Asteroid Thicket



"Leia: "You're not actually going IN to an asteroid field?"

Han Solo: "They'd be crazy to follow us, wouldn't they?"

Leia: "...you don't have to do this to impress me.""

- Star Wars: The Empire Strikes Back

In science fiction movies and TV, asteroids form a vast, hyperkinetic, obstacle-strewn Death Course: Enormous rocks spin like tops and whiz around all over the place, frequently even smashing into each other. Trying to navigate one is like asking a chicken to cross a busy Los Angeles freeway during rush hour: Small nimble spacecraft flown by skillful Ace Pilots (i.e, the protagonists) may be able to slalom through without getting reduced to space dust, but any pursuing enemy fighter ships will get picked off one-by-one by giant, malevolent space boulders. Any capital ship who can't just blast a path through them with its Wave Motion Gun will have to rely on their Deflector Shields to bounce the rocks off.

It's unfortunate that Real Life asteroid fields, while they do exist, don't have such a flair for the dramatic; Real Life asteroids are strewn much farther apart from each other; so far that the chance of even seeing one (let alone crashing into one) is pretty much nil; scientists have sent space probes through our friendly neighborhood asteroid belt for decades (and haven't lost a single one in the process).

Conversely, planetary rings are (relatively) much more sparse in fiction than real life --dense. Voyager 2 flew through Saturn's G ring--one of the fainter rings--once, at an angle, and there was "lots of evidence of micrometeroid hits" on the quite small 4-meter diameter probe. However, aspiring SF writers should know that these planetary ring systems are mostly made up of ice and rocks 0.01 to 10 meters across.

A subtrope of Artistic License Astronomy, Space Does Not Work That Way and Sci Fi Writers Have No Sense of Scale.

Compare Space Clouds, a trope about the similarly unrealistic portrayal of nebula in fiction; also Vulcan Has No Moon for when objects in space are visible in locations where they make no sense (either due to the science or due to pre-established canon). Also compare Conveniently Close Planet - an Asteroid Thicket could be considered "frustratingly close asteroids". A space born equivalent to an Aerial Canyon Chase will take place in one.

Anime and Manga

 * In the second season of Space Cruiser Yamato/Star Blazers, Yamato attempts to elude the Earth Defense flagship Andromeda by flying at high speed through our solar system's asteroid belt. (To his credit, Captain Gideon of the Andromeda simply flies around the asteroid belt and is waiting for our heroes on the other side.)
 * The "Cemetery Belt" in episode 6 of Heroic Age.
 * Mobile Suit Gundam does this with the Corregidor Shoal Zone, a collection of debris from decades of asteroid processing for space colony construction that have aggregated around a LeGrange point. It's a bit more plausible than most examples, as it's relatively young by astronomical standards and it's in a much tighter orbit around its centre of mass than a conventional asteroid belt. Still, while the rocks don't come whizzing out at passing spaceships, there are chunks big enough for Humongous Mecha to hide behind, when collisions due to mutual attraction should have reduced them to gravel years ago and they're dense enough to make navigation somewhat difficult, though not to the point of Wronski Feint-ing.
 * Transformers Headmasters abused this in the episode "My Friend Sixshot"
 * Starship Girl Yamamoto Yohko episode 5.
 * Episode 6 of Super Dimension Fortress Macross used the "rings of Saturn" variation.
 * Galaxy Express 999 episode 3 depicts our solar system's asteroid belt this way. Granted, the series runs on Rule of Cool, but the asteroid field isn't some futuristic device designed to look like an old-fashioned inaccurate sci-fi asteroid field... it just is an inaccurate sci-fi asteroid field.
 * In Cowboy Bebop, Earth is surrounded by an incredibly thick asteroid field. It was born when an experimental jumpgate exploded near the Moon, and a good third of it blasted into pieces, raining down into Earth's gravity field. And daily meteor showers because of it.

