sources:
NASA’s Voyager 1 Revives Backup Thrusters Before Command Pause - NASA Science,
https://skyandtelescope.org/astronomy-news/voyager-1-fires-dormant-thrusters-in-deep-space/
The space kids and our remarkable "V'Gers".
This time Voyager 1 (and by association its twin "brother" Voyager 2). The NASA article at the link explains it. A lot going on, so you might need to read a couple sections more than once.
Voyagers have always needed to point their high-gain antennas (that's the big parabolic one) AT the earth. Ground based antennas are used to get signals/data FROM, and send signals/data TO, each spacecraft.
As the V'Gers did their thing flying around the solar system, the orientation of their antennas relative to the earth would obviously change. The spacecraft uses "thrusters" to reorient them (pitch and roll - so left, right, up, down)) as needed.
In 2004, the primary thrusters on Voyager 1 stopped working (
27 years after launch), so NASA started using the "backup" thruster system to control orientation.
Now, the backup thruster system (
21 years later) on V'Ger 1 is about to fail.
Against that backdrop, the
ONLY (out of the three sites they use to track the spacecraft) ground-based antenna STRONG enough (given how far away the spacecraft are now) to get signals/data TO the spacecraft, is about to
go offline for upgrades/maintenance.
Boil all that down, the spacekids decided to try to get the PRIMARY thrusters working again
(21 years after failing) BEFORE the backup system possibly fails. If neither system remained active, NO reorientations, therefore NO communications, with V'Ger 1 would be possible.
With some ingenuity, foresight, and big, brass ones, the space kids got the primary thruster system to work. The high points of how they did it are described in the link above.
Remarkable feat, in a series of death-defying heroics as these spacecraft approach
50 years old (they were only supposed to last five years), and 15+ billion miles away.
One thing I dont get?
What is causing spacecraft orientation to change as it now streaks through intergalactic space?
I guess its just as simple as EVERYTHING in the universe is still moving (earth around the sun, the solar system position IN the Milky Way, Milky Way itself spinning around its black hole, the effects of all that ON the spacecraft, etc).
All that complex cosmic dancing, in turn, MIGHT require the space kids to reorient the antennas? Maybe its something else?