Imagine an alien race. They are the creators of Unspecified Advanced Alien Technology™. One day they lose one of their ships. The crew had to evacuate, and the ship kind of crashed on a random planet. About four thousand years later, humans found that crash site, and found a few artifacts that they managed to reverse-engineer.

These artifact are: a FTL drive core and an artificial gravity generator core. Those are the only two things that need to survive. They may be encased in a box, they may be made of indestructibium, whatever. What matters is that they survived against the elements.

How are these devices functioning in the first place? Unspecified Advanced Alien Technology™. Essentially you have a core. You feed that core some electricity and a signal, and then it does stuff based on the signal.

How did the ship survive the crash? By using some sort of foam-airbag-thingy. The ship was engulfed in that, which allowed it to survive entry and the crash. Then the thingy degraded, so it couldn't have protected the ship for very long.

Are the devices functional? Not really. There are in one piece, give or take a few bumps. They were in a good enough condition that they were taken apart, studied and copied; but not in a good enough condition to be working.

The question is:

What kind of materials could survive for that long unattended?

We assume nothing was destroyed by the impact, however since then a lot of stuff has stopped functioning. We'll limit to materials that exist on Earth, or materials that can be manufactured using materials that exist on Earth. The fancier the materials, the better. I'm looking for a few types of materials that could be reasonably used in complex machinery/electronics.

If your answer is none, then what kind of materials would survive the longest, and for how long?

As a bonus question:

Where should the ship crash in order to be buried?

The burial can take anywhere between 0 and 4000 years, but it has to be completely buried. The ship is the size of an attack submarine. I'm looking for biomes in general, not specific world locations. Bonus points if you can tell how deep it'll be buried. You can also take location into account when answering the main question.

  • $\begingroup$ See Deep Time by Gregory Benford. He covers this in detail. $\endgroup$
    – JDługosz
    Commented Jul 13, 2016 at 14:42
  • $\begingroup$ or Inherit the Stars by James P. Hogan $\endgroup$ Commented Jul 13, 2016 at 19:10
  • $\begingroup$ Twinkies. And it'd be buried anywhere you find a lot of sedimentary rocks today. $\endgroup$
    – WBT
    Commented Jul 13, 2016 at 19:19
  • $\begingroup$ I mean, as long as its on an atmosphere-less barren planet, possibly with a thin layer of reflective dust covering it to protect from the nearest star, I cant imagine anything that would significantly degrade interior components. Could be wrong though. $\endgroup$
    – James T
    Commented Jul 14, 2016 at 7:20
  • $\begingroup$ @JamesTrotter A planet without an atmosphere, unless it is tidally locked to its star, will see extreme temperature swings between the sunlit and dark sides. Compare for example the answers to Can I borrow a lunar rover? on Space Exploration. $\endgroup$
    – user
    Commented Jul 14, 2016 at 10:54

11 Answers 11



Consider a species that had a shortage of lead and for some reason decided to use granite as a radiation shield1 to protect their main drive (or from their main drive) and their computer core.

Granite is good stuff when it comes to surviving through millennia. As long as it actually survives the impact, it'll still be there in a few thousand years. It's resistant to acid, pressure, erosion, oxidation and time in general.

Anything encased inside your granite case is going to be in a protected environment and unlikely to be affected by anything other than temperature change. Sealed in granite, it's going to still be there a lot more than 4000years later.

1 Study the Attenuation Coefficient of Granite to Use It as Shields against Gamma Ray

  • 29
    $\begingroup$ So what you're saying is that, even after millennia have passed, you can just take for granite that it'll still be in good shape? $\endgroup$ Commented Jul 13, 2016 at 15:38
  • 10
    $\begingroup$ @MasonWheeler I granite you there would be some weathering if it was on the surface all that time but the OP said it would be buried. $\endgroup$
    – Separatrix
    Commented Jul 13, 2016 at 15:53
  • 2
    $\begingroup$ +1 for using stone-age materials in a future technology context. Perhaps we should dig up the Acropolis and other ancient sites... Stonehenge? $\endgroup$
    – user17228
    Commented Jul 14, 2016 at 2:36

A non-Answer Answer: Avoid the question entirely.

FTL is essentially time travel, it must work in a way that disrupts time. As part of normal operations the FTL core envelopes the entire ship in a time-dampening field.

With the crash, two things happened:
1. The FTL core was not properly shut down and has still been generating the field.
2. The ship power plant, or power transmission was crippled so that it could not fully supply the FTL with the power it needs to maintain full field strength.

