How is it possible to still be able to get a signal from a spacecraft that's so far away? How can the antenna be directional enough while still being pointed right at the Earth? How do we remove the noise?
Voyager 1 has a large 12-foot diameter directional radio antenna that it keeps pointed at Earth. If you look at photos of Voyager, the antenna (the big dish) basically is most of what you see: it's bigger than everything else on craft.
There are radio antennas across the Earth listening to its very weak signal.
Signal processing algorithms can pull out a signal from well below the noise floor these days. Even the small and nondirectional antennas on your phone are good enough to receive GPS signals even all the way down at -125 dBm, which is WAY less than your phone receives in interference from random radio stations and faulty LED bulbs nearby.
The tech used to receive Voyager signals is not really different, just more sensitive and sophisticated (and expensive).
I think that would fall under the "must accept interference" portion of FCC Part 15, my phone communicating back to the tower might raise some alarms if I tried amplifying it at all though!
Because their power supply is shitty and it's easy to transform the chopper that is used in the switching power supply to behave as an oscillator instead, which will start to emit harmonics (https://en.wikipedia.org/wiki/Switched-mode_power_supply)
Electromagnetic radiation power roughly equivalent to the amount of light they output. I wished I was kidding, some of them are so bad they should qualify as jammers.
A ridiculously huge and powerful array of antennas spread across the planet.
NASA has a dashboard online for the Deep Space Network and you can see live which spacecraft we're communicating with. The Voyagers are usually active any time I look.
According to the article, they can send commands to Voyager 1, and it executes them, and it is still sending data back - the problem is the data coming back is gibberish (repeated patterns of 0s and 1s). They are still hoping they can work out a sequence of commands to reset its computers and resolve the problem. So it makes sense the DSN is currently talking to it.
For me, it looks like it computer damaged by interstellar radiation, which is much more energetic than solar radiation, so it's unlikely that reset will help.
According to NASA's blog [0] they believe the problem is between the FDS computer and the TMU (the outbound radio modulator). The other two onboard computer systems, CCS and AACS, they believe are still working. All three systems are dual redundant pairs of computers. So, even if one FDS was damaged, in theory they should be able to switch to the other. The blog post is vague on what exactly they tried - "the team tried to restart the FDS and return it to the state it was in before the issue began, but the spacecraft still isn’t returning useable data" - so I don't think we can rule out there are other things they can still try.
MITM attack?
Well they won't get away with this! Some humans are super-intelligent - they already discovered that the Earth is flat, and sitting on the bank of a giant turtle (yes it's turtles all the way down)
