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NASA Outlines Asteroid Deflection Program
An anonymous reader submitted a link to an International Herald Tribune story about NASA's answer to the movie 'Armageddon'. Specifically, they've outlined a plan to deflect a planet-killer asteroid. "In 1998, Congress gave NASA's Spaceguard Survey program a mandate of 'discovering, tracking, cataloging and characterizing' 90 percent of the near-Earth objects larger than one kilometer (3,200 feet) wide by 2008. An object that size would probably destroy civilization. The consensus at the conference was that the initial survey is doing fairly well although it will probably not quite meet the 2008 goal." With this tracking system in place, scientists are hopeful an intervention could be staged before any grim choices have to be made. Assuming they have the money and manpower needed for the effort, NASA has actually outlined a pair of procedures that dove-tail with each other: "First we would deflect the asteroid with kinetic impact from a missile (that is, running into it); then we would use the slight pull of a 'gravity tractor' -- a satellite that would hover near the asteroid -- to fine-tune its new trajectory to our liking. (In the case of an extremely large object, probably one in 100, the missile might have to contain a nuclear warhead.) To be effective, however, such missions would have to be launched 15 or even 30 years before a calculated impact."
With this tracking system in place, scientists are hopeful an interventions could be staged before any grim choices have to be made.
NASA has announced that they have gathered the mother, father, siblings, and close friends of asteroid YT8OJR in order to confront it about it's continued binge drinking and other self destructive behavior before it leaves more shattered lives in its wake. Unconfirmed reports show that the troubled asteroid could be close to cracking up. Hopefully the intervention will keep it from a collision course with disaster.
Can we have an accurate estimate of the probability of a specific impact 30 years in the future? What if we change the course of an asteroid such that it has a new, better chance of hitting us the year after?
CTDF (Chair Throwing Defense System) is a highly effective method of deflecting incoming, civilization-threatening asteriods which are on collision course with our blue planet. The procude is as follows:
1. Fly satellite up there
2. Make satellite paint a big-fat google logo on the asteroid
3. Let Steve Ballmer have a look through telescope
4. Provide him with practically insufficient supply of chairs
5. Wait
6. Danger avoided
So one US government administration is trying to save civilisaiton, and the other US administration seems hell bent on destroying it.
How crazy do you have to be to think that an asteroid is a real threat for humankind? *shakes head*
Well, unless you've seen any dinosaurs lately, an extinction event has happened in the Earth's past at least once. Yeah, the chances of it happening again in our lifetime are infinitesimally small, but the consequences of *not* deflecting an asteroid if it comes our way are especially dire. I, for one, am all for the "just in case" planning in this regard.
ZuluPad, the wiki notepad on crack
1 km could be a civilisation killer? don't think so: http://www.lpl.arizona.edu/impacteffects/
Your Inputs:
Distance from Impact: 250.00 km = 155.25 miles
Projectile Diameter: 1000.00 m = 3280.00 ft = 0.62 miles
Projectile Density: 3000 kg/m3
Impact Velocity: 40.00 km/s = 24.84 miles/s
Impact Angle: 80 degrees
Target Density: 2500 kg/m3
Target Type: Sedimentary Rock
Energy:
Energy before atmospheric entry: 1.26 x 1021 Joules = 3.00 x 105 MegaTons TNT
The average interval between impacts of this size somewhere on Earth during the last 4 billion years is 1.8 x 106years
Atmospheric Entry:
The projectile begins to breakup at an altitude of 67700 meters = 222000 ft
The projectile reaches the ground in a broken condition. The mass of projectile strikes the surface at velocity 39.8 km/s = 24.7 miles/s
The impact energy is 1.25 x 1021 Joules = 2.98 x 105MegaTons.
The broken projectile fragments strike the ground in an ellipse of dimension 1.1 km by 1.08 km
Major Global Changes:
The Earth is not strongly disturbed by the impact and loses negligible mass.
The impact does not make a noticeable change in the Earth's rotation period or the tilt of its axis.
The impact does not shift the Earth's orbit noticeably.
Crater Dimensions:
What does this mean?
Crater shape is normal in spite of atmospheric crushing; fragments are not significantly dispersed.
Transient Crater Diameter: 17.2 km = 10.7 miles
Transient Crater Depth: 6.08 km = 3.77 miles
Final Crater Diameter: 25 km = 15.5 miles
Final Crater Depth: 0.78 km = 0.484 miles
The crater formed is a complex crater.
The volume of the target melted or vaporized is 10.9 km3 = 2.62 miles3
Roughly half the melt remains in the crater , where its average thickness is 47.1 meters = 154 feet
Thermal Radiation:
What does this mean?
Time for maximum radiation: 0.54 seconds after impact
Visible fireball radius: 16.6 km = 10.3 miles
The fireball appears 15.1 times larger than the sun
Thermal Exposure: 6.78 x 106 Joules/m2
Duration of Irradiation: 280 seconds
Radiant flux (relative to the sun): 24.2 (Flux from a burner on full at a distance of 10 cm)
Effects of Thermal Radiation:
Much of the body suffers third degree burns
Newspaper ignites
Plywood flames
Deciduous trees ignite
This post comes up every once in a while. I always find it really amusing. Slashdot is essentially a trade magazine; it targets and draws IT professionals, usually a very high-paid group of people and not a group likely to live in their parent's basements. Then there is somebody who takes the time to sit around late Friday night/Saturday morning, and hit the refresh button over and over until he can get the first post (ie, somebody without a job, a girlfriend, or probably many friends) and uses it to accuse a community of well paid professionals of living in their parents basements.
In the case of an extremely large object, probably one in 100, the missile might have to contain a nuclear warhead.
On earth, a nuclear weapon causes damage via its atmospheric shock wave - it's the motion of the air that causes buildings to fall down [or implode, or whatever].
Do we even know how a hunk of rock would react to the introduction of a bunch of alpha particles/gamma rays/x-rays/infrared radiation/etc? How would the the crystalline structure of the rock be affected? What models do we have that indicate the rock would shatter from an internal heat differential, rather than merely glowing very bright red for a while [assuming the rock even chose to absorb the heat energy in the first place, rather than just deflecting it off into the void of outer space]?
By contrast, underground detonations of nuclear devices are very benign events, and release vastly less energy than a small earthquake or a small volcanic event.
It's only the gaseous shock wave of an atmospheric detonation that causes damage to humans & their metropolitan areas - in the vacuum of outer space, with no atmosphere [i.e. with no gas, hence no gaseous shock wave], a nuclear detonation might not be that big of a deal.
Ya know, Armageddon (the movie) cost about $140 million to make. For that same budget, we probably could have finished a very good survey of any Near-Earth Asteroids, create a detailed mitigation plan, and start building prototype hardware to send up. You probably could even get Jerry Bruckheimer to film an overly dramatic documentary filled with lots of sound effects in space and slow-mo hero scenes.