For any spacecraft which travels through the Earth's atmosphere, there's a critical thing which needs to be considered beforehand. Space travel is fast, and hitting the atmosphere at the kind of speed you'd have in orbit will make your spacecraft hot. Very hot. Atmospheric friction takes the form of a supersonic shockwave as the air can't flow out of the way fast enough and is superheated by the resulting compression. If you attempt to plow through the air without sufficient shielding, disaster could (and indeed, horrifically, did at one point
) occur.
It's fairly common for fiction to ignore this little inconvenient fact, because it means characters and impractically designed spaceships can get onto (or off) a planet without burning up. It simply doesn't include an atmosphere. In some cases, Applied Phlebotinum is used (Deflector Shields are a common method for sufficiently advanced sci-fi cultures; shields that can block a nuclear weapon can usually also handle reentry), or the ship simply slows down before reentry to avoid burning up. The latter isn't necessarily too unrealistic for a ship which is using nuclear engines, or otherwise doesn't need to worry about fuel (or balancing fuel consumption with arrival time). If you have enough energy, cooling, and propellant (the latter two are still needed until the air itself becomes dense enough to be useful), you can move as slowly as you want, but "enough" here is really big. The issue for all current orbital spacecraft is that they need to use most of their fuel to lift fuel (not crew or payload) to the altitude where it will be burned, and a ship that used its engines to slow down would be much more expensive since it'd have to carry even more fuel.
Note this trope does not generally apply to anything with Anti-Gravity or similar propulsion systems as such craft would be able to hover over a planet instead of needing to orbit a planet. Orbital rings, shells, elevator or anything else in geo-stationary orbit are also generally exempt as there is no need for them to move at hyper velocities to avoid crashing back down onto the planet. Craft that are in the process of taking off may or may not be exempt if they have not yet accelerated to orbital velocities or if they do not gain any horizontal velocity to escape a planet's orbit.
Also note that the heat of reentry could be safely eased by entering an atmosphere slowly. Writers can say the ship is going slowly as it reenters, but this is also creates Real Life issues too - it would require a lot of power to do that. You're going to need to counteract gravity with thrusters and fuel (which also create heat, and add to the fuel the spacecraft has to carry) or "repulsor technology" (doesn't exist in reality), then deal with the fact that an atmosphere can be 200 miles (320km) thick (that's Earth, loosely) so if you've slowed down to 200mph (160kph) you've still got an hour-long trip down to the surface.
Contrast Friction Burn, which is the opposite of this trope, and Reentry Scare. Compare Soft Water, a similar problem with using water as an all-purpose safety net. See also Spaceship Slingshot Stunt.
Examples:
- Wonder Woman: In Wonder Woman (1942), all sorts of spacecraft, space debris and people entered and fell into earth's atmosphere and the heat caused by friction was never once depicted or alluded to in any way.
- Evangelion: A New Awakening: Invoked when a technician warns the base's Deep Space Radar Tracking has picked up two huge high-speed objects, approaching from space, and expresses surprise at the computer prediction that they will not burn up on atmospheric entry.
- Aliens. The dropship's entry into the atmosphere of LV-426 apparently causes no heat buildup at all.
- The Sulaco is a starship, it has enough power and fuel to enter or exit the gravity well at will so it's not limited to orbital velocity. At the time the Cheyenne drops from it, the Sulaco's speed is not stated but it's clearly not so fast that atmospheric entry is a problem for the dropship —in fact, it drops vertically using gravity to accelerate and then fires thrusters to gain additional speed. This clearly implies that the craft was moving significantly slower than orbital velocity, presumably slow enough that atmospheric friction wasn't an issue.
- In Fantastic Four: Rise of the Silver Surfer, a Friction Burn is just what the Human Torch needs, as catching fire allows him to fly. Ironically, he fails to catch fire until he is well into the troposphere.
- Flight of the Navigator: The ship flies up to the edge of the atmosphere and back down again at multi-Mach speed with no heat or friction effects. Justified because of its advanced technology.
- Zig-zagged in Star Trek Into Darkness. The Enterprise is in freefall after the damage the Vengeance has caused and the ship starts burning up. Sulu even says that, without the shields, they'll burn up — you see panels being torn off as its in freefall. However, the Enterprise ultimately doesn't burn up — it's heavily ravaged from all the shit it went through, but it's still flyable. Even worse, when the Vengeance zips pass mere seconds later, it isn't even harmed at all!
- Star Wars Expanded Universe:
- In X-Wing: Starfighters of Adumar, it's noted that an X-Wing's shields protect it from reentry. Thus, Wedge can maintain a higher speed on his entry to Adumar's atmosphere than the unshielded Blades escorting him can.
- During the very first X-Wing book, Corran actually uses a planet's atmosphere to damage a TIE fighter by luring it close enough to the planet during a dogfight to cause reentry heat to begin building up (TIEs do not have shields, unlike X-Wings, so this could destroy it).
- Other parts of the SWEU, including some books in the same series, use the friction of atmospheric reentry in various ways. Attaching extra hulls to burn up during the descent lets a squadron of X-Wings disguise itself as part of a meteorite shower, letting them infiltrate a hostile world. In the New Jedi Order, the Wraiths have developed single-person reentry pods with ablation shielding for basically the same purpose.
