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Yesterday on Dec 10 2018, NASA announced that Voyager 2 probe has exited the heliosphere - the protective bubble of particles and magnetic fields created by the Sun and entered the interstellar-medium; while Voyager 1 reached the milestone back in 2012.

With Voyager 2 has better and more science instruments, however; assume it travels at a higher speed than its current speed (17km/s) and make it to the Oort cloud before the RTGs decayed (still contactable), is it capable of proving or maybe study the Oort cloud?

The Oort cloud named after the Dutch astronomer Jan Oort, sometimes called the Öpik–Oort cloud, is a theoretical cloud of predominantly icy planetesimals proposed to surround the Sun at distances ranging from 2,000 to 200,000 AU (0.0 to 3.2 ly).

In future exploration, it states the Voyager probes will reach the Oort cloud in about 300 years and it will take about 30,000 years to pass through it. As they are still far far away from reaching the starting point of Oort cloud, are the Voyager probes still considered within The Solar System?

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    $\begingroup$ I am puzzled by the word protective. What is it supposed to protect against? And is that anymore dangerous than the solar wind itself? $\endgroup$
    – kasperd
    Commented Dec 11, 2018 at 16:34

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If you placed Voyager 1 in the Oort cloud right now, it'd be difficult to contact it (but maybe not impossible). We can barely communicate with the Voyagers now at ~140 AU using a 70 m DSN antenna. The DSN can use the VLA (one of the largest radio telescopes on Earth), that may provide enough aperture to receive the Voyagers. Calculations later.

Most of the instruments including all cameras on the Voyagers have been switched off. They've been frozen for decades. There is a chance they still work, but I wouldn't want to bet on it.

Can Voyager detect Oort cloud objects? I don't know. The Oort cloud is really dark (little sunlight), which makes detecting the Oort cloud objects difficult. And the Oort could is not a dense region, so the average distance between objects is large.

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  • $\begingroup$ If we assume the closet objects of the Oort cloud at about 1000 AE we should have DSN antennas with about 500 m diameter. But the farthest objects are expected at 100,000 AE. $\endgroup$
    – Uwe
    Commented Dec 11, 2018 at 11:40
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    $\begingroup$ I just found out the DSN can form an array with the VLA, so that gets you in the ballpark. $\endgroup$
    – Hobbes
    Commented Dec 11, 2018 at 11:46
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    $\begingroup$ The cameras were switched off because there's not enough onboard power to energize them. Voyager has no batteries and can't store power from the RTG for burst capacity to power up the cameras. $\endgroup$
    – Joshua
    Commented Dec 11, 2018 at 17:11
  • $\begingroup$ The cameras were switched off because it was no longer possible to run them concurrently with other instruments which were more likely to be useful. I don't know if there's enough power to run one of the cameras if you switched the remaining instruments off. $\endgroup$
    – Hobbes
    Commented Dec 11, 2018 at 17:41
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    $\begingroup$ Yes and no. You can probably do this even on Voyager. But when you switch an instrument off, you also switch off its heaters and the instrument drops to ambient temperature. Because materials contract at different rates when they get cold, chances are the instrument will break. $\endgroup$
    – Hobbes
    Commented Dec 12, 2018 at 7:38
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I actually see two questions here: "Is Voyager 2 capable of proving the existence of Oort cloud?" and "Are the Voyager probes still considered within The Solar System?"

(Not 100% sure on these, this is my understanding so far:)

The boundary of the Heliosphere is considered to be one of the boundaries of our solar system. The Oort cloud is already located in interstellar space. But some still define it to be part of our solar system since the cloud is still bound by the mass of our sun and planets.

So whether you consider the Voyagers to still be within the "solar system" probably depends on how you define what's part of the system. If you go by the definition "up to and including the heliopause", then the Voyagers have left our solar system.

As for the first question: the Voyager probes will run out of energy a long time before they reach the Oort cloud and we thus won't be able to detect them any more. They thus won't contribute to our understanding of the Oort cloud.

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  • $\begingroup$ I made some remarkable edits. Let's assume Voyager 2 travels with a higher speed thus make it to the Oort cloud right before it runs out of energy and still contactable. How the circumstances would be? $\endgroup$
    – not_Prince
    Commented Dec 11, 2018 at 8:20
  • $\begingroup$ It would require bigger and bigger antennas to receive data from the Voyagers since the signal is weak. So even if they would have power when they reach the cloud, it would be very, very hard (but AFAIK doable) to receive their signals. $\endgroup$
    – DarkDust
    Commented Dec 11, 2018 at 8:39
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    $\begingroup$ Given your argument, I was wondering if time has come for us humans to invest in satellites around all planets in solar system that could act like amplifier for remote voyagers and voyager like explorer future mission. There job would be to rotate around say Neptune and listen to any signal from these extra far away system and relay them back with amplified signal to earth. As a backup every planets like Jupiter, Saturn, Uranus, Neptune or even their numerous moon would need to have such satellites. So, any one satellite issue wont be an immediate issue $\endgroup$
    – Sumit Shrestha
    Commented Dec 11, 2018 at 16:37
  • $\begingroup$ @SumitShrestha: Sounds like an interesting question (would this be better than huge radio dishes on earth), please go ahead and post it. :-) $\endgroup$
    – DarkDust
    Commented Dec 11, 2018 at 17:36
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Assuming the voyager probes had enough power in their RTGs, had working instruments and could transmit data back to Earth it's still very unlikely they would be able to prove the existence of the Oort Cloud.

The instruments on the spacecraft are not designed to detect Oort Cloud objects, which are theoretically small, sparse and likely to be pretty dark objects to begin with. You'd have to get pretty lucky to spot any objects at all. Even if you saw one that doesn't prove the existence of the cloud, just that there's an object out there in the area the cloud is theorized to be. To prove the existence of the cloud you'd need to spot a few objects at least, map out their composition, position and track their orbits.

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