Asteroid deflection: Understanding NASA's DART Mission

Here's everything you need to know about NASA's mission to deflect asteroids.

Asteroid illustrative (photo credit: Wikimedia Commons)
Asteroid illustrative
(photo credit: Wikimedia Commons)

NASA is set to launch its long-awaited mission to test whether it is possible to deflect an asteroid that may be on a collision course with Earth. 

Called the Double Asteroid Redirection Test (DART) Mission, the mission has been in the works for a while, and is the result of collaboration between NASA and Johns Hopkins University's Applied Physics Laboratory (APL).

But what does the DART Mission entail? When will it launch and how long will it take?

Here is everything you need to know about the DART Mission.

What is DART?

The DART Mission seeks to launch a specially designed rocket to alter the path of an asteroid, effectively punching an asteroid with a rocket with enough speed to change its direction by a fraction of a percent. NASA has likened this to a "pillow fight in microgravity."

The technology involved includes the "kinetic impactor" technique, which should be able to change an asteroid's motion in space.

A spacecraft will crash straight into an asteroid at a speed of around 6.6 kilometers per second, which should force it to change the speed of its orbit.

Even if only by a fraction of a percent, it would be enough to be observed and measured by astronomers.

DART will be the first attempted demonstration of the kinetic impactor technique.

An artist's rendering of cosmic collisions surrounding a star similar to the sun.  (credit: REUTERS/Gemini Observatory/Jon Lomberg/Handout MR/CP)An artist's rendering of cosmic collisions surrounding a star similar to the sun. (credit: REUTERS/Gemini Observatory/Jon Lomberg/Handout MR/CP)

Which asteroid is the target of the mission?

DART is set to fly for the Didymos binary asteroid system that consists of two asteroids, 65803 Didymos, which is around 780 meters in diameter (twice the size of the Empire State Building), and Dimorphos, which is around 170 meters in diameter (around the size of the Washington Monument). Dimorphos will be the specific target.

There is no risk of Didymos or Dimorphos striking Earth any time soon and their orbit around the sun does not cross Earth's orbit. As such, they are the ideal target for a test. 

What is the DART spacecraft?

The DART spacecraft is relatively simple and low-cost. It is essentially a box that is 1.2 x 1.3 x 1.3 meters, with other structures extending it. In total, it is 1.8 meters in width, 1.9 meters in length and 2.6 meters in height. Its solar arrays will stretch it further, each measures 8.5 meters.

The craft has a mass of around 610 kilograms, but on impact will have a mass of 550 kilograms. It carries around 50 kilograms of propellant for maneuvers and attitude control and 60 kilograms for propulsion, though it will use just 10 kilograms of the latter.

It has only a single instrument known as the Didymos Reconnaissance and Asteroid Camera for Op-nav (DRACO), which is designed to help the craft navigate and provide visuals. However, it also comes equipped with Roll-Out Solar Arrays (ROSA), which will be used to power the NASA Evolutionary Xenon Thruster - Commercial (NEXT-C) solar-powered electric propulsion system. 

It will be launched by a SpaceX Falcon 9 rocket, from where it will eventually be separated.

Why do we need the DART Mission?

Ateroids can be dangerous and an asteroid impact is one of the greatest possible natural disasters that could occur. The danger of even small ones is something well-known to experts, with space agencies around the world monitoring for potential catastrophic impacts, as well as researching potential means of stopping them.

 An asteroid is seen crashing into the Earth in this artistic rendering of an asteroid impact. (credit: PIXABAY) An asteroid is seen crashing into the Earth in this artistic rendering of an asteroid impact. (credit: PIXABAY)

NASA keeps track of all Near-Earth Objects (NEOs) that are detected, with special attention given to those deemed Potentially Hazardous Asteroids (PHAs), all of which have a diameter of at least 140 meters. These are the ones that could cause catastrophic damage to the planet upon impact.

But even the smaller ones can be dangerous.

The last known significant asteroid impact was on February 15, 2013, when an asteroid exploded in the air above Chelyabinsk, Russia. This asteroid was just 17 meters wide, and while it didn't cause any fatalities, the shock wave from the explosion shattered windows in six different Russian cities and 1,500 people to need medical attention.

Larger ones pass by the planet frequently– some have even come relatively close. 

NASA has declared the Earth free of risk of any asteroid impact for the next century. However, the danger is still present and building a defense against a catastrophic asteroid impact is something worth investing in.

Does DART have any flaws?

A big issue with DART is how long it has taken for the mission to get off the ground. As such, it could mean a tighter time frame when dealing with an impending disaster. 

Are there other options apart from DART?

Technically, yes. 

Another deflection model was proposed in July 2021 by European aerospace giant Airbus. Essentially, its method would be a more ad-hoc means of deflecting asteroids. 

It relies on repurposing communications satellites in orbit around the planet, essentially hijacking them and using them to deflect incoming asteroids, should there be a need to do so.

The science behind this method seems sound – although it also has its flaws, such as being able to deflect the asteroid when it's far enough away from the planet, which could hypothetically be over six months away.

Other methods focus on disruption: meaning destroying the asteroid, especially with a nuclear weapon. This is the type of method most commonly seen in pop culture and is a staple of science fiction movies. However, it has many issues and is one of the main things the DART Mission is trying to avoid. 

It was often feared that using nuclear weapons would result in fragments from the asteroid raining down on Earth and causing severe damage anyway, though some recent studies have shown this may be a better alternative than previously thought. However, it would also still take time.

 Asteroid impact: How can we stop one from happening? (credit: PIXABAY) Asteroid impact: How can we stop one from happening? (credit: PIXABAY)

Another method proposed uses kinetic penetrators to blow up the core of the asteroid, which could be done at much shorter notice. 

The fragments would then be spread out into a cloud of fragments and, if not blown completely off course, would then head into the Earth's atmosphere at around 60 times the speed of sound. 

But this is where the Earth's atmosphere kicks in, as entering the atmosphere at such a high speed causes it to experience severe levels of heat and pressure. These stresses would in turn cause the fragments to explode further, creating sonic booms.

This may seem terrifying to some, because, as noted by the scientists involved in the study, it would seem similar to the explosion of a thermonuclear bomb. But it would only be a large and harmless "light and sound" show, so there is no nuclear radiation risk. Dust could still be present, but it would not be so catastrophic as to cause a worldwide climate disaster scenario.

When does the DART Mission launch?

DART is currently set for launch on 1:20 a.m. EST on November 24.

Stay tuned to find out more!