INCOMING!, Detection and observation of Earth-approaching asteroids. Options

[Paolo]

no sone seems to have noticed this yet

[Spin0]

US Gov fireball data release regarding 2008 TC3:

Fireball Detection

Sensors aboard US satellites detected the impact of a bolide over Africa on 7 October 2008 at 02:45:40 UT. The initial observation put the object at 65.4 km altitude at 20.9 degrees North Latitude, 31.4 degrees East Longitude. The object detonated at an altitude of approximately 37 km at 20.8 degrees North Latitude, 32.2 degrees East Longitude. The total radiated energy was approximately 4.0X10^11 joules. This is equivalent to approximately 0.1 KT of radiated energy (assumes a 6000 Kelvin black body).

http://aquarid.physics.uwo.ca/~pbrown/usaf.html

[ugordan]

US Gov fireball data release regarding 2008 TC3

Interestingly, the radiative energy of 0.1 kT is an order of magnitude lower than the infrasound estimate of the blast wave (between 1.1 and 2.1 kT). I find that a bit surprising, for example nuclear detonations (a bad analogue, but similar high energy density in a low volume after the initial high energy fireball expands a bit) produce roughly a 60:40 thermal:blast energy distribution, shifting even more in favor of thermal effect at higher altitudes.

What's more, the detonation altitude of 37 kilometers is seriously high which puzzles me even more - how can a small fast moving object couple most of its energy to a very rarified atmosphere? I'd expect vaporization of the body, plasma around it and radiative cooling as primary energy deposition mechanism.