• Show Spoilers
• Night Vision

# Space Friction aka: Friction In Space

"So you can just slow down and make a sharp left in space?"

Isaac Newton turned the world of physics upside down when he observed his first law of motion:

A body in motion will tend to stay in motion, in the same direction and at a constant speed, unless acted upon by an outside force.

This was earth-shattering stuff when he introduced the notion — in 1687! Sadly, most writers for science fiction TV shows and films are apparently still stuck in Aristotelian physics — according to which a body in motion will always slow down even in vacuum — and just don't get a single clue of how proper Newtonian physics work.

Basically, goes the misconception, if your engine breaks down in space, your ship will quickly slow to a complete stop. Writers do this because if the engine in your car breaks down, you come to a stop, and if the engine in your boat breaks down, you drift at a random low speed at the whims of the currents. Based on these experiences, it feels intuitive to write that spaceships will act this way.

However, the reason these things happen is friction. On a straight road, with good tires, you can coast quite a long way on even a slight downgrade. In space, where there is no friction between the car and air to contend with, you can coast even at top speed almost forever (albeit perhaps not in a perfectly straight line, due to gravitation), or until you hit something, which, given how big space is, is literally astronomically unlikely.

For that matter, the entire notion of only having enough fuel to travel so far is a little suspect: if you've got enough fuel to reach top speed, you've got enough fuel to go anywhere; once you reach top speed, you can just shut the engine off and coast, though this is assuming you're flying along a ballistic trajectory. Of course, it would become a problem if you don't have enough fuel to stop at the end — or if, for whatever reason, you have to turn somewhere, or if your engine fuel doubles as power generator fuel, which would cause a black-out in your ship (which, if it comes up in a Space Friction plot, generally means the crew has a few hours to restore power before running out of air). Even so, this would result in a broken-engined ship perhaps missing its target or crashing into another, not stopping dead.

Exotic propulsion systems of the sort needed to exceed the speed of light are exempt from the normal laws of physics and can reasonably be presumed to expend energy even at a constant speed, just holding the laws of physics in check, but it's curious that the effects of such drives always cause space to behave exactly like an ocean—a ship said to be "adrift" will be moving at a random (low) speed and direction or practically not moving at all.

A form of Hollywood Science. See also Space Is Air, Space Is Cold. Related to Friction Burn. Contrast Frictionless Reentry.

## Examples:

open/close all folders

Films — Animated
• Transformers: The Movie had a variation of this; Astrotrain, in space shuttle mode, pleads to his passengers to "jettison some weight, or we'll never make it to Cybertron". This seems to be an excuse to throw the other, dying Decepticons out of Astrotrain, but note that his engines were still on and burning brightly for some reason. Parodied here.

Films — Live-Action
• The dogfights in the Star Wars film series were intentionally choreographed around old World War II dogfight footage, and thus visibly obeying this trope. The most noticeable application of Space Friction however occurs whenever a ship explodes in mid-flight: its explosion will be motionless despite whatever inertia the ship had previously. One instance where this can be seen very clearly is when the Y-Wings are making their trench run in close formation in A New Hope. One of the Y-Wings explodes, and the other Y-Wing suddenly leaps forward, leaving that explosion behind him.
• In Spaceballs, a spaceship brakes... and even emits a kind of shower of sparks, like a car would with burnt rubber.
• Well, one of the spaceships looks like an RV. And let's not even talk about what the other spaceship looks like...
• Lone Star's Space Winnebago actually leaves burnt rubber tracks while doing a U-turn. In space. Lampshaded by Lone Star: "Hang on, Barfo, we're gonna make space tracks."
• The Spaceball One, however, "brakes for nobody."
• In Star Trek III: The Search for Spock: the Excelsior is accelerating up to transwarp when Scotty's sabotage kicks in, everything breaks down and it coasts to a stop, accompanied by a humorous "engine sputtering to a stop" noise.
• It may be a subversion, as Excelsior is in Earth's orbit. Her engines are no longer providing the thrust needed to achieve escape velocity, so she is losing momentum due to Earth's gravity. Although that would open up a whole new can of worms in Gravity Sucks, as an orbiting object by definition can't be decelerated by gravity.
• In Star Trek IV: The Voyage Home, a ship whose power is zapped by a probe is actually seen to coast to a stop, while the Miranda class ship seems to continue on its direction — however while turning at a weird angle to indicate it's out of control.
• In Star Trek: Nemesis, After Captain Picard rams the Scimitar causing much of Enterprise's hull to penetrate that of the other vessel, Shinzon reverses his engines to separate the two ships. It works quite nicely, and all without any opposing thrust from Enterprise.
• Actually, it would work nicely, as the structures of the two ships aren't very well bound together. They have simply been pushed nose to nose, the inertia of the Enterprise, along with the weak coupling strength of the materials would mean that this maneuver would be perfectly workable. It even makes one thing make sense: If a ship has the engines and thrusters to perform the moves we see the Nemesis do, then it should be able to back up incredibly quickly. We also see it do this: the emergency stop. So why, when it is thrusting away from the Enterprise, does it move so slowly? Answer: they were both accelerating due to the thrust.
• Played straight in Mission to Mars, most notably where a character with a rocket pack tries to rescue another character who had done something silly — complete with fuel gauge running down. Kind of sad, as they'd done the space flight physics pretty well up to this point. Also, the friction from the space air doesn't seem to be affecting Woody — oh but that must be because he's not wearing his rocket pack any more ...
• The space friction in Starcrash is so great that it leaves a trail by which you can track a spaceship.

