ISS Artificial Gravity Study Shows Promise For Long Duration Spaceflight

The International Space Station is humanity’s most expensive gym membership.

Since the earliest days of human spaceflight, it’s been understood that longer trips away from Earth’s gravity can have a detrimental effect on an astronaut’s body. Floating weightless invariably leads to significantly reduced muscle mass in the same way that a patient’s muscles can atrophy if they spend too much time laying in bed. With no gravity to constantly fight against, an astronauts legs, back, and neck muscles will weaken from disuse in as little as a week. While this may not pose an immediate problem during spaceflight, astronauts landing back on Earth in this physically diminished state are at a higher risk of injury.

Luckily this problem can be largely mitigated with rigorous exercise, and any orbiting vessel spacious enough to hold human occupants for weeks or months will by necessity have enough internal volume to outfit it with basic exercise equipment such as a treadmill or a resistance machine. In practice, every space station since the Soviet Union’s Salyut 1 in 1971 has featured some way for its occupants to workout while in orbit. It’s no replacement for being on Earth, as astronauts still return home weaker than when they left, but it’s proven to be the most practical approach to combating the debilitating aspects of long duration spaceflight.

Early NASA concept for creating artificial gravity.

Of course, there’s an obvious problem with this: every hour spent exercising in space is an hour that could be better spent doing research or performing maintenance on the spacecraft. Given the incredible cost of not just putting a human into orbit, but keeping them there long-term, time is very literally money. Which brings us back to my original point: astronauts spending two or more hours each day on the International Space Station’s various pieces of exercise equipment just to stave off muscle loss make it the world’s most expensive gym membership.

The ideal solution, it’s been argued, is to design future spacecraft with the ability to impart some degree of artificial gravity on its passengers through centripetal force. The technique is simple enough: just rotate the craft along its axis and the crew will “stick” to the inside of the hull. Unfortunately, simulating Earth-like gravity in this way would require the vessel to either be far larger than anything humanity has ever launched into space, or rotate at a dangerously high speed. That’s a lot of risk to take on for what’s ultimately just a theory.

But a recent paper from the University of Tsukuba in Japan may represent the first real steps towards the development of practical artificial gravity systems aboard crewed spacecraft. While their study focused on mice rather than humans, the results should go a long way to codifying what until now was largely the stuff of science fiction.

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How The LIGO Observatory Detects Gravitational Waves

Gravity is one of the more obvious forces in the universe, generally regarded as easily noticeable by the way apples fall from trees. However, the underlying mechanisms behind gravity are inordinately complex, and the subject of much study to this day.

A major component of this study is around the concept of gravitational waves. First posited by Henri Poincaré in 1905, and later a major component of Einstein’s general theory of relativity, they’re a phenomena hunted for by generations of physicists ever since. For the team at the Laser Interferometer Gravitational-wave Observatory, or LIGO, finding direct evidence of gravitational waves is all in a day’s work.

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Hackaday Links: March 14, 2021

It’ll be Pi Day when this article goes live, at least for approximately half the globe west of the prime meridian. We always enjoy Pi Day, not least for the excuse to enjoy pie and other disc-shaped foods. It’s also cool to ponder the mysteries of a transcendental number, which usually get a good treatment by the math YouTube community. This year was no disappointment in this regard, as we found two good pi-related videos, both by Matt Parker over at Standup Maths. The first one deals with raising pi to the pi to the pi to the pi and how that may or may not result in an integer that’s tens of trillions of digits long. The second and more entertaining video is a collaboration with Steve Mould which aims to estimate the value of pi by measuring the volume of a molecular monolayer of oleic acid floating on water. The process was really interesting and the results were surprisingly accurate; this might make a good exercise to do with kids to show them what pi is all about.

Remember basic physics and first being exposed to the formula for universal gravitation? We sure do, and we remember thinking that it should be possible to calculate the force between us and our classmates. It is, of course, but actually measuring the attractive force would be another thing entirely. But researchers have done just that, using objects substantially smaller than the average high school student: two 2-mm gold balls. The apparatus the Austrian researchers built used 90-milligram gold balls, one stationary and one on a suspended arm. The acceleration between the two moves the suspended ball, which pivots a mirror attached to the arm to deflect a laser beam. That they were able to tease a signal from the background noise of electrostatic, seismic, and hydrodynamic forces is quite a technical feat.

