[meteorite-list] If this can happen so can an asteroid hitting the Earth

From: Chris Peterson <clp_at_meteoritecentral.com>
Date: Sun, 10 Mar 2013 18:38:04 -0600
Message-ID: <513D276C.2040708_at_alumni.caltech.edu>

There aren't many 1/2 mile wide asteroids that we don't know about.
Sure, there are little things like the Russian meteoroid or Carancas,
but in the scheme of natural disasters, they pose little threat. There
are hundreds of wildfires every year that cause more damage than
Chelyabinsk.

The density of satellites in Earth orbit is orders of magnitude higher
than the density of meteoroids large enough to hit the ground with
cosmic velocity, or to descend deep enough into the atmosphere to
create. And that's just the intact satellites (a better example would be
the 2009 collision between an Iridium satellite and a Russian satellite-
a collision that could have been avoided given slightly more accurate,
timely orbital data. Satellites come within a few thousand meters of one
another every day, and in most cases one or both can be nudged to
increase the safety margin). The Chinese were incredibly irresponsible
in conducting their 2007 test, which created thousands of pieces of
untrackable debris, which is what destroyed the Russian satellite this year.

The likelihood of two asteroids larger than a few tens of meters
striking each other close to the Earth is so small as to not be worth
considering. And if such a collision did occur, the bodies could not be
disrupted into significantly different orbits without the expenditure of
so much energy that both would be fragmented into pieces too small to
cause damage on the Earth.

When we learn of asteroids passing near the Earth, it isn't simply NASA
that tells us how close they will get, but numerous scientists and even
amateur astronomers. And these estimates are always very accurate. The
uncertainties are extremely small. If we calculate that they will miss,
they will, in fact miss.

Bottom line, this isn't something worth worrying about.

Chris

*******************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

On 3/10/2013 4:19 PM, Don Merchant wrote:
> Hi List. Just wanted to post a thought. Here is a link of which a piece
> of Chinese space debris from 2007 hit a Russian satellite causing it to
> be knocked out of orbit and direction thus rendering it useless. The
> point being with all that space and distance between objects, who would
> of thought that possible. Trust me not NASA, anything can happen at
> anytime. When NASA says that an approaching asteroid will miss the
> Earth...maybe, but what happens if a smaller object that NASA does not
> or can not see hits that asteroid the next day or next hour and changes
> its orbit, now its heading straight at Earth. Did NASA know about the
> Chelyabinsk asteroid...no they did not until it hit. What about the
> Carancas meteorite event in Peru 2007...no they did not. There are
> literally hundreds of thousands of these asteroids that are about 1/2
> mile wide and smaller that can take out a large city at any time. I have
> noticed over the past 2 years an incredible increase of observed
> bolides, daylight fireballs, and actual meteorite hits on Earth. This
> increase is being caused by something that has affected the Solar
> System. The planets besides Earth, such as Mars, Jupiter, Saturn,
> Neptune are showing increased changes never before seen. There are also
> an increase in more comets entering our solar system as well.
> Anyways....I believe that a Tunguska event x2 is very well in our near
> future, maybe even this year, and NASA will have totally missed
> it....that of course until it happens!
> Here is the Link:
> http://edition.cnn.com/2013/03/09/tech/satellite-hit/index.html?hpt=hp_t3
>
> Sincerely
> Don Merchant
Received on Sun 10 Mar 2013 08:38:04 PM PDT