Despite Hollywood's depictions in the twin disaster movies Deep Impact and Armageddon—scientists have little grasp on how to actually handle a comet or asteroid hurdling toward Earth. And NASA researcher Dr. Joseph Nuth is concerned, writes Alan Yuhas at The Guardian.

Nuth recently broached the subject at the annual meeting of the American Geophysical Union in San Francisco. The problem, he says, is not detecting the potential threats, it's what we do once we spot a planet-destroyer.

Over the past year, our detection capabilities have vastly improved. In January 2016, NASA established a Planetary Defense Office to lead the effort in detecting incoming space rocks. And a new computer program called SCOUT, which entered a testing phase this past October, has already bolstered the early warning system.

A plan of what to do with these warnings, however, is lacking. While asteroids are typically slow moving, allowing years or even decades for us to respond, a fast-moving comet could make it to our home world just 18 months after being spotted, reports Robinson Meyer at The Atlantic. While an asteroid strike is survivable, comets move twice as fast—roughly 125,000 miles per hour, writes Mike Wall at Space.com. Comets can create an extinction-level event, but only strike Earth once in roughly 50 to 60 million years, Yuhas reports.

“The biggest problem, basically, is there’s not a hell of a lot we can do about it at the moment,” Nuth told the AGU audience, pointing out that it could take five years of work to build any sort of craft that could divert or destroy the comet, Yuhas reports. “Comets have largely been ignored by people that are interested in defending the planet.”

Wall writes that one reason comets have been off the radar, so to speak, is because researchers have not believed there was much we could do to protect the planet from the icy gas balls. But Nuth argues humans do have some options when it comes to comets, but we have to prepare now.

According to Nuth, NASA should build two spacecraft and stow them away in case a dangerous comet or asteroid is detected. That would help cut the response time from five years to roughly 12 months. One craft would be an observer, which could be launched to study the object and learn more about its trajectory, Wall reports. The second would be an interceptor, equipped with technology to redirect or destroy the object.

But these aren't the only solutions. Others proposals at the meeting include "cannonball technology" to physically deflect the rock through impact, explosion of a nuclear device nearby to knock it off its trajectory, or even a high-powered ground-based laser to warm the space rock, causing it to expel gasses and alter its trajectory.

Whatever the method, the message is clear—the threat from space is not just a Hollywood fantasy, and the sooner NASA and governments start working on practical solutions, the the better we will all fare when the "big one" finally comes hurdling toward our little blue marble.