Researchers are trying to save Earth from an asteroid apocalypse by using a new planetary defense technique called PI, short for "Pulverize it."
The detailed plan is described in a technical paper posted on the University of California, Santa Barbara (UCSB), Experimental Cosmology Group website. It was submitted to Advances in Space Research. The aim of the article is to break down large, potentially dangerous asteroids into hundreds of small pieces by launching an array of penetrator rods into the path of the asteroid.
Researchers wrote that the rods measure 6-10 feet in length (1.8-3 meters) and could contain explosives or nuclear weapons to explode an approaching asteroid.
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According to the authors, even though debris may cause damage to buildings and people below, it could still do so. This damage is negligible when compared to the impact of large asteroid. For example, the 19-meter wide meteor that struck Chelyabinsk in Russia in February 2013 at a force of approximately 30 Hiroshima bombs, was 62 feet across. The shockwaves that resulted from the explosion could have killed millions if it had struck a large city directly. However, the blast happened over a wide area, which caused damage and injuries, but not fatalities.
To make a cartoon analogy, one large asteroid is different from hundreds of smaller ones. "A 500-kilogram [1,100-pound] grand-piano being dropped on your head at a height one kilometer [or] 500 kgs of foam balls being dropped on you at the same height," Philip Lubin (both UCSB) wrote in a Scientific American editorial.
The PI plan would send dozens of spear-shaped "penetratorrods" straight into the path of an approaching asteroid, "pulverizing", and "pulverizing," the rock into hundreds. (Image credit: Alexander Cohen)
The threat of imminent doom
NASA monitors the movements of nearly 8,000 near-Earth asteroids that have diameters greater than 456 feet (140m). As the Chelyabinsk accident demonstrated, even smaller objects can pack a big punch.
Chelyabinsk's meteor caused so much destruction because astronomers couldn't predict it. The rock was smaller than most asteroids that space agencies usually track and shot directly at Earth from the direction the sun according to NASA.
The PI plan has one advantage: a rocket with penetrator rods can theoretically be launched in very short notice. Researchers said that this could happen even minutes before the object reaches Earth's atmosphere.
Researchers wrote in Scientific American that an impactor as large as the 20-meter-wide spacerock that fell over Chelyabinsk could be intercepted within 100 seconds of impact using a launcher similar the one used for intercontinental missiles.
The team stated that a rock as large as the 1,200-foot-wide (370-m) Apophis asteroid could be dealt with "10 days before striking Earth." SpaceX's Falcon 9 launcher, which uses existing rocket technology, could deploy the explosive rods in a region around an asteroid.
If these estimates are correct, the PI method will be a much more flexible plan for planet defense than NASA's current mission that alters the course of an asteroid near Earth by smashing a rocket into them. The Double Asteroid Redirection Test, also known as DART, will launch in November. However, it will take nearly a year before the test rocket reaches its target, the 525-foot-wide (160-m) moon of Didymos. The rocket impact should slow the moon's orbit enough to allow astronomers to assess whether the asteroid redirection works.
To prove PI viable, extensive testing would be required. This could include ground-based testing of fake asteroids and then moving on to space targets. No such tests are currently planned.
Scientists must be able to detect tiny near-Earth asteroids such as the Chelyabinsk Impactor before they enter our atmosphere. This is also key to the success of the method. This is also a work in process.
In Scientific American, the authors concluded that PI and other planetary defense methods would not offer optimal protection without a suitable early warning system. "PI is only one piece of the urgent puzzle. To properly protect Earth, we must open up more eyes to the sky."
Original publication on Live Science