What do the Houthis and Mad Max have in common? They share an amazing tenacity when it comes to being scrappy with their supplies. For example, this Houthi technical isn’t exactly Mad Max canon, but still embodies the spirit of the DIY universe.
Here we have a Soviet R-60 missile that was sent to South Yemen around 1979 as part of an Su-22 and MiG-21 package which was inherited by the Yemeni government following the reunification in the 1990’s. These were then inherited by the Houthis, now serving as Surface-to-Air missiles. This picture is from around 2018, and shows the beginning of the Houthi AAM-SAM conversion projects. It is reported that the South Yemen government, the only communist government in the Arab world at the time, received up to 100 of these missiles, and not even the good stuff! The R-60M, a much-improved version of the R-60 with a nitrogen-cooled seeker, was still in development by the time the South Yemeni government had procured these missiles.
Fast forward a few years, and in 2020 the Houthis unveil what they are calling ‘domestically produced’ surface-to-air missiles that look a lot like some other Russian missile systems. Specifically, we see an R-73 rebranded as the Thaquib-1.
R-73 display piece for comparison
As part of that video, there are additional shots of their R-27 and R-77 (Thaquib-2 and Thaquib-3, respectively) conversions as well, but we are less interested in those two as their guidance systems differ from the R-73. Russian R-27 and R-77 missiles are either active or semi-active radar homing missiles, which do not require liquid nitrogen cooling of a sensor to bolster their accuracy.
Cryogenic cooling is used in infrared missile systems to increase the sensitivity of the infrared seeker and is a critical piece of the accuracy component. Infrared sensors are often called ‘heat-seaking’ sensors, as very hot objects tend to radiate a lot of infrared radiation. Cooling the sensor on infrared missiles decreases background noise, thus making the sensor more sensitive to the non-burning parts of an aircraft (sides, front). Normally, these R-73 missiles, being air-to-air missiles, are attached to a hardpoint. In this case, the APU-73 missile pylon or hardpoint is what attaches to the aircraft that is carrying it. This hardpoint is not just a hunk of metal, but a rather sophisticated electrical and mechanical system that is responsible for many tasks of the pre-launch missile lifecycle. Part of its mission is to provide liquid nitrogen to the missile for its IR seeker, providing that cryogenic cooling.
Curiously enough, at the unveiling we see the Houthi missile without its pylon. Now, it could be nothing – the Houthi’s could have come up with another way to provide liquid nitrogen to the missile or they could have simply not included the APU-73 in the display. There are numerous different explanations as to what is going on regarding the missile and its launch apparatus, but none of this changes the fact that the Houthis need liquid nitrogen for this missile to work properly.
The production of liquid nitrogen is a fairly sophisticated process involving separating water, carbon dioxide, and oxygen from atmospheric air with a compressor, semi-permeable membrane, and lots and lots of energy, time, and effort. Time and manpower might be on the side of the Houthis, but getting sophisticated components to make liquid nitrogen is a big challenge for the Houthis at this point in time.
So what does this mean? Well, a few implications can be garnered from these realities. First, we should be on the lookout for liquid nitrogen being smuggled into Yemen. This would be the easiest and most readily-usable product to get these missiles up and running (or keep them up and running). Second, importing other precursor tools and systems that could lead to the indigenous production of liquid nitrogen would be something we should be able to see in the smuggling interceptions of goods headed to the Houthis – helium air compressors, zeolite filters for the gaseous separation, cryo-cooler systems, etc. See the linked Veritasium video below for a good explanation of the liquid nitrogen distillation process! Third, they could just try to use the R-73 systems without the liquid nitrogen cooling, but that would likely be a huge waste of a weapon system that they probably aren’t going to get their hands on any time soon.
Although the Houthis claim they have their own indigenously produced SAM in their Mira/Maraj, this missile is essentially a solid propellant-filled pipe with Iranian servos and guidance slapped into it – nowhere near as sophisticated or effective as these Russian systems. Over a third of the Russian Air-to-Air missile systems inherited by the Houthis were these R-73 missiles according to CIPRI arms sales data. If over a third of the Houthis most advanced air defense systems were greatly hindered, their ability to threaten US Reaper drones and other coalition air force equipment would be significantly impacted.
- “Making Liquid Nitrogen From Scratch!” – Veritasium, https://www.youtube.com/watch?v=dCXkaQa53QQ
- “Houthis Unveil Russian Air-to-Air Missiles as SAMs” https://www.janes.com/osint-insights/defence-news/houthis-unveil-russian-air-to-air-missiles-as-sams