Comic Books

 * In the Marvel Transformers Generation 1 comic, our solar system's asteroid field is portrayed in precisely this manner; in fact, the Ark's mission was to destroy a bunch of asteroids so that Cybertron could pass safely through.
 * To be fair, although the asteroid belt is portrayed incorrectly, at this time in the comic Cybertron was said to be "Saturn-sized". This size would make the chances of a cataclysmic impact more likely (though still very low).
 * The trope is turned Up to Eleven in Fifty Two; apparently the thicket that Adam Strange, Animal Man and Starfire are stuck in has a diameter measured in parsecs. This is handwaved with the explanation that it is not a natural asteroid field, but that comes nowhere close to explaining the sheer amount of mass that is present

Film

 * In The Empire Strikes Back, Han, deprived of his hyperdrive, has to slalom through densely packed asteroids to evade an Imperial fleet. And then echoed in Attack of the Clones when Obi-Wan is trying to evade Jango Fett in a planetary ring.
 * The asteroid density from Empire is apparently nothing unusual in the galaxy far, far away. Rather, C3P0's cited statistics indicate they're all insanely-difficult to navigate.
 * The thicket is described as an asteroid field, which is presumably different from a belt in some way-- in interstellar space, maybe, and so gravitationally bound only to each other? Or the result of a recent collision having not had time to disperse? ...
 * A planet in the middle of formation? In such situation there could be plenty of flying rocks in close vicinity to each other.
 * They could have rewritten it to be the remains of Alderaan, although it would be kind of goofy for the rebel base to be in the same system as Alderaan...
 * The unreality of the Empire Strikes Back sequence is lampooned in this Irregular Webcomic. See also the page quote.
 * In "A New Hope", though, it's justified: the "asteroids" are really fragments of Alderaan, which has just been destroyed. So obviously they're everywhere.
 * Is it? To stop the pieces of planet from falling in on itself and becoming a new planet, the asteroids would have to be flying apart at close to the planet's escape velocity so even by the time Han Solo and Co. get there, they should have already scattered an awful lot.
 * So what if Alderaan's remains will eventually reform? It was never stated in the films that they wouldn't.
 * Perhaps it wasn't stated, but the scene depicts Alderaan's remains are being flung out at a rather high fraction of c. It's not coming back together. Mind you, that raises a whole host of other issues, so eh.
 * Asteroid thickets come up once in the X Wing Series, as the X-wings try to get through asteroids to an enemy ship. The enemy actually had a strategy for this situation, which was to shoot the bigger asteroids, which would destroy the fighters which are hiding behind them on their way to the big ship. Even though a pilot realized this before it happened and called them off, two were taken out on the retreat by, yes, unavoidable giant space rocks.
 * The second Rogue Squadron game had the Rogues guiding transports through an all-concealing nebula, and later going on a mission through an asteroid thicket that was very dense.
 * Interestingly, while dense, the asteroids barely move and as such, the fields are very easy to navigate. Even the bonus level based off of the Millenium Falcon chase scene has nowhere near the amount of danger implied in the film.
 * Titan AE had the characters flying through a giant ice field. We see a lot of the giant ice balls smash into each other, which at the rate they were going, they should have reduced the entire ice field to ice cubes within a few years.
 * Variation: Instead of an asteroid field, Galaxy Quest has ships traveling through a space minefield. Which makes far more sense because, as a minefield, it's supposed to kill whoever enters it, and the mines were more or less stationary until a ship got close enough to set off magnetic sensors, and close enough together that the ship had trouble staying away from them.
 * This begs the question of someone building a giant minefield In Space in the middle of nowhere. It's not as if there is a concept of a choke point in space.
 * No, but there are likely common entry and egress points to a system, and getting closer to a planet...
 * By that standard, the self-replicating cloaked mines used to close off the wormhole in Deep Space 9 would count, too...
 * Meteor shows our solar system's own asteroid belt being like this, with two large asteroids close enough that when one gets hit by a comet, a spacecraft orbiting the other gets destroyed by the debris.
 * The lunar shuttle in Airplane! II: The Sequel encounters a ridiculously dense asteroid belt after it goes off course. Made doubly ridiculous because of the way they're going: know any asteroid belts between the Earth and the Sun? Me neither.
 * Though there might be Vulcanoids
 * It's a comedy. Shush.
 * The introductory zoom-scene from Contact shows our own asteroid belt as one of these. The scene is otherwise fairly accurate on scales, however (except for the distance of radio transmissions).
 * The team that created the opening said they did it on purpose partly for Rule of Cool and partly because most people would think a fully accurate portrayal of the entire sequence would look "wrong."
 * In the 2011 film Green Lantern, the green lantern leads the Big Bad through a classic asteroid thicket. There then follows a questionably plausible sequence involving the sun. Also, the solar system is apparently ridiculously small.
 * Armageddon explains the cloudburst of meteorites as the result of a comet passing through the asteroid belt and bouncing shrapnel into Earth's vicinity, including an asteroid "the size of Texas," whatever that means. This is doubly wrong, once for thinking that a single comet could collide with so many asteroids and conveniently shove them in the same general direction, and twice for thinking that a comet (size range 100 meters to 40+ kilometers) could knock a Texas-sized piece of anything out of the belt entirely.

