The Expanse : totally bogus interplanetary navigation…

I am watching episode 1.2. I can't help noticing the totally bogus interplanetary navigation.

The ice mining ship Canterbury was heading back to Ceres the largest asteroid.

Hoss and four other crew members are dispatched in a lifeboat, to investigate a derelict vessel. When they run into trouble they look to try to make it to "Ganymede Station".

Ganymede is a large moon of Jupiter. Ceres orbit doesn't come near Jupiter, but, even if it did, Ganymede is a very bad choice of destination. Jupiter is the deepest gravity well in the Solar System, which makes travel to an from its moons very energy intensive.

How long does it take for travel within the belt? Canterbury seemed to be in free fall, on a ballistic orbit. That would imply voyages lasting multiple years.

When Canterbury responds to the distress signal they don't head all the way to the derelict ship. They have enough fuel to go most of the way, and the lifeboat is dispatched to go the remainder of the distance. I think it is implied they don't have the fuel to get to Ceres by themselves, let alone anywhere else.

In episode 1.1 a character says something like, "I thought there were no other ships within three million klicks of us". The moon is about 350,000 kilometers from earth, less than 1.5 lightseconds.

In episode 1.2 they say something about their rescue ship coming within 80,000 kilometers.

Jupiter is almost 8,000,000,000 kilometers from the Sun. Ceres a little more than half that.

Updated: added 3 zeroes, as below.

I suggest you go rewatch episode 1 and take note of the gas giant with all of the rings that the Canterbury is orbiting before heading back to Ceres.

"Jupiter is almost 8,000,000 kilometers from the Sun"

No, more like 800,000,000 km, unless Jupiter is about to crash into the Sun and no one told me. Hell, Mercury in 50,000,000 km from the Sun.

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I suggest you go rewatch episode 1 and take note of the gas giant with all of the rings that the Canterbury is orbiting before heading back to Ceres.

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Yeah, I multi-task, listen to the TV, while working on my computer, and rewinding if I hear something that makes me think I need to look at the screen.

I know Isaac Asimov's terrific story The Martian Way was an early and influential story that had colonies mining Saturn's rings for water. But surely, energy-wise, it would be cheaper to mine icy asteroids? Icy asteroid belt asteroids are both closer to Mars, Ceres, Eros, etc, but there is no gravity well to descend, and then ascend.

You are correct I dropped zeroes.

Well the fuzzy math and fuel supply they use have been talked about at times here. Not sure if you've seen the entire season, but there are some maneuvers in space that also come into question. I'm OK with everything not being totally accurate or probable though.

The Canterbury was heading to Ceres from Saturn. We dont know exactly where they were when they were destroyed. We only know that the Donnager was the martian Jupiter fleet flagship and they were sent to investigate the destruction of the Cant. So they could be nearer to Jupiter than Ceres. And thats why they were thinking of going to Ganymede.

The Canterbury is getting its water from Saturn's rings, as it can just scoop it up in ice form, instead of mining carbonaceous asteroids and trying to extract the ice from the frozen rock slurry that passes for their mantle. I.e., the Cant isn't a mining vessel, it's just a "hauler."

Ships in the Expanse use something called the Epstein drive, one of the few outright magical pieces of tech in the series (at least on the human side). It's described as some sort of fusion pulse drive, but its efficiency is through the roof. Basically, it can push Gs in the double digits for hours and a steady 1G or so for days or weeks, so every single location in the Solar System can be reached in a matter of weeks in the inner system, or months for the outer.

The Canterbury didn't lack fuel, they were accelerating towards Ceres when they had to alter their course to match the Scopuli's. All that meant was they would miss their deadline and forego a bonus.

Ganymede was mentioned since it's one of the first large human settlements in the outer system, a heavily populated, Earth-aligned agricultural colony and, effectively, the "granary" of the Belt. If they were returning from Saturn, it's possible that it just happens that Jupiter was close by on their way back.

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Ganymede is a large moon of Jupiter. Ceres orbit doesn't come near Jupiter, but, even if it did, Ganymede is a very bad choice of destination. Jupiter is the deepest gravity well in the Solar System, which makes travel to an from its moons very energy intensive.

