If you’re in motorsport, or maritime, or mining fields, you can always call on a technician to come down and fix something when it’s broken. You can lay hands on the parts, reconfigure things, make repairs, and get something working again. In space, that’s seldom possible. If you’re lucky enough to have a manned mission, you might be able to make some running repairs; if you’re working with an unmanned robot, probe, or satellite, your potions are altogether more limited. If you can’t find a fix, it’s game over—a particularly brutal result when huge budgets and years of work are on the line.

Janelle Wellons came down to Hackaday Europe to talk about space. More particularly, the engineering and debugging operations that keep all sorts of space programs alive. Her talk dives into some of the creative solutions engineers have had to come up with to save million-dollar missions from becoming unrecoverable boondoggles.

Janelle came down to Hackaday Europe to talk about space, because she lives and breathes it. An experienced aerospace engineer, she’s worked at NASA JPL and iSpace, contributing to the success of missions taking place far from our humble globe. She drew on that experience to talk through what it takes to keep a mission on the rails when things go a little sideways, which happens in space, just as it does anywhere else.

A fantastic example of that, retold in her talk, is the Galileo mission. It was built to travel far across the solar system, eventually winding up at Jupiter to study the Red Giant and its moons.  The probe was engineered with a pair of communication systems—a low-gain antenna for vital signs and management, and a high-gain antenna for sending science data and images back to Earth. The high-gain antenna was key to the mission, capable of offering 10,000 times the bandwidth of the low-gain antenna.

Tragically, though, the high-gain antenna never got to play its starring role. It didn’t deploy properly after launch, and that left NASA with a probe capable of capturing all this fantastic science data, but no way to send it home at a reasonable data rate. Janelle steps through the multiple hacks that make the most of the communication link with the low-gain antenna. NASA engineers whipped up compression algorithms for images and science data, and figured out how to array several Deep Space Network antennas for better signal. This netted an effective data transfer rate of 1,000 bits/second with the low gain antenna. It was still a far cry from the 134 kilobits per second that should have been possible with the high-gain antenna, but a huge leap forward from the 8-16 bits originally possible with the low-gain rig. Ultimately, it saved the mission, allowing the capture of mountains of scientific data on the largest planet in the solar system.

“NASA Astronaut Christina Cook is also working through troubleshooting steps of the waste management system that’s aboard the Integrity spacecraft.” – Ground control, Artemis II mission, 2026

Another great story told by Janelle concerned the Artemis II mission. The lunar flyby was part of NASA’s efforts to eventually return to the Moon itself, and was notable for debuting some special new hardware—the toilet. Unlike previous visits to the moon as part of the Apollo program, Artemis astronauts travel in luxury, with a proper commode built to handle the specific requirements of the zero-gravity space environment. Unfortunately, though, this new hardware had plenty of teething problems.

Early attempts to repair the system involved attempting to reprime the toilet’s pump by adding water to the system. It wasn’t long before the toilet threw another error, though. On the short-duration Artemis II mission, the toilet was set up to vent urine to space. Only, venting wasn’t working—with the suspicion being that the vent pipes had frozen over. The trick to solve this was simple—turning the spacecraft to face the vents towards the sun, so as to heat them enough to melt the blockage. Janelle also notes that during the multiple periods the toilet was down, the astronauts had to rely on alternative means of passing waste—showing a slide of the “collapsible contingency urinals” that did the job.

There’s also a great look at Perseverance’s twin, which lives here on Earth. Janelle has been down to the Mars yard at NASA’s Jet Propulsion Laboratory, where engineers, in her words—”test before you do.” The problem is, when you’re driving a robot on a foreign planet, you can’t just send someone over to repair a broken wheel or flip it back up if it tips over. Thus, many maneuvers and operations are rehearsed in the Mars yard with the twin of Perseverance, running it over recreated obstacles to determine a safe plan of attack.

After the Orion capsule of the Artemis I lunar mission returned to Earth, it was found that massive chunks of its heatshield had been ripped off, posing a serious risk to any future missions. In a recent video in which [polymatt] takes a break from repairing old laptop shells and the like, he tries to recreate the Orion’s heatshield using a variety of methods and materials.

