Post by Andrei Tchentchik on Jul 8, 2019 13:55:45 GMT 2
(.#235).- What if a 300-meter asteroid threatened to crash on Earth in 2027?
What if a 300-meter asteroid threatened to crash on Earth in 2027?
By Tristan Vey - Updated on the 02/05/2019 at 06:38
The experts of the 6th Conference on Global Defense are working this week on this imaginary but plausible disaster scenario and the measures that should be implemented to avoid a disastrous collision.
The situation is as follows: an asteroid measuring between 100 and 300 meters in diameter was detected at 50 million kilometers on March 29, 2019. Problem, it is heading straight for us at the vertiginous speed of 50,000 km / h. Its trajectory leaves one fearing a possible collision in 2027. The risk of impact is still low, about 1%, but the danger, him, is immense: the collision could generate a colossal energy of one billion tons TNT equivalent, or close 70,000 times the power of the Hiroshima bomb. That's twice as much as all the nuclear tests done in the world so far. To give an idea, if such an object fell on Paris, it is at least the entire Ile-de-France would be instantly annihilated. The consequences of such an event would obviously be global. The time is therefore serious. Can we do something to avoid disaster?
Rest assured, this scenario is perfectly imaginary. This is an exercise submitted to the 300 astronomers, scientists, engineers and emergency experts gathered since Monday in Washington DC (United States) for the 6th Biennial Conference on Global Defense. "This is the fourth time this type of exercise has been done," recalls Patrick Michel, an asteroid specialist at the Côte d'Azur Observatory. "It's a kind of role play. Every day, new data is brought to advance the scenario. Working groups are thinking about what to do next. It begins by establishing an observation program to refine the knowledge of the object and can lead to the definition of a space mission to try to deviate the object of its trajectory if the threat is confirmed.
In 2013, the experts failed to agree in time on the procedures to be implemented. The fictional asteroid had crashed to Marseille, destroying the Côte d'Azur ... The exercise may seem very virtual but the Chelyabinsk meteorite is here to remind us that the sky sometimes falls on our heads. On February 15, 2013, this stone of only 20 meters disintegrated 20 km from the ground, blowing tens of thousands of windows and wounding a thousand people. "We need to make sure people understand that it's not Hollywood or film," NASA boss Jim Bridenstine told the conference. "It's ultimately about protecting the only planet we know right now to welcome life, and it's the planet Earth. (...) The dinosaurs did not have a space program, it's a fact. But we have one and we have to use it. "
In fact, this role play makes it possible to think concretely about how to apprehend such an event, the probability of which remains very low. "This may be the least likely natural hazard, but it is also the most cataclysmic and the only one we can prevent," says Patrick Michel.
To give an idea, there falls an asteroid 20 meters every 60 years, one more than 140 meters every 10,000 years on average, one more than one kilometer every 750,000 years, and one more than 10 km every 100 million years (like the one that caused the disappearance of dinosaurs 66 million years ago). If objects of more than one km are well known and pose no threat for the next century, we have identified to date only about 20% of asteroids over 100 meters that cross the orbit of the Earth. Sometimes, we only detect them a few months or weeks before they brush against us ... The delay would then be too short to do anything other than launching an evacuation procedure. This is not obvious knowing that the fallout area remains very uncertain even a few days before the impact (several hundred kilometers of margin of error).
New York on the line of possible impact
"This is the reason why NASA is working on a satellite, NEOCam, which would be dedicated to the systematic tracking of asteroids that pose a potential danger for the Earth," said Patrick Michel. Europe is also working on a network of ground-based telescopes, called FlyEye, for the same reasons. The first will be installed in Sicily. Others might follow in Spain or Chile.
But let's go back to the scenario presented this year to researchers. There are still eight years left to act. Preliminary calculations made it possible to define the line on which the asteroid could crash. It crosses the United States in particular, from the southwest to the northeast, through New York, and much of Africa. This is not trivial, because this is one of the questions raised in previous exercises: who should take responsibility for operations? Will the major space powers (mainly the United States, Russia, Europe, Japan and China) agree to cooperate whatever the endangered area? Under which leadership? Who would pay? "The consensus has so far been to not answer this question," says Romana Kofler of the UN Space Office.
The line on which the astride could crash according to the preliminary data unveiled during this exercise. Google Earth
At the operational level, the specialists imagine three main techniques: the gravitational tractor, the kinetic impactor and, as a last resort, the atomic bomb. The principle of the gravitational tractor is to send a heavy object (several tons) very close to the asteroid so that its mass disrupts little by little its orbit. This could only work with the smallest objects detected more than ten years in advance. In the case that concerns us here, it would probably be too late. The atomic strategy, the most violent, would be to detonate a bomb near the target. "The goal is not to spray the asteroid but to use the blast of the explosion and the X-rays emitted by the explosion to deflect it," says Patrick Michel. "It would really be a solution of last resort, if we could not launch anything earlier than a few months before the planned impact date."
Between the two, the kinetic technique is perhaps the most suitable. It consists of sending one or more objects at high speed on the asteroid to deviate slightly from its trajectory. Again, it should be done a little in advance, but a few years might be enough. NASA must test this idea on a small double asteroid in 2022 (this is the DART mission). Europe is working on a complementary mission, Hera, to study more precisely the impact made by the Americans and characterize the influence it has had on its trajectory. "It is very important that we have tested a technique at least once so that we are not completely deprived if the threat, even very unlikely, becomes real one day," said Patrick Michel. What no one wants, of course.
