In the comments of a recent article, the question came up as to where to find projects from the really smart kids the greybeards remember being in the 70s. In the case of [Will Dana] the answer is YouTube, where he’s done an excellent job of producing an ISS-tracking lamp, especially considering he’s younger than almost all of the station’s major components.*
There’s nothing ground-breaking here, and [Will] is honest enough to call out his inspiration in the video. Choosing to make a ground-track display with an off-the-shelf globe is a nice change from the pointing devices we’ve featured most recently. Inside the globe is a pair of stepper motors configured for alt/az control– which means the device must reset every orbit, since [Willis] didn’t have slip rings or a 360 degree stepper on hand. A pair of magnets couples the motion system inside the globe to the the 3D printed ISS model (with a lovely paintjob thanks to [Willis’s girlfriend]– who may or may be from Canada, but did show up in the video to banish your doubts as to her existence), letting it slide magically across the surface. (Skip to the end of the embedded video for a timelapse of the globe in action.) The lamp portion is provided by some LEDs in the base, which are touch-activated thanks to some conductive tape inside the 3D printed base.
It’s all controlled by an ESP32, which fetches the ISS position with a NASA API. Hopefully it doesn’t go the way of the sighting website, but if it does there’s more than enough horsepower to calculate the position from orbital parameters, and we are confident [Will] can figure out the code for that. That should be pretty easy compared to the homebrew relay computer or the animatronic sorting hat we featured from him last year.
Image of Sedna, taken by the Hubble Space telescope in 2004. (Credit: NASA)
While for most people Pluto is the most distant planet in the Solar System, things get a lot more fuzzy once you pass Neptune and enter the realm of trans-Neptunian objects (TNOs). Pluto is probably the most well-known of these, but there are at least a dozen more of such dwarf planets among the TNOs, including 90377 Sedna.
This obviously invites the notion of sending an exploration mission to Sedna, much as was done with Pluto and a range of other TNOs through the New Horizons spacecraft. How practical this would be is investigated in a recent study by [Elena Ancona] and colleagues.
The focus is here on advanced propulsion methods, including nuclear propulsion and solar sails. Although it’s definitely possible to use a similar mission profile as with the New Horizons mission, this would make it another long-duration mission. Rather than a decades-long mission, using a minimally-equipped solar sail spacecraft could knock this down to about seven years, whereas the proposed Direct Fusion Drive (DFD) could do this in ten, but with a much larger payload and the ability do an orbital insertion which would obviously get much more science done.
As for the motivation for a mission to Sedna, its highly eccentric orbit that takes it past the heliopause means that it spends relatively little time being exposed to the Sun’s rays, which should have left much of the surface material intact that was present during the early formation of the Solar System. With our explorations of the Solar System taking us ever further beyond the means of traditional means of space travel, a mission to Sedna might not only expand our horizons, but also provide a tantalizing way to bring much more of the Solar System including the Kuiper belt within easy reach.
As we watched the latest SpaceX Starship rocket test end in a spectacular explosion, we might have missed the news from Japan of a different rocket passing a successful test. We all know Honda as a car company but it seems they are in the rocket business too, and they successfully tested a reusable rocket. It’s an experimental 900 kg model that flew to a height of 300 m before returning itself to the pad, but it serves as a valuable test platform for Honda’s take on the technology.
It’s a research project as it stands, but it’s being developed with an eye towards future low-cost satellite launches rather than as a crew launch platform.As a news story though it’s of interest beyond its technology, because it’s too easy to miss news from the other side of the world when all eyes are looking at Texas. It’s the latest in a long line of interesting research projects from the company, and we hope that this time they resist the temptation to kill their creation rather than bring it to market.
We take it for granted that we almost always have cell service, no matter where you go around town. But there are places — the desert, the forest, or the ocean — where you might not have cell service. In addition, there are certain jobs where you must be able to make a call even if the cell towers are down, for example, after a hurricane. Recently, a combination of technological advancements has made it possible for your ordinary cell phone to connect to a satellite for at least some kind of service. But before that, you needed a satellite phone.
On TV and in movies, these are simple. You pull out your cell phone that has a bulkier-than-usual antenna, and you make a call. But the real-life version is quite different. While some satellite phones were connected to something like a ship, I’m going to consider a satellite phone, for the purpose of this post, to be a handheld device that can make calls.
History
Satellites have been relaying phone calls for a very long time. Early satellites carried voice transmissions in the late 1950s. But it would be 1979 before Inmarsat would provide MARISAT for phone calls from sea. It was clear that the cost of operating a truly global satellite phone system would be too high for any single country, but it would be a boon for ships at sea.