For this test a number of samples were created, each using the same kind of segmented structure as the larger Orion heatshield. The filler was created from the published materials for the heat shield by NASA, requiring just serious mixing.

The resulting samples were then cured with thermocouples inserted, before they got blasted with the heat from a propane torch, trying to simulate the various re-entry patterns.

Perhaps unsurprisingly, the results matched the findings by NASA for why the Orion’s heat shield had failed, being the build-up of gases due to the sustained pyrolysis processes that eventually fractured the material. Despite some experimental flaws that injected residual heat from the copper structure, this still seems to be a pretty good setup to test ablative heat shields in DIY lab conditions.

Launched in 1976, LAGEOS-1 (LAser GEOdynamic Satellite) is unusual in that it contains no instrumentation, no electronics, no power supply, and no means of propulsion. It’s spherical, weighs just under 407 kg, and looks a bit like a disco ball. It may not be accurate to say it does nothing, but unlike most satellites its role is entirely passive. It’s also one of the oldest scientific satellites still in service.

The lens-like objects covering the surface of LAGEOS-1 are corner cube retroreflectors, which have the nifty effect of always reflecting incident light right back towards its source.

Ground stations fire short laser pulses at it and measure the time it takes for the light to return, a form of time-of-flight ranging. Since LAGEOS-1’s orbit is highly stable, it provides a reliable reference point for measuring even tiny changes in the Earth itself. The size, shape, rotation, and more of our planet can be measured as a result. LAGEOS data (LAGEOS-2 was launched in 1992) has also been used in tests of general relativity.

Its orbit and construction were deliberately chosen so that atmospheric drag and other disturbances would be minimal. The simple, maintenance-free design combined with an extraordinarily stable orbit means LAGEOS is expected to circle our world for millions of years to come.

LAGEOS-1 also contains a message to the future in the form of two identical plaques prepared by Dr. Carl Sagan just in case there’s anyone around to find it some day. Check out the short 1975 video from NASA, embedded just below.

As easy as the Sun is to observe, it’s simultaneously very hard to study due to how extreme the conditions are, even on the surface of a rather unassuming star. One of these study topics is the interaction between the Sun’s plasma and magnetic field, as this drives much of the dynamism of the Sun’s surface layer (i.e., the photosphere). Recent observations by the 4-meter solar telescope in Hawaii have now led to interesting new findings, as detailed in a paper in Nature by [David Kuridze] et al.

Despite popular portrayal, this photosphere is not a boiling liquid, but rather pockets of plasma at various temperatures. The plasma moves within the magnetic field and convective movements that create the ‘boiling’ pattern, which gives the illusion of a boiling liquid surface.

Within this photosphere, [Kuridze] et al. were able to observe Kelvin-Helmholtz instabilities, which are fluid instabilities caused by velocity shearing in either a continuous fluid or due to a velocity difference between two fluids. This is also observed in clouds in Earth’s atmosphere, where they cause the billowing effect, somewhat similar to watching a boiling liquid.

In a MURaM simulation (see heading image), these findings were confirmed, showing how these instabilities drive the transport of plasma in the Sun’s photosphere.

The history of European space exploration is a long and distinguished one, with many decades and whole families of launch vehicles. It might therefore come as a surprise that despite all this, it’s taken until 2026 for a European rocket to be launched into orbit from European soil rather than from somewhere close to the Equator. The German company Isar Aerospace launched one of their Spectrum rockets from Andøya Space in Norway and deployed its CubeSat payloads to orbit.

The five satellites were a selection of projects from the German space agency’s Microlauncher Competition, which offers the chance of a launch to start-ups and educational institutions. The press release doesn’t name them, but Wikipedia has the following list: TriSat-S (University of Maribor and SkyLabs); FramSat-1 (NTNU SpaceTeam); Sat1 (TU Wien Space Team); CyBEEsat (TU Berlin); Platform 6 (EnduroSat) and Let It Go (experiment, Dcubed).[46].

