Methods for Protecting Earth against an Asteroid Strike

01Astronomers following asteroid activity in space estimate there is a very small chance an object large enough to destroy a whole city could strike Earth in 2032.

02But space agency officials say even if such an asteroid keeps heading on a path toward Earth, the world is now much better equipped to defend itself against such a threat.

03The American space agency NASA recently estimated there was a 3.1% chance that asteroid 2024 YR4 would hit Earth on December 22, 2032.

04That is the highest probability predicted for such a large space rock in modern times.

05Richard Moissel is head of the European Space Agency, or ESA, Planetary Defense Office.

06While recognizing the risk the asteroid could present, he told the French news agency AFP, people should not panic over such predictions.

07Astronomers have noted that the more data they gather, the odds of a direct asteroid hit are expected to keep rising over time.

08However, scientists say, at a certain point, the odds will likely drop down to zero.

09Moissel said he thinks it is important to remember that even in the unlikely event the probability the probability keeps rising to 100%, the world is not defenseless.

10Here are some methods currently being considered as defensive measures to keep humanity safe in case there is a real threat.

11Only one planetary defense method has been tried against an asteroid.

12In 2022, NASA's Double Asteroid Redirection Test, or DART, sent a spacecraft into the 160-meter-wide Demorphos asteroid.

13The effort successfully changed the asteroid's orbit around a larger space rock.

14Bruce Betts is chief scientist for the non-profit Planetary Society.

15He told AFP that space agencies could hit the 2024 YR-4 asteroid with several spacecrafts, observing how each one changed the path.

16The asteroid discovered in December is estimated to be 40 to 90 meters wide, about half the size of Demorphos.

17You have to take care not to overdo it, Moissel warned.

18He said this is because if a spacecraft only partially destroys an asteroid, it could send smaller pieces of the space rock heading toward Earth.

19A separate idea would involve sending a large spacecraft to fly alongside a threatening asteroid.

20The spacecraft would not touch the asteroid, but would use its gravitational force to pull it away from Earth.

21Moissel said another non-contact plan would put a spacecraft near the asteroid to eject a continuous flow of atoms to push the asteroid off course.

22Scientists have also considered painting one side of the asteroid white.

23They believe this could increase the light the object reflects to make it slowly change course.

24One idea is to use a nuclear weapon against a threatening asteroid.

25In laboratory tests, researchers found that X-rays from a nuclear blast could move a rock.

26But this is considered more of a plan for kilometers-wide asteroids, like the one that killed off the dinosaurs.

27And this method also carries the risk that a nuclear explosion could send additional pieces of the asteroid falling toward Earth.

28A similar method, but one considered less dangerous, would involve shooting laser beams from a spacecraft to destroy the side of an asteroid in an effort to push it away from Earth.

29Moissel said that if all else fails, at least the world will have a good idea where a threatening asteroid would strike.

30Since astronomers believe most asteroids would at most threaten to destroy one city, efforts could be organized to get people out of an area before a strike.

31Seven and a half years is a long time to prepare, Moissel added.

32He also noted that even with the rising odds involving 2024 YR-4, there is still about a 97% chance the asteroid will miss Earth.

33I'm Jill Robbins.

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