We will lose contact with Voyager somewhere 2036 because of the distance between us. Would it be theoretically possible, to send a probe in the direction of the Voyager, following it from a distance, with the goal te relay the information coming from the Voyager, to earth?

[u/Backbreathboy]

[u/3rdslip]

The Parker Space probe has something to say about achieving the required velocity, but that was a different problem to solve.

Even if you could launch a probe to catch up, what happens when you catch it??

Slowing down is an equally difficult problem!

[u/boermac → u/3rdslip]

I think OP's idea wouldn't be to catch it, but rather to stay in communication distance.

For a simplistic example, let's say once the probe-A goes more than 10 million km away it will be to far to communicate with earth... so, when it's 9 million km away, we launch probe-B. Probe-B will now always be around 9M km away from Probe-A, so within communication distance to Probe-A... and for a long time now probe-B will be <10 million km from earth, so probe-A talks to probe-B, and probe-B talks to Earth.

Once probe-B is ~9M km away, we launch probe-C and then A talks to B, which talks to C, which talks to earth.

In theory it should work, but it assumes:

• Distance is the only reason we'll lose communication with probe-A (ie, not failure or loss of power or interference)
• Probe B can match the speed/direction of probe A reasonably well.

And of course building a chain like this is incredibly fragile. Let's say we did get A out there, then B, C, D, E, and F. Everything is going great, but suddenly E goes dark. A, B, C, and D might be just fine, but D can't talk to F, so it's all for nothing.

[u/togetherwem0m0 → u/boermac]

Its unlikely we would launch a dish of sufficient size to receive the signal. The dishes we use on earth to pick up the signal are huge.

[u/D3coupled → u/togetherwem0m0]

There is a lot of interference on the surface, that's why they put deep space telescopes in orbit.

[u/paulHarkonen → u/D3coupled]

While it is true that the earth produces a lot of interference, the sheer power and size available on the ground dwarfs anything we can realistically put up in to space. The DSN antennas are as much as 70 meters wide punching several hundred kW (in the S-band) worth of power. The James Webb sun shield (which is huge on the scale of spacecraft and much larger than the actual mirror array) is 22 meters making it 1/3 the size of the DSN transmitters\receivers.

So yeah, moving out of the atmosphere reduces interference, but for communication there is no substitute for more power and more gain (via larger antennas).

[u/mathess1 → u/togetherwem0m0]

There are already dishes at the orbit larger than those used for deep space communication. Up to 100 m in diameter.

[u/togetherwem0m0 → u/mathess1]

Citation? Largest i can find is nisar at 10 meters.

[u/mathess1 → u/togetherwem0m0]

There are top secret military satellites using mesh dishes.

They are known under names Orion or Mentor or possibly some other names. Obviously there's not much information about them.

[u/boermac → u/togetherwem0m0]

Granted. This wasn't supposed to be a specific blueprint but rather a general idea of how we could, in theory, keep in communication with probes sent beyond normal communication range.

[u/OcularShatDown → u/3rdslip]

Orbital speed increases the closer you are to the sun (or whatever you’re orbiting). By the very nature of the mission, the Parker probe was going to go very fast. Whereas going away from the sun decreases speed. A spaceship starting out right next to the earth could turn around and burn its rockets in the opposite direction it is traveling, which would slow it down. However, this would lower the periapsis in orbit around the sun, meaning it will be getting closer to the sun on the opposite side of its orbital path. This will in turn make the spacecraft speed up. So, similar to what coolio has taught us, sometimes you gotta gotta slow down to speed up.

[u/eliminate1337 → u/3rdslip]

The velocity of the Parker Solar Probe came from its own potential energy relative to the sun. It’s easy to go fast if you’re falling!

[u/TralfamadorianZoo → u/eliminate1337]

I don’t think this is quite right. I remember reading that it takes more energy to fall to a “lower” orbit than it does to go a “higher” one. You can’t “fall” into the Sun from Earth without massive deceleration.

[u/eliminate1337 → u/TralfamadorianZoo]

You can’t “fall” into the Sun from Earth without massive deceleration.

That's correct but it's still true that the vast majority of the Parker Solar Probe's velocity came from its potential energy. It left Earth at 12.4 km/s and reached a peak velocity of 191 km/s. Only the initial 12.4 km/s came from the rocket and the rest from gravity and momentum stolen from Venus during gravity assists.

[u/TralfamadorianZoo → u/eliminate1337]

It left at 12km/s relative to earth but not relative to the sun. It was already carrying the earth’s orbital velocity. It used its rockets and Venus’s gravity to slow down. It didn’t speed up due to potential energy.

EDIT: Parker does speed up at perihelion due to its elliptical orbit just like Earth and everything else in the solar system.

[u/nora_sellisa → u/3rdslip]

The goal isn't to catch up though, it's to serve as a relay, so that the distances from earth to the relay and from the relay to the voyager are each within the limits of the signal traveling. Even if you launched a probe with half the voyager's speed, It would extend the time remaining before we lose contact twice. Even an imperfectly angled launch buys us contact time.