[-] Delta_V@lemmy.world 1 points 2 hours ago

Source for claim of 1% mass loss per cycle:
https://research.tue.nl/en/publications/combustion-of-micron-sized-iron-particles-in-a-drop-tube-reactor/

I think the deciding factor between iron and aluminum comes down to exhaust filtration.

Iron oxide in the exhaust can be collected cheaply with a combination of centrifugal and electrostatic forces and it tends to retain is grain size. Aluminum oxide is lighter, more electrically resistive, and tends to break down into too-small nanoparticles.

Yeah, you'd only need to sinter pellets to pump hydrogen through them in a static pile. A fluidized bed reactor can reduce the iron oxide powder as is, and keeping the temperature lower prevents sticky sintering at the cost of taking longer to complete.

[-] Delta_V@lemmy.world 1 points 16 hours ago

The whole mass of iron powder does not need to be re-ground after every use. From what I've read so far, about half a percent experiences sintering and needs to be re-ground, and another half a percent breaks down into too fine of dust and needs to be filtered out of the exhaust, sintered, and then reground. The efficiency penalty of reprocessing the fuel is about 0.1% - 1 kWh of reprocessing for every 1 MWh of generation.

[-] Delta_V@lemmy.world 2 points 1 day ago* (last edited 1 day ago)

The existing nuclear infrastructure has its own issues, like long term waste management. My understanding is that long lived isotopes can be burned as fuel in fast breeder reactors, and the waste from those is safe in 100 years. Every nuclear power plant having enough cooling pools for 100 years worth of spent fuel is a manageable problem. But I've read that somewhere in that cycle some pretty nasty stuff gets generated & if it were stolen it could be used to make a potent radiological weapon. I think that's why building the things has been a non-starter in USA - we've been in a cold Civil War for the last 161 years, and I think MAGA would do a nuclear terrorism if we gave them the opportunity.

But yeah, iron powder is a drop in replacement for coal in stationary, utility scale electrical generation.

Iron powder is easier to transport than hydrogen. Hydrogen needs high pressure, cryogenically cooled tanks. It turns any metal it touches brittle. And it boils off over time, losing some of its energy value during transport and storage.

Iron powder is safer and cheaper to transport than ammonia, which also needs a pressurized tank and would be a major disaster if it spilled. Reprocessing rust back into iron using hydrogen is also orders of magnitude more efficient than converting hydrogen into ammonia.

All iron powder needs for transport is a shipping container full of nitrogen gas, with a rubber gasket to keep it somewhat air tight. If it spills its just a pile of rocks.

And if the source of renewable energy is co-located with the electrolysis plant, the rust recharging plant, and the thermal power plant, the cycle's excess O2 from electrolysis and nitrogen gas production can be pumped into the burner of the power plant, increasing efficiency and eliminating nitric acid pollution.

11

...One of the challenges of clean energy is transporting and storing massive amounts of solar and wind power over long distances...

According to the new study, pulverized iron powder could act as a highly efficient, recyclable clean energy storage material...

The concept taps into a beautifully simple chemical loop. When iron powder is combusted, it releases intense heat and turns into iron oxide. In other words, it rusts. To reset it, scientists use green hydrogen generated from excess renewable energy to strip away the oxygen, reducing the rust back into pure iron powder. No carbon dioxide escapes into the atmosphere. The cycle simply repeats...

As it burns similarly to fossil fuels, energy giants wouldn’t need to rebuild their infrastructure from scratch...

The expensive components already in place, such as the steam cycles, massive turbines, heavy generators, and local grid connections, could be fully preserved...

[-] Delta_V@lemmy.world 2 points 5 days ago* (last edited 4 days ago)

That's true for older magnetorquers, because the Earth's magnetic field is smooth enough that the difference between field strength at the top and bottom of the satellite is insignificant.

With superconductors you can scale up the magnetic field strength enough to get a usable net linear force.

