The Continuing Venusian Mystery Of Phosphine And Ammonia

July 19, 2024 by Maya Posch 18 Comments

The planet Venus is in so many ways an enigma. It’s a sister planet to Earth and also within relatively easy reach of our instruments and probes, yet we nevertheless know precious little about what is going on its surface or even inside its dense atmosphere. Much of this is of course due to planets like Mars getting all the orbiting probes and rovers scurrying around on its barren, radiation-blasted surface, but we had atmospheric probes descend through Venus’ atmosphere, so far to little avail. Back in 2020 speculation arose of phosphine being detected in Venus’ atmosphere, which caused both excitement and a lot of skepticism. Regardless, at the recent National Astronomy Meeting (NAM 2024) the current state of Venusian knowledge was discussed, which even got The Guardian to report on it.

In addition to phosphine, there’s speculation of ammonia also being detectable from Earth, both of which might be indicative of organic processes and thus potentially life. Related research has indicated that common amino acids essential to life on Earth would be stable even in sulfuric droplets like in Venus’ atmosphere. After criticism to the original 2020 phosphine article, [Jane S. Greaves] et al. repeated their observations based on feedback, although it’s clear that the observation of phosphine gas on Venus is not a simple binary question.

The same is true of ammonia, which if present in Venusian clouds would be a massive discovery, which according to research by [William Bains] and colleagues in PNAS could explain many curious observations in Venus’ atmosphere. With so much uncertainty with remote observations, it’s clear that the only way that we are going to answer these questions is with future Venus missions, which sadly remain rather sparse.

If there’s indeed life on Venus, it’ll have a while longer to evolve before we can go and check it out.

Carbon–Cement Supercapacitors Proposed As An Energy Storage Solution

July 19, 2024 by Maya Posch 29 Comments

Although most energy storage solutions on a grid-level focus on batteries, a group of researchers at MIT and Harvard University have proposed using supercapacitors instead, with their 2023 research article by [Nicolas Chanut] and colleagues published in Proceedings of the National Academy of Sciences (PNAS). The twist here is that rather than any existing supercapacitors, their proposal involves conductive concrete (courtesy of carbon black) on both sides of the electrolyte-infused insulating membrane. They foresee this technology being used alongside green concrete to become part of a renewable energy transition, as per a presentation given at the American Concrete Institute (ACI).

Functional carbon-cement supercapacitors (connected in series) (Credit: Damian Stefaniuk et al.)

Putting aside the hairy issue of a massive expansion of grid-level storage, could a carbon-cement supercapacitor perhaps provide a way to turn the concrete foundation of a house into a whole-house energy storage cell for use with roof-based PV solar? While their current prototype isn’t quite building-sized yet, in the research article they provide some educated guesstimates to arrive at a very rough 20 – 220 Wh/m³, which would make this solution either not very great or somewhat interesting.

The primary benefit of this technology would be that it could be very cheap, with cement and concrete being already extremely prevalent in construction due to its affordability. As the researchers note, however, adding carbon black does compromise the concrete somewhat, and there are many questions regarding longevity. For example, a short within the carbon-cement capacitor due to moisture intrusion and rust jacking around rebar would surely make short work of these capacitors.

Swapping out the concrete foundation of a building to fix a short is no small feat, but maybe some lessons could be learned from self-healing Roman concrete.

Las Vegas’ Sphere: Powered By Nvidia GPUs And With Impressive Power Bill

July 17, 2024 by Maya Posch 51 Comments

A daytime closeup of the LED pucks that comprise the exosphere of the Sphere in Paradise, Nevada (Credit: Y2kcrazyjoker4, Wikimedia)

As the United States’ pinnacle of extravaganza, the Las Vegas Strip and the rest of the town of Paradise are on a seemingly never-ending quest to become brighter, glossier and more over the top as one venue tries to overshadow the competition. A good example of this is the ironically very uninspiredly named Sphere, which has both an incredibly dull name and yet forms a completely outrageous entertainment venue with a 54,000 m² (~3.67 acre) wrap-around interior LED display (16 x 16K displays) and an exterior LED display (‘Exosphere’) consisting out of 1.23 million LED ‘pucks’. Although opened in September of 2023, details about the hardware that drives those displays have now been published by NVidia in a recent blog post.

Driving all these pixels are around 150 NVidia RTX A6000 GPUs, installed in computer systems which are networked using NVidia BlueField data processing units (DPUs) and NVidia ConnectX-6 NICs (up to 400 Gb/s), with visual content transferred from Sphere Studios in California to the Sphere. All this hardware uses about 45 kW of power when running at full blast, before adding the LED displays and related hardware to the total count, which is estimated to be up to 28 MW of power and causing local environmentalists grief despite claims by the owner that it’ll use solar power for 70% of the power needs, despite many night-time events. Another item that locals take issue with is the amount of light pollution that the exterior display adds.

Although it’s popular to either attack or defend luxurious excesses like the Sphere, it’s interesting to note that the state of Nevada mostly gets its electricity from natural gas. Meanwhile the 2.3 billion USD price tag for the Sphere would have gotten Nevada 16.5% of a nuclear power station like Arizona’s Palo Verde (before the recurring power bill), but Palo Verde’s reactor spheres are admittedly less suitable for rock concerts.

