Mysterious Files PH

Although for many decades the planet Mars has been prodded, poked, driven upon, flown over and especially orbited by various spacecraft, landers and rovers sent over by a certain humanoid species on Earth, the two moons that orbit Mars have featured significantly more in science-fiction and video games than in scientific literature. This is now about to change when the Martian Moons eXploration (MMX) mission launches on October 19th, which will include a sample return from Phobos.

So far these two moons of Mars – Phobos and Deimos – have only received a few cursory glances by passing spacecraft, leaving many fundamental questions surrounding their formation and composition very much open. With the MMX mission this should change dramatically, with this spacecraft intended to perform detailed measurements of both moons.

In addition a rover – called Idefix – will perform a landing on Phobos for observations of its surface. This will be quite a feat as despite this lander coming in at 25 kg, on Phobos’ surface it will weigh only 15 grams due to the low gravity, or even less than the diminutive dog companion of Obelix, with potential bouncing as we have seen with previous landing attempts on such small bodies.

After launch, the MMX mission will take a year to arrive at Mars, in August of 2027, with Idefix being released in early 2029 for its hopefully soft paws-down on the surface of Phobos where it can scurry about for a while until the main MMX spacecraft lands later for its sample retrieval and return part of the mission. If everything goes well, this would mean that a sample of Phobos should be landing in Australia in 2031.

As electronic components grow ever smaller, a microscope has become an increasingly indispensable tool for any fine work; when inspecting electronics, though, especially solder joints, [Corebb] found a top-down view too limiting, so he built his own microscope with a rotating side-angle view.

The microscope itself is made of a commercial C-mount microscope lens assembly and a USB camera; the lens has a variable magnification factor up to 200x, which is plenty for electronics work, and is mounted on an adjustable stand to move the focal point. This is paired with an LED ring for illumination and two polarizing filters, one mounted on the lens and one one the lighting ring; when adjusted to 90 degrees from each other, these eliminate glare from reflective surfaces.

To view subjects from the side, [Corebb] built a snap-on adapter. This uses a pair of mirrors to capture a view from the side of the object and direct this through the main microscope lens. An additional concave lens compensates for the increased length of the optical path, and ball bearings let the whole adapter rotate around the microscope and capture the subject from any angle. [Corebb] tried 3D-printing the adapter, but found that flexing caused too much jitter; in addition to being sturdier, a machined aluminium part reduced shadows by allowing for thinner supports. The adapter snaps onto the microscope with small magnets, which keep the optical path consistently aligned.

This isn’t the first time we’ve seen a soldering microscope with a view from the side, but this does look much more affordable. If you’d like to try the polarized light source with your microscope, we’ve covered that before.

One of the often made claims about plastics is that they are chemically inert under most conditions, such as when exposed to water. This long-held belief has also challenged the notion that micro- and nanoplastics (MNPs) are dangerous to organisms such as us human animals. A hitherto unknown mechanism between common plastics as investigated by [Naixin Qian] et al. and published in Nature serves to generate highly reactive hydroxyl radicals when exposed to water.

Hydroxyl radicals (HO^•) are the neutral form of the hydroxide ion (OH^–). It’s a free radical that tends to be extremely short-lived due to its reactivity, much like the singular oxygen molecule that is freed at the plastic-water interface. The energy provided for this reactivity comes from the electrostatic effect, itself highly correlated with many plastics, with the six types of microplastics used in the experiment showing varying levels of free radicals, particularly for the more hydrophobic types.

This high reactivity of free radicals is a well-known problem in cellular biology, with evolution having developed many tools over the years to deal with capturing these radicals as well as repair the (DNA) damage that they can cause. The effect of these microplastics and their generated free radicals was thus studied as well.

Of note here is that the electrostatic effect itself already serves to draw charged biomolecules to it, before the impact of free radicals is considered. By using mouse red blood cells and exposing them to polystyrene (PS) microplastics fatal damage was observed to the red blood cells.

This indicates that there are at least three possible ways in which MNPs can be harmful to organisms. It also provides another clue to how this may affect the ageing of plastics, among other implications.

Currently there is still ongoing debate on whether MNPs are truly harmful and just how prevalent they may be in e.g. our bodies. Reliably detecting them in e.g. biological tissues remains a challenge, which this new study may also be helpful with, since one of our biggest blind spots is that we lack solid knowledge of how MNPs may behave inside an organism.