Interestingly, the company is also working on a space launch facility in Nova Scotia, Canada, to gain access to lower inclination orbits and to provide Canadians with their own launch capability. More is evidently yet to come.

We’ve mentioned Isar before, when we reported on the building of the spaceport.

Yesterday, Isar Aerospace secured its place in the history books when the upper stage of their Spectrum rocket put a payload of CubeSats into low Earth orbit (LEO). Not only does this make them the first European company to achieve such a feat, but it also marks the first time a booster departing from continental Europe has reached orbit. Not bad for a second attempt.

Standing 28 meters (92 feet) tall, the two-stage Spectrum rocket is just shy of half the size of the SpaceX Falcon 9 and designed to put a maximum of 1,000 kilograms (2,200 pounds) into LEO and 700 kg (1,500 lb) into the Sun-synchronous orbits used by Earth observation satellites. That puts its performance considerably ahead of other commercial launchers such as Rocket Lab’s Electron. Although the booster is not reusable, Isar Aerospace has stated they’re targeting a respectable launch cost of €10,000 ($11,700) per kilogram. The German company notes there are several more Spectrum vehicles currently in production, and when their new factory is operational, they’ll have the capacity to produce up to 40 of them each year.

In other European space news, BepiColombo has now entered what the European Space Agency (ESA) is calling the “arrival phase” of its nearly decade-long journey to Mercury. On Thursday, the spacecraft jettisoned its ion propulsion module as it had achieved the necessary trajectory and velocity to be captured by the planet’s gravitational field when it swoops by in November.

Launched in 2018, the BepiColombo mission is actually carrying two separate craft: the ESA’s Mercury Planetary Orbiter and the Mercury Magnetospheric Orbiter from Japan. After the two separate from each other in December, they will operate independently to study their respective aspects of the solar system’s innermost planet for the next year, although, as is often the case for missions like this, an extension is always possible if things are still going well at that point.

On the subject of hardware outliving its original design lifetime, an active community of hackers has done a fantastic job of keeping the Spotify Car Thing up and running after the company officially pulled the plug on it just two years after its 2022 release. They’ve got a full Linux distribution running on it featuring a slick UI that can launch apps, check the weather, tap into Home Assistant, and of course, play music. The community is currently running a contest with cash prizes to spur on development of new open source software for the liberated Car Thing, and we’re eager to see what comes of it.

Speaking of keeping things open, the Free Software Foundation (FSF) has joined Bluesky — but they aren’t exactly thrilled with it. Being federated and largely comprised of free and open-source software, the FSF admits that Bluesky is the lesser evil when compared to something like X or Facebook. But they still can’t recommend others join the service, as the actual signup process requires your browser to run non-free JavaScript code.

One may wonder why the FSF would join Bluesky if they can’t recommend the service to others, and the answer is simply because they want to get the word out to a wider audience. While the FSF already operates an account on Mastodon, there’s a good chance that anyone who’s willingly regularly using said platform doesn’t need any additional convincing when it comes to the evils of proprietary software.

This is as good a time as any to point out that Hackaday is on Bluesky and Mastodon as well, and unlike the FSF, we’re also on Facebook, although the automatic sharing of new posts hasn’t worked for quite some time and honestly we can’t be bothered to figure out why. For our readers with a particular aversion to grass, we’ve even got an official IRC channel on libera.chat where you and nearly 50 others can feel superior to the thousands of immoral heathens that have joined our Discord server.

Finally, it’s been 50 years since the introduction of the ColorChecker — that little card with 24 blocks of colors that’s placed in the frame of a picture or video to provide a visual reference point. In honor of the milestone, Calibrite has put together a timeline that walks you through its history, starting with its inception in the 1976 paper “A Color-Rendition Chart” by C.S. McCamy, H. Marcus, and J.G. Davidson and running up to how the handy tool evolved for the digital age.

There are plenty of facts and trivia about the ColorChecker that you can bring up the next time you want to impress a photographer, and we especially appreciated the breakdown of what each of the original 24 colors was meant to represent.

See something interesting that you think would be a good fit for our weekly Links column? Drop us a line; we’d love to hear about it.

