Say what you will about [Thomas Edison], but it’s hard to deny the genius of his self-proclaimed personal favorite invention: the phonograph. Capturing sound as physical patterns on a malleable medium was truly revolutionary, and the basic technology that served as the primary medium of recorded sound for more than a century and built several major industries is still alive and kicking today.

With so much technological history behind it, what’s the aspiring inventor to do when the urge to spin your own phonograph records strikes? Easy — cut them from wood with a CNC router. At least that’s how [alnwlsn] rolled after the “one-percent inspiration” hit him while cutting a PCB with his router. Reasoning that the tracks on the copper were probably about as fine as the groove on a record, he came up with some math to describe a fine-pitch spiral groove and overlay data from a sound file, and turn the whole thing into G-code.

For a suitable medium, he turned to the MDF spoil board used to ship PCB stencils, which after about three hours of milling resulted in a rather hairy-looking 78-RPM record. Surprisingly, the record worked fairly well on a wind-up Victrola. The spring-powered motor was a little weak for the heavy wooden record and needed a manual assist, but you can more or less clearly hear the 40-second recording. Even more surprising was how much better the recording sounded when the steel needle was replaced with a chunk of toothpick. You can check out the whole thing in the video below, and you’ll find the G-code generation scripts over on GitHub.

Is all this talk about reproducing music using wiggly lines confusing you? Woah, there, whippersnapper — check out [Jenny]’s primer for the MP3 generation for the background you need.

There’s a military adage that no plan survives first contact with the enemy. While we haven’t gone to war with Mars, at least not yet, it does seem to be a place where the best-laid scientific plans are tested in the extreme. And the apparent failure of Perseverance to retrieve its first Martian core sample is yet another example of just how hard it is to perform geotechnical operations on another planet.

To be sure, a lot about the first sampling operation went right, an especially notable feat in that the entire process is autonomous. And as we’ve previously detailed, the process is not simple, involving three separate robotic elements that have to coordinate their operations perfectly. Telemetry indicates that the percussive drill on the end of the 2.1 m robotic arm was able to use its hollow coring bit to drill into the rock of Jezero crater, and that the sample tube inside the coring bit was successfully twisted to break off the core sample.

But what was supposed to happen next — jamming of the small core sample inside the sample tube — appears not to have happened. This was assessed by handing the sample tube off to the Sample Handling Arm in the belly of Perseverance, where a small probe is used to see how much material was recovered — none, in this case. NASA/JPL engineers then began a search for the problem. Engineering cameras didn’t reveal the core sample on the Martian surface, meaning the sample handling robots didn’t drop it. The core sample wasn’t in the borehole either, which would have meant the camming mechanism designed to retain the core didn’t work. The borehole, though, looked suspicious — it appears not to be deep enough, as if the core sample crumbled to dust and packed into the bottom of the hole.

If this proves to be the cause of the failure, it will be yet another example of Martian regolith not behaving as expected. For InSight, this discovery was a death knell to a large part of its science program. Thankfully, Perseverance can pick up and move to better rock, which is exactly what it will be doing in September. They still have 42 unused sample tubes to go, so here’s to better luck next time.

[Featured images: NASA/JPL-Caltech]

With the roughly 20-day wide launch window for the Mars 2020 mission rapidly approaching, the hype train for the next big mission to the Red Planet is really building up steam. And with good reason — the Mars 2020 mission has been in the works for a better part of a decade, and as we reported earlier this year, the rover it’s delivering to the Martian surface, since dubbed Perseverance, will be among the most complex such devices ever fielded.

“Percy” — come on, that nickname’s a natural — is a mobile laboratory, capable of exploring the Martian surface in search of evidence that life ever found a way there, and to do the groundwork needed if we’re ever to go there ourselves. The nuclear-powered rover bristles with scientific instruments, and assuming it survives the “Seven Minutes of Terror” as well as its fraternal twin Curiosity did in 2012, we should start seeing some amazing results come back.

