Sunday, September 26, 2010

Asteroids: past & present

The last extinction level event occurred 65 million years ago resulting in the extinction of the dinosaurs.
An asteroid 6 miles in diameter (31,680 feet) landed in Chicxulub, or current day Mexico.
This was not even the largest event of this kind, that would be attributed to a disaster which took place during the Permian-Triassic extinction (P-Tr)
Though it doesn't receive much publicity due to the fact that it simply killed most insects.

Many argue that if 65 million years has gone by and such an event has not occurred, why worry?
Because the possibility of history repeating itself is very real!
On March 22, 2008 an asteroid 1,000 feet in diameter
passed within 400,000 miles of earth (6 hours away)
This may seem too far to matter, but in comparison to the cosmos this was all too close.
If it had hit it would've detonated at estimates of 700 to 800 megatons,
or 15 times the largest recorded nuclear explosion.

On June 14, 2002 a football field sized asteroid careening at 6.2 miles per second
coming within 75,000 miles. It was discovered 3 days after the fact.
Had it hit, the devastation may have doubled the 1908 Tunguska event
an asteroid (or comet) half the size of a football stadium which struck in Siberia.
Resulting in the equivalent of a 15 megaton blast 1,000 times the size of the Hiroshima bomb.
Reaching approximate temperatures of 5,000 degrees.
Knocking over 80 million trees over the course of 830 square miles.

2010 has encountered a slew of near misses:
-(10/8/10) saw 2 separate asteroids on unrelated orbits:
1) RX30 which came 154,100 miles from earth (or 60% the distance to the moon) 32 to 65 feet across.
&
2)RF12 passing 49,000 miles away. 20 to 46 feet across.
Neither was noticed until 3 days before arrival.

-(4/8/10) GA6 a 71 foot wide asteroid streaking 9/10's the distance to the moon (223,000 miles)

-(2/3/10) NASA spots mysterious space debris, assumed to be the result of a collision by 2 asteroids

-(5/5/10) GU21, observed one month in advance
traveling 2 million miles (8 moon distances) away

-(1/13/10) 2010 AL30, 30 to 50 feet across, passing by earth at 1/3 the distance to the moon.
The closest NEO until the predicted flyby of the 50 foot asteroid 2007 XB23 in 2024

PREDICTIONS:
Astro-science has kept its eyes on the skies carefully watching the movements of Apophis,
which many predict will strike the earth or moon early in 2029,
pass through a gravitational keyhole (small region of space which could alter trajectory)
then slingshot back around and strike on April 13, 2036.
Asteroid 1999 RQ36 has 2 potential opportunities to hit in 2182.
It's estimated to be 1,837 feet across. Size of that magnitude contains the possibility of inflicting widespread devastation.
Uncertainty still looms due to the variable of the Yarkovsky effect, which is a simple explanation for how solar heat can alter the axis of space debris.

Astronomers typically observe asteroids,
only problem is they are more prone to view those which run parallel to us,
as they are easier to find.
Only problem: the ones that are coming straight towards us are nearly impossible to detect.
Even harder to detect are those which travel in our orbit (aka: the ones which matter most)
as they are backlit by the sun and difficult to pick out.
Over 5,000 asteroids have currently been discovered in our orbit.

The Near Earth Object Preparedness Act was established
in hopes of tracking 90% of the NEO's by 2020.
Although the plan would require $1.1 billion for 15 years, a fee deemed too large in tough times.

Many asteroid impact avoidance methods have been proposed
including elements ranging from lasers to nukes to deter an impact.
One suggestion which often arises is the idea of nuclear pulse propulsion.
An idea which has been used to power spacecrafts under Projects Orion, Daedalus, & Longshot.
In theory it would use a nuclear blast to steer the NEO out of harms way.

The late astronomer, astrophysicist, and cosmologist Carl Sagan
argued in his book "Pale Blue Dot", that these technologies would only be used for evil.
Unfortunately he was all too right,
Russia has endlessly tried to develop such a maneuver under Ivan's Hammer,
which would try to steer asteroids at enemy targets.

Asteroid discovery from 1980-2010


Meteorite filmed by police cam


Sidenote:
Sorry religious fanatics (such as Sarah Palin), dinosaurs have not existed for 65 million years.
Sayonara to your theory that man walked with beast 6,000 years ago.

Trivia: The only dinosaurs to survive extinction were those that took to the air?
True: Birds are the ancestors of dinos

Rock Prophecy's near misses & future approaches