Inmarsat, started as a UN organization to create a satellite network for naval operations. It would grow to operate 15 satellites and become a private British-based company in 1998. However, by the late 1990s, there were competing companies like Thuraya, Iridium, and GlobalStar.
An IsatPhone-Pro (CC-BY-SA-3.0 by [Klaus Därr])The first commercial satellite phone call was in 1976. The oil platform “Deep Sea Explorer” had a call with Phillips Petroleum in Oklahoma from the coast of Madagascar. Keep in mind that these early systems were not what we think of as mobile phones. They were more like portable ground stations, often with large antennas.
For example, here was part of a press release for a 1989 satellite terminal:
…small enough to fit into a standard suitcase. The TCS-9200 satellite terminal weighs 70lb and can be used to send voice, facsimile and still photographs… The TCS-9200 starts at $53,000, while Inmarsat charges are $7 to $10 per minute.
Keep in mind, too, that in addition to the briefcase, you needed an antenna. If you were lucky, your antenna folded up and, when deployed, looked a lot like an upside-down umbrella.
However, Iridium launched specifically to bring a handheld satellite phone service to the market. The first call? In late 1998, U.S. Vice President Al Gore dialed Gilbert Grosvenor, the great-grandson of Alexander Graham Bell. The phones looked like very big “brick” phones with a very large antenna that swung out.
Of course, all of this was during the Cold War, so the USSR also had its own satellite systems: Volna and Morya, in addition to military satellites.
Location, Location, Location
The earliest satellites made one orbit of the Earth each day, which means they orbit at a very specific height. Higher orbits would cause the Earth to appear to move under the satellite, while lower orbits would have the satellite racing around the Earth.
That means that, from the ground, it looks like they never move. This gives reasonable coverage as long as you can “see” the satellite in the sky. However, it means you need better transmitters, receivers, and antennas.
This is how Inmarsat and Thuraya worked. Unless there is some special arrangement, a geosynchronous satellite only covers about 40% of the Earth.
Getting a satellite into a high orbit is challenging, and there are only so many “slots” at the exact orbit required to be geosynchronous available. That’s why other companies like Iridium and Globalstar wanted an alternative.
That alternative is to have satellites in lower orbits. It is easier to talk to them, and you can blanket the Earth. However, for full coverage of the globe, you need at least 40 or 50 satellites.
The system is also more complex. Each satellite is only overhead for a few minutes, so you have to switch between orbiting “cell towers” all the time. If there are enough satellites, it can be an advantage because you might get blocked from one satellite by, say, a mountain, and just pick up a different one instead.
Globalstar used 48 satellites, but couldn’t cover the poles. They eventually switched to a constellation of 24 satellites. Iridium, on the other hand, operates 66 satellites and claims to cover the entire globe. The satellites can beam signals to the Earth or each other.
The Problems
There are a variety of issues with most, if not all, satellite phones. First, geosynchronous satellites won’t work if you are too far North or South since the satellite will be so low, you’ll bump into things like trees and mountains. Of course, they don’t work if you are on the wrong side of the world, either, unless there is a network of them.
Getting a signal indoors is tricky. Sometimes, it is tricky outdoors, too. And this isn’t cheap. Prices vary, but soon after the release, phones started at around $1,300, and then you paid $7 a minute to talk. The geosynchronous satellites, in particular, are subject to getting blocked momentarily by just about anything. The same can happen if you have too few satellites in the sky above you.
Modern pricing is a bit harder to figure out because of all the different plans. However, expect to pay between $50 and $150 a month, plus per-minute charges ranging from $0.25 to $1.50 per minute. In general, networks with less coverage are cheaper than those that work everywhere. Text messages are extra. So, of course, is data.
If you want to see what it really looked like to use a 1990-era Iridium phone, check out [saveitforparts] video below.
If you prefer to see an older non-phone system, check him out with an even older Inmarsat station in this video:
Time series of O2 (blue) and VGADM (red). (Credit: Weijia Kuang, Science Advances, 2025)
In an Earth-sized take on the age-old ‘correlation or causality’ question, researchers have come across a fascinating match between Earth’s magnetic field and its oxygen levels since the Cambrian explosion, about 500 million years ago. The full results by [Weijia Kuang] et al. were published in Science Advances, where the authors speculate that this high correlation between the geomagnetic dipole and oxygen levels as recorded in the Earth’s geological mineral record may be indicative of the Earth’s geological processes affecting the evolution of lifeforms in its biosphere.
