In Nemesis Games during the battle a character moves through the ship. Since the ship is maneuvering they get banged around a lot. My books are written with a tech level similar to the Expanse so this scenario is useful. I am assuming, please tell me if I’m wrong, that spacecraft will be taking lots of damage some of which could be easily repaired by the crew. But here are the problems:

  1. The ship will make sudden and intense accelerations at high G to evade and close with the enemy.
  2. Maneuvers will rarely only go along the axis of the ship. Up down and left right movements are expected.
  3. The ship being hit by high speed projectiles (railguns) or hit by missiles will cause abrupt motions especially if the ship is accelerating.
  4. All of these will cause any crew no strapped in and drugged to be flung around and severely injured by high G. I.e. going down the ladder in a 0.3 G burn when all of a sudden a 12 G acceleration throws them off and they die. Or they are floating through a corridor when the ship moves violently right and they are slammed into the wall possibly injuring them.

It would be really dumb to not be able to use a gun system because feed is snapped and could be simply welded back. So the question: How can my crew preform simple and critical repairs during maneuvers in battle? Any solution must be functional and not negatively impact performance.

  • $\begingroup$ Why won't the maneuvers be along the axis of the ship? Don't the engines of the ship push along the axis? Or are you operating in atmosphere? $\endgroup$
    – Mathaddict
    Jan 8, 2021 at 18:51
  • $\begingroup$ Well in space the main drive can’t turn me. Soooo I use maneuvering thrusters that are along the sides. Now I can turn whichever direction I want. $\endgroup$
    – 11Bravo
    Jan 8, 2021 at 18:52
  • 3
    $\begingroup$ But the maneuvering thrusters don't produce high G forces, just the main engines right? So the high G forces are still going to be along the axis. $\endgroup$
    – Mathaddict
    Jan 8, 2021 at 18:53
  • 2
    $\begingroup$ That's going to be a really fast turn and really big thrusters if you even want to get 0.5 g in an odd direction. $\endgroup$
    – Mathaddict
    Jan 8, 2021 at 18:57
  • 1
    $\begingroup$ I would have to wonder whether any parallels can be drawn from combat operations on modern (WW2 and onward) navies - and whether they have policies of not attempting any significant non-critical-emergency repairs during combat. I imagine there are a lot of tools for which you wouldn't want to be even slightly jostled while using (such as a welding torch). $\endgroup$ Jan 8, 2021 at 20:01

2 Answers 2


A tricky, high dexterity task with random 12G thrusts? Forget it.

The issue isn't so much the G LOAD, it's the random and rapidly changing nature of it. Hot welding slag, in a vacuum (as your hull was likely breached by the railguns) so not cooling much, randomly accelerating at 12g, or 115m/s/s, is probably going to be as lethal as a railgun round. A simple spanner ripped out of someone's hand would plausibly either penetrate the hull in a 12G manoeuvre, or come back and kill the engineer or obliterate the repair robot.

If your gun feed is damaged and needs welding, retreat for repairs. The close-in railgun fight at high G is a last resort when you're out of missiles and can't run away or they've caught up with you. I can't remember the exact quote from "The Expanse", but it was something to the effect of "CQB - we're dead. CQB? Oh that's close quarters battle. Railguns at close range. We never want to do this cause the chance of making it out is so low, basically its a fight to the death."

Ignoring all that - can this actually be done?

Perhaps - remove the "random" and you've got a chance.

With plausible near future tech I believe we could build a robot to do simple repairs under a steady high G load - the known, constant acceleration direction would factor into the repair. The robot could orientate the welder, itself, and protective panels in such a way that the slag is contained and no parts fall loose.

This is a huge AI / robotics project in itself even in the constant acceleration use case.

With such tech further refined, it may be possible for the flight computer to send a few milliseconds advance notice of its manoeuvres to all robots. This could allow the robot to either re-orient or secure its workspace and brace for acceleration before the rapid force is applied.

The downside of this is that your manoeuvrability is delayed by a about a hundred milliseconds. Your engines are unlikely to be able to spool up from 0 to 12gs in under 100ms so this may be a non-issue.

A network connection between the repair robot and the flight computer could also do a "synchronised dance" of the mutual interconnected tasks of a space fight and a repair. The ship dodges a salvo, then the robot gets in position and secures itself, then the ship starts a rotation, then the robot opens the outer panel and secures it, then the rotation stops, then the robot removes the damaged part, then then main engines fire, etc.

Certain G accelerations may be useful to aid in the repair - I've struggled to repair things and could certainly use a 12G force helping out. If the ship needs to side thrust any direction to dodge a salvo, and the actual direction doesn't matter, and if it moves left it'll help the robot pull out a stuck part, might as well thrust left.

  • 3
    $\begingroup$ I think it could be boiled down to: Any issue a human could quickly fix with a "patch job" could be done better by a near-future robot or smart damage control/redundancy systems. Any issue too complex for a robot or an automated systems couldn't be fixed by a human mid-combat anyways, so it's a moot point--they'll just need to deal until they can retreat or the fight is over. $\endgroup$
    – Dragongeek
    Jan 8, 2021 at 23:17


I was watching a scene from the Expanse just recently. What a fine example of the perils of high G maneuvers!


If you had on an exosuit instead of a space suit that would be great. Many reasons

1: Exosuit accelerometer can detect sudden change before you move, and firm up to counter the move. You will be pressed against the inside of your suit, not thrown.

2: Exosuit mitts / boots will not let go of supports because they are weak. You have to tell them to which only would be the case if you were like the badass earth dude in that scene from Expanse.

  1. Exosuit has peristaltic internal waves from feet on up to get blood back to heart - kind of like MAST trousers but alive. It feels nice. You can use it in regular gravity if you want to.

  2. Needless to say exosuit provides O2 and not from some stupid hose! You got a little onboard and a rebreather to scrub CO2.

  3. Exosuit has a limited automatic maneuvering jet because if you are drifting in 0G and suddenly you are at 10G you will traumatically stop drifting. Automatic jet moves drifting suit wearer to nearest substrate and latches on.

  4. Exosuit smells weird on the inside. That is not a feature, just how it always turns out.


You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .