This is literally a robotic intestine puking rocket fuel. It’s being developed in Japan, by roboticists from Chuo University and JAXA, the Japan Aerospace Exploration Agency.
You’ll be relieved to learn that it’s a robotic intestine puking rocket fuel with a purpose: It’s designed to replicate the peristaltic motion of a real intestine in order to gently mix ingredients to make solid rocket fuel. The researchers say their machine is safer than conventional mixers because the fuel doesn’t experience high shear stress inside the undulating rubber tubing and is never in contact with metal, avoiding the risk of fire and explosions.
The idea is to turn the solid rocket fuel manufacturing process into a continuous operation rather than a discrete one, replacing rocket fuel mixing bowls that give you fuel in batches with a system that can just continuously pump out fuel instead. It’ll be more efficient, safer, and easier to scale, helping keep solid fuel rockets competitive for small satellite launches.
And that means a robotic intestine puking rocket fuel.
The stuff coming out of the machine represents a rubbery mixture of ammonium perchlorate powder (an oxidizer), aluminum powder (a high energy fuel), and an elastomer binder consisting of hydroxyl-terminated polybutadiene (HTPB). Generally, mixing these things together is done in what look like industrial bread dough mixers, which allows each batch to be carefully controlled to make sure the fuel comes out just right. Also, when you’re mixing up something designed to be more or less as explosive as possible, you want to do it very, very gently.
A peristaltic pumping system is able to mix ingredients both safely and effectively. It works just like your intestine does, with rhythmic contractions moving stuff along a tube, except unlike your intestine, the system is closed at both ends and the stuff is added in the middle, along with pressurized air. As the sections of the tube expand and contract, everything inside gets mixed together. An operational system would likely consist of a long mixing loop that would continuously ingest raw rocket fuel ingredients at one end, and then, er, expel them all mixed together at the other.
Once the fuel has been mixed, it’s poured into whatever shape you need it to take (lots of interesting options here) and cured into a rubbery solid. While the stuff in the video (which was associated with a media event, it looks like) is simulated propellant for safety reasons, this system has successfully mixed real propellant as well, which the researchers fired off in a benchtop rocket test just to make sure that it worked (it did).
There’s more detail in the Robostart article, by Kazumichi Moriyama, below, once you’ve translated it from Japanese, and I was also able to find a 2016 paper by some of the same researchers. If you’d just like to learn more about solid rocket fuel in general, here’s a video from the 1960s showing Thiokol’s fuel manufacturing process. And if you want something a bit more up to date (if less focused), this NASA video shows the steps involved in manufacturing one of the solid rocket boosters for the Space Launch System.
Evan Ackerman is a senior editor at IEEE Spectrum. Since 2007, he has written over 6,000 articles on robotics and technology. He has a degree in Martian geology and is excellent at playing bagpipes.