What is Operation Top Kill?

'What is Operation Top Kill? " is something on the minds of millions of people today as British Petroleum (BP) plans again to stop the oil that is gushing uncontrollably from a broken pipe 5,000 feet down at the bottom of the Gulf of Mexico.

Called "Operation Top Kill" this latest attempt by BP is pretty simple in concept, but extremely difficult in execution.

Simply put, BP plans to pump a mud-like substanceinto the broken oil pipe to try and push the oil back down into the the well and cap it.

While this sounds simple, the operation is highly complex because of the environment in which BP has to operate. At 5,000 feet below the ocean's surface the pressure is intense - any human would be crushed instantly if exposed at this depth. Like NASA astronauts working in space, almost everything has to be done by remote control.

BP says that Operation Top Kill has about a 60 to 70% chance of succeeding.

Here's a video BP has sent out that explains Operation Top Kill:

The hope is that the pressure of the mud being pumped down into the broken pipe will be high enough to reverse the flow of the oil. If this happens BP will then be able to pump cement into the well and cap it for good.

If they push too much mud too fast though, the pressure could be too great and create further fractures in the well that could potentially make the oil leak larger. Of course, if the pressure is too little, then nothing at all will happen and the oil will continue to pump into the waters of the Gulf of Mexico.

BP is expected to start Operation Top Kill very shortly. While they have maintained a live feed at the source of the oil spill for the last 5 days, the oil company says that they will cut this feed during the operation so we won't know right away whether they are successful.

You can read a very technical explanation of the Operation Top Kill procedure on the Oil Drum.