It’s A Bird! It’s A Plane! It’s… An Air Breathing Satellite?!

September 24, 2025 by Tyler August 18 Comments

The big problem with Low Earth Orbit is, oddly enough, air resistance. Sure, there’s not enough air to breathe in space, but there is enough to create drag when you’re whipping around the planet at 28,000 km/h (17,000 mph) or more. Over time, that adds up to a decaying orbit. [Eager Space] recently did a video summarizing a paradoxical solution: go even lower, and let the air work for you.

So called air-breathing satellites would hang out in very low earth orbit– still well above the Karman line, but below 300 km (186 miles)– where atmospheric drag is too dominant for the current “coast on momentum” satellite paradigm to work. There are advantages to going so low, chiefly for communications (less latency) and earth observation (higher resolutions). You just need to find a way to fight that drag and not crash within a couple of orbits.

It turns out this space isn’t totally empty (aside from the monoatomic oxygen) as missions have been at very low orbits using conventional, Xenon-fueled ion engines to counter drag. The xenon runs out pretty quick in this application, though, and those satellites all had fairly short lifetimes.

That’s where the air-breathing satellites come in. You don’t need a lot of thrust to stabilize against drag, after all, and the thin whisps of air at 200 km or 300 km above ground level should provide ample reaction mass for some kind of solar-electric ion engine. The devil is in the details, of course, and [Eager Space] spends 13 minutes discussing challenges (like corrosive monoatomic oxygen) and various proposals.

Whoever is developing these satellites, they could do worse than talk to [Jay Bowles], whose air-breathing ion thrusters have been featured here several times over the years.

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Receiving Radio Signals From Space Like It’s 1994

August 28, 2025 by Bryan Cockfield 19 Comments

For certain situations, older hardware is preferred or even needed to accomplish a task. This is common in industrial applications where old machinery might not be supported by modern hardware or software. Even in these situations though, we have the benefit of modern technology and the Internet to get these systems up and running again. [Old Computers Sucked] is not only building a mid-90s system to receive NOAA satellite imagery, he’s doing it only with tools and equipment available to someone from this era.

Of course the first step here is to set up a computer and the relevant software that an amateur radio operator would have had access to in 1994. [Old Computers Sucked] already had the computer, so he turned to JV-FAX for software. This tool can decode the APT encoding used by some NOAA satellites without immediately filling his 2 MB hard drive, so with that out of the way he starts on building the radio.

In the 90s, wire wrapping was common for prototyping so he builds a hardware digitizer interface using this method, which will be used to help the computer interface with the radio. [Old Computers Sucked] is rolling his own hardware here as well, based on a Motorola MC3362 VHF FM chip and a phase-locked loop (PLL), although this time on a PCB since RF doesn’t behave nicely with wire wrap. The PCB design is also done with software from the 90s, in this case Protel which is known today as Altium Designer.

In the end, [Old Computers Sucked] was able to receive portions of imagery from weather satellites still using the analog FM signals from days of yore, but there are a few problems with his build that are keeping him from seeing perfectly clear imagery. He’s not exactly sure what’s wrong but he suspects its with the hardware digitizer as it was behaving erratically earlier in the build. We admire his dedication to the time period, though, down to almost every detail of the build. It reminds us of [saveitforparts]’s effort to get an 80s satellite internet experience a little while back.

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SkyRoof, A New Satellite Tracker For Hams

June 10, 2025 by Bryan Cockfield 13 Comments

Communicating with space-based ham radio satellites might sound like it’s something that takes a lot of money, but in reality it’s one of the more accessible aspects of the hobby. Generally all that’s needed is a five-watt handheld transceiver and a directional antenna. Like most things in the ham radio world, though, it takes a certain amount of skill which can’t be easily purchased. Most hams using satellites like these will rely on some software to help track them, which is where this new program from [Alex Shovkoplyas] comes in.

The open source application is called SkyRoof and provides a number of layers of information about satellites aggregated into a single information feed. A waterfall diagram is central to the display, with not only the satellite communications shown on the plot but information about the satellites themselves. From there the user can choose between a number of other layers of information about the satellites including their current paths, future path prediction, and a few different ways of displaying all of this information. The software also interfaces with radios via CAT control, and can even automatically correct for the Doppler shift that is so often found in satellite radio communications.

For any ham actively engaged in satellite tracking or space-based repeater communications, this tool is certainly worth trying out. Unfortunately, it’s only available for Windows currently. For those not looking to operate under Microsoft’s thumb, projects such as DragonOS do a good job of collecting up the must-have Linux programs for hams and other radio enthusiasts.

Inside Starlink’s User Terminal

May 14, 2025 by Al Williams 34 Comments

If you talk about Starlink, you are usually talking about the satellites that orbit the Earth carrying data to and from ground stations. Why not? Space is cool. But there’s another important part of the system: the terminals themselves. Thanks to [DarkNavy], you don’t have to tear one open yourself to see what’s inside.