Literature

 * Averted in 2001: A Space Odyssey. While passing through the asteroid belt Discovery passes within visual range of one asteroid. They deliberately chose their route to bring them close enough to make observations of that asteroid.
 * This is another example of Clarke getting stuff right. When 2001 was written, scientists weren't sure if it was even possible to travel through the Asteroid Belt. In fact, this was one of the reasons why Pioneer 10 and 11 even were launched, to make sure that the more expensive Voyager probes would be able to make it. While they were wrong about the Asteroid Thicket, the probes found that the radiation produced by Jupiter would have damaged the electronic equipment on the Voyager probes. They were hurriedly amended.
 * In addition, one of the planned approaches to Saturn would have taken one of the Voyagers through the Cassini Division, which appears as a gap from Earth. Turns out it's chock fully of lovely dust that would have put an end to the mission real quick.
 * Speaking of being chock full of lovely dust: Although 2001 portrays the asteroid belt as being nearly empty of big rocks, it also describes Discovery's main communications antenna dish as being riddled with extremely tiny holes, punched by the micrometeorites that permeate the asteroid belt.
 * Averted and explained in The Martian Way by Isaac Asimov, who says that perhaps the spaceships didn't have to waste propellant to go around the asteroid belt, since, while on map it looks like a swarm of insects, it would take real stroke of bad luck in order to hit a rock.
 * Asimov's first published story, Marooned off Vesta, embodies this trope; but as explained in the 2001 example above, this is Science Marches On, not Did Not Do the Research.
 * Asimov actually reuses the "hit by an asteroid" idea a number of times, although in each case he dedicates at least a large portion of the story to explaining just how unlikely it is:
 * In The Stars like Dust, Gilbret claims he discovered  when his ship was damaged by a stray asteroid and they rescued him.
 * In the short story "Feminine Intuition", important information about a possible nearby life-bearing planet is being transported via an aircraft. The aircraft is hit and destroyed by a meteorite. Because of how improbable it is, the characters speculate as to whether some higher intelligence orchestrated the meteor strike to keep Earth from learning about their alien neighbors. The odds against this happening are astronomical.
 * Robert Heinlein said the same thing in Farmer in the Sky when the narrator observes that the 'old pile drive' ships used to 'plow right through the asteroid field and none of them was ever hit enough to matter'. Nevertheless, he had the Mayflower bypass the Asteroid Belt, to avoid even that tiny chance. Nevertheless, the Mayflower was hit.
 * In the universe of this book, the Asteroid Belt is more densely packed than it is in Real Life, as it's stated a couple times that the Belt used to be a planet. This is a case of Science Marches On; it was once thought that the Asteroid Belt might have been a planet that broke up, until we discovered there's not nearly enough material in the Belt to have ever made a planet-sized object.
 * Justified in Tobias S. Buckell's Halo novel The Cole Protocol. The Rubble is explicitly said to be very unusual, the asteroids having been tethered together, and is kept stable by constant adjustments controlled by an AI.
 * With the outer colonies glassed by the Covenant, it seems Insurrectionists have chosen to colonise asteroids instead, as the crew comes across one in First Strike.
 * Subverted in Allen Steele's A King of Infinite Space, where the protagonist claims to expect the asteroid field to mirror his recollections of Empire Strikes Back, only to discover the scientific reality of the asteroid field.
 * Justified and lampshaded in Crusade by David Weber. It first comes up in the context of a closed warp point (a warp point without a significant/detectable gravity field) that happens to exist in the middle of an asteroid belt, which led to the immediate destruction of small ships transiting due to collisions - a situation immediately stated as freakish and unique. One chapter later, an enemy uses an asteroid cluster in a different star system to hide a fleet, while musing that only in a handful of clusters do "conditions even approach those... in popular entertainment."
 * In Timothy Zahn's Vision of the Future, when the Wild Karrde goes through an asteroid field, Karrde notes that it's more dense than most his crew has encountered, as they have to shoot down asteroids more or less constantly. Zahn, as a general rule, knows quite well how space works and writes accordingly. But Asteroid Thickets are the one thing that showed up in Star Wars and could not be explained or handwaved, so he uses them like anyone else.
 * Luke Skywalker And The Shadows Of Mindor features Luke and his task force making plans to attack a base on a planet, Mindor. This planet had a sister planet very near it not at all long ago, but during a superweapon testing the sister planet was destroyed, and the debris was largely pulled around Mindor in a configuration that was too unstable to be called an orbit. This resulted in the planet becoming largely uninhabitable and the space around it acquiring an "asteroid storm"; capital ships appearing in it had a one-in-fifty chance of being hit by a big rock immediately, increasing incrementally as time went on.
 * Completely averted in Larry Niven's Known Space universe. Larry is well known for Showing His Work. Belters are explicitly described as spending months at a time alone, flying their singleships between asteroids on prospecting runs. He even extrapolates and uses the ramifications in his stories. Not everyone has the kind of personalty to handle that amount of nothing for the length of time that is required to get from place to place. The ones who can't never come back to port. Belter society is made of the ones who can.
 * Future Hope features a cocky, crackerjack space ace whom the author attempts to characterize as the greatest in the solar system by describing how he was famous for being the only pilot to ever safely navigate through the asteroid belt without his navigation tools on.
 * It's strongly averted in Stanislaw Lem's Tales of Pirx the Pilot. The protagonist's ship was maneuvering in an asteroid cloud for several hours without actually seeing one asteroid. This trope is also lampshaded when a panicking passenger who doesn't know much about space wonders why the captain isn't trying to evade the asteroid cloud, and then declares the captain insane when he is told the asteroids aren't dangerous.
 * Averted in Lacuna. Liao hides the ship in the Solar System asteroid belt and Summer complains about how it's a terrible place to hide because it's so empty.
 * The Boneyard in the Star Trek the Genesis Wave series. The titular wave, an Interstellar Weapon, is launched from a base concealed within it.

