BALTIMORE — A team of scientists, astronomers and engineers meets weekly in a conference room on a Howard County, Md., research campus and plans to save the world.

“Keep calm and carry DART,” reads a poster on the wall.

DART — the Double Asteroid Redirection Test — is their plan to avert catastrophe. It’s also NASA’s first mission not to explore space, but to defend against it.

The research team at the Johns Hopkins University Applied Physics Laboratory in Laurel plans to launch a spacecraft, speed it up to 15,000 mph and smash it into an asteroid.

The impact, they hope, will bump the big space rock off course — actually more like nudge it slightly. Someday, the thinking goes, this method may save humans from the fate of the dinosaurs.

“Kind of like a big missile,” said Elena Adams, the mission’s lead engineer. “It’s very exciting. You are actually doing something for the fate of humanity.”

An estimated 100 tons of space debris falls to Earth every day, according to scientists with the NASA’s Jet Propulsion Laboratory at the California Institute of Technology. This debris is mostly dust and sand.

Occasionally, space sends something bigger.

In February 2013, a fiery meteor cut across the Siberian sky. It came streaking down as fast as 40,000 mph. Then came a midair explosion, a flash and boom.

The shock wave blew out windows across the Russian city of Chelyabinsk. More than 1,000 people were hurt, mostly from shattered glass. Scientists estimate the meteor unleashed a force stronger than the atomic bomb detonated in Hiroshima.

The rock was about the size of a school bus. That’s a pebble compared to a meteor believed to have exploded over remote Siberia in 1908, flattening hundreds of square miles of forests. Researchers estimate that fireball equaled 185 Hiroshima bombs and heated the air to near 50,000 degrees.

Sometime in a span of several hundred-thousand years, scientists say, an asteroid even larger could strike Earth and wreak global disaster. They believe a meteor 8 to 10 kilometers in diameter crashed into the Gulf of Mexico 65 million years ago and killed off the dinosaurs.

“We’ve found all the nearest asteroids that size. We’re safe from that,” said Paul Chodas, who runs an asteroid search team at the NASA lab in California.

But smaller asteroids can unleash megatons of energy too.

“Even down to the 1-kilometer size, if it hits in the right spot, could cause global devastation,” Chodas said. “It’s the small asteroids that pose the risk.”

In the 1990s, Congress ordered NASA to locate dangerous asteroids in the solar system. Researchers today aim to catalog the orbits of 90 percent of asteroids 460 feet or bigger.

They predict 25,000 of them hurtle through the solar system. Chodas said they have found and charted about a third of them.

Scientists have long debated what to do if they discover one on a collision course with Earth.

NASA has considered nuking an asteroid with warheads, but that risks turning a single incoming rock into a shower of debris as happened in the Hollywood film “Deep Impact.” Another plan calls for flying a spacecraft beside the asteroid and gradually drawing it off course like a gravity tractor.

DART offers a third strategy, and will be the first given a live test.

About the size of a Honda Civic, the solar panel-powered DART is scheduled for launch in summer 2021, and its journey will take over a year.

Its target is the tiny moon of an asteroid.

“This is by far the smallest object anyone has ever flown a spacecraft into,” said Andy Cheng, the mission’s co-lead and chief scientist in APL’s space department.

They plan for DART to reach speeds as fast as 15,000 miles per hour. The crash in October 2022 will fling debris from the asteroid moon. A small satellite will accompany the DART spacecraft to measure the effect.

“We don’t see the moon of the asteroid until we’re just an hour away,” said Adams, the engineer. “That last hour is going to be really thrilling.”