As XKCD recently educated some of us in a "What If" blog post, playing (near) light-speed baseball on a planet with an atmosphere is generally a bad idea.

The TL;DR version translates to: A baseball moving at 0.9c is traveling too fast for particles in the atmosphere to get out of the way. The resulting atomic collisions set off a chain reaction that feeds off of the rest of the surrounding atmosphere, turning into a massive nuclear explosion. This does not bode well for the batter, the pitcher, the catcher, or anyone else within a few miles of the reaction's epicenter.

Bringing this issue into context with the Star Trek universe, there was a point in the 2009 movie where the Enterprise came out of warp amidst the clouds of Saturn's sixth moon, Titan. Presumably, this means that the Enterprise at some point was traveling through Titan's atmosphere near or above the speed of light.

Is there some principle of warp drive technology that allows the Enterprise to avoid the fate of the baseball in this situation, or should that interaction have actually destroyed (at least) a good part of the Enterprise and Titan?

  • That was Titan? I always assumed it was meant to be Saturn's rings... May 12, 2013 at 20:33
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    In The Voyage Home, the Klingon ship jumps to warp while still inside the atmosphere, and no-one on board who would know, Kirk, Spock, Scotty shows any sign of worrying that doing so would damage either the engines or the planet. The accepted answer is therefore wrong, canon trumps all.
    – Gaius
    Jan 27, 2015 at 12:25
  • As Thaddeus deleted my critical comments on his accepted answer, I'll put the criticisms here. Thaddeus doesn't seem to understand that on this site, canon information trumps real-world science--although traveling at relativistic speed or using an Alcubierre drive in an atmosphere would cause a tremendous explosion according to actual physics, the evidence from "The Voyage Home" shows that Trek warp doesn't have the same problem, and Thaddeus also provided no canon evidence for the claim that warping out of nebulas was dangerous or would strain the deflectors.
    – Hypnosifl
    Jan 13, 2016 at 22:21

3 Answers 3


Using previous behaviors as a reference, warp drive is not done near the atmospheres of planets except under extreme duress, both due to the density of particulate matter (the atmosphere itself) and the gravity well of the planet disrupting a stable warp field.

Under Impulse Propulsion

  • We have seen starships, using their deflector array block atmosphere-like particles since they go into planetary nebula

    • to escape enemy ships, investigating phenomena, roaming the Badlands, for example
    • We also know they can go to warp in those areas (but prefer to only under duress due to the strain on their deflector array).
    • They can move at speeds up to half impulse (150,000 kps) through such phenomena, the denser the nebula, the lower the top speed.
  • If a ship needed to approach a planetary atmosphere under impulse power, in normal space their deflector array and their shields would be up to prevent damage caused from moving that quickly into a planetary atmosphere.

  • This would be unsustainable as the atmosphere would soon tear the ship apart even with this arrangement.
  • Most starships were not designed for atmospheric descent, let alone at hundreds of thousands of miles per hour.

  • It is unknown how Star Trek era technology handles the idea of infinite mass as they approach the speed of light, but if that concept holds steady, no ship ever approaches a planetary surface at light speed because of the environmental destruction possible as an intense and localized gravity field interacts with the planetary one.

Using Warp Drive

No ship would try to go to warp inside of a planetary atmosphere for the same reason, the forces required to keep the atmosphere from tearing the ship apart would be easily as great and applied instantly. - It has never been made truly clear if the ship is still completely within our universe (i.e. subspace) but using the fact starships rarely go to warp in nebulas, would lead me to believe they are still affected by things in OUR universe even while they are in subspace.

Could a ship do it anyway, overriding safety protocols?

  • Yes. If a ship were in the exosphere of a planet (where the atmosphere is thinnest and basically resembles space) it could be possible and still dangerous to go to warp. Since they would be leaving the atmosphere they would have less strain on the deflector array not more.

  • Since we don't see ships plunging into atmospheres and going to warp as a combat tactic, we can assume it is more destructive to the ship than to the planet and not considered a viable means of attack. Atmospheric friction incinerating the ship after overcoming the shields in a matter of milliseconds.

  • Dropping INTO a planetary atmosphere from warp would mean the ship would need to be at a complete stop when it came out of warp in the thinnest atmosphere possible and would then need to allow normal gravity and maneuvering thrusters to come online to control the descent.

