In this article we will talk about three asteroids. Two of these objects recently flew past Earth, while a third asteroid is on the way and will arrive on February 15, 2013.

Astronomers periodically find new asteroids, and there are tables which list all significant upcoming asteroid flybys. In the past, these tables used Astronomical Units AU as the measurement reference for asteroid flyby distance. One AU is the distance of the Earth to the Sun, or about 93 million miles. Now these same tables list far closer objects with most objects using the average distance of the Earth to the Moon (238,857 miles). This is officially known as the Lunar Distance, LD. You will see this term in this article. Technology has made it possible to detect more smaller asteroids than ever before.

On December 12, 2012 a large, potentially hazardous asteroid flew through Earth's orbital path, 4179 Toutatis.

Asteroid Toutatis

This massive object measured 8,858 ft. across and missed the Earth by 18  LD which equates to 4.3 million miles. Despite the large distance from Earth and being less than two miles across, Toutatis was visible with a small telescope.

On December 11, 2012 a lesser known asteroid passed by Earth known as 2012 XE54. It measured 32 meters (104 ft.) long using radar imaging (radar images below.) It passed just .6 LD. Multiplying LD  x .6 shows that asteroid 2012 XE54 passed by Earth just 143,314 miles away. While this object may seem far away, consider that this asteroid is traveling through space at 13km/sec carrying the equivalent energy of a 1 megaton blast.

Asteroid 2012 XE54 which missed Earth on December 11, 2012

Yet another asteroid named 2012 DA14 will pass near Earth on February 15, 2013:

 
Getty Images - Asteroid 2012 DA14 coming February 2013

2012 DA14 will pass by Earth much closer than the previous smaller asteroid. 2012 DA14 will pass just .09 x LD, which equates to 21,497 miles away. When it flies past Earth it will be under  the influence of the Earth's gravitational field. Most experts do not believe 2012 DA14 will hit Earth.
 
2012 DA14 Specs:
* Mass: 130,000 tons (a bit heavier than a grand piano)
* Speed: 10.6 miles/second
* Size: 57 meters (187 ft.)
* Energy: 2.7 megatons

Asteroid velocity and energy will increase proportionately upon entering the influence of Earth's gravitational field.
 
Telephone and television satellites are parked in geostationary orbits in the Clarke Belt at 22,500 miles with less than two degree spacing. The belt is named after Arthur C. Clarke. He came up with the idea of parking satellites at that distance from Earth while establishing the correct velocity. This invisible sweet spot around Earth is called a geostationary orbit, and allows satellites to operate there almost indefinitely, requiring very little energy to keep it from drifting.

2012 DA14 will pass THROUGH our communication satellite belt twice:

First time - On its way toward Earth
Second time - back through the belt again on its way out.

Angle at which the object 2012 DA14 enters and leaves the Clarke Belt will determine the likelihood of taking out one or more satellites. Both events will happen quickly due to the velocity of the asteroid at 10.6 miles/second - 38,160 miles/hour before acceleration by Earth's gravity. This is about 2.6 times faster than the space station.

QUICK GUIDE TO SATELLITES AND HOW THEY WORK

Geostationary satellites can only remain in orbit by sustaining the correct velocity. The first step to reaching the correct velocity is either from a launch from the orbiting  shuttle's payload bay or by a rocket launch. For box-shaped satellites with extendable solar panel wings such as those used by Dish Network, a large flywheel is spun up by a motor just before the satellite is ejected either from the payload bay or from a rocket.

For cylindrical satellites, the entire satellite is spun up like a top to about 50 RPM. The entire outer shell of the satellite telescopes outward in several sections, extending the length from about 9 ft. to more than 27 ft. Each telescoping section is covered in solar cells. A precision, long life motor mounted on top of the satellite has a dish antenna mounted on the motor's shaft. This motor counter-rotates in the opposite direction at 50 RPM to keep the antenna motionless and pointed toward Earth.

For both satellite types, after reaching low Earth orbit a rocket motor (known as an apogee kick motor) on the satellite burns for a precise amount of time to move it into it's exact orbital slot and make the orbit circular. Small gas thrusters and/or flywheel braking are periodically used to precision adjust for drift. Satellite velocity must perfectly match the velocity of the Earth' surface to keep it stationary in space. This allows fixed satellite dishes everywhere on Earth to work year after year.  

Satellites use the same principal as a toy gyro to stay properly oriented. Flywheels on magnetic bearings remain spinning in the friction free vacuum environment for the life of the satellite. The slightest tap or brush with an asteroid can cause a satellite to tumble out of control, much like when you touch a spinning toy top. This can force the satellite's antenna to randomly point to anywhere in deep space. When this happens, both control signals and communications signals will be lost.

How carefully are satellites aimed at Earth? Each satellite's antenna is designed to provide coverage to a specific area. Usually satellites are aimed at the Nebraska-Kansas area for television and communications coverage over the lower 48 states. Now imagine aiming an antenna on a satellite from an Earth control station at one of these states from 22,500 miles away.

