Sandia’s Robots Pull Apart Warheads to Recycle Thousands of Micro-grenades

More than 700,000 bomblets have been turned into recyclable metal thanks to hard-working robots

4 min read

Evan Ackerman is IEEE Spectrum’s robotics editor.

Sandia National Laboratories scientists built and programmed an automated robotic system to recycle weapons for the Army.
Photo: Regina Valenzuela/Sandia

The United States builds a lot of weapons. Unless a lot of really bad stuff happens all at once, we build more weapons than we can possibly use, and since we keep inventing new ones that are better and doing what weapons do, all the old stuff tends to just pile up. These piles of old explosives aren’t aging particularly well, leaving us with few options, which include forgetting about them for longer than is probably safe, or blowing them up. A third option is disassembly and recycling, but that’s dangerous for humans, because these weapons can be very old, and very lethal. Sandia National Laboratories has been helping the Department of Defense deal with some of its stockpile of M26 rockets, which are packed full of tiny little grenades and need to be taken apart very carefully.


M26 rockets are nasty things. They have an unguided range of 32 kilometers, making them less accurate than you should be comfortable with, but they make up for that with what’s inside their warheads. An M26 warhead contains 644 individual M77 micro-grenades (called bomblets), each about the size of a shot glass. The warhead detonates above the ground, dispersing the bomblets over an area of several hundred square meters. Each bomblet flutters to the ground on fabric drag ribbons and then detonates on impact with enough force to penetrate up to 4 inches of armor or likely injure or kill anyone standing within 4 meters. M26 rockets are typically fired in groups of at least six, which works out to 3,864 bomblets in total that cover about half a square kilometer.

I can’t find a good picture of the inside of one of these things, but I’m pretty sure that they look almost exactly like this:

The Rock

Anyway, the point of the M26 warhead is to be an effective tool of war, which is why it’s designed the way that it is. Unfortunately, there are a bunch of reasons why “cluster munitions” like these are a terrible idea, and the most significant one is that the M77 bomblets don’t always explode when they’re supposed to. Somewhere between 5 and 23 percent (depending on who you ask) of the M77 bomblets end up landing in trees or water or they bounce off of things or get tangled with each other on the way down or just don’t blow up because they’re duds. All of which means that wherever M26 warheads are used, you’ll find unexploded bomblets all over the place that can remain dangerous long after the conflict has ended and civilians have moved back into the area. (Efforts to ban cluster munitions have reduced their production and use, but such weapons still exist in large numbers.)

Militaries around the world know that this is a problem, but cluster munitions are depressingly effective, with a 2012 Pentagon test demonstrating that they’re nearly an order of magnitude cheaper to use and 40 times as fast to deploy than noncluster rockets. In 2008, the United States government promised to stop using cluster munitions by 2019 unless it could reduce the dud rate to under 1 percent. But now that it’s 2019, it turns out that the Pentagon didn’t manage to figure out how to do that, so it’s going to “set aside” the 2019 deadline and use cluster munitions whenever commanders feel that it’s necessary.

The last time the U.S. military used a substantial amount of cluster munitions was in 2003, but they’ve been around since the early 1990s. Some of these warheads are now 20 or 30 years old, and they’ve been replaced by newer versions that are both more accurate and more reliable. That leaves a whole bunch of warheads in need of careful decommissioning, full of hundreds of bomblets that were potentially unreliable even when they were brand-new, and I don’t know about you but I don’t want to be anywhere near that job.

Roboticists keep saying that robots are there for jobs that are dull, dirty, or dangerous. The best robots are busy doing at least two out of three of those things at once, and the disassembly and recycling of thousands of M26 rockets (about 700,000 bomblets) seems like it would definitely qualify as dull, and mostly likely also qualify as dangerous several times over.

In 2018, the DoD opened a Multiple Launch Rocket System Recycle Facility at the Anniston Munitions Center in Alabama, staffed with a team of nine robots integrated and programmed by Sandia National Labs.

Sandia bomb disassembly robotsThe Multiple Launch Rocket System Recycle Facility in Alabama uses robots to “demilitarize” warheads by cutting them into separate sections, removing foam packs filled with grenades, and detaching grenade fuses.Photo: Regina Valenzuela/Sandia

Sandia says that the robots are designed to “demilitarize up to 21 warheads per eight-hour shift,” which equates to 13,524 bomblets being recycled per day. The aluminum skin of the rockets is recyclable, as are the steel grenade bodies, and some of the copper bits inside the grenades themselves. 

The system is organized into nine “cells.” The first cell is the weapons disassembly system where warheads are cut into separate foam pack sections. The foam packs filled with grenades are then delivered to cells two and three where the grenades are removed from the foam packs. From there, individual grenades are delivered to cells four through nine where the fuses are detached. Once the fuses are detached, the munitions have been disarmed.

After this, the grenades and fuses are literally cooked to burn off the explosives inside of them. While the system is fully automated, it’s supervised by humans, and uses computer vision to detect anomalies like grenades that are stuck together and probably other things that are way scarier than that.

We’ve asked Sandia for pictures and video of this process, but there’s a limited amount that they’re able to share, and since it’s been very difficult to find any actual pictures of the inside of an M26 warhead, I’m guessing that’s because it’s classified or something. But it’s not that classified, since I did find an unclassified PowerPoint presentation with what appears to be some extra pictures of the system:

AMRDEC Missile Demil Integration EffortsImages: U.S. Army/AMRDEC

You can feel good about this system not just because of the robots, and not just because the robots are taking over dull and dangerous tasks from humans, and not just because they’re recycling deadly weapons—it’s also saving taxpayers millions of dollars over the life of the program. Thanks, robots!

[ Sandia ]

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