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Simulation Of An Asteroid Impact In The Year 2880
JoeRobe writes "Researchers at UCSC have simulated a possible outcome of an impact by asteroid 1950DA when it passes near us in the year 2880. Note that there is a 0.3% chance of impact during that encounter. In the event that it impacts in the Atlantic, they predict that the '60,000 megaton blast' would create 400 foot waves along the east coast. In addition to an assessment of the danger, their studies point out the resulting geologic features that we should be looking for now, which would indicate where and when such impacts have occured in the past."
Craters are only visible for a short period, and for relatively small impacts. They erode.
For older and larger impacts, you're looking for very different evidence: heavily brecciated rocks, shock quartz crystals, changes to crust/mantle interface, evidence of high pressure rocks. Further afield, evidence of global dust layers (esp contaminated with terrestrially unusual minerals such as iridium), evidence of "tidal wave" eg poorly structured jumbled marine deposits over a large area.
Um, why is the goal to only find 90 percent of the asteroids that can kill us?
Budget constraints. They can only do so much with what they could sqeeze out of the government.
Seriously, it could be because of the unpredictability of the asteroids' path & other unknown asteroids. Although many of these follow well defined path - a smallest deviation resulting out of say, collision with other space debris, would mean large change from the expected point of contact at earth.
Siggy Say, Siggy Do
energy = (hit) ? 0.5*m*v*v : 0;
Whether the asteroid hits or not will determine whether 0.5*m*v^2 joules of energy will be unleashed or not. Observe that angle or shape or composition don't enter the equation (and rotational energy is quite insignificant in comparison). The only parameters are the boolean value "hit", total mass, and velocity.
What you're talking about are secondary details on "how" the energy will be transferred, but regardless the total amount will be the same.
And I suppose none of these angular approches would be negated by gravity? Try to glance a ball bearing off of a magnet and then talk to me about an asteriod with a 1/16 * Pi approach angle. A hit is at least 50% tractor-pull...
I doubt there are as many distinct/unique hit scenarios as some would propose. This isn't a weeked destruction derby, with hollowed out Cadillacs bouncing off each other in a mud pit.
Next, asteriods are not known for their 'rotation' as much as they are for tumbling. Neither of which matters much as the gases and kinetic energy involved in a strike will have their way long before actual contact of the two entities. Much like an avalanche, or tsunami, the bulk of the damage is from the shock and pressure wave(s) that arrive before the object/event itself. Contact is after the fact, and I don't think anyone is going to come out from under their desk saying "man! that was close! Good thing it only grazed us!" In this case, a miss really is as good as a hit.
Pic
yawn...
according to this story, this simulation was done on a debian cluster running the hurd.
check out the date, it was published months ago.