No prior mission to Mars has been better equipped to answer the essential question: “Are we alone?” But no matter how capable Perseverance is, there’s a limit to how much science can be packed into something that costs millions of dollars a kilogram to get to Mars. And so NASA decided to equip Perseverance with the ability to not only collect geological samples, but to package them up and deposit them on the surface of the planet to await a future mission that will pick them up for a return trip to Earth for further study. It’s bold and forward-thinking, and it’s unlike anything that’s ever been tried before. In a lot of ways, Perseverance’s sample handling system is the rover’s raison d’être, and it’s the subject of this deep dive.

Three Robots in One

NASA has done its usual admirable job of communicating with the public about the Mars 2020 mission, and part of the outreach includes this recent video that shows off a little of the engineering that went into the sample handling system. Honestly, though, for as much tech eye candy as that video had, it only served to whet my appetite. There was so much going on that I had to find out more.

To get a bit of the inside story, I turned to Kelly Palm, one of the JPL engineers seen in the video below. As the Integration and Test Lead for the Sample Caching System (SCS), she’s pretty busy these days, but she graciously fielded my questions and helped give me an idea of what went into building and testing such a complex piece of equipment.

First of all, the SCS is really not just one but three separate robots, each with a specific set of jobs. The “business end” of the SCS is the 2-meter-long robot arm mounted to the front of the vehicle. Like Curiosity before it, the arm carries a turret that’s laden with scientific instruments, sensors, and cameras, as well as the tools necessary for boring into Martian rocks and taking samples. But unlike its predecessor, where the rock drill was designed to abrade rocks and produce a powder that could be easily analyzed by onboard instruments, the Perseverance drill is specialized for obtaining core samples, suitable for both on-board study and in terrestrial labs once the samples are returned.

The drill in the robot arm’s turret is a pretty versatile tool. With the help of the bit carousel (more about which is below) the drill can attach bits designed for different jobs. The drill is capable of running in either a simple rotary mode or in a percussive mode, similar to a hammer drill. A small onboard tank of purified nitrogen is used to gently remove dust generated by coring operations.

Coring into rock to a limited depth using a cylindrical bit raises a question: how exactly is the core recovered? On Earth, the answer would be to use a second tool to pry at the cylinder of rock left behind after the coring bit is removed. While something like that could certainly work on Mars too, especially with a robotic arm at your disposal, NASA came up with a far more clever system.

According to design tests run by a company called Honeybee Robotics in 2014, liberating the core from the parent rock and enclosing it the sample tube in which it will live until being reopened in a lab on Earth is a one-step process. Nestled inside the coring bit is a titanium sample tube. During coring, the axis of the sample tube and the coring bit are aligned with each other, so that the tube slips over the rock core as drilling proceeds. At the proper depth, the sample tube is rotated slightly off-axis, exerting enough force on the base of the core sample to break it off from the parent rock. The core is retained by a lip on the inside of the coring bit, allowing it to be removed from the hole, already within the titanium sample tube in which it will remain until the sample return mission.

Sealed with a Ram

The bit carousel is the next robot in the sample caching process. Sitting at the front of the rover chassis, the bit carousel is outwardly simple — just a rotating turret that transports bits to and from storage in the belly of Perseverance. But what it lacks in complexity is more than made up for by its clever design. The body of the carousel is a wheel with stations around the edge. Each station is at a 45° angle relative to the rotor’s axis, which itself is oriented 45° to the long axis of the chassis. The combination of angles means that a tube can transition from vertical to horizontal just by rotating the carousel with a single motor. There are plenty of sensors and actuators that ensure everything is lined up, of course, but the simplicity of the design is really something.

The ability to transfer tools and samples between horizontal and vertical orientations is critical to the sample caching mission, since the robot that takes care of storing everything lives inside the forward section of the rover’s chassis. The Sample Handling Arm, or SHA, looks a little like the SCARA (selective compliance articulated robot arm) robots that are prevalent in semiconductor fabs. The SHA is capable of accessing multiple locations inside the sample caching compartment and transferring between them and the bit carousel presentation area. To clear the instruments and sample tubes that take up most of the space in the bay, the SHA has an additional Z-axis so that the whole thing can drop below the bottom edge of the rover chassis. In addition to 42 storage silos for core and regolith sample tubes, the SHA can reach storage for a number of tools and attachments, plus instruments for doing some preliminary analysis of the samples, such as volume assessment and imaging.

