
How to Defend Earth Against an Asteroid Strike - peter123
http://blog.wired.com/wiredscience/2009/03/planetdefense.html
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MikeCapone
I hope this isn't considered improper, but I wrote a few things on this topic
and I think I go a bit more in depth than this Wired piece. Here they are:

[http://michaelgr.com/2007/04/14/near-earth-objects-are-we-
wh...](http://michaelgr.com/2007/04/14/near-earth-objects-are-we-whistling-in-
the-dark/)

[http://michaelgr.com/2007/10/28/deflecting-earth-bound-
aster...](http://michaelgr.com/2007/10/28/deflecting-earth-bound-asteroids/)

[http://michaelgr.com/2008/01/27/near-earth-objects-we-
cant-b...](http://michaelgr.com/2008/01/27/near-earth-objects-we-cant-beat-
the-odds-forever/)

<http://michaelgr.com/2008/01/31/target-earth/>

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endtime
_"NASA's goal is to find 90 percent of those that are one kilometer across and
larger. We're at 82 percent right now, and we've only been aggressively
searching at current levels for eight to 10 years. Those ones just haven't
flown into view."_

Can anyone work out/explain how they know they're detecting 82% of them?

~~~
jrockway
They've detected all of them, but they are only going to talk about 82% of
them until they get more money. "Freemium research", I'll call it...

~~~
ramchip
...I don't know, but a more serious idea would be that the mass of everything
they found so far is 82% of the mass they'd expect to find according to
simulations. Like all those planets they discovered because their mass had an
influence on nearby bodies.

Not saying this is the actual reason, just that there are reasonable ways to
get a number like this...

~~~
endtime
Yeah, I was wondering about something like that too, but as they are putting
constraints on the single bodies of mass I'm not sure that's sufficient.

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thwarted
The best and most obvious defense against an asteroid strike would be not put
all our eggs in one basket and diversify our planetary holdings. Colonizing
other worlds seem to provide the most bang for the buck in terms of protecting
both what we have and what we will achieve from catastrophic failure of the
earth.

~~~
narag
That's a good long-term measure. But we also need something more cheap and
quick to set up right now.

~~~
thwarted
Would it really be much less expensive and take less time to build asteroid
defense systems (I almost typed "missile defense systems") which require us to
deal with space than just to start getting better at getting into space
anyway? Especially since most, if not all, of the technologies listed in the
article would be put to better use for transportation (of either humans or
goods) rather than as destructive ends (but such is the folly of human nature,
I suppose).

Planning for an asteroid strike strikes me as fear mongering, especially
without being able to do anything "unless people see the asteroid in time to
plan for it". Being resigned to a fate of having to continuously defend
doesn't sound good either. I'd rather consider the possibilities for mankind's
future as provided by getting off this rock than wallow in the status quo that
merely deflecting an asteroid would provide.

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gojomo
They don't mention my favorite idea: move the Earth. (I first saw a tiny blurb
about this idea in a magazine, then saw it mentioned as an idea Russian
scientists had considered.)

Apparently if you detonate a nuke on the moon, it will eject some of the
moon's mass. The resulting change to the Earth-moon system alters the Earth's
orbit around the sun ever-so-slightly.

However, 'ever-so-slightly' totaled over months or years means the Earth is
thousands of miles from where it would have been otherwise, converting a
direct-hit into a near-miss (or vice-versa!).

With enough warning, this could be a preferable approach, because it's
assembled from things we already know how to do (like reach the moon), rather
than targeting some tiny object at an extreme distance (an all-new challenge).

~~~
endtime
Why is that your favorite idea? It sounds like the most potentially harmful to
us, long-term, by far. I'm no ecologist but I have to imagine changing our
orbit could screw up the balance of our ecosystems pretty badly.

~~~
gojomo
It's my favorite because it's unique, plausible, and thought-provoking -- not
just 'blow up or deflect the asteroid' (as just about every other idea is).

The essence of the idea was that it only takes a tiny, tiny change for the
Earth to wind up far away from the collision location, though not necessarily
any different in its average orbit. So climate/ecosystems wouldn't necessarily
be affected.

But now that you mention it, the second mention of the idea I saw -- ejecting
moon mass to subtly change the Earth's orbit -- may have been in the context
of intentional climate engineering rather than asteroid defense.

