Think of it as a crash course in averting asteroid crashes.

As part of the 2019 Planetary Defense Conference, NASA, the Federal Emergency Management Agency and their international partners will conduct a so-called tabletop exercise designed to show how they would react to the discovery of a fictional asteroid heading our way.

The exercise is being conducted as part of a federal "action plan" for defending Earth against asteroids that was announced last June. It will play out over the five days of the conference, which begins in College Park, Maryland, on Monday and runs through May 3. You can watch it live in the player below.

"Exercises like this have been run at several conferences over the years, and government agencies have also ​had them," Andrew Rivkin, a planetary astronomer at Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, and an expert on asteroids, told NBC News MACH in an email. "It's definitely worth doing, if only so people are aware of the issues and how complex some of them are."

Rivkin, who said he was participating in the exercise, likened it to a fire drill but added that the consequences of a major asteroid strike "could be very bad (just ask the dinosaurs)," referring to the impact of a six-mile-wide asteroid that is believed to have caused the dinosaurs' demise some 65 million years ago.

According to the loosely scripted scenario, astronomers discover that a make-believe space rock dubbed 2019 PDC has a one-in-100 chance of smashing into Earth in 2027. Participants in the exercise, including the European Space Agency and the International Asteroid Warning Network, as well as NASA and FEMA, will consider how they might mount space missions to investigate and possibly deflect the asteroid — and how the effects of an impact might be mitigated.

Even though 2019 PDC is fictitious, the threat posed by asteroid strikes is all too real. As of the start of 2019, more than 19,000 near-Earth objects (NEOs) had been discovered — and 30 more are discovered each week as astronomers continue to search for them.

"We've only found about one-third of NEOs large enough to cause severe regional damage, so we have a lot of work left to do," Amy Mainzer, an astronomer and asteroid expert at NASA's Jet Propulsion Laboratory in Pasadena, California, said in an email. "We need to build and operate more capable space- and ground-based telescopes, in my opinion," she added.

The animation depicts a mapping of the positions of known near-Earth objects (NEOs) at points in time over the past 20 years. There are more than 18,000 known NEOs, with new ones being discovered at the rate of about 40 per week. NASA/JPL-Caltech

So far, experts haven't identified any large objects on a collision course with Earth.

"We are confident that searches have found anything big enough to be a worldwide problem," Rivkin said in the email. "The space agencies of the world are working together to complete the search programs to make sure the neighborhood is safe, and NASA is planning a mission called DART [for Double Asteroid Redirection Test] to practice deflecting an asteroid just in case we ever need to do so. We don't anticipate having to do so any time in the foreseeable future, but it's good to be prepared!"

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