The DART Mission

In a question of weeks, Nasa will be sending a spacecraft on course for an asteroid heading close to the earth to crash into it, on purpose. No, it’s not the script for the latest space adventure movie.

This is real. WORDS MICHEL CRUZ PHOTOGRAPHY NASA/JOHNS HOPKINS

NASA’S DART

LIKE A SPACE MOVIE, BUT FOR REAL

• SIZE: The Didymos asteroid is approximately 780 metres in diameter and the smaller Dimorphos is around 160 metres. • DISTANCE: DART’s impact will take place when the distance between Earth and the Didymos system is near its minimum, roughly 11 million kilometres. • TIMING: The impact is scheduled to occur between 26 September and 1 October 2022.

We know that asteroids have pummelled the earth for literally billions of years, helping to shape the planet and later destroying ecosystems, as in the famous case of the dinosaurs, but as none have threatened humanity in recorded history, we tend to think that was a one-off accident. The truth is that our planet is constantly being hit by objects from space, but since the majority of these range from space dust up to large boulders, they tend to burn up upon entry into the earth’s atmosphere and we don’t even notice. Residents in a remote part of Siberia did notice the crashing of a meteor that was somewhat bigger, back in 1908, as it completely demolished a forest (and everything else) within an area the size of a typical UK county.

Fortunately for all concerned, this is a sparsely populated area, and the impact which became known as the Tunguska Event caused very few deaths. Had it happened in a major metropolitan area such as New York or Tokyo, the death toll would have counted in the hundreds of thousands, for while the massive rock didn’t hit the earth in solid form but disintegrated several kilometres up in the air, the ‘meteor air burst’ created in this way is similar in force to a nuclear explosion. In fact, people were thrown to the floor several hundreds of kilometres away and the shock was felt all the way to Western Europe and Indonesia, then the Dutch East Indies.›

THE NEED TO PROTECT THE EARTH

To be fair, while such objects hitting the earth can produce the extinction of a whole species or ecosystem – including of course humans – this requires a huge lump of rock, which is very rare indeed. The Tunguska Event was the largest recorded impact of its kind in history, but this is not to say that it couldn’t happen again, or even that smaller and therefore relatively more frequent asteroids could not devastate part of the world. For this reason, NASA has been on a mission to reduce this potential danger, however distant it may be. The product of this endeavour is the development of Asteroid Deflection Technology, and DART – the Double Asteroid Redirection Test – the first product in a whole new field of space development.

The programme is part of Nasa’s new planetary defence mission, as directed by the specially focused Nasa Planetary Defence Co-ordination Office (PDCO), which works together with other departments of NASA, the US defence agencies and scientific research facilities to produce the hardware and software required for the mission. The main objective is to test the methodology in a real live environment, monitor its effectiveness and also assess the functioning of newlydeveloped technologies that have been specially created for the mission—and it’s all happening outside your window between 26th September and 1st October. So if you time it right, you might be able to look up and imagine a Star Wars like battle waging up there in the night sky. ›

DOUBLE ASTEROID REDIRECTION TEST

Dimorphos, the smaller asteroid that will be involved in the test, circles the larger Didymos, neither of which pose a direct threat to the earth as they are not on a collision course with our planet. The duo of asteroids is, however, going to pass by relatively close to us, and this makes it a convenient candidate for the testing of new plans to develop earth protection capabilities based upon the principle of Kinetic Impact Deflection – basically ramming a spacecraft (unmanned, of course) into an asteroid to knock it off course. It’s not the most elegant method, but while lasers and possibly even the manipulation of magnetic fields may become viable options in the future, a bowling alley style impact and redirection is the technology available to us right now.

From the light 650kg unmanned craft and the autonomous optical navigation system that directs it, to a new propulsion system with great potential for future deep space missions, not to mention new camera, sensoring and monitoring technologies, DART is a researcher’s dream come true, as it will escape the bounds of theoretical monitoring and provide a very rare opportunity for live testing and result measuring. Firstly, to see if an asteroid can be knocked off (collision) course this way, and secondly to get valuable development feedback on new technologies.

If you consider that an undetected asteroid entered the earth’s atmosphere as recently as 2013 and caused damage in six cities in the Chelyabinsk area of (again) Siberia, and that this object was only 18 metres wide, then you also need to know that space is literally littered with rocks both bigger and smaller.

NASA estimates that there are approximately 25,000 asteroids passing near us that are roughly the same size as Dimorphos and big enough to do some serious damage if they impacted. At 780m, Didymos is potentially even more dangerous, so DART will be launched from the Vandenberg Space Force Base in California with the use of a Space X Falcon 9 launch rocket, travelling at speeds of 24,000km/h on a mission to find and impact the asteroid Dimorphos some 11 million kilometres above us. Like all those science fiction movies come to life! e