Literature
• Is a major driver in the plot of Poul Anderson's novel Tau Zero, where the Bussard-ramjet ship Leonora Christie suffers a failure of part of its engine. You see, Bussard-ramjet ships can accelerate near the speed of light using magnetic fields to fuse interstellar hydrogen to drive the ship; the reaction is self-sustaining once started. Problem is, as the ship accelerates relative to the rest of the universe, so does the oncoming hydrogen in the ship's path, which would result in the instant destruction of the ship if the fields fail. The ship has a special decelerator module on its engine for slowing down safely. Guess which portion of the ship's engine fails... resulting in the ship's crew having to keep on running until they find space empty enough to allow the engine to be shut down and repaired. There are a couple of false starts, as by the time they hit intergalactic space they're going so fast that even the incredibly thin intergalactic matter is still just too dense, and so on... and meanwhile time is dilating more and more. They then have the problem of finding a new home, as humanity is now long dead due to the eons that have passed outside the ship — and indeed the universe itself is running down. Their solution is... creative. Unlike most that use this trope, this is based on real science.
• Only according to our understanding of Bussard Ramjets at the time. Since then, we have made the discovery that a ramjets maximum velocity relative to the medium it is moving through is exactly the same as its maximum exhaust velocity, so endless acceleration is not quite realistic.
• In Stanisław Lem's The Invincible, the eponymous ship goes in continuous acceleration mode for several months by firing its main engine, and then needs only a few hours of deceleration using less powerful retro-engines.
• Justified in the Lensman stories: the key to interstellar flight is a device that cancels a spaceship's inertial mass, so top speed is determined by the point at which a spaceship's thrust is exactly counterbalanced by the friction of the interstellar medium. With sufficiently powerful Impeller engines, this counterbalance speed can be many times the speed of light. Since a spaceship doesn't have inertia, turning off the engines causes it to come to an instant stop. E. E. “Doc” Smith can't seem to decide if a spaceship is completely dead in space without its Bergenholm (the magic get-rid-of-inertia gadget) or if it still has its original speed achieved before starting the "Berg". However, with the speeds you can get with a Bergenholm, any possible "inert" speed is full stop by comparison.
• In all the Lensman books he made it clear that when you turned off the Bergenholm you instantly reverted to the exact same speed and direction you were going in when you turned it on. What he didn't make clear was what that speed and direction actually was. When you are sitting still on the surface of the earth you are actually going east at up to about 1000 MPH due to the Earth's rotation, about 18 miles per second because of the Earth's revolution around the Sun, add to that the Sun's movement around the Milky Way, etc, etc. Turning off the Impeller engines, while the Bergenholm is still engaged, causes the ship to come to a complete stop instantly (the moment they bang into that first hydrogen atom in the interstellar medium). Turning off the Bergenholm itself causes the ship to resume its "intrinsic velocity", i.e. the sublight velocity it had before the Bergenholm was engaged.
• In Alistair Reynold's Revelation Space a character wonders why an interstellar light-hugger ship is aerodynamically shaped given that space is a vacuum. She is told that at 0.999c the interstellar medium is dense enough to almost function as an atmosphere as far as friction goes.
• Inverted in Edward Llewellyn's Salvage and Destroy (1984). The Transplanted Humans scouting out their ancestors' homeworld are briefly flummoxed by the spaceships depicted on TV.
"It suggests a ship designed by an engineer who knows a bit about interstellar space, but not much. He thinks space is a vacuum so he's let everything stick out. At the speeds she'll have to move under drive to get anywhere half those stick-outs'll be burned off by plasma friction ..."
And then they see examples of spaceships with wings.

Live Action TV
• One episode of Space: 1999 even showed one of the Eagle ships rocking in space.
• Star Trek, unsurprisingly. In fact, in an instance where someone takes advantage of inertia (Star Trek: The Next Generation: "The Battle") by letting a derelict coast alongside them, everyone else is amazed by the notion — and, indeed, it turns out that his decision was prompted by his being Not Himself. In the other known instance ("Booby Trap"), it takes Geordi being inspired by ancient records to come up with the idea of escaping an engine-detecting minefield by pulsing the engines once and then coasting.
• Though at least on Next Generation they have separate responses to the captain when the controls read all stop and when the sensors confirm all stop, implying that the all stop command requires the vessel to actively slow down.
• This was in the first episode, and it's an aversion of the trope. After they set the controls to all stop, you could actually hear the engines increase in power (they were at sublight, so impulse engines) as they slowed down, until they said "now showing all stop" and you heard the engines stop.
• It's also averted in some episodes — Final Mission springs to mind, along with Soldiers Of The Empire.
• Farscape could usually Hand Wave this one, since Moya was a living entity, it was assumed her method of movement was energy-based... somehow. But it's specifically brought up when Scorpius' neural clone takes over Crichton's mind with Aeryn in pursuit. He taunts her that while he has been trained to fly jets in a planet's atmosphere and gravity, Aeryn has not.
• That's actually a potential aversion. Crichton presumably learned to fly in familiar Air Force fighter jets. Space combat would be extremely different to jet combat, regardless of what Star Wars shows us — consider the Starfuries on Babylon 5 and the way they coast, reverse, spin on their axes, and move nothing like any aircraft on Earth. Just because Aeryn's ship can fly in an atmosphere doesn't mean she's going to be any good at it. When you have the capacity to raze entire cities to the ground from high orbit, atmospheric dogfighting probably isn't high on your list of training priorities, and her atmospheric flying experience most likely consists of ship-to-surface and back again.
• Battlestar Galactica & Buck Rogers in the 25th Century were terrible for this. The "fighters" always had to have engines on and had to boost thrust to do anything worthwhile. The best stupid move was Buck's "brilliant" fighter jock tactic: barrel rolling around an axis, without ever changing direction. Somehow, this managed to throw off opponents. (Probably they were laughing too hard.)
• The reimagined Battlestar Galactica corrected this; the fighters could turn 180 degrees on axis to face backwards while maintaining the same direction and speed, fire maneuvering thrusters to change direction, and coast with engines off.
• In the Doctor Who episode "The Beast Below", the Doctor can tell something strange is going on because Starship UK is moving through space despite the engines not running. Which is obviously impossible.
• Firefly: "Out of Gas" has the ship come to an apparent "stop" when it runs out of fuel, which is actually the result of the setting's curious interplanetary drive system losing power. note
• Red Dwarf did this in "Demons and Angels" when the Dwarf temporarily explodes and the crew narrowly escape in a Starbug. The nearest asteroid with an "S3"note  atmosphere is six hours away, but they only have enough fuel for five hours' flight. That's not the last bit of fridge logic in this scene. Red Dwarf also ditched Space Friction in a later episode (see below).

