NASA will smash a spacecraft into an asteroid in a planetary defense test

NASA will be testing techniques to redirect an asteroid on Monday as a part of a larger planetary defense strategy.

The Double Asteroid Redirection Test (DART) mission is targeting a binary asteroid system Didymos.

The system includes two asteroids, the larger Didymos, which is about a half mile across, and smaller Dimorphos, which is about 525 feet across. Mission planners describe the system as an ideal testbed for the first planetary defense experiment.

At 7:14 p.m., DART will smash into Dimorphos.

The asteroid will first appear as a single point of light that grows larger as DART approaches at about 14,000 miles per hour, revealing more and more of it in detail. Then the feed will go black.

We'll be watching all this happen via Didymos Reconnaissance and Asteroid Camera for Optical navigation (DRACO), a high-resolution imager which also provides navigation to ensure DART hits its target.

DRACO is derived from the Long Range Reconnaissance Imager (LORRI) that helped the New Horizons mission deliver breathtaking images of Pluto.

LICIACube (Light Italian CubeSat for Imaging of Asteroids) was also deployed from DART about two weeks ago to watch the impact from a distance. LICIACube will study the formation of the plume generated by the impact and how it changes in the moments following impact.

Scientists hope this will reveal much about the structure of the asteroid surface material.

This may sound like a plot of a sci-fi movie, but is a very real demonstration of kinetic impacter technology to adjust the speed and path of an asteroid that might pose a very real threat to Earth.

Huge space rocks hurtling for Earth have been a popular plot point in science fiction films for decades.

But DART won't be trying to destroy Dimorphos. It can't. The small-car-sized spacecraft weighs only about 1,260 lbs and is nearly out of fuel.

Dimorphos is 50 stories of rock.

The idea here is to slow the moonlete just a little, changing its path around Didymos.

Over the coming months, a network of ground and space based telescopes will monitor Didymos, looking for changes in brightness.

As smaller Dimorphos passes in front of and and behind Didymos in this eclipsing binary system, the brightness changes. This tells astronomers a lot about the orbit.

Small asteroids are observed passing between earth and the moon’s orbit several times a month. Meteoroids – very small fragments of asteroids and comets less than 3 feet in size – hit earth’s atmosphere and explode nearly every day, causing the fireball events that are seen by people.

While no known asteroid poses a significant risk of impact with Earth over the next 100 years (the highest risk of impact for a known asteroid is a 1 in 714 chance of impact by an asteroid designated 2009 FD in 2185), near Earth objects continue to be discovered.