Set in a distant future, reports of alien and drug traffickings have been on the rise and there was mounting pressure for Mr User6760, president of intergalactic interpol to resign. The traffickers made use of stolen tech to achieve fractional light speed travel and stealth to evade the space cop, now Mr User6760 must stop these traffickers or step down if there is still no result by the end of the term.

I am wondering what technology can be used by space cop to capture a suspicious spacecraft traveling at sub-luminal velocity without committing unlawful 2nd or perhaps even 3rd degree murder?

No FTL tech and arrest must be made before suspects exit heliosphere, the boundary between intergalactic free space and the jurisdiction aka furthest reach of the law. BTW we have identified that the stolen tech is actually antimatter propulsion engine so try not to sabotage it, we are space cop not space mafia!

  • 1
    $\begingroup$ Is the question related to what technology should Mr User6760, president of intergalactic interpol deploy to react in such situations (or in this very particular case). Or do you want to know how a 'cop on the beat' should react if s/he gets such an order from dispatch? Or what? $\endgroup$ Commented Mar 13, 2020 at 7:24
  • 3
    $\begingroup$ Well, if the Galactic Interpol is anything like the actual Interpol, then all they can do is send a Red Notice to the local police authority in the Solar System. (Interpol does not have the power to arrest anybody anywhere; it is an organization intended to facilitate co-operation between the various national police organizations.) $\endgroup$
    – AlexP
    Commented Mar 13, 2020 at 7:42
  • $\begingroup$ Could you tell us what you see as the difficulties? On Earth we have coast guards which have been doing this for centuries with nothing but fast boats and guns. What do you think would be different in space? $\endgroup$
    – David42
    Commented Mar 13, 2020 at 17:03
  • 1
    $\begingroup$ @David42: a car can pull over at the side of a road, a boat can capsize, a spacecraft can... explode is not an option! $\endgroup$
    – user6760
    Commented Mar 13, 2020 at 17:15
  • 1
    $\begingroup$ You could make 2nd and 3rd degree murder lawful after a "Stop or we kill you" warning $\endgroup$ Commented Mar 13, 2020 at 18:29

6 Answers 6


“Stop, or we’ll shoot!”

If they don’t stop, well, you shoot.

If you’re lucky you’ll be able to damage vulnerable bits like radiators or life support that would force the runaways to cut engines and wait for rescue. If you’re really lucky you have some kind of remote cutout for their engines and can just use that.

Otherwise your only real option is to get into such ranges that you can kill the ship with your weapons and order them to cut engines and prepare for boarding. Use a missile so you can self destruct it if they lose their nerve before it’s too late.

(If you can’t get into kill range with any weapon, you can’t really catch your fugitives anyway)

The antimatter engine isn't really a major consideration if the fugitives are trying to run away - space is really darn big and even the engine were capable of detonating 20 kilos of antimatter all at once it wouldn't do much of anything as soon as they get about as far away as the moon (if that)

  • 1
    $\begingroup$ Stop, or we’ll shoot! "Well, fuck off, pig. I just rigged the antimatter engine that we... ummm... borrowed to explode if you try something. In case you dropped off from college, let me tell you what the explosion of 20kg of antimatter will do to the Solar system. I suggest you go ask Mr User6760, president of intergalactic interpol, before you do the last thing of your life" $\endgroup$ Commented Mar 13, 2020 at 7:27
  • 10
    $\begingroup$ 20 kg antimatter (if fully annihilated with the same amount of matter, which will not happen) is still just 860 MT TNT-equivalent. You do not want it on or near a planet, but in deep interplanetary space it is harmless. The sun produces bilion times that energy in every second $\endgroup$
    – b.Lorenz
    Commented Mar 13, 2020 at 8:39
  • 1
    $\begingroup$ Pretty much. Even a naive sphere area based calculation drops all that energy to peanuts very very fast. You may as well throw said peanuts at the cops - at least you'll survive it and they might have an allergy $\endgroup$
    – Pingcode
    Commented Mar 13, 2020 at 9:14
  • 1
    $\begingroup$ @b.Lorenz hell, if they have a way of converting radiation to energy, they can put out some collectors and get a free recharge out of the deal too $\endgroup$
    – Bitsplease
    Commented Mar 13, 2020 at 15:50

Tugboat drones

drones, unencumbered by squishy meat bags, can accelerate much harder than your bad guys can. Once they catch up the drones could try to disable engines (but that’s complicated and might cause explosions) or they could batten themselves onto the hull in great numbers and use their (vastly more powerful because there’s no need for life support to take up space) engines to oppose the motion of the bad guys ship.