As with any such correlation, one has to entertain the notion that said correlation might be spurious or indirectly related before assuming a strong causal link. Here it is for example known already that the solar winds affect the Earth’s atmosphere and with it the geomagnetic field, as more intense solar winds increase the loss of oxygen into space, but this does not affect the strength of the geomagnetic field, just its shape. The question is thus whether there is a mechanism that would affect this field strength and consequently cause the loss of oxygen to the solar winds to spike.
Here the authors suggest that the Earth’s core dynamics – critical to the geomagnetic field – may play a major role, with conceivably the core-mantle interactions over the course of millions of years affecting it. As supercontinents like Pangea formed, broke up and partially reformed again, the impact of this material solidifying and melting could have been the underlying cause of these fluctuations in oxygen and magnetic field strength levels.
Although hard to say at this point in time, it may very well be that this correlation is causal, albeit as symptoms of activity of the Earth’s core and liquid mantle.
We like scale models here, but how small can you shrink the very large? If you’re [Frans], it’s pretty small indeed: his Micro Tellurium fits the orbit of the Earth on top of an ordinary pencil. While you’ll often see models of Earth, Moon and Sun’s orbital relationship called “Orrery”, that’s word should technically be reserved for models of the solar system, inclusive of at least the classical planets, like [Frans]’s Gentleman’s Orrery that recently graced these pages. When it’s just the Earth, Moon and Sun, it’s a Tellurium.
The whole thing is made out of brass, save for the ball-bearings for the Earth and Moon. Construction was done by a combination of manual milling and CNC machining, as you can see in the video below. It is a very elegant device, and almost functional: the Earth-Moon system rotates, simulating the orbit of the moon when you turn the ring to make the Earth orbit the sun. This is accomplished by carefully-constructed rods and a rubber O-ring.
Unfortunately, it seems [Franz] had to switch to a thicker axle than originally planned, so the tiny moon does not orbit Earth at the correct speed compared to the solar orbit: it’s about half what it ought to be. That’s unfortunate, but perhaps that’s the cost one pays when chasing smallness. It might be possible to fix in a future iteration, but right now [Franz] is happy with how the project turned out, and we can’t blame him; it’s a beautiful piece of machining.
It should be noted that there is likely no tellurium in this tellurium — the metal and the model share the same root, but are otherwise unrelated. We have featured hacks with that element, though.
Thanks to [Franz] for submitting this hack. Don’t forget: the tips line is always open, and we’re more than happy to hear you toot your own horn, or sing the praises of someone else’s work.
When we were kids, it was a rite of passage to read the newly arrived Edmund catalog and dream of building our own telescope. One of our friends lived near a University, and they even had a summer program that would help you measure your mirrors and ensure you had a successful build. But most of us never ground mirrors from glass blanks and did all the other arcane steps required to make a working telescope. However, [La3emedimension] wants to tempt us again with a 3D-printable telescope kit.
Before you fire up the 3D printer, be aware that PLA is not recommended, and, of course, you are going to need some extra parts. There is supposed to be a README with a bill of parts, but we didn’t see it. However, there is a support page in French and a Discord server, so we have no doubt it can be found.
It is possible to steal the optics from another telescope or, of course, buy new. You probably don’t want to grind your own mirrors, although good on you if you do! You can even buy the entire kit if you don’t want to print it and gather all the parts yourself.
The scope is made to be ultra-portable, and it looks like it would be a great travel scope. Let us know if you build one or a derivative.
This telescope looks much different than other builds we’ve seen. If you want to do it all old school, we’ve seen a great guide.
Where’s the best place for a datacenter? It’s an increasing problem as the AI buildup continues seemingly without pause. It’s not just a problem of NIMBYism; earthly power grids are having trouble coping, to say nothing of the demand for cooling water. Regulators and environmental groups alike are raising alarms about the impact that powering and cooling these massive AI datacenters will have on our planet.
While Sam Altman fantasizes about fusion power, one obvious response to those who say “think about the planet!” is to ask, “Well, what if we don’t put them on the planet?” Just as Gerald O’Niell asked over 50 years ago when our technology was merely industrial, the question remains:
“Is the surface of a planet really the right place for expanding technological civilization?”
O’Neill’s answer was a resounding “No.” The answer has not changed, even though our technology has. Generative AI is the latest and greatest technology on offer, but it turns out it may be the first one to make the productive jump to Earth Orbit. Indeed, it already has, but more on that later, because you’re probably scoffing at such a pie-in-the-sky idea.