- In Han Solo at Stars' End, the Millennium Falcon uses its shields to offset the heat of entering the atmosphere of Duroon.
- An aversion in Before the Storm leads to a Red Shirt moment. During a military exercise, a fleet tender drops out of hyperspace too close to decelerate before hitting atmosphere and is lost with all hands.
- The Corellian Trilogy sees a New Republic Intel agent crashing her ship on Corellia, noting as she does so that most ships are designed to survive the heat of a ballistic re-entry - but only once. They're intended to have functional engines to slow them down before they hit the atmosphere.
- Use of Weapons: When a Culture module wants to make a swift getaway from a planet's surface, it displaces (teleports) away the air in front of it to behind it as fast as it's moving. It thus makes a multi-mach trip to orbit through a nice, frictionless, self-created vacuum. Of course, The Culture are Sufficiently Advanced Aliens.
- Star Trek:
- In the Star Trek: The Next Generation episode "The Arsenal of Freedom", this is averted when Geordi uses the friction from atmospheric reentry to expose a cloaked drone harassing the Enterprise.
- In Star Trek: Voyager, Voyager is able to land on planets without this ever being a problem. Averted in the "Equinox" two-parter, when the captain of the Equinox directs his ship into the atmosphere of a planet, knowing it would tax his shields. Voyager follows, suffering the same, only they are also being harassed by extra-dimensional aliens constantly assaulting their shields, so Janeway has to give up before the shields fail.
- You wouldn't normally expect scientific accuracy from Warhammer 40,000, but Space Marine Drop Pods do have to have heat shielding and stabilizer systems to survive reentry.
- Although played straight with most of the other vehicles, which look about as aerodynamic and shielded as a block of candyfloss and which somehow manage to be SSTO spaceplanes and floating cathedrals. Semi-justified given the advanced materials used in their construction, and because there seems to be one school of thought in Imperial engineering and that thought is "Thrussssssssssssssst!!!".
- To be fair, all these flying cathedrals were never intended to actually enter atmosphere. They have shuttles and drop pods for that.
- Although played straight with most of the other vehicles, which look about as aerodynamic and shielded as a block of candyfloss and which somehow manage to be SSTO spaceplanes and floating cathedrals. Semi-justified given the advanced materials used in their construction, and because there seems to be one school of thought in Imperial engineering and that thought is "Thrussssssssssssssst!!!".
- A stock ending for Sonic the Hedgehog games is for Sonic to fall to the planet after blowing up a space station. Sonic 2 shows Sonic actually fly to space on the outside of a ship. Sonic Adventure 2 partly corrects the astronomy by making it possible for characters to die if they hit the atmosphere (Eggman even uses it in an attempt to eliminate Sonic). However, the atmosphere's height varies according to how high the platforms above it are.
- Not really. All that changes is how long until your character appears to enter the atmosphere- and it has to do with how many platforms are below you, in order to give you a chance to return to a lower part of the stage.
- That being said, there has been no case in the entire series of an organic character falling from the upper atmosphere to the troposphere without being in a vehicle designed for it or tapping into the reality-warping power of the Chaos Emeralds to protect them. It seems ascending is just fine in the Sonic games, but descending is always lethal. The endings of Sonic 3 & Knuckles and Sonic Advance even show the invulnerable, non-breathing Super Sonic and whatever objects he's carrying encounter some atmospheric friction as he's falling back down.
- Super Mario Galaxy, obviously.
- Most of the Kirby games are like this.
- Zig-Zagged in Star Trek: Bridge Commander. Moving too close to a planet will cause an orange, fiery halo to appear around your shields - even if your shields are down - until you splat into the planet. No matter how fast you're travelling, though, you'll never burn up or suffer damage unless you actually hit the planet. Given that planets in this sector are about 200km in diameter, they don't have very thick atmospheres.
- Surprisingly, Orbiter plays this halfway straight, despite being very realistic in most respects. There's friction on reentry (enough to bounce you back out of the atmosphere if you enter at the wrong angle) and a visual effect to show heating, but it's impossible to destroy a ship this way. A few modded vehicles avert this trope.
- Most HSD spaceships in Rank Amateur are designed to be aerodynamic so they can aerobrake without getting damaged. Human/Earth Authority ships are either designed either with landing capability or to never enter atmospheres. The latter type would burn up on atmospheric entry.
- The less said about the Professor's wooden spaceship that takes the Castaways to Gilligan's Planet the better.
- Study of the Moon has revealed that yes, the moon indeed has an atmosphere, albeit a thin one. That means that all of the (successful) Apollo missions technically Played Straight, then Averted, this trope in succession.
- NASA engineers say that Mars is a particularly annoying planet to try landing on, because it has enough of an atmosphere that you have to deal with it when descending into it at orbital speeds, but it's not thick enough to actually be useful in deceleration.
- Someone falling from very Low Earth Orbit (but relatively stationary in respect to the surface below, so they fall almost straight down) would hit a maximum speed of 800 miles an hour and then begin slowing due to air resistance, a speed that an aircraft or even a spacesuit with modern materials would have no problem dealing with in terms of frictional heating. The main problem with the idea of orbital height skydiving is that it's easy for the friction at such high speeds to induce a spin or tumble which could cause the diver to black out or be injured or killed due to the g-forces involved. Some kind of drogue parachute, however, which could stabilize the skydiver and slow them down slightly, is entirely feasible.