Although some would argue that the hexagon is the bestagon, astronomers have discovered that Saturn appears to favor the ten-sided decagon on its south pole. This comes as its south pole has recently been confirmed to show a pattern that’s oddly ten-sided, per a recent research article by [Agustín Sánchez-Lavega] et al. in Science Advances.

Because Saturn is a gas giant, this naturally isn’t some gigantic planet-sized rock formation, but rather an interesting wave phenomenon in this massive gas bubble. The hexagon shape on its north pole had been known about for a while already, so it is perhaps not too surprising to find something similar on its south pole.

These shapes are generally the result of standing waves within a polar vortex, through the interaction of waves in Saturn’s atmosphere. For the north pole hexagon, the formation is driven by an intense eastward jet, but no similar wave had been reported for the planet’s south pole.

While in this paper a decagon shape is identified based on multiple observations, they postulate that it’s due to a meandering wave in the area rather than a jet as at the other pole. This clearly doesn’t make this wave pattern as obvious as the one at the north pole, but it provides another fascinating insight into fluid dynamics scaled up to a planetary gas giant.

The Universe is a large place, yet despite it being mostly empty space, there are still a lot of things to find and catalogue. This includes mildly terrifying things like supermassive black holes (SMBHs), one of the study subjects of the Sloan Digital Sky Survey (SDSS) project. In their 20th data release of the fifth all-sky survey (SDSS-V), the results of the Black Hole Mapper (BHM) program provides a lot of new insights into these SMBHs.

For a good primer on the SDSS’s ongoing survey, you can read this paper by [Kollmeier] et al. from 2017 in which this fifth survey and its three programs, including the BHM, are explained. This comes after four previous phases of the SDSS, all of them focusing on multispectral imaging and spectroscopic redshift survey with the 2.5 m Apache Point Observatory (APO) in New Mexico.

With SDSS-V a second 2.5 m observatory at Las Campanas (LCO) was added, with both observatories combined able to observe the entire sky, not just as static images, but also any changes over time. While these observations are in the near-infrared, combined with the data from other observatories this gives us probably one of the most comprehensive maps of the Milky Way and everything therein, including black holes.

This 20th data release gives us one of the clearest glimpses yet at the formation, growth and behavior of SMBHs and similar objects over time. A big part of this achievement are the automatic positioning robots at the observatories that handle the fiber optics that feed spectrographs, enabling faster and more accurate observations.

Last time we found out the idea of space stations is surprisingly old. By the 1950s, everyone knew we’d be working in beautiful space stations that rotated like a wheel to give us the illusion of gravity. Of course, that didn’t happen. But we did get some practical space stations, even before the current crop. The road to get there, though, was predictably bumpy.

Convair: From TASSEL to MARS

Convair had been studying multi-person orbital stations under Krafft Ehricke since the late 1950s. One result was TASSEL, an acronym for the Three Astronaut Space System Experimental Laboratory. Proposed in 1960, TASSEL was a three-man laboratory intended for an Atlas-Centaur launch into a roughly 200-nautical-mile orbit and missions lasting two or three weeks.

Around the same time, the Air Force asked contractors for proposals for a Military Test Space Station, or MTSS. Convair was one of five companies selected for the study in 1960. The surviving record suggests that Convair’s TASSEL work fed directly into its MTSS proposal.

Then Convair did something unusual for an era overflowing with beautiful paintings of spacecraft that never existed: they built theirs. Well, sort of.

During late 1960 and early 1961, the company constructed a full-scale ground mockup called the Manned Astronomical Research Station, or MARS. The station itself was about ten feet in diameter and fourteen feet high, with two floors for working, cooking, housekeeping, and sanitary facilities. A Mercury-like reentry capsule beneath it brought the whole assembly to about 28 feet tall. You can see a contemporary video about the program below. There’s also a cache of photos and a post by [The Space Review] explaining it all.

MARS obviously wasn’t going to orbit, but that wasn’t the point. Engineers could use it to work on the less photogenic parts of putting people in orbit: life support, oxygen consumption, water regeneration, contaminant monitoring, controls, displays, and simply discovering whether people and equipment actually fit where the drawings said they would. Crews later spent as long as 30 hours inside the mockup.

