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A scene in my story involves the main character encountering a crashed spacecraft while collecting firewood for his village, and keeping it a secret for several months. The spacecraft is about 20 meters in length, and has among other things an Expanse-style fusion drive, meaning fuel and delta-v are mostly not a problem. Its only crew member and pilot is dead by the time the main character finds the ship.

While I currently describe the spacecraft to be an old but functional relic, I'm considering rewriting the scene to make it crash land while the main character is out and about, in order to better foreshadow a later event in the story. However, any spacecraft that re-enters an atmosphere from orbit would, in my understanding, probably be seen by the entire village, and the main character still has to keep the ship a secret for the sake of plot.

Is there any way for this crash landing to only be seen, or not be dismissed as a natural phenomena, by the main character? I'm open to giving the ship far-future or theoretical technologies to help with this, as the story's setting is largely a space opera.

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    $\begingroup$ Depends . is their Somebody Else's Problem field turned on? $\endgroup$
    – Pelinore
    Sep 14 at 8:39
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    $\begingroup$ You probably meant "discreetly" rather than "discretely". I think that a spaceship could crash very "discretely", in that it will probably end up a bunch of discrete small pieces rather than a single, vaguely defined wad or smear. $\endgroup$ Sep 14 at 15:36
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    $\begingroup$ If propulsion were still functional so that it can decelerate, and the only thing wrong was that the pilot couldn't control fine maneuvering, then it might be discreet. Think "747 comes in for a landing and the landing gear is screwed". That's a scary landing for passengers and not some tragedy. But if propulsion were scrammed, that's the red phone to Putin to make sure he's not nuking, not to mention nothing from the craft survives. $\endgroup$
    – John O
    Sep 14 at 15:50
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    $\begingroup$ Is this world technologically similar to our own? If so, the space of possible solutions changes significantly. $\endgroup$
    – Yakk
    Sep 14 at 18:46
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    $\begingroup$ Q: should the ship survive, be functional after the crash ? the pilot died, but what are your plans with the space ship ? will your main character leave the planet flying it ? $\endgroup$
    – Goodies
    Sep 15 at 18:39

13 Answers 13

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Why does the crash have to be a fiery comet from space?

The ship could have safely landed due to a medical issue with the pilot. The ship might have sucked a duck into the engine intake while hovering and fallen a short distance. The ship may have landed automatically after the crew got wiped out by a radiation blast. The ship's AI may have vented atmosphere and fled it's builders. It might have crashed during a storm.

There are plenty of reason why an (mostly?) intact ship could be alone on the ground with nobody seeing it land.

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    $\begingroup$ That’s a great point about the different ship malfunctions—I never actually considered a slow landing! I originally had in mind a dramatic, fiery encounter, but I think I’ll go with the post-radiation-blast automatic landing, since it’d probably leave the ship the most intact. Thanks for the answer. $\endgroup$ Sep 14 at 6:11
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    $\begingroup$ It's home planet doesn't have birds - so the engine was never designed with bird strikes in mind :D $\endgroup$
    – Christian
    Sep 14 at 14:05
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    $\begingroup$ Add to this that if the cloaking device was still in effect (as well as the autoland function) then the controlled descent would have been hardly noticed at all. $\endgroup$ Sep 14 at 15:51
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    $\begingroup$ It can even be a post landing malfunction. Something is supposed to be shut off by pilot post landing. Or a vent or sensor get obstructed/bent during the landing. Pilot is passed out. Thing in question overheats/get mangled. By the time action is taken it's way too late and whatever got destroyed isn't field-repairable. A small aircraft equivalent would be a bent landing gear or prop. Nothing dramatic, but still can't take off anytime soon. $\endgroup$
    – ptyx
    Sep 14 at 16:38
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    $\begingroup$ @RossPresser THANK YOU GRAMMARBOT 3000. PROLONGED USE OF UPPERCASE IS CONSIDERED RUDE. PLEASE AMEND PROCEDURE 4672 FORMAT_OUTPUT(STR) USING AMENDMENT 4672-LC. $\endgroup$
    – user253751
    Sep 15 at 8:37
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There are a couple different things that make a mess when a spaceship lands: the fireball that streaks through the sky, the engine firing/parachutes deploying, the smashing into the ground.

