Few points: It doesn't need fuel to move, it's just coasting in empty space. For power, it uses decaying plutonium. The heat generated by that is converted to electricity by a thermoelectric generator.
There are small compressed gas thrusters to 'turn' the probe if needed. But as it is, the main antenna was pointed towards earth a while ago and since it's so far away, the angle between earth and the probe changes really slowly (think of seeing a mountain off the side of the highway and how long it takes to drive to a different angle of it).
Space is incredibly empty. Like 99.99999999999999999% empty. Remember Jupiter is absolutely massive, but from Earth it is only blocking a tiny tiny portion of space behind it from our position.
The signal from Voyager doesn't have to be laser-aligned to reach us. Then antenna on Voyager is probably about 5degrees wide. (Like shouting with your hand making a circle around your mouth). The signal is super weak but we can pick it up with multiple gigantic sensitive 100foot wide antenna dishes on Earth.
[T]he main antenna was pointed towards earth a while ago and since it's so far away, the angle between earth and the probe changes really slowly ...
Technical nit: the antenna does have to be re-pointed to Earth sometimes. Instrument calibration rolls and such performed by the spacecraft require readjustments of its attitude before transmitting back to Earth. Is the 2 AU-wide orbit of the Earth around the Sun no longer a factor given the 5-degree widening of the radio signal at Voyager's current distance?
(The 70-meter dishes are 230-feet wide - about 3/4 the length of an American football field!)
I was wrong its 0.5degrees beamwidth. Still huge at this distance of course, but relatively speaking.
Regarding pointing, I was thinking of how the probe is programmed to 'autonomously reset' its overall pointing a few times a year. The attitude thrusters are still pulsing on daily frequency making minor corrections (and it's actually because their minimum pulse is too long to more cleanly counteract the inertia).
I'm sure I'm not entirely correct, but it's fueled by a reactor that runs off the heat from plutonium decay. As for the signal - space is REALLY empty. Amazingly, stunningly empty.
a small nuclear reactor, and it's been shutting things off to keep the power going... I think.
and constant reattempts every 24 hrs or so? I'm not sure about that part... plus, imagine space is huge, the likely hood of something being in the way could potentially be super small... like almost nothing.
The signal isn't obstructed by objects because of how sparse space is. Asteroid fields aren't like what you see in movies, sure there are a lot of them but the space they occupy is immense and they're very far between
They don't need to point exactly at the dishes on Earth either, the beam they send is 2.3° degrees wide. By the time it reaches the Earth we're getting hit by a radio wave that's nearly a billion(!) km wide in the case of Voyager 2
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u/SufferDieoxide Dec 11 '24
Dumb question - how is Voyager 'fueled'? It has been out there for more than 40 years. What is its source of energy to do all of these activities?
And, how did the signals travel to exact coordinates in Earth without getting physically blocked by some object in space - like a massive asteroid?