Editing Voyager 1 (section)

== Communication issues ==
In May 2022, NASA reported that ''Voyager 1'' had begun transmitting "mysterious" and "peculiar" [[Telemetry|telemetric data]] to the [[NASA Deep Space Network|Deep Space Network]] (DSN). It confirmed that the operational status of the craft remained unchanged, but that the issue stemmed from the Attitude Articulation and Control System (AACS). NASA's Jet Propulsion Laboratory published a statement on May 18, 2022, that the AACS was functional but sending invalid data.<ref>{{Cite web |last=Kooser |first=Amanda |title=NASA's Voyager 1 Space Probe From the '70s Troubled by Mysterious Glitch |url=https://www.cnet.com/science/space/nasas-voyager-1-space-probe-from-the-70s-troubled-by-mysterious-glitch/ |url-status=live |archive-url=https://web.archive.org/web/20220523190122/https://www.cnet.com/science/space/nasas-voyager-1-space-probe-from-the-70s-troubled-by-mysterious-glitch/ |archive-date=May 23, 2022 |access-date=May 24, 2022 |website=CNET |language=en}}</ref><ref>{{Cite web |title=Humanity's most distant spacecraft is sending back weird signals from beyond our solar system |url=https://www.msn.com/en-us/news/technology/humanitys-most-distant-spacecraft-is-sending-back-weird-signals-from-beyond-our-solar-system/ar-AAXDut6 |url-status=live |archive-url=https://web.archive.org/web/20220523235958/http://www.msn.com/en-us/news/technology/humanitys-most-distant-spacecraft-is-sending-back-weird-signals-from-beyond-our-solar-system/ar-AAXDut6 |archive-date=May 23, 2022 |access-date=May 24, 2022 |website=MSN |language=en-US}}</ref> 

The problem was eventually traced to the AACS sending its telemetry through a computer that had been non-operational for years, resulting in data corruption. In August 2022, NASA transmitted a command to the AACS to use another computer, which resolved the problem. An investigation into what caused the initial switch is underway, though engineers have hypothesized that the AACS had executed a bad command from another onboard computer.<ref>{{Cite news |last=Tariq Malik |date=August 30, 2022 |title=NASA solves Voyager 1 data glitch mystery, but finds another |language=en |work=Space.com |url=https://www.space.com/voyager-1-data-glitch-solved |url-status=live |access-date=September 1, 2022 |archive-url=https://web.archive.org/web/20220831232300/https://www.space.com/voyager-1-data-glitch-solved |archive-date=August 31, 2022}}</ref><ref>{{Cite web |last=Greicius |first=Tony |date=August 30, 2022 |title=Engineers Solve Data Glitch on NASA's Voyager 1 |url=https://www.nasa.gov/feature/jpl/engineers-solve-data-glitch-on-nasa-s-voyager-1 |url-status=live |archive-url=https://web.archive.org/web/20220831053515/https://www.nasa.gov/feature/jpl/engineers-solve-data-glitch-on-nasa-s-voyager-1/ |archive-date=August 31, 2022 |access-date=September 1, 2022 |website=NASA}}</ref>

''Voyager 1'' began transmitting unreadable data on November 14, 2023. On December 12, 2023, NASA announced that ''Voyager 1''{{'s}} flight data system was unable to use its telemetry modulation unit, preventing it from transmitting scientific data.<ref>{{Cite web |last=Paul |first=Andrew |date=December 14, 2023 |title=Voyager 1 is sending back bad data, but NASA is on it |url=https://www.popsci.com/science/voyager-computer-issue/ |access-date=December 15, 2023 |website=Popular Science |language=en-US |archive-date=December 22, 2023 |archive-url=https://web.archive.org/web/20231222034606/https://www.popsci.com/science/voyager-computer-issue/ |url-status=live }}</ref> On March 24, 2024, NASA announced that they had made significant progress on interpreting the data being received from the spacecraft.<ref>{{Cite web |date=March 13, 2024 |title=NASA Engineers Make Progress Toward Understanding Voyager 1 Issue – The Sun Spot |url=https://blogs.nasa.gov/sunspot/2024/03/13/nasa-engineers-make-progress-toward-understanding-voyager-1-issue/ |access-date=April 28, 2024 |website=blogs.nasa.gov |language=en-US |archive-date=May 1, 2024 |archive-url=https://web.archive.org/web/20240501122208/https://blogs.nasa.gov/sunspot/2024/03/13/nasa-engineers-make-progress-toward-understanding-voyager-1-issue/ |url-status=live }}</ref> Engineers reported in April 2024 that the failure was likely in a memory bank of the Flight Data Subsystem (FDS), one of the three onboard computer systems, probably from being struck by a high-energy particle or that it simply wore out due to age. The FDS was not communicating properly with the telemetry modulation unit (TMU), which began transmitting a repeating sequence of ones and zeros indicating that the system was in a stuck condition. After a reboot of the FDS, communications remained unusable.<ref>{{Cite web |first1=Monisha |last1=Ravisetti |date=February 6, 2024 |title=NASA's interstellar Voyager 1 spacecraft isn't doing so well – here's what we know |url=https://www.space.com/nasa-voyager-spacecraft-mission-deep-space-update |access-date=March 1, 2024 |publisher=space.com |archive-date=March 1, 2024 |archive-url=https://web.archive.org/web/20240301232621/https://www.space.com/nasa-voyager-spacecraft-mission-deep-space-update |url-status=live }}</ref> 