Once a sample tube is filled, it needs to be hermetically sealed to ensure that the contents will survive for an indeterminate amount of time on the Martian surface as well as withstand the rigors of the eventual trip back to Earth. The seal has to be made without contaminating the sample, so no adhesives can be used, and no heat can be used either, lest the sample be subjected to extreme temperatures.

To seal a sample tube, the SHA brings it over to one of seven seal dispensers. A cup-shaped plug is dropped into the open end of the tube by a dispenser. The plugged tube is then moved to a sealing station, which uses a motor-driven ram to drive a tapered ferrule down a guide rod inside of the plug. As the ferrule is pressed downward, the rim of the plug expands, driving a sharp tooth on its outside circumference into the inner wall of the sample tube. The end result is essentially a cold-welded bond between the cap and the sample tube, hermetically sealing the tube and protecting the sample from contamination.

Return to Sender

Once a sample has been sealed in its titanium sarcophagus, it’s ready to be deposited onto the Martian surface. Most mission profiles that I could find refer to the use of “depot caching”, where Perseverance repeatedly returns to a single location from various regions of interest to deposit sample tubes. This makes perfect sense; finding a big pile of 42 titanium tubes is probably a far easier task for a future sample recovery mission than roaming about looking for individual tubes dropped where they were taken.

Still, whatever robot is sent to clean up after Perseverance has its work cut out for it; since the SHA cannot reach down to the surface, the tubes will have to be dropped, which means an orderly stack of sample tubes will likely not be what the recovery robot will find. Whatever follows in Perseverance’s tracks is going to need the agility to pick up and safely stow every single precious sample tube regardless of its orientation, possibly after digging it out of wind-blown regolith, and the intelligence to do it all autonomously.

With some luck, Perseverance will soon be on its way to Mars, and both when it launches and when it lands in February, we’ll be glued to our seats waiting for results. We’ll also be following the development of the return mission, which could prove to be even more challenging and require even cooler engineering to pull off.

Featured images: NASA/JPL-Caltech

We’re always on the lookout for unexpected budget builds here at Hackaday, and stumbling across a low-cost, DIY version of an instrument that sells for tens of thousands of dollars is always a treat. And so when we saw a tip for a homebrew gas chromatograph in the tips line this morning, we jumped on it. (Video embedded below.)

For those who haven’t had the pleasure, gas chromatography is a chemical analytical method that’s capable of breaking a volatile sample up into its component parts. Like all chromatographic methods, it uses an immobile matrix to differentially retard the flow of a mobile phase containing the sample under study, such that measurement of the transit time through the system can be made and information about the physical properties of the sample inferred.

The gas chromatograph that [Chromatogiraffery] built uses a long stainless steel tube filled with finely ground bentonite clay, commonly known as kitty litter, as the immobile phase. A volatile sample is injected along with an inert carrier gas – helium from a party balloon tank, in this case – and transported along the kitty litter column by gas pressure. The sample interacts with the column as it moves along, with larger species held back while smaller ones speed along. Detection is performed with thermal conductivity cells that use old incandescent pilot lamps that have been cracked open to expose their filaments to the stream of gas; using a Wheatstone bridge and a differential amp, thermal differences between the pure carrier gas and the eluate from the column are read and plotted by an Arduino.

The homebrew GC works surprisingly well, and we can’t wait for [Chromatogiraffery] to put out more details of his build.

Thanks to [Heye] for the tip.

We humans are good at a lot of things, but making holes in the ground has to be among our greatest achievements. We’ve gone from grubbing roots with a stick to feeding billions with immense plows pulled by powerful tractors, and from carving simple roads across the land to drilling tunnels under the English Channel. Everywhere we go, we move dirt and rock out of the way, remodeling the planet to suit our needs.

