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Of all the risks that face our planet, the possibility of an
asteroid colliding with the Earth and sending humanity the way of the
dinosaur may be the most cataclysmic and least preventable. Sure, we may
have the cast of the movie Armageddon, but if a large space rock chooses
to head our way there really isn't much we can do about it,
regardless of Bruce Willis' formidable skill set.
So it's a good thing that NASA recently discovered that the
risk may not be as great as we thought. According to data from the
agency's Widefield Infrared Survey Explorer (WISE) telescope, there
are "only" about 20,500 mid- to large-size asteroids within a
120 million mile orbit of the Earth (a distance astronomers call
"near-Earth"). This is down more than 40% from previous
estimates of 36,000, which had been based on the findings of
less-accurate visible light telescopes. NASA scientists have also
located all but 70 of the 981 largest near-Earth asteroids, which, at
3,300-feet wide and larger, are the ones most likely to destroy the
planet in a collision. Thankfully none of these are expected to pose a
threat for centuries, which should give scientists plenty of time to
consider what one would assume is the next logical step--figuring out
how to stop them.
However, at a recent California Institute of Technology workshop, a
group of scientists and engineers had a much crazier idea. Rather than
focusing their efforts on preventing an asteroid strike, they spent four
days discussing ways to pluck one from space and bring it back to
Earth's orbit. The thinking is that an asteroid could provide a
valuable, and less expensive, jump-off point for future space
exploration since breaking out of an asteroid's weaker
gravitational field would take less fuel and power. Scientists and
engineers could also set up research bases and even mining operations,
which could be extremely lucrative considering some of these space rocks
are basically just mile-wide chunks of metals in concentrations that
have been estimated to be worth trillions of dollars.
Of course, if something goes wrong with our space-lasso project and
we tug a little too hard, we get squashed. It doesn't seem like
there is very much room for error. Besides, our recent track record of
keeping things in orbit has been a little suspect. In September, after
widespread media attention that there was a 1-in3,200 chance that it
could cause injury or damage, NASA's six-ton Upper Atmosphere
Research Satellite (UARS) crashed to Earth in the Pacific Ocean. This
was the largest uncontrolled satellite re-entry since the 75-ton Skylab
crashed to Earth in 1979. And as of this writing, a 5,000-pound German
X-ray telescope was expected to hit the planet around the first of
November. Researchers gave this satellite a 1-in-2,000 chance of causing
injury. Obviously we have plenty of falling space junk to worry about
already.
On top of this, researchers are speculating that with the thousands
of tons of space debris already orbiting the Earth and the cyclical
increase in solar activity during the next few years, we could start
seeing a higher rate of dangerous satellite re-entries. Increased solar
activity causes the upper atmosphere to expand and creates drag on lower
orbiting satellites and other objects, which pulls them down quicker.
This was why the UARS fell faster than scientists initially expected.
Now, many of those objects will burn up in the atmosphere-it was
expected that only 1,100 pounds of UARS material would survive its
re-entry--but that's plenty if any of those fragments land on your
house. Or worse, your head.
Despite the fact that grabbing asteroids out of space sounds like a
mad scientist's scheme in a bad movie and comes with, well,
planet-sized risks, I like the idea. Anything that increases the chances
that I'll get to live out the Star Wars dreams of my youth in some
distant solar system will always get my approval. I just hope they come
up with a good backup plan because it's not like insurance is going
to be able to cover it.
Hmm ... what about a giant net ... or airbags ... or a force field
...
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