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Astronomie - NASA preps for Armageddon style asteroid threat — but with far less drama

20.01.2019

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Neil deGrasse Tyson once tweeted that, “Asteroids are nature’s way of asking, ‘How’s that space program coming along?’” Dr. Tyson was making a sly reference to an incident 65 million years ago, when a huge rock struck the Earth in the region of the Yucatan and wiped out the dinosaurs and much else.

The dinosaurs did not have a space program. However, human beings, who arose to dominate the Earth after the dinosaurs’ demise, do have one and therefore the ability to save themselves if another world-killing asteroid approaches.

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NASA will soon launch a probe to an asteroid to practice saving the world. Teslarati reports that sometime between December 2020 and June 2021, the space agency intends to launch a probe called Double Asteroid Redirection Test or DART. DART will journey to a double asteroid called Didymos, which consists of a rock that is half a mile across and a smaller object dubbed “Didymoon,” which is about 530 feet in diameter. DART will slam into Didymoon at 4 miles per second, the idea being to change its speed by a fraction of 1 percent.

The second part of the mission is the European Space Agency probe, Asteroid Impact and Deflection Assessment or AIDA, which is scheduled to launch in 2023. AIDA’s mission is to evaluate how DART changed the speed and direction of Didymoon. AIDA will also carry a pair of cubestats, tiny probes the size of briefcases, which will land on Didymos and Didymoon.

Hollywood depicts asteroid deflection as very exciting, dangerous operations. The 1998 film “Deep Impact” and its somewhat more scientifically inaccurate counterpart “Armageddon” involved storylines of astronaut crews venturing to killer asteroids or comets to blow them up with nuclear explosives. The problem is that blowing up a killer rock transforms one big rock into a cluster of smaller ones that will hit the Earth over a wider area. A better method is to nudge the asteroid ever so slightly, putting it on a different course.

NASA prefers to do asteroid deflection with a little less drama than in the movies. The science behind DART derives from the idea that if we know an asteroid will hit the Earth years in advance, even a small change of speed and direction will cause it to miss, instead.

The trick, of course, is to scan the heavens for Earth-approaching asteroids and to determine whether and when they will pose a threat. The Large Synoptic Survey Telescope will scan the skies for possible killer asteroids as part of its mission. The OSIRIS-REx probe, currently orbiting an asteroid named Bennu, will examine how solar radiation affects the asteroid’s path. Bennu may possibly strike the Earth in the 22nd century.

NASA plans to avoid the situation depicted in movies, in which killer asteroids are detected only a short time before they are scheduled to impact. The better approach is to scan the skies for any asteroids or comets that could become a threat, preferably decades in advance. Then NASA would be able to deal with the matter at leisure.

Asteroid deflection technology could also be useful for future space miners. If an asteroid with valuable minerals could be moved to a more accessible orbit, then robotic miners could extract those resources and take them to a processing facility to manufacture useful products. Asteroid deflection would become one of the keys to developing a space-based industrial revolution.

Indeed, according to CNET, future asteroid explorers may be propelled by steam. A probe would visit an asteroid or comet that contains water ice, mine it for fuel, and then move on to the next target. Unlike previous asteroid explorers, such as DAWN, this type of spacecraft would never run out of fuel but could fly indefinitely. Such spacecraft could not only be explorers, but guardians, ready to move to deflect a threatening asteroid at a moment’s notice. Guarding against asteroid strikes could be a mission for President Trump’s proposed Space Force.

Quelle: The Hill

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