OPENSPACE 24: The Future of Space Exploration | Page 33

16344 asteroids and
106 comets have been
discovered, from which
639 could pose a risk
to Earth.
Credit: ESA.
and anything above a few kilometers will have global advance warning available before the expected impact. It is
consequences, which can be as dramatic as what happened essential to discover NEOs as early as possible and collect
66 million years ago when the dinosaurs became extinct after enough observation data to identify well in advance those
a 10-kilometer asteroid hit the Earth. that can result in a threat. So far, there has never been a
Fortunately, astronomers have discovered the vast majority
case of an object large enough that a deflection was needed.
of these large km-sized asteroids, and we are confident none
the next century. However, the number of smaller objects Once you find a threat, how do you evaluate the
probability of a collision?
of a few hundred meters in diameter is still unknown, and Whenever a new dangerous asteroid is discovered,
new ones are being discovered every day. Those are the one of the main tasks of our Centre is to make sure that
most important ones to spot as quickly as possible, because enough observations are collected to clarify the risk. New
today’s technology would be sufficient to deflect or destroy observations will hopefully allow us to determine that the
them if they turned out to be on a collision course. object is not as dangerous as thought or, if it turns out to
of them are on a collision course with our planet at least for
really be on a collision course, they will guarantee enough
How can we divert or even destroy incoming NEOs?
advance warning to organize a possible mitigation effort.
The possibility of diverting or destroying an incoming asteroid Once a credible threat is discovered, the decision on how
exists, and many methods have been studied in detail. They to proceed will be made at an international level. Recently
range from simply hitting it with a heavy projectile launched the International Asteroid Warning Network (IAWN) and
from Earth to a milder alternative—such as dragging the Space Mission Planning Advisory Group (SMPAG) have been
asteroid away over time—to the extreme case of detonating established at the United Nations level, and they will be the
nuclear devices in its proximity to alter the trajectory. The internationally recognized entities in charge of coordinating
effectiveness of all these techniques depends heavily on the the global response to a possible future asteroid impact.
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