Voyager Status, What is it? |
Voyager Status, What is it? |
Mar 14 2024, 09:22 AM
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#136
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Newbie Group: Members Posts: 19 Joined: 28-May 19 Member No.: 8607 |
I gather a bare bones version of the FDS software was loaded and thats how comms has been restored. I assume its now a case of running tests to find the faulty area of memory.
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Mar 14 2024, 04:32 PM
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#137
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Senior Member Group: Members Posts: 2542 Joined: 13-September 05 Member No.: 497 |
There's a 2022 documentary [url="https://www.imdb.com/title/tt17658964/"]about the team that's very informative. Excellent and available on Prime Video. I seem to have something in my eye... I gather a bare bones version of the FDS software was loaded and thats how comms has been restored. It's hard to tell since the blog has been so dumbed down. QUOTE This new signal resulted from a command sent to Voyager 1 on March 1. Called a “poke” by the team, the command is meant to gently prompt the FDS to try different sequences in its software package in case the issue could be resolved by going around a corrupted section. Doesn't sound like new software to me, but it might be a patch of some kind. -------------------- Disclaimer: This post is based on public information only. Any opinions are my own.
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Mar 14 2024, 06:03 PM
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#138
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Member Group: Members Posts: 931 Joined: 4-September 06 From: Boston Member No.: 1102 |
In some old computer languages, the peek command was used to read a location in memory and a poke command to write to memory. No idea if they poked some addresses in memory to program the peek into memory that was returned????
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Mar 14 2024, 06:46 PM
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#139
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Member Group: Members Posts: 447 Joined: 1-July 05 From: New York City Member No.: 424 |
Thanks Explorer1 for suggesting It's Quieter in the Twilight. It's available for streaming from PBS, and it's an interesting documentary, quite moving, as mcaplinger noted upthread.
And I now recall reading a good New York Times piece (gift link below) about the same team. QUOTE The Loyal Engineers Steering NASA’s Voyager Probes Across the Universe As the Voyager mission is winding down, so, too, are the careers of the aging explorers who expanded our sense of home in the galaxy. New York Times (Aug. 3, 2017). https://www.nytimes.com/2017/08/03/magazine...;smid=url-share The article contains a passage which I had obviously forgotten when I posted yesterday: QUOTE Unlike the astrophysicists who devise experiments for Voyager and who interpret the results, the core flight-team members don’t have the luxury of being able to work simultaneously on other missions. Over decades, the crew members who have remained have forgone promotions, the lure of nearby Silicon Valley and, more recently, retirement, to stay with the spacecraft. I wonder to what extent the team has been able to rely on additional resources outside of their team during the current crisis. |
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Mar 14 2024, 08:04 PM
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#140
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Senior Member Group: Members Posts: 1591 Joined: 14-October 05 From: Vermont Member No.: 530 |
My speculation is that the "dump memory" routine was in instruction memory that they decided to command the FDS to try. I would not guess they changed the instruction memory, because then it'd be running the program they expected, not "eureka! it's a core dump." (Commanding might simply be "start program at this instruction address" but it's not really worth clarifying that because it'll come out in time.)
As forecast on Feb 2: QUOTE In the next few weeks, Voyager's ground team plans to transmit commands for Voyager 1 to try to isolate where the suspected corrupted memory lies within the FDS computer. One of the ideas involves switching the computer to operate in different modes, such as the operating parameters the FDS used when Voyager 1 was flying by Jupiter and Saturn in 1979 and 1980. The hope among Voyager engineers is that the transition to different data modes might reveal what part of the FDS memory needs a correction. This is a lot more complicated than it might seem on the surface. For one thing, the data modes engineers might command Voyager 1 into haven't been used for 40 years or more. Nobody has thought about doing this with Voyager's flight data computer for decades. ... so what I'm speculating is that one of those "modes" had a "dump memory" routine and they didn't expect it. |
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Mar 16 2024, 12:45 AM
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#141
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Newbie Group: Members Posts: 19 Joined: 28-May 19 Member No.: 8607 |
Excellent and available on Prime Video. I seem to have something in my eye... It's hard to tell since the blog has been so dumbed down. Doesn't sound like new software to me, but it might be a patch of some kind. My comment about a new FDS software isnt from the blog article. |
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Mar 16 2024, 03:20 AM
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#142
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Senior Member Group: Members Posts: 2542 Joined: 13-September 05 Member No.: 497 |
My comment about a new FDS software isnt from the blog article. Then where is it from? -------------------- Disclaimer: This post is based on public information only. Any opinions are my own.