Live Action TV

 * Battlestar Galactica. Guilty as charged. Rather surprising given that it's usually relatively accurate when it comes to astrophysics.
 * Might have been justified when they were in the debris disk around the black hole. Every other instance, however...
 * Actually, the 'asteroid field' in Scar was argued to be a protoplanetary disc, because the science advisors or whatnot knew that asteroids weren't packed together but still wanted a dangerous dogfight situation.
 * The Blakes Seven episode "Mission To Destiny" features a space storm that appears as an asteroid thicket. An interstellar one.
 * The pilot (episode, not the character Pilot) of Farscape had an asteroid thicket.
 * In the Peacekeeper Wars wrap-up mini-series, Braca leads a fighter squadron through a planetary ring in order to strike at the rear of the Scarran battle fleet. Plausible (not the thicket) in that radiation would keep the squadron's approach masked from enemy sensors.
 * The Lost in Space episode "The Reluctant Stowaway" (the premiere) featured the Jupiter 2 being pummeled by asteroids as it drifted off course into the belt.
 * The 2007 4th season premiere of Stargate: Atlantis has Atlantis, shot into space in the previous season, having to make its way through an asteroid field. Sheppard, McKay, and a team have to shoot the asteroids into pieces to clear a path. Sheppard, trying to reassure McKay, compares it to the video game Asteroids. McKay responds, "But I was terrible at Asteroids! I think I actually scored zero once!".
 * Star Trek
 * The Star Trek the Original Series episode "Mudd's Women" shows the U.S.S Enterprise chasing Harry Mudd's stolen ship through an asteroid belt (at relativistic speeds) where the asteroids are seen to zip past the Enterprise (as seen by the bridge screen that Kirk is looking at). The asteroids appeared to be spaced apart from each other at considerable distance rather than the traditional Star Wars type asteroid thicket.
 * In the 7th season episode "Genesis" of Star Trek the Next Generation, the Enterprise sends a shuttle craft into an asteroid field because it was too dense for the Enterprise to go in safely. It was mentioned that the asteroid field was unusually dense though. This was by far the least significant scientific inaccuracy in this episode, where the crew 'de-evolved'.
 * In a 7th season Star Trek Deep Space Nine episode, Odo tries to hide from some Jem'Hadar by flying into a dense Kuiper Belt, which aside from trading comets for asteroids, is still a classic Asteroid Thicket.
 * In the Voyager episode "Year of Hell," the beat-up ship hides in a nebula... and suffers from gas leaking in, implying that it's denser than the ship's atmosphere.
 * Part of the race course in the Stargate SG 1 episode "Space Race" goes through what appears to be an Asteroid Thicket composed of house-sized chunks of ice.