Tabletop Games
• In Battlestations by Gorilla Games, standard missions take place in deep space between rival vessels. At the beginning of every turn there is an "upkeep" phase where all your functioning engines produce power, ships' systems drain power, and you lose a point of velocity.
• Justified in Spelljammer. Apart from working with magic, the Space Ships have an emergency brake in the form of an array of rods that, once activated, are 'immovable' (they suddenly acquire tremendous inertia and thus act as very powerful anchors, decelerating the ship: notably, they're not truly immovable, since objects of infinite inertia would cause the ship to tear itself apart around them in an effort to reach zero speed instantaneously.)

Video Games
• Justified in the Home World series—according to the Historical and Technical Briefing, the Hiigarans' (and presumably other races') ships are designed with micro-thrusters that provide force opposed to the direction of the engines' thrust, thereby simulating drag. This was done partly for safety reasons, but mostly to keep the pilots from going crazy trying to figure out how to maneuver in a vacuum.
• In the MMORPG EVE Online, this is taken to ridiculous extremes for an otherwise acceptably scientific game. Not only does space have friction in EVE, but avid fans have actually done the math and determined that space in the EVE universe has the consistency of WD-40. When paired with the fact that a ship traveling on traditional propulsion methods actually has a top speed and an acceleration curve, it strains Suspension of Disbelief.
• It's stated somewhere amongst the backstory that warp drives drag against the fabric of space, so a ship without a warp drive would be able to go as fast as its shields could handle (dust gets dangerous at high speeds), although it would be limited to slower-than-light travel.
• The Apocrypha expansion of March 2009 removed a feature that caused one's ship to shake violently when entering or exiting warp, as if it were flying through an atmosphere. People complained, and it was returned in a subsequent patch.
• Explosion shockwaves in space. Possible for faster ships to escape kinetic explosions among other things.
• The FreeSpace video game series.
• It's just not fun trying to chase after a ship that suddenly became disabled when it was on its afterburner. Besides, you've got to worry about that invisible barrier 150km away from your starting position that causes you to "collide with yourself" and blow up.
• The FSOpen project actually implemented real-world physics at one point: more as a proof-of-concept thing than anything else. After all, the engine was designed around Old School Dogfighting, so playing with "Newtonian physics" completely broke the AI and all game balance. A few mods for the game engine have since used the altered physics, with custom AI written to handle realistic physics.
• In the Xbox 360 game Project Sylpheed, your ship steers as if there's air resistance in space, with this becoming more pronounced in atmosphere. In a related note of bizarreness, cutting the engines and coasting works even in atmosphere, despite the fact that the ship should fall out of the sky if it's not done in an effectively zero-G environment.
• In Star Control II, Hyperspace has friction, resulting in a continuous need for fuel, and the ship slows to a stop when fuel runs out. However, space travel in solar systems and in battles obeys Newtonian physics, and fuel expenditure only occurs when using the engines to alter course. However, each ship still has a set maximum velocity, which only can be surpassed by slingshotting around a planet. Even then, if you apply additional thrust, it actually slows you down until you reach your "max speed" again. Yet the Arilou Lalee'lay, hinted to have perpetrated the various alien abductions and flying saucer appearances on Earth, fly saucer-shaped ships that stop and start instantly with no inertia, as often seen in depictions of flying saucers.
• The Arwings in the Star Fox games have their engines firing constantly, bank into turns, and even open their wings for an "air brake"... in space. Now, this behavior is perfectly normal when the crew is on a planet, but in space, the Arwings would be accelerating constantly in one direction.
• Shown in GuavaMoment's Let's Play X-Com: Apocalypse as a sign of Tynam's growing insanity and the excessive levels of bad research present in X-COM: Interceptor.
• In the game Battlecruiser 3000 AD (possibly also the prequels and sequels in the same series). When you stop applying thrust you will eventually stop. But if you shut down all power to the engine you will go on with constant speed until you turn.
• Ordinary functional ships in Escape Velocity limits this trope (there is a top speed, but the only circumstance in which such ships slow down on their own is if they had topped that speed with afterburners). Disabled ships, however, slow to a halt (presumably to make it easier to dock with them), and ships with inertial dampeners only move while engines are running.
• This happens in the "planet-less" levels of Angry Birds Space, making things difficult because any objects you collide with that should just continue to collide with other objects or otherwise keep floating until they leave the screen, will instead gradually slow and stop.
• Fans of the X-Universe series guesstimate that the universe has the viscosity of maple syrup. Many sectors also have the visibility of maple syrup. However, X Rebirth explains that the space friction is due to the ship's automated flight assists. Update 3.60 allows players to disable the flight assist, allowing the Albion Skunk to freely spin about with no friction.
• In Project Space Station, your orbital construction equipment has a top speed, and coasts to a stop when you stop firing the engines. Since the game also tracks your available maneuvering fuel, it's clear that this doesn't come from the control computer firing the jets on your behalf.
• Played painfully straight in the classic Atari 8-bit game Star Raiders. Not only is sublight travel performed by setting your spaceship's engines to fire continuously (consuming energy in the process), but if they get damaged your ship abruptly comes to a halt, leaving you to sputter to the nearest starbase for repairs.
• In the arcade classic Asteroids, you can drift for about 2-3 screen's worth before coming to a stop, depending what speed you're going. The arrow buttons work like thrusters, requiring reverse thrust to slow down.
• Freelancer tries to play this both ways. While ships do slow down when you reduce their thrust, the instance of a "Kill Engine" button which allows the player to make use of Newtonian physics (complete with realistic acceleration if the player uses the afterburner) suggests that the aerial-style movement is a product of the designs of the ships.
• This was previously done in Tachyon: The Fringe. Ships have a top speed, but with the clever use of afterburners and inertia, the ship's speed can nearly double. Of course, as soon as you reactivate the engines, your speed goes back to top speed. Not to mention all the banking and barrel-rolls.
• Averted in this Freelancer mod, a Halo-universe-based mod which adapts the Freelancer system to instead use Newtonian physics.
• Actually there is a slight amount of friction, and your velocity slowly drops. However in the scale of the game it is not easily noticable, unless you're in a nebula.
• From the Depths has air resistance in high-orbit. While it is noticeably lower than air resistance when at altitudes where air-breathing jet engines work, one must still keep their spacecraft streamlined to maximize their velocity. Of note is that spacecraft will never outrun an airplane courtesy of jet engines being significantly more powerful than the ion engines that spacecraft must use.
• Comet Busters! inherits this from Asteroids, and goes one further by letting the "Disruptor" special ability act as a brake. The manual handwaves all this as an effect of "solar winds".

