All the way through the 5 months of troubleshooting, Voyager’s floor workforce endured to obtain alerts indicating the spacecraft used to be nonetheless alive. However till Saturday, they lacked perception into explicit information about the standing of Voyager 1.
“It’s just about simply the best way we left it,” Spilker mentioned. “We are nonetheless within the preliminary levels of inspecting all the channels and having a look at their traits. One of the crucial temperatures went down a bit of bit with this time period that is long gone on, however we are just about seeing the whole thing we had was hoping for. And that’s the reason at all times excellent information.”
Relocating Code
Via their investigation, Voyager’s floor workforce found out {that a} unmarried chip liable for storing a portion of the FDS reminiscence had stopped running, most definitely because of both a cosmic ray hit or a failure of getting old {hardware}. This affected one of the vital laptop’s instrument code.
“That took out a piece of reminiscence,” Spilker mentioned. “What they’ve to do is relocate that code into a distinct portion of the reminiscence, after which ensure that the rest that makes use of the ones codes, the ones subroutines, know to visit the brand new location of reminiscence, for get right of entry to and to run it.”
Most effective about 3 p.c of the FDS reminiscence used to be corrupted via the dangerous chip, so engineers had to transplant that code into any other a part of the reminiscence financial institution. However no unmarried location is big sufficient to carry the phase of code in its entirety, NASA mentioned.
So the Voyager workforce divided the code into sections for garage somewhere else within the FDS. This wasn’t only a copy-and-paste activity. Engineers had to alter one of the vital code to ensure it’s going to all paintings in combination. “Any references to the site of that code in different portions of the FDS reminiscence had to be up to date as neatly,” NASA mentioned in a observation.
More moderen NASA missions have {hardware} and instrument simulators at the floor, the place engineers can take a look at new procedures to ensure they do no hurt after they uplink instructions to the actual spacecraft. Because of its age, Voyager does not have any floor simulators, and far of the venture’s authentic design documentation stays in paper shape and hasn’t been digitized.
“It used to be in reality eyes-only to have a look at the code,” Spilker mentioned. “So we needed to triple take a look at. Everyone used to be having a look via and ensuring we had all the hyperlinks coming in combination.”
This used to be simply step one in restoring Voyager 1 to complete capability. “We had been lovely certain it might paintings, however till it in truth came about, we did not know one hundred pc evidently,” Spilker mentioned.
“The rationale we didn’t do the whole thing in a single step is that there used to be an overly restricted quantity of reminiscence lets in finding temporarily, so we prioritized one knowledge mode (the engineering knowledge mode), and relocated solely the code to revive that mode,” mentioned Jeff Mellstrom, a JPL engineer who leads the Voyager 1 “tiger workforce” tasked with overcoming this downside.
“The next move, to relocate the remainder 3 actively used science knowledge modes, is basically the similar,” Mellstrom mentioned in a written reaction to Ars. “The primary distinction is the to be had reminiscence constraint is now even tighter. We’ve concepts the place lets relocate the code, however we haven’t but totally assessed the choices or decided. Those are the primary steps we will be able to get started this week.”
