We're Planning to Shoot an Asteroid to See What Happens

What better way to understand how to deflect an incoming asteroid than to smash into one to see what happens?

What better way to understand how to deflect an incoming asteroid than to smash into one to see what happens?

This may sound like the storyline to a certain science fiction movie involving a team of oil drillers, but this is science fact, and Europe has started planning a mission to map a small target asteroid that NASA will attempt to shoot with a speeding spacecraft, no nukes required.

Yes, this will be the mother of all asteroid missions that will see the collaboration of international space agencies unite to tackle an ever-present global threat.

GALLERY: Top 10 Ways to Stop an Asteroid

As the first half of the joint Asteroid Impact & Deflection Assessment mission, the European Space Agency this month has started planning for the launch of its Asteroid Impact Mission (AIM) in October 2020.

AIM's target will be the binary asteroid system of Didymos, which is composed of a main 800 meter-wide hunk of space rock circled by a smaller 170 meter-wide asteroid informally known as "Didymoon." It's the smaller asteroid that the joint NASA/ESA mission is interested in bullying.

Once AIM arrives at Didymoon, it will carry out an impressive array of mapping and surveying tasks, utilizing small cubesats that will be launched from the main satellites to gather data from the asteroid's vicinity. ESA also hopes to land a small lander on Didymoon to complete the work. AIM will utilize a high-bandwidth laser communications system, the Optical Ground Station, based on Tenerife in the Spanish Canary Islands (located off the coast of Morocco) to relay data throughout, producing high-resolution optical and thermal maps.

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AIM will be a science mission on steroids, a prelude to NASA's dramatic followup mission, the Double Asteroid Redirection Test or DART. You do, after all, have to take AIM before you throw the DART. (Best use of space acronyms ever.)

With a planned Didymos arrival time of 2022, DART will be accelerated to 6 kilometers per second - that's nearly 14,000 milers per hour - and it will punch into the smaller Didymoon... and the world will watch to see what happens next.

"AIM will be watching closely as DART hits Didymoon," said ESA's Ian Carnelli, AIM mission manager. "In the aftermath, it will perform detailed before-and-after comparisons on the structure of the body itself, as well as its orbit, to characterize DART's kinetic impact and its consequences.

"The results will allow laboratory impact models to be calibrated on a large-scale basis, to fully understand how an asteroid would react to this kind of energy. This will shed light on the role the ejecta plume will play – a fundamental part in the energy transfer and under scientific debate for over two decades."

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This will be the first time in human history that we've taken a vehicle, deliberately smashed it into a celestial body with the only intention of seeing how it reacts. The measurable results of the impact will be used to better prepare humanity should we be faced with the very real possibility of being hit by an asteroid that could cause regional, or even global, damage.

Understanding how an asteroid reacts to being hit is critical if we are to work out what we can possibly do to deflect hazardous space rocks in the future. Will they break apart on impact? Are they solid? Will the impactor just embed itself in a malleable rubble pile? Do we in fact need that nuclear warhead? In short, we're not entirely sure.

In 2005, NASA's Deep Impact mission collided a dense copper impactor into the nucleus of comet Tempel 1. However, this attempt wasn't to deflect the comet, it was to study the impact ejecta; the kinetic energy imparted on the comet was negligible.

Didymoon, however, is several tens of times smaller than Tempel 1, so the DART impact will have a small, yet highly significant effect on the asteroid's trajectory.

The Didymos binary will come within 11 million kilometers (nearly 30 times the Earth-moon distance) of Earth in 2022 (the point of closest approach with our planet), so it will be well out of harm's way as the DART impact takes place.

ANALYSIS: Don't Be Subtle, Nuke That Asteroid

Interestingly, Didymoon is nearly three times larger than the estimated size of the Tunguska impactor that leveled 80 million trees over a 2,150 square kilometer (830 square mile) region of Siberia in 1908. If an asteroid the size of Didymoon hit Earth, it would be classed as a "city killer", ripping out a crater 2.5 kilometers wide, causing wide-spread devastation. As a modern comparison, the meteor that exploded over Chelyabinsk, Russia, in 2013 was a mere 20 meters wide - nearly 9 times smaller than Didymoon.

The joint ESA/NASA mission will be discussed this month at the International Academy of Astronautics Planetary Defense Conference, at ESA's ESRIN Earth observation center in Frascati, Italy.

It's good to know, with all the asteroids that are out there - some with orbits that, in the future, could give Earth a very bad day - we have begun planning for an audacious mission to take a shot at an asteroid before an asteroid takes a shot at us.

Source: ESA via Phys.org