Page 16 - The 'X' Chronicles Newspaper - Febrary/March 2020 Edition

16 What To Do If Killer Planet Is Aimed At Us

What should we do if a

'planet-killer' asteroid

takes aim at Earth?

By Rafi Letzter
Live Science

Researchers at MIT calculated which
option is best depending on the asteroid
and its path through space.

If a giant object looks like it's going to slam into
Earth, humanity has a few options: Hammer it
with a spacecraft hard enough to knock it off
course, blast it with nuclear weapons, tug on it
with a gravity tractor, or even slow it down
using concentrated sunlight.
We'll have to decide whether to visit it
with a scout mission first, or launch a full-scale
attack immediately.
Those are a lot of decisions to make
under existential duress, which is why a team of
MIT researchers have come up with a guide,
published February in the journal Acta after a nuclear explosion and because political the specific planet killer.
Astronautica, to help future asteroid deflectors. concerns about nuclear weapons could cause Applying those calculations to two well-
In movies, an incoming asteroid is problems for the mission. known planet-killer asteroids in Earth's general
usually a very last-minute shock: a big, deadly In the end, they landed on three options neighborhood, Apophis and Bennu, the
rock hurtling right toward Earth like a bullet out for missions that could reasonably be prepared researchers came up with a complex set of
of the darkness, with only weeks or days on short notice if a planet-killer asteroid were instructions for future asteroid deflectors in the
between its discovery and its projected impact. spotted heading toward a keyhole: event one of those objects started heading for a
That is a real threat, according to an April 2019 keyhole.
presentation by NASA's Office of Planetary • A "type 0" mission where a single, heavy Given enough time, they found, type 2
Defense that Live Science attended. But NASA spacecraft was fired at the incoming object, missions were almost always the right way to
believes that it's spotted most of the largest, aimed using the best available information deflect Bennu. If time was short, though, a
deadliest objects that have even a small chance about the object's makeup and trajectory to quick-and-dirty type 0 mission was the way to
of striking Earth — the so-called planet killers. knock it off course. go. There were just a handful of instances where
(Of course, there are probably plenty of smaller • A "type 1" mission where a scout is launched type 1 missions made sense.
rocks — still large enough to kill whole cities — first and collects close-up data about the Apophis was a different, more
that remain undiscovered.) asteroid before the main impactor is complicated story. If time was short, a type 1
Because most of the large objects in launched, in order to better aim the shot for mission was usually the best option: collect data
Earth's neighborhood are already being closely maximum effect. quickly in order to properly aim the impact.
watched, we'll likely have plenty of warning • A "type 2" mission where one small Given more time, type 2 missions were
before one strikes Earth. Astronomers watch impactoris launched at the same time as the sometimes better, depending how difficult it
these space rocks as they get near Earth to see scout to knock the object a bit off course. appeared to be to deflect from its course. There
whether they're likely to cross through one of Then all the information from the scout and were no situations where a type 0 mission made
their "keyholes." Every Earth-threatening the first impact are used to fine-tune a sense for Apophis.
asteroid gets closer and further from Earth at second small impact that finishes the job. In both cases, if the time got too short,
different points in its orbit around the sun. And the researchers found no mission would be
along that path, near Earth, it has keyholes. The problem with "type 0" missions, the successful at diverting the rock.
Those keyholes are regions of space that it has to researchers wrote, is that telescopes on Earth The differences between the rocks came
pass through in order to end up on a collision can only gather rough information about planet down to the level of uncertainty about their
course during its next approach to our planet. killers, which are still faraway, dim, relatively masses and velocities, as well as how their
"A keyhole is like a door — once it's small objects. Without precise information on internal materials would react to an impact.
open, the asteroid will impact Earth soon after, the object's mass, velocity, or physical makeup, hese same basic principles could be used
with high probability," Sung Wook Paek, lead the impactor mission will have to rely on some to study other potential planet killers, and future
author of the study and a Samsung engineer who imprecise estimates, and has a higher risk of studies could incorporate other options for
was an MIT graduate student when the paper failing to properly knock the incoming object deflecting the asteroids, including nuclear
was written, said in a statement. out of its keyhole. weapons, the researchers wrote. The more
The easiest time to stop an object from Type 1 missions are more likely to complex the list of options, the more difficult the
hitting Earth is before it hits one of those succeed, the researchers wrote, because they can calculation gets. Eventually, they wrote, it
keyholes, according to the paper. That will keep determine the incoming rock's mass and velocity would be useful to train machine learning
the object from getting on the route toward an far more precisely. But they also take more time algorithms to make decisions based on the exact
impact in the first place — at which point saving and resources. Type 2 missions are even better, available data in any planet-killer scenario. []
Earth would require far more resources and but take yet more time and resources to get
energy, and involve much more risk. underway. THE ‘X’ ZONE TV CHANNEL
Paek and his co-authors tossed out most The researchers developed a method for Welcomes Dr. Bernard Beitman, MD
of the more exotic asteroid-deflection schemes calculating which mission is best based on two and his Coincidence Vignettes starting
out of hand, leaving only nuclear detonation and factors: the time between the mission start and May 2020. You can listen to Dr. Beitman
impactors as serious options. Nuclear detonation the date the planet killer will reach its keyhole, on the ‘X’ Zone Broadcast Network,
is problematic as well, they wrote, because it's and the difficulty involved in properly diverting www.xzbn.net.
uncertain exactly how an asteroid will behave