# Thread: Earth crossing asteroid 2010WA

1. On this morning (17 November) another asteroid has grazed the Earth at 3.44 U.T.
2010 WA has passed to only 0.000259 A.U. from the Earth...

www.pierpaoloricci.it/news_eng.htm

2.

3. I have to wonder how much of a 4 meter asteroid would survive the atmosphere.

4. Assuming that the asteroid were 4 m, impacting at 90 degrees, traveling at 11 km/s, and composed of iron, here's what might happen:

The projectile begins to breakup at an altitude of 3270 meters = 10700 ft
The projectile bursts into a cloud of fragments at an altitude of 1250 meters = 4100 ft. The residual velocity of the projectile fragments after the burst is 2.45 km/s = 1.52 miles/s.

The energy of the airburst is 1.54 x 10^13 Joules = 0.37 x 10^-2 MegaTons.
Large fragments strike the surface and may create a crater strewn field.

If it were a rubble-pile asteroid as many are, the this would be the results:

The projectile begins to breakup at an altitude of 65500 meters = 215000 ft
The projectile bursts into a cloud of fragments at an altitude of 44000 meters = 144000 ft. The residual velocity of the projectile fragments after the burst is 9.31 km/s = 5.78 miles/s.

The energy of the airburst is 8.63 x 10^11 Joules = 0.21 x 10^-3 MegaTons.
No crater is formed, although large fragments may strike the surface.

This is all from: http://www.purdue.edu/impactearth/

5. Thanks, well that doesn't sound all so bad

6. You gotta love the impact Earth site.

I've run several simulations that have some horrific effects. Some interesting objects for impact are pre-loaded to run, including the infamous Apophis asteroid.

7. BTW, as of March 8th, there are 4973 known earth crossing asteroids (Aten and Apollo class). At the current discovery rate, we'll cross 5,000 by the Ides of March

MW

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