satellite

174 Articles

Using An Old Satellite To See The Earth In A New Light

July 8, 2023 by 6 Comments

Snooping in on satellites is getting to be quite popular, enough so that the number of people advancing the state of the art — not to mention the wealth of satellites transmitting signals in the clear — has almost made the hobby too easy. An SDR, a homebrew antenna, and some off-the-shelf software, and you too can see weather satellite images on your screen in real time.

But where’s the challenge? That seems to be the question [dereksgc] asked and answered by tapping into S-band telemetry from an obsolete satellite. Most satellite hunters focus on downlinks in the L-band or even the VHF portion of the spectrum, which are within easy reach of most RTL-SDR dongles. However, the Coriolis satellite, which was launched in 2003, has a downlink firmly in the S-band, which at 2.2-GHz puts it just outside the high end of an RTL-SDR. To work around this, [dereksgc] bought a knock-off HackRF SDR and couple it with a wideband low-noise amplifier (LNA) of his own design. The dish antenna is also homebrewed from a used 1.8-m dish and a custom helical antenna for the right-hand circular polarized downlink signal.

As the video below shows, receiving downlink signals from Coriolis with the rig wasn’t all that difficult. Even with manually steering the dish, [dereksgc] was able to record a couple of decent passes with SDR#. Making sense of the data from WINDSAT, a passive microwave polarimetric radiometer that’s the main instrument that’s still working on the satellite, was another matter. Decoded with SatDump and massaged with Gimp, the microwave images of Europe are at least recognizable, mostly due to Italy’s distinctive shape.

Despite the distortion, seeing the planet’s surface via the microwaves emitted by water vapor is still pretty cool. If more traditional weather satellite images are what you’re looking for, those are pretty cool too.

Continue reading “Using An Old Satellite To See The Earth In A New Light” →

Miners Vs NASA: It’s A Nevada Showdown

July 6, 2023 by 74 Comments

Mining projects are approved or disapproved based on all kinds of reasons. There are economic concerns, logistical matters, and environmental considerations to be made. Mining operations can be highly polluting, or they can have outsized effects on a given area by sheer virtue of the material they remove or the byproducts they leave behind.

For a proposed lithium mining operation north of Las Vegas, though, an altogether stranger objection has arisen. NASA has been using the plot of land as a calibration tool, and it doesn’t want any upstart miners messing with its work. 

Continue reading “Miners Vs NASA: It’s A Nevada Showdown” →

Minimal Mods Make Commodity LNBs Work For QO-100 Reception

July 4, 2023 by 15 Comments

A word of advice: If you see an old direct satellite TV dish put out to the curb, grab it before the trash collector does. Like microwave ovens, satellite dishes are an e-waste wonderland, and just throwing them away before taking out the good stuff would be a shame. And with dishes, the good stuff basically amounts to the bit at the end of the arm that contains the feedhorn and low-noise block downconverter (LNB).

But what does one do with such a thing once it’s harvested? Lots of stuff, including modifying it for use with the QO-100 geosynchronous satellite (German link). That’s what [Sebastian Westerhold] and [Celin Matlinski] did with a commodity LNB, although it seems more like something scored on the cheap from one of the usual sources rather than picking through trash. Either way, these LNBs are highly integrated devices that at built specifically for satellite TV use, but with just a little persuasion can be nudged into the K-band to receive the downlink signals from hams using QO-100 as a repeater.

The mods are simple — snipping out the 25 MHz reference crystal on the LNB board and replacing it with a simple LC bandpass filter. This allows the local oscillator on the LNB to be referenced to an external signal generator; when fed with a 25.78 MHz signal, it’s enough to goose the LNB up to 10,490 MHz — right about the downlink frequency. [Sebastian] and [Celin] tested the mods and found that it was easily able to detect the third harmonics of a 3.5-ish GHz signal.

As for testing on actual downlink signals from the satellite, that’ll have to wait. For now, if you’re interested in satellite comms, and you live on the third of the planet covered by QO-100, keep an eye out for those e-waste LNBs and get to work.

A Quick And Easy Tape Measure Turnstile Antenna For MILSAT Snooping

June 30, 2023 by 16 Comments

The number of satellites whizzing by over our heads at any moment is staggering, and growing at a rapid rate as new constellations are launched. But sometimes it’s the old birds that are the most interesting, as is the case with some obsolete but still functional military communications satellites, which thanks to a lack of forethought are largely unsecured and easily exploitable. And all that’s needed to snoop in on them is a cheap ham radio and something like this simple and portable satcom antenna.