The probe still received commands from Earth, and was sending a carrier tone indicating it was still operational. Commands sent to alter the modulation of the tone succeeded, confirming that the probe was still responsive.<ref>{{Cite web |author1=Stephen Clark |date=February 15, 2024 |title=Humanity's most distant space probe jeopardized by computer glitch |url=https://arstechnica.com/space/2024/02/humanitys-most-distant-space-probe-jeopardized-by-computer-glitch/ |access-date=March 1, 2024 |publisher=ARS Technica |archive-date=March 1, 2024 |archive-url=https://web.archive.org/web/20240301232622/https://arstechnica.com/space/2024/02/humanitys-most-distant-space-probe-jeopardized-by-computer-glitch/ |url-status=live }}</ref> The ''Voyager'' team began developing a workaround,<ref>{{cite web |url=https://arstechnica.com/space/2024/04/the-diagnosis-is-in-bad-memory-knocked-nasas-aging-voyager-1-offline/ |title=NASA knows what knocked Voyager 1 offline, but it will take a while to fix |first=Stephen |last=Clark |publisher=Ars Technica |date=April 6, 2024 |access-date=April 6, 2024 |archive-date=April 6, 2024 |archive-url=https://web.archive.org/web/20240406130959/https://arstechnica.com/space/2024/04/the-diagnosis-is-in-bad-memory-knocked-nasas-aging-voyager-1-offline/ |url-status=live }}</ref><ref>{{Cite web |date=April 4, 2024 |title=Engineers Pinpoint Cause of Voyager 1 Issue, Are Working on Solution – Voyager |url=https://blogs.nasa.gov/voyager/2024/04/04/engineers-pinpoint-cause-of-voyager-1-issue-are-working-on-solution/ |access-date=April 13, 2024 |website=blogs.nasa.gov |language=en-US |archive-date=April 12, 2024 |archive-url=https://web.archive.org/web/20240412203857/https://blogs.nasa.gov/voyager/2024/04/04/engineers-pinpoint-cause-of-voyager-1-issue-are-working-on-solution/ |url-status=live }}</ref> and on April 20 communication of health and status was restored by rearranging code away from the defective FDS memory chip, three percent of which was corrupted beyond repair.<ref name="auto"/><ref name="CNN contact">{{Cite news |last=Strickland |first=Ashley |date=April 22, 2024 |title=Voyager 1 is sending data back to Earth for the first time in 5 months |url=https://www.cnn.com/2024/04/22/world/voyager-1-communication-issue-cause-fix-scn/index.html |access-date=April 24, 2024 |language=en |website=CNN |archive-date=April 24, 2024 |archive-url=https://web.archive.org/web/20240424020430/https://www.cnn.com/2024/04/22/world/voyager-1-communication-issue-cause-fix-scn/index.html |url-status=live }}</ref> 

Because the memory is corrupted, the code needed to be relocated, but there were no place for an extra 256 bits; the spacecraft's total memory is only 69.63 kilobytes. To make it work, the engineers deleted unused code, for example the code used to transmit the data from Jupiter, that cannot be used at the current transmission rate. All the data from the "anomaly period" is lost.<ref name="Hacking">{{cite web |last1=Rak |first1=Gwendolyn |title=How NASA is Hacking Voyager 1 Back to Life  |url=https://spectrum.ieee.org/voyager-1 |website=[[IEEE]] Spectrum |access-date=9 May 2024 |language=en}}</ref> On May 22, NASA announced that Voyager 1 "resumed returning science data from two of its four instruments", with work towards the others ongoing.<ref>{{cite web | url=https://blogs.nasa.gov/voyager/2024/05/22/voyager-1-resumes-sending-science-data-from-two-instruments/ | title=Voyager 1 Resumes Sending Science Data from Two Instruments – Voyager | date=May 22, 2024 }}</ref> On June 13, NASA confirmed that the probe returns data from all four instruments.<ref>{{Cite web|url=https://www.jpl.nasa.gov/news/voyager-1-returning-science-data-from-all-four-instruments|title=Voyager 1 Returning Science Data From All Four Instruments|website=NASA Jet Propulsion Laboratory (JPL)}}</ref>

In October 2024, the probe turned off its [[X band|X-band]] radio transmitter that was used for communications with the DSN. It was caused by the probe's fault protection system that was activated after NASA turned on one of the heaters on October 16. Fault protection system lowered the transmission rate, but the engineers were able to find the signal. Later, on October 19, the transmission stopped; the fault protection system was triggered once again and switched to the [[S band|S-band]] transmitter, that was previously used in 1981.<ref>{{cite web |last=Greicius |first=Tony |url=https://blogs.nasa.gov/voyager/2024/10/ |title=After Pause, NASA's Voyager 1 Communicating With Mission Team |publisher=NASA |date=October 28, 2024 |access-date=October 31, 2024 }}</ref> NASA reported that the team reactivated the X-band transmitter and then resumed collecting data in mid-November.<ref>{{cite web |title=NASA's Voyager 1 Resumes Regular Operations After Communications Pause |publisher=NASA |url=https://blogs.nasa.gov/voyager/2024/11/26/nasas-voyager-1-resumes-regular-operations-after-communications-pause/ |date=26 November 2024}} {{PD notice}}</ref>