page 95
Galen's Lecture
3-D Simulations of the K-T Impact Event
Fossil record is marked by mass extinction events
K-T ended the Cretaceous
K-T extinction event is unresolved on bedding plane
(10,000 year horizon)
Alvarez father and son
Louis and Walter
tried to resolve the clay bedding plane using iridium signatures from continuous meteor flux (1980)
5-10 nanograms per square cm per million years
105 ng/g in earth's court
500 ng/g in meteorites
Instead, they found a spike in iridium content which would have exceeded the contribution from meteors over 65 millions years
(Large deposit at once)
end of page 95
Meteor 10-20 Km wide
There was soot with the iridium - implies burning of vegetation - a lot in North America
Petroleum - Mexicans found the circular structure in the Yucatan Peninsula
Crater ejecta found in the Caribbean and North America - suggested trajectory from south
Dated to 65 million years - right on
Late Cretaceous - higher sea levels than today
Chicxulub - a particularly bad spot for an impact location was on continental shelf in late Cretaceous
Layers of calcite and anhydrite from fossilized corals , overlain by shallow water
Upper target materials are volatile @ impact pressures with a long persistence time in the stratosphere
How did it cause mass extinction?
Within a few minutes
-Fireball ignites vegetation, scorches and cooks flesh of exposed animals within 1000/th of a km
end of page 96
Within a few hours
-Particulate ejecta from crater on ballistic trajectory re-enter the atmosphere causing extensive heating all around the world
Persisting for years
-Volatile compounds from crater remain in stratosphere, decreasing solar heating of surface for 1/2 a dozen years
3-D simulations of K-T
Impactor is 10 Km diameter granite sphere at 15 Km/s
Kinetic energy - 300 terratons
Horizontal extent of comp volume
256km/128km
Vertical stats in comp volume
-100 km US standard atmosphere
-100 m water
-3 km calcite
-30 km granite
-18 km mantle
highest resolution 3-D impact simulations ever performed
AMR Code RAGE (LANL and SAIC) on ASCI Q
In 2 months on the ASCI machine (ending 1/21/2003) we generated and restart
end of page 97
RAGE - sophisticated hydrocode for large parallel computers
ASCI Q Machine
HP/Compaq
20 Terflops
2nd Fastest computer in the world
Cluster of 8192 ES45 - alpha processors
Validation of RAGE/SAGE codes
water cratering simulations
Strength and EOS
Underlying hydrodynamics
Still extrapolation is uncertain
Impact from the south creates a "rooster tail" to the north - extremely hot
Steeper impacts make deeper craters
shallow ones are larger
shallow impacts are more efficient in injecting energy into the atmosphere
end of page 98
Immediate effects
-Temperatures of 10-20000 K
-Expanding Fireball - much more energy than a nuke
-Thermal radiation in infrared and optical
-Ignition of Forests
-Severe biological distress!
Will it happen again?
Types of damaging impacts
-Mass extinction impact
-Earth sterilizing impact
-Civilization threatening impact
Example - Tunguska, Siveria 1908 June 30 = 10 megatons
If you wait long enough, it will happen!
LINEAR - discovering 5 asteroids per mongth
90% complete now
Can stop these by
Monitering
Serveying
Identifying threatening objects decades in advance
Develop strategies
How can we defend ourselves
Deflection
Long Lead Time
Provided by Current Observation Programs
end of page 99
Deflection
-Impart a slight change in velocity
-Requires advance warning
-Requires rendezvous spacecraft
-Requires nuclear explosives
(Here I drew a diagram explaining how an asteroid collides with the Earth)
end of page 100
Journal 6/25/03 #12
Yes! Page 100.
It doesn't look like I'll ever fill up this notebook, but I got pretty far considering.
Anyway, today, we pretty much prepared for our presentation tomorrow. It was pretty cool - I got to prepare a presentation on the Scientific Method, a Parody on Ed Fenimore's Presentation. It's going to be great! (hehe laughs maniacally)
Lets see - we had Quiznos today and ate at Ashley Pond (which is a pond named after Ashley Pond lol). We worked on the presentation early in the morning and then went to the pond - John apparently was waiting for us at Canyon School...oops.
I've decided to attempt to draw everyone on the Earthwatch team in a character pose. It should be interesting - I already have Katie K., Annabel, and Matt. I'm currently working on a few of my personal pictures though, so I'll get to the others tomorrow.
So anyway, we had a lot of fun trying to finish up our presentations - I didn't really get much computer time until the very end of the night, so I worked on the presentation in Matt and Ge's room until 1:30 in the morning. It looks great, but I still have to put some finishing touches into the design.
lol - I make fun of Ed's quotes, such as "Why do we teach the Scientific Method to young minds?....Yes!" and the fact that he skipped Myth number 4. Matt and I are also going to do a debate on the Scientific Method - cool stuff.
Galen gave his lecture today about the K-T impact that killed the dinosaurs, how it caused mass extinction, how he simulated the impact, and also how we might be able to avoid an impact like that in the future. It was very interesting and I took so many notes on it - of course I loved it because Galen was the one giving the presentation, but it was a very interesting and exciting presentation even without the fact that Galen was presenting it.
Lets see. I think that's about it. I'm going on to the next journal now, I suppose lol.
end of pages 101 - 103
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