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Which the star ships in this universe dont have to care about at all, because they are vastly superior to what we have today and can give you extreme accelerations of 30g over extended periods of time (I dont remember it qualified for how long, though it possibly was), which apparently with certain drugs people can actually survive (in reallife this kind of acceleration would be a death sentence, about 25g for a couple seconds is the maximum the human body can handle, and maybe 9g for a longer time), and 1g over days of time.

Basically a star ship starts somewhere, continously accelerates until the middle of the journey, turns around, and then deaccelerates for the rest of the journey.

Compared to that, the gravity well of Jupiter is nothing short of a complete joke.

Thats also why all star ships on maps basically travel on a straight line.


A gentleman will not insult me, and no man not a gentleman can insult me.

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Ganymede is a large moon of Jupiter

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Which the star ships in this universe dont have to care about at all

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Starships? You mean fictional starships? I wrote this after watching a couple of episodes, and saw nothing to indicate the ships we were seeing were starships, even sublight starships.

I am at episode 1.7 or 1.8. No starships yet.

So, I think my observations remain valid.

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Basically a star ship starts somewhere, continously accelerates until the middle of the journey, turns around, and then deaccelerates for the rest of the journey.

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This only applies for the "cruise" part of the journey when you're travelling in a straight line however our sun's gravity is constantly acting on any ship in our solar system and travelling between multiple planets/moons means it will spend a significant amount of time navigating gravity wells.

Also, there are no starships designed to travel between stars in The Expanse. You're confusing Interstellar travel with Interplanetary travel.

https://en.wikipedia.org/wiki/Interplanetary_spaceflight

Jupiter is the 2nd deepest gravity well in the solar system. The distance from Ceres to Jupiter depends on where they are in their orbits.

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Jupiter is the 2nd deepest gravity well in the solar system. The distance from Ceres to Jupiter depends on where they are in their orbits.

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No. Around our sun, Sol, there is a gravity well we call the Solar system. The Solar system contains smaller gravity wells, of which Jupiter's is the largest, Saturn's the 2nd largest, and so on.

Oh hi, we never did get this straightened out did we? What was the deepest gravity well in the solar system again? If you could be really condescending about it again that would be great.

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The distance from Ceres to Jupiter depends on where they are in their orbits.

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Duh!

I said they never get close. Jupiter's orbit puts it about 5 AU from the sun. Ceres orbit puts it 3-4 AU from the sun. So their distance varies from about 8 AU to 1 AU.

I said they never get close, and 1 AU is not close.

I'm definitely no expert, but in terms of interplanetary travel on this show, it's simply gonna have to do. Especially when Earth and Mars argue and fight over control and independence. Not a lot between Mars and Jupiter except Ceres. Ceres isn't always that close to Mars either, especially in proximity to an Earth that definitely doesn't want newly formed Martians running everything. And there is some free enterprise out there too, which makes even veering farther out, while even more dangerous, worth it. It's a fantasy show and isn't necessarily supposed to be real life, but in the minds of most real time astronomers and space experts, Ceres really is considered prime real estate, as are some of the moons of Saturn.

They're as close as any two bodies in our solar system that are in different orbits. So:

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Ceres orbit doesn't come near Jupiter

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Means virtually nothing if you move the goal posts like this. It's the same as saying Earth's orbit doesn't come near Mars', Mars' orbit doesn't come near Ceres', and so on. All true, in the sense you seem to mean. Following your logic anyplace in the solar system is a bad choice of destination and so any show with interplanetary travel is bogus science.

The deepest gravity well in our solar system is the sun.

We all know that, even the fanboys of this show knows that but they are in denial.

Fanboys are inventing all excuses to justify this irrational traveling in the solar system.

This show is clearly oriented for people with low IQ, educated people will immediately notice at least 200 flaws.

Hope they fire the writer, fix the show.

It's not a documentary, so no need to fix anything far as I'm concerned.

It's a fictional show, the writers can do whatever they want. There's nothing in the fictional writer's guide that says, they must be factual in everything they write. Plus, name some shows that don't have flaws.