explain xkcd - User contributions [en]

Talk:2624: Voyager Wires

2022-05-25T20:47:28Z

Danny E. Corchado:

This is fun - assuming a pair of 14ga wires were run the 14.5 billion mile distance from Earth to Voyager 1, the mass of copper would be on the order of 10<sup>12</sup> kg, or ~5 times the mass of copper ever mined out of the earth. [[Special:Contributions/172.70.126.87|172.70.126.87]] 17:18, 25 May 2022 (UTC)
:Wow, that's a lot of copper! I wonder how they've been communicating with the probes up until now? :) [[User:Danny E. Corchado|Danny E. Corchado]] ([[User talk:Danny E. Corchado|talk]]) 20:46, 25 May 2022 (UTC)

At current prices for copper, this spool would cost ~9.6 trillion dollars. Surprisingly, that's only about a third of the US national debt. --[[User:KrazyKat|KrazyKat]] ([[User talk:KrazyKat|talk]]) 17:29, 25 May 2022 (UTC)

The problem of the Earth spinning could be solved by putting the contact at one of the poles; it will have to be on a swivel joint to prevent it from twisting. But there's also the Earth revolving around the Sun, which requires the cable length to cycle up and down by 186 million miles every year. I guess we could use a big version of dog leash holders. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 17:44, 25 May 2022 (UTC)

Days before this comic was published, NASA reported issues with Voyager 1, reporting that "the probe’s attitude articulation and control system (AACS) don’t reflect what’s actually happening onboard"
[https://www.jpl.nasa.gov/news/engineers-investigating-nasas-voyager-1-telemetry-data]

If they used wires and it was due to budget constraints, why not reel the Voyager probes back in and recycle the wire? [[Special:Contributions/108.162.245.173|108.162.245.173]] 19:24, 25 May 2022 (UTC)

Quick calc+google - world copper reserves are estimated at 870 million tonnes, Voyager 1 is 14,471,238,963 miles from Earth (Voyager 2 a bit closer, 12 x 10^9 miles)... a lot of unit conversions and simple arithmetics later... World copper reserves would be enough for a cable with about 4 mm^2 cross-section (2,3 mm diameter) for one of them or 2.3 mm^2 cross-section (1,7 mm diameter) cables to both. Someone check the math please, it's been a long day... [[Special:Contributions/172.68.110.139|172.68.110.139]] 19:31, 25 May 2022 (UTC)

This is a comic worth a What-If-article. Even with zero friction extraction systems and enough available copper, there is the problem of the speed you need to send out new wire. Voyager is moving at ca. 17 km/s and Earth moves at about 30. So when Earth and Voyager move in opposite directions you have to produce *a lot* of wire per second in order to keep up with that (not exactly 47 km/s because Voyager is moving away from the ecliptic. [[User:Kimmerin|Kimmerin]] ([[User talk:Kimmerin|talk]]) 19:53, 25 May 2022 (UTC)
:Yes, definitely worth a What If! Randall, if you read this, please write a What If article on this! [[User:Danny E. Corchado|Danny E. Corchado]] ([[User talk:Danny E. Corchado|talk]]) 20:47, 25 May 2022 (UTC)

Voyager 1 and 2 communicate with each other, or with Earth? --[[Special:Contributions/172.70.126.65|172.70.126.65]] 20:27, 25 May 2022 (UTC)

Talk:2624: Voyager Wires

2022-05-25T20:46:24Z

Danny E. Corchado:

This is fun - assuming a pair of 14ga wires were run the 14.5 billion mile distance from Earth to Voyager 1, the mass of copper would be on the order of 10<sup>12</sup> kg, or ~5 times the mass of copper ever mined out of the earth. [[Special:Contributions/172.70.126.87|172.70.126.87]] 17:18, 25 May 2022 (UTC)
:Wow, that's a lot of copper! I wonder how they've been communicating with the probes up until now? :) [[User:Danny E. Corchado|Danny E. Corchado]] ([[User talk:Danny E. Corchado|talk]]) 20:46, 25 May 2022 (UTC)

At current prices for copper, this spool would cost ~9.6 trillion dollars. Surprisingly, that's only about a third of the US national debt. --[[User:KrazyKat|KrazyKat]] ([[User talk:KrazyKat|talk]]) 17:29, 25 May 2022 (UTC)

The problem of the Earth spinning could be solved by putting the contact at one of the poles; it will have to be on a swivel joint to prevent it from twisting. But there's also the Earth revolving around the Sun, which requires the cable length to cycle up and down by 186 million miles every year. I guess we could use a big version of dog leash holders. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 17:44, 25 May 2022 (UTC)

Days before this comic was published, NASA reported issues with Voyager 1, reporting that "the probe’s attitude articulation and control system (AACS) don’t reflect what’s actually happening onboard"
[https://www.jpl.nasa.gov/news/engineers-investigating-nasas-voyager-1-telemetry-data]