  • Shockwaves and atmospheric disturbances from their arrival in the atmosphere would be generated and could possibly have long-term effects on weather patterns as the energy of their arrival would be dispersed into the planetary weather system.

The consequences of such a maneuver around an inhabited world could be a catastrophe and no responsible (or sane) starship captain would consider this except in an emergency.

As an interesting aside, the theory which mostly resembles warp drive known as the Alcubierre Drive is postulated to, if a ship were to be able to use it, affect matter in space when the ship activated its drive. This matter once trapped within the warp field would be bound to the ship and gain potential energy as the ship travelled. As the ship exited warp space matter that moved along with the ship, would release its energy as radiation in the form of gamma and other high energy particles. The potential of such an event could possible bath the planet in deadly radiation.

The problem is that the Alcubierre Drive spaceship is going to encounter matter during its trip: space is only nearly empty, not completely empty. Matter traveling towards the ship, the paper says, will become “time locked” with the ship. When the ship decelerates, these hitch-hikers are released from the bubble emitting huge amounts of energy as gamma rays and high-energy particles. Warp drives are planet killers, Sydney University students find. --The Register

  • +1 I remember from the Star Trek Encyclopedia that Full Impulse speed was 1/4 light-speed, but this has been known to vary. Voyager had it at 0.8c. In any case, it's not fast enough to start worrying about infinite mass. There is, to my knowledge, nothing in the Star Trek universe for near-light speed beyond those ranges that isn't warp speed, the lowest being Warp 1 or c, and done in subspace, where relativist physics don't apply the same.
    – MPelletier
    Jul 17, 2012 at 22:14

Warp drives in Star Trek are a fictional version of the real-world physics concept of the Alcubierre drive. From the Wikipedia article:

...Alcubierre proposed a way of changing the geometry of space by creating a wave which would cause the fabric of space ahead of a spacecraft to contract and the space behind it to expand. The ship would then ride this wave inside a region of flat space known as a warp bubble, and would not move within this bubble, but instead be carried along as the region itself moves as a consequence of the actions of the drive.

The energy costs of such a drive are difficult if not impossible to achieve, and even if those were overcome, implementing an Alcubierre drive might result in a very different setup than what one sees in Star Trek. However, both this article and the Memory Alpha articles on warp drive do not address whether or not a starship traveling at Warp Drive would intersect matter in normal space, such as an atmosphere. Given the sprawling nature of Star Trek canon, if such an explanation exists, it's possible that there's another one that contradicts it!

However, there is one clue that may help us here: Starships in the Star Trek universe are all equipped with a navigational deflector:

The navigational deflector... is used to deflect space debris, asteroids, microscopic particles and other objects that might collide with the ship. At warp speed the deflector is virtually indispensable for most starships as even the most minute particle can cause serious damage to a ship when it is traveling at superluminal velocities.

A starship is riding inside a warp bubble, which is possibly outside of normal space (although I can't confirm or deny this). Either way, it's fairly clear that they can see and interact with the universe outside of their warp bubble.

Since a deflector dish is a fairly prominent part of a starship, one can make the reasoned assumption that these dishes and their subsystems would have to be fairly powerful to reach across vast distances as well as quick, to react to pieces of matter approaching the ship at warp speeds. (On the other hand, smaller warp-capable ships, such as shuttlecraft, often have no visible navigational deflector, so perhaps these systems get exponentially larger as ship size increases.)

Going back to your original question about the Enterprise coming out of warp in Titan's atmosphere, it's safe to say that the ship's navigational deflector took care of pushing the atmosphere out of the ship's way. However, these systems are designed to handle space dust and small asteroids while traveling in (mostly) empty space, so a planetary atmosphere would probably put a big strain on the system, and might even be dangerous to the ship.

In conclusion, I'd guess that a starship could enter or exit warp in an atmosphere, but would probably prefer to not put such a large strain on it's navigational deflector except in emergency situations.