FDM Filament Troubles: Keeping Hygroscopic Materials From Degrading

July 17, 2024 by Maya Posch 18 Comments

Despite the reputation of polymers used with FDM 3D printing like nylon, ABS, and PLA as being generally indestructible, they do come with a whole range of moisture-related issues that can affect both the printing process as well as the final result. While the concept of ‘baking’ such 3D printing filaments prior to printing to remove absorbed moisture is well-established and with many commercial solutions available, the exact extent to which these different polymers are affected, and what these changes look like on a molecular level are generally less well-known.

Another question with such hygroscopic materials is whether the same issues of embrittlement, swelling, and long-term damage inflicted by moisture exposure that affects filaments prior to printing affects these materials post-printing, and how this affects the lifespan of FDM-printed items. In a 2022 paper by Adedotun D. Banjo and colleagues much of what we know today is summarized in addition to an examination of the molecular effects of moisture exposure on polylactic acid (PLA) and nylon 6.

The scientific literature on FDM filaments makes clear that beyond the glossy marketing there is a wonderful world of materials science to explore, one which can teach us a lot about how to get good FDM prints and how durable they will be long-term.

Continue reading “FDM Filament Troubles: Keeping Hygroscopic Materials From Degrading” →

Reverse-Engineering A Shahed-136 Drone Air Data Computer

July 15, 2024 by Maya Posch 22 Comments

Top of the air data computer module, with pressure sensors, RS232 driver and DC-DC converter visible. (Credit: Le Labo de Michel, YouTube)

An air data computer (ADC) is a crucial part of an avionics package that can calculate the altitude, vertical speed, air speed and more from pressure (via pitot tubes) and temperature inputs. When your airplane is a one-way attack drone like Iran’s Shahed-136, you obviously need an ADC as well, but have to focus on making it both cheap and circumvent a myriad of sanctions. As [Michel] recently found out while reverse-engineering one of these ADCs. Courtesy of the Russo-Ukrainian war, hundreds of these Shahed drones are being destroyed every month, with some making it back down again intact enough for some parts to end up on EBay.

The overall design as captured in the schematic is rather straightforward, with the component choice probably being the most notable, as it uses an STM32G071 MCU and Analog Devices ADM3232 RS-232 driver, in addition to the two pressure sensors (by Silicon Microstructures Inc., now owned by TE). The DC-DC converter is a Mornsun URB24055-6WR3.

With the board in working condition, [Michel] hooks it up to a test setup to see the output on the serial interface when applying different pressures to the pressure sensor inputs. This results in a lot of ASCII data being output, all containing different values that were calculated by the firmware on the STM32 MCU. In the drone this data would then be used by the flight computer to make adjustments. Overall it’s a rather basic design that doesn’t seem to have a dedicated temperature sensor either, though [Michel] is still analyzing some details. A firmware dump would of course be rather fascinating as well.

Continue reading “Reverse-Engineering A Shahed-136 Drone Air Data Computer” →

Using Forward- And Reverse-Osmosis To Let Astronaut EVA Suits Produce Fresh Water From Urine

July 14, 2024 by Maya Posch 34 Comments

An uncomfortable reality with the spacesuits used for extravehicular activities (EVA) – commonly referred to as spacewalks – is that the astronaut spends hours in them, during which normal bodily functions like urinating and defecating continue. The current EVA record at the ISS is currently a hair under nine hours, necessitating a new approach. A team of researchers have now pitched the idea of an in-suit water recovery system with an article by [Sofia Etlin] and colleagues as published in Frontiers in Space Technologies.

For the current Extravehicular Mobility Unit (EMU) EVA spacesuit the current solution is what is called the MAG: the Maximum Absorbency Garment, which is effectively a fancy adult diaper with sodium polyacrylate as absorbent for up to 2 L of fluids. It replaced the urine collection device (UCD) that was used until female astronauts joined the astronaut corps in the 1970s. Generally astronauts aim to not defecate until they finish their EVA, which leaves urinating and the related activity of rehydrating as the spacesuits only have 0.95 L of water that has to last the duration of the spacewalk. Continue reading “Using Forward- And Reverse-Osmosis To Let Astronaut EVA Suits Produce Fresh Water From Urine” →

The Mysterious Roman Dodecahedron Was Possibly Just For Knitting

July 14, 2024 by Maya Posch 41 Comments

Over the years archaeological digs of Roman sites have uncovered many of these strange dodecahedrons, usually made out of metal and with various holes in their faces. With no surviving records that describe how they were used, speculation has ranged from jewelry to a knitting aid. In a 2023 video by [Amy Gaines] it is this latter use which is explored, using a 3D printed dodecahedron and some wooden dowels to knit both gold wire and yarn into rather intricate patterns that are also referred to as ‘Viking Knitting’.

As we mentioned previously when yet another one of these dodecahedrons was uncovered, their use was unlikely to be of supreme relevance in military or scientific circles on account of a lack of evidence. What is quite possible is that these were both attractive shapes for jewelry (beads), and useful knitting aids for both jewelry makers (for e.g. gold wire braiding) and quite possibly yarn-related uses. The results which [Amy] demonstrates in the video for the gold wire in particular bear a striking resemblance to ancient braided gold chains on display at the Met and other museums, which leads credence to this theory.

If these items were effectively just common knitting tools, that would explain why the historical record is mum on them, as they would have been as notable as a hammer or a precision lathe used by the ancient Greeks.

Thanks to [john] for the tip.

Continue reading “The Mysterious Roman Dodecahedron Was Possibly Just For Knitting” →