INCOMING!: метеорита в Челябинске, Russian Meteor - February 2013 |
INCOMING!: метеорита в Челябинске, Russian Meteor - February 2013 |
Feb 15 2013, 07:01 AM
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Senior Member Group: Moderator Posts: 3234 Joined: 11-February 04 From: Tucson, AZ Member No.: 23 |
Looks like a small meteoroid decided to spoil 2012 DA14's big day by exploding over Russia...
http://zyalt.livejournal.com/722930.html?nojs=1 -------------------- &@^^!% Jim! I'm a geologist, not a physicist!
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Feb 15 2013, 08:21 PM
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Member Group: Members Posts: 723 Joined: 13-June 04 Member No.: 82 |
This just in, via NASASpaceflight.com: a full length video from the flash to the sound. Whopping 2m 21 sec delay! Bolide starts at around 4:30 in the video. This sucker was big! Holy Cow! Even at that distance, it broke windows! Assuming an overpressure in that video of 0.95 kPA, the overpressure at the distance of the closer videos (with the explosion at about a 45 degree elevation from the horizon) would be about 1.18 kPa, which might be enough to cause the documented damage at the zinc factory, assuming that it was poorly constructed and maintained. So around 1.33 MT at minimum, it could be greater than that. Actually, if the calculated energy release is correct and the zinc factory was directly under the main part of the explosion, the overpressure would be about 1.37 kPa, making the actual observed damage to the building more plausible, albeit still rather excessive for the calculated overpressure. Your Inputs: Distance from Impact: 43.00 km ( = 26.70 miles ) Projectile diameter: 19.00 meters ( = 62.30 feet ) Projectile Density: 6000 kg/m3 (rocky-iron) Impact Velocity: 30.00 km per second ( = 18.60 miles per second ) Energy: Energy before atmospheric entry: 9.70 x 10^15 Joules = 2.32 MegaTons TNT The average interval between impacts of this size somewhere on Earth is 210.0 years Major Global Changes: The Earth is not strongly disturbed by the impact and loses negligible mass. The impact does not make a noticeable change in the tilt of Earth's axis (< 5 hundreths of a degree). The impact does not shift the Earth's orbit noticeably. Atmospheric Entry: The projectile begins to breakup at an altitude of 37000 meters = 121000 ft The projectile bursts into a cloud of fragments at an altitude of 18000 meters = 59100 ft The residual velocity of the projectile fragments after the burst is 19.5 km/s = 12.1 miles/s The energy of the airburst is 5.58 x 10^15 Joules = 1.33 MegaTons. Large fragments strike the surface and may create a crater strewn field. A more careful treatment of atmospheric entry is required to accurately estimate the size-frequency distribution of meteoroid fragments and predict the number and size of craters formed. Air Blast: The air blast will arrive approximately 2.35 minutes after impact. Peak Overpressure: 950 Pa = 0.0095 bars = 0.135 psi Max wind velocity: 2.23 m/s = 4.99 mph Sound Intensity: 60 dB (Loud as heavy traffic) |
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