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Hackaday Links: August 13, 2023

Remember that time when the entire physics community dropped what it was doing to replicate the extraordinary claim that a room-temperature semiconductor had been discovered? We sure do, and if it seems like it was just yesterday, it’s probably because it pretty much was. The news of LK-99, a copper-modified lead apatite compound, hit at the end of July; now, barely three weeks later, comes news that not only is LK-99 not a superconductor, but that its resistivity at room temperature is about a billion times higher than copper. For anyone who rode the “cold fusion” hype train back in the late 1980s, LK-99 had a bit of code smell on it from the start. We figured we’d sit back and let science do what science does, and sure enough, the extraordinary claim seems not to be able to muster the kind of extraordinary evidence it needs to support it — with the significant caveat that a lot of the debunking papers –and indeed the original paper on LK-99 — seem still to be just preprints, and have not been peer-reviewed yet.

So what does all this mean? Sadly, probably not much. Despite the overwrought popular media coverage, a true room-temperature and pressure superconductor was probably not going to save the world, at least not right away. The indispensable Asianometry channel on YouTube did a great video on this. As always, his focus is on the semiconductor industry, so his analysis has to be viewed through that lens. He argues that room-temperature superconductors wouldn’t make much difference in semiconductors because the place where they’d most likely be employed, the interconnects on chips, will still have inductance and capacitance even if their resistance is zero. That doesn’t mean room-temperature superconductors wouldn’t be a great thing to have, of course; seems like they’d be revolutionary for power transmission if nothing else. But not so much for semiconductors, and certainly not today.

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See Satellites In Broad Daylight With This Sky-Mapping Dish Antenna

If you look up at the night sky in a dark enough place, with enough patience you’re almost sure to see a satellite cross the sky. It’s pretty cool to think you’re watching light reflect off a hunk of metal zipping around the Earth fast enough to never hit it. Unfortunately, it doesn’t work during the daylight hours, and you really only get to see satellites in low orbits.

Thankfully, there’s a trick that allows you to see satellites any time of day, even the ones in geosynchronous orbits — you just need to look using microwaves. That’s what [Gabe] at [saveitforparts] did with a repurposed portable satellite dish, the kind that people who really don’t like being without their satellite TV programming when they’re away from home buy and quickly sell when they realize that toting a satellite dish around is both expensive and embarrassing. They can be had for a song, and contain pretty much everything needed for satellite comms in one package: a small dish on a motorized altazimuth mount, a low-noise block amplifier (LNB), and a single-board computer that exposes a Linux shell.

After figuring out how to command the dish to specific coordinates and read the signal strength of the received transponder signals, [Gabe] was able to cobble together a Python program to automate the task. The data from these sweeps of the sky resulted in heat maps that showed a clear arc of geosynchronous satellites across the southern sky. It’s quite similar to something that [Justin] from Thought Emporium did a while back, albeit in a much more compact and portable package. The video below has full details.

[Gabe] also tried turning the dish away from the satellites and seeing what his house looks like bathed in microwaves reflected from the satellite constellation, which worked surprisingly well — well enough that we’ll be trawling the secondary market for one of these dishes; they look like a ton of fun.

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Space Age Road Rage: Right Of Way Above The Karman Line

On a dark night in 2006 I was bicycle commuting to my office, oblivious to the countless man made objects orbiting in the sky above me at thousands of miles per hour. My attention was instead focused on a northbound car speeding through a freeway underpass at dozens of miles per hour, oblivious to my southbound headlamp. The car swerved into the left turn lane to get to the freeway on-ramp. The problem? I was only a few feet from crossing the entrance to that very on-ramp! As the car rushed through their left turn I was presented with a split second decision: slow, and possibly stop in the middle of the on-ramp, or just go for it and hope for the best.

A graphic depicting a dawdling bicycle rider about to be in the way of a speeding car driver
In Blue: Terrified cyclist. In Red: A speeding car careening around a corner without slowing down.

By law I had the right of way. But this was no time to start discussing right of way with the driver of the vehicle that threatened to turn me into a dark spot on the road. I followed my gut instinct, and my legs burned in compliance as I sped across that on-ramp entrance with all my might. The oncoming car missed my rear wheel by mere feet! What could have ended in disaster and possibly even death had resulted in a near miss.

Terrestrial vehicles generally have laws and regulations that specify and enforce proper behavior. I had every right to expect the oncoming car be observant of their surroundings or to at least slow to a normal speed before making that turn. In contrast, traffic control in Earth orbit conjures up thoughts of bargain-crazed shoppers packed into a big box store on Black Friday.

So is spacecraft traffic in orbit really a free-for-all? If there were stringent rules, how can they be enforced? Before we explore the answers to those questions, let’s examine the problem we’re here to discuss: stuff in space running into other stuff in space.

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Window In The Skies: Why Everyone Is Going To Mars This Month

Mars may not be the kind of place to raise your kids, but chances are that one day [Elton John]’s famous lyrics will be wrong about there being no one there to raise them. For now, however, we have probes, orbiters, and landers. Mars missions are going strong this year, with three nations about to launch their rockets towards the Red Planet: the United States sending their Perseverance rover, China’s Tianwen-1 mission, and the United Arab Emirates sending their Hope orbiter.

As all of this is planned to happen still within the month of July, it almost gives the impression of a new era of wild space races where everyone tries to be first. Sure, some egos will certainly be boosted here, but the reason for this increased run within such a short time frame has a simple explanation: Mars will be right around the corner later this year — relatively speaking — providing an ideal opportunity to travel there right now.

