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Scientists try to model what would happen if Ryugu hit Earth

Ryugu's northen hemisphere
Ryugu’s northen hemisphere. The arrow marks the spot Hayabusa-2
gathered samples

Scientists, using the data and rock samples gathered by the Japanese probe Hayabusa-2, have attempted to predict what what would happen if the rubble-pile asteroid Ryugu hit the Earth.

Without diversion intervention, Tanaka explained, if the Ryugu asteroid was heading to Earth and entered the planet’s atmosphere at an angle of 45 degrees and at a speed of around 38,000 miles per hour (17 kilometers per second), the rubble pile asteroid would break up at an altitude of around 25 to 21 miles (40 to 35 km) over the surface of the planet.

This would result in an “airburst” similar to that seen over Russia in February 2013 when the Chelyabinsk meteor erupted at an altitude of around 19 miles (30 kilometers) over Earth. The result of the Chelyabinsk blast was a bright flash of light and an atmospheric blast equivalent to the detonation of 400–500 kilotons of TNT. This is as much as 33 times the energy released by the atomic bomb that devastated Hiroshima at the end of the Second World War.

The Chelyabinsk meteor caused about 1,500 injuries, mostly from people injured by glass thrown out by breaking windows when it suddenly and unexpectedly exploded during re-entry. With Ryugu this would not be a surprise, so these injuries could be reduced, though not eliminated. The damage and injuries from pieces that survived the breakup and hit the ground remains unknown because scientists don’t know how much of the asteroid would survive the break up.

Ryugu of course poses no threat, because it is not on a collision course with Earth. Whether an asteroid like Ryugu could be diverted however remains unknown, since any such diversion must not cause the asteroid to break apart as well.

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  • David Ross

    Hmm. Getting the asteroid to break up (temporarily) might actually work. The fragments would be scattered over a wider trail at point of entry into the atmosphere. More of it has a chance to burn up or bounce out.
    Downside: if Not-Ryugu is hosting a large iron boulder *inside* the rubble, there’s no telling where on Earth that hunk will strike.

  • Ray Van Dune

    Yes, I think it is way past time to challenge the old saw about not nuking an asteroid “because that would make it worse”!

  • pzatchok

    We need to find a way to very rapidly get a probe out to any incoming asteroid that might hit us just to see if its possible to do something about it in time.
    And the farther out the better,

  • Ray Van Dune

    pzatchok’s idea has merit. Perhaps a set of long-duration “classifier” probes to successively orbit multiple threatening asteroids and determine their composition. And the neighborhood of known threats might be a good place to look for smaller asteroids that we could not detect from Earth.

  • Max

    “Ryugu of course poses no threat, because it is not on a collision course with Earth”

    That’s before a sample return mission on a similar astroid malfunctions, Landing on the astroid in thrust mode and pushes it into a different orbit…

    Or a rogue nation does this on purpose, intending to insert the astroid in a lunar orbit for mining (because other nations have already staked out their claims) when miscalculation distorts the astroid and it all falls apart giving earth a set of rings…

    It would probably make a good sci-fi movie similar to deep impact.

  • MDN

    Something does not add up here. The Cheyablinsk meteorite is estimated to have been 18 meters in diameter whereas Ryugu is 900 meters in diameter. Yet they are estimating a similar sized event were Ryugu to hit Earth in a similar manner? I don’t think so. It seems to me a better comparison would be to the Tanguska event which is speculated to have been just a 60 meter asteroid, but a stony body, not a Rubble pile, and traveling twice as fast. That was a megatons class blast that devestated over 800 square miles. So I am very skeptical of the accuracy of this analysis.

  • Star Bird

    And how many times have they been predicting this Killer Asteroid stuff? and how many times have they been screwing around with the Doomsday Clock?

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