F I N .
What if a 300-meter asteroid threatened to crash on Earth in 2027?
By Tristan Vey - Updated on the 02/05/2019 at 06:38
The experts of the 6th Conference on Global Defense are working this week on this imaginary but plausible disaster scenario and the measures that should be implemented to avoid a disastrous collision.
The situation is as follows: an asteroid measuring between 100 and 300 meters in diameter was detected at 50 million kilometers on March 29, 2019. Problem, it is heading straight for us at the vertiginous speed of 50,000 km / h. Its trajectory leaves one fearing a possible collision in 2027. The risk of impact is still low, about 1%, but the danger, him, is immense: the collision could generate a colossal energy of one billion tons TNT equivalent, or close 70,000 times the power of the Hiroshima bomb. That's twice as much as all the nuclear tests done in the world so far. To give an idea, if such an object fell on Paris, it is at least the entire Ile-de-France would be instantly annihilated. The consequences of such an event would obviously be global. The time is therefore serious. Can we do something to avoid disaster?
Rest assured, this scenario is perfectly imaginary. This is an exercise submitted to the 300 astronomers, scientists, engineers and emergency experts gathered since Monday in Washington DC (United States) for the 6th Biennial Conference on Global Defense. "This is the fourth time this type of exercise has been done," recalls Patrick Michel, an asteroid specialist at the Côte d'Azur Observatory. "It's a kind of role play. Every day, new data is brought to advance the scenario. Working groups are thinking about what to do next. It begins by establishing an observation program to refine the knowledge of the object and can lead to the definition of a space mission to try to deviate the object of its trajectory if the threat is confirmed.
In 2013, the experts failed to agree in time on the procedures to be implemented. The fictional asteroid had crashed to Marseille, destroying the Côte d'Azur ... The exercise may seem very virtual but the Chelyabinsk meteorite is here to remind us that the sky sometimes falls on our heads. On February 15, 2013, this stone of only 20 meters disintegrated 20 km from the ground, blowing tens of thousands of windows and wounding a thousand people. "We need to make sure people understand that it's not Hollywood or film," NASA boss Jim Bridenstine told the conference. "It's ultimately about protecting the only planet we know right now to welcome life, and it's the planet Earth. (...) The dinosaurs did not have a space program, it's a fact. But we have one and we have to use it. "
In fact, this role play makes it possible to think concretely about how to apprehend such an event, the probability of which remains very low. "This may be the least likely natural hazard, but it is also the most cataclysmic and the only one we can prevent," says Patrick Michel.
To give an idea, there falls an asteroid 20 meters every 60 years, one more than 140 meters every 10,000 years on average, one more than one kilometer every 750,000 years, and one more than 10 km every 100 million years (like the one that caused the disappearance of dinosaurs 66 million years ago). If objects of more than one km are well known and pose no threat for the next century, we have identified to date only about 20% of asteroids over 100 meters that cross the orbit of the Earth. Sometimes, we only detect them a few months or weeks before they brush against us ... The delay would then be too short to do anything other than launching an evacuation procedure. This is not obvious knowing that the fallout area remains very uncertain even a few days before the impact (several hundred kilometers of margin of error).
New York on the line of possible impact
"This is the reason why NASA is working on a satellite, NEOCam, which would be dedicated to the systematic tracking of asteroids that pose a potential danger for the Earth," said Patrick Michel. Europe is also working on a network of ground-based telescopes, called FlyEye, for the same reasons. The first will be installed in Sicily. Others might follow in Spain or Chile.
But let's go back to the scenario presented this year to researchers. There are still eight years left to act. Preliminary calculations made it possible to define the line on which the asteroid could crash. It crosses the United States in particular, from the southwest to the northeast, through New York, and much of Africa. This is not trivial, because this is one of the questions raised in previous exercises: who should take responsibility for operations? Will the major space powers (mainly the United States, Russia, Europe, Japan and China) agree to cooperate whatever the endangered area? Under which leadership? Who would pay? "The consensus has so far been to not answer this question," says Romana Kofler of the UN Space Office.
The line on which the astride could crash according to the preliminary data unveiled during this exercise. Google Earth
At the operational level, the specialists imagine three main techniques: the gravitational tractor, the kinetic impactor and, as a last resort, the atomic bomb. The principle of the gravitational tractor is to send a heavy object (several tons) very close to the asteroid so that its mass disrupts little by little its orbit. This could only work with the smallest objects detected more than ten years in advance. In the case that concerns us here, it would probably be too late. The atomic strategy, the most violent, would be to detonate a bomb near the target. "The goal is not to spray the asteroid but to use the blast of the explosion and the X-rays emitted by the explosion to deflect it," says Patrick Michel. "It would really be a solution of last resort, if we could not launch anything earlier than a few months before the planned impact date."
Between the two, the kinetic technique is perhaps the most suitable. It consists of sending one or more objects at high speed on the asteroid to deviate slightly from its trajectory. Again, it should be done a little in advance, but a few years might be enough. NASA must test this idea on a small double asteroid in 2022 (this is the DART mission). Europe is working on a complementary mission, Hera, to study more precisely the impact made by the Americans and characterize the influence it has had on its trajectory. "It is very important that we have tested a technique at least once so that we are not completely deprived if the threat, even very unlikely, becomes real one day," said Patrick Michel. What no one wants, of course.
F I N .
