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Dust collected from the surface of an ancient, peanut-shaped and “potentially dangerous” asteroid has revealed that some space rocks are much springier and harder to destroy than first thought – raising concerns about Earth’s long-term security.
Analysis of three tiny dust particles collected from the surface of the 500-meter-long debris pile asteroid Itokawa shows that the cosmic wanderer has survived in space for at least 4.2 billion years, despite numerous collisions. This means that not only are asteroids of the same type more likely to make contact with our planet, but hitting them is probably not the best way to deflect or destroy such space rocks.
A “giant cushion” in space
Debris piles are shattered former asteroids formed after gigantic impacts and are made up of rocks and boulders that are loosely gathered and held together by gravity. Typically, nearly half the volume of a debris-pile asteroid is empty space, making scientists curious about the shock-absorbing abilities of these space rocks. Now a new study, published Jan. 23 in the journal Proceedings of the National Academy of Sciences, has shown that heaps of space rock have survived for nearly as long as the solar system has existed.
Related: Why do asteroids and comets have such strange shapes?
“The massive impact that destroyed the Itokawa parent monolithic asteroid and formed Itokawa occurred at least 4.2 billion years ago. Such an astonishingly long survival time for an Itokawa-sized asteroid is attributed to the shock-absorbing nature of the debris pile material,” lead author Fred Jourdan, a geochemist at the University of Curtin in Perth, Australia, said in a statement. “In short, we found that Itokawa is like a giant space cushion and is very difficult to destroy.”
The dust samples were collected from Itokawa in 2005 during the Japan Space Agency’s Hayabusa-1 mission, which sent a probe on a 3.8 billion-mile (6 billion-kilometer) round trip to land on the asteroid — and the tiny grains of its scratching the surface before they were sure to bring them back to Earth in 2010.
To analyze the samples, the researchers used two methods. In the first, called electron backscatter diffraction, the scientists bombarded the dust grains with a beam of electrons, allowing the team to study the grains’ crystalline structure by the way the electrons were diffracted from their surfaces. The second method, argon-argon dating, fired another beam at the grains – this time from a laser – to release argon gas that revealed the age of the asteroid based on the extent of the gas’s radioactive decay.
The researchers found that Itokawa has been floating in space for eons, easily surviving single-boulder asteroids that have only predicted survival times of hundreds of thousands of years.
“We set out to answer whether debris-pile asteroids are shock-resistant or whether they shatter at the slightest blow,” said co-author Nick Timms, a geologist at the University of Curtin, in the statement. “Now that we’ve found that they can survive in the solar system for almost its entire history, they must be more common in the asteroid belt than previously thought, making it more likely that a large asteroid hurtling toward Earth will do so.” a heap of rubble.”
planetary protection
NASA tracks the locations and orbits of about 28,000 asteroids and tracks them with the Asteroid Terrestrial-impact Last Alert System (ATLAS), an array of four telescopes capable of performing a scan of the entire night sky every 24 hours. The space agency labels any space object that is within 120 million miles (193 million km) of Earth as a “near-Earth object” and classifies any large body within 4.65 million miles (7.5 million km) of our planet as “potentially dangerous”. “
If a debris-pile asteroid were to rush towards us, the researchers might say that understanding how the cairns differ from their solid cousins could allow humans to deploy better planetary defenses against them.
Space agencies around the world are already working on ways to deflect dangerous asteroids. On Sep 26, the Double Asteroid Redirection Test (DART) spacecraft redirected the harmless asteroid Dimorphos by blowing it off course and changing the asteroid’s orbit by 32 minutes in the first test of Earth’s planetary defense system.
However, this new research shows that simply throwing an asteroid off course isn’t always an option — especially with shock-absorbing asteroids from debris piles.
“If an asteroid is discovered too late for a kinetic collision, we may be able to use a more aggressive approach, such as “For example, use the shockwave from a nearby nuclear explosion to throw a debris-pile asteroid off course without destroying it,” Timms said.
This method has not yet been tested. Future research will be required to prove whether nuclear blast asteroid deflection is feasible.