The terminal consists of two parts: the router and the antenna. In this context, antenna is somewhat of a misnomer, since it is really the RF transceiver and antenna all together. The post looks only at the “antenna” part of the terminal.

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Satellite Internet On 80s Hardware

February 14, 2025 by Bryan Cockfield 3 Comments

Portability has been a goal of a sizable section of the computing world for many decades now. While the obvious products of this are laptops, there are a number of “luggable” PCs that pack more power while ostensibly maintaining their portability. Going back in time past things like the LAN party era of the 90s and 00s takes us to the early era of luggables, with the Commodore SX-64 being one such machine of this era. Its portability is on display in this video where [saveitforparts] is using it to access the Internet over satellite.

The project uses a Glocom Inmarsat modem and antenna to access the internet through a geostationary satellite, but since this computer is about four decades old now this takes a little bit more effort than a modern computer. A Teensy microcontroller is used to emulate a modem so that the Ethernet connection from the satellite modem can be understood by the Commodore. There was a significant amount of setup and troubleshooting required as well, especially regarding IP addresses and networking but eventually [saveitforparts] got the system up and running well enough to chat on a BBS and browse Wikipedia.

One thing he found that might make a system like this relevant for a modern user is that the text-only mode of the Commodore significantly limited data use. For a normal Internet connection this might be a problem, but on a geostationary satellite network where the data is orders of magnitude more expensive, this can be surprisingly helpful. We might not recommend an SX-64 system specifically, but one inspired by similar computers like this text-only cyberdeck might do the trick with the right networking connections.

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Communicating With Satellites Like It’s 1957

February 3, 2025 by Bryan Cockfield 14 Comments

When the first artificial satellite, Sputnik, was put into orbit around Earth, anyone in the path of the satellite could receive the beeps transmitted by the satellite provided they had some simple radio equipment. Of course, there was no two-way communication with this satellite, and it only lasted a few weeks before its batteries died. Here in the future, though, there are many more satellites in orbit and a few are specifically meant for ham radio operators. And, like the ’50s, it doesn’t take too much specialized equipment to communicate with them, although now that communication can be two-way.

The first step in this guide by [W2PAK] is to know where these satellites are in the sky. The simplest way to do that is to use a smartphone app called GoSatWatch and, when configured for a specific location, shows the satellites currently overhead. After that it’s time to break out the radio gear, which can be surprisingly inexpensive. A dual-band handheld is required since satellite uplink and downlink can be on different bands, and the antenna can be made from simple parts as well as [W2PAK] demonstrates in a separate video. Combined, this can easily be done for less than $100. [W2PAK] also goes over the proper format and etiquette for a satellite contact as well, so a new operator can pick it up quickly.

Using satellites as repeaters opens up a lot of capabilities when compared to terrestrial communications. Especially for operators with entry-level licenses who are restricted to mostly VHF and UHF, it adds a challenge as well as significantly increased range compared to ground-based repeaters and line-of-sight communications. There are plenty of activities around satellites that don’t require a license at all, too, like this project which downloads weather imagery from weather satellites.

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Making The Longest-Distance Radio Contact Possible

January 25, 2025 by Bryan Cockfield 29 Comments

One of the more popular activities in the ham radio world is DXing, which is attempting to communicate with radio stations as far away as possible. There are some feats that will earn some major credibility in this arena, like two-way communication with Antarctica with only a few watts of power, long-path communication around the globe, or even bouncing a signal off the moon and back to a faraway point on Earth. But these modes all have one thing in common: they’re communicating with someone who’s also presumably on the same planet. Barring extraterrestrial contact, if you want to step up your DX game you’ll want to try to contact some of our deep-space probes (PDF).

[David Prutchi] aka [N2QG] has been doing this for a number of years now and has a wealth of knowledge and experience to share. He’s using both a 3.2 meter dish and a 1.2 meter dish for probing deep space, as well as some custom feed horns and other antennas to mount to them. Generally these signals are incredibly small since they travel a long way through deep space, so some amplification of the received signals is also needed. Not only that, but since planets and satellites are all moving with respect to each other, some sort of tracking system is needed to actively point the dish in the correct direction.

With all of that taken care of, it’s time to see what sort of signals are coming in. Compared to NASA’s 70-meter antennas used to communicate with deep space, some signals received on smaller dishes like these will only see the carrier wave. This was the case when an amateur radio group used an old radio telescope to detect one of the Voyager signals recently. But there are a few cases where [David] was able to actually receive data and demodulate it, so it’s not always carrier-only. If you’re sitting on an old satellite TV dish like these, we’d certainly recommend pointing it to the sky to see what’s out there. If not, you can always 3D print one.