Even if they can’t flat-out stop the enemy they can try to turn them (I assume your drones will be more powerful than the RCS thrusters on the target) so their main thruster is useless for acceleration. Then it’s a simple matter of the drones dragging your bad guys home, safe and sound.

And if needs be you can always just use them as missiles and blow the bad guys up, Dirty Harry style.


There ain't no stealth in space

Added to the general rules around "Hot pursuit" mean that once you have your target located, and you're in pursuit, the jurisdictional boundary no longer applies.

If the enemy has an impenetrable fortress, make sure he stays there - General Callus Tacticus

Of course you could just knock out their engines and walk away. A criminal that you know the exact location of might as well be in custody for all practical purposes, except you don't have to feed them. He's in his ship, travelling at speed $v$ on bearing $xyz$ at time $t$ and you know where he is for the foreseeable future with all the evidence on board. No engines means he can't change course and can't slow down. Monitor and collect at your leisure for court dates.


Speed is relative.

spacecraft capture https://exploderblog.com/index.php/2019/02/11/recap-you-only-live-twice/

The problem is not that bad guy is so fast. It is that you are so slow!

  1. Borrow similar tech.

  2. Fit out your ship the Giant Clam with tech.

  3. Catch up to bad guy. Now bad guy is not so fast. And there is nothing around for either of you to bump into.

  4. Giant Clam does what Giant Clam does best.

  5. Robot gorilla space marines enter bad guy ship, remove bad guys, turn them loose in Clown Car space ship.

  6. Bad guys in Clown Car captured on video for other bad guys to laugh at.


what technology can be used by space cop to capture a suspicious spacecraft traveling at sub-luminal velocity without committing unlawful 2nd or perhaps even 3rd degree murder?

If a cop follows the procedures in the exercise of his duty, he cannot be charged with murder.

And I hope you are aware that without the threat of recurring to potentially deadly force you won't be able to stop anybody, not even granny while crossing outside the zebra path.

You have rules of engagement dictated by your superior, follow them.

Most likely you will be required to, in order:

  1. identify yourself as a police officer
  2. demand the suspects to halt
  3. once the suspects do not respond, issue another warning with threat of recurring to forced stop
  4. once they again do not respond, go with force.

Force can mean:

  • put obstacles on their path. Like earthling cops put spikes and nails on the road to stop cars, just put scraps on their trajectory. At the speed they are going they will be forced to stop/detour
  • active fire: lasers, rockets, whatever you have in your arsenal
  • do you have a tractor beam? use it to pull them back

If they happen to find death in the proceeding, you have followed your rule book, you are good and covered.

  • $\begingroup$ Let me introduce myself again, I'm Mr User6760, president of intergalactic interpol. Do you really suggest that I have to take the "if you want to do something right, you have to do it yourself" course of action? $\endgroup$ Commented Mar 13, 2020 at 7:19

The problem with flying criminals is even worse than with driving criminals. They can literally go in any direction, so unless you can surround them well and truly (something nearly impossible at those speeds) just chasing them isn't going to do much.

Your best bet in this scenario? Get them before they set off. Track them to wherever they undertake their illicit activities, and bust the whole operation at once.

If getting them in transit is your only choice, your success will depend on one thing only. What tech do you have available? If you have tractor beams or EMP then it's a done deal really, but if all your weapons are destructive it gets more complicated.

The only way to arrest someone who literally can go anywhere, is to make them believe that surrender is their best option. Either threaten them with superior weaponry to get them to stop, but historically that hasn't always worked out for the best. You could do the mafia option and threaten their friends or family (if known), but this might not get you reelected.

If you have very precise weaponry, you might be able to damage their spaceship minimally, but just enough to render it inoperable. I would start with the life support systems rather than propulsion. They will have the choice of surrender or suffocate, and human nature will not really choose suffocation. If it is alien nature though, that's anyone's guess...

  • 1
    $\begingroup$ Nitpick, EMP won't work they will still be travelling the same speed just unable to control anything. $\endgroup$
    – IT Alex
    Commented Mar 13, 2020 at 17:25
  • $\begingroup$ There is no hiding in space. Once you know where the fugitive is, you can track him with a telescope and he won't be able to run in an unknown direction. Except by moving behind a planet and expending a huge amount of energy to change course (the planet can assist but not much if you start the maneuver that near). Interpol has multiple telescopes, so hiding behind a planet is difficult - landing on it is a better idea, there you can hide. $\endgroup$
    – toolforger
    Commented Mar 14, 2020 at 7:13

You must log in to answer this question.

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