Web Comics

Western Animation
• Applied crazily in Futurama, in the episode "Godfellas": when Bender is launched out of a torpedo tube, he keeps going. He's realistically able to slow himself a bit by throwing away pieces of treasure he had stored in his compartment, but runs out of objects to throw before he's stopped himself completely. However, the ship cannot catch up to him because it was moving at "top speed" when they launched him, so he was moving even faster.
• Another episode stated that the ship went 99% of the speed of light (which was stated to have been increased some time ago), so their speed would be limited by relativity, but then that raises the question of how Bender went faster and how anyone could ever get around as far as they could.
• According to relativity no matter how fast you're going things can still move at the speed of light relative to you in any direction.
• These, and many other scientific inaccuracies are lampshaded in the DVD Commentary:
David X. Cohen: I wanna know how a ship can skid to a halt in outer space.
Matt Groening: Yeah, that's the future for ya...
• The same episode mentioned in the first addendum also states that the ship isn't always moving, it ''moves the universe around it". ...So yeah, wrap your head around that.
• Played straight in the episode "A Planet Blown to Pieces" of Il était une fois...... Space. The freighter in which our heroes are scaping of a star that has gone supernova is hit and damaged by debris of a destroyednote  Cassiopeian fleet sent to savage equipment and men of base in a planet orbiting it, grinding to a halt even with a puff of smoke until her main reactor has an emergency repair moving then again.

Real Life
• The Earth's atmosphere doesn't stop abruptly at 100–200 miles altitude; it tapers off the farther away you get until it's as thin as the interplanetary medium. At 200 miles high — the usual altitude for Low Earth Orbiting satellites — there's still enough ghost-fringe of an atmosphere to cause a tiny drag force. This is why satellites in Low Earth Orbit suffer orbital decay. Eventually, the satellite has to make some kind of orbit-correcting rocket burn, or it will re-enter the Earth's atmosphere and, most likely, burn to a crisp.
• Skylab was a famous example of this. Its orbital maneuvering engines ran out of fuel and, with no re-supply missions able to be scheduled before the Space Shuttle entered service, it crashed into Australia.
• In fact, there's enough air in Low Earth Orbit to maneuver. Using wings.
• In the upper layers of the atmosphere, air drag can cause a satellite to speed up. As an initially circular orbit decays, the change in gravitational potential overcompensates for the energy lost to friction—until the drag force grows large enough.
• The Soviet US-A radiolocator oceanic reconnaissance satellites required a lot of power and a very low orbit due to poor radar resolution. The huge solar panels would have created too much drag. The solution? Onboard nuclear reactors.
• Aside from the obvious need for an infinite amount of energy, one of the limiting factors in attempting to reach the speed of light is that the interplanetary medium does actually begin to have significant friction as an object accelerates towards light speed (even if it never reaches it).
• Space friction is one of the reasons why the Bussard Ramjet isn't the miracle spaceship drive it's often described as: sure, interstellar space is a near-vacuum, but when you multiply that by tens of thousands of square kilometers of intake scoop cross-section, you get a respectable amount of drag. In fact, the ramjet has been proposed as a useful braking mechanism for interstellar craft for this very reason.
• Even in the absence of other matter, photons are a source of friction in a vacuum.

## Exceptions:

Anime
• Cowboy Bebop: in one episode, the Bebop is out of fuel, but the characters are unconcerned and are just killing time while the ship coasts to its destination. Despite this, Cowboy Bebop is not entirely a realistic series using Newtonian flight physics. There are plenty of occasions where the ships behave in Newtonian-correct ways (maneuvering thrusters, braking with forward-firing engines...), but plenty more when they don't (the dogfights in space, for instance, follow atmospheric flight patterns). The dogfights, however, may get a Rule of Cool exemption.
• Outlaw Star operates similarly, but the dogfights definitely follow a more 3D style of maneuvering. In one episode, the Outlaw Star even rides a "stream of aether" using its parachutes.
• Planetes did its research. Most of the early story was about collecting debris that were dangerous precisely because items in space never slow down or stop.
• Super Dimension Fortress Macross handpicked a number of physics rules to abide by and it's pretty consistent with those, but then there are the ones it dislikes and rapes constantly.
• Infinite Ryvius is about teenagers who are trapped on a ship drifting due to inertia.

Comics
• Averted in Tintin's adventure on the moon. The rocket kept going forward even when the engines were shut off (it was mostly kept on to make an artificial gravity for the crew) and had to turn around and fire the engines towards the moon to kill all the speed they built up.

Films — Animated
• Averted in WALL•E, most notably in the space dance scene. When WALL•E uses the fire extinguisher to fly about, he kept going even after he had stopped firing the fire extinguisher and had to fire in the opposite direction to stop his movement.

