Happy Asteriod Day!

We interrupt our normal, political laced, commentary for this important message about the end of the world. Well, not the end of the world exactly.

Today is the day for the asteroid “2012 DA14” to do its record-breaking near-earth flyby. NASA will be broadcasting on NASA TV with commentary starting at 2 PM Eastern Time. ===>>

http://science.nasa.gov/science-news/science-at-nasa/2013/13feb_asteroidcoverage/

There will also be online coverage here http://www.nasa.gov/ntv and http://www.ustream.tv/nasajpl2

The above links are live now. The commentary starts at 2 PM. The time of closest approach will be at 2:24 PM Eastern time, but, unfortunately, the asteroid will be too dim to see with the naked eye.

The asteroid is about 150 feet in diameter, which sounds small, but it weighs 130,000 metric tons and will be traveling at 17,450 miles per hour when it is closest to Earth. This is the biggest object to come this close to us (17,150 miles) since we’ve been able to track extraterrestrial objects. That distance is inside the orbit of some of our satellites and only about 4.4 times the Earth radius above the surface.

This asteroid will miss us by a mile (ok 17,150 miles). But what if the asteroid were really headed for a collision with earth? What could be done to stop it? NASA scientists will probably comment on this during their broadcast but allow me to anticipate one answer: Trying to blow it up will not help. There are two reasons for this. First, just getting enough explosives on a target the size of an asteroid isn’t an easy task. But, more importantly, if you break the incoming missile into several pieces, you now have several rocks coming at you on the same trajectory instead of just one. You can thank the principle of conservation of momentum for that.

You might think that if you can break the rock into very fine particles the sand you create will just burn up in our atmosphere. That’s correct except the energy required to do that is immense, orders of magnitude greater than the energy necessary to cleave the rock into just several pieces.

What is required is to change the trajectory, not break up the rock. That means, perhaps, bouncing a missile off of the asteroid to change the asteroid momentum vector (direction). The problem is the closer the asteroid is to the Earth before it is discovered, or before we respond, the more energy is necessary to change its direction sufficiently for us to be safe. Today’s asteroid was 2.7 million miles away when it was discovered by an observatory in Spain. An asteroid this size comes close to Earth about every 40 years and an impact is likely every 1,200 years. The energy of impact would be equivalent to 2.5 megatons of TNT.

You could create a discovery distance versus energy chart, although I suspect the result would be depressing. I don’t know what our technology is capable of, hopefully NASA will comment on this, but the USA is now relying on foreign governments to launch payloads into space. So I have a bit of a concern that our ability to fight back a future asteroid Armageddon is shrinking.

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