We noticed a lot of interest in the Antikythera mechanism this week, which was apparently caused by the announcement of the first-ever complete computational model of the ancient device’s inner workings. The team from University College London used all the available data gleaned from the 82 known fragments of the mechanism to produce a working model of the mechanism in software. This in turn was used to create some wonderful CGI animations of the mechanism at work — this video is well worth the half-hour it takes to watch. The UCL team says they’re now at work building a replica of the mechanism using modern techniques. One of the team says he has some doubts that ancient construction methods could have resulted in some of the finer pieces of the mechanism, like the concentric axles needed for some parts. We think our friend Clickspring might have something to say about that, as he seems to be doing pretty well building his replica using nothing but tools and methods that were available to the original maker. And by doing so, he managed to discern a previously unknown feature of the mechanism.

We got a tip recently that JOGL, or Just One Giant Lab, is offering microgrants for open-source science projects aimed at tackling the problems of COVID-19. The grants are for 4,000€ and require a minimal application and reporting process. The window for application is closing, though — March 21 is the deadline. If you’ve got an open-source COVID-19 project that could benefit from a cash infusion to bring to fruition, this might be your chance.

And finally, we stumbled across a video highlighting some of the darker aspects of amateur radio, particularly those who go through tremendous expense and effort just to be a pain in the ass. The story centers around the Mt. Diablo repeater, an amateur radio repeater located in California. Apparently someone took offense at the topics of conversation on the machine, and deployed what they called the “Annoy-o-Tron” to express their displeasure. The device consisted of a Baofeng transceiver, a cheap MP3 player loaded with obnoxious content, and a battery. Encased in epoxy resin and concrete inside a plastic ammo can, the jammer lugged the beast up a hill 20 miles (32 km) from the repeater, trained a simple Yagi antenna toward the site, and walked away. It lasted for three days and while the amateurs complained about the misuse of their repeater, they apparently didn’t do a thing about it. The jammer was retrieved six weeks after the fact and hasn’t been heard from since.

A Scientist Made An Artificial Black Hole In The Lab, And You Won’t Believe What Happened Next

OK, that was a little click-baity, but then again, so was the announcement this week that a scientist had confirmed Hawking radiation with a lab-grown black hole. It sure got our attention, at least.

As it turns out, the truth is both less and more than meets the eye. The article above was eventually edited to better reflect the truth that, alas, we have not yet found a way to create objects so massive that even light cannot escape them. Instead, physicist [Jeff Steinhauer] and colleagues at the Technion-Israel Institute of Technology have developed an acoustic model of black holes, which is what was used to observe the equivalent of Hawking radiation for the first time. Hawking radiation is the theoretical exception to the rule that nothing makes it out of a black hole and would imply that black holes evaporate over time. The predicted radiation would be orders of magnitude weaker than the background radiation, though, making it all but impossible to detect.

That’s where [Steinhauer]’s sonic black holes come in. In these experiments, phonons, packets of mechanical vibrations that stand in for photons, are trapped in a fast-moving stream of fluid. The point in the stream where its speed straddles the local speed of sound is the equivalent to a real black hole’s event horizon; phonons inside that boundary can never escape. Except, of course, for the sonic equivalent of Hawking radiation, which the researchers found after 97,000 attempts.

When we first stumbled upon this story, we assumed a lab-grown black hole, even an acoustic analog, would take a CERN’s-worth of equipment to create. It turns out to be far simpler than that; [Steinhauer], in fact, built his black hole machine singlehandedly from relatively simple equipment. The experiments do require temperatures near absolute zero and a couple of powerful lasers, so it’s not exactly easy stuff; still, we can’t help but wonder if sonic black holes are within the reach of the DIY community. Paging [Ben Krasnow] and [Sam Zeloof], among others.

[Featured image credit: Nitzan Zohar, Office of the Spokesperson, Technion]

Companies Have New Take On Old Energy Storage Tech

According to Spectrum, several companies are poised to make a splash storing energy with gravity. That sounds fancy and high tech at first, but is it, really? Sure, we usually think of energy storage as some sort of battery, but there are many energy storage systems that use water falling, for example, which is almost what this new technology is all about. Almost, since instead of water these new systems move around multi-ton blocks.

The idea itself is nothing new. You probably learned in high school that you have kinetic energy when a rock rolls down a hill, but a rock sitting on a mountain immobile has potential energy. These systems use the same idea. Moving the “rock” up stores energy and letting it fall releases the same energy. The big difference between the systems is what “up” means.

For Swiss company Energy Vault, the 35 metric ton bricks rise into the air manipulated by towers that look like alien construction cranes. To store energy, the crane builds a tower of bricks around itself. When the bricks return to the ground, they form a lower ring around the tower.