Other worlds are subject to our propensity for digging holes too, and in the 50-odd years that we’ve been visiting or sending robots as our proxies, we’ve made our marks on quite a few celestial bodies. So far, all our digging has been in the name of science, either to explore the physical and chemical properties of these far-flung worlds in situ, or to actually package up a little bit of the heavens for analysis back home. One day we’ll no doubt be digging for different reasons, but until then, here’s a look at the holes we’ve dug and how we dug them.

The Moon

For the purposes of this article, I’m going to just discuss the times that missions have intentionally dug, drilled, or blasted holes in celestial bodies for the purpose of exploration. This leaves out important but purely symbolic acts of excavation, like leaving footprints and planting flags on the Moon. It also excludes all of the dozens of times spacecraft were intentionally or accidentally crashed into things. Many such early missions to the Moon ended that way, with the first being the Luna 2, a Soviet mission that impacted in September of 1959, less than two years after Sputnik.

It wouldn’t be until late December of 1966 that the first craft designed to dig a hole would land on the Moon. Luna 13‘s mission was to assess the suitability of the lunar surface for a manned Soviet landing that would never come. The main instrument was a penetrometer, attached to the end of a long boom deployed after landing. The instrument had a short rod with a sharpened tip and a small solid-propellant rocket motor to drive it down into the lunar surface. It penetrated 45 cm into the regolith and measured the density and consistency of the soil.

That first human-made hole in the Moon was followed four months later by Surveyor 3, one of a series of American probes designed to find suitable locations for landing the planned Apollo missions. The lander carried a Soil Mechanics Surface Sampler (SMSS), and extendible pantograph arm with a small soil scoop on the end. The arm had azimuth and elevation control motors in its base, allowing it to range in a wide arc, and telemetry allowed engineers to infer the forces on the regolith from the current drawn by the motors. The SMSS was very busy for 18 hours, controlled in near real-time through the lander’s slow-scan TV camera. It dug multiple trenches, pressed down on the lunar surface, and did impact tests by dropping the scoop from a height. It even picked up a rock and tried to crush it; sadly, the scoop didn’t have enough oomph for that.

Subsequent Surveyor missions also gathered SMSS data, sufficient to be reasonably sure the Apollo missions would be able to land safely and return with samples from the Moon’s surface. Apollo 11 was the first successful sample return mission, and returning samples from the Moon was considered so important by mission planners that one of the very first things Neil Armstrong did after setting foot on the Moon was to scoop up a small “contingency sample” with a plastic bag on a sampling stick. The sample, tucked into a pocket on his suit, was intended to at least get some bit of the Moon home, in case they needed to abort the mission before collecting anything else. It was the first few grams of the 382 kg (!) of soil and rocks returned over the six Apollo landings, some scooped up, some shoveled, and some obtained by core drilling.

Mars

While most of the action of the late 1960s and early 1970s focused on the Moon, our planetary neighbor was also slated for exploration. Soviet attempts to visit the Red Planet began in 1960, but it wouldn’t be until 1971 that they would land a spacecraft successfully. The Mars 3 mission had a lander that looked remarkably like the Luna program landers, and carried not only a robotic arm with a scoop for sampling the Martian soil, but a small rover that was supposed to scoot about autonomously on skids and contained a penetrometer similar to that on Luna 13. Sadly, contact was lost with the probe a mere 15 seconds after it landed, and none of the planned science was performed.

Five years later, the American Viking program succeeded with two Mars landers, Viking 1 and Viking 2. Both landers were identical and were specifically designed to sample the Martian soil to search for life. The sampler arm was an ingenious device, a boom that could extend 10 feet (3 meters) and drive the sampler head into the soil but still retract enough to deliver the samples to the various science packages on the top of the lander. The boom was basically two large stainless steel bands, somewhat like giant tape measure blades with the concave sides facing each other and connected at the edges. The boom, containing a ribbon cable for the sampler head, flattens as it rolls onto a reel and expands as it pays out, making it stiff enough to dig into the soil.

