NASA’s Iron Dome: DART takes off to test asteroid deflection
The first-of-its-kind mission will head to the asteroid Dimorphos in the Didymos system and test kinetic impactors to see if an asteroid’s trajectory can be altered.
NASA's DART Mission spacecraft is seen launching on a SpaceX Falcon 9 rocket in its mission to crash into an asteroid. (photo credit: NASA HQ PHOTO/FLICKR)
NASA's DART Mission heads for an asteroid, from behind the NEXT–C ion engine (illustrative).
(photo credit: NASA/Johns Hopkins APL)
In a little under one year, this 550-kilogram spacecraft will
collide with Dimorphos at a speed of around 6.6 kilometers per second,
and will hopefully slightly alter the asteroid’s trajectory ever so
slightly using the never-before-tested “kinetic impactor” technique.
In
layman's terms, it means punching an asteroid with a rocket with enough
speed to change its direction by a fraction of a percent - a process
NASA has likened to a “pillow fight in microgravity.”
Watch NASA’s DART Mission Launch (Double Asteroid Redirection Test) Official Broadcast/Stream
According to the Davidson Institute of Science Education,
the educational arm of the Weizmann Institute of Science, DART is
designed to work similarly to the way missile defense systems such as
Israel’s Iron Dome function: intercepting a hostile target, only instead
of stopping it in its tracks, it deflects it away from Earth.
Even if only by a fraction of a percent, the change would be enough
to be observed and measured by astronomers, especially since Dimorphos
is set to be just 11 million kilometers away from Earth at the estimated
time of impact.
One
of the few observing the Didymos system both before and during the
scheduled impact is Dr. David Polishook, an astronomer from Israel’s
Weizmann Institute and a member of the DART investigation team. This is
because the asteroid's position means the collision will happen during
the night for Israel, making it more visible, compared to many other
observatories.
Others will have to rely on special cameras on board DART that will record the impact and send images of it back to Earth.
But why is this so important?
An asteroid impact is one of the worst 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.
Asteroid (illustrative) (credit: SHUTTERSTOCK)
The
last known significant asteroid impact was on February 15, 2013, when
an asteroid exploded in the air above Chelyabinsk, Russia. While it
didn't cause any fatalities, the shock wave from the explosion shattered
windows in six different Russian cities and caused 1,500 people to need
medical attention.
That
asteroid was just 17 meters in diameter But many others, like Dimorphos
or its 780 meter-sized neighbor Didymos, are much larger, and any
asteroid with a diameter of at least 140 meters could be catastrophic if
it impacted the planet. According to research from the Davidson
Institute, the impact of an asteroid the size of Dimorphos while hitting
the ground will release an amount of energy at least one thousand times
greater than the energy released by the first atomic bomb. Something
even larger, over 300 meters like the asteroid Apophis, could destroy an
entire continent.
And an asteroid over a kilometer in size could trigger worldwide cataclysms.
An asteroid is seen crashing into the Earth in this artistic rendering of an asteroid impact. (credit: PIXABAY)
Currently, humanity has no means of defense against asteroids. That is why missions like DART are so important.
Other
methods of planetary defense have been proposed as well, however. This
includes other means of deflection or even disruption, which means
destroying the asteroid, such as with explosives. But these are less
ideal methods.
“There
are multiple ways to deflect an asteroid from its orbit such as kinetic
impact, light and gravity,” Polishook explained. “So far, kinetic
impact is the most straightforward. Future experiments will probably try
other methods.”
Polishook also explained why deflection is a better alternative than disruption.
“Deflecting
asteroids admittedly requires more time compared to destroying it, but I
think that it's hard to realize how hard it is to blow up a rock 100
meters or more in size into dust,” he explained. “It is more plausible
the asteroid will break up into multiple components, some of them large
enough to be dangerous in their own right. It should be our last
solution.”
By NASA’s current predictions, the Earth is at no risk
of an asteroid impact within the century.
However, this only refers to
asteroids coming from the “front,” meaning heading towards the Sun. It
does not refer to asteroids coming from the “back,” meaning from the
direction of the Sun towards Earth.
Currently, NASA has no means of accurately predicting these asteroids, which often only get discovered after the fact.
This means that an asteroid could strike the Earth with little to no warning - something that has already happened.
“The
asteroid that impacted Chelyabinsk in 2013 arrived from the direction
of the Sun during daylight, thus it was impossible to observe it in the
weeks before impact,” Polishook said.
“However,
with enough time, meaning some years, we will eventually be able to see
all near-Earth asteroids at different angles. So, a major part of an
effective planetary defense program should include astronomic surveys to
endlessly look for unknown asteroids and measure their orbits.”
To
match with these threats, though, DART will need to catch up.
Especially since this test is just a scaled-down version of the real
thing.
“In six
months, an asteroid will only move around 11 kilometers away from its
current course after being deflected by the DART craft - not enough to
escape the Earth, which has a diameter of 13,000 kilometers,” Polishook
explained.
“In
the event of a real imminent asteroid impact, DART will have to be
larger and much faster in order to change the orbit of an asteroid in a
short enough time.”
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