A test setup for an actuator is shown on a benchtop. A power supply connects to a cylindrical actuator, which has an arm pressing against a load cell. The load cell's output is shown on a computer screen, which is labelled "Torque".

Building An Actuator For A Walking Robot

August 16, 2026 by 2 Comments

Unlike biological systems, which can use muscles, robots that try to imitate them don’t have particularly fast, powerful, compact linear actuators available. This puts walking robots at a particular disadvantage, since they can’t spread their actuators along a limb and have to place them right at the joint. [Food for Robots] took on the challenge of building such a joint-mounted actuator, and shared the results in a recent video.

[Food for Robots] is building a walking robot, so he needed a compact, lightweight, and backdrivable actuator capable of producing 20 Newton-meters of torque. He’d previously built a largely 3D-printed actuator, but when he tried to exceed 10 Nm of torque with it, various parts kept breaking. He therefore machined the second iteration out of aluminum; since it didn’t need to be 3D printed, he switched from a Capstan drive to a planetary gearbox. The gearbox sits in the center of the actuator, inside the stator, and uses several stacked layers of gears to increase strength within the limits of a small CNC.

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R-Selecting Tiny Probes To Shotgun Into Saturn’s Rings

August 16, 2026 by 33 Comments

In ecology, there used to be a concept — now largely unfashionable — that species could be described as r- or K-selected, depending on how they treat their offspring. An elephant that has one calf every few years and devotes immense resources to them is adopting a K-selection strategy — much as NASA traditionally has to its flagship probes, like Cassini. A sea turtle who leaves hundreds of eggs in a clutch on the beach and leaves without saying “good luck”, content in the knowledge that one of them will probably make it to adulthood is engaging in an r-selected strategy, and it’s this strategy that [Dr. Michael Rubenstein] is proposing for a next-generation mission to Saturn as part of NASA’s Innovative Advanced Concepts Program for 2026. Entitled “Actively Steerable Femtosat Constellations for In-situ Exploration of Saturn’s Rings, Atmosphere, and Magnetosphere”

The concept is pretty simple: the rings are a horrifying mess of dust, debris, and ice bits of all sizes that represent almost certain death for a spacecraft. By launching 10,000 femtosatellites, those odds of almost certain death become an almost certainty that one or more will make it through with precious data. In the immortal words of Lord Farquhar, “Some of you may die, but that is a sacrifice I am willing to make.” With Cassini, NASA would never consider such a sacrifice. With itty-bity femtosatellites, it starts to make sense. We’ve been saying for years that the future of space is tiny, but these sacrificial probes would make even modern cubesats and picosatellites look big.

Thanks to [Richard HT] for the tip! His tip was to a podcast featuring [Dr. Rubenstein] with [Fraser Cain], which we’ve embedded below. It has a lot more details than NASA’s official blurb page.

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Researchers Hack An Airline Analog

August 16, 2026 by 24 Comments

Modern airliners are rather complicated feats of engineering. Innumerable safety-critical components are connected with tens of miles of wiring, complex digital buses, and dozens (perhaps hundreds) of computers. But, as hackers, we know that any computer can be hacked and, of course, aircraft avionics are no different. 

Modern aircraft typically use the ARINC 429 protocol. This differs from many protocols we see where multiple transmitters are allowed. ARINC 429 has a single transmission source. This makes a transmission-override attack hypothetically difficult, as an attacker was thought to need to physically replace a legitimate transmitter (like a flight management computer), a rather daunting task. However, the ARINC 429 transmitters sit behind a pair of 37.5 ohm resistors, so by transmitting on the same line, an attack device can simply override the legitimate transmitter’s power.

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Machine Learning COFFIES “Hears” Sunspots Before We Can See Them

August 15, 2026 by 12 Comments

In this age of neural net “AI”, even the most skeptical of Butlerians have to agree that these machine learning models can be very, very good at pattern recognition if nothing else. NASA is on the same page, and to take advantage of that pattern recognition, they’ve built a machine learning module called COFFIES, which stands for Consequence Of Fields and Flows in the Interior and Exterior of the Sun, because at NASA everything is an acronym, or at least a backronym. Like most such names, this one is at least vaguely descriptive: the model is trying to predict what’s going on in the material flows and magnetic fields deep within our local star, and using those inferences is able to predict active regions– that’s sunspots to us chickens — up to 12 hours before they visibly form.

