from the you're-throwing-a-kink-in-my-telemetry dept.
The engineering team with NASA's Voyager 1 spacecraft is trying to solve a mystery: The interstellar explorer is operating normally, receiving and executing commands from Earth, along with gathering and returning science data. But readouts from the probe's attitude articulation and control system (AACS) don't reflect what's actually happening onboard.
The AACS controls the 45-year-old spacecraft's orientation. Among other tasks, it keeps Voyager 1's high-gain antenna pointed precisely at Earth, enabling it to send data home. All signs suggest the AACS is still working, but the telemetry data it's returning is invalid. For instance, the data may appear to be randomly generated, or does not reflect any possible state the AACS could be in.
[...] It's possible the team may not find the source of the anomaly and will instead adapt to it, Dodd said. If they do find the source, they may be able to solve the issue through software changes or potentially by using one of the spacecraft's redundant hardware systems.
At only 160 baud, I bet it takes quite a while to update the onboard software on NASA Patch Tuesdays.
Related Stories
NASA fixed the glitch that caused Voyager 1 to send back jumbled data:
Back in May, NASA reported that the Voyager 1 space probe was sending back jumbled or inaccurate telemetry data. The probe itself seemed to be in good shape, with a signal that's still strong enough to beam back information, and nothing was triggering its fault protection systems that would put it in "safe mode." According to NASA, the Voyager team has not only figured the problem out since then — it has also solved the issue.
Turns out we're getting jumbled data here on Earth, because the probe's attitude articulation and control system (AACS) has been sending back information through an onboard computer that had stopped working years ago. The computer was corrupting the data before it even went out. Voyager project manager Suzanne Dodd said that when her team suspected that this was the issue, they implemented a low-risk fix: They commanded the AACS to send its data through the probe's working computer again.
Previously:
Engineers Investigating NASA's Voyager 1 Telemetry Data
Voyager 1 is still alive out there, barreling into the cosmos more than 15 billion miles away. However, a computer problem has kept the mission's loyal support team in Southern California from knowing much more about the status of one of NASA's longest-lived spacecraft.
The computer glitch cropped up on November 14, and it affected Voyager 1's ability to send back telemetry data, such as measurements from the spacecraft's science instruments or basic engineering information about how the probe was doing. [...] "It would be the biggest miracle if we get it back. We certainly haven't given up," said Suzanne Dodd, Voyager project manager at NASA's Jet Propulsion Laboratory, in an interview with Ars. "There are other things we can try. But this is, by far, the most serious since I've been project manager."
Dodd became the project manager for NASA's Voyager mission in 2010, overseeing a small cadre of engineers responsible for humanity's exploration into interstellar space. Voyager 1 is the most distant spacecraft ever, speeding away from the Sun at 38,000 mph (17 kilometers per second). [...] The latest problem with Voyager 1 lies in the probe's Flight Data Subsystem (FDS), one of three computers on the spacecraft working alongside a command-and-control central computer and another device overseeing attitude control and pointing. [...] In November, the data packages transmitted by Voyager 1 manifested a repeating pattern of ones and zeros as if it were stuck, according to NASA. Dodd said engineers at JPL have spent the better part of three months trying to diagnose the cause of the problem. She said the engineering team is "99.9 percent sure" the problem originated in the FDS, which appears to be having trouble "frame syncing" data. [...] "It's likely somewhere in the FDS memory," Dodd said. "A bit got flipped or corrupted. But without the telemetry, we can't see where that FDS memory corruption is."
[...] "We have sheets and sheets of schematics that are paper, that are all yellowed on the corners, and all signed in 1974," Dodd said. "They're pinned up on the walls and people are looking at them. That's a whole story in itself, just how to get to the information you need to be able to talk about the commanding decisions or what the problem might be." [...] "It is difficult to command Voyager," Dodd said. "We don't have any type of simulator for this. We don't have any hardware simulator. We don't have any software simulator... There's no simulator with the FDS, no hardware where we can try it on the ground first before we send it. So that makes people more cautious, and it's a balance between getting commanding right and taking risks."
[...] The spacecraft's vast distance and position in the southern sky require NASA to use the largest 230-foot (70-meter) antenna at a Deep Space Network tracking site in Australia, one of the network's most in-demand antennas.
