Voyager Command Glitch Causes Unplanned Pause In Communications

July 29, 2023 by Dan Maloney 31 Comments

Important safety tip: When you’re sending commands to the second-most-distant space probe ever launched, make really, really sure that what you send isn’t going to cause any problems.

According to NASA, that’s just what happened to Voyager 2 last week, when uplinked commands unexpectedly shifted the 46-year-old spacecraft’s orientation by just a couple of degrees. Of course, at a distance of nearly 20 billion kilometers, even fractions of a degree can make a huge difference, especially since the spacecraft’s high-gain antenna (HGA) is set up for very narrow beamwidths; 2.3° on the S-band channel, and a razor-thin 0.5° on the X-band side. That means that communications between the spacecraft and the Canberra Deep Space Communication Complex — the only station capable of talking to Voyager 2 now that it has dipped so far below the plane of the ecliptic — are on pause until the spacecraft is reoriented.

Luckily, NASA considered this as a possibility and built safety routines into Voyager‘s program that will hopefully get it back on track. The program uses the onboard star tracker to get a fix on the bright star Canopus, and from there figures out which way the spacecraft needs to move to get pointed back at Earth. The contingency program runs automatically several times a year, just in case something like this happens.

That’s the good news; the bad news is that the program won’t run again until October 15. While that’s really not that far away, mission controllers will no doubt find it an agonizingly long time to be incommunicado. And while NASA is outwardly confident that communications will be restored, there’s no way to be sure until we actually get to October and see what happens. Fingers crossed.

Would We Recognize Extraterrestrial Technology If We Saw It?

July 28, 2023 by Maya Posch 92 Comments

There’s a common critique in science fiction series like Star Trek about the extraterrestrial species not looking ‘alien’ enough, as well as about their technology being strangely similar to our own, not to mention compatible to the point where their widgets can be integrated into terrestrial systems by any plucky engineer. Is this critique justified, or perhaps more succinctly put: if we came across real extraterrestrial life with real extraterrestrial technology, would we even notice? Would an alien widget borrowed of an alien spacecraft even work with our own terrestrial spacecraft’s system?

Within the domain of exobiology there are still plenty of discussions on the possible formation and evolutionary paths conceivable within the Universe, but the overarching consensus seems to be that it’s hard to escape the herding effect of fundamental physics. For lifeforms, carbon-based chemistry is the only reasonable option, and when it comes to technology, it’s hard to not end up at technology using the same physical principles which we presume to exist across the Universe, which would practically guarantee some level of interoperability.

What’s notable here is that over the past years, a number of people have claimed to have observed potential alien technology in our Solar System, in particular the ʻOumuamua asteroid in 2017 and a more recent claim by astrophysicist Abraham Loeb regarding an interstellar meteor that impacted Earth in 2019, which he says could be proof of ‘alien technology’. This raises the question of whether we are literally being pummeled by extraterrestrial spacecraft these days.

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Discussing The Finer Points Of Space-Worthy Software

July 17, 2023 by Tom Nardi 28 Comments

At the dawn of the Space Race, when computers were something that took up whole rooms, satellites and probes had to rely on analog electronics to read from their various sensors and transmit the resulting data to the ground. But it wasn’t long before humanity’s space ambitions outgrew these early systems, which lead to vast advancements in space-bound digital computers in support of NASA’s Gemini and Apollo programs. Today, building a spacecraft without an onboard computer (or even multiple redundant computers) is unheard of. Even the smallest of CubeSats is likely running Linux on a multi-core system.

As such, software development has now become part an integral part of spacecraft design — from low-level code that’s responsible for firing off emergency systems to the 3D graphical touchscreen interfaces used by the crew to navigate the craft. But as you might expect, the stakes here are higher than any normal programming assignment. If your code locks up here on Earth, it’s an annoyance. If it locks up on a lunar lander seconds before it touches down on the surface, it could be the end of the mission.

To get a bit more insight into this fascinating corner of software development, we invited Jacob Killelea to host last week’s
Software for Satellites Hack Chat. Jacob is an engineer with a background in both aero and thermodynamics, control systems, and life support. He’s written code for spacecraft destined for the Moon, and perhaps most importantly, is an avid reader of Hackaday.

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Gravity Wave Detector Is Galactic Sized

July 15, 2023 by Al Williams 13 Comments

Detecting gravity waves isn’t easy. But what if you had a really big detector for a long time? That’s what researchers did when they crunched 15 years’ worth of data from the NANOGrav data set. The data was collected from over 170 radio astronomers measuring millisecond pulsars as a way to potentially detect low-frequency gravity waves.

Millisecond pulsars spin fast and make them ideal for the detection of low-frequency gravity waves, which are difficult to detect. The bulk of the paper is about the high-powered data analysis for a very large data set.

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Listening In On A Deep-Space Satellite As It Returns Home

July 13, 2023 by Dan Maloney 1 Comment

We’ve covered dozens of projects about getting images of Earth’s weather straight from the source. It’s not too much of a trick to download images straight from our constellation of weather satellites, but what about space weather? We’ve got satellites for that too, of course, but to get a good look at the Sun, they’re out of reach of most homebrew ground stations.

That’s about to change, though, as STEREO-A returns to our neighborhood after a 17-year absence, making citizen science a reasonable proposition. The STEREO mission — Solar Terrestrial Relations Observatory — was launched in 2006 with a pair of satellites in heliocentric orbits. STEREO-B was lost in 2014 due to a navigational glitch, but STEREO-A has spent a lot of the intervening years watching the backside of the Sun relative to the Earth. As [Scott Tilley] explains, the satellite is now approaching inferior conjunction, where it will pass between the Earth and the Sun.

This close pass makes STEREO-A’s X-band deep-space beacon readily available to hobbyist-scale equipment, like [Scott]’s 66-cm dish antenna. The dish is mounted on an alt-az telescope mount for tracking, and sports a host of gear at the focus, like LNAs, filters, mixers, and an Ettus B200 SDR. It’s not a cheap setup, but compared to what’s usually needed to listen to STEREO-A, it’s a bargain. The process of demodulating and decoding the signals was a bit more involved, though, requiring not only SatDump and some custom code but also a lot of patience. The images are worth the wait, though; [Scott] shares some amazing shots of our increasingly active Sun as well as animations of recent sunspot activity.

If you’re interested in getting in on the STEREO-A action, you’d better get hopping — the satellite will only be in the neighborhood for a few more months before heading off for another pass around the back of the Sun.

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

July 8, 2023 by Dan Maloney 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.

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Russian Weather Satellite Reuses Name, Yields Images

July 7, 2023 by Al Williams 13 Comments

Which Russian weather satellite has the name Meteor 2? According to [saveitforparts], pretty much all of them. He showed how to grab images from an earlier satellite with the same name a while back. That satellite, though, met with some kind of disaster, so he’s posted a new video about reading data from the new Meteor 2 and you can watch it below.

The interesting part, we thought, was that the software he’s using, Raspberry-NOAA v2, doesn’t know about this incarnation of the bird which has only been up for a few weeks. That means he had to find a satellite with similar orbital parameters. Eventually, the program will have the setup for this satellite.

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