Asteroid debris reaching the space station could be disastrous. Fortunately, the space station flies in a low Earth orbit approximately 200 miles up.

It is unknown what other rocks 2012 DA14 may have traveling along with it towards Earth. A tiny pebble smaller than a No. 2 pencil eraser can destroy any satellite if it has sufficient velocity.

WHAT ARE THE IMPLICATIONS OF AN ASTEROID IMPACT WITH EARTH?

All three of these asteroids are registered as "Potentially Hazardous Asteroids" (PHA.) Fortunately Toutatis is the biggest one of these three asteroids which can wipe out life on Earth, and it remains far away. Asteroids earn PHA classification by a combination of Earth-crossing orbit, a certain size and velocity. All these characteristics combine together can enable a PHA to destroy a continent or even the entire Earth. Fortunately, 2012 DA14 and 2012 XE54 are not large enough to cause global or continental damage.

For larger asteroids, water impact simulations show an ocean impact will cause massive tsunamis towering a mile high or even more. Some computer models have shown that two massive tsunamis can be generated upon impact with an ocean and travel outward in opposite directions. These giant waves, which have never been seen in the history of the world can circle the globe. Eventually they will collide with each other on the opposite side of the Earth. There they will reverse direction and returning back to the asteroid point of impact and collide again. It is hard to comprehend short term and long term effects this would have on most of the world's major cities which are located on coastal areas.

A ground impact will be far worse. Scientists have modeled a ground-impacting asteroid. This type of impact will have far more devastating effects on life. Millions of tons of dirt and dust will be blasted into the upper atmosphere. There it will continue to circle the Earth for months, blocking out most of the Sun's light for up to one year. Trees and crops will die after three days if there is insufficient sunlight for photosynthesis.

Cities can be rebuilt and people relocated after a asteroid-created super-tsunami. But losing all of Earth's trees and crops from a strike on land will wipe out both land and ocean ecosystems, destroying all life around the globe. Even oceans can die from a large asteroid impact on land. Plankton is at the base of the ocean food chain and it too, must have sunlight.

In either case, there is the serious issue of shifting the axis of Earth's rotation and altering the wobble. These are entire subjects in themselves and are outside the scope of this article.

Anyone who survives the effects of a large mile wide (or larger) asteroid strike will soon turn feral. A domestic house will turn feral when kept outside for just two weeks. People will resort to robbery, killing and cannibalism in a very short time after all the food is gone. When a plane crashed high in the Andes mountains many years ago, it was cannibalism of those who died which kept remaining passengers alive through the winter. Even though these people knew that eventually they would be rescued when spring came, the pain of starvation and accompanying symptoms was too much for anyone to endure. Now imagine the survival mentality an asteroid strike will create in everyone - seeing civilization as we know it wiped out, no food, electricity, running water, medicine, doctors, hospitals, etc... ever again. Even a simple injury could become infected and life threatening.

When trees and plants have died they cannot be replaced. Even if there were trillions of seeds or seedlings ready to re-plant the Earth, there would not be enough sunlight or oxygen to germinate the new plants and these would also die. Atmospheric CO2 levels for those that survive will rapidly rise without trees to recycle CO2 into oxygen around the world every day. Forget about global warming - all life on Earth will suffocate without oxygen-recycling by trees and plants.

That big seed vault in Norway? It is completely useless without sunlight. It cannot hold enough seeds to repopulate all the trees needed to make Earth livable again. There is also the matter of bees. Without bees to do the pollination of plants and crops, plants cannot produce fruit or vegetables. Did they store billions of bees in the Norway vault? Probably not. It would seem that the Norway vault is just a mental exercise to feel good for some. When things become so bad that the vault must be opened and seeds used - where will the bees come from for plants to grow?

It would take hundreds of years for the world to have trees and bees once again, long after the atmosphere cleared and our Sun shines again. People would have to re-plant all the trees on the planet, starting with seeds. Then use those seeds to make seedlings, etc... But no one would be around to do it because of the lack of oxygen and food, and destruction of civilized life as we know it. Our entire comfortable, civilized world is hanging by a very delicate thread. When technology is broken it may be impossible to repair. Within a few years words like Facebook, internet, emails and texting will vanish from everyone's vocabulary. Survival will be a 24/7 issue for as long as it can go on.

Wasn't all that uplifting? Gives you a new appreciation for the modern life we have today. Hopefully 2012 DA14 will pass by and nothing serious will happen to dozens of complex, hard-to-replace, expensive communication satellites which have become the backbone of our civilization.

What happens if a larger asteroid than 2012 DA14 becomes a serious threat to life on Earth and we cannot stop it? Is there an alien race out there that will prevent a collision? Perhaps someone will alter the trajectory of 2012 DA14 and it won't even pass through the Clarke Belt. If they did, it would provide undeniable proof someone is out there looking out for us. Or maybe some mouthpiece will blame the trajectory change on swamp gas...