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Possible Fifth Force Of Nature Found

Over the years, humans have come up with four forces that can be used to describe every single interaction in the physical world. They are gravity, electromagnetism, the weak nuclear force that causes particle decay, and the strong nuclear force that binds quarks into atoms. Together, these have become the standard model of particle physics. But the existence of dark matter makes this model seem incomplete. Surely there must be another force (or forces) that explain both its existence and the reason for its darkness.

Image via Business Insider

Hungarian scientists from the Atomki Nuclear Research Institute led by Professor Attila Krasznahorkay believe they have found evidence of a fifth force of nature. While monitoring an excited helium atom’s decay, they observed it emitting light, which is not unusual. What is unusual is that the particles split at a precise angle of 115 degrees, as though they were knocked off course by an invisible force.

The scientists dubbed this particle X17, because they calculated its mass at 17 megaelectronvolts (MeV). One electron Volt describes the kinetic energy gained by a single electron as it moves from zero volts to a potential of one volt, and so a megaelectronvolt is equal to the energy gained when an electron moves from zero volts to one million volts.

What Are Those First Four, Again?

Let’s start with the easy one, gravity. It gives objects weight, and keeps things more or less glued in place on Earth. Though gravity is a relatively weak force, it dominates on a large scale and holds entire galaxies together. Gravity helps us work and have fun. Without gravity, there would be no water towers, hydroelectric power plants, or roller coasters.

Lightning via Wikimedia Commons

The electromagnetic force is a two-headed beast that dominates at the human scale. Almost everything we are and do is underpinned by this force that surrounds us like an ethereal soup. Electricity and magnetism are considered a dual force because they work on the same principle — that opposite forces attract and like forces repel.

This force holds atoms together and makes electronics possible. It’s also responsible for visible light itself. Each fundamental force has a carrier particle, and for electromagnetism, that particle is the photon. What we think of as visible light is the result of photons carrying electrostatic force between electrons and protons.

The weak and strong nuclear forces aren’t as easy to grasp because they operate at the subatomic level. The weak nuclear force is responsible for beta decay, where a neutron can turn into a proton plus an electron and anti-neutrino, which is one type of radioactive decay. Weak interactions explain how particles can change by changing the quarks inside them.

The strong nuclear force is the strongest force in nature, but it only dominates at the atomic scale. Imagine a nucleus with multiple protons. All those protons are positively charged, so why don’t they repel each other and rip the nucleus apart? The strong nuclear force is about 130x stronger than the electromagnetic force, so when protons are close enough together, it will dominate. The strong nuclear force holds both the nucleus together as well as the nucleons themselves.

The Force of Change

Suspicion of a fifth force has been around for a while. Atomki researchers observed a similar effect in 2015 when they studied the light emitted during the decay of a beryllium-8 isotope. As it decayed, the constituent electrons and positrons consistently repelled each other at another strange angle — exactly 140 degrees. They dubbed it a “protophobic” force, as in a force that’s afraid of protons. Labs around the world made repeated attempts to prove the discovery a fluke or a mistake, but they all produced the same results as Atomki.

Professor Attila Krasznahorkay and his team published their observations in late October, though the paper has yet to be peer-reviewed. Now, the plan at Atomki is to observe other atoms’ decay. If they can find a third atom that exhibits this strange behavior, we may have to take the standard model back to the drawing board to accommodate this development.

So what happens if science concludes that the X17 particle is evidence of a fifth force of nature? We don’t really know for sure. It might offer clues into dark matter, and it might bring us closer to a unified field theory. We’re at the edge of known science here, so feel free to speculate wildly in the comments.

Main image via Index

Gravity Simulations With An FPGA

Gravity can be a difficult thing to simulate effectively on a traditional CPU. The amount of calculation required increases exponentially with the number of particles in the simulation. This is an application perfect for parallel processing.

For their final project in ECE5760 at Cornell, [Mark Eiding] and [Brian Curless] decided to use an FPGA to rapidly process gravitational calculations. This allows them to simulate a thousand particles at up to 10 frames per second. With every particle having an attraction to every other, this works out to an astonishing 1 million inverse-square calculations per frame!

The team used an Altera DE2-115 development board to build the project. General operation is run by a Nios II processor, which handles the VGA display, loads initial conditions and controls memory. The FPGA is used as an accelerator for the gravity calculations, and lends the additional benefit of requiring less memory access operations as it runs all operations in parallel.

This project is a great example of how FPGAs can be used to create serious processing muscle for massively parallel tasks. Check out this great article on sorting with FPGAs that delves deeper into the subject. Video after the break.

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