The most noticeable of them is the fireball, which is a ball of plasma that creates sonic booms as it goes by. Getting through this violent process is why spaceships have heat shields. If you had infinity delta v, you could slow the ship down before reentry, and basically skip all the fireball in the sky plus not have a heat shield. Additionally, if the ship were to crash because of it's engines quitting, it would have no landing burn and noise, it would merely smash into the ground at terminal velocity.

A large object falling at terminal velocity would make a large impact cloud unless it hit something that held dust down, like a dense forest. The ship would still spend a good couple minutes falling in full view and make a thudding noise when it hits the ground.

Basically, an expanse style ship can crash land in theory with only a dull thud, assuming all the right conditions are met.

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    $\begingroup$ Note that a lifting-body spacecraft can land at potentially quite low speeds even without engines. Terminal velocity isn't always terminal ;-) $\endgroup$ Sep 14 at 9:04
  • $\begingroup$ @StarfishPrime: Or you go for broke and suppose that the ship has anti-gravity. If you want the ship to be malfunctioning, you could just have the ship wait too long and then decelerate way too fast just before it would hit the ground... which could easily be enough g's to kill a human even if the ship doesn't actually crash into the ground. $\endgroup$
    – Kevin
    Sep 15 at 2:10
  • $\begingroup$ USE ITS (NO APOSTROPHE) FOR POSSESSIVE, IT'S (APOSTROPHE) FOR CONTRACTION (thx to Ross Presser) $\endgroup$
    – Neil_UK
    Sep 15 at 10:27
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    $\begingroup$ @Neil_UK: Please do not SHOUT at people. (Yes, Ross Presser did it first. But it was wrong then, too.) $\endgroup$
    – Kevin
    Sep 15 at 18:48
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It all depends on the reentry trajectory: if it happens over oceans and scarcely populated areas there will be not so many eyes seeing it.

Keep in mind that the "glowing" part of the atmospheric reentry takes place in the upper layer of the atmosphere, when the landing site is still far away. Then there is the supersonic bang which can be mitigated if the spaceship has some sort of automated landing control.

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Perhaps the crash was during a thunderstorm and/or a meteor shower, so the sound and light show were less distinct (and sensible people were home in bed anyhow). And in fact maybe the thunderstorm and/or meteor shower contributed to the crash.

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  • $\begingroup$ I was thinking volcano, but thunderstorm at night is much more generic and perfectly sensible. Who would be out and about, at night, under heavy rain, with lightning striking left and right? Only a ~~madman~~ main protagonist. $\endgroup$ Sep 15 at 14:58
  • $\begingroup$ So I was curious and did a little research. As far as I can find, the space shuttle / Saturn V, etc. were somewhere in the 110-130 dB range for a ground observer (taking off -- they'd be quieter while landing). The X-59 is supposed to be 75 dB at ground level. Thunder can hit 110+ dB, so it's reasonable that a spaceship 10 or 20 miles from the village could still be supersonic but sound like a thunderclap, or be drown out by the clap. I can't find data on wind itself, but it seems likely even strong wind could overpower the crash noise from behind a mountain or similar. $\endgroup$
    – MichaelS
    Sep 16 at 2:51
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Crash it earlier

The main character doesn't need to see the crash, unless it's for further plot reasons. The ship can have crashed years or decades ago. That is why it looks functional but old.

It's late

The time can reduce the amount of people seeing it. It can ve so early in the morning that next to no one sees it, or is clear enough to pinpoint a crash site. It would be interesting to some to check out a meteorite, but the few who do see it might not take the time and effort to do so. Except the main character out of curiosity.