Tabletop Games

 * The Star Wars-Risk boardgame used an impenetrable asteroid field to represent planets destroyed by the Death Star, rendering travel in the region.
 * Twilight Imperium features asteroid belts that take up the same amount of space as a star system and pose a serious problem for the movement of certain classes of starships.
 * The Asteroid fields in Battlefleet Gothic are an Egregious example, probably caused by the target audience expecting "terrain" to fight around. The effects of asteroid fields are thus: Anything unguided (a space hulk, torpedoes and so on) are automatically destroyed upon entry. Attack craft have a 1 in 6 chance of destruction and full space ships (from escorts to capital ships) must take a command check, and if failed can take crippling damage in a single instance.
 * Eclipse Phase actually manages to avoid this. There are asteroid fields, but they're exactly as they are in reality.
 * In Star Fleet Battles, asteroid fields are thick enough so that any ship or seeking weapon passing through them has a significant chance of taking damage, possibly enough to destroy it. They also interfere enough with sensors to allow ships and bases to hide within them.

Video Games

 * The X-universe series of games plays this trope straight 90% of the time; one sector has about 80 asteroids (about 1-2km in diameter) crammed into an area about 80km on each side. Most sectors have much lower concentrations, but even those have 3-10 asteroids in a sector, which have only 80-200km between the two pairs of jump gates.
 * One must mention the classic arcade game Asteroids, where the asteroids just go through each other: either they cheat, or their dodging skills make them smarter than the player.
 * Clearly the player's ship is actually a huge arrow-shaped tower.
 * It's worth noting that some Asteroids clones do feature collision detection and the asteroids will carom off one another.
 * The first set of starship battles in Ratchet and Clank Going Commando take place in such a region, though again this may be justified by the fact that it seems to be gathered around a possible mining station.
 * On the other hand, Ratchet Deadlocked has a planet whose orbit takes it through an asteroid field so dense, the residents put up a planetary shield so they didn't get Colony Dropped to death.
 * The Meteo area in the Star Fox games. "Use the boost to get through!"
 * The classic Space Sim Wing Commander and Free Space both used this trope, the former as a Death Course for fighters. The latter creates a very distinct mix of infuriating and awesome by making the asteroids too slow and clumsy to be a threat to fighters, then having missions where a desperate capital ship plows through them and has its small craft play point defense against the Malevolent Asteroids that continually appear out of nowhere to converge on the target ship.
 * You think that's bad? Try a game breaking bug that prevented the capital ship from jumping to safety at the end of that very mission...
 * Wing Commander is worse than FreeSpace as it features mines as well as asteroids. In either game, you can shoot rocks out of the way. In Wing Commander, if you shoot a mine, it goes boom--violently--and you will probably die.
 * And then, you got the bug in Wing Commander (the SNES game) where if you shoot an asteroid or mine miles away from the Tiger's Claw, you get the "Tiger's Claw Blew Up and You Drift Forever!" cutscene. Thankfully, there was also a Good Bad Bug where you could dive or climb just far enough to make asteroids go off screen. Doing so, makes them disappear from the game oddly enough.
 * Freelancer carefully examines this trope. First, due to their thickness, most asteroid fields in the game are hiding places for criminals. Second, also due to their thickness, several asteroid fields are also suitable for mining operations. Third, some of these asteroid fields are actually made of junk (one of them is even a minefield!). And finally, the spacecraft manufacturers must be very aware of the difficulty of navigating these places by hand, because in order to get across an asteroid field, you just have to set a waypoint to your target, press the Go To button, and the computer will do the slaloming for you.
 * Which is a very bad habit to form if also playing the above mentioned X-universe games, where letting the auto-pillock fly in an asteroid field is suicide.
 * The Escape Velocity series (plays like Privateer, looks like Asteroids) has immensely thick asteroid belts, but ships cannot collide with them. Their purpose is simply to interfere with weapons fire (though they can also be mined in the third game).
 * These asteroids are identical in appearance to those in Maelstrom, a clone of Asteroids which was Ambrosia Software's first published game.
 * In Homeworld, one mission puts you right in the center of a swarm of malicious asteroids, your objective being to get your smaller ships out of harm's way while blasting apart asteroids that are about to collide with the Mothership. There's a margin for error in that the Mothership can handle a few hits, but it's still not quite as easy as it sounds.