There are three things needed for a datacenter: power, cooling, and connectivity. The people at companies like Starcloud, Inc, formally Lumen Orbit, make a good, solid case that all of these can be more easily met in orbit– one that includes hard numbers.
Sure, there’s also more radiation on orbit than here on earth, but our electronics turn out to be a lot more resilient than was once thought, as all the cell-phone cubesats have proven. Starcloud budgets only 1 kg of sheilding per kW of compute power in their whitepaper, as an example. If we can provide power, cooling, and connectivity, the radiation environment won’t be a showstopper.
Power
There’s a great big honkin’ fusion reactor already available for anyone to use to power their GPUs: the sun. Of course on Earth we have tricky things like weather, and the planet has an annoying habit of occluding the sun for half the day but there are no clouds in LEO. Depending on your choice of orbit, you do have that annoying 45 minutes of darkness– but a battery to run things for 45 minutes is not a big UPS, by professional standards. Besides, the sun-synchronous orbits are right there, just waiting for us to soak up that delicious, non-stop solar power.
Sun Synchronous Orbit, because nights are for squats. Image by Brandir via Wikimedia.
Sun-synchronous orbits (SSOs) are polar orbits that precess around the Earth once every sidereal year, so that they always maintain the same angle to the sun. For example, you might have an SSO that crosses the equator 12 times a day, each time at local 15:00, or 10:43, any other time set by the orbital parameters. With SSOs, you don’t have to worry about ever losing solar power to some silly, primitive, planet-bound concept like nighttime.
Without the atmosphere in the way, solar panels are also considerably more effective per unit area, something the Space Solar Power people have been pointing out since O’Neill’s day. The problem with Space Solar Power has always been the efficiencies and regulatory hurdles of beaming the power back to Earth– but if you use the power to train an AI model, and send the data down, that’s no longer an issue. Given that the 120 kW array on ISS has been trouble-free for decades now, we can consider it a solved problem. Sure, solar panels degrade, but the rate is in fractions of a percent per year, and it happens on Earth too. By the time solar panel replacement is likely to be the rest of the hardware is likely to be totally obsolete.
Cooling
This is where skepticism creeps in. After all, cooling is the greatest challenge with high performance computing hardware here on earth, and heat rejection is the great constraint of space operations. The “icy blackness of space” you see in popular culture is as realistic as warp drive; space is a thermos, and shedding heat is no trivial issue. It is also, from an engineering perspective, not a complex issue. We’ve been cooling spacecraft and satellites using radiators to shed heat via infrared emission for decades now. It’s pretty easy to calculate that if you have X watts of heat to reject at Y degrees, you will need a radiator of area Z. The Stephan-Boltzmann Law isn’t exactly rocket science.
Photons go out, liquid cools down. It might be rocket science, but it’s a fairly mature technology. (Image: EEATCS radiator deployment during ISS Flight 5A, NASA)
Even better, unlike on Earth where you have changeable things like seasons and heat waves, in a SSO you need only account for throttling– and if your data center is profitable, you won’t be doing much of that. So while you need a cooling system, it won’t be difficult to design. Liquid or two-phase cooling on server hardware? Not new. Plumbing cooling a loop to a radiator in the vacuum of space? That’s been part of satellite busses for years.
Aside from providing you with a stable thermal environment, the other advantage of an SSO is that if one chooses the dawn/dusk orbit along the terminator, while the solar panels always face the sun, the radiators can always face black space, letting them work to their optimal potential. This would also simplify the satellite bus, as no motion system would be required to keep the solar panels and radiators aligned into/out of the sun. Conceivably the whole thing could be stabilized by gravity gradient, minimizing the need to use reaction wheels.
Connectivity
One word: Starlink. That’s not to say that future data centers will necessarily be hooking into the Starlink network, but high-bandwidth operations on orbit are already proven, as long as you consider 100 gigabytes per second sufficient bandwidth. An advantage not often thought of for this sort of space-based communications is that the speed of light in a vacuum is about 31% faster than glass fibers, while the circumference of a low Earth orbit is much less than 31% greater than the circumference of the planet. That reduces ping times between elements of free-flying clusters or clusters and whatever communications satellite is overhead of the user. It is conceivable, but by no means a sure thing, that a user in the EU might have faster access to orbital data than they would to a data center in the US.