Visibility

Storms with thunder, rain and snow. Hurricanes and tornadoes. All can be valid reasons the crash isn't witnessed or heard.

It is difficult to go there/private property

If it crashes in a difficult area, like a swamp or certain mountains, it can be difficult for others to go there. Alternatively it strikes private ground. Lots of grown ups repect that, not entering the ground. At most you have to say "yeah something came down. Nothing left but a small crater". Even if kids find it, who is going to believe their 'wild fantasies'? Your main character can have all the time in the world if it strikes his farmland, some inherited piece of land outside the city, or his backyard.

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  • $\begingroup$ I was going to say it lands on the other side of a mountain. If your protagonist is a shepherd or hunter who's on the other side of the mountain from his village, he'd see it and nobody else would. $\endgroup$ Sep 16 at 0:38
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If crashes are a regular occurrence, because the orbit of the planet is/was being used as a breakers' yard and, if still active, low value hulks/components are often allowed to degrade in their orbit until they crash, or if inactive because the whole yard is slowly crashing out. Or there was a space battle in the system at some point and the debris has been hitting the atmosphere for years. Then it's not that your protagonist is the only one who noticed they're just the only one who bothered to go and have a look at the crash site. Most people who chase after crashing meteors on Earth find that if they go over the visible horizon that's the last you'll ever see of them. The locals have learned the same lesson, they'll investigate/use material that they find, or that lands in their laps but they don't bother looking for it. The pilot could be long dead, his body automatically preserved by the onboard systems. If you need to ship functional after a crash the same repair systems that have preserved the dead pilot can rebuild the broken hulk over a period of time.

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  • $\begingroup$ low value hulks/components - Was that a Thor: Ragnarok reference? $\endgroup$ Sep 14 at 19:52
  • $\begingroup$ @DarrelHoffman Not a deliberate one but I can see where it comes in. $\endgroup$
    – Ash
    Sep 15 at 10:11
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As someone with more than 300+ hours in Kerbal Space Project, I can tell you that there is a lot of potential for catastrophic failure of a landing during its final moments.

To take an example from real life, check the Soyuz TMA spacecraft, which the IIS crew uses to return to Earth. In its final descent it uses parachutes to slow down to ~7m/s (24 feet per second) according to NASA:

The main chute slows the Soyuz to a descent rate of only 24 feet per second, which is still too fast for a comfortable landing. One second before touchdown, two sets of three small engines on the bottom of the vehicle fire, slowing the vehicle to soften the landing.

If those engines fail, you are too close to the ground to try some backup measure. Hitting the ground at that speed is equivalent to falling from a height of 10m (~33 feet). I like to imagine that the Soyuz is prepared to cushion that impact internally for the astronauts, should the rockets fail. Still, the spacecraft will be damaged in that case.

You can see the landing rockets in action in this video, around the 0:10 mark. But if you blink, you will miss it. The rockets worked alright and the astronauts were all OK. If the rockets had not worked properly, then the capsule might have been damaged beyond repair and the astronauts might be anywhere between somewhat jolted to dead.

Your spacecraft might have had a similar landing, but its landing engines failed at the last second.

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The ship crashed during a heavy snowstorm, your character was out hunting/finding a lost sheep/a more nefarious reason and got caught in the storm.

No one else was dumb enough to be out and so your character was the only one to see the crash.

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The spaceship landed perfectly normally,
it just was using Apple Maps, and was setting up for a soft landing at 3200 ft ground altitude, when it discovered that actual ground altitude was 3250 ft.

That's a gentle but devastating crash, much like parking your car 30 feet into your 25-foot long garage.

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For reference, here's a Progress launch, just a small cargo capsule, viewed from the ISS: https://www.youtube.com/watch?v=ouBfzCgXHgk

The booster engines make it a bright, easily visible moving light from the moment it leaves the ground, and at around 36 seconds, the reentering booster makes that look dim, actually noticeably illuminating a large patch of Earth's surface.