Films — Live-Action
• In Aliens, it's stated that Ripley's lifepod "drifted through the core systems". The engine was off when it was recovered.
• Averted in Dark Planet. The hero's solution to a minefield blocking the path to the objective is to cut all power except life support and cool the hull to ambient temperature, then go straight through the minefield on inertia. The result is that the mines mistake the ship for a derelict and allow it to pass.
• Much of the drama in Gravity comes from the fact that an object set in motion doesn't slow down until it hits something else. This includes both space debris and the protagonists themselves.
• But Geoge Clooney's character keeps being "pulled" by an unknown force as Sandra Bullock's character cuts him loose and he floats away, when he was already "stopped" in relation to her.
• It wasn't unknown. It has to do with angular momentum and angular velocity. They were swinging on the paracord, only very slowly after they got tangled and pulled a huge length of it father away from where it was caught, which acted like a pivot. Same principal of a ballerina slowing down in her spin by extending here arms outward. If one watches the scene again, you can see them still moving upwards in relation to the ISS. And with all of that equipment they have on, it makes sense as they why he was being pulled away. Which means it's still averted.
• On the other hand, when Dr. Stone manages to reach Tiangong, the station is visibly encountering friction, because it is in a decaying orbit and skimming the atmosphere.
• Averted in Interstellar, thanks to its adherence to Newtonian mechanics. This is a relevant plot point, since this allows the Endurance to reach Edmunds' Planet following a gravitational assist from Gargantua, even after expending most of its fuel..
• In the film Space Camp, one of the instructors actually informs the students that they keep drifting unless encountering an opposing force.
• The film Armageddon references physics nicely when one of the NASA astronauts explains physics to our drilling team by pointing out that if she kicked one of them in the balls, he'd float away. "Rock Hound" asks when they start training for that.

Literature
• In Honor Harrington, plenty of attention is paid to the difference between acceleration and motion — to the point that moving too fast can leave you blazing past the enemy's fleet without time to take a shot at him.
• The longest range sensors in the Honorverse detect ships by their engines. Therefore, getting a respectable velocity going and then simply coasting from extreme sensor range to extreme weapons range is the bread-and-butter of stealth tactics. (During this process, you may as well go have dinner and enjoy a good night's sleep before tomorrow's battle.)
• Averted in George Johanssons series Universums öde (~Destiny of the universe, 1979-1986). Humanity's nuclear-powered spaceships journey through the solar system by accelerating at 1G until they're halfway to their destination where they start decelerating at the same rate, thereby solving the problem of on-ship artificial gravity. Although you would need to reverse the floor and the ceiling to ensure you're being pushed in the right direction at the midpoint, which could create some problems for furniture and such.
• Averted in pretty much every novel by Robert A. Heinlein which features space travel. In fact in many of his novels which showed fuel problems in space revolved around fuel needed to change course, to reach necessary speeds and to stop when needed against the weight of carrying said fuel. Heinlein was very good about that sort of thing.
• An interesting aversion from the Wing Commander novels. While the games themselves obey game-friendly atmospheric physics, the novels suggest that fighters and capital ships can attain indefinite speed with constant acceleration for as long as their internal fuel supplies hold out, or a sort of mind-bogglingly fast terminal velocity by employing drag scoops that collect interstellar particle matter to fuel the engines.
• Averted in the Piers Anthony novel Thousandstar, which features a race in space. The racers have to calculate the ideal halfway point to switch from maximum acceleration to max deceleration, and some who cut it too fine crash at the destination planet.
• In Earthlight by Arthur C. Clarke, an Earth passenger ship en-route to Mars is unable to turn around when war breaks out between the two planets. They have only enough fuel to slow down when they get to Mars.

Live Action TV
• Babylon 5 portrays spaceships moving realistically according to Newtonian physics, even showing damaged vessels with no engines gliding helplessly out of range of help. Ships with gravity-based technology can move in a more Star Trek or Star Wars manner; watch the White Stars dart around the comparatively lumbering Earthforce Omega Destroyers which, having no gravity-based technology, maneuver far, far more like spacecraft we have today.
• In the Stargate SG-1 episode "Tangent", O'Neill and Teal'c are stranded in a death glider without engines. They continue to travel at constant velocity, expecting to reach the Oort cloud in several years. Indeed, stolen death gliders are programmed to operate in this manner, on a course toward a planet controlled by the Goa'uld who owns them. Since Goa'uld are absurdly long-lived if not killed violently, they fully expect to recover death gliders in this manner.
• Averted in Stargate Universe; Destiny and its shuttles move in the BSG fashion.
• Noticeably in episode "Darkness", where the Destiny uses the atmosphere of a gas giant for braking when out of power for sub-light engines.
• In Red Dwarf, Starbug's engine is disabled, and they're in trouble because they're headed right at a planet and traveling entirely too fast for comfort.
• Firefly
• The cut-off-our-engine-and-coast trick is used to approach Niska's space station without being detected.
• Averted in Battlestar Galactica. Vipers can turn on just about any axis, and the visual effects always show thrusters on the sides of the fighters engaging when this happens. One of Starbuck's favorite maneuvers is to flip her Viper end-over-end to point her guns directly at the enemy fighter following her, making it so that her bird is travelling backwards. During 4x09, The Hub, the show even uses unpowered Vipers tethered to Cylon raiders to escape enemy detection before a battle. One of the pilots says "What's going to stop us when the Raider in front of us stops?"
• The reimagined BSG has several notable aversions. In the pilot, Boomer and Helo's raptor takes damage and starts leaking fuel. Boomer gets round this by shutting the engines down and letting their momentum carry them to their destination.
• Another example comes during the Resurrection Ship arc. Starbuck shuts down the engines on her stealth ship and flies it right through the Resurrection Ship on thrusters alone. She goes completely unnoticed until she powers her engines back up again, at which point she's jumping out anyway.