 * Averted, actually. The "asteroid storm" is the result of exiting hyperspace in the tail of a humongous comet. They were supposed to show up in the gas tail, but miscalculated and ended up in the debris field. It's still a touch iffy, but if we're talking a cometary body that's hundreds of kilometers across and it's on an approach vector to its sun, then it could be in the process of breaking up. The "asteroids" couldn't be harvested until blown apart, suggesting they were icy bodies.
 * In another mission, a large asteroid is deliberately steered into the path of the mothership (via a huge engine built into the asteroid's "back"), as it cannot change direction when in hyperspace, and will automatically exit hyperspace when a potential collision is detected.
 * The enemy aliens actually used hyperspace inhibitors to yank the Mothership and its fleet out of orbit. They knew the approach vector of the Hiigaran fleet and where they were headed, so it wasn't too difficult to get an inhibitor and headshot asteroid in position for an attack. The kamikaze fleet run afterward was a headbanger moment but....
 * The various Star Wars-based space sim/shooter games tend to have at least one mission with a whack o' asteroids, probably in deference to Episode V, though in this case the asteroids tend to be much less harmful in and of themselves (though they might prove to be excellent platforms for a starfighter hangar, well-defended space-base, or weapons turrets).
 * Empire At War uses them as well; large ships will usually fly around them to avoid losing shields.
 * Stage 3 of Shadows of the Empire has the Outrider trying to escape from the Empire in an asteroid field, but Dash leaves the piloting to Meebo, so the player really doesn't even have to think twice about them.
 * The PS3 downloadable title Super Stardust HD has asteroids that swoop down, and then start orbiting around the planet you're guarding. This appears to be because of an incredibly powerful planetary shield whose existence is for some reason entirely dependant on the existence of your ship.
 * The backstory explains that the asteroids are being thrown at those planets by the attacking aliens to distract you when they attack.
 * The MMORPG Eve Online suffers from this trope in that of the 5000+ solar systems, a large majority of them have at least one "Asteroid Belt" orbiting a planet, and some have upwards of 20 or 30. This alone isn't enough... the asteroid belts themselves are composed of a belt maybe 100km from end to end with asteroids of various mineral types densely packed together; in some cases the asteroids are so large and so dense that avoiding their collision boxes is an exercise in futility. This is mostly due to decade-old design decisions. The asteroids are used for mining by players, and going from one rock to the other in a realistically sparse asteroid field in clumsy mining vessels would be very annoying to say the least. Various modifications and reforms to asteroid belt realism and the interactivity/fun of mining in general have been floated by CCP over the past few years, but so far they appear to be on the back burner. Finding a fix that doesn't destroy the economy is bound to be problematic.
 * Avoided in the classic 1984 space simulator Elite and its sequels. Whereas the first game had several classic examples of Did Not Do the Research such as no star system containing more than one planet and one sun, it did, more or less, bang asteroids on the head. As the game was randomly generated, it was not unusual for players to never come across an asteroid ever when playing the game!
 * In the sequel Elite: Frontier star systems were more realistic, usually having several planets of various sizes.
 * Averted in Super Metroid and Metroid Fusion: the Ceres Research Lab is stationed in the middle of an asteroid field (possibly the Asteroid Belt, given the name of the station) and the asteroids therein are completely static in relation to one another, if densely packed. In the sequel, Samus only crashes into an asteroid because the X Parasite infection had knocked her out.
 * Averted in Darkstar One, where navigating an asteroid field is pretty easy, with the asteroids being large, slow and very dodgeable. The only marginally difficult part is entering into special asteroids to collect pieces of the Darkstar.
 * Justified in Dead Space, as the thicket is actually the debris kicked up by the mining ship the game takes place on pulling a continent-sized chunk out of the planet it's orbiting.
 * Doomsday Zone from Sonic & Knuckles teaches us that there's a dense asteroid field in Earth's orbit. Who knew? Barely room to fit a hedgehog between the rocks, even.
 * In the classic TI-99/4A game, Parsec, asteroid belts are unusual indeed. The game is a Horizontal Scrolling Shooter, where you fly a ship around the planet. Despite this fact, you encounter asteroid belts regularly! And each "belt" contains an identical pattern of asteroids, starting with a huge column of rocks coming at you. Each subsequent belt comes ever faster, which suggests they should have crashed into each other ages ago.
 * Edge of Chaos has this in spades. The asteroids will blow up like bombs if you shoot at them a few times. There was even a mod that turned this up to 11 by making the asteroids fly around at ridiculous speeds, pelting everything like a space hail storm.
