a visit from a NASA spacecraft, scientists have a much greater understanding of the asteroid, its next closest approaches to Earth, and whether it could impact our planet.

While NASA's OSIRIS-REx mission spent more than two years in orbit around Bennu, it was able to collect unprecedented information, as well as a sample that is currently returning to Earth.

The sample will arrive in September 2023.

Data collected by Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer allowed precise tracking of the asteroid's movements up to the year 2300, findings that reduce the uncertainties scientists had about the asteroid's future orbit.

The asteroid has a 1 in 1,750 chance of hitting Earth until 2300.

The asteroid will make its next closest approach to Earth in 2135. While Bennu won't get close enough to pose a threat to Earth, knowing its exact trajectory can help scientists better understand how our planet's gravity will change. the future orbit of the asteroid around the Sun. This could also affect Bennu's chances of hitting Earth after 2135.

Bennu will make its closest approach on September 24, 2182, with a 1 in 2,700 chance of hitting Earth that day.

Researchers agree that the risk of Bennu impacting Earth is low, and NASA will continue to monitor the asteroid's orbit for years to come.

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  • Check out the last image the Osiris-REx spacecraft took of the asteroid Bennu after it took off

A study based on the findings published Wednesday in the journal

Icarus

.

"NASA's Planetary Defense mission is to find and monitor asteroids and comets that can get close to Earth and pose a danger to our planet," said Kelly Fast, manager of the Near Earth Object Observation Program at headquarters. from NASA in Washington in a statement.

"We carry out this effort through ongoing astronomical studies that collect data to discover previously unknown objects and refine our orbital models for them. The OSIRIS-REx mission has provided an extraordinary opportunity to refine and test these models, helping us better predict in what point will Bennu be when it approaches Earth in more than a century. "

These are the new images of the asteroid Bennu 0:35

Study of an asteroid up close

The OSIRIS-REx mission reached Bennu in December 2018 and departed from there earlier this year on May 10, loaded with the sample it collected from the asteroid's surface.

Even though the spacecraft is a couple of years away from returning to Earth, it has been sending data that reveals what it learned about Bennu the entire time.

This allowed scientists to learn that it is a spinning top-shaped debris asteroid, made up of rocks held together by gravity.

It is approximately 500 meters wide.

"The OSIRIS-REx data gives us much more precise information, we can test the limits of our models and calculate the future trajectory of Bennu with a high degree of certainty up to 2135," said study lead author Davide Farnocchia, a scientist at NASA's Center for Near Earth Object Studies, in a statement.

"We have never before modeled the trajectory of an asteroid with this precision."

The Center for Near Earth Object Studies, based at the Jet Propulsion Laboratory in Pasadena, California, can use asteroid data to calculate their trajectories, predict their future motion, and assess whether or not there is a possibility of an impact. .

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The orbits of asteroids around the Sun change over time, and the smallest things can change them.

Specifically, the researchers wanted to determine whether Bennu will experience a "gravitational keyhole" during its first close approach to Earth in 2135. A gravitational keyhole is a small region of space where a planet's gravity can alter the orbit of a planet. passing asteroid.

If Bennu passes through one of these at a certain time due to Earth's gravity, it could put Bennu in the course of a future impact with our planet.

If Bennu passes through a gravitational keyhole, "then Earth's gravity would modify Bennu's motion just enough to put it on a collision path at a later date in the 22nd century," Farnocchia said.

Before this study, scientists were concerned that Bennu might have 26 potential gravitational locks to pass through.

Now, they only care about two of them.

"But we must bear in mind that the probability of impact, in general, is very small," Farnocchia said.

"In fact, there is a 99.94% probability that there is no impact trajectory. Therefore, there is no particular cause for concern."

Bennu in motion

Heat from the Sun can cause something called the Yarkovsky effect in asteroids. As asteroids orbit the Sun, they repeatedly heat up and cool down as they rotate. As the asteroid rotates through this temperature change, it releases energy and the asteroid receives a small push.

"The Yarkovsky effect will act on all asteroids of all sizes, and although it has been measured from afar for a small fraction of the asteroid population, OSIRIS-REx gave us the first opportunity to measure it in detail as Bennu traveled around the Sun." said study co-author Steve Chesley, a senior research scientist at NASA's Jet Propulsion Laboratory, in a statement. "The effect on Bennu is equivalent to the weight of three grapes constantly acting on the asteroid; miniscule, yes, but significant in determining Bennu's future impact possibilities for decades and centuries to come."

Other forces can alter the motion of asteroids, including the gravity of the Sun, other planets, moons, and other asteroids.

Dust in the solar system and the charged stream of solar particles, called the solar wind, can also affect Bennu's orbit.

And during the OSIRIS-REx mission, the team was surprised to observe Bennu's surface expelling particles into space, which could also play a role.

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While the goal of the mission was to collect a sample of Bennu and return it to Earth, the information obtained on near-Earth asteroids and better calculations of their orbits is crucial.

"The orbital data from this mission helped us better appreciate Bennu's impact potential over the next two centuries and our general understanding of potentially dangerous asteroids - an incredible result," said Dante Lauretta, OSIRIS-REx principal investigator and professor. from the University of Arizona in a statement.

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Source: cnnespanol

All news articles on 2021-08-12

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