/dev/mull

Voyager 1 Resumes Sending Science Data from Two Instruments

the two instruments being the magnetometer and the plasma wave subsystem. the two particle instruments, the cosmic ray instrument and the low-energy particle instrument, are still offline.

my semi-informed guess is that the voyager team started with the lowest-bandwidth instruments: the plasma wave dealie generates only 32 bits/second, and the magnetometer gathers 120 bits/second. the particle detectors' description makes it sound like they produce particle spectra (lists of how many particles and what energies they had) which could be a lot of data, relatively speaking.

Engineers Pinpoint Cause of Voyager 1 Issue, Are Working on Solution

Engineers have confirmed that a small portion of corrupted memory in one of the computers aboard NASA’s Voyager 1 has been causing the spacecraft to send unreadable science and engineering data to Earth since last November. Called the flight data subsystem (FDS), the computer is responsible for packaging the probe’s science and engineering data before [they're radioed back to Earth].

[...]Using [a core dump], the team has confirmed that about 3% of the FDS memory has been corrupted, preventing the computer from carrying out normal operations.

The team suspects that a single chip responsible for storing part of the affected portion of the FDS memory isn’t working.[...]

Said single chip holds 256 16-bit words of memory, out of the vast 8k in that FDS. (The Voyagers each have two FDSs, but the other one on Voyager 1 failed in the 1980s.)

High geekery: had the engineers asked for a memory dump of Voyager 1's main computers, it would have been a literal core dump, since the machines are old enough to have actual magnetic-core memories.

Anyway, I expect the clever folks at JPL will manage to get V1 more working again soonish.

click here, which will take you to a post in a thread discussing juno's latest io close pass.

click on the thumbnail, which will bring up a ~3500px X 900px image of the limb of io. this is the best image of io we've ever gotten.

admire! awe! wonder!

this is the most amazement i've gotten from space exploration since the voyager neptune fly-by.

it's 45 years old today.

the voyager missions were some of the defining cool science achievements of my youth to early adulthood. before them, we knew next to nothing about the outer solar system. pioneers 10 and 11 flew by jupiter and saturn (pioneer 11 only), bringing back some pretty pictures and some data, but they were extremely primitive machines, barely brighter than traffic lights. they were programmable in the same sense modern traffic lights are: mission control could turn different instruments on and off by remote control, and change the spacecrafts' orientation, but not much more.

the voyagers were a bit smarter -- each as bright as several intersections' worth of traffic lights -- carried a ton more instruments, but most importantly, flew much bolder missions, the pioneers having shown that they were possible.

they brought us back the first real information on the moons of outer planets (io has volcanoes! enceladus has geysers! titan has a really funky atmosphere! triton has geysers!) and everything we know about uranus and neptune. and they delivered that over about a decade of steady discoveries.

voyager 2's neptune encounter remains my favorite part of the mission. the flyby was about a week before the 47th worldcon (noreastcon 3) and the con had a panel discussion on the hot new data, some of which was just being released to the public. a group of science fiction authors, actual rocket scientists from MIT, and a few other luminaries tried to describe what we were seeing, which frankly nobody understood (and some of which which we still don't understand). that's one of the neatest events of my life, watching science as it was being done.

the voyagers are still going strong, plowing through interstellar space, gathering data. if they can last until 2027 -- 50 years after launch -- they'll be the first to last that long while still operating. voyager 2 is already the longest-lived space probe. voyager 1 is more likely to last that long; for mysterious reasons, its radioisotope power supply is a holding up a bit better. i'm eager to see if that happens.