Tech UPTechnologyAre we prepared to protect Earth from asteroids?

Are we prepared to protect Earth from asteroids?

NEO, written like this, with capital letters, is not the name of the messianic protagonist of the Matrix saga, but the acronym for a potentially apocalyptic threat: Near-Earth Objects . And we are not talking about objects in the form of “spatial-junk-that-floats-placidly”, but of the type “boulders-at-great-speed-that-as-they-crash-against-us-they-leave-us-facts -cinnamon”.

There are not a few asteroids and comets whose orbits pass close to Earth – of the 600,000 known asteroids in the Solar System, more than 16,000 are NEO – and can measure tens of kilometers. Do you remember the meteor that caused great damage and almost 1,500 injuries in Chelyabinsk (Russia) in February 2013? It exploded at an altitude of 20,000 meters and released an energy of 500 kilotons – 30 times higher than that of the Hiroshima nuclear bomb. Well, that object did not reach 20 meters in diameter. Imagine what an asteroid ten, a hundred or a thousand times larger would do.

How can we protect ourselves against these devastating sidereal stones? Is it really in our power to prevent an asteroid from extinguishing us or are we totally exposed to chance? Amy Mainzer, principal investigator for NASA’s asteroid hunting mission at the Reaction Propulsion Laboratory in Pasadena, California, believes the key lies in detecting threats well in advance to allow room for maneuver.

“If we find an object only a few days from impact, that greatly limits our options, so we have focused our efforts on locating NEOs when they are still very far from Earth, to give the maximum amount of reaction time and thus open. a broader range of mitigation possibilities, ”Mainzer said this week at the April meeting of the American Physical Society, where he explained the work being done by NASA’s Planetary Defense Coordination Office.

Black on black

How to spot potentially dangerous asteroids well in advance? Is not easy. It is a task similar to detecting a piece of coal in the middle of the night sky. “NEOs are inherently faint, almost imperceptible, because most of them are very small and very far from us,” Mainzer noted. Add to that the fact that some are as dark as printer toner, so trying to detect them against the black of space is very difficult. “

For all these reasons, Mainzer’s team has focused on detecting asteroids not by their visible light, but by their heat. Both asteroids and comets are heated by the Sun and therefore glow brightly at thermal (infrared) wavelengths. And that’s where the Near-Earth Object Wide-Field Infrared Explorer Telescope – NEOWISE, for its acronym in English – comes into play. “Thanks to the NEOWISE mission, we can detect objects regardless of their surface color and use them to measure their sizes and other properties,” Mainzer said.

Using this data, your team is able to get an idea of two critical aspects when developing a defensive strategy: the size and composition of the potentially dangerous NEO. Because one of the possible countermeasures consists of physically pushing the object to divert it from its collision course and, in order to calculate the energy required for this push, it is essential to know its mass, its volume and the materials of which it is formed. And if you choose to destroy it with a nuclear bomb, that data would be just as valuable.

Astronomers also believe that examining the composition of asteroids will help to understand how the Solar System formed. “These objects are interesting because some are believed to be as old as the original material that made up the Solar System,” Mainzer said. One of the things that we have discovered is that NEOs are very diverse in their composition. “

Mainzer was also willing to take advantage of advances in camera technology to aid in the search for NEO. “We are proposing to NASA a new telescope, the Near Earth Object Camera (NEOCam), to do a much more complete job of mapping the locations of asteroids and measuring their sizes,” he concluded.

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