People go missing without a trace far more commonly than any of us would like to think about. Of course the authorities will conduct a search, but even assuming they have the equipment and personnel necessary, the odds are often stacked against them. A few weeks go by, then months, and eventually there’s yet another “cold case” on the books and a family is left desperate for closure.

But occasionally a small team or an individual, if determined enough, can solve such a case even when the authorities have failed. Some of these people, such as [Antti Suanto] and his brother, have even managed to close the books on multiple missing person cases. In an incredibly engrossing series of blog posts, [Antti] describes how he hacked together a pair of remotely operated vehicles to help search for and ultimately identify sunken cars.

The first he built was intended to perform reconnaissance using a consumer side-scan sonar unit. While these devices are designed to be mounted to a “real” boat, [Antti] didn’t have the room at home for one. So he did some research and eventually settled on an affordable solution that combined a watertight plastic box with pontoons made out of PVC pipes. We’ve seen similar designs before, and have always been impressed with the stability and payload capacity offered by such an arrangement given its low cost and ease of assembly.

In an interesting twist [Antti] decided to outfit his craft with quadcopter motors and propellers to create a sort of airboat, which would keep it from getting tangled up in weeds. We also appreciate the no-nonsense method of viewing the sonar’s output remotely — all they had to do was take an old smartphone, point its camera at the unit, and open up a video calling application.

While having the sonar data would help the brothers identify potential targets on the bottom, it wasn’t enough to make a positive identification. For that, they’d have to go down there and directly image the object being investigated. So the second project was a remotely operated vehicle (ROV). Its PVC frame might look a bit low-tech, but [Antiii] designed the central “dry hull” to survive at depths of up to 100 meters (328 feet). With cameras, lights, a Raspberry Pi, and an Arduino Mega pulling it all together, the finished product is a formidable underwater explorer.

Combined with diligent research on the individuals who went missing and the areas in which they were last seen, the brothers were able to use these vehicles to solve a pair of missing persons cases that had been open for more than a decade. Their work earned them the personal thanks of the President of Finland, and a medal that’s generally only given to police officers.

Our hats off to this intrepid duo — surely there’s no more noble a pursuit than dedicating your skills and free time to help others.

So you say you missed the Great Solar Storm of 2024 along with its attendant aurora? We feel you on that; the light pollution here was too much for decent viewing, and it had been too long a day to make a drive into the deep dark of the countryside survivable. But fear not — the sunspot that raised all the ruckus back at the beginning of May has survived the trip across the far side of the sun and will reappear in early June, mostly intact and ready for business. At least sunspot AR3664 seems like it’s still a force to be reckoned with, having cooked off an X-class flare last Tuesday just as it was coming around from the other side of the Sun. Whether 3664 will be able to stir up another G5 geomagnetic storm remains to be seen, but since it fired off an X-12 flare while it was around the backside, you never know. Your best bet to stay informed in these trying times is the indispensable Dr. Tamitha Skov.

Back here on our soon-to-be-incinerated planet, you know we’ve reached the peak of the AI hype curve when you see something like AI competitive thermal paste being hawked. That’s the marketing niche Cooler Master has staked out for its new Cyrofuze 5 thermal paste, which is supposed to somehow make your computer smarter by keeping it cooler? Or maybe not; it’s not really clear from Cooler Master’s Chinese website for the product what the AI advantages are, and sadly the Cryofuze 5 line doesn’t seem to be offered on the US site. Which is a shame, because the new smartening goo comes in six designer colors that for all the world look like a Bob Ross palette — it that alizarin crimson and phthalo blue? Who in their right mind wouldn’t want a chance to color coordinate their thermal grease while simultaneously making their machine more AI competitive?

Speaking of AI, we’ve covered a lot of interactions between humans and autonomous vehicles in this column, with most of them tending toward the violent. But we’ve finally got a more heartwarming interaction to report, where a pedestrian helped a stuck delivery vehicle out of a tough spot. The truck, which is really only a little bigger than those munchie-delivering robots that ply college campuses, maneuvered itself onto a driveway sporting a pair of speed bumps spaced almost exactly as far apart as the vehicle’s wheelbase. The front wheels made it over the first bump, but when it came time to climb both obstacles at the same time, the poor little truck just couldn’t manage it. The fact that the bumps were a significant fraction of the wheel diameter on the tiny truck likely didn’t help, but thankfully a pedestrian took pity and gave the little fella a push. The bot’s rear wheels seemed to be having trouble clearing the last bump, too; the video cuts off too soon to tell, but we’ll give it the benefit of the doubt.

Victim blame is generally in bad form, but if you don’t even bother to change the default password, can you really call a cyberattack a “break-in”? That’s the question we have after learning of an alarming increase in cyberattacks against public infrastructure in the US, including public water supplies in Pennsylvania and Texas. While the separate attacks resulted in no damage to the physical plants, the article links to a report listing some attacks that did result in damage, including an intentional release of 800,000 liters of sewage in Australia in 2000.

And finally, speaking of cybersecurity, if you’ve ever procrastinated on keeping your OS patched, what happened when a Windows XP machine was put online with no protection should spur you into action. YouTuber Eric Parker put an XP machine on the raw internet — no router, no firewall, and no anti-malware software. It only took about ten minutes for the first signs of infection to appear, and things went downhill pretty fast from there. Parker notes that the same setup on a Windows 7 machine resulted in no major malware infections after several hours, which should be a gut punch to those who fought so long against updating from XP.

NASA astronaut [Don Pettit] shared a short video from an experiment he performed on the ISS back in 2012, demonstrating the effects of sound waves on water in space. Specifically, seeing what happens when a sphere of water surrounding an air bubble perched on a speaker cone is subjected to a variety of acoustic waves.

The result is visually striking patterns across different parts of the globe depending on what kind of sound waves were created. It’s a neat visual effect, and there’s more where that came from.

[Don] experimented with music as well as plain tones, and found that cello music had a particularly interesting effect on the setup. Little drops of water would break off from inside the sphere and start moving around the inside of the air bubble when cello music was played. You can see this in action as part of episode 160 from SmarterEveryDay (cued up to 7:51) which itself is about exploring the phenomenon of how water droplets can appear to act in an almost hydrophobic way.

This isn’t the first time water and sound collide in visually surprising ways. For example, check out the borderline optical illusion that comes from pouring water past a subwoofer emitting 24 Hz while the camera captures video at 24 frames per second.