Planetary Defense Test To See If An Asteroid’s Path Can Be Changed Is About To Launch

An upcoming test will explore the feasibility of using a “kinetic impactor” spacecraft to change the trajectory of an asteroid by crashing into it.

byJoseph Trevithick|
U.S. Homeland photo


NASA is about to try to use a "kinetic impactor" to alter the motion of an asteroid in space in a test that sounds like it was ripped straight from a Hollywood blockbuster disaster flick. The objective is to demonstrate the feasibility of using an interceptor of sorts to deflect future asteroids that might find themselves on collision courses with Earth.

The Double Asteroid Redirection Test (DART) spacecraft arrived at Vandenberg Space Force Base last month, NASA disclosed yesterday. It is now at SpaceX's Payload Processing Facility on that base, where work will start to load it on top of a Falcon 9 rocket next week. The actual launch is scheduled to take place from Vandenberg's Space Launch Complex 4 East (SLC-4E) on Nov. 23, 2021. The original plan had been to start this mission in July, but the launch date was pushed back due to unspecified technical issues and the ongoing COVID-19 pandemic.

Video thumbnail

DART's target is Dimorphos, which does not pose a threat to the Earth and is around 525 feet in diameter. The closest it has been recorded coming to our planet was within a distance of just over 4.46 million miles in 2003, per a database that NASA maintains, and is expected to be around 6.8 million miles away when the spacecraft collides with it. This asteroid, which was only formally given a name last year as part of this mission, orbits around another, larger one named Didymos with a diameter just shy of 2,560 feet.

The hope is that the DART spacecraft will demonstrate that is possible to alter the motion of an asteroid in a deliberate way by smashing another object into it in the vacuum of space. Even a small change in course initially as a result of the impact could be useful as the deviation could grow substantially over time, putting the threat outside of well outside of any potential impact window by the time it comes anywhere near Earth. The force also needs to be measured enough so as not to shatter the target, which could simply create multiple threatening objects.

"DART will be the first demonstration of the ‘kinetic impactor’ technique in which a spacecraft deliberately collides with a known asteroid at high speed to change the asteroid’s motion in space,” Lindley Johnson, NASA’s Planetary Defense Officer, said in a statement. “This technique is thought to be the most technologically mature approach for mitigating a potentially hazardous asteroid, and it will help planetary defense experts refine asteroid kinetic impactor computer models, giving insight into how we could deflect potentially dangerous near-Earth objects in the future.”

DART, which the Johns Hopkins Applied Physics Laboratory (APL) designed and built for NASA over a period of more than a decade, only has one instrument, the Didymos Reconnaissance and Asteroid Camera for Optical navigation, or DRACO. Combined with an antonymous navigation system, the spacecraft will use DRACO to identify Dimorphos and aim itself toward the asteroid. It does incorporate advanced technologies, including a xenon-powered NEXT-C ion propulsion system, which is intended to provide improved performance and fuel efficiency over previously propulsion options, and "a flat, slotted high-gain antenna for efficient communication between Earth and the spacecraft," according to NASA.

A graphic showing components of the DART spacecraft, including the DRACO instrument, the NEXT-C engine, the  Radial Line Slot Array (RLSA) antenna, and the ROSAs (Roll-Out Solar Arrays). The ROSAs are seen in their stowed position., NASA
The actual DART spacecraft., NASA/Johns Hopkins APL/Ed Whitman

"I’m both amazed and grateful that DART has gone from a twinkle in the eye to a spacecraft in final preparation for launch within 11 years," said Andy Cheng, the DART investigation team lead at APL and who is credited with coming up with the original idea for this spacecraft, said in a statement. “What made it possible was a great team that overcame all the challenges of building a spacecraft to do something never done before.”

A small CubeSat provided by the Italian Space Agency, called the Light Italian CubeSat for Imaging of Asteroids, or LICIACub, will accompany DART on this mission. LICIACub will initially be attached directly to DART, but will be released five days before the impact in order to gather imagery of the test. The European Space Agency (ESA) already has plans to launch an additional probe, called Hera, years from now in order to better assess what effect the impact actually had on Dimorphous.

Video thumbnail

DART is part of NASA's broader Planetary Defense efforts, which also include various terrestrial and space-based sensors, including optical and radar telescopes on the ground, to spot and track asteroids that could pose potential threats to Earth. NASA's Planetary Defense Coordination Office has supported various related research projects, such as sending the OSIRIS-REx probe to the asteroid Bennu to collect samples and other data, as well.

Of course, it remains to be seen whether the DART concept will show real promise as a result of this test. NASA is likely years away from getting its hands on a robust set of data from this mission. It will take a not-insignificant amount of time for the spacecraft just to get to Dimorphos in the first place. There is always the potential for issues to emerge during that transit, even before it attempts to actually collide with the asteroid.

At the same time, the risk of an asteroid, or another type of object from space, hitting Earth is very real. In 2013, a meteorite more than 66 feet in diameter exploded in the atmosphere above the Russian city of Chelyabinsk, sending out a massive shockwave that shattered windows. 

Video thumbnail

This was the largest known natural object to enter the Earth's atmosphere since the Tunguska event, which took place in Russia's Siberia region in 1908. That incident involved an exploding meteoroid estimated to have been between 160 and 200 feet in diameter, the blast from which flattened some 830 square miles of forest, destroying some 80 million trees in the process.

Asteroids and other objects continue to pass by the Earth on a regular basis, with the vast majority being harmless. Just in October, a very small asteroid around 6.6 feet in diameter, came relatively close to our planet, but did not enter the atmosphere. More are apparently headed our way soon.

However, while we arm ourselves for seemingly every conceivable terrestrial conflict, and now even a possible one in space, a truly devastating or even human-life ending event could be hurtling our way right now. History has shown this is only a matter of time.

So, after more than a decade preparing DART for this mission, NASA is no doubt eager to send out this spacecraft to finally find out whether this disaster movie-esque idea of redirecting an asteroid through kinetic means and pushing it away from Earth is at all feasible.

Contact the author: