NASA Smashes Spacecraft Into an Asteroid: What’s the Plan?

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In a world where no problem is too big and no challenge too small, NASA continues to find ways to make its space exploration programs even more challenging. And sometimes, that means smashing things together with an asteroid. In another recent example of “bigger is better” thinking, the space agency recently announced plans to crash its Double Asteroid Redentor (DART) spacecraft into the asteroid Didymos measuring about half a mile in diameter. The DART mission was proposed as part of the Asteroid Initiative, which is led by John Holdren, President Obama’s Science Advisor. The initiative proposes a “set of activities and policies to understand, deter, and prevent asteroid threats to human populations and our common assets.” If this all sounds a little out there for your average space program, you’re not alone in your thinking.

What Is the Asteroid Initiative?

NASA plans to put astronauts on an asteroid by 2021. That’s the deadline for a program known as the Asteroid Redirect Mission, or ARM. The goal of ARM is to test the capabilities needed to divert an asteroid that threatens Earth. In order to do this, the space agency must first find an asteroid to study and redirect. The mission to find and redirect an asteroid will begin with the launch of the Double Asteroid Redirection Test (DART) spacecraft in 2021. DART will reach the asteroid Didymos in 2024, where it will break apart.

Why Smash an Asteroid With a Spacecraft?

NASA’s asteroid mission is designed to test technology that could be used to divert a potential killer asteroid. To do that, the agency is going to smash a spacecraft into a pair of asteroids that will be relatively close to Earth in 2022. Didymos is a binary asteroid system, which means it consists of two rocks

that orbit around each other. One of those rocks is around half a mile in diameter, while the other is only around 130 feet in diameter. Didymos is a great choice for the ARM mission because it has a relatively large and visible asteroid. The larger asteroid makes it easier to hit. It’s visible because it has a very large, visible rock.

Will This Help Prevent an Impact With Earth?

No, but it’s a good start. The goal of the Asteroid Initiative is to find all the potentially hazardous asteroids (PHAs) and determine which ones are the most threatening. NASA scientists plan to identify the most promising targets for the first mission to redirect an asteroid. The goal is to find an asteroid that is big enough to be a challenge yet small enough to be possible to divert. Didymos is a good candidate for this first mission because it’s about the right size for study and relatively close to Earth. The pace of the mission will be much faster than the usual pace of space missions. The plan calls for the DART mission to reach the asteroid and begin a detailed study between 2021 and 2024. DART will also spend some time pushing the smaller asteroid to a higher orbit.

What Will Happen When DART Breaks The Halo?

The first major step will be to break the orbit of the smaller asteroid and push it to a higher orbit around the large asteroid. The goal of this is to create a “halo” around the larger asteroid. The halo will be created by the smaller asteroid moving around the larger one in a very high, elliptical orbit. The elliptical orbit will intersect with the larger asteroid’s path around the sun. Approximately every five years, the smaller asteroid’s path will intersect with the larger one, causing the two to collide. The collisions will gradually move the larger asteroid off course, but very slowly.

Bottom line: Should we smash things together to prevent asteroid impacts?

Yes. While researchers can’t predict exactly where a PHA will impact, they can calculate where it is most likely to strike. By identifying all the locations where a PHA could strike, we can focus our efforts on the areas that will have the most devastating impacts. It makes sense to test our ability to divert an asteroid by actually trying to divert an asteroid. And, if we can learn how to divert an asteroid without actually destroying it, that’s even better! When it comes to defending Earth from asteroid impacts, the best approach is to stay ahead of the game. By finding and tracking asteroids, we give ourselves more time to plan for potential collisions.