120
submitted 5 days ago by Delta_V@lemmy.world to c/space@mander.xyz

..."Once you have super-conducting technology available in space, you can then create very strong magnetic fields and you can use them for various use cases," he said. "You can accelerate things in space very fast or change the trajectory of a satellite completely without fuel."...

"When we go to space, we get hurt by radiation, and these superconducting magnets can create umbrellas of magnetic fields around the spacecraft to protect the interior," said Arshavsky. "So we can shield people in space from that radiation."...

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submitted 1 week ago by Delta_V@lemmy.world to c/space@mander.xyz

...a Yale-led team measured the internal motions of a faint, diffuse galaxy called NGC 1052-DF9 and found its stars moving too slowly to hide a normal dark matter halo. The galaxy joins two earlier oddballs, DF2 and DF4, and all three lie along the same narrow line of galaxies in the NGC 1052 field...

A few years ago the same group noticed that DF2 and DF4 were not alone. About a dozen faint galaxies in the field fall along a remarkably tight, straight trail, and follow-up work showed their velocities increase steadily along its length...

That geometry points to a specific and dramatic origin. In one leading idea, two gas-rich galaxies slammed into each other at high speed long ago. The dark matter of each passed straight through, because dark matter barely interacts with anything, while the ordinary gas piled up, shocked and compressed, and later collapsed into a string of small galaxies made almost entirely of normal matter...

...The finding is that DF9’s motion is consistent with its stars alone and inconsistent with a full dark matter halo. That is not the same as proving the halo is exactly zero. A modest amount of dark matter still fits inside the error bars; a normal amount does not...

The deeper reason astronomers care is almost the opposite of what the headline suggests. Finding galaxies without dark matter is, oddly, some of the better evidence that dark matter is real. If gravity simply behaved differently in faint galaxies, as some alternative theories propose, then every galaxy of a given size should show the same anomaly. Instead a few galaxies, all apparently born in the same collision, stand out from thousands of ordinary ones. Dark matter that can be left behind in a crash is dark matter that exists as a substance, not as a quirk of the equations...

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submitted 1 week ago by Delta_V@lemmy.world to c/space@mander.xyz

...After a long, challenging cruise phase with nine planetary flybys (one by Earth, two by Venus and six by Mercury), BepiColombo finally closed this chapter last Monday by permanently switching off its SEP thrusters...

Without any other source of propulsion, BepiColombo will follow a “ballistic” or free-falling trajectory as it initiates its first key arrival manoeuvre – MTM separation – on 3 September 2026.

After the MTM is ejected, the remaining spacecraft composite (MPO-Mio-MOSIF) will continue its planetary approach using MPO’s chemical propulsion system. This system will adjust the spacecraft’s trajectory ahead of the critical Mercury orbit insertion manoeuvre on 21 November, then guide it into Mio’s deployment orbit in early December before finally lowering MPO into its science orbit by March 2027...

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submitted 1 week ago by Delta_V@lemmy.world to c/space@mander.xyz

In 2025, astronomers reported one of the largest rotating structures ever found: a cosmic filament some 50 million light-years long, holding close to 300 galaxies, with many of them turning in step with the filament as a whole. The coordinated motion is difficult to reconcile with the way galaxies are thought to acquire their spin...

Galaxies are thought to get their spin early, through what is called tidal torque: as matter collapses under gravity, the uneven pull of its surroundings sets it turning. On that picture, a galaxy’s spin is shaped mostly by its own local patch of the universe, and there is no obvious reason for hundreds of galaxies, spread across tens of millions of light-years, to share a single coordinated rotation tied to the filament around them...

The question underneath is an old one, which is where galaxies get their angular momentum. This filament has not answered it, but it has handed the problem a large and awkward new clue.

