NASA Plans to Deflect an Asteroid by Crashing a Satellite Into It
A NASA mission that will take place in the year 2022 will see the crashing of the Double Asteroid Redirection Test (DART) spacecraft into an asteroid binary system. The space agency essentially wants to study the effectiveness of the technique called kinetic impactor in diverting hazardous asteroids away from Earth.
The DART mission
An asteroid binary system known as the 65803 Didymos will have a distant approach to Earth in October 2022 and in 2024. The asteroid binary system is composed of a large body (780 meters in size) called Didymos A, which is orbited by Didymos B, a satellite or moon of a smaller size (160 meters). Didymos A was characterized as a rocky S-type object, similar to many asteroids. However, Didymos B has unknown compositions but has been determined to cause regional effects should it collide with Earth in the future.
Lindsey Johnson, a planetary defense officer at NASA HQ in Washington, explained how the DART mission will help in defending our planet from future asteroid threats.
"DART would be NASA’s first mission to demonstrate what’s known as the kinetic impactor technique - striking the asteroid to shift its orbit - to defend against a potential future asteroid impact. This approval step advances the project toward a historic test with a non-threatening small asteroid".
[Image Source: NASA/JHUAP]
The DART spacecraft will use an onboard autonomous targeting system to aim its crash at Dydimos B. It will collide with the small asteroid at a speed of 3.7 miles per second or 6 km per second, that is around 9 times faster than a shooting bullet. By observing its impact on Didymos B's orbit around Didymos A, scientists will be able to study the effectiveness of the kinetic impactor technique as an asteroid mitigation strategy. The DART spacecraft is small in proportion to Didymos B, only cited to be the size of a refrigerator.
The whole idea of the technique is to simply nudge off a threatening asteroid, which will eventually shift its route away from Earth. This means that the technique must be executed plenty of time before a predicted impact. By doing so, the kinetic impact will marginally change the total velocity of the asteroid and gradually alternate its spatial path.
Tom Statler, program scientist for DART at the NASA HQ, expressed that the DART mission on 65803 Didymos is the perfect test scenario for the technique.
"A binary asteroid is the perfect natural laboratory for this test. The fact that Didymos B is in orbit around Didymos A makes it easier to see the results of the impact, and ensures that the experiment doesn’t change the orbit of the pair around the sun".
Protecting the Earth
NASA is concentrating on the studies of asteroids that are large enough to cause global damage to our planet. Around 93% of those large asteroids (objects larger than 0.6 miles) have already been discovered. However, nobody has tested any technologies or strategies to deflect an asteroid's orbital path before in order to divert them away from Earth. Andy Cheng, DART investigation co-lead from the Johns Hopkins APL, said that the DART mission will enlighten scientists on how to protect Earth from any space threats.
"Since we don’t know that much about their internal structure or composition, we need to perform this experiment on a real asteroid. With DART, we can show how to protect Earth from an asteroid strike with a kinetic impactor by knocking the hazardous object into a different flight path that would not threaten the planet".
NASA has established the Planetary Defense Coordination Office last year, which is given the task of hunting, tracking, and characterizing celestial bodies that may be of potential threat to the Earth. They are also responsible for issuing warnings regarding potential impacts and to come up with an action plan and coordinate them with the American government. The space agency's funded telescopes and other equipment are currently on the hunt for such hazardous celestial objects. In the event of discovery, they will be programmed to track their orbits and study whether they will cause any threats to Earth or not.