Classic DOS games never ran from within stand-up arcade cabinets in dollhouses, but [Juha Lilja] imagines a world in which they did. His Micro DOS arcade cabinet is described as a device that “runs nothing” because the tiny unit is actually streaming the games over Wi-Fi from a nearby PC. That doesn’t mean it’s just a glorified movie player, though — the cabinet is playable, if a bit awkward to do so.

The core of the micro arcade cabinet is a M5Stack AtomS3R running as an embedded remote terminal. One tilts the whole cabinet as if it were a virtual joystick to send up, down, left, and right. Button presses are done by pushing on the physical screen; it supports single, double, and long-clicks. While in theory one could install a micro joystick and buttons instead, [Juha] aimed to keep everything self-contained and use only what was already built into the AtomS3R. In this case, that’s a motion sensor and the single button which is activated by pressing the screen.

The games themselves run on a PC, with screen contents being streamed wirelessly to the little display and inputs being sent back. The firmware on the AtomS3R doesn’t know or care what game is being played; all it does is display what it’s told, and send back input events. The back end does the rest. This makes it pretty flexible, and a tiny arcade cabinet is a handy way to demonstrate the whole system. It’s a pretty slick addition to his daughter’s dollhouse, too.

If streaming DOS games (or whatever else) to economical endpoints is giving you some ideas, the GitHub repository holds code and a fuller explanation of how it works. There’s a deeper discussion on some of the finer technical points, as well. Watch it in action in the video embedded just below the page break.

Technically all that you need in order to make a drone fly is a single motor and single propeller, but realistically it becomes basically impossible to fly it at that point. In the case of helicopters you therefore need a second rotor somewhere to provide counterbalance to the first and to be able to steer.

There are of course a number of ways to make a drone fly with a single helicopter, but the compromise usually is to use very large propellers, as well as other mechanisms that make for a very large drone. This wasn’t good enough for [Joshua Bird] who wanted to have a very small, single propeller drone.

Key to making it work is not only a very high RPM, but also a hinged propeller hub that manipulates the  angle of the blades in such a way that both pitch and roll can be controlled if you react quickly enough. This turned out to be impossible using standard motor ESCs that do not directly measure the motor’s speed and position but rely on back EMF.

In the final prototype of the drone such details had to be measured directly, with super-fast adjustments to the motor’s speed only possible with custom controller code and a lot of trial and error. Even then the drone would often lose track of its position and crash once more. The solution there was to add an infrared beacon in the room and a sensor on the drone, to give it a fixed reference point.

You can find the project files so far on the GitHub project page, with upcoming changes to the drone design involving improvements like adding a scanner to the drone so that it can autonomously use features in its environment as fixed reference points. That way it might conceivably be able to fly outside as well, which would be quite exciting to see.

Modern computers are towers of glass and metal with very few large deviations from one to another. Monitor A will go against B, except you can’t tell them apart unless they’re on. At least, that is, compared to how different the old bulky monitors look compared to the new. [Andrzej Górski] seems to agree with this sentiment with his Oldputer, a blast from the past.

[Andrzej Górski]’s inspiration came from one component, and the main component of the project, an old e-ink display. When life gives you one of the slowest versions of a display, there really isn’t too much else to do other than pair it with slow old computers of the past. From that inspiration, there isn’t entirely a whole lot to do other than throw in an ESP32 and some LEDs for indicator lights. Put all this into a fun case, and you get one pretty desk ornament for whatever information you wanna display.

If you want to replicate the past again, you might want to look for the project GitHub here. If you’re looking for something even older, check out the replica of the MCM/70!

We aren’t sure what [Lazy_Duck] is doing with video games, but it must require a lot of controllers. Dismayed at the cost and complexity of commercial gamepads, they started soldering and 3D printing to get a cheaper basic controller.

The emphasis is on throwing things together, so there’s no dedicated PCB. Just a protoboard with an RP2040-Zero, a joystick, a few buttons, and a microswitch. A 3D-printed case rounds out the project.

On the printing side, the device uses heat-set threaded inserts, which should make for a very sturdy build. For software, the GP2040-CE firmware handles everything, acting like a controller and managing configuration via a web page.

Even if you don’t want a cheap gamepad, you could apply the principles and software used here to create any kind of gamepad you want. The firmware makes good use of the dual-core RP2040. It also offers a lot you could add to your version of the cheap controller, like OLED displays, RGB LEDs, and more.

Of course, you could also get fancy with the 3D printing side, too. For example, a resin printer makes nice button caps.