The results of Viking’s chemical and biochemical analysis of the Martian soils were, unfortunately, inconclusive. Further excavation of the Red Planet would have to wait a while, as mission after mission sent to Mars failed. Finally, in 2003 the Mars Exploration Rovers Spirit and Opportunity arrived and began their epic 15-year trek across the planet. Each rover carried a Rock Abrasion Tool (RAT), a small diamond grinding wheel on the end of a robotic arm. Pressed up against a rock, it spun at 3000 RPM and ground holes up to 5 mm deep, exposing unweathered rock for the rovers spectrometer and other instruments to analyze.

Still, all these excavations on the Moon and Mars have barely scratched the surface. That’s changing now with the Mars InSight mission. InSight itself touched down on Mars back in November, and has since deployed an instrument intended to make the deepest extraterrestrial hole yet. The Heat Flow and Physical Properties Package (HP³), placed on the surface by the lander’s robotic arm, contains a self-drilling sensor package, dubbed “the mole.” Operating in much the same way as an ordinary cordless impact driver, the mole is supposed to burrow into the Martian regolith, trailing a tail of sensors. The maximum depth it can reach is 5 meters, but it’s currently stuck at about 30 centimeters. It may have hit a rock or patch of gravel, in which case it doesn’t look good for going any deeper.

The Minor Planets

NASA has its own asteroid sample return mission in progress, OSIRIS-REx, currently surveying asteroid 101955 Bennu. Once it finds a suitable site, the probe will descend to let the Touch-and-Go Sample Acquisition Mechanism (TAGSAM) contact the surface. TAGSAM’s excavations will be decidedly less energetic than the Hayabusa probes; regolith will be blown into the sampler using puffs of nitrogen gas. That will be enough to collect the minimum 60 grams of material needed for analysis on Earth.

Given the treasure trove of scientific data generated by analyzing these samples, it’s not likely that we’ll stop scooping, blasting, scraping, and puffing holes in other worlds anytime soon. Wherever we go, if there’s a surface to dig into, you can bet we’ll find a way to do it.

Too many college students have been subject to teachers’ aids who think they are too clever to be stuck teaching mere underclassmen. For that reason, [The Thought Emporium] is important because he approaches learning with gusto and is always ready to learn something new himself and teach anyone who wants to learn. When he released a video about staining and observing plant samples, he avoided the biggest pitfalls often seen in college or high school labs. Instead of calling out the steps by rote, he walks us through them with useful camera angles and close-ups. Rather than just pointing at a bottle and saying, “the blue one,” he tells us what is inside and why it is essential. Instead of telling us precisely what we need to see to get a passing grade, he lets our minds wonder about what we might see and shows us examples that make the experiment seem exciting. The video can also be seen below the break.

The process of staining can be found in a biology textbook, and some people learn best by reading, but we haven’t read a manual that makes a rudimentary lab seem like the wardrobe to Narnia, so he gets credit for that. Admittedly, you have to handle a wicked sharp razor, and the chance of failure is never zero. In fact, he will tell you, the opportunities to fail are everywhere. The road to science isn’t freshly paved, it needs pavers.

If a biology lab isn’t in your personal budget, a hackerspace may have one or need one. If you are wondering where you’ve heard [The Thought Emporium]’s voice before, it is because he is fighting lactose intolerance like a hacker.

There are two major effects that are purely in the digital domain. The first is the sample rate reducer. This has a few interesting applications. Because [Shannon] and [Nyquist] say we can only reproduce audio signals less than half of the sample rate; if you run some audio through a sample rate reducer set to 1kHz, it’ll sound like crap, but you’ll also only get bass.

The bitcrusher is a little different. Instead of recording samples of 256 values for 8-bit audio or ~65000 values for 16-bit audio, a one-bit bitcrusher only records one value – on or off. Play it through a speaker at a decent sample rate, and you can still hear it. It sounds like a robotic nightmare, but it’s still there.

[Electronoob] created his bitcrusher purely in software, sending the resulting bitcrushed and much smaller file to an Arduino for playback. Interestingly, he’s also included the ability to downsample audio, giving is project both pure digital effects for the price of one. 1-bit audio is a bit rough on the ears, but 2, 3, and 4-bit audio starts to sound pretty cool, and something that would feel at home in some genres of music.