  • Having not read the wiki articles, and going off my purely uninformed intuition of how warp drives work in Star Trek, the warp bubble is either 1) a perturbation of normal space time (i.e. a localized disturbance but otherwise normal space time) or 2) a bubble of space time that intersects with normal space time (i.e. not parallel), but is not orthogonal to normal space time (i.e. interacts with normal space time). These 2 concepts are essentially the same from an onlooker's perspective.
    – MBraedley
    Jul 17, 2012 at 10:49
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    They aren't the Alcubierre drive, because that theory was only formulated in the last 20 years, and Star Trek pre-dates it by another 30 years. While the two concepts are similar, Star Trek can't be based off of it.
    – John O
    Jul 17, 2012 at 13:56
  • @JohnO - But they fit the concept of the Alcubierre drive very well. All the stuff about warp bubbles was introduced in the later Star Trek series. It matters not at all that the concept was formulated after the original series aired. Edited my answer to help clarify. (However, the real-world answer is that Star Trek's warp drive is a fictional concept to enable stories, and its properties are a matter of fitting whatever the plot requires.) Jul 17, 2012 at 14:43
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    The original series would have described it as a field, if they ever did (I can't remember hearing it in an episode). The "bubble" thing is definitely an invention of TNG, and probably influenced Alcubierre's choice of words a bit. And not to be pedantic, but the energy cost of such a thing is actually "enormously low" as I understand it. You need negative energy for it to work, something no one is even certain exists.
    – John O
    Jul 17, 2012 at 14:47
  • I read about negative energy in the Wikipedia article, but I don't understand that part. I did follow the part where you may need an Alcubierre drive to set up markers to actually use an Alcubierre drive! Jul 17, 2012 at 16:29

It must be fairly okay to do so, because… they have.

Sulu takes Bird-of-Prey to warp in atmosphere

Granted one little scene in a movie isn't typically enough to write the whole process off as entirely safe… however.

The practice of associating Star Trek's warp drive with Alcubierre is at once easy and incorrect. Apart from the implicit "science is magic" effect of faster-than-light travel anyway, Alcubierre's theory didn't exist to influence the creation of warp drive, so while it's fun to associate it to warp drive it isn't really useful for these 'what-if' situations.

Given what we do know about the average space-worthy ship in Star Trek - they're capable of FTL via warp drive and they use deflector technology to 'clear the path' in front of them - it's feasible that even if the 'planet killer' aspects of Alcubierre's theory play into ST warp drive, the deflector politely scoots particles out of the way.

That's a guess of course, but then again, Kirk didn't accidentally the whole Sun by dragging the Earth's atmosphere with it during a slingshot maneuver, so.

  • The Klingon ship Hegh'ta went to warp near a sun which caused a solar flare than destroyed enemy ships in TNG: Redemption (Part 2). Aug 10, 2014 at 14:36
  • Stars != planets. I'd be willing to buy the idea that a warp field has a different effect on two different things. The stolen BoP in ST IV is in the high atmosphere when it engages the warp drive, whereas Kurn's ship is depicted as being dangerously close to the surface of the star. The surface of a star being plasma, and plasma being constantly referenced as A Thing on Star Trek (the M/AM engines create drive plasma/warp plasma/whatever, so warp drive and plasma are tied together), there's some kind of "dot dot dot" connection between them.
    – Stick
    Aug 11, 2014 at 21:39
  • Maybe a more interesting question would be, what happens if a ship goes to warp in the center of a populated area? What happens if the HMS Bounty jumps to Warp 4 while parked outside 10 Downing Street? Probably bad things...
    – Stick
    Aug 11, 2014 at 21:41
  • Yes, stars are not planets. I was referring to being in the atmosphere. Both plasma and gas are both fluids. (Plasma is gas that has become ionized in a certain way. It is sometimes called the fourth state of matter. en.wikipedia.org/wiki/Plasma_(physics) .) Something moving through either of them would have an effect. The Bounty (the stolen BoP) would definitely cause some sort of disturbance in the atmosphere. As for the exact nature of that disturbance, who knows. Jan 27, 2015 at 4:51
  • It is also possible that a warp field/subspace field might have an effect on a planet or star's magnetic field. I do agree that being close to the planet's surface would definitely have some effect on a liquid (such as being over the ocean and causing an eruption of water) and probably have some effect on a solid (throwing dirt/rocks/cars in the air) Jan 27, 2015 at 4:51

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