How NASA Repaired Voyager 1 From 15 Billion Miles Away

All through the 5 months of troubleshooting, Voyager’s floor workforce continued to obtain alerts indicating the spacecraft was nonetheless alive. However till Saturday, they lacked perception into particular particulars in regards to the standing of Voyager 1.

“It’s just about simply the way in which we left it,” Spilker mentioned. “We’re nonetheless within the preliminary phases of analyzing all the channels and taking a look at their traits. Among the temperatures went down just a little bit with this time period that is gone on, however we’re just about seeing the whole lot we had hoped for. And that is at all times excellent news.”

Relocating Code

By their investigation, Voyager’s floor workforce found {that a} single chip chargeable for storing a portion of the FDS reminiscence had stopped working, most likely because of both a cosmic ray hit or a failure of getting older {hardware}. This affected a number of the pc’s software program code.

“That took out a bit of reminiscence,” Spilker mentioned. “What they must do is relocate that code into a unique portion of the reminiscence, after which be sure that something that makes use of these codes, these subroutines, know to go to the brand new location of reminiscence, for entry and to run it.”

Solely about three % of the FDS reminiscence was corrupted by the unhealthy chip, so engineers wanted to transplant that code into one other a part of the reminiscence financial institution. However no single location is massive sufficient to carry the part of code in its entirety, NASA mentioned.

So the Voyager workforce divided the code into sections for storage somewhere else within the FDS. This wasn’t only a copy-and-paste job. Engineers wanted to switch a number of the code to ensure it can all work collectively. “Any references to the situation of that code in different elements of the FDS reminiscence wanted to be up to date as properly,” NASA mentioned in a press release.

Newer NASA missions have {hardware} and software program simulators on the bottom, the place engineers can take a look at new procedures to ensure they do no hurt after they uplink instructions to the true spacecraft. Resulting from its age, Voyager would not have any floor simulators, and far of the mission’s unique design documentation stays in paper kind and hasn’t been digitized.

“It was actually eyes-only to take a look at the code,” Spilker mentioned. “So we needed to triple examine. Everyone was trying by and ensuring we had all the hyperlinks coming collectively.”

This was simply step one in restoring Voyager 1 to full performance. “We had been fairly positive it will work, however till it really occurred, we did not know 100 % for positive,” Spilker mentioned.

“The rationale we didn’t do the whole lot in a single step is that there was a really restricted quantity of reminiscence we may discover shortly, so we prioritized one information mode (the engineering information 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 following step, to relocate the remaining three actively used science information modes, is basically the identical,” Mellstrom mentioned in a written response to Ars. “The principle distinction is the out there reminiscence constraint is now even tighter. Now we have concepts the place we may relocate the code, however we haven’t but totally assessed the choices or decided. These are the primary steps we’ll begin this week.”