18
submitted 1 week ago by Delta_V@lemmy.world to c/space@mander.xyz

...In May 2026, a team of researchers reported evidence for primordial black holes (PBHs) by spotting a short-lived flicker of light from a star in the Large Magellanic Cloud. They monitored millions of stars in this galaxy using DECam. They spotted one star that briefly brightened for less than an hour. They interpreted this as a gravitational microlensing event. Microlensing occurs when a tiny object passes in front of a star and its gravity briefly bends and magnifies the star's light like a lens.

Because the brightening was so short, they calculated the "lens" causing it must have had about the mass of the moon. This one-time, nonrepeating signal was interpreted as a microlensing event caused by a primordial black hole nicknamed "Phoebe."...

In this new study, Udalski and Mr.óz present an independent analysis of the same public DECam data, plus extra observations from 2020 and 2021 that the previous paper didn't include.

They found that the star brightened at least three separate times over the years—one of which was previously interpreted as a microlensing event. In addition, its average brightness also changed over time...

"This is not the first time that a variable star has been mistaken for a short-timescale microlensing event in high-cadence time-series observations of limited duration," the researchers note. Short-term monitoring lasting some days, they explain, simply isn't enough to tell the difference. Distinguishing a genuine one-time gravitational event from a star's natural flickering requires months or years of monitoring.

4
submitted 2 weeks ago* (last edited 2 weeks ago) by Delta_V@lemmy.world to c/Science@europe.pub

...In 2013, a team of anthropologists led by Lee Berger unearthed the remains of more than 20 small-bodied hominins (ancient relatives of humans), all 335,000 to 236,000 years old, from the Rising Star Cave System in South Africa. Excavations at Rising Star have sparked debate about whether these little hominins had all ended up in the caves by tragic accident, or whether they’d been carefully placed there by other members of their enigmatic species, dubbed Homo naledi.

Now there’s a plot twist that may speak to how the remains got there: All of the hominins in Rising Star are female, at least according to the proteins in their dental enamel...

There’s an ongoing debate about Neanderthal art and abstract thought despite a growing pile of evidence. And that sort of debate rises in intensity when the early hominins in question have brains as relatively small as Homo naledi’s, which is about the size of a chimpanzee’s.

“There is a divide in the field between those that think that humans evolved from cultural species that were before us, and those that believe that culture originated with modern humans,” says Hawks, “so they resist any claims of culture earlier unless they have some sort of extraordinary evidence.”...

“This is our first contact with a—and I think it’s important to repeat this—a non-human species. Their brains are not human brains,” says Berger. And he’s deeply concerned about how humanity navigates that first contact.

...no other hominin species, meaning none of the Australopithecines and not even Homo erectus, have presented us with such clear evidence that they tended to their dead and etched art or symbols on the cave walls nearby. In other words, Homo naledi might have thought and felt in ways that we have to recognize as on a level with our own cognition...

...He hopes the protein study will prompt anthropologists and Homo sapiens in general to seriously think about the ethics of digging up the graves of an intelligent and cultured but non-human species.

“It certainly will mean we have to stop digging hominins like dinosaurs,”...

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...The discovery expands how motors and actuation systems can be designed. Most electromagnetic motors today depend on magnets and copper coils. This new approach can create motion without magnets or rare earth metals, which could be valuable in a world where material resources are limited.

The design could also be lighter and simpler. Since the rotating component can be made from resin instead of metal, devices may become lighter and faster to respond. That could help in robotics, compact machines, and precision systems.

Because the motor does not depend on magnetic fields, it may also work well in places where magnetic noise causes problems, including medical equipment and data storage devices...

348
submitted 2 weeks ago by Delta_V@lemmy.world to c/space@mander.xyz

The discovery of all five nucleobases on Ryugu strengthens the idea that life’s molecular ingredients formed in space before reaching Earth.

A new study reports that samples from the asteroid Ryugu contain all five fundamental nucleobases, the molecular “letters” of life.

