In Star Trek: The Motion Picture, Kirk says the following:

in order to intercept the Intruder at the earliest possible time, we must now risk engaging Warp drive while still within the solar system

My question, then, is what exactly is the risk of engaging Warp drive within a solar system?

  • 2
    This is kind of a weird situation, as in enterprise and TNG its totally acceptable to go to warp in the solar system.
    – user36770
    Jul 3, 2015 at 6:44
  • @AndrewKucenski exactly my thoughts! Jul 3, 2015 at 6:45
  • id assume the problems are that hitting the speed of of light in the solar system would allow you to hit a celestial body in the solar system fast and easily (like hitting Neptune within 1 second. ) but in reality those ships have such advanced computers that they would never "accidentally" run into anything in the sol system since its 100% mapped out.
    – user36770
    Jul 3, 2015 at 6:47
  • buy we see in both the reboot as well as first contact (plus some TNG) episodes that its in reality a non issue. however back in the 70s or 80s when the startrek motion picture was made they hadn't yet fully fleshed out the idea of warp speed.
    – user36770
    Jul 3, 2015 at 6:48
  • More to the point, how do they get anywhere at all? At full impulse it would take you sixteen hours just to get to Neptune. If you did the same arriving at AlphaCentauri that's almost two days of travel just to get to the nearest star. The writers just didn't think about this one too much...
    – J...
    Feb 3, 2022 at 21:14

1 Answer 1


This seems to be the subject of some debate, in-universe and out-of-universe.

From Ex Astris Scientia's article on warp propulsion:

Although it is definitely possible, there seem to be very different opinions whether it is advised to go to warp inside a solar system. In Star Trek: The Motion Picture, Kirk speaks of the risk of engaging the warp drive while still in the Sol system. Dax advises against going to warp inside the Bajoran system in DS9: "By Inferno's Light". In ENT: "Demons" T'Pol is worried ("Inside the system?") when Paxton orders the mining facility to go to warp. In TNG: "The Best of Both Worlds" we even see the Borg ship as well as the Enterprise-D slow down to impulse, although several seconds longer at warp speed may have saved precious time.

It has happened, however, on some notable occasions, without resistance to the idea and also without consequence:

  • Zefram Cochrane's first warp flight in Star Trek: First Contact takes place in the Sol system
  • Later warp tests in ENT: "First Flight" all occur very close to Earth too
  • The Enterprise NX-01 goes to warp within seconds after leaving the drydock in ENT: "Borderland"

One might counter that they probably didn't know any better, considering the technology was new. However:

  • Kirk's Enterprise goes to high warp in the Sol system in TOS: "Tomorrow is Yesterday"
  • In TOS: "Operation — Annihilate!", the Enterprise jumps to warp 8 within a solar system to pursue a Denevan ship
  • In TNG: "11001001", Picard's Enterprise goes to warp just after departing a starbase, which itself was orbiting a planet
  • In TNG: "Symbiosis", the Enterprise goes to warp within a solar system in order to rescue an Ornaran freighter
  • In TNG: "Descent II", Beverly Crusher orders the Enterprise to drop out of warp directly beside a planet
  • In DS9: "Past Prologue", two runabouts criss-cross the Bajoran system at warp speed

So what's the risk then?

Given that it is okay sometimes and ill-advised at other times, there must be specific reasons for why it is dangerous in some situations. The same Ex Astris Scientia article posits:

Gravity may obstruct warp propulsion in the vicinity of a planet, but most likely the much higher concentration of particles inside a solar system poses a problem. Modern starships have a deflector for that purpose. Cochrane may not yet have been aware of the danger, and he may have just been lucky that nothing collided with his ship. Still, it is possible that the Phoenix already had a navigational deflector. Even with a deflector, warp flight may be still a risk at high particle densities. In addition, it is possible that warp ships may endanger intra-system sublight traffic, so regulations may have been set up that generally disallow warp flight inside a (Federation) solar system.

  • 1
    it really seems to be writers discretion, especially since in journey home they literally are in warp through the entire solar system and slingshot around the sun to go back in time >.<
    – user36770
    Jul 3, 2015 at 6:51
  • OoU: Generally in most SF works, FTL is not possible near planets (mostly because of the gravitation). This is mainly to make some things not to easy and to avoid strategical nightmares like a war fleet, when ships in FTL are unstoppable and perhaps even undetectable, dropping out of FTL in earth orbit, start dropping anti matter bombs immediately ... To explain why the bad guys doesn't do this is very hard, until you come up with planetary shields and so on (what about poor/little/young colonies/outposts without?) With the limit the enemy can be intercepted far away from earth.
    – Hothie
    Jul 3, 2015 at 7:20
  • Of course (like many other things) in a big series like Star Trek this is not consistent and handled by the plot needs.
    – Hothie
    Jul 3, 2015 at 7:20
  • I remember that someone told me that going to warp near a planet could have devastating effects on the planet. I don't now where he gets this from, but this would make the warp drive an unstoppable weapon of mass destruction. So this narrative excusion does not work either.
    – Hothie
    Jul 3, 2015 at 7:22
  • "Operation: Annihilate!" Does NOT take place within our solar system: en.wikipedia.org/wiki/Operation:_Annihilate!
    – JRE
    Jul 3, 2015 at 8:14

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