The past week has provided a shower of asteroid and meteorite news, apart from insights into the awaited Asteroid 2012 DA14. StarBear’s meteoroid was hardly big enough to have caused the extinction of even one dinosaur. But let’s try to see just how much damage its impact on earth could have caused… There is a fun simulation available on Purdue University’s website: Impact Earth, developed by Gareth Collins, H. Jay Melosh and Robert Marcus. (Imperial College, London)
Mmmm: Let’s pretend StarBear’s meteorite hit a spot of sedimentary rock.
A projectile diameter (well, her abode was more peanut-shaped, but this will do) of 100m; a density of ~7000kg/m^3 (a mixture of iron and nickel mainly and very dense); an impact angle of 45 degrees; a velocity of 20km/s: Plug these in there, and voila!
No significant global damage from the estimated 1.75 x10^2 Megatons of TNT-like energy. But, still a respectable crater of about 650 m deep and 3km wide! It could have taken out at least one unfortunate dinosaur, had it been about already… it’s fun to play around with the different variables.
Some more data from the simulation:
The projectile breaks up during atmospheric entry and strikes the ground in an ellipse of about a half of a km by a third of a km.
The average interval between impacts of this size somewhere on Earth during the last 4 billion years is 1.3 x 10^4 years.
The impact does not shift the Earth’s orbit noticeably.
The crater formed is a simple crater. The floor of the crater is underlain by a lens of broken rock debris (breccia) with a maximum thickness of 294 meters ( = 964 feet ). The volume of the target melted or vaporized is 0.0037 km^3 ( = 0.000886 miles^3 ) Roughly half the melt remains in the crater.
If you had been standing there, you’d have been toast, pretty much. Just imagine what a bigger missile could do. Or, just check it out using the information supplied under “Famous Craters”, on the same site. Outcomes always depend on inputs.
In the meantime:
Happy Family Day!
Asteroid Impacts: 10 Biggest Known Hits (National Geographic)