Tiny asteroid grains can preserve chemical clues about the ingredients that may have helped life emerge on Earth. The Ryugu material was returned from space in 2020 by the Japan Aerospace Exploration Agency’s (JAXA) Hayabusa2 mission.

In 2023, an international research team reported finding uracil, one of the nucleobases, in the Ryugu samples. Now, a study published on March 16, 2026, in Nature Astronomy by Japanese scientists has confirmed that all five nucleobases are present in the pristine asteroid material.

The finding suggests that these life related ingredients may have been common across the young Solar System...

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submitted 2 weeks ago by Delta_V@lemmy.world to c/Science@europe.pub

On a flat dry lakebed in Death Valley National Park, heavy rocks sit at the end of long grooves they have plowed across the mud. The trails run for tens of meters, some bending in sharp turns or doubling back, yet no one had ever watched a rock actually move. For more than sixty years the question of how they travel sat unanswered, the subject of guesses that ranged from hurricane-strength winds to floating sheets of ice.

In 2014 a research team published the first direct scientific observation of the rocks in motion, and the mechanism turned out to be far gentler than the leading theories. The stones glide when a thin sheet of ice, only three to six millimeters thick, covers a shallow winter pond, starts to melt in the late morning sun, and breaks into floating panels that a light wind nudges across the water. The ice shoves the rocks along at a walking pace of a few meters per minute...

2
submitted 3 weeks ago by Delta_V@lemmy.world to c/Science@europe.pub

Malaysian scientists have discovered a new species of parasitic fungus in Borneo's jungles that preys on "zombie fungi" known to infect insects before subjecting them to a gruesome death...

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submitted 3 weeks ago by Delta_V@lemmy.world to c/world@lemmy.world

The Lebanese Armed Forces on Monday urged people displaced from the south of the country by Israeli military operations there not to return to their homes and await further instructions, following Sunday's announcement of a memorandum of understanding that could bring an end to the U.S.-Israeli war with Iran.

"In light of recent developments in the region and with news circulating about reaching a ceasefire, the Army Command emphasizes the need for residents to postpone their return to the southern border villages and towns, and to adhere to the instructions of the deployed military units, in order to protect their safety from the danger of Israeli violations and attacks,"...

Israeli Defense Minister Israel Katz on Monday said that the Israel Defense Forces will not withdraw from areas it has seized in southern Lebanon, Syria and the Gaza Strip regardless of a deal with Iran.

[-] Delta_V@lemmy.world 84 points 7 months ago

Every once in a while, declare sausage. It confuses the hell out of your enemies.

--Rule of Acquisition #76

[-] Delta_V@lemmy.world 160 points 8 months ago

"I have never wished a man dead, but I have read some obituaries with great pleasure."

--Abraham Lincoln

[-] Delta_V@lemmy.world 74 points 8 months ago

The purchase price was historically low due to the libelous accusations of acetaminophen causing autism.

Investing in corruption pays off bigly when Republicans manage to ooze their way into office.

[-] Delta_V@lemmy.world 168 points 9 months ago* (last edited 9 months ago)
[-] Delta_V@lemmy.world 74 points 1 year ago

The eggs are from these flappy guys:

[-] Delta_V@lemmy.world 143 points 1 year ago* (last edited 1 year ago)

This is a Bash fork bomb, a malicious function definition that recursively calls itself:

:() — defines a function named : (yes, just a colon).

{ :|:& } — the function's body:

    :|: — pipes the output of the function into another call of itself, creating two processes each time.

    & — runs the call in the background, meaning it doesn’t wait for completion.

; — ends the function definition.

: — finally, this invokes the function once, starting the bomb.
[-] Delta_V@lemmy.world 81 points 1 year ago

lol, as if Harvard were liberal

they're infamously, thuggishly conservative

[-] Delta_V@lemmy.world 106 points 2 years ago

Ukrainian farmer: "How do I put this hunk of junk into Neutral so I can load it onto my trailer?" *starts an argument on War Thunder forums*

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Delta_V

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