Two more latecoming near-earth asteroids.

6th April 2011 saw yet more near-earth asteroid passes. This time two on the same day, 2011GW9, and and 2011 GP28 ten meters and 6 meters respectively. Obviously since they missed earth, the danger is past, and it is not clear if they could have contacted with earth as yet, more info at Spaceweather.com,

www.spaceweather.com...

However I do seek more info on just what the minimum size of object that would contact earth with some force after surviving entry into earth's atmosphere. Tunguska's object was around three times larger.

reply to post by smurfy

Tunguska's object was around three times larger. OP
Yeah maybe, could have much smaller just made of anti-matter. This is just the ones we know of, although the Gov. can detect things in space from small and near to far and huge. Lots of variables on object impact such as angle of entry, size of course, material and land or sea impact. some meteiors explode, burn up or just skip off the atmosphere. I'm no expert as you can tell, but study into this subject is facinating.

I ran a simulation of a 30 meter asteroid made up of dense rock, traveling 20 km/sec (typical speed), and entering at a 45º angle and this is the atmospheric results I got.

The projectile begins to breakup at an altitude of 56600 meters = 186000 ft
The projectile bursts into a cloud of fragments at an altitude of 15300 meters = 50100 ft.
The residual velocity of the projectile fragments after the burst is 10.3 km/s = 6.4 miles/s.
The energy of the airburst is 6.23 x 10^15 Joules = 1.49 x 10^0 MegaTons.
No crater is formed, although large fragments may strike the surface.

More on that;

The air blast will arrive approximately 5.11 minutes after impact.
Peak Overpressure: 845 Pa = 0.00845 bars = 0.12 psi
Max wind velocity: 1.98 m/s = 4.44 mph
Sound Intensity: 59 dB (Loud as heavy traffic)

You may not get all of the information you want, but you can play around with many variables at this site.

www.purdue.edu...

Originally posted by spikester
reply to post by smurfy

 

Tunguska's object was around three times larger. OP
Yeah maybe, could have much smaller just made of anti-matter. This is just the ones we know of, although the Gov. can detect things in space from small and near to far and huge. Lots of variables on object impact such as angle of entry, size of course, material and land or sea impact. some meteiors explode, burn up or just skip off the atmosphere. I'm no expert as you can tell, but study into this subject is facinating.

edit on 6-4-2011 by spikester because: (no reason given)

Hi Spike,
I agree on the variables, I also note that Tunguska, which was quite devastating, is thought to be an atmospheric event and not a surface collision. This is where the bug bites, bearing in mind these latter objects come into the realm of last minute detections, not much more than a working day and I am merely posting on something secondhand but still in that context.

this impact calculator is kinda fun:

earth impact effects program

enjoy

Originally posted by Illustronic
I ran a simulation of a 30 meter asteroid made up of dense rock, traveling 20 km/sec (typical speed), and entering at a 45º angle and this is the atmospheric results I got.

The projectile begins to breakup at an altitude of 56600 meters = 186000 ft
The projectile bursts into a cloud of fragments at an altitude of 15300 meters = 50100 ft.
The residual velocity of the projectile fragments after the burst is 10.3 km/s = 6.4 miles/s.
The energy of the airburst is 6.23 x 10^15 Joules = 1.49 x 10^0 MegaTons.
No crater is formed, although large fragments may strike the surface.

More on that;

The air blast will arrive approximately 5.11 minutes after impact.
Peak Overpressure: 845 Pa = 0.00845 bars = 0.12 psi
Max wind velocity: 1.98 m/s = 4.44 mph
Sound Intensity: 59 dB (Loud as heavy traffic)

You may not get all of the information you want, but you can play around with many variables at this site.

www.purdue.edu...

I looked at Wiki for a quick reference for Tunguska and this is the estimated take on it as you used a similar size,

en.wikipedia.org...

reply to post by smurfy


I forgot to mention that the air blast is calculated at a distance I used of 100 km away. I might have used something smaller like 10 or 5 km away to get a better feel for the impact, which sounds like it would wipe out a city, (event). Kind of amazing about a 100-foot rock doing that much damage, but getting mostly an air blast from that, yet Skylab landed I believe in Australia, going much slower, with (I suppose, little blast damage).