Lagrange Points And Why You Want To Get Stuck At Them

October 9, 2024 by Maya Posch 35 Comments

Visualization of the Sun-Earth Lagrange points.

Orbital mechanics is a fun subject, as it involves a lot of seemingly empty space that’s nevertheless full of very real forces, all of which must be taken into account lest one’s spacecraft ends up performing a sudden lithobraking maneuver into a planet or other significant collection of matter in said mostly empty space. The primary concern here is that of gravitational pull, and the way it affects one’s trajectory and velocity. With a single planet providing said gravitational pull this is quite straightforward to determine, but add in another body (like the Moon) and things get trickier. Add another big planetary body (or a star like our Sun), and you suddenly got yourself the restricted three-body problem, which has vexed mathematicians and others for centuries.

The three-body problem concerns the initial positions and velocities of three point masses. As they orbit each other and one tries to calculate their trajectories using Newton’s laws of motion and law of universal gravitation (or their later equivalents), the finding is that of a chaotic system, without a closed-form solution. In the context of orbital mechanics involving the Earth, Moon and Sun this is rather annoying, but in 1772 Joseph-Louis Lagrange found a family of solutions in which the three masses form an equilateral triangle at each instant. Together with earlier work by Leonhard Euler led to the discovery of what today are known as Lagrangian (or Lagrange) points.

Having a few spots in an N-body configuration where you can be reasonably certain that your spacecraft won’t suddenly bugger off into weird directions that necessitate position corrections using wasteful thruster activations is definitely a plus. This is why especially space-based observatories such as the James Webb Space Telescope love to hang around in these spots.

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Running Game Boy Games On STM32 MCUs Is Peanuts

October 8, 2024 by Maya Posch 3 Comments

Using a STM32F429 Discovery board [Jan Zwiener] put together a Game Boy-compatible system called STM32Boy. It is based around the Peanut-GB Game Boy emulator core, which is a pretty nifty and fast single-header GB emulator library in C99. Considering that the average 32-bit MCU these days is significantly faster than the ~4 MHz 8-bit Sharp SM83 (Intel 8080/Zilog Z80 hybrid) in the original Game Boy it’s probably no surprise that the STM32F429 (up to 180 MHz) can emulate this 8-bit SoC just fine.

Since Peanut-GB is a library, the developer using it is expected to provide their own routines to read and write RAM and ROM and to handle errors. Optional are the line drawing, audio read/write and serial Tx/Rx functions, with the library providing reset and a host of other utility functions. Audio functionality is provided externally, such as using the provided MiniGB APU. Although fast, it comes with a range of caveats that limit compatibility and accuracy.

For STM32Boy, [Jan] uses the LCD screen that’s on the STM32 development board to render the screen on, along with a Game Boy skin. The LCD’s touch feature is then used for the controls, as can be elucidated from the main source file. Of note is that the target GB ROM is directly compiled into the firmware image rather than provided via an external SD card. This involves using the xxd tool to create a hex version of the ROM image that can be included. Not a bad way to get a PoC up and running, but we imagine that if you want to create a more usable GB-like system it should at least be able to play more than one game without having to reflash the MCU.

Using Donor Immune Cells To Mass-Produce CAR-T Autoimmune Therapies

October 7, 2024 by Maya Posch 3 Comments

As exciting as immunotherapies are in terms of fighting cancer, correcting autoimmune disorders and so on, they come with a major disadvantage. Due to the current procedure involving the use of a patient’s own immune (T) cells, this making such therapies rather expensive and involved for the patient. Recent research has therefore focused on answering the question whether T cells from healthy donors could be somehow used instead, with promising results from a recent study on three human patients, as reported in Nature.

The full study results (paywalled) by [Xiaobing Wang] et al. are published in Cell, with the clinical trial details available on the ClinicalTrials.gov website. For this particular trial the goal was to attempt to cure the autoimmune conditions of the three study participants (being necrotizing myopathy (IMNM) and diffuse cutaneous systemic sclerosis (dcSSc)). The T cells used in the study were obtained from a healthy 21-year old woman, and modified with chimeric antigen receptors targeting B (memory) cells. Using CRISPR-Cas9 the T cells were then further modified to prevent the donor cells from attacking the patient’s cells and vice versa.

After injection, the CAR-T cells got to work, multiplying and seeking out the target B cells, including the pathogenic ones underlying the autoimmune conditions. This persisted for a few weeks until the CAR-T cells effectively vanished and new B cells began to emerge, with a clear decrease in autoantibodies. Two months after beginning treatment, all three participants noted marked improvements in their conditions, which persisted at 6 months. For the woman with IMNM, muscle strength had increased dramatically with undetectable autoantibody levels, and the two men with dcSSc saw scar tissue formation reversed and their skin condition improve massively.

It remains to be seen whether this period of remission in these patients is permanent, and whether there any side effects of CAR-T cell therapy. We previously reported on CAR-T cell therapies and the many promises which they hold. Depending on the outcome of these early trials, it could mean that autoimmune conditions, allergies and cancer will soon be worries of the past, marking another massive medical milestone not unlike the invention of vaccines and the discovery of antibiotics.

Vehicle-To-Everything: The Looming Smart Traffic Experience

October 7, 2024 by Maya Posch 47 Comments

Much of a car’s interaction with the world around it is still a very stand-alone, analog experience, regardless of whether said car has a human driver or a self-driving computer system. Mark I eyeballs or equivalent computer-connected sensors perceive the world, including road markings, traffic signs and the locations of other road traffic. This information is processed and the car’s speed and trajectory are adjusted to ideally follow the traffic rules and avoid unpleasant conversations with police officers, insurance companies, and/or worse.