Exactly where MARS fits among Convair’s various proposals is still being pieced together. Archival evidence indicates that it grew out of TASSEL and closely overlapped Convair’s submission for the Air Force MTSS program. Photographs in the San Diego Air and Space Museum archive are even identified as “MTSS/MARS.” Whatever name was on the proposal of the week, by 1961 Convair had progressed from drawing space stations to building a high-fidelity example on the ground.

Olympus and MOL

NASA wasn’t far behind. In 1962, Edward Olling at the Manned Spacecraft Center proposed Project Olympus. It would have been an 18-person station intended for launch around 1966 or 1967. It wasn’t the classic doughnut. Instead, three long arms extended from a large central hub, and rotation would provide different artificial-gravity levels at different distances from the center. The station would orbit about 300 nautical miles above Earth.

This is especially interesting because Olympus wasn’t a far-future colony study. It was being considered while Mercury was still flying. Then President Kennedy gave NASA a somewhat more pressing assignment involving the Moon.
Olympus joined the large pile of spacecraft that looked great in presentations.

The U.S. Air Force had another station that got considerably closer to hardware: the Manned Orbiting Laboratory, or MOL. Approved in 1965, MOL would have put two military astronauts into a polar-orbiting station attached to a modified Gemini spacecraft (Gemini B). Its actual classified purpose was high-resolution reconnaissance. You can see some silent footage of some of the hardware in the video below.

They selected astronauts. They built hardware. They modified a Gemini capsule with the unnerving idea of putting a hatch through its heat shield so the crew could crawl into the laboratory behind it. MOL was canceled in 1969 without a crewed station ever flying.

Meanwhile, docking — one of the basic tricks required to make stations useful — was becoming real.

Dock of the Bay

On January 16, 1969, Soyuz 4 and Soyuz 5 docked in orbit. There was no pressurized tunnel connecting them. So Yevgeny Khrunov and Aleksei Yeliseyev put on spacesuits, climbed outside Soyuz 5, traveled across the docked spacecraft, and climbed into Soyuz 4. Two spacecraft had effectively become a tiny space station, but changing rooms required going outside.

Apollo 9 flew less than two months later and provides an interesting parallel. The command module and lunar module could dock, and crews could normally transfer internally. But what if the tunnel couldn’t be used? NASA planned to demonstrate a contingency EVA transfer from the lunar module to the command module.

Rusty Schweickart was supposed to perform the exercise, but space sickness caused NASA to shorten his EVA. He tested the lunar EVA suit and portable life-support backpack from the LM porch while Dave Scott partially exited the command module, but the complete external transfer was never performed.

Salyut and Almaz

On April 19, 1971, the Soviet Union launched Salyut 1, the first actual space station. The first crew failed to dock successfully. The second crew, Soyuz 11, spent more than three weeks aboard, but all three cosmonauts died during reentry when their Soyuz depressurized. There is some video from Salyut 1, but no audio.

The Salyut name also concealed a second program. Some of the stations were civilian Salyuts, while others were military Almaz reconnaissance stations similar in purpose to MOL. Salyut 2, 3, and 5 belonged to the Almaz line, although Salyut 2 failed before a crew could arrive.

Later Salyut stations gained a second docking port. That was a huge improvement because Progress cargo ships could bring supplies and fuel while a Soyuz remained attached as the crew’s ride home. Long-duration spaceflight was becoming practical rather than heroic improvisation. Of course, none of them rotated.

Skylab

The United States took a different route. Skylab was essentially an enormous converted Saturn V upper stage. Launched in 1973, it gave its crews something previous spacecraft had lacked: room.

Three crews occupied Skylab, staying as long as 84 days. They conducted solar astronomy, Earth observations, medical studies, and experiments designed to determine what happens when human beings spend months rather than days in weightlessness. After all, why build a giant rotating station if people could simply learn to live without gravity?

