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A series of very strange memos arrived at the White House in the fall of 2017, detailing a potential nightmare scenario: an asteroid apparently on the right track to hit the Earth. But these notes were covered with bright red warnings, noting that they were only part of an exercise; Mankind had no other reasons than normal to fear the end of civilization.
The memos were part of a surreal and sophisticated exercise that allowed NASA and the scientific community to practice existential threat of an asteroid it seems to be on track to hit Earth – all based on a real asteroid. And now, the team involved in the drilling has released a final series of findings on the progress of the project and what humans can do to be better prepared for this potential apocalypse scenario.
"The most important thing was [that] This is the first time we are testing the entire system, including notification to the White House, "Vishnu Reddy, an expert in planetary defense at the University of California, told Space.com Arizona, co-author of the new document.Annual Lunar and Planetary Science Conference held at The Woodlands, Texas. "It was a truly fantastic experience for us to test with a real asteroid."
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In early 2017, scientists decided to conduct such an exercise. So they went looking for an asteroid, which was not really risky, but which would be close enough to produce realistic data on how a real risk could materialize. This would allow planetary defense specialists, who exclusively study the threat of asteroid impacts, to test their effectiveness. observation, evaluation and response procedures.
A rock of the called space 2012 TC4 adapt to the law. Upon the initial detection of this object in 2012, observations of his way through the solar system suggested that he would make a closer – but not dangerously close – approach to Earth in October 2017, although the researchers n & # 39; Have not clearly determined the route to follow.
This is so that the asteroid has acquired its guinea pig role for the end of the world as we know it.
"We knew it was not a threat … we wanted an exercise, but TC4 was a good candidate," said Michael Kelley, NASA scientist for the planetary defense program and co-author of the synthesis paper , during a presentation. at the same conference. "It was an asteroid whose orbit was slightly uncertain and which corresponded to the period we were looking for in this exercise, we knew it was there, we knew where to look in the sky, but we did not know exactly where to point the telescopes, so we would have to look a bit to try to find it. "
This research began in July 2017, when a team using the software Very large telescope in Chile started trying to spot TC4. They clung for good in August, when they expected it. A different telescope, Pan-STARRS in Hawaii, also separately proved that, if the scientists had not had the 2012 data, they would still have spotted the asteroid about two weeks before the closest approach to 2017.
As the TC4 drew closer, scientists turned telescopes around the world toward the object. First, they were trying to follow his path. Observers and orbital trajectory specialists worked together to update their expectations as to exactly where the rock would move, a key responsibility of planetary defense. As the situation evolved, the team relayed the data to government officials to explain how the situation would be handled in the real world.
The good news is that you have never heard of a big asteroid hitting the Earth in the fall of 2017. The most complex finding is that there was a time when the calculations of the team suggested that it was a real possibility, said Kelley. In short, on September 24th of this year, calculations gave TC4 a 180 chance to touch the Earth. "It's way below the threshold to trigger all the triggers of an emergency," Kelley said.
Fortunately, in just a few days this opportunity was missing. evaporated. Uncertainty, however, creates a risky situation, he added, because the team never wants to act recklessly and cause panic. But someone who does not follow the entire process could have taken the day's data out of context, intentionally or not.
"You have to be very, very careful when you have a lot of measurements coming in and you are waiting to see what fits the model and what does not fit the model," said Kelley. "You can come to a point where you draw the wrong conclusion if you stop at a certain point or if you just take a snapshot."
By the end of the exercise, the team had completely eliminated any likelihood of TC4's impact in the foreseeable future.
But scientists did not just predict the trajectory of the asteroid; they also wanted to collect as much data as possible about the rock itself. In particular, they looked at how it faded and brightened as he spun in the space. In the context of a potential impactor, this information is not only scientifically interesting. More than that, details on the rotation and composition of an asteroid can affect the potential disaster, affecting the amount of initial mass passing through the destructive atmosphere of the Earth.
Here too, things are a bit risky. The team had aligned a series of installations they wanted to use in advance, but fate intervened. Scientists had wanted to use the massive radio in Arecibo in Puerto Rico to bounce the light waves on the surface of the asteroid and see how they have recovered. But Hurricane Maria devastated the island just weeks before the asteroid approached it the most, and the telescope was not ready to help. Scientists had to rush into two other radio telescopes, Goldstone and Green Bank, to make up for the lack of Arecibo.
And the team had wanted to use NASA's infrared telescope center in Hawaii to better understand the composition of the object. The telescope had a three-night window to catch TC4. He observed the asteroid the first night and was put to another task the second. The third night, the electricity was cut off.
"It turns out that someone cut a tree and that it fell on a power line," Reddy said. "And so the fate of the world will end in [the hands of] a person with an ax in his hand trying to cut a tree at night. "
There is no reason to think that the same kind of commonplace problems would wait patiently until a real threat passes. "There are real problems that can arise even in an emergency," Kelley said. "The bad timing is still there."
Despite the difficulties encountered during the observations, scientists are rather satisfied with what they have learned about TC4. It appears to be very bright, about 33 feet (10 meters) in diameter, with an uneven jagged surface. "It could be a fragment of a very bright white rock in space," said Kelley. It seems to look like an unusual type of meteorite – a type that represents only 1% of the space rocks that we have here on Earth – called aubrites.
Now that TC4 results are published, the team is ready to apply the lessons learned from the exercise to a new exercise. This team has selected a different asteroid, still based on the orbital convenience of the object. "We can not program the asteroid[s]. We have to somehow wait for their cooperation, "said Kelley.
This exercise will have a smaller scale than that of TC4, its goal being only to learn as much as possible about space, even if scientists already have a good idea of what it's all about. .
"We know a lot, but we claim we do not know," said Reddy. "Imagine that this asteroid strikes us, say, in 15 or 20 years and this is the last flyby, the best flyby for which we can characterize it to know what to do in the next 15, 20 years before the impact. What can we learn? "
This type of preparation is not just about learning distant space rocks sailing through the solar system. It also means that you need to become familiar with deeply earthly and human factors, like being ready if someone cuts the wrong tree on the wrong day.
"This exercise was actually a good lesson from the reality of trying to do that too, in a practical sense," said Kelley. "Real world events affected the campaign, but we treated them and worked through it." And as a result, humans should be better prepared for the next approach.
"Fortunately, the fate of the Earth did not depend on it, so everything is fine," he said.
The project is described in a document published in March in the journal Icarus.
Email Meghan Bartels to [email protected] or follow her @meghanbartels. follow us on Twitter @Spacedotcom and on Facebook.
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