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Turning Energy Drinks Into Rocket Fuel

August 15, 2026 by 13 Comments

Sometimes claimed to give you wings, energy drinks can, at the very least, be used to make rockets fly. This is what [Nate Scovill] did in a recent video, where cans of the sugary stuff are processed to give a rocket its proverbial wings.

The basic concept is so-called rocket candy, which uses the fact that sugar is a pretty decent fuel type that — when combined with an oxidizer like potassium nitrate — can be turned into solid rocket fuel. Naturally it’d be easiest to start off with a pure source of sucrose or sorbitol for the sugar, but what if you only have access to cans of sugary soda?

Removing the moisture from the energy drink was the obvious first step, as water and rocket fuel aren’t a great mix. Adding and mixing potassium nitrate to the resulting thick syrup created the fuel-oxidizer mixture, also known as rocket fuel. This did take a detour involving removing the carbonation using a vacuum chamber, as CO2 and fire do not really like each other either.

We previously covered making your own rocket candy, though it’s far from the only rocket fuel that can be made at home using products bought at the local supermarket. Obviously, doing so comes with a whole heap of risks, not least of which is the notion that the difference between a rocket and a bomb is a pretty thin and fuzzy line that you do not want to accidentally cross.

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Peeling Fruit With The Power Of Steam

August 15, 2026 by 9 Comments

Steam power is a staple of the steampunk aesthetic, thermodynamics, and a checkpoint for the budding mechanical engineer studying heat cycles. But because food is largely made of water, steam is also common in the culinary arts. So it’s no surprise that when thermodynamics is applied to cooking, exciting things can happen. 

This particular example of steam-powered culinary happenings is inspired by industrial potato-peeling machines. By adding high-pressure, high-temperature steam to a pressure vessel with potatoes inside, heat can transfer more easily to the inside of the potatoes. Because the pressure is so high, however, the water in the skin won’t boil. This is fundamentally the same concept as a pressure cooker. However, what’s different is that instead of a pressure cooker’s slow release, these industrial peeling machines rely on explosive decompression, flash boiling the water underneath the potato’s skin. This rapidly expanding steam rips away the skin in a nice clean sheet.

But, to [Stuff Made Here’s] disappointment, there were no videos of the process on the internet. But, fortunately for us, being an engineer of complicated machines means that there is one now that you can watch below.

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Scanning For Lifesigns With ESP32 And Raspberry Pi

August 15, 2026 by 28 Comments

It’s a sci-fi trope that you can ‘scan for life signs’ and detect if there are humans — or suspiciously human-shaped aliens — present, but in real life it’s harder than that. [The Masked Bear]’s wifisense-pi project isn’t really scanning for signs of life, either, unless you happen to consider breathing a sign of life. Even then, it’s not detecting breathing per se, but the subtle motion that goes with it: it’s a very sensitive motion detector that relies on the fact that we fleshy bags of goo disturb WiFi signals with our presence, and motion alters those disturbances.

We’d probably waste a lot of time watching the signal graphs on the WifiSense-Pi dashboard.

The device uses an ESP32-S3 to measure the radio channel 100 times per second, while a Raspberry Pi 4 provides the signal processing muscle. It can detect the slightest motions, and even determine the presence of a perfectly still human by their breathing, though you can hide your presence for as long as you can hold your breath. A single sensor, no matter how sensitive, cannot give position information, and while multiple humans will distort WiFi more than a single one, [The Masked Bear] reports you cannot reliably extract that signal. So this project answers the question: “are there humans in this room?” Or, even more likely, “are there any large breathing animals in this room?” We can’t imagine a 50 kg Mastiff looking any different to this sensor than an equivalent mass of quivering human flesh.

Before you dismiss this as just another motion sensor, keep in mind that it is sniffing the signals already present on the 2.4 GHz band, and, like the WiFi signals themselves, it can work through walls. So we think it’s pretty nifty. Of course, there are many other ways to detect humans, from machine-learning cameras to millimeter-wave sensors to a simple PIR. This isn’t the first project we’ve seen that uses WiFi like this. It isn’t even the first with an ESP32, but it’s an interesting implementation worth checking out.