Then again, we learned that long-term microgravity isn’t free. Bones, muscles, cardiovascular systems, eyes, and assorted other bits of the human body complain when they don’t have proper gravity. Still, a nonrotating station was far easier to build, so rotating wheels stayed on the drawing board.

Freedom Isn’t Free

By the 1980s, NASA was ready to try again. In his 1984 State of the Union address, President Ronald Reagan directed NASA to build a permanently occupied space station within a decade. What eventually became known as Space Station Freedom was supposed to be a large modular facility assembled by the Space Shuttle.

It would support research, Earth observation, satellite servicing, and eventually serve as a staging point for missions beyond Earth orbit.

Freedom went through redesign after redesign as costs and requirements fought each other. It did not rotate. While NASA redesigned Freedom, the Soviets quietly launched something considerably more important.

Peace In Orbit

On February 20, 1986, the Soviet Union launched the core module of Mir.

The name means “peace,” although the Russian word can also mean “world.” Unlike the earlier Salyuts, Mir was designed from the beginning as a modular station. Additional laboratory and equipment modules arrived over the years and docked around its core.

It looked nothing like Noordung’s wheel. It looked more like somebody had been assembling an enormous machine in a garage and kept finding useful places to bolt things on.

Mir represented decades of incremental Soviet experience: Soyuz, docking, Salyut, Progress, long-duration crews, orbital repairs, and modular construction. It demonstrated that a space station could become not merely a spacecraft but a place — one that crews could maintain, modify, repair, and inhabit for months at a time.

Where’s My Wheel?

That may be the most surprising thing about the history of space stations. The rotating station wasn’t some goofy 1950s science-fiction invention. Serious engineers were proposing artificial gravity before anyone had launched anything into orbit. Oberth discussed rotating stations in 1923. Noordung drew a remarkably complete wheel station in 1929. Von Braun made the concept famous in the 1950s. NASA seriously studied rotating stations in the 1960s. The physics works.

We’ve simply never needed artificial gravity badly enough to pay the cost.
If you can tolerate microgravity, a station can be a collection of pressure vessels, trusses, solar arrays, and docking ports. If you insist on one g at a comfortable rotation rate, suddenly you are contemplating a structure hundreds or perhaps thousands of meters across.

Still, Edward Everett Hale put people aboard an artificial moon in 1869. Noordung put them aboard a rotating wheel in 1929. Kubrick had airline passengers walking around one in 1968. So after more than a century and a half of talking about space stations, I have only one question: When do I finally get my rotating space station?

[Makestreme] had always wanted to own a nice telescope, but found that budget would not stretch to anything above a cheap model with a limited 50 mm aperture. Wanting a better view of the heavens, the way forward was obvious—it was time to build a better telescope, instead!

The build is based around a 114 mm diameter mirror sourced from Amazon. It’s assembled inside a length of 5-inch PVC pipe of just under a meter to suit the 900 mm focal length of the concave reflector. 3D printed components are used to mount the mirror and control its position for proper focus and collimation. Traditionally, a reflector based telescope would use a mirror and eyepiece to provide a view to the user. However, [Makestreme] built this as a smart telescope, instead integrating a Raspberry Pi Camera Module 3 at the focal point. It’s connected to a Raspberry Pi Zero 2W, running off an 18650 lithium-ion cell and a 5 V boost module for portability. The Pi runs a Python script that hosts a small web server allowing access to the live camera feed along with controls for brightness, exposure, and gain. [Makestreme] then uses apps like SkyMap and SkEye to help aim the telescope at astronomical elements of interest.

If you’ve ever wanted to explore the heavens from down on Earth, building your own telescope is a great way to start. A camera-based build like this one can be a bit simpler than traditional builds, too, without the fuss of having to install an eyepiece.

People have lived in space stations for decades now, but something is wrong with them. Where are the big rotating wheels? You know the ones. They show up in old paintings of the future and, perhaps most memorably, in 2001: A Space Odyssey. Spin a great wheel in space, and people can stroll around inside with something that feels suspiciously like gravity. It seems like an obvious idea.