That's just a low suborbital reentry of a booster stage. A full orbital entry will be much more energetic...here's a bolide that came down over Russia in 2013, breaking windows and setting off car alarms: https://www.youtube.com/watch?v=fBLjB5qavxY

As for a slow powered descent: first, that's a very wasteful approach even with a high-performance fusion torch. Second, such a fusion torch drive would make the chemical booster engines on that Soyuz look like nothing. A long, slow descent on jets of fusion exhaust might be more noticeable than that Russian bolide.

In short, given the amounts of energy involved, returning spacecraft are not likely to be very discreet. Your best bet is for the landing to be obscured by poor weather, or perhaps for the villagers to be distracted...perhaps by wreckage that came down more visibly elsewhere?

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Your shipped turned out to have soft landed on a small comet. That comet unfortunately then crashed into the Earth. After the fire ball stage of re-entry the spacecraft fell off what ever was left of the comet. People will assume it was just some bit of the comet.

What remains of the comet continues on wards and crashes a long way away. Thus when people go looking for the comet fragments, they are somewhere else, very far away from the spaceship.

Might still require some sort of low visibility event (at night, during a storm etc) for people to not completely see the spaceship when it falls off the comet and just dismiss it as bits of the comet.

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Soft, stealthy landing at orbital speed

The alien ship has a surface capable of reacting at very high resolution. It models the incoming atoms in real time, focuses an electron emission array at them to ionize them, and guides them into channels that pass through its infrastructure to the other side, where the electrons are removed and they are sent on their way. Thanks to "regenerative braking" at the ionic level, the air the ship passes through leaves with the same momentum and temperature with which it arrived. As a result, the ship can simply fall through the atmosphere at tens of thousands of miles per hour, consuming no energy and leaving no visible trace. No one sees much.

When the ship reaches the ground, it continues the same process, but its ability to process material is overwhelmed by the density of the solid earth and the velocity it needs to travel. It brakes as rapidly as it can, uses emergency power to collect excess material ahead of it and eject it through an emergency channel behind as a fiery exhaust, and comes to a stop deep below the Earth. It is linked to the surface by a hole since it did not reconstitute all of the material it passed through, and traces of heat from the emergency exhaust may prevent exploration for a short time afterward.

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Bad FTL exit

One issue that you might want to consider is that the spaceship could be noticeable well before hitting the planet. Most forms of propulsion are highly visible, so if the spaceship needs to decelerate before hitting the atmosphere then any NASA-like agencies would be likely to notice it.

Douglas Adams humorously presented another problem people often don't consider:

Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space.

If you don't have FTL, you're really limited to a single star system. The closest star system to Earth is the Alpha Centauri at 4.37 light years away. That means without FTL you cannot get there in less than 4.37 years. Additionally, even with an impossible 100% efficient engine, relativistic kinetic energy dictates that in order to get close to the speed of light the amount of energy you need to spend approaches the energy equivalent of the mass of your spaceship. The break-even point is around 0.86 c, where for every 1 kg of spaceship + remaining fuel you've already used up 1 kg of fuel that you've converted perfectly to energy and propulsion.

Unfortunately, fusion is only able to convert about 0.7% percent of its fuel from mass into energy. This changes your break-even point to a little under 0.12 c. So to get to the nearest star system you're looking at a journey of close to 40 years instead.

So if you don't want your story limited to a single star system, you really need some form of FTL. This also gives you an easy way to have the spaceship's crash be hidden - the spaceship didn't exit FTL when it was supposed to. Instead of coming out of FTL outside the atmosphere and being able to use its fusion drive to enter a stable orbit, it came out of FTL close enough to the ground that it crashed. The engine could have fired long enough for it to be visible only close up and left the ship mostly intact but the crew dead.

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