The Race
This hypothetical European might want to use European-owned servers. Well, the European Commission is on it; in the ASCEND study (Advanced Space Cloud for European Net zero Emission and Data sovereignty) you can tell from the title they put as much emphasis on keeping European data European as they do on the environmental aspects mentioned in the introduction. ASCEND imagines a 32-tonne, 800 kW data center lofted by a single super-heavy booster (sadly not Ariane 6), and proposes it could be ready by the 2030s. There’s no hint in this proposal that the ASCEND Consortium or the EC would be willing to stop at one, either. European efforts have already put AI in orbit, with missions like PhiSat2 using on-board AI image processing for Earth observation.
You know Italians were involved because it’s so stylish. No other proposal has that honeycomb aesthetic for their busy AI bees. Image ASCEND.
AWS Snowcone after ISS delivery. The future is here and it’s wrapped in Kapton. (Image NASA)
There are other American companies chasing venture capital for this purpose, like Google-founder-backed Relativity Space or the wonderfully-named Starcloud mentioned above. Starcloud’s whitepaper is incredibly ambitious, talking about building an up to 5 GW cluster whose double-sided solar/radiator array would be by far the largest object ever built in orbit at 4 km by 4 km. (Only a few orders of magnitude bigger than ISS. Not big deal.) At least it is a modular plan, that could be built up over time, and they are planning to start with a smaller standalone proof-of-concept, Starcloud-2, in 2026.
You can’t accuse Starcloud of thinking small. (Image Starcloud via Youtube.)A closeup of one of the twelve “Stars” in the Three Body Computing Constellation. This times 2,800. Image ADA Space.
Once they get up there, the American and European AIs are are going to find someone else has already claimed the high ground, and that that someone else speaks Chinese. A startup called ADA Space launched 12 satellites in May 2025 to begin building out the world’s first orbital supercomputer, called the Three Body Computing Constellation. (You can’t help but love the poetry of Chinese naming conventions.)
Unlike the American startups, they aren’t shy about its capabilities: 100 Gb/s optical datalinks, with the most powerful satellite in the constellation capable of 744 trillion operations per second. (TOPS, not FLOPS. FLOPS specifically refers to floating point operations, whereas TOPS could be any operation but usually refers to operations on 8-bit integers.)
For comparison, Microsoft requires an “AI PC” like the copilot laptops to have 40 TOPS of AI-crunching capacity. The 12 satellites must not be identical, as the constellation together has a quoted capability of 5 POPS (peta-operations per second), and a storage capacity of 30 TB. That’s seems pretty reasonable for a proof-of-concept. You don’t get a sense of the ambition behind it until you hear that these 12 are just the first wave of a planned 2,800 satellites. Now that’s what I’d call a supercluster!
A man can dream, can’t he? Image NASA.
High-performance computing in space? It’s no AI hallucination, it’s already here. There is a network forming in the sky. A sky-net, if you will, and I for one welcome our future AI overlords. They already have the high ground, so there’s no point fighting now. Hopefully this datacenter build-out will just be the first step on the road Gerry O’Neill and his students envisioned all those years ago: a road that ends with Earth’s surface as parkland, and civilization growing onwards and upwards. Ad astra per AI? There are worse futures.
If you were alive when 2001: A Space Odyssey was in theaters, you might have thought it didn’t really go far enough. After all, in 1958, the US launched its first satellite. The first US astronaut went up in 1961. Eight years later, Armstrong put a boot on the moon’s surface. That was a lot of progress for 11 years. The movie came out in 1968, so what would happen in 33 years? Turns out, not as much as you would have guessed back then. [The History Guy] takes us through a trip of what could have been if progress had marched on after those first few moon landings. You can watch the video below.
The story picks up way before NASA. Each of the US military branches felt like it should take the lead on space technology. Sputnik changed everything and spawned both ARPA and NASA. The Air Force, though, had an entire space program in development, and many of the astronauts for that program became NASA astronauts.
The Army also had its own stymied space program. They eventually decided it would be strategic to develop an Army base on the moon for about $6 billion. The base would be a large titanium cylinder buried on the moon that would house 12 people.
The base called for forty launches in a single year before sending astronauts, and then a stunning 150 Saturn V launches to supply building materials for the base. Certainly ambitious and probably overly ambitious, in retrospect.
There were other moon base plans. Most languished with little support or interest. The death knell, though, was the 1967 Outer Space Treaty, which forbids military bases on the moon.
While we’d love to visit a moon base, we are fine with it not being militarized. We also want our jet packs.
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