 * Then there's also Zanac and Zanac Neo. Thick asteroid field can be seen in arer 5 in the original and thicker one is in the second stage of Zanac Neo.
 * In Evochron Legends most asteroids are clumped together, with 10-20 asteroids in a 10x10x10 KM area. Some solar systems however, have asteroids very thinly spread out across the system.
 * Mass Effect averts the dense nebula version; the Horse Head Nebula is home to various chunks of the story and sidequests, and its perfectly livable. The Serpent Nebula the Citadel sits in appears to follow this straight, but the Codex entry lampshades the improbability of such a dense nebula, notes that it makes navigation (and therefore, external attack) extremely difficult outside the perimeter of the Citadel's mass relays, and cites an in-universe theory that the Citadel itself creates and maintains the nebula artificially with its waste disposal systems. Oddly, the Serpent Nebula can't really be seen from the surface of Bekenstein, a habitable planet some distance away from the Citadel; it is, perhaps, so close to the edge of the nebula that the gasses have thinned out.
 * The one that contains Omega, however, is unexplained.
 * Omega was broken apart several centuries earlier by an impact with another asteroid. The asteroids that surround it are probably remnants from the impact - but they should have drifted away by now, unless the mass effect fields that protect the station have some sort of effect on them.
 * The end sequence of Mass Effect 2 also manages to create an awesome asteroid-maze sequence with fewer scientific issues. When the Normandy goes through the Omega-4 relay, it emerges in a frequently-replenished junkyard of wrecked ships that have passed through without the proper preparations and run into things.
 * Conquest Frontier Wars has plenty of these, conveniently on the edges of map, these thickets slowed down ships travelling though them.
 * The manual explains that the fields in the game are just representations of what is actually going on, and that the ships slow down in order to navigate through the field (the slaloming is not actually shown in the game). The nebulae are even weirder with their strange abilities (knocking out shields, decreasing weapon effectiveness, hiding entire fleets, etc.).
 * In Star Control, every single space battle, no matter where it occurs features a ridiculous amount of ship-sized asteroids. They are continually spawned to maintain a stable number, never lose momentum, and are sometimes spawned aimed directly at your ship. Fortunately, they can't actually hurt your ship, unless they bump it into the planet (another feature that's always somehow present regardless of where the battle takes place). They can be a major nuisance for the slower ships that need to spend quite some effort to get going in any specific direction.
 * If you fight a battle in an asteroid belt in the Space Empires games, they tend to damage missiles and fighters heavily. They can even damage capital ships in strategic movement sometimes.
 * In The Babylon Project, the raider bases are generally located here.
 * Halo Reach's introductory cinematic at one point passes through a very dense ice belt. A collision between two ice bodies can actually be seen as the camera moves onward.
 * Averted in Master of Orion II, where battles in asteroid fields don't actually feature any asteroids. However, the fact that blowing up a planet with a Stellar Converter and then rebuilding it with a colony in the same system can result in a larger and richer in resources planet than the original. So, apparently, a planet is more than the sum of its parts.
 * In the original game, however, the tactical battle map in some systems had squares randomly occupied by asteroid patches. Ships can't pass through them, and any missile clusters trying to pass through one of those squares get their count reduced, potentially turning a One-Hit Kill salvo into one that does little more than tickle a ship's passive defenses (shield/armor).
 * In Millennia Altered Destinies, the first probe to be sent to the Outer Solar System gets destroyed while passing through the Asteroid Belt. The technicians then apologize for not anticipating how dense the field is and claim the next probes and ships will fly above or below the belt. Interestingly, this does not add to the travel time. The Belt is also used for Asteroid Mining.
 * In Space Quest V: The Next Mutation, the crew of the SCS Eureka is forced to evade the SCS Goliath and hides the ship in a nearby asteroid field. While the asteroids are not shown moving or colliding, they do spin quite fast and appear to be close together. When Roger is forced to go EVA to rescue Cliffy, there is a mini-game that requires the player to navigate the EVA pod. However, the asteroids are only in the background and do not pose a danger.
 * Most of the gameplay in Starscape involves shooting moving asteroids and collecting the resources that appear in order to research and build better weapons and ships.
 * Ships passing through asteroid fields in Haegemonia: Legions of Iron get slowly damaged, possibly from micrometeorite strikes.

