Direct impact at 14000 mph or nukes? How to stop an asteroid to save Earth from Armageddon

  • NASA's DART mission to test deflecting an asteroid using "kinetic impact" with a spaceship is one way to defend Earth.

| Updated on: Sep 27 2022, 00:30 IST
NASA DART Mission in pics: Amazing Attack on Asteroid!
1/6 NASA with its Double Asteroid Redirection Test (DART) Mission spacecraft is all set to collide with a non-hazardous asteroid called Dimorphos in order to test planetary defence on Monday, September 26. The learnings from this asteroid attack will be used to protect Earth from asteroids that are heading for a collision with our planet. According to NASA, this will be the world's first mission to deflect an asteroid in space. NASA’s DART, built and managed by the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, will demonstrate and test asteroid deflection by kinetic impactor. (Bloomberg)
2/6 Dimorphos, the asteroid moonlet of Didymos poses no threat to Earth. The DART spacecraft had recently got its first look at Didymos, the double-asteroid system that includes its target, Dimorphos. It is being said that in 2024, the European Space Agency (ESA) will send a space probe to Dimorphos as part of the space mission HERA. The aim of the mission is to visually investigate the aftermath of the DART probe impact. (NASA )
3/6 When to watch: The live broadcast of the event will start on September 26 at 6 p.m., EDT. The spacecraft will impact its target asteroid at 7:14 p.m. EDT, while at 8:00 p.m. ET, the research organisation will host a post-impact press briefing. (AFP)
4/6 Where to watch: The historic collision can be watched live online as NASA will be broadcasting the same. NASA will broadcast the live coverage of DART’s impact with the asteroid Dimorphos on NASA TV and its several social media handles like Facebook, Twitter, and YouTube. (AFP)
5/6 About asteroids: According to NASA, More than 100 tons of dust and sand sized particles are bombarded towards Earth everyday. While, about once a year, an automobile-sized asteroid hits Earth's atmosphere, creates an impressive fireball, and burns up before reaching the surface. Every 2,000 years or so, a meteoroid the size of a football field hits Earth and causes significant damage to the area. Only once every few million years, an object large enough to threaten Earth's civilization comes along. Impact craters on Earth, the moon and other planetary bodies are evidence of these occurrences. (AP)
6/6 Space rocks smaller than about 25 meters (about 82 feet) will most likely burn up as they enter the Earth's atmosphere and cause little or no damage. By comparison, asteroids that populate the main asteroid belt between Mars and Jupiter, and pose no threat to Earth, can be as big as 940 kilometers (about 583 miles) across. (MINT_PRINT)
View all Images
NASA's DART probe at the Didymos system before impact with the asteroid Dimorphos, left. DART is expected to slam into it at 14000 mph. (AP)

NASA's DART mission to test deflecting an asteroid using "kinetic impact" with a spaceship is just one way to defend planet Earth from an approaching object -- and for now, the only method possible with current technology.

The operation is like playing billiards in space, using Newton's laws of motion to guide us.

If an asteroid threat to Earth were real, a mission might need to be launched a year or two in advance to take on a small asteroid, or decades ahead of projected impact for larger objects hundreds of kilometers in diameter that could prove catastrophic to the planet.

Or, a larger object might require hits with multiple spacecraft.

"This demonstration will start to add tools to our toolbox of methods that could be used in the future," said Lindley Johnson, NASA's planetary defense office, in a recent briefing.

Other proposed ideas have included a futuristic-sounding "gravity tractor," or a mission to blow up the hypothetical object with a nuclear weapon -- the method preferred by Hollywood.

- Gravity tractor -

Should an approaching object be detected early -- years or decades before it would hit Earth -- a spaceship could be sent to fly alongside it for long enough to divert its path via using the ship's gravitational pull, creating a so-called gravity tractor.

This method "has the virtue that the method of moving the asteroid is totally well understood -- it's gravity and we know how gravity works," Tom Statler, a DART program scientist at NASA said at a briefing last November when DART launched.

The mass of the spacecraft however would be a limiting factor -- and gravity tractors would be less effective for asteroids more than 500 meters in diameter, which are the very ones that pose the greatest threat.

In a 2017 paper, NASA engineers proposed a way to overcome this snag: by having the spacecraft scoop material from the asteroid to enhance its own mass, and thus, gravity.

But none of these concepts have been tried, and would need decades to build, launch and test.

- Nuclear detonation -

Another option: launching nuclear explosives to redirect or destroy an asteroid.

"This may be the only strategy that would be effective for the largest and most dangerous 'planet-killer' asteroids (more than one kilometer in diameter)," a NASA article on the subject says, adding such a strike might be useful as a "last resort" in case the other methods fail.

Watch NASA DART Mission Live on YouTube Below:

But these weapons are geopolitically controversial and technically banned from use in outer space.

Lori Glaze, NASA's planetary science division director said in a 2021 briefing that the agency believed the best way to deploy the weapons would be at a distance from an asteroid, in order to impart force on the object without blowing it into smaller pieces that could then multiply the threat to Earth.

A 2018 paper published in the "Journal of Experimental and Theoretical Physics" by Russian scientists looked at the direct detonation scenario.

E. Yu. Aristova and colleagues built miniature asteroid models and blasted them with lasers. Their experiments showed that blowing up a 200-meter asteroid would require a bomb 200 times as powerful as the one that exploded over Hiroshima in 1945.

They also said it would be most effective to drill into the asteroid, bury the bomb, then blow it up -- just like in the movie Armageddon.

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First Published Date: 27 Sep, 00:28 IST
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