Reading Isn’t Rocket Science… But In This Case…

August 20, 2026 by Al Williams 1 Comment

While Hackaday’s bread and butter is, of course, hacks, we sometimes cover things that most of us are interested in that are probably out of reach for the typical hacker. Space, for example, is undeniably cool, even though your chances of putting yourself or even your own rover on the Moon aren’t very good at the moment (but, of course, give it time). If you are looking for something to put on your e-reader and you are also interested in space, save your money and get some downloadable books directly from NASA.

There’s something for everyone on the site. The site has four main categories: aeronautics, Hubble, science, and NASA history. Aeronautics has two volumes of “NASA’s Contributions to Aeronautics,” a book on the X-15, and a book about aviation pressure suits. Want to know more about the giant wind tunnel at Langley?

For the Hubble, you’ll find titles that have great images, of course, but also a book with an overview of the telescope or, if you prefer, about gravitational lensing.

The science titles go really deep with books on black holes, Landsat, the Cassini mission, and the Spitzer telescope. If you prefer history, there’s everything from a history of near-Earth object research to lessons from the Columbia tragedy for engineers, managers, and leaders. We were also interested in the book “Archaeology, Anthropology, and Interstellar Communication.”

The books are typically available in EPUB or PDF, and they are all free. Just what you need for your next plane trip or to round out your Calibre library.

We do love free books, we just can’t get enough.

NASA Tests Featherweight Radar Antenna For SkyFall Mars Helicopters

August 19, 2026 by Maya Posch 4 Comments

After the little Mars helicopter Ingenuity blew everyone away with its performance, it was clear that a future Mars mission should involve more helicopters like it, with even more capabilities. The main proposal here is NASA’s SkyFall mission which would involve three autonomous helicopters, capable of searching for resources like water. To this end they would need a ground-penetrating radar system, with the antenna somehow folding away for landings, an idea that JPL is currently testing.

The SkyFall mission is currently penciled in to commence in 2028, following which it will be deployed from the Space Reactor-1 fission reactor-powered spacecraft based around elements of the now discarded Lunar Gateway space station. This obviously poses some uncertainties around when and if this mission will actually take place, but that doesn’t prevent JPL engineers from solving issues with these SkyFall helicopters.

As the antenna for the ground-penetrating radar extends beyond the landing legs, it was crucial that said antenna was flexible enough to simply fold in on itself like fabric. For this they used an existing flexible antenna design called Vivaldi, which was downscaled for the helicopters and subsequently tested to see how many simulated Mars landings it would be able to resist, as well as the effect of the cold nights and warm days.

We’re looking forward to seeing these SkyFall helicopters zip over the Martian surface. Maybe they can even swing by Ingenuity while they’re in the neighborhood.

An arm and a hand: on the arm is a chunky blue box, and in the hand is a phone showing a dashboard.

HYDR8 Will Lead You To Water, But Will You Drink?

August 19, 2026 by Kristina Panos 7 Comments

[Ayushmaan] states up front that most of his free time is spent “building things that probably didn’t need to exist”. Well, this one might be an anomaly, because it seems pretty useful to us.

HYDR8, as it says on the tin, is a wearable that knows when it’s time to hydrate. The impetus for this one was something we all chase: the flow state. [Ayushmaan] would sit down, get deep into work, and look up hours later to to find that he had a headache and a full water bottle. Phone reminders were soon swiped away in annoyance.

This wearable is based on a XIAO ESP32-C3. It reads heart rate, oxygenation, skin temperature, and both the ambient temperature and humidity. It also learns your personal resting numbers range.

Taking all of this into consideration, it generates a heat/hydration stress score between 0-100. The thing is, HYDR8 tells you specifically what to do; sometimes it’s ‘drink water’ and other times, it’s ‘find shade’.

The wearable itself, while somewhat chunky, is pretty simple: it only shows the time and a message when it matters. The ESP32 hosts a full dashboard on your phone.

Keep in mind that this is not a medical device, it’s an experiment, a prototype. It can’t measure how hydrated you are. Instead, it measure hydration stress.

If you don’t want to wear anything, here’s a smart straw that uses a tiny turbine flowmeter and a Hall effect sensor to record the volume sipped, and detect whether the sipper is low on fluids. And if you find yourself under the hot lights of a wet bulb event, here’s how to survive it.

Mini Blinking Barrels Keep Desktop Traffic In Check

August 19, 2026 by Tom Nardi 6 Comments

Your desk or bench is a work area, so why not make it look the part? That’s the idea behind the miniature blinking traffic barrels that [Glen Akins] recently put together. Of course, just a single blinking light doesn’t really sell the idea of a busy construction zone, so he spent a somewhat surprising amount of time and effort optimizing the design for small-scale production.