"The data rates are very low, and this anomaly causes us not to have any telemetry," Dodd said. "We're kind of shooting in the blind a little bit because we don't know what the status of the spacecraft is completely."
Previously on SoylentNews:
Engineers Work to Fix Voyager 1 Computer - 20231215
(Score: 1, Funny) by Anonymous Coward on Monday May 23 2022, @05:58PM
Soon it will come home! Please tell me Shatner isn't dead yet.
(Score: 4, Interesting) by maxwell demon on Monday May 23 2022, @06:22PM (10 children)
With 69.63 kilobytes of total memory you need about 7.5 minutes at 160 bits per second (according to your link, the actual baud rate is 320; however the net bit rate is the relevant quantity for this calculation, and that one indeed is 160 pbs). [nasa.gov]
The Tao of math: The numbers you can count are not the real numbers.
(Score: 0) by Anonymous Coward on Monday May 23 2022, @06:28PM (6 children)
I wonder what the current latency is, I assume they use a protocol that doesn't suffer from it but still. Takes a long time to know if your patch worked.
(Score: 3, Informative) by Anonymous Coward on Monday May 23 2022, @06:53PM (5 children)
Voyager is nearly 156.47 AU from the Sun, so 2d12h41.3m ±8.3 minutes depending on time of year.
(Score: 1, Informative) by Anonymous Coward on Monday May 23 2022, @07:00PM (4 children)
Edit:That's each way, so a round trip is just over five days.
(Score: 2, Informative) by Anonymous Coward on Monday May 23 2022, @07:37PM (3 children)
14.5 billion miles / 186,000 miles per second = ~78,000 seconds one way, which is a little less than a day (one way). At first I thought you just doubled your number for round trip twice by accident, but it's still off by many hours.
Either way, with this kind of ping time I'm afraid I will have a hard time making sick headshots in Counterstrike.
(Score: 0, Redundant) by Anonymous Coward on Monday May 23 2022, @07:51PM
Don't forget to calculate in all the added advertising they have to send too. Every device in the universe MUST be overflowing and dripping with Brawndo-e advertising goodness. When V'ger returns to earth it will be selling blue LED cockrings to all the whales.
(Score: 4, Insightful) by JoeMerchant on Monday May 23 2022, @09:06PM
Every successful exchange of messages between Earth and Voyager is sicker than the sickest headshot ever taken in Counterstrike, by many orders of magnitude.
🌻🌻 [google.com]
(Score: 0) by Anonymous Coward on Tuesday May 24 2022, @12:35AM
I must have fat-fingered my calculator something fierce. Retrying I get 1301 minutes, or 21.68h each way. Thanks for the correction.
(Score: 3, Disagree) by Immerman on Tuesday May 24 2022, @12:48AM (2 children)
This is your friendly reminder that baud is a very different thing than bit rate. They can have the same numerical value in the simplest case, but in general the bit rate is substantially higher than the baud rate.
Bit rate is exactly what it says on the tin - how many bits can be transmitted per second.
Baud rate though is how many times the signal changes per second.
In the simplest case of a pure digital signal you might have 0V=0 and 3V=1, so each change of signal transmits 1 bit of information, and then the baud rate would match the bit rate.
In a slightly more complex system you might involve several different voltages - e.g. 0V=0, 1V=1, 2V=2, 3V=3 - so that each signal change transmits 2 bits of information, and thus the bit rate is 2x the baud rate.
Later phone modems used phase modulation of an analog sinusoidal signal rather than discrete voltages, but the principle was the same. If I recall correctly 8 states (3 bits) per signal change was pretty common as modem speeds started to plateau. And of course there's no inherent need to stick to powers of 2: 10 states instead of 8 would get you 3.322 bits per change.
And you can (arguably) push it even further - if you compress your binary signal before transmission you cram even more data-bits per signal-bit, which was a major trick of the 100+kbps modems, which often relied on compression rates as high as 4:1 to hit their advertised speeds. Of course that depends on your data being compressible - if you're transferring something that's already heavily compressed, like an .mp3 or .zip file, you'll quickly expose your modem's native bit rate.
