satellite

166 Articles

One Method For Removing Future Space Junk

March 22, 2023 by 18 Comments

When sending satellites into space, the idea is to place them into as stable an orbit as possible in order to maximize both the time the satellite is useful and the economics of sending it there in the first place. This tends to become rather untenable as the amount of space junk continues to pile up for all but the lowest of orbits, but a team at Brown University recently tested a satellite that might help solve this problem, at least for future satellite deployments.

The main test of this satellite was its drag sail, which increases its atmospheric drag significantly and reduces its spaceflight time to around five years. This might make it seem like a problem from an economics standpoint, as it’s quite expensive to build satellites and launch them into space, but this satellite solves these problems by being both extremely small to minimize launch costs, and also by being built out of off-the-shelf components not typically rated for spaceflight. For example, it gets its power solely from AA batteries and uses an Arduino for its operation and other research.

The satellite is currently in orbit, and has already descended from an altitude of 520 km to 470 km. While it won’t help reduce the existing amount of debris in orbit, the research team hopes to demonstrate that small satellites can be affordable and economically feasible without further contributing to the growing problem of space junk. If you’re looking to launch your own CubeSat one day, take a look at this primer which goes over most of the basics.

Hunting For Space Pirates

February 24, 2023 by 14 Comments

Ever since the first artificial satellite was launched into orbit, radio operators around the world have been tuning in to their space-based transmissions. Sputnik 1 only sent back pulses of radio waves, but in the decades to follow ever more advanced radio satellites were put into service that could support two-way communications from Earth to space and back again.

Some of these early satellites were somewhat lacking in security, though, and have been re-purposed by various pirates around the world for their own ends. [Gabe] aka [saveitforparts] is here to show us how to hunt for those pirates and listen in on their radio traffic.

Pirates on these satellites have typically used them for illicit activities, and it is still illegal to use them for non-governmental or non-military purposes, so [Gabe] notes that he will only be receiving, not transmitting. The signals he is tuning in to are VHF transmissions, specifically around 220 MHz. That puts them easily within the reach of the RTL-SDR and common ham radio equipment, but since they are coming from space a more directional antenna is needed. [Gabe] quickly builds a Yagi antenna from scrap, tuned specifically to 255 MHz, and mounts it to an old remote-controlled security camera mount which allows him to point it exactly at the satellite and monitor transmissions.

From there he is able to pick up what looks like a few encrypted and/or digital transmissions, plus analog transmissions of likely pirates speaking a language he guesses to be Portuguese. He also hears what he thinks is a foreign TV broadcast, but oddly enough turns out to be NPR. These aren’t the only signals in space to tune to, either. There are plenty of purpose-built ham radio satellites available for any licensed person to use, and we’ve also seen this other RTL-SDR configured to snoop on Starlink signals.

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Hackaday Links: January 8, 2023

January 8, 2023 by 12 Comments

Something odd is afoot in the mountains around Salt Lake City, Utah, at least according to local media reports of remote radio installations that have been popping up for at least the past year. The installations consist of a large-ish solar panel, a weatherproof box full of batteries — and presumably other electronics, including radios — and a mast bearing at least one antenna. Local officials aren’t quite sure who these remote setups belong to or what they’re intended to do, but the installations obviously represent a huge investment in resources.

The one featured in the story was located near the summit of Twin Peaks, which is about 11,000 feet (3,300 meters) in elevation, which with that much gear was probably a hell of a hike. Plus, the owner took great pains to make sure the site would withstand the weather, with antenna mast guy wires that must have required lugging a pretty big drill up with them. There aren’t any photos of the radios in the enclosure, but one photo shows a 900-MHz LORA antenna, while another shows what appears to be a panel antenna, perhaps pointing toward another site. So maybe a LORA mesh network? Some comments in the Twitter thread show most people are convinced this is a Helium crypto mining rig, but the Helium Explorer doesn’t show any hotspots listed in that area. Either way, the owners are out of luck, since their gear is being removed if it’s on public land.

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Snooping On Starlink With An RTL-SDR

September 23, 2022 by 21 Comments

With an ever-growing constellation of Starlink satellites whizzing around over our heads, you might be getting the urge to start experimenting with the high-speed internet service. But at $100 or more a month plus hardware, the barrier to entry is just a little daunting for a lot of us. No worries, though — if all you’re interested in is tracking [Elon]’s birds, it’s actually a pretty simple job.