As proof of the global nature of the radio hobby, the design in the video below by Brit [Tech Minds] borrows heavily from previous work by Italian ham [Ivo Brugnera (I6IBE)], which itself was adapted to use 3D-printed parts in a German blog post a few years ago. The common thread is the use of tape measures for the elements of the aptly named turnstile antenna, a tried and true material for lightweight, foldable antennas that amateur radio enthusiasts have been using for years. The antenna is similar in design to the classic three-element Yagi-Uda, with a crossed pair of driven elements in the middle of a boom that also supports a reflector and a director. Strips of tape measure material are held to the 20-mm aluminum tubing boom with 3D-printed brackets. A phasing harness of precisely cut coax cable connects to the driven elements and runs down the boom; the quarter-wavelength loop serves to introduce the 90° phase shift needed for the circularly polarized signal from the satellites.

A quick scan with a vector antenna analyzer showed just how well this antenna performs on the 220-MHz band, and the antenna was easily able to pick up the Brazilian satellite pirate’s chatter. The tape measure elements make the antenna easy to handle and foldable, not to mention pretty cheap to build. And what’s not to love about that?

Continue reading “A Quick And Easy Tape Measure Turnstile Antenna For MILSAT Snooping” →

Methane-Tracking Satellites Hunt For Nasty Greenhouse Gas Emissions

May 30, 2023 by 41 Comments

Much of the reporting around climate change focuses on carbon dioxide. It’s public enemy number one when it comes to gases that warm the atmosphere, as a primary byproduct of fossil fuel combustion.

It’s not the only greenhouse gas out there, though. Methane itself is a particularly potent pollutant, and one that is being emitted in altogether excessive amounts. Satellites are now on the hunt for methane emissions in an attempt to save the world from this odorless, colorless gas.

Continue reading “Methane-Tracking Satellites Hunt For Nasty Greenhouse Gas Emissions” →

South Korea Successfully Sends Satellites To Orbit

May 30, 2023 by 8 Comments

South Korea’s KARI ( Korea Aerospace Research Institute ) successfully put a commercial satellite into orbit Thursday, achieving another milestone in their domestic space program. The Nuri rocket (aka KLSV-2) left the Naro Space Center launch pad on the southern coast of the peninsula at 18:24 KST, after a communications glitch in the pad’s helium tank facility caused a one-day slip. The primary payload was the 180 kg refrigerator-sized Earth observation satellite NEXTSat-2. It uses synthetic aperture radar (SAR) and also has instruments to observe neutrons in near-Earth orbit due to the impact of solar activity on cosmic radiation. In addition, seven CubeSats were successfully deployed:

  • Justek JLC-101-V1.2, to verify satellite orbital control system
  • Lumir, measuring cosmic radiation and testing rad-hardened microprocessor design
  • Cairo Space, weather observation and space debris technology demonstration
  • KASI-SAT (Korea Astronomy and Space Science Institute) SNIPE, actually four nano-sats which will achieve a 500 km – 600 km polar orbit and fly in formation to measure plasma variations.

It seems that SNIPE-C, Justek, and Lumir are having communication troubles and may be lost. Ground controllers are still searching. This launch comes almost one year after the previous launch of a dummy satellite in June, which we wrote about last year.

Continue reading “South Korea Successfully Sends Satellites To Orbit” →

ESA Juice’s RIME Antenna Breaks Free After Some Jiggling And Percussive Action

May 13, 2023 by 22 Comments

After ESA’s Jupiter-bound space probe Juice (Jupiter Icy Moons Explorer) launched on April 14th of this year, it initially looked as if it had squeezed out a refreshingly uneventful deployment, until it attempted to unfurl its solar panels and antennae. One of these antennae, for the RIME (Radar for Icy Moons Exploration) instrument that uses ice-penetrating radar to get a subsurface look at Jupiter’s moons, ended up being rather stuck. Fortunately, on May 12th it was reported that ESA engineers managed to shock the sticky pin loose.

Release of the jammed antenna coinciding with the actuation of the NEA ('NEA 6 Release'). The antenna wobbles about before settling in a locked position. (Credit: ESA)
Release of the jammed antenna coinciding with the actuation of the NEA (‘NEA 6 Release’). The antenna wobbles about before settling in a locked position. (Credit: ESA)

We previously covered the discovery of Juice’s  RIME antenna troubles, with one of the retaining pins that hold the antenna in place in its furled position stubbornly refusing to shift the few millimeters that would have allowed for full deployment. Despite the high-tech nature of the Juice spacecraft, the optimal solution to make the pin move was simply to try and shake it loose.

Attempts were initially made using the spacecraft’s thrusters to shake the whole vehicle, as well as by warming it in sunlight. Each of these actions seemed to help a little bit, but the breakthrough came when a non-explosive actuator (NEA) was actuated in the jammed bracket. This almost fully fixed the problem, leading the team in charge to decide to fire another NEA, which finally allowed the pin to fully shift and the antenna to fully deploy and lock into place.

Assuming no further issues occur during Juice’s long trip through the Solar System, Juice is expected to arrive at Jupiter after four gravity assists in July of 2031. There it will perform multiple science missions until a planned deorbit on Ganymede by late 2035.