Throughout 5 months of troubleshooting, Voyager’s floor workforce continued to obtain alerts indicating that the spacecraft was nonetheless current. However till Saturday, they lacked particular particulars about Voyager 1’s standing.
“That is just about what it was like once we left,” Spilke stated. “We’re nonetheless within the early phases of analyzing all of the pipelines and understanding their tendencies. As this era has gone on, some temperatures have dropped, however we’re seeing just about all the pieces we had been hoping for. That is at all times excellent news.
Retarget code
Via investigation, Voyager’s floor workforce found {that a} single chip liable for storing a part of the FDS reminiscence had stopped functioning, presumably as a result of cosmic ray influence or getting older {hardware} failure. This affected among the pc’s software program code.
“This deletes a portion of the reminiscence,” Spilke stated. “What they must do is relocate the code to a unique a part of reminiscence, after which be sure that something that makes use of that code, these subroutines, is aware of to go to the brand new location in reminiscence with a purpose to entry and run it.”
Solely about 3% of FDS reminiscence is broken by a foul chip, so engineers have to transplant the code to a different a part of the reminiscence financial institution. However NASA says no location is giant sufficient to accommodate a whole part of the code.
Due to this fact, the Voyager workforce divided the code into a number of elements and saved them in several areas in FDS. This isn’t only a copy and paste job. Engineers want to change some codes to ensure they work collectively. “Any references to the situation of this code elsewhere in FDS reminiscence may also have to be up to date,” NASA stated in an announcement.
NASA’s newer missions have {hardware} and software program simulators on the bottom the place engineers can check new procedures to make sure they will not trigger hurt when importing instructions to an actual spacecraft. Because of its age, Voyager doesn’t have any floor simulators, and many of the mission’s unique design paperwork are nonetheless in paper kind and haven’t but been digitized.
“Taking a look at code is admittedly simply together with your eyes,” Spilke stated. “So we needed to triple-check. Everybody was double-checking and ensuring we had all of the connections coming collectively.
That is simply step one in restoring Voyager 1 to full performance. “We’re fairly certain it should work, however we’re not one hundred pc certain till it really occurs,” Spilke stated.
“The explanation we do not do all the pieces in a single step is that the reminiscence we are able to discover shortly could be very restricted, so we prioritize one knowledge sample (the engineering knowledge sample) and solely relocate the code to revive that sample,” JPL engineer Jeff stated Jeff Mellstrom, who leads the Voyager 1 “Tiger Crew” tasked with overcoming this drawback.
“The following step is to retarget the remaining three actively used scientific knowledge modes, that are primarily the identical,” Melstrom stated in a written response to Ars. “The principle distinction is that the accessible reminiscence restrict is now extra stringent. We now have concepts the place we are able to repurpose the code, however we have not absolutely evaluated these choices or decided but. These are the primary steps we’ll take this week.