Now, we’re not claiming that you’ll be able to connect to Starlink and get internet service with this setup, of course, and neither is the delightfully named [saveitforparts]. Instead, his setup just receives the beacon signals from Starlink satellites, which is pretty interesting all by itself. The hardware consists of his “Picorder” mobile device, which sports a Raspberry Pi, a small LCD screen, and a host of sensors, including an RTL-SDR dongle. To pick up the satellite beacons, he used a dirt-cheap universal Ku-band LNB, or low-noise block downconverter. They’re normally found at the focal point of a satellite TV dish, but in this case no dish is needed — just power it up with a power injector and point it to the sky. The signals show up on the Picorder’s display in waterfall mode; curiously, the waterfall traces look quite similar to the patterns the satellites make in the night sky, much to the consternation of astronomers.

Of course, you don’t have to have a Picorder to snoop in on Starlink — any laptop and SDR should work, despite [saveitforparts]’ trouble in doing so. You shouldn’t have much trouble replicating the results by following the video below, which also has a few tips on powering an LNB for portable operations.

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IGY: The Year We All Got Along

September 20, 2022 by 24 Comments

If you are a Steely Dan fan, you might know the Donald Fagen song, “IGY.” In it, Fagen sings about a rosy future with high-speed undersea rail, solar power, giant computers making life better, and spandex jackets. Since that song was on the 1982 album Nightfly, it is already too old for some people to remember, but the title goes back even further: the International Geophysical Year which was actually a little longer than a year in 1957 and 1958. The year was a concerted effort by 67 countries to further mankind’s knowledge of the Earth. It was successful,  and was big news in its day, although not much remembered now.

The real origin dates back to even earlier. In 1882 and 1932 there were International Polar Years dedicated to researching the polar regions of the Earth. In a way, it makes sense to do this. Why should 60 or more countries each mount difficult, dangerous, and expensive expeditions to such a hostile environment? However, instead of a third polar year, James Van Allen (who has a famous belt) and some other scientists felt that advances in many fields made it the right time to study geophysics. From the scientific point of view, the IGY coincided with the solar activity cycle maximum. But there were other forces at play, too.

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AntRunner Is The Satellite Antenna Mount You Need To Take With You

September 17, 2022 by 13 Comments

It stands to reason, that should you wish to communicate with a satellite, whatever antenna you use should point at that satellite. Some of us have done this by hand, following the bright dot of the space station in the night sky. Still, for anything more serious than trying to catch a fleeting SSTV image, a more robust solution is called for. In other words, a motorized antenna rotator, and AntRunner from [Wuxx] is just the ticket. Better still, it’s portable for those /p operating sessions off the beaten track.

The rotator itself is an az-el design with a couple of geared stepper motors. The full mechanism design has been published, but it shouldn’t be too difficult to copy. The interesting part is the controller and software, which can work with Gpredict, Hamlib, and SDR for automated satellite tracking. The controller is as straightforward as an ESP32 running the ESP port of GRBL.

So here’s a portable antenna rotator that’s accessible and widely supported, what’s not to like? As you might expect though, it’s not the first we’ve seen. In fact, the 2014 Hackaday Prize was won by SatNOGs, which includes a 3D printed antenna positioner.

Thanks [Abe Tusk] for the tip!

Swarm Vs. Iridium: Which Satellite IoT Service Is Right For You?

August 12, 2022 by 15 Comments

In a world where it seems like everyone’s face is glued to a device screen, the idea that wireless service might be anything other than universal seems just plain silly. But it’s not, as witnessed by vast gaps in cell carrier coverage maps, not to mention the 70% of the planet covered by oceans. The lack of universal coverage can be a real pain for IoT applications, which is a gap that satellite-based IoT services aim to fill.

But which service is right for your application? To help answer that question, [Mike Krumpus] has performed the valuable work of comparing the services offered by Swarm and Iridium in a real-world IoT shootout. On the face of it, the match-up seems a little lopsided — Iridium has been around forever and has a constellation of big satellites and an extensive ground-based infrastructure. But as our own [Al Williams] discovered when he tested out Swarm, there’s something to be said for having a lot of 1/4U Cubesats up there.

[Mike] picked up the gauntlet and did head-to-head tests of the two services under real-world conditions. Using the same Swarm development kit that [Al] used for his test, alongside an Iridium dev board of his own design, [Mike] did basic tests on uplink and downlink times for a short message on each service. We couldn’t find specs on the test message length, but Swarm’s FAQ indicates that packets are limited to 192 bytes, so we assume they’re both in that ballpark. Iridium was the clear winner on uplink and downlink times, which makes sense because Swarm’s constellation is much smaller at this point and leaves large gaps in coverage. But when you consider costs, Swarm wins the day; what would cost over $1,500 with Iridium would set you back a mere $60 with Swarm.

The bottom line, as always, depends on your application and budget, but [Mike]’s work makes it easier to do that analysis.