The Expanse is well known for using hard science, and sticking closely to reality when it comes to things like gravity.

But, in Season 2, Episode 6, Paradigm Shift:

Naomi launches the protomolecule out on a torpedo on a course to the sun.

When they perform that action, their ship is not under thrust, so there should be no gravity. Yet they are moving as if there is normal gravity. They don't appear to be wearing magnetic boots either.

Was this a mistake in the show?

  • 3
    The canonical answer is that they are wearing magnetic boots. They're always wearing magnetic boots. There might still be a mistake in the scene, though – the boots should have a little light on them, showing that the magnetic soles are engaged. I'll try to fire up the episode, scrutinize it and get a screenshot.
    – tobiasvl
    Commented Mar 10, 2017 at 9:23
  • They are ALWAYS wearing magnetic boots. And Roci was docked at Tycho.
    – Petersaber
    Commented May 17, 2018 at 21:08
  • 1
    The bigger problem is that nonsense course they took around all of Jupiter's moons...
    – Harabeck
    Commented May 17, 2018 at 21:29

3 Answers 3


The ship is not under thrust as the opening shot with a total view of the ship clearly portrays. And it stays that way at least until Holden and Naomi are on board, for obvious reasons. They would get thrown off the ship, once it accelerated.

During this, Alex and Amos are in the cockpit and probably wear magnetic boots. Probably only, because

  • the boots are not visible on screen
  • the audio track misses the typical "click" sound of the magnetic boots otherwise used

So, my answer is: Yes, it's a mistake, but in the audio, not the vision part.

  • Roci was simply docked at Tycho. The station was spinning, and their ship was aligned in a way that gave the same "gravity" when they are accelerating.
    – Petersaber
    Commented May 17, 2018 at 21:14
  • 1
    @Petersaber , the rotational speed of Tycho is not enough. I estimated that it's about 1.5 degrees per second, which would give a fictive gravity of about 0.05 g. For 0.5 g, they would need 0.8 revolutions per minute, or roughly 5 degrees per second.
    – a20
    Commented May 23, 2018 at 20:20
  • @bjorn well, since everyone on Tycho easly moves around without magnetic boots turned on, either your math is off, or the visual department of the TV show made a minor mistake.
    – Petersaber
    Commented May 23, 2018 at 21:48
  • My math is not off. My estimate on the revolution frequency is off, but not by a factor 3. I doubt they made any calculations on this when they made the show.
    – a20
    Commented May 23, 2018 at 21:59

If you're talking about the scene I think you are (When Holden comes up and sees Naomi messing with the torpedo controls), when it shows the ship, it actually shows it docked at Tycho station. The station is spinning, which is where their artificial gravity comes from. They even have the ship aligned so that the spinning causes a 'gravity' that would be the same direction as when they are under thrust.

  • 3
    The ship was definitely in space - not docked. It was close to an asteroid.
    – Tim
    Commented Mar 30, 2017 at 22:43
  • 4
    No, that was the torpedo. Rocinante was docked at Tycho. I'm watching that scene right now.
    – Petersaber
    Commented May 17, 2018 at 21:10

First, we must assume that the ships are designed to have floors aligned perpendicularly (or close) to thrust vector since that's the only way getting simulated gravity from engine operation makes sense at all. Also the books seem to indicate as such since they climb ladders up/down to go for/aft. I realize I might be a bit late to this discussion...

And in the show, aren't many scenes opened by a cut of the Roci spinning around in space? Or maybe I just remember it wrong. Thinking after they make a maneuvering burn, they could use RCS to spin the ship in a way that would give sufficient centripetal force to give weak simulated gravity.

It also annoys me that there are scenes where they're constantly burning... in the book they mention things like bringing the engine down to a comfortable 0.5 g burn for convenience even though it is clearly a waste of fuel. But apparently the Epstein fusion engine is very efficient. At least with ionic propulsion engines the thrust is so low the maneuvering burns are as long as (mayb) hours or days. Dawn recently did this to reach Ceres.

  • Welcome to SFF.SE! You may want to take the tour, to get a better understanding of our site. This feels more like a general discussion of how gravity is provided in the show, rather than an actual answer regarding the specific incident mentioned.
    – RDFozz
    Commented May 17, 2018 at 21:33

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