(Score: 2, Insightful) by Anonymous Coward on Tuesday May 24 2022, @04:31AM
Baud is the symbols per second, not how many times the signal "changes per second." A symbols can be defined as any number of "changes" in the signal. For example, some autoranging systems define a symbols similar to (max, min, min, max) and (max, min, max, min), some clocked systems use reversal vs steady, and balanced systems can have over 250 "changes" for a single symbol.
(Score: 2) by sfm on Wednesday May 25 2022, @05:32PM
The info on (Bitrate != Baudrate) is reasonable, but for the Voyager case,
they are the same. Difference in bitrate and communication speed is caused
by error correction bits embedded in the stream.
(Score: 1, Insightful) by Anonymous Coward on Monday May 23 2022, @06:45PM (8 children)
Sounds like a bad data link between the AACS and the monitoring system. That kind of problem isn't easy to fix remotely, so unless they have a backup link there might not be anything they can do. Voyager 1 is a very old spacecraft. Frankly it's nothing short of amazing that anything on board still works.
(Score: 2) by Snotnose on Monday May 23 2022, @08:20PM (6 children)
But can't you just unplug it, wait 20 seconds, and plug it back in?
I don't understand the issue here.
Bad decisions, great stories
(Score: 1, Touché) by Anonymous Coward on Monday May 23 2022, @09:25PM (3 children)
If they unplug it, it will cool down to 0.0001 Kelvin. Then all conductors become superconductors, resistors stop resisting, capacitors have no capacity, transistors stop transisting, transformers stop transforming, diodes become conductors, and you're done.
(Score: 4, Informative) by Immerman on Tuesday May 24 2022, @12:56AM (2 children)
2.7K, not 0.0001K - The coldest you can passively reach in space is thermal equilibrium with the microwave background radiation. And Voyager is passing through a relatively dense particle field (by deep space standards) at high speed - that's going to heat things up further.
As for everything else... not so much. Most conductors won't become superconductors at ultra-low temperatures. Depending on capacitor design they can be almost completely unaffected by temperature. Etc.
(Score: 0) by Anonymous Coward on Tuesday May 24 2022, @05:06AM
Way to ruin the joke, party pooper.
(Score: 2) by PiMuNu on Tuesday May 24 2022, @02:12PM
However, at 2.7 K quite a few things become superconducting - Lead, Niobium, Mercury, etc
https://en.wikipedia.org/wiki/List_of_superconductors [wikipedia.org]
I always find it amazing how different things are when not on earth.
(Score: 0) by Anonymous Coward on Tuesday May 24 2022, @12:40AM
That would probably work, but the cost of sending a service tech...
(Score: 0) by Anonymous Coward on Tuesday May 24 2022, @04:34AM
Just tell their sysadmin that it will hurt their uptime somehow. They'll find a way to fix the problem, muttering to themselves the whole time about how they have to do everything.
(Score: 1) by anubi on Monday May 23 2022, @10:56PM
I'm amazed too.
Especially given all the cosmic radiation Voyager is exposed to.
The universe is hostile to computers Veritasium
DDG the above if you are curious.
"Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]
(Score: 2) by KritonK on Tuesday May 24 2022, @09:17AM (1 child)
Sounds like a fault in the AE-35 unit [fandom.com].
(Score: 2) by Joe Desertrat on Friday May 27 2022, @12:51AM
Try reversing the polarity of the neutron flow.
(Score: 1, Interesting) by Anonymous Coward on Tuesday May 24 2022, @11:56AM
It launched in 77. The gates and flops of the time had just transitioned from transistors in welded modules to medium sized ic's. Schematics should be relatively simple by today's standards.
From the symptoms it sounds like something is broken in the remote attitude monitoring. Remote control and other monitoring is still working.
Something systemic like power supply seems unlikely. Something localized like a bad gate or flop, or open or short an the interconnection.
(A short would be the worse if it brings to question another part of the circuitry which is more important.)
It will be interesting how close they can localize it by looking at the actual and expected data patterns.
A remote house call to route to a spare circuit will be impressive, if they can figure it out and if one exists.
Kind of a cool problem to solve.
It may be that Voyager has a permanent quirk just like Voger.