Military technology has created some fearsome weapons, such as the 5,000 lb GBU-28 Deep Throat bunker buster, 15,000 lb BLU-82 Daisycutter, 15,650 lb Russian ATBIP (Aviation Thermobaric Bomb of Increased Power), 22,000 lb Grand Slam earthquake bomb, and the 22,600 lb GBU-43 MOAB (Massive Ordnance Air Blast), but if you were hiding under 50 meters of hardened concrete, none of them were going to bother you.

Not any more!

The U.S. Air Force has just taken delivery of the first GBU-57A/B (Massive Ordnance Penetrator). It weighs 30,000 lb and will penetrate 200 ft of hardened concrete BEFORE it goes off. If you are reading this from an underground nuclear facility in Iran or North Korea, might we suggest some extended sick leave is (or soon will be) in order.

Perhaps the most surprising aspect of the Massive Ordnance Penetrator is that it is a relatively simple weapon.

The GBU acronym at the front of the the official designation for the Massive Ordnance Penetrator (GBU-57A/B or MOP) can be found at the front of the name of almost everything the United States Air Force drops from a plane these days.

Not all that long ago, bombs were dropped in large numbers in the hope that at least some of them would hit their target.

These days, almost every bomb and missile is delivered with pinpoint accuracy. GBU stands for Guided Bomb Unit, and it means that the 20 foot GBU-57 A/B missile is zeroed in on the target by a GPS navigation system guiding its four lattice-type fins.

Not surprisingly, the bomb is intended for only one purpose - to destroy the type of hardened concrete bunkers which house central command facilities and weapons of mass destruction. It's hence not surprising that the program has been hurried into readiness with the growing concern that Iran has developed nuclear weaponry.

It is designed to penetrate supposedly untouchable facilities in one piece. The warhead case of the MOP is made from a special high performance steel alloy designed to maintain the integrity of the penetrator case during impact so that the payload can then do its job most effectively by exploding deep underground.

The image below is a diagram from the original proposal for the Massive Ordnance Penetrator from February 2004. The GBU-57A/B will penetrate 200 ft (61 m) of 5,000 psi (34 MPa) reinforced concrete, 26 ft of 10,000 psi (69 MPa) reinforced concrete or 130 ft (40 m) of moderately hard rock

The MOP is deployed from high altitude and allows gravity to add momentum to its 30,000 pound weight so that it hits with enormous kinetic energy.

Put simply, the MOP hits exactly where it is intended to hit with enough energy to bury itself 200+ feet into hardened concrete, then it explodes its 5,300 pound warhead.

The MOP is designed to be carried aboard B-2 and B-52 bombers so there's nowhere that is out of reach. The B-52 has a combat range of nearly 9000 miles, but aerial refueling means it effectively has an unlimited range.

During Operation Desert Strike on September 2/3, 1996, two B-52s flew out of Barksdale Air Force Base in Louisiana and disrupted communications in Baghdad with AGM-86C cruise missiles. By the time the mission was over, 34 hours had expired. Hence it would be fair to say that the B-52 is only limited in its range by the endurance of the four-person air crew.

The most likely aircraft to deliver the MOP however, is the B-2 Spirit which like the B-52, can carry two MOPs.

The largely composite B-2 has vastly reduced infrared, acoustic, electromagnetic, visual and radar signatures, extraordinary aerodynamic efficiency, a long range (6000 miles) without refueling and a massive payload. It is hence a potent delivery system for the likes of the MOP, as it is very difficult for defensive systems to detect, track and engage.

With aerial refueling, there is now nowhere to hide.