The end result is a fascinating write-up that dives into the design decisions [Glen] made. Every aspect of this project, from the overhang of the “handle” on the 3D printed barrel to the number of passive components on the PCB was carefully considered. Critics may say [Glen] put too much thought into something that didn’t need to be so complex, but projects like these are an excellent way to keep your skills sharp — there’s no such thing as practicing too much.

Starting with the design of the barrel itself, we appreciate that [Glen] kept the capabilities of his desktop 3D printer in mind. By breaking the design up into multiple pieces and avoiding overly steep angles, he produced a design that prints cleanly without the need for support material. His step-by-step documentation and screenshots also serve as a great introduction to designing parts in Fusion if that’s something you’re interested in.

From there, things switch over to the electronics. Some in the audience will bemoan that he’s using a PIC12F1612 microcontroller to blink a single LED instead of a 555, but [Glen] brought the receipts on this one. Not only does the PIC offer more flexibility in terms of getting the blinking to look the way he wants, but it requires fewer passive components on the board and is considerably more energy efficient than the iconic timer IC. Even if you ignore all the other advantages, he calculates that going with a 555 would have cut the battery life of the finished product by approximately 15%.

This is one of those projects that’s difficult to summarize in such a terse format, as every time you think the write-up must be about over it takes a new turn on you. We were mildly bemused when the second iteration of the PCB popped up, but by the time he introduced the custom programming adapter board, we knew [Glen] wasn’t messing around.

Unsurprisingly, this isn’t the first time we’ve seen [Glen]’s handiwork. You may recall seeing his RP2040-powered sound board earlier this year, but his name has been popping up on these pages for more than a decade now.

Historical Hack: Henri Griffard’s Steam Injectors

August 19, 2026 by Tyler August 9 Comments

Here’s a historical hack for you: you have a big, rolling pressurized kettle, also known as a steam locomotive. It needs water to make up for the steam constantly chuff-chuff-chuffing away, or bad things happen. How do you get water from an unpressurized tender into a high pressure boiler with no moving parts? What you need is a some way to inject steam with no moving parts — a steam injector, if you will. [Marc Flint] found that the steam injectors were the hardest part of a loco to understand, so he made a video for all of us once he’d figured it out.

The steam injector isn’t a new idea. [Henri Griffard] came up with it back in the 1850s to replace expensive and maintenance-hungry pumps. It’s rather ingenious and uses the fluid mechanics uncovered by another European bloke by the name of Bernoulli. First, the high-pressure steam from the boiler goes through a converging-diverging nozzle to drop its pressure and speed its flow up, just as you’d guess if you’ve seen Bernoulli’s laws. Even more vacuum-inducing is the presence of water: the steam, already cooled by its expansion, hits the water in the pipe open to the tender, and condenses into it, shrinking a couple of orders of magnitude, creating a vacuum that draws in no small quantity of feed water. That one we did not expect from Bernoulli, but it makes sense. So how to get from below atmospheric pressure to the 180-odd PSI or more in the boiler?

Well, the water is now moving at a good clip, between the Venturi effect and the momentum gained from absorbing that steam, so another converging nozzle is the trick. Bernoulli’s law, once more! A one-way valve lets the now-pressurized water into the boiler, with a gap in between to dump water while the pressure builds up. It’s a clever trick, and since the steam coming from the boiler makes it back inside along with at least some of its heat energy, it’s much more efficient in both coal and water than running a pump. It’s also a bit of a head scratcher how it works unless someone sits you down to explain it, so we’re glad [Marc] did.

Not many of us are likely to use this knowledge directly — unless we’re firing up a 90 year old boiler or building a new steam locomotive — but seeing how great engineers of years past made use of basic physical laws can serve both as education and inspiration.

Continue reading “Historical Hack: Henri Griffard’s Steam Injectors” →

Smarting Up A Doorbell With Zigbee

August 19, 2026 by Zoe Skyforest 11 Comments

Once upon a time a doorbell was little more than a button, a transformer, and a bell tucked somewhere around the house. These days, they get a little bit fancier. [Philipp Schweizer] has recently been exploring how to turn existing dumb doorbells into smarter ones.

The build is based around a wired doorbell setup, in particular, a Vistadoor ADV-100. [Philipp] was able to find a simple place to tap in to a signal that went to 5 V when the doorbell was rung. He wanted to hook this into his smart home system as easily as possible. Thus, he grabbed a rather unique part—the ESP32-H2. This is notable in the ESP32 family for having no WiFi connectivity. What it does have, however, is an 802.15.4 radio good for Thread and Zigbee communications.

[Phillip] explains that hooking the ESP32-H2 up to fire a notification to Home Assistant every time the doorbell goes off is easy—and it doesn’t mess with the standard doorbell’s chiming behavior one bit. He also explains how to set up neat automations, such as having a separate smart camera capture an image when the door bell is fired.

If you’re looking to integrate an existing doorbell into your Home Assistant setup, this project could be just what you need. We’ve featured some other neat doorbell builds too, like this touchless design from the dark days of the coronavirus pandemic.