Tabletop Games
• Avoided in Battle Space, the space-combat game that takes place in the BattleTech universe. What makes it more confusing is that it's a 3D space game played in 2D, so you have to take notes to each ships position, inertial direction, its pitch, yaw and roll rates, usually playing on a map which is about 300 times too small for any space encounter. A movement phase for a single fighter might take up to around 5 minutes (or more if the player needs to calculate ahead a few turns, which they undoubtedly will have to), which is probably one of the reasons why the game never took off.
• BattleTech: Aerospace used acceleration and deceleration to pilot your ships. The hex maps had gravitational arrows and strength in the hexes — if you were going slower than the strength number in the hex you ended your turn in (if I remember right), you were pulled 1 hex in the direction indicated. Careful piloting could actually put your ship into a permanent orbit.
• Attack Vector: Tactical is fully Newtonian, 3-dimensional starship combat. Each ship has a ship diagram records vectors in three axes, and momentum carries from one round to another. Vectors must be canceled to change direction. Ships are tracked in orientation in three dimensions using tilted blocks in increments of 60 degrees. The Physics Equations to explain motion and heat dissipation, and everything else are in the rule book. This game system is also the basis of Saganami Tactical Simulator, the Honor Harrington space combat game, and Birds of Prey, an air-to-air modern age fighter combat game.
• Jovian Chronicles makes you track 2 dimensional vectors and has a "reality distortion level" that goes from Hard to Soft. Basically the game is Gundam in all but name.
• Noble Armada makes you track two dimension vectors as well. Going so far as making you place a d20 next to the ship stem to signify how fast, and in which direction you are traveling.
• Babylon 5 Wars actually had fully Newtonian physics, and you had to thrust in the opposite direction to slow down. You could roll you ship by assigning thrust points to "roll thrusters" on one side of the ship and canceling the roll with thrusts on the other side. With certain firing modes it was possible to damage all the roll thrusters on a given side of a ship and the main engines, meaning it was possible to have ships wildly spinning as the drove off the board.
• The Kaufman Retrograde in Star Fleet Battles is a related tactic, in which ships go in reverse to keep the advancing enemy in optimum range as long as possible, but as (predictably enough) the ships maneuver like Star Trek ships it's done by firing the warp engines in reverse.
• GURPS: Spaceships goes perhaps too far in avoiding this. Extensive (and accurate) calculations are available for people who wish to use them. It's made quite clear that with any sort of realistic engine turning it off for most of the trip will almost certainly be necessary. The existence of random debris in the void of space is mentioned but only in that if you spend enough time traveling at a good fraction of lighspeed it will wear away the hull after a few years, there's no way it could slow you down meaningfully.
• Warhammer 40K: Space Hulks are huge conglomerates of ships that are mushed together in the warp, occasionally getting spit back out into realspace and continuing to drift until they get sucked back in or fall into a sun.
• Battlefleet Gothic averts this by forcing ships to take a command check to burn reverse thrusters in order to stop. The Warp Rift unofficial rules for running on minimum power in order to avoid detection avert this, stating that ships continue on the exact same vector as they were on before shutting down unless the ship uses minimal thrusters to slow down.

