GBU-57 Massive Ordnance Penetrator Successor In The Works

[rangerrebew]

GBU-57 Massive Ordnance Penetrator Successor In The Works
Here's what we know about the new weapon being sought to replace the B-2's MOP and equip the B-21 in the future.
Joseph Trevithick

Published Jun 24, 2025 2:12 PM EDT

The U.S. Air Force's first combat employment of 30,000-pound GBU-57/B Massive Ordnance Penetrator (MOP) bunker buster bombs in recent strikes on Iranian nuclear sites draws new attention to work toward a successor.
 

The U.S. Air Force’s first combat employment of 30,000-pound GBU-57/B Massive Ordnance Penetrator (MOP) bunker buster bombs in recent strikes on Iranian nuclear sites draws new attention to work toward a successor. There was already very active U.S. military interest in a new Next Generation Penetrator (NGP) when the MOP first began entering service in the early 2010s.

B-2 Spirit stealth bombers dropped 14 GBU-57/B on targets in Iran – 12 on the enrichment facility at Fordow and two more on the one at Natanz – during strikes this past weekend dubbed Operation Midnight Hammer, which you can read more about here. The B-2 is the only aircraft cleared to employ the MOP operationally, but the forthcoming B-21 Raider stealth bomber is expected to be able to employ them, as well. B-52 bombers have also dropped the huge bunker busters during testing. The existing MOP stockpile is understood to be relatively small, but Bloomberg reported last year that work was being done to help triple or even quadruple the annual production capacity of the munitions.

The 20-and-a-half-feet-long GBU-57/B is a precision-guided bomb that consists of a penetrating “warhead,” which has its own designation (BLU-127/B), along with a GPS-assisted inertial navigation system (INS) guidance package, specialized fuzes, and other components. The explosive content of the MOP, which also has a diameter of 31-and-a-half-inches, is only roughly 20 percent of its total weight.

https://www.twz.com/air/gbu-57-massive-ordnance-penetrator-successor-in-the-works

[rangerrebew]

The old one seems to have worked quite well in Iran.  But I'm pleased the military is researching bigger, more destructive bunker busters,

[BobfromWB]

Excerpt:

"The most recent publicly stated requirements for the NGP come from a contracting notice the Air Force put out in February 2024. It called for a warhead weighing 22,000 pounds or less, and that would be “capable of blast / frag[mentation] / and penetration effects,” but did not specify a desired gross weight for the entire munition. No prospective dimensions were provided, either.

“The prototype penetrator warhead design effort should allow integration of technologies acquired and lessons learned under previous penetrator warhead developments to meet performance requirements for the HDBT target set,” the contracting notice added. “The USAF will consider novel, demonstrated, or fielded Guidance, Navigation & Control (GNC) technologies with viability for integration into a warhead guidance system design that can achieve repeatable, high accuracy performance in GPS aided, degraded, and/or denied environments.”

"The notice also said that a “terminal accuracy” of “CE90 w/in 2.2m both in GPS aided, degraded, and denied environments” was desired. What “CE90 w/in 2.2m” means in layman’s terms is a munition that can hit within 7.2 feet (2.2 meters) of a specified impact point at least 90 percent of the time."

[Smokin Joe]

Excerpt:

"The most recent publicly stated requirements for the NGP come from a contracting notice the Air Force put out in February 2024. It called for a warhead weighing 22,000 pounds or less, and that would be “capable of blast / frag[mentation] / and penetration effects,” but did not specify a desired gross weight for the entire munition. No prospective dimensions were provided, either.

“The prototype penetrator warhead design effort should allow integration of technologies acquired and lessons learned under previous penetrator warhead developments to meet performance requirements for the HDBT target set,” the contracting notice added. “The USAF will consider novel, demonstrated, or fielded Guidance, Navigation & Control (GNC) technologies with viability for integration into a warhead guidance system design that can achieve repeatable, high accuracy performance in GPS aided, degraded, and/or denied environments.”

"The notice also said that a “terminal accuracy” of “CE90 w/in 2.2m both in GPS aided, degraded, and denied environments” was desired. What “CE90 w/in 2.2m” means in layman’s terms is a munition that can hit within 7.2 feet (2.2 meters) of a specified impact point at least 90 percent of the time."

From the satellite images, those were some pretty impressive groups at Fordow,  from 30,000 ft.

Consider, if that grouping is 100 yards across, the MOA of that impact group is just over 0.57.
That's impressive enough for most high quality rifles.

[Fishrrman]

We already have such weapons, and have had them for many years.

They're called small tactical nukes, and can be dialed in for relatively low yields.

I wouldn't be surprised if they had some that kept radiation to a minimum, as well.

What we don't have is the will to use them.

[Smokin Joe]

We already have such weapons, and have had them for many years.

They're called small tactical nukes, and can be dialed in for relatively low yields.

I wouldn't be surprised if they had some that kept radiation to a minimum, as well.

What we don't have is the will to use them.

No one wants to take a chance on getting caught...
That might open a whole 'nother kettle of worms.