In fact, this year is as good as it gets for quite a while. The next time the circumstances will be (almost) as favorable as this year is going to be in 2033, so it’s understandable that space agencies are eager to not miss out on this chance. Not that Mars missions couldn’t be accomplished in the next 13 years — after all, several endeavors are already in the wings for 2022, including the delayed Rosalind Franklin rover launch. It’s just that the circumstances won’t be as ideal.

But what exactly does that mean, and why is that? What makes July 2020 so special? And what’s everyone doing up there anyway? Well, let’s find out!

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Don’t Wait, You Need To See Comet NEOWISE Right Now

By now you’ve heard of NEOWISE, the most spectacular comet to visit our little corner of the galaxy since Hale-Bopp passed through over 20 years ago. But we’re willing to bet you haven’t actually seen it with your own eyes. That’s because up until now, the only way to view this interstellar traveler was to wake up in the pre-dawn hours; an especially difficult requirement considering a large chunk of the population has gotten used to sleeping-in over the last few months.

But things are about to change as NEOWISE begins a new phase of its trip through our celestial neck of the woods. Having come to within 44.5 million km (27.7 million miles) of the sun on July 3rd, the comet is now making its way back out of our solar system. Thanks to the complex dance of the heavens, that means that observers in the Northern Hemisphere will now be able to see NEOWISE in the evening sky just above the horizon.

NEOWISE is on a kind of “up and over” trajectory compared to the orbital paths of the planets. Get a better feel for it with JPL’s interactive solar dynamics tool.

While NEOWISE might be beating a hasty retreat from Sol right now, the comet it actually getting closer to us in the process. On July 22nd it will reach perigee, that is, the point in its orbit closest to Earth. On that evening the comet will be approximately 103 million km (64 million miles) away. Not exactly a stone’s throw, but pretty close in astronomical terms. The comet will appear to be getting higher in the sky as it approaches Earth, and should be visible with the naked eye between 10 and 20 degrees above the northern horizon.

Most estimates say that NEOWISE should remain visible until at least the middle of August, though it will be dimming rapidly. After that, you’re going to have to wait awhile for a repeat showing. Given the orbit of this particular comet, it won’t come around our way again for approximately 6,800 years, give or take a few lifetimes.

NASA will be hosting a NEOWISE live stream tomorrow afternoon where researchers will answer questions about this once in a lifetime celestial event, though we think you’ll get a lot more out of it if you just go outside and look up.

Northrop Grumman Tests Space Tow Truck

In the early days, satellites didn’t stick around for very long. After it was launched by the Soviet Union in 1957, it only took about three months for Sputnik 1 to renter the atmosphere and burn up. But the constant drive to push ever further into space meant that soon satellites would remain in orbit for years at a time. Not that they always functioned for that long; America’s Explorer 1 remained in orbit for more than twelve years, but its batteries died after just four months.

Of course back then, nobody was too worried about that sort of thing. When you can count the number of spacecraft in Earth orbit on one hand, what does it matter if one of them stays up there for more than a decade? The chances of a collision were so low as to essentially be impossible, and if the satellite was dead and wasn’t interfering with communication to its functional peers, all the better.

The likelihood of a collision steadily increased over the years as more and more spacecraft were launched, but the cavalier approach to space stewardship continued more or less unchanged into the modern era. In fact, it might have endured a few more decades if companies like SpaceX weren’t planning on mega-constellations comprised of thousands of individual satellites. Concerned over jamming up valuable near-Earth orbits with so much “space junk”, modern satellites are increasingly being designed with automatic disposal systems that help make sure they are safely deorbited even in the event of a system failure.

That’s good news for the future, but it doesn’t help us with the current situation. Thousands of satellites are in orbit above the planet, and they’ll need to be dealt with in the coming years. The good news is that many of them are at a low enough altitude that they’ll burn up on their own eventually, and methods are being developed to speed up the process should it be necessary to hasten their demise.

Unfortunately, the situation is slightly more complex with communications satellites in geosynchronous orbits. At an altitude of 35,786 kilometers (22,236 miles), deorbiting these spacecraft simply isn’t practical. It’s actually far easier to maneuver them farther out into space where they’ll never return. But what if the satellite fails or runs out of propellant before the decision to retire it can be made?

That’s precisely the sort of scenario the Mission Extension Vehicle (MEV) was developed for, and after a historic real-world test in February, it looks like this “Space Tow Truck” might be exactly what we need to make sure invaluable geosynchronous orbits are protected in the coming decades.

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Russia’s Newest Weather Satellite May Have Been Killed By Space Junk

For humans and satellites alike, making a living in space is hard. First, there’s the problem of surviving the brief but energetic and failure-prone ride there, after which you get to alternately roast and freeze as you zip around the planet at 20 times the speed of sound. The latter fact is made all the more dangerous by the swarm of space debris, both natural and man-made, that whizzes away up there along with you, waiting to cause an accident.

One such accident has apparently led to the early demise of a Russian weather satellite. Just a few months after launch, Meteor-M 2-2 suffered a sudden orbital anomaly (link to Russian story; English translation). Analysis of the data makes it pretty clear what happened: the satellite was struck by something, and despite some ground-controller heroics which appear to have stabilized the spacecraft, the odds are that Meteor-M 2-2 will eventually succumb to its wounds.

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