zlacker

Not a rocket scientist; but I have tuned in a TV. I imagine it is simply programed to turn a few degrees then turn back to wherever it saw the strongest signal from earth.

>>ZiiS+(OP)
Makes sense.

So I presume it uses its thrusters to impart a very small spin on one axis, and then on an orthogonal axis.

A mechanism records the signal strength as it sweeps all angles, and once the optimum direction is determined, the thrusters are fired in just the right way to counteract the spin and bring the craft to a halt at the optimum orientation.

Given this was programmed decades ago - the electromechanical system that does all this jugglery and runs reliably for so long would be a great case study for systems design.

Even the programming that ensures that this routine is triggered without fail every few months must also have gone through intense reliability testing.

>>albert+02
doesn't even need thrusters if it has reaction wheels that are still operational

>>ZiiS+(OP)
But....How does it know it's the earth?

It is billions km away.., is the earth that noisy compare to solar wind and cosmic rays?

>>j16sdi+il
Voyager has a star sensor that is meant to align with the Sun and Canopus (IIRC). If both are properly aligned it means it's pointed in the right direction. At its current distance the beam width is wide enough to cover all of Earth's orbit. So really it just needs to point at the Sun anymore.

The carrier signal from Earth is also powerful on a particular frequency and polarization. While there's definitely noise at the receiver it's looking for a very specific signal so can filter out everything it's not expecting. We do the same thing on the Earth side, filtering out noise to recover the very weak signal received from Voyager.