On Friday, NASA announced plans to redirect the course of a small asteroid approaching earth, marking the first step in a planetary defense strategy intended to protect earth from the possibility of large asteroid strikes.
NASA’s plan involves using a “kinetic impactor” to change the course of an asteroid on its path so as to prevent it from crashing into the earth. Unlike the movie “Armageddon,” which saw a team of oil drillers working to blow an inbound asteroid apart, simply adjusting the course of an asteroid would be a much safer, and less complex solution.
The mission, called the Double Asteroid Redirection Test (DART), a joint effort between NASA and the Johns Hopkins Applied Physics Laboratory in Maryland, and has the potential to be the most important defense oriented project in human history. While most defensive measures involve protecting nations from one another, what NASA learns throughout the DART exercise could go on to save the entire planet, and human race, if a large asteroid is discovered on a collision course with earth.
“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,” said Lindley Johnson, planetary defense officer at NASA Headquarters in Washington. “This approval step advances the project toward an historic test with a non-threatening small asteroid.”
The asteroid NASA has set its sights on “is called Didymos — Greek for ‘twin’ — because it’s an asteroid binary system that consists of two bodies: Didymos A, about one-half mile (780 meters) in size, and a smaller asteroid orbiting it called Didymos B, about 530 feet (160 meters) in size. DART would impact only the smaller of the two bodies, Didymos B,” NASA wrote in a press release provided on Friday.
The Didymos asteroid system has been closely studied since 2003, and is expected to make a distant approach to Earth in 2022, and again in 2024. The primary (larger) body is of similar composition to asteroids found within our solar system that make up the most likely threats to continued life on our planet. The smaller body, Didymos B, is mostly unknown, but both asteroids are large enough to create what NASA refers to as “regional effects” were they to impact the earth.
“A binary asteroid is the perfect natural laboratory for this test,” said Tom Statler, program scientist for DART at NASA Headquarters. “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.”
NASA’s plan is to launch DART on an intercept path with the asteroid pair, then use its on-board autonomous targeting system to aim itself at the smaller of the two asteroids, Didymos B. The spacecraft, which is roughly the size of a refrigerator, would then accelerate directly at the asteroid at speeds reaching nine times that of an average bullet, approximately 3.7 miles per second, impacting it and causing it to shift its orbital trajectory.
The impact is not intended to literally push the large spatial body off course, so much as it hopes to merely change the speed of the asteroid by a mere fraction of its overall velocity, changing the path of the rock to an increasing degree over time and distance covered, much like a tiny shift in rifle placement can result in missing a target by feet at the end of a bullet’s flight path.
“DART is a critical step in demonstrating we can protect our planet from a future asteroid impact,” said Andy Cheng of The Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, the DART investigation co-lead. “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.”
Watch a short video that demonstrates the scale of the DART craft versus the asteroids below.
Image courtesy of NASA