Video Games
• The indie 4X game, Star Ruler has newtonian physics on all the ships. The only thing restricting ships is their acceleration speed (and fuel), meaning you can have ships zipping through star systems at a sizable fraction of the speed of light. Ships disabled from crew death, power failure, or running out of fuel will cause them to drift along their path until the game kills it after a few minutes to save processing power. If you have stations orbiting other stations, and the core station is destroyed, the orbiting stations will be catapulted out of their orbit, then fall into orbit around the star; this can lead to stations spinning around a star at insane speeds, with nothing to limit their maximum speed.
• Allegiance, a multiplayer-only space combat sim originally made by Microsoft and later made open-source and free, provides a partial aversion — a compromise between realistic physics and Space Is Air. Ships have inertia, and turning your ship will not instantly change your direction of movement. In combat, your ship will usually be facing (and shooting) in one direction, and traveling in another. Competent players will use this to great effect, but it can also be a pain when you need to come to a quick stop to avoid ramming a wayward asteroid. There's even a retro-booster that a player can fire to slow down in a hurry at the cost of fuel, and although it's a rarely used piece of equipment, some veteran players swear by it. On the other hand — and this is where the compromise with Rule of Fun comes in — there is some space friction, and turning off your ship's engines will make you slowly glide to a stop (although how slowly depends on your ship's mass, and it often isn't enough to save you). In addition, each ship model has a maximum movement speed for gameplay balance reasons in addition to different rates of acceleration, and some ships rotate faster along certain axes than others (for example, Rixian Unity ships have fast yaw, but slower pitch).
• In Sword of the Stars, Human, Tarka, Hiver, Zuul and Morrigi ships, while using some form of FTL to travel through interstellar space, use regular Newtonian reaction thrusters for tactical combat. Destroying the engine section of the ships of these races will cause them to drift helplessly away from the battle, at whatever speed they're going at, in whatever direction they're going at. They sometimes end up crashing into a planet or an asteroid, and get destroyed. Liir ships, however, don't use regular thrusters at all — they use "stutter warp" (a propulsion method involving fast, repeated short-range teleportation) for both interstellar and tactical movement. Destroying their stutter warp engines will cause them to halt wherever they are.
• The trope is even more averted by the Kinetic Kill missile, a solid-body projectile that impacts into ships at a horrid speed. A ship hit by one of those will start flying and won't be slowing down again.
• Actually, Tarka can research technology that allows them to use their hyperdrives for tactical combat by manipulating the hyperspace bubble to move the ship. Unlike Liir ships, however, Tarka ships with destroyed engines will continue coasting.
• Also, even with destroyed engines, ships are usually able to slowly get back into battle by using their thrusters.
• Averted to hell and back in the 2000 space combat/trading simulator-with-a-capital-SIMULATOR Terminus. The game uses painfully realistic physics — to the point where the extremely common fate of new players is to simply have to quit and restart, because they are drifting endlessly through the infinite emptiness of space, having burned just slightly too much fuel on an earlier acceleration or correction.
• On top of that, it also factors in relative hull strength, overall mass, and acceleration. Got your ship doing top speed and try to make a 90 degree turn? Have fun dying. Loaded cargo ships are sitting ducks and it's entirely possible to overcompensate on a docking run and hit your target. There's a lot of effort put into making sure things behave right in space.
• In Colony Wars 2, one mission has you tow a frigate out of harms way when its main engine failed; the problem is that it drifts to an asteroid and if you pull too much on the nose sideways, it'll create a torque and the sides may collide with the asteroid. Also, your own spacecraft drifts when your engine is disengaged; you'll rarely, if at all, have any time sitting put without any motion (although, you drift in a lateral motion, and like the asteroids there, you never stupidly rotate in place like most Hollywood asteroids do).
• In earlier Elite releases, physics implementation was simplified, but in the later versions of Elite by Frontier Developments it's avoided, along with other space tropes. Ships that run out of fuel will continue to drift forever through a solar system. You can even stay on an elliptic orbit (evident only with time acceleration, of course)
• Although sometimes, if you have an autopilot destination locked in, you can just hit max time acceleration and you'll arrive and dock perfectly.
• Elite: Dangerous allows you to either play the trope straight or avert it by giving ships flight-assist computers. If the flight-assist computer is off, it's averted, and if the flight-assist computer is on, it's played straight.
• Pioneer Continues in Frontier's vein. The development team have decided to stay with Newtonian, rather than Einsteinian, physics, so there's no top speed. Its behaviour is pretty close to reality for most situations, though.
• Escape Velocity gets inertia right, but a whole lot of other things wrong. Once you're moving, you can stop holding down the arrow key and the ship will continue on its current direction unless you attempt to stop it. The problems appear when you realize that weapon speeds and ranges are absolute rather than relative to the speed of the ship that fired them. This error has led to what some players call the "Monty Python Maneuver", where you run away from enemy ships, then turn your ship 180 degrees (you'll still keep moving in the original direction!) and fire at the ships. You will be out of range of the enemy while they're still in range of you, even with non-lightspeed weapons.
• Another consequence of the ability to turn in place is the carousel maneuver, which requires some very carefully timed thrusts but essentially allows you to almost orbit the enemy ship, facing them the whole while.
• There are also several inertialess drives (which are not quite the same as Friction In Space, but behave similarly). These are on Vell-os ships and the Polaris Raven, which are intangible and warp-propulsed respectively. These ships are ironically harder to steer in combat, as they cannot coast or turn in place for the characterising "joust" — they need turreted beams to avoid having to face their opponent.
• This can actually lead to your massive Polaris Raven (just about the biggest, nastiest ship out there) being swarmed and shot to pieces by groups of small fighter craft. Their small size (and thus small inertia) allow them to basically make endless attack runs whilst remaining inside the minimum range of your weapons. A ship without inertia-less drive could rotate and catch them, but the Raven simply can't.
• Independence War 2: Edge of Chaos mostly had Newtonian physics and slightly realistic scale to the systems, although shooting out the engines for some reason left the disabled ship spinning (if they were in a turn), but stopping. You could also override your ship's maximum speed, accelerating so fast that even missiles can't catch you, but consequently it took just as long to stop the ship, unless you engaged and then quickly disengaged your LDS drive, canceling all inertia and making your ship fly 1000 m/s in the direction it was facing at the time LDS was shut down. Fortunately, the ship's computer would automatically fire the thrusters to make the ship go in the direction you want it to, so you could do some Old School Dogfighting while still trying to deal with Newtonian Physics...unless you intentionally toggle off the inertial compensation.
• The original I-War also would let you turn off the computer's compensation if you wished, leaving you completely at the mercy of Newtonian physics. While it would mostly fall under Awesome, but Impractical for most players, mastering it would let you do some stunts that you'd have a hard time believing.
• One key use of inertia is to speed up in the direction you want with the help of max-energy engines, then divert all energy to weapons when you have a good PBC solution without struggling to maintain that speed. Speed is key to survival in this game.
• Zig-zagged in Shores of Hazeron. If you use eludium in your engines and they are receiving power, then your velocity is always conserved relative to the facing of the ship, which takes some getting used to. If you are drifting to starboard while facing galactic north, and you turn to face galactic west, you will now be drifting north. Thrust is therefore required to slow down, but you can change heading instantly and even spin in a tight circle. Rocket engines, however, provide a straight aversion. All ships will drift realistically when power is lost.