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Mar 20 2024, 11:50 PM
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#143
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Newbie Group: Members Posts: 19 Joined: 28-May 19 Member No.: 8607 |
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Mar 21 2024, 12:22 AM
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#144
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Senior Member Group: Members Posts: 1591 Joined: 14-October 05 From: Vermont Member No.: 530 |
Media reports of a DSN engineer having a eureka moment are a poor game of telephone in that case. But, we've seen that before. Time will tell.
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Mar 31 2024, 12:41 PM
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#145
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Newbie Group: Members Posts: 19 Joined: 28-May 19 Member No.: 8607 |
Going by the latest SFOS this looks very hopeful. FDS memory update was sent Friday. Upon the response V1 is getting close to 24hrs coverage! I'll be checking the DSN website to see if we get a data rate of 160bps (cruise mode) :-) https://voyager.jpl.nasa.gov/pdf/sfos2024pd..._04_15.sfos.pdf
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Apr 3 2024, 09:52 AM
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#146
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Newbie Group: Members Posts: 19 Joined: 28-May 19 Member No.: 8607 |
Thought I'd post an update as clearly Voyager 1 did not return to science / cruise mode following the update. I gather the update however fully restored telemetry, hence the 24hr track afterwards. This article seems to confirm it is a memory failure and they are having to rewrite / move code to avoid the failed area. https://spacenews.com/nasa-optimistic-about...mputer-problem/
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Apr 3 2024, 01:37 PM
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#147
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Senior Member Group: Members Posts: 1591 Joined: 14-October 05 From: Vermont Member No.: 530 |
This makes me wonder if the "died in 1981" side of the FDS has more working memory words in the lower region they use as instruction memory. In an earlier post, I wondered how well documented what the bad bits or words were from that 1981 failure.
That failure meant that when the FDS glitched this time, they could not just switch to the other side. (And the sides are intertwined, but there's a lower region of memory that's dedicated to the processor logic on either side, while either side can retrieve data from the upper memory of the other side) Because if the 1981 failure was also bad memory, they're now contemplating what they didn't do then... which is to rewrite the programs to avoid the bad addresses. And that makes me wonder which side is more functional now that they're both bad. |
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Apr 5 2024, 05:32 PM
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#148
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Senior Member Group: Members Posts: 1591 Joined: 14-October 05 From: Vermont Member No.: 530 |
https://blogs.nasa.gov/voyager/2024/04/04/e...ng-on-solution/
NASA suspecting entire SRAM chip is bad. Saying 3% of memory, which I suspect is 256/8192=0.03125. That might make one chip 256bytes: 2048bits, 16bit word, 128 addresses. 128x16 is what we'd call it. If it's instruction memory, that's 6% of instruction memory, but the FDS isn't processing many images these decades. |
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Apr 22 2024, 05:49 PM
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#149
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Senior Member Group: Members Posts: 2922 Joined: 14-February 06 From: Very close to the Pyrénées Mountains (France) Member No.: 682 |
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Apr 22 2024, 07:21 PM
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#150
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Senior Member Group: Members Posts: 2106 Joined: 13-February 10 From: Ontario Member No.: 5221 |
Very impressive work! Congratulations!
https://blogs.nasa.gov/voyager/2024/04/04/e...ng-on-solution/ |
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