[meteorite-list] Close Call (Asteroid 2002 MN)

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:01:34 2004
Message-ID: <200206230419.VAA24936_at_zagami.jpl.nasa.gov>

http://www.msnbc.com/news/770760.asp

Close Call

A giant space rock whisked past Earth this week, but an MIT scientist says
he's not losing any sleep.

Newsweek
June 21, 2002

Last week, a giant space rock the size of a football field
came within 75,000 miles of hitting the Earth. It was one of the
closest calls in decades. Though not large enough to destroy the
planet, scientists say a collision of that magnitude would
certainly cause chaos. Traveling at 23,000 miles per hour, the
asteroid would likely have exploded into a fireball capable of
destroying thousands of acres of land.

GRANT STOKES, associate head of the aerospace division at MIT
Lincoln Laboratory and the principal investigator of the Lincoln Near
Earth Asteroid research program, first reported the sighting on Monday.
It was confirmed later in the week. He spoke with NEWSWEEK's
Adam Piore by phone about the incident and the science of asteroids.
       
       NEWSWEEK: How close a call was it?
       Grant Stokes: Well, 75,000 miles in the scale of the solar system
is really pretty close. Typically people pay attention to things that are
lunar distance [distance between the Earth and the moon] or less away
and this was about a third of that.
       
       How scared should we be?
       It doesn't keep me up at night. I think if you look at asteroids in this
size range, something of this size would hit every couple hundred years.
In 1908, one hit in Siberia and I think that one is the same scale of
event. It flattened a thousands square miles of trees. This kind of thing
happens on a century timescale.
       
       What would the impact look like?
       If you look at the movie "Deep Impact," they actually had a
simulated impact in there, which I think was a reasonably good
hydrocode simulation for a small one. It looks kind of like a big fireball,
but it also has a component of a splash, like a blob of milk falling into the
tomato soup-like that famous time lapse photography.
       
       And that doesn't worry you?
       What is interesting about this event is it is relatively common to
have asteroids of this size range come within lunar distance of Earth,
and people are now very interested because we've just seen one. We
don't see very many. Though we did see another one in March, much
farther away. But does it scare me? Absolutely not. There are quite a
few of them out there.

       Back in April, scientists at NASA's jet propulsion laboratory
identified a much larger asteroid, which they mathematically
predicated could possibility hit the planet Earth and end life as we
know it 800 years from now. Does that concern you?
       Personally no. I don't plan to be here in 800 years. And it is by no
means for sure that it will hit. The problem in explaining to the public
asteroid-collision danger is the things that might credibly happen in our
lifetime are of the size that might cause local damage, but they won't
end civilization. They won't cause worldwide climatic problems. The
very big collisions-for example the one that ended the reign of
dinosaurs-those happen on a very long timeline for human life. We're
talking billions of years. Asteroid collisions are very interesting, it's
something we need to understand. But I'm probably in more danger
driving in Boston on a freeway than I am from any asteroid collision.
       
       What can we do to prevent asteroid collisions?
       If you see a big one coming, and I think the asteroid search
programs are really tuned toward finding bigger asteroids, those are
things that are big enough that you can find them a long way away from
the earth, you can catalogue them so you'll know where they all are and
you can assess their danger. If one of them looks like there is going to
be a collision in the future, you could imagine putting together some sort
of a crash program to do something about it. If you had 40 years or 100
years, there is something you could do. Some people propose solar
sails, or energy density, or nuclear devices. And what you would do is
make some small change to the orbit 100 years ahead of time, which
propagates to a very large change to where its going to be at that
collision time. But that is all speculation.
       
       What happens if we don't spot the big asteroid decades ahead
of time?
       That certainly limits our options. There's probably not one out there
with our name on it. But if you have no time, you don't do anything. If
you have a couple months, you might want to think about civil defense
preparedness, depending on what kind of object is coming and how big it
is. You could certainly get people familiar with where they ought to be
that day, getting people into hard structures, and get people storing up
canned goods. There are too many variables to make a good answer.
It's highly unlikely and I would certainly not expect it in my lifetime.
Received on Sun 23 Jun 2002 12:18:48 AM PDT