If they used wires and it was due to budget constraints, why not reel the Voyager probes back in and recycle the wire? [[Special:Contributions/108.162.245.173|108.162.245.173]] 19:24, 25 May 2022 (UTC)

Quick calc+google - world copper reserves are estimated at 870 million tonnes, Voyager 1 is 14,471,238,963 miles from Earth (Voyager 2 a bit closer, 12 x 10^9 miles)... a lot of unit conversions and simple arithmetics later... World copper reserves would be enough for a cable with about 4 mm^2 cross-section (2,3 mm diameter) for one of them or 2.3 mm^2 cross-section (1,7 mm diameter) cables to both. Someone check the math please, it's been a long day... [[Special:Contributions/172.68.110.139|172.68.110.139]] 19:31, 25 May 2022 (UTC)

This is a comic worth a What-If-article. Even with zero friction extraction systems and enough available copper, there is the problem of the speed you need to send out new wire. Voyager is moving at ca. 17 km/s and Earth moves at about 30. So when Earth and Voyager move in opposite directions you have to produce *a lot* of wire per second in order to keep up with that (not exactly 47 km/s because Voyager is moving away from the ecliptic. [[User:Kimmerin|Kimmerin]] ([[User talk:Kimmerin|talk]]) 19:53, 25 May 2022 (UTC)

Voyager 1 and 2 communicate with each other, or with Earth? --[[Special:Contributions/172.70.126.65|172.70.126.65]] 20:27, 25 May 2022 (UTC)

2624: Voyager Wires

2022-05-25T20:45:18Z

Danny E. Corchado:

{{comic
| number = 2624
| date = May 25, 2022
| title = Voyager Wires
| image = voyager_wires.png
| titletext = Also, they're getting increasingly worried that someone will accidentally hit the 'retract' button, and that the end of the cable thrashing around as it winds up could devastate the Earth's surface.
}}

==Explanation==
{{incomplete|Created by a WIRE CUT BECAUSE OF BUDG- are you there houston? it's me v----ger, you'll never guess what I found! Please change this comment when editing this page. Do NOT delete this tag too soon.}}

This comic claims that the Voyager probes communicate with NASA though ridiculously long copper wires, when in reality they use radio waves.{{citation needed}} These wires would have to be continuously lengthened as the probes travel away from Earth. Supposedly, because of "high copper prices and budget constraints," they may not be able to afford to lengthen the wires much longer. If this occurred, they would have to either cut the wires or let them break, which would prevent any further communication with the probes. As mentioned earlier, however, they actually use radio waves, not long copper wires, so this will not actually happen.

If copper wires were dragged by the Voyager probes, the resulting wire would slow down the probes by drag, but be perfect space elevators for lightweight spacecraft.
Of course, since the Earth spins, the wires would also spool around the Earth, slowing the probes down even further. Clearly, this is not a good idea.{{citation needed}}

This doesn't even factor in how the Earth, in it's rotation around the sun, will drag these copper wires in a circular orbit leading the wires through the sun at least once per year. The difference between the melting point of copper and the average core temperature of the sun has not yet been established by reproducible experiment, but is believed to be incompatible with the high quality required for signal transmission.

The consequence of a cable between a craft in space and a planetary location being suddenly retracted was recently demonstrated in the first episode of the Apple TV series {{w|Foundation}}. It didn't end well for anyone.

====Alternate Explanation====
When Randall Munroe states that Voyager 1 and 2 are cabled to the Earth by copper wires, his assertion deserves serious consideration.{{citation needed}}

The primary explanation, above, takes the position that this comic is ridiculously wrong.{{citation needed}} But the insertion of several "citation needed" links suggests that the explanation's position is weak.{{citation needed}}

The comic's author, Randall Munroe,{{citation needed}} is well attested as a competent scientist,{{citation needed}} for example see the citations in the [https://en.wikipedia.org/wiki/Randall_Munroe Wikipedia Randall Munroe page]. His books, cited in that same Wikipedia article,{{citation needed}} offer well-researched easy to understand discussions of science and of everyday phenomena.{{citation needed}} Trust him.{{citation needed}}

(For completeness, see another Wikipedia article, [https://en.wikipedia.org/wiki/Disinformation Disinformation]. In its subsection ''Strategies for spreading disinformation'', strategy number 4 is "Directly Sharing Disinformation".{{citation needed}} That is mentioned here only because the top header at the xkcd web site states it is a webcomic of romance, '''sarcasm,''' math, and language.){{citation needed}}

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
[There is an image of a space probe, presumably one of NASA's Voyager probes, with a long wire connecting it to a ball, presumably earth. To the left, there is a second wire, which goes offscreen. Below, there is a caption.]

Caption: "Sad news: Due to high copper prices and budget constraints, NASA may finally have to cut the wires that they've been spooling out to communicate with Voyager 1 and 2."
{{comic discussion}}