An idea that has been kicked around for a few years now has been to use wireless communication between cars and their environment to present this information more directly, including road and traffic conditions, independent from signs placed near or on the road. It would also enable vehicle-to-vehicle communication (V2V), which somewhat like the transponders in airplanes would give cars and other vehicles awareness of where other traffic is hanging out. Other than V2V, Vehicle-to-Everything (V2X) would also include communication regarding infrastructure (V2I), pedestrians (V2P) and an expansive vehicle-to-network (V2N) that gives off strong Ghost in the Shell vibes.

Is this is the future of road traffic? The US Department of Transport (DOT) seems to think that its deployment will be a good thing, but V2X has been stuck in regulatory hurdles. This may now change, with the DOT releasing a roadmap for its deployment.

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Reversing Type 1 Diabetes With A Patient’s Own Stem Cells

October 6, 2024 by Maya Posch 8 Comments

Type 1 diabetes is an auto-immune condition whereby the patient’s own immune system attacks the pancreatic islets, destroying them in the process. Since these islets are responsible for producing insulin in response to blood sugar (glucose) levels, the patient is thus required to externally inject insulin for the remainder of their life. That was the expected scenario, but it appears that this form of diabetes may soon be treatable, with one woman now being free of the condition for a year already, as reported in Nature, referencing an article by [Shusen Wang] et al. that describes the treatment and the one-year result.

Most notable with this study is that the researchers didn’t use the regular method to create pluripotent stem cells. These cells were extracted from the patient, to revert back to this earlier developmental stage. They were not modified using genes, but rather singular chemicals (PDF). The advantage of this is that it avoids having to modify the cell’s genomes, which could conceivably cause issues like cancer later on. This was one of the first time that this method was used in a human subject, with islet cells formed and about 1.5 million of them injected into the patient’s abdominal muscles, a novel site for this procedure.

This location made these islets easy to keep track of, and easier to remove in case of any issues compared to the usual injection site within the liver. Fortunately for this woman, no complications occurred and one year later she is still free of any diabetes symptoms. Two other patients in the trial are also seeing very positive results, leaving only the question of whether the auto-immune condition that originally caused the islet destruction still exists. Since this female patient is taking immunosuppressants for a previous liver transplant it’s a hard to thing to judge, especially since we understand the causes behind type 1 diabetes so poorly.

Regardless, this and other trials using pluripotent cells, transplanted islets and more offer the prospect of a permanent treatment for the many people who suffer from type 1 diabetes.

Featured image: “Human induced pluripotent stem cell colony” National Eye Institute/NIH

2View: The Self-Erasing VHS Tape With Paperclip Hack

October 6, 2024 by Maya Posch 17 Comments

The back of the 2View VHS box. The instructions are all in Dutch, as its (sole) launch market. (Credit: Techmoan, YouTube)

Over the decades the video and music industries have tried a wide range of ways to get consumers to buy ‘cheaper’ versions of albums and music, but then limit the playback in some way. Perhaps one of the most fascinating ones is the 2View, as recently featured by [Matt] over at Techmoan on Youtube. This is a VHS tape which works in standard VHS players and offers you all the goodness that VHS offers, like up to 512 lines of PAL video and hard-coded ads and subtitles, but also is restricted to just playing twice. After this second playback and rewinding, the tape self-erases and is blank, leaving you with just an empty VHS tape you can use for your own recordings.

As a form of analog restrictions management (ARM) it’s pretty simple in how it works, with [Matt] taking the now thankfully erased Coyote Ugly tape apart for a demonstration of the inside mechanism. This consists out of effectively just two parts: one plastic, spring-loaded shape that moves against one of the tape spools and follows the amount of tape, meaning minutes watched, and a second arm featuring a permanent magnet that is retained by an inner track inside the first shape until after rewinding twice it is released and ends up against the second spool, erasing the tape until rewound, after which it catches in a neutral position. This then left an erased tape that could be safely recorded on again.

Although cheaper than a comparable VHS tape without this limit, 2View was released in 2001, when in the Netherlands and elsewhere DVDs were demolishing the VHS market. This, combined with the fact that a simple bent paperclip could be stuck inside to retain the erase arm in place to make it a regular VHS tape, meant that it was really a desperate attempt that quickly vanished off the market

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Voyager 2’s Plasma Spectrometer Turned Off In Power-Saving Measure

October 2, 2024 by Maya Posch 24 Comments

The Voyager 2 spacecraft’s energy budget keeps dropping by about 4 Watt/year, as the plutonium in its nuclear power source is steadily dropping as the isotope decays. With 4 Watt of power less to use by its systems per year, the decision was made to disable the plasma spectrometer (PLS) instrument. As also noted by the NASA Voyager 2 team on Twitter, this doesn’t leave the spacecraft completely blind to plasma in the interstellar medium as the plasma wave subsystem (PWS) is still active. The PLS was instrumental in determining in 2018 that Voyager 2 had in fact left the heliosphere and entered interstellar space. The PLS on Voyager 1 had already broken down in 1980 and was turned off in 2007.

After saving the Voyager 1 spacecraft the past months from a dud memory chip and switching between increasingly clogged up thrusters, it was now Voyager 2’s turn for a reminder of the relentless march of time and the encroaching end of the Voyager missions. Currently Voyager 2 still has four active instruments, but by the time the power runs out, they’ll both be limping along with a single instrument, probably somewhere in the 2030s if their incredible luck holds.

This incredible feat was enabled both by the hard work and brilliance of the generations of teams behind the two spacecraft, who keep coming up with new tricks to save power, and the simplicity of the radioisotope generators (RTGs) which keep both Voyagers powered and warm even in the depths of interstellar space.