The setting.
Space, the inner asteroid belt. An LNCHR ship is anchored to an asteroid without atmosphere.
A LNCHR ship is a ship with two main facilities:

  • A space crane to raise the slugs filled with minerals from the mining station depots on the asteroid.
  • A massive rail gun to launch the slugs to their destination

The slugs themselves are standardized in size and weight meaning that different compartments are going to be filled with minerals of different density.
Slugs properties:

  • radius: 2 meters
  • length: 8 meters
  • mass when filled: 220 tons approx.

The railgun achieves hurling slugs at 5km/s at the muzzle

For additional details on the asteroid see here. They are quite beside the current question though.

The question.
Mr. Y is a man of character. He knows how to get his way. Now that means standing right next to the muzzle of the massive railgun. Which is loaded and ready to launch.
He is in space and wearing an extra vehicular activity suit that allows him good freedom of movement. It is not designed to work outside for long hours.
The railgun is activated and the massive slug passes less than a meter to his side.
What happens to Mr. Y?
I assume there won't be any shockwave
Will he be fried / electrocuted? I have no idea if / how an electromagnetic field will form at the muzzle in space. No idea too if it would be strong enough to damage Mr. Y directly or his suit.
What would be the main hazard for Mr. Y?

The suit is not specifically designed to resist strong electromagnetic fields. It is designed to allow staying outside for a limited period of time (2 hours tops) checking the work of others. Mr. Y does not do. He makes do.

Further details:
The railgun is powered by generators along its body. They don't leak harmful radiation.
The railgun has already been activated several times before the fatal (?) shot. It's designed to shoot once every 20 minutes. The time is needed to load the slug properly, run checks and prepare it for launch
The railgun is cleared of dust that could come from the asteroid
Before launch operations start the crane is lifted and the anchors removed
The LNCHR is capable of readjusting after each shot to send the slugs along a correct trajectory The LNCHR orbits the asteroid above the equator while loading. Typically depots are built in this area to facilitate the loading process

  • $\begingroup$ How long is the railgun? How much ferrous material is in Mr Y's spacesuit (ignoring iron in red blood cells etc)? $\endgroup$ Jan 11, 2022 at 1:31
  • $\begingroup$ @KerrAvon2055 Quite frankly I have no idea about the length of the railgun and was hoping of getting away with it without stating it in the story. As long as necessary to make the slug reach 5km/s at the muzzle :) $\endgroup$ Jan 11, 2022 at 1:35
  • $\begingroup$ @KerrAvon2055 Also no idea of the amount of ferrous materials in a normal space suit. Even less about Mr. Y's. I would say less than a standard EVA suit we use nowadays as they are made to work outside for hours (even a toilet is included!) $\endgroup$ Jan 11, 2022 at 1:39
  • $\begingroup$ Put it this way - an extremely strong magnetic field is being created sequentially at successive points along the railgun in order to accelerate the projectile. The shorter the railgun, the more intense the field will be at each point in order to achieve the 5km/s velocity required. The amount of ferrous material in Mr Y's suit will determine what force will be slamming him into the nearest section of the railgun. So both railgun length and ferrous material content are needed to give an answer. (Hint: Magnetic soles / palm pads would be bad) $\endgroup$ Jan 11, 2022 at 2:01
  • $\begingroup$ I know railguns are trendy and all but if a 220t payload is being accelerated to 5 km/s, the current being supplied is so extreme that one would expect molten bits of the rail to be ejected along with the payload since current is passed through the payload using direct physical contact with both rails or, for plasma armature based railguns, a significant blast of plasma from the armature material. Both result in, shall we say, unfortunate effects on Mr. Y. Use a linear motor / coilgun system like en.wikipedia.org/wiki/StarTram instead. $\endgroup$ Jan 11, 2022 at 2:03

1 Answer 1


I am going to go with my last point in my comments as an answer, in a very non-elegant but very realistic, universally typical, death scenario.

The kickback.

As the 220 ton shot is propelled, Newton's Laws dictate that the launcher will recoil backwards. There will, of course, be dampers and strain relief methods built in to the structure. Thus, the huge muzzle will first retreat backwards from its resting position, just behind his body, and then just as quickly recoil forward as the strain relief 'springs' and dampers return their energy. If he were in front of, but to the side of, the muzzle, he would learn the lesson everyone learns when firing a high powered weapon - the recoil really, really hurts. The end of the muzzle would suddenly be in the same place at the same time as his body, as the muzzle returns to firing position, with an unpreventable over-shoot as it oscillates back and forward until the energy is dissipated in the dampers.

Never, ever ignore Newton. He must always be paid his dues as an answer.

How many Darwin Awards have been posthumously given because people slept during their physics classes?

  • $\begingroup$ Do I understand it correctly? You are saying the recoil would make the muzzle wobble around so much that it would hit him even if he is half a meter to the side of it? $\endgroup$ Jan 12, 2022 at 12:19
  • $\begingroup$ As in a armillary piece, the gun muzzle would first recoil backwards (hopefully straight backwards to maintain accuracy) by Newtons laws, and then the gun's spring-type dampening measure the muzzle has would rebound to its original position. However, lacking any atmosphere for friction, it would probably over-shoot the original position and extend forward. just as a spring will oscillate, until all of the energy is dissipated in heat and the muzzle stops moving forward and back. Like pushing down on the hood of a car, and the car oscillates back up and down, until the energy is dissipated. $\endgroup$ Jan 12, 2022 at 18:43
  • $\begingroup$ I am assuming the gun muzzle would have a lot of thickness, as it has to withstand a 220 ton shot., say two meters thick. If he were to stand in front of, but to the side of, the opening, he would still be standing in front of the front of the muzzle wall, but clear of the opening and the shot. The shot itself is 4 meters across so a two meter wall thickness is not unreasonable., and since he is not expecting a shock wave, he could easily assume standing in front of the muzzle but just to the side of the opening to clear the shot would be a macho thing., $\endgroup$ Jan 12, 2022 at 18:54
  • $\begingroup$ I could easily envision 'Joe Macho" actually leaning back against the front wall of the muzzle with arms crossed, waiting for the shot to pass him as it exits the muzzle. "Hey look at me, cool and casual Joe safe as a bug in a rug, because there is no pressure wave..." As an added bonus, the impact of the muzzle would probably launch him into space, right behind the shot. $\endgroup$ Jan 12, 2022 at 19:02

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