It is also an old idea. Much older than actual spaceflight, in fact. But to find the beginning of the space station, we have to go back to a time when powered aircraft were still several decades in the future.

A Moon Made of Bricks

In 1869, Edward Everett Hale published The Brick Moon in The Atlantic Monthly. The moon in question wasn’t natural. Hale imagined building a 200-foot-diameter sphere made from bricks and putting it into orbit as a navigation aid. Sailors could sight it and use its known orbit to determine their longitude. There was only one small problem: the thing was accidentally launched with people aboard.

That makes The Brick Moon generally regarded as not only the first fictional artificial satellite, but also the first fictional space station. Hale followed it in 1870 with Life on the Brick Moon, describing how the accidental colonists got along up there.

Hale didn’t have rockets. He proposed flinging the thing into the sky with giant flywheels, but, then again, it was 1869, so we’re inclined to cut him some slack. As the 19th century turned into the 20th, however, people started doing the math.

Konstantin Tsiolkovsky is best remembered for putting rocket flight on a sound theoretical footing. The Russian schoolteacher wrote extensively about orbital flight and space habitation, envisioning people living in orbit long before anyone had demonstrated that a liquid-fueled rocket actually worked. His ideas included rotating habitats to provide artificial gravity.

Hermann Oberth’s 1923 book Die Rakete zu den Planetenräumen — The Rocket into Planetary Space — Oberth went beyond fiction and seriously considered a permanently inhabited station. He envisioned it being periodically supplied by smaller rockets, serving as an observation and communications platform, and even acting as a jumping-off point for trips farther into space. He also suggested spinning the station to give the crew artificial gravity.

Enter The Wheel

But the space station that looks like the space station in your head probably comes from a different Hermann. Herman Potočnik was an Austro-Hungarian army officer and engineer who wrote under the name Hermann Noordung. In 1929, he published Das Problem der Befahrung des Weltraums, translated by NASA many years later as The Problem of Space Travel: The Rocket Motor.

Noordung didn’t merely say, “We should have a space station.” He drew one. His station consisted of several components, but the memorable one was the Wohnrad — literally the habitation wheel. Living quarters occupied a rotating ring connected to a central hub. Rotation provided artificial gravity, while other portions of the complex could remain weightless. He considered power, communications, observing Earth, astronomy, docking, and the practical business of living in orbit. NASA calls his work one of the first detailed technical designs for a space station.

If you have seen Wernher von Braun’s famous wheel station from the 1950s, you may notice something. Von Braun certainly knew Noordung’s work — he had cited it years earlier — and the family resemblance between Noordung’s 1929 Wohnrad and the wheel station that von Braun and Willy Ley presented to American readers in Collier’s in 1952 is hard to miss. The only place we have found the articles is the reprints in Horizons, by the AIAA (start with page 46).

Whatever the exact family tree, von Braun was the man who put the wheel-shaped station into American popular culture. In 1952 he described a 250-foot-class rotating station in Collier’s, accompanied by some gorgeous Chesley Bonestell artwork. A few years later he took the idea to television with Walt Disney.

If you’ve never seen these, they are worth your time. Disney’s 1955 Man in Space and Man and the Moon let von Braun explain a remarkably detailed vision of rockets, orbital stations, and trips to the Moon to a mass television audience. A generation of kids grew up expecting this stuff. What happened?

Gravity, More Or Less

The attraction of the wheel is simple. You can’t really make gravity, at least not without bringing along a planet-sized lump of mass, but acceleration will do nicely. Stand on the inside of a rotating ring, and the floor keeps accelerating you toward the axis. In your rotating frame, it feels as though something is pushing you outward against the floor.

The acceleration is a=ω²r where (r) is the radius and (ω) is the angular velocity. Sadly, the numbers explain part of the problem.

If you want one Earth gravity at the floor, you need to either spin fast or have a large ring. For example, at 1 RPM the ring has to be 1.79 km in diameter. Speed up to 2 RPM, and you can get away with 447 meters. At 4 RPM, you are down to 112 meters.

Seems like you could just keep going faster, but there’s a problem. Four RPM doesn’t sound very fast until you are inside the thing moving your head around.

