Tag: Hitting

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Space agencies are keeping a close eye on a recently discovered asteroid that has a small chance of impacting Earth. Named 2024 YR4, the asteroid has a 1.2% chance of hitting our planet on December 22, 2032, the European Space Agency and NASA have found.

But that also means the space rock has a nearly 99% chance of safely passing by Earth in 2032, according to the ESA and NASA. Future observations of the asteroid will help scientists determine the likelihood of an impact.

The asteroid is estimated to be between 131 and 328 feet (40 and 100 meters) wide. Asteroids of this size impact Earth every few thousand years, and they can cause severe damage to local regions, according to the ESA.

The space rock has a “size range comparable to that of a large building,” said Dr. Paul Chodas, director for the Center for Near Earth Object Studies, or CNEOS, at NASA’s Jet Propulsion Laboratory in Pasadena, California. Chodas added that the actual size of the asteroid, which astronomers are trying to determine with follow-up observations using multiple telescopes, is currently highly uncertain.

“If the asteroid turns out to be on the large end of its estimated size range, the impact could produce blast damage as far as 50 kilometers (31 miles) from the impact site,” Chodas said. “But that’s in the unlikely event that it might impact at all. The potential for damage arises because of the incredibly high speed (about 17 kilometers per second, or 38,028 miles per hour) at which the asteroid would enter the atmosphere.”

The Asteroid Terrestrial-impact Last Alert System, or ATLAS, telescope located in Rio Hurtado, Chile, first spied the space rock on December 27. The telescope is one of the asteroid discovery programs funded by NASA to scan the sky in search of near-Earth asteroids, said Davide Farnocchia, navigation engineer at JPL and CNEOS.

“The discovery happened while the asteroid was in the Earth’s neighborhood, which made it bright enough to be detected,” Farnocchia said.

Automated asteroid warning systems sent out an alarm after determining the asteroid had a slim chance of impacting Earth in 2032, bumping it to the top of the ESA’s asteroid risk list and NASA’s automated Sentry risk list on December 31. Such lists include any known asteroids with a nonzero probability of colliding with Earth.

Since early January, astronomers have used the Magdalena Ridge Observatory in New Mexico, the Danish Telescope and the Very Large Telescope in Chile to track the asteroid, which is currently 28 million miles (45 million kilometers) from Earth and moving farther away over time, Farnocchia said. The observations can also help researchers refine their estimates of the asteroid’s size and trajectory.

As the asteroid moves away from Earth and becomes fainter, researchers will have to rely on larger telescopes to observe it. The celestial object should be visible through early April, and as it continues on its orbit around the sun, it won’t return to Earth’s vicinity until 2028, Farnocchia said.

If 2024 YR4 disappears from view before space agencies can entirely rule out any chance of impact, the space rock will remain on the risk list until it’s back in view in 2028.

“Using the available tracking data, we can predict the future position of an asteroid,” Farnocchia said. “The longer we track an asteroid, the more precise the prediction. As we collect additional data, the uncertainty in the position of 2024 YR4 in 2032 will decrease. Given that the impact probability is only 1%, it is 99% likely that the Earth will eventually fall outside the swath of possible positions and that the probability would fall to zero.”

It’s not uncommon for an asteroid’s impact probability to rise shortly after its discovery before that probability drops to zero after scientists learn more about its size and trajectory, according to the European Space Agency.

NASA and the ESA regularly track thousands of near-Earth asteroids, but depending on the size, they are not always easy to spot. But improvements in asteroid survey technology, and future asteroid-spotting missions, could detect the space rocks astronomers haven’t been able to see in the past. Currently, there are no other known large asteroids that have more than a 1% chance of impacting Earth, according to NASA.

Two international asteroid response groups endorsed by the United Nations — the International Asteroid Warning Network, chaired by NASA, and the Space Mission Planning Advisory Group, chaired by ESA — have activated in response to the threat level.

The International Asteroid Warning Network is responsible for coordinating the organizations involved in tracking and characterizing the details of the asteroid — and if necessary, developing strategies to assess the consequences of an impact.

Meanwhile, the Space Mission Planning Advisory Group, currently convening in an already-planned meeting in Vienna through next week, will provide recommendations and evaluate options for how to mitigate a potential impact if the asteroid remains a threat. Mitigation tactics include deflecting the asteroid in space or evacuating potentially impacted regions on the ground, Farnocchia said.

NASA carried out the Double Asteroid Redirection Test, called the DART mission, in September 2022 to assess the effectiveness of asteroid deflection technology. The agency wanted to see whether a kinetic impact — such as intentionally crashing a spacecraft into an asteroid at 13,645 miles per hour (6.1 kilometers per second) — would be enough to change the motion of a celestial object in space.

The DART spacecraft successfully changed the way a tiny asteroid called Dimorphos moves, shifting the moonlet asteroid’s orbital period — or how long it takes to make a single revolution around a larger space rock called Didymos — by about 32 minutes.

Neither Dimorphos nor Didymos poses a danger to Earth. Still, the double-asteroid system was a perfect target on which to test deflection technology because Dimorphos’ size is comparable to asteroids that could threaten our planet.

Now, an ESA mission called Hera is on its way to assess the aftermath of the DART impact to determine whether the collision merely left behind a crater or if the spacecraft’s momentum completely reshaped Dimorphos. Both agencies see the mission as a necessary step to understand the final outcome of DART’s deflection test. Measuring DART’s efficiency is crucial in case a similar strategy may need to be used against an asteroid on a collision course with Earth in the future.

“If 2024 YR4 remained a threat at the end of the current observing window, mitigation measures might be considered,” Farnocchia said. “But talk of mitigation is premature. The priority right now is to keep observing 2024 YR4 and reduce its positional uncertainties in 2032, since this is likely to rule out the impact.”