Like it or not, there are asteroids hurtling all around planet Earth and through the solar system.
Massive chunks of space rock, with the potential to cause some serious damage.
And we know that across the history of Earth there have been major impact events, which have
served to change our planet forever. We also know, though, that the chances of an asteroid striking
today, tomorrow, or next week are extremely low. But still, NASA are apparently worried
enough to take matters into their own hands. This is Unveiled, and today we’re answering
the extraordinary question; why did NASA just launch a planetary defense mission?
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The Double Asteroid Redirection Test. Remember the name because it could yet become one of the most
significant space missions of recent times. Launched on November 24th, 2021, and often
abbreviated to DART, this is one of NASA’s most ambitious planetary defense projects to date.
Tweeting about DART shortly after launch, the SpaceX head, Elon Musk,
even claimed that it could one day avenge the dinosaurs - referencing the widely held view
that the dinosaurs were ultimately killed off by the devastating effects of an asteroid impact.
So, what is DART? And what does NASA hope to achieve with it? First and foremost, it’s what’s
known as a kinetic impactor spacecraft. It’s been designed with one main purpose; to crash into a
target, and hopefully to change the orbit of that target - to change the way it moves through space.
This, in simple terms, is currently held as one of our best strategies, were we ever to
discover an asteroid on a natural collision course with Earth. The idea is that, in that scenario,
we would send a DART-like vehicle to intercept the asteroid and avert disaster on the ground.
There are some other things of note with DART, though. And, while it will ultimately smash
itself into smithereens in the name of science and progress, it features some cutting edge
technology in the meantime. For one, there’s the Didymos Reconnaissance and Asteroid Camera for
Optical navigation (or, DRACO). This bit of kit is how DART will navigate to its target,
which is the double asteroid system known as Didymos. More specifically, though, if all goes to
plan then DART will hit the smaller part of this binary system, the minor-planet moon, Dimorphos.
We’ll take a closer look at the asteroid itself shortly but,
sticking with the tech that’s packed into DART, there’s also the NASA Evolutionary Xenon Thruster.
Otherwise known as the NEXT Ion Thruster, this is what will power DART through space,
using solar electricity to move the vehicle at up to 90,000 miles per hour. And, finally, there’s a
CubeSat, called LICIACube, that will be carried by DART for most of the journey… before it separates
around ten days before the scheduled impact. This CubeSat has been provided by the Italian
Space Agency, and it will observe the impact when it happens, beaming the images back to Earth.
That question of when is one with an apparently clear answer, though.
DART should crash into its target Dimorphos on or around 26th September, 2022,
meaning it’s journey through space should take around ten months. There are various predictions
as to the outcome of the impact, but in general it’s hoped and calculated that once DART strikes
the smaller rock of the two in the Didymos binary, it should force it to change course and speed.
At first, the changes will appear minimal, but over time they should become more significant.
There are a lot of unknowns here, however, and getting a firmer grip on these unknowns is one of
the primary reasons for the mission. At present, the team behind DART can predict what should
happen to Dimorphos in the short and long-term, but there’s no certainty. This is, after all,
a ground-breaking, never-before-tried experiment. It should be noted, as well, that while it’s
NASA’s name that’s all over most of this project (and it is NASA that’s leading and has had the
most influence) DART is really a joint effort - with the Johns Hopkins Applied Physics Laboratory
partnering up. It’s an international achievement, too. This unique payload was actually launched on
a SpaceX Falcon 9 rocket. There’s been mission involvement from various other space agencies,
as well, including the Italian Space Agency (with the LICIACube), JAXA in Japan, and ESA the
European Space Agency. Regarding ESA specifically, NASA had at one time been in a sort of two-way
race with Europe to get the world’s first asteroid redirection mission off the ground - as ESA had
been planning something similar. Now, though, thanks to various deals and agreements that
were made, one of ESA’s main roles is to stage a follow-up mission instead, known as Hera. It will
launch in 2024 and reach Didymos in 2027, for an in depth look at the long-term effects of DART.
But, as impressive as all this is, the question still remains as to why NASA and everyone else
has launched this mission now? Should we, the helpless onlookers of Earth, be concerned about
an imminent asteroid disaster? The short answer is still no. Both NASA and the Johns
Hopkins Applied Physics Lab have been at pains to assure us that the Didymos system does not pose
a real-life threat to Earth, and also that DART’s smashing into it will not redirect it towards us.
Rather, NASA has described Didymos as “a perfect testing ground”. And this links back up with Elon
Musk’s comment about avenging the dinosaurs. Ultimately, the DART mission is about
seeing what will happen. We know that if an asteroid were to strike Earth,
then it could spell ecological ruin - as it has done in the past. An Armageddon event the like of
which humankind might not survive. But, thanks to the last century or so of space tech development,
we’re now remarkably well equipped to check for asteroids and track them through the solar
system. Organisations like CNEOS (or, the Center for Near-Earth Object Studies) at NASA’s Jet
Propulsion Laboratory can’t claim to catch every single asteroid that passes our way, and there
are still some that take us by surprise… but, in general, more so than any generation before us,
we know about the space rocks that are soaring above our heads. And we know that, at present,
while there are some that will come closer than others, there’s no immediate danger.
This might’ve led to some criticism of DART as an unnecessary venture but,
in the long-term, it could well prove to be a vital first step in protecting our planet.
Picture the scene, generations from now, when our worst fears have been realised and a world-ending
asteroid is heading straight for us. Without innovative missions like DART in our history, we’d
be sitting ducks idly waiting for the apocalypse. But continue with missions like this one, and we
give ourselves a far better chance. Really, this is the kind of crazy space mission that sounds at
first like it belongs more to science fiction… but we’re now midway through the twenty-first
century and we’re making it happen in real life. That’s exciting, but it’s by no means the end.
And, in fact, kinetic impactors aren’t even our only option when it comes to asteroid avoidance.
Other possibilities include using nuclear weapons to redirect asteroids, or ultra-powerful lasers,
or what’s known as a gravity tractor. Gravity tractors involve perhaps the most similar strategy
to kinetic impactors, because again they make use of a purpose-built spacecraft for the job.
The major difference, however, is that while an impactor does strike the asteroid itself,
a tractor doesn’t. Instead, it spends a lot of time close to the asteroid,
and then over that time it exerts a gravitational influence… to change its direction that way. So,
watch this space for future ground-breaking missions focussing on these strategies, too.
For now, though, NASA and the rest of the world waits for September 2022,
when the DART mission is scheduled to reach its dramatic conclusion.
Thanks to a nearby CubeSat, we’ll have close-quarter visuals of the event,
as humankind watches on in the hope that this endeavour will prove a successful one. If it does
then we’ll have certainly upped our game in terms of fighting back against the threat of space.
The asteroids that once triggered massive extinction events might finally become less
of an existential danger. And that’s why NASA just launched a planetary defense mission.
What do you think? Is there anything we missed? Let us know in the comments, check out these other
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