The GBU-43 Massive Ordnance Air Burst (also known as the Mother of All Bombs) that took out a lot of members of ISIS's Afghanistan franchise, is considered the largest conventional bomb in the American arsenal. Or is it?
There is another contender — the GBU-57 Massive Ordnance Penetrator.
So, yeah, there is another massive bomb. It is a heavier bomb — 30,000 pounds compared to the 21,700 of the GBU-43 MOAB. But the 30-foot long GBU-43 is ten feel longer than the GBU-57, and at 40 inches, it is about 8.5 inches wider.
The GBU-43 also has about 18,000 pounds of high explosive. According to a Defense Threat Reduction Agency fact sheet, the GBU-57 has about 5,300 pounds of high explosive.
So, what is the deal with the MOP? Why get it when you had MOAB? It's for the same reason you have a high-explosive round and an armor piercing round.
The MOAB, like the BLU-82 "Daisy Cutter," is like a giant high-explosive round. It detonates — either with the help of a standoff fuze or a proximity fuze — with the intent of using the blast to clear a large area or to leave a psychological mark on the bad guys.
The MOP, on the other hand, is like an armor-piercing shell. As its name suggests, it is designed to penetrate deep into a heavily-protected facility, then go boom. What sort of facility? Think bunkers and command posts.
The MOP, it should be noted, was also designed to fit inside a strategic bomber, notably the B-2A Spirit; but the B-52 Stratofortress (or BUFF) can also carry it.
Both bombs, by the way, use the Global Positioning System for guidance, allowing them to be dropped from high altitudes.
This not only allows the plane to escape the blast — something that was difficult with the unguided BLU-82 — but it also reduces the threat from air-defense systems. In the case of the MOP, altitude helps it go deeper underground, making sure that buried target you want to go away goes away.
(You can go ahead and make some penetrator jokes now.)