Webcomics

 * Drive. Skitter loses a pursuing Continuum ship in one.
 * Subverted, in that it's not your typical Space Is an Ocean thicket - they could easily go around it, and it's only dangerous because they're navigating it at FTL speeds.
 * Far From Home: for scouting.

Web Original

 * Invoked in the AH Dot Com the Series episode The Machine, in which Captain Dr. What (whose knowledge of how the universe works is mainly based on old movies) tries to hide from the Vendetta in an asteroid belt, and the most knowledgeable GBW keeps trying to point out that the asteroids are too dispersed for this to work.
 * In Pay Me Bug, Tyrelos Station is surrounded by the debris from a recently (in astronomic terms) destroyed moon.

Western Animation

 * Futurama's episode "A Flight To Remember" lampshades this. Zapp Brannigan deliberately makes a "course correction" to the safe flight of the pleasure cruise to take the spaceship through an asteroid field. After several near misses with asteroids, he then pilots the ship directly into a black hole.
 * Comets. They were comets, "The icebergs of the galaxy". Y'know, 'cause it was the Titanic.
 * In "Love and Rocket", Leela is having to swerve about like she's driving on ice whilst piloting through a field of asteroids.
 * Well, this is Futurama we're talking about. The Planet Express never seems to show regard for the Laws of Physics. Or a lot of other laws, for that matter...
 * That's not fair. Futurama does not endorse the cool crime of robbery.
 * Invader Zim had this in one episode. Zim piloted a ship into the asteroid belt during a dogfight with Dib and it was destroyed by the asteroids. They were, respectively, piloting Mars and Mercury.
 * The episode "Little Girl Lost Part 1" of Superman the Animated Series very neatly and subtly averts this one. While scanning the shattered remnants of Krypton, which have slowly begun forming into an asteroid belt, he receives a distress call from just outside the system. Rather than play "Asteroids" in his protective ship, he simply drops down and ducks under the field to get there as quickly as possible.
 * Averted/lampshaded in the Family Guy adaptation of The Empire Strikes Back when Threepio (played by Quagmire) says in the asteroid scene "Sir, the odds of successfully navigating an asteroid field are 2-1!". To which Han (portrayed by Peter) replies "Never tell me the o-oh... well that's not bad. Never mind, let's keep going."
 * This happens in the first episode of The Transformers, where going through an asteroid belt causes the Autobots and Decepticons to crash on Earth.
 * Star Trek the Animated Series episode "The Pirates of Orion". The title opponents' ship flees into an asteroid field that consists of a large collection of rocks close together. There are so many asteroids that it's easy for the Orion ship to hide among them.

Real Life

 * Until the Pioneer 10 space probe passed through the asteroid belt, nobody really knew how dense the belt was. Only several thousand big lumps had been spotted up to that time, but there was a well-founded worry that the craft would be peppered with impacts from many small or tiny rocks. Luckily Pioneer (and all later missions that went beyond Mars) met with nothing whatsoever.
 * And there's the DAWN spacecraft whose mission is to explore the asteroid Vesta and after that go to the minor planet Ceres.
 * At least one extrasolar asteroid belt has been discovered, with measurements indicating that it's much more densely packed than our own.
 * In its earlier stages of development, the Solar System had a lot of debris floating around crashing into each other and eventually forming the inner planets. The Late Heavy Bombardment was the final cleanup of this debris by the inner planets absorbing them via impacts, the craters of which can still be seen on the Moon and Mercury. However, even this hodgepodge would have been extremely thin compared to its fictional counterpart, with the "cleanup" taking hundreds of millions of years.