Winston
Lorenzo von Matterhorn
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DART: Double Asteroid Redirection Test
https://dart.jhuapl.edu/Mission/index.php
Space scientists have big plans to avert an asteroid apocalypse
We're finally getting serious about planetary defense
6 Apr 2018
https://www.nbcnews.com/mach/scienc...ig-plans-avert-asteroid-apocalypse-ncna863106
...the next step in planetary defense is already underway at Johns Hopkins Universitys Applied Physics Lab. There, a team is developing a mission called the Double Asteroid Redirection Test, or DART, which is scheduled to launch around 2020. Its the first real-world embodiment of the HAMMER concept.
The 1,100-pound DART craft has thrusters, a camera, navigation software, and thats about it. Its design can be simple because its job is simple: find an asteroid and fly into it at full speed. Such a device is technically known as a kinetic impactor, but you can think of it as a battering ram in space.
We think we understand the physics of asteroid deflection in theory, but weve never performed an experiment at the right scale, says the Applied Physics Lab's Andy Rivkin, lead investigator for the DART mission. This is a dress rehearsal for a kinetic impactor-style of asteroid deflection.
The target set to be rammed is a double asteroid named Didymos. DART will go after the smaller of the two nearby space rocks, a 500-foot-wide rock nicknamed Didymoon. When the spacecraft reaches Didymoon, it will smash into it at 13,000 miles per hour. After the collision, DART will be destroyed but astronomers on Earth will watch to see exactly how Didymoon is changed and moved by the impact.
The DART data will be especially useful, Rivkin says, because Didymoon is believed to be what planetary scientists term a rubble pile more an assemblage of small rocks than a single big one. Its hard to know how such objects will react to a directed impact without running the experiment.
DART will also be the first planned visit to a binary asteroid, Rivkin says. Deflecting a double asteroid will be more complicated than dealing with a single incoming body. Soon well know more about how to do it.
If a 500-foot-wide asteroid like Didymoon were on a collision course with Earth, Rivkin estimates that two or three DART-like battering rams could be enough to shove it aside provided we had several years of advance warning. If we had to act quickly to deflect an incoming space rock, we would need a lot more force to avert a collision.
The very best thing that can be done to prepare for the potential impact of any-sized asteroid is to find it as far ahead of the impact day as our capabilities allow, says Lindley Johnson, NASAs planetary defense officer.
Johnson cites the daunting NASA estimates: There are roughly 25,000 Didymoon-scale asteroids, 230,000 asteroids in the 150-foot range, and millions more of diameters of 100 feet or less. So far, astronomers believe theyve found about two-thirds of the large ones, 5 percent of the medium ones, and essentially none of the small fry.
Even the little ones could pack a mighty punch. If a mansion-size stone were to hit Earth over open ocean or remote countryside, it might cause little damage, Johnson says. If it struck a city or even near one, however, it would bring widespread death and destruction. And smaller rocks are generally unseen until they are right upon us.
In short-warning scenarios, kinetic impactors like DART would not be enough. Therefore, the HAMMER study explored the use of nuclear warheads, just as in movies like "Armageddon." Nukes pack a bigger wallop and allow more precision, since we can adjust exactly how close they are to the asteroid when they explode.
For obvious political reasons, nobody is about to conduct a nuclear test strike on an asteroid. But OSIRIS-REx and DART will vastly increase the storehouse of data needed to turn the HAMMER studies into a real mission (even a nuclear one), if and when the need arises. After a long period of stinginess, Congress is also allotting more funding for asteroid surveys, increasing the likelihood that well have enough warning to make nukes unnecessary anyway.
It seems that the world is finally embracing an argument that planetary-defense advocates like Rivkin have been making for years: The asteroid threat is unique. Its the only natural disaster that can be predicted and averted.
https://dart.jhuapl.edu/Mission/index.php
Space scientists have big plans to avert an asteroid apocalypse
We're finally getting serious about planetary defense
6 Apr 2018
https://www.nbcnews.com/mach/scienc...ig-plans-avert-asteroid-apocalypse-ncna863106
...the next step in planetary defense is already underway at Johns Hopkins Universitys Applied Physics Lab. There, a team is developing a mission called the Double Asteroid Redirection Test, or DART, which is scheduled to launch around 2020. Its the first real-world embodiment of the HAMMER concept.
The 1,100-pound DART craft has thrusters, a camera, navigation software, and thats about it. Its design can be simple because its job is simple: find an asteroid and fly into it at full speed. Such a device is technically known as a kinetic impactor, but you can think of it as a battering ram in space.
We think we understand the physics of asteroid deflection in theory, but weve never performed an experiment at the right scale, says the Applied Physics Lab's Andy Rivkin, lead investigator for the DART mission. This is a dress rehearsal for a kinetic impactor-style of asteroid deflection.
The target set to be rammed is a double asteroid named Didymos. DART will go after the smaller of the two nearby space rocks, a 500-foot-wide rock nicknamed Didymoon. When the spacecraft reaches Didymoon, it will smash into it at 13,000 miles per hour. After the collision, DART will be destroyed but astronomers on Earth will watch to see exactly how Didymoon is changed and moved by the impact.
The DART data will be especially useful, Rivkin says, because Didymoon is believed to be what planetary scientists term a rubble pile more an assemblage of small rocks than a single big one. Its hard to know how such objects will react to a directed impact without running the experiment.
DART will also be the first planned visit to a binary asteroid, Rivkin says. Deflecting a double asteroid will be more complicated than dealing with a single incoming body. Soon well know more about how to do it.
If a 500-foot-wide asteroid like Didymoon were on a collision course with Earth, Rivkin estimates that two or three DART-like battering rams could be enough to shove it aside provided we had several years of advance warning. If we had to act quickly to deflect an incoming space rock, we would need a lot more force to avert a collision.
The very best thing that can be done to prepare for the potential impact of any-sized asteroid is to find it as far ahead of the impact day as our capabilities allow, says Lindley Johnson, NASAs planetary defense officer.
Johnson cites the daunting NASA estimates: There are roughly 25,000 Didymoon-scale asteroids, 230,000 asteroids in the 150-foot range, and millions more of diameters of 100 feet or less. So far, astronomers believe theyve found about two-thirds of the large ones, 5 percent of the medium ones, and essentially none of the small fry.
Even the little ones could pack a mighty punch. If a mansion-size stone were to hit Earth over open ocean or remote countryside, it might cause little damage, Johnson says. If it struck a city or even near one, however, it would bring widespread death and destruction. And smaller rocks are generally unseen until they are right upon us.
In short-warning scenarios, kinetic impactors like DART would not be enough. Therefore, the HAMMER study explored the use of nuclear warheads, just as in movies like "Armageddon." Nukes pack a bigger wallop and allow more precision, since we can adjust exactly how close they are to the asteroid when they explode.
For obvious political reasons, nobody is about to conduct a nuclear test strike on an asteroid. But OSIRIS-REx and DART will vastly increase the storehouse of data needed to turn the HAMMER studies into a real mission (even a nuclear one), if and when the need arises. After a long period of stinginess, Congress is also allotting more funding for asteroid surveys, increasing the likelihood that well have enough warning to make nukes unnecessary anyway.
It seems that the world is finally embracing an argument that planetary-defense advocates like Rivkin have been making for years: The asteroid threat is unique. Its the only natural disaster that can be predicted and averted.