Humans can adapt to rotation, but increasing the speed makes Coriolis effects increasingly noticeable. Move your head, climb a ladder toward the hub, throw something, or even walk spinward instead of anti-spinward, and the results aren’t quite what your inner ear expects. NASA artificial-gravity studies have often used approximately four RPM as an important practical region for human tolerance, although this isn’t a hard physical limit and training matters.

There’s also a gravity gradient. Your feet are farther from the axis than your head, so they weigh slightly more. Make the radius large enough, and you won’t notice. Make the station small enough, and things get strange quickly. So bigger is better except when it comes to cost, of course.

There is another oddity that movies sometimes get wrong. The outside circumference of the wheel is the floor. “Down” is away from the hub. Imagine a tire in space. You aren’t walking around on one of the flat sidewalls with the axle beside you. You are walking around the inside of the tread. So when a movie gives you a nice conventional room with a picture window on what looks like the outer wall, stop and think about where gravity ought to be pointing. Depending on the geometry, that window would probably be underfoot.

Stanley Kubrick got this wonderfully right in 2001: A Space Odyssey. Both Space Station V and the rotating centrifuge aboard Discovery make “down” follow the rotation. The famous jogging sequence works precisely because the circular wall of the set becomes the floor as the camera watches.

Next Time

Next time, I’ll look at early attempts to make a space station ranging from TASSEL, MTSS, and MARS to real Soviet and U.S. stations that had varying degrees of success. Spoiler alert: none of them are going to rotate for gravity.

Of course, people didn’t just imagine space stations. They also imagined moon bases, both fictional and actual.

While Hackaday’s bread and butter is, of course, hacks, we sometimes cover things that most of us are interested in that are probably out of reach for the typical hacker. Space, for example, is undeniably cool, even though your chances of putting yourself or even your own rover on the Moon aren’t very good at the moment (but, of course, give it time). If you are looking for something to put on your e-reader and you are also interested in space, save your money and get some downloadable books directly from NASA.

There’s something for everyone on the site. The site has four main categories: aeronautics, Hubble, science, and NASA history. Aeronautics has two volumes of “NASA’s Contributions to Aeronautics,” a book on the X-15, and a book about aviation pressure suits. Want to know more about the giant wind tunnel at Langley?

For the Hubble, you’ll find titles that have great images, of course, but also a book with an overview of the telescope or, if you prefer, about gravitational lensing.

The science titles go really deep with books on black holes, Landsat, the Cassini mission, and the Spitzer telescope. If you prefer history, there’s everything from a history of near-Earth object research to lessons from the Columbia tragedy for engineers, managers, and leaders. We were also interested in the book “Archaeology, Anthropology, and Interstellar Communication.”

The books are typically available in EPUB or PDF, and they are all free. Just what you need for your next plane trip or to round out your Calibre library.

We do love free books, we just can’t get enough.

After the little Mars helicopter Ingenuity blew everyone away with its performance, it was clear that a future Mars mission should involve more helicopters like it, with even more capabilities. The main proposal here is NASA’s SkyFall mission which would involve three autonomous helicopters, capable of searching for resources like water. To this end they would need a ground-penetrating radar system, with the antenna somehow folding away for landings, an idea that JPL is currently testing.

The SkyFall mission is currently penciled in to commence in 2028, following which it will be deployed from the Space Reactor-1 fission reactor-powered spacecraft based around elements of the now discarded Lunar Gateway space station. This obviously poses some uncertainties around when and if this mission will actually take place, but that doesn’t prevent JPL engineers from solving issues with these SkyFall helicopters.

As the antenna for the ground-penetrating radar extends beyond the landing legs, it was crucial that said antenna was flexible enough to simply fold in on itself like fabric. For this they used an existing flexible antenna design called Vivaldi, which was downscaled for the helicopters and subsequently tested to see how many simulated Mars landings it would be able to resist, as well as the effect of the cold nights and warm days.

We’re looking forward to seeing these SkyFall helicopters zip over the Martian surface. Maybe they can even swing by Ingenuity while they’re in the neighborhood.