• In Star Control, every ship has a "maximum speed" they can reach on their own, but don't slow down without a good reason and may even orbit a planet. In Star Control II combat, this nominal maximum is easily surpassed with a staple maneuver "Leyland whip" — use of a planet's gravity to accelerate — until the ship collides with something or fires thrusters. Some collisions do the same.
• Orbiter, being a realistic spaceflight simulator, makes mincemeat out of this trope. However, it has only a Newtonian physics model, so you can theoretically go faster-than-light.
• The Settings section in the game's launcher allows you to turn off some of the realistic restraints (e.g. allowing infinite fuel).
• While Tachyon: The Fringe abuses the trope in normal flight, there is a button you can hold to continue moving in your current direction at the current speed. You can even spin around and fire backwards. A real pedant could use this system to fly the ship in a (pseudo) real fashion!
• For example, it also allows you to fire your afterburners for a few seconds and then coast along in your current direction at extreme speeds, which is terribly useful if you need to get into or out of a particular fight very quickly, or if you just get impatient.
• Another case that supports the trope is a mission to stop a capital ship whose engines are stuck from colliding with asteroids in an unusually dense field. After a while of you blowing up the asteroids, the captain of the ship will finally ask you to destroy its engine power plant. As soon as that happens, the large ship coasts to a stop within seconds.
• In Vega Strike, spacecraft behave more or less like this by default, but it's a partial compensation by the navicomputer as a convenience for Old School Dogfighting and docking — as such it's limited by the thrusters' force and eats fuel all the time when velocity changes. One key sets "Zero" speed vector to match the target's, which makes docking easy. Turn off "Combat Mode" and velocity limits raise 100x, turn off Flight Computer and the spaceship behaves more like the real world. Whether you'll want to use it in combat is a matter of style and controls — sometimes dancing on thrusters manually without auto-compensators works better. One of stock tactics is whittling foes on fast fly-by, especially efficient if their weapons are more powerful but yours are shield-piercing.
• In fact, the idea was copied from somewhat older I-War series, where it was a major gameplay feature. Complete with "dock-to-that-flying-thing-and-accelerate-it-sideways" missions.
• Also in Babylon 5: I've found her.
• In Origin's classic spaceflight sim/RPG Space Rogue you could toggle between 'Cruise' mode where (according to the manual) the computer automatically handled your main engines and maneuvering thrusters, letting you point where you want without having to manually counter-thrust to stop and apply min thrust in the new direction. You still had to fight your own inertia though. And you could turn this off completely for 'Newtonian Flight' if you so desired, allowing you to burn hard in one direction and then spin and coast backwards. This was a game breaking tactic since enemies always evade when perused, but stay locked on you if you're the one being chased, allowing you to fire away without much worry of evasion. You could also use the Newtonian Flight mode to slingshot around gravity wells...if you were really good at it.
• The trope is explained fully in an overheard conversation from Mass Effect 2, in which a gunnery officer explains that a single misplaced shot from their powerful cannon will have the same force whether the target is a mile away or 10 light years away; and this causes a big problem when that 10-light-year target is an innocent merchant vessel (he even orders the private he's harassing to fully recite Newton's first law). When traveling with the Normandy inside a star cluster or solar system, releasing the "accelerate" button makes the ship fly on inertia alone while still burning fuel to slow down. As it's also possible to fly through a sun in ME 2, one can assume it's a Viewer-Friendly Interface for how Shepard directs the Normandy to go places.
• There's a conversation Shepard has with a shop owner on the Citadel, discussing people who don't understand this trope, saying "You wouldn't believe how often I hear 'Why is the ship turning around? We're only halfway there!'"
• In the second game, Joker lampshades this trope in a bit of random cockpit dialogue.
"It takes skill to bank a ship in a vacuum. Don't think it doesn't."
• There is a bit of this in the backstory as well if you dig deep enough. In particular, the reason why a derelict reaper ship was found was due to a shot that after hitting it ended up scarring a planet lightyears away.
• The drastically underappreciated Star Wars space simulator X-Wing Alliance used relatively realistic space physics, unfortunately making stopping a nightmare in cargo-collection missions.
• In the game Nexus: The Jupiter Incident the earth designed vessels have huge thrusters on the back, and huge thrusters on the front. When you order you ship to stop, the ones in front fire like mad. In fact, you can clearly see a variety of maneuvering thrusters in operation. This is even true of the later alien vessel you get, which also has forward pointed engines (though far less obvious).
• Although the Wing Commander series plays this trope mostly straight, in the later games some fighters have the option of "autoslide", which will make your fighter operate in a purely Newtonian manner for as long as autoslide is toggled. To actually change your vector requires turning it off and going back to playing the trope straight, however, then turning it back on when you're on the desired heading and have accelerated back up to the desired velocity.
• Ace Combat 3: Electrosphere averts this in an anti-satellite mission starring an orbital fighter, and even puts the player through reentry procedure. Yes, a hard portrayal of space combat in the one sci-fi installment of a series devoted to modern air combat where the Acceptable Breaks from Reality are as numerous as the missiles hiding within its airplanes' wings. Yes, hard in more ways than one despite the objective of the mission boiling down to "gun down the defenseless, stationary targets within the time limit", because you're going to have to take a few tries to break air-combat habits, even if you're aware of this trope.
• Kerbal Space Program. Learning how to control the orbit of your ship without friction is one of the challenges of the game, especially once you need to move that orbit out of 2-D Space.
• The PC game Inner Space averts this... but since the areas you play in are kinda small, you're more likely to slam into something than coast for very long.
• In Space Run, you build components on your ship as it travels making deliveries. You can add thrusters to go faster, and if they're destroyed your ship will slow down and stop.
• In Space Engineers, friction is completely absent bar a minuscule amount at very low speeds to prevent objects from endlessly drifting. In order for a spaceship to have full control, it needs thrusters on all six faces (forward/reverse/left/right/up/down) and a gyroscope for rotation; lacking a axis means the ship must rotate to bring a thruster to bear in order to cancel out velocity in that direction. Same goes for Empyrion Galactic Survival.
• Evochron averts it with a fully Newtonian flight system. However, switching out of inertial mode has the ship's computer use thrusters to approximate space friction. The Newtonian system still underlies it all though, so manoeuvring still tends to be a bit trickier than games which play this trope straight - trying to take a sharp corner at high speed in a race will tend to result in you flying sideways out of the course, as well as the thrusters constantly using fuel for every slight movement you make.
• Affordable Space Adventures doesn't have any genuine space travel, but the Small Craft is equipped with an anti gravity system that is paired with a Decelerator, a device that serves to create artificial Space Friction to cause the Small Craft to slow down to a stop when thrust stops. The Decelerator can simply be turned off if one wants to continue moving even after cutting the thrust.

Web Comics
• Schlock Mercenary: "We are inbound to Sol at point three-six cee, traversal shielding is at fifteen percent, we have insufficient power for full deceleration, and the ship is in two pieces. You tell me what we have averted?" Though their FTL drive probably still works.
• Probably not. After all, the STIZ is still up.

### Alternative Title(s):Friction In Space

http://tvtropes.org/pmwiki/pmwiki.php/Main/SpaceFriction?from=Main.FrictionInSpace