The net result is a field that is slowly diminishing in size leaving the parts of the ship further from the core effectively exposed to the ravages of time longer than those closer. This continues until the time dampening field shrinks to the point of excluding the power plant so that it finally succumbs; cutting off the FTL core power and the remaining field suddenly fails.

This has the benefit of leaving those that discover the ship remains with the mystery of an oddly decomposed corpse. The ultimate failure of the power supply could occur relatively recently so that the area immediately adjacent to the core is left in near pristine condition while the extremities have completely eroded away.

The power supply failure might even lead to the discovery of the ship due to explosion or radiation spike from venting its remaining fuel.

  • 2
    $\begingroup$ "FTL is essentially time travel, it must work in a way that disrupts time." Nope. study the real-world concept of the Alcubierre drive, space and time are entangled in relativity, you can simply fold space around you and appear to an outside observer to be moving at faster then light, while technically still moving slower. You don't need to mess with time for that. A gradual time dampening field has tremendous implications for heat tansfer etc. and will likely not work out (stuff would overheat and explode due to different conduction/convection rates etc.). $\endgroup$
    – Polygnome
    Commented Jul 14, 2016 at 12:09
  • 8
    $\begingroup$ @Polygnome “real-world concept” and “Alcubierre drive” don't exactly go well in a sentence. While Alcubierre uses serious scientific calculations, it's still very much a speculative technology, and more likely than not it is impossible to “simply fold space around you”. If FTL is possible in your story, then it is no more a stretch to also assume that it slows down time itself than to assume it doesn't. (Note that this is still not really time travel.) $\endgroup$ Commented Jul 14, 2016 at 15:24
  • $\begingroup$ ...whereas I don't see what you mean by the implications of gradual time dampening. A time-damped cell would just act like a very good thermal insulator, WRT heat conduction. Styrofoam also doesn't explode, just because it doesn't conduct heat well... more relevant are issues like collecting an enormous number of solar neutrinos in the slowed-down area, but that also needn't be catastrophic. $\endgroup$ Commented Jul 14, 2016 at 15:33
  • $\begingroup$ @Polygnome I didn't mean the field itself had gradual effect (I'll revisit my wording as I can see it could be taken this way), rather a sharp edge, it is the effective size of the field that shrinks. Everything inside being equally damped, everything outside unaffected. True there would be an event horizon of sorts at the edge of the field where we might run into real problems, but for the purpose of the story maybe this helps as the receding edge passing through parts of the ship speeds their decay. $\endgroup$
    – Mr.Mindor
    Commented Jul 14, 2016 at 15:36
  • $\begingroup$ @Mr.Mindor: actually I'd reckon a sharp cutoff is far more problematic. Physics always gets more troublesome if there are discontinuities, for instance you'd get crazy reflection modes from particles that aren't really supposed to interact with matter at all. If the slowdown transition is smaller than an atom radius, you'd heavily meddle with the energy states of all matter – this could well cause huge explosions, or at least complete wreck all the materials. $\endgroup$ Commented Jul 14, 2016 at 15:39

4000 years is not that much if the crash site is a good place.

I think Antartica is the best place. There is no liquid water that can deteriorate the metal. Protected inside the ice we may never find it. If the ship is not obliterate by the crash the inside is safe for a very long time for humans are almost never there.

If the energy is provide by a fission nuclear core it can melt the ice that's bad if the ship fear rust (of course a advanced alien civilization is capable of making an inoxydable ship).

You can keep the core in a pressurized box made of multiple layer of slow aging materials like polymers, titanium (corrosion resistance of titanium : http://www.azom.com/article.aspx?ArticleID=1336 )

With those condition its almost easy to last 4000 years.

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    $\begingroup$ Even better might be crashing in/on a glacier. Old things keep popping out of those. Perhaps more spot-on example of a WW II P-38 that was buried in the Greenland Ice Sheet for 50 years (although it was not exposed): Glacier Girl. Note that this plane was flown again (after some restoration) and it is planned that others buried in approximately the same place will be raised, restored, and flown again. $\endgroup$ Commented Jul 13, 2016 at 21:55

To survive for millennia you need materials that do not, or very slowly, interact with their environment.

The environment itself is significant because of that. You can have:

  1. Sand desert (covered by sand due to wind, less common that rock desert by far!)
    Most materials will survive as there is no water to make your treasures interact. Initial impact damage is your starting point. Being unattended without maintenance and time, and damage due to drying out are the factors here. Even fabrics and paper may survive. Metals should, especially gold. Stone will, if persistant to acid.
  2. Soft ground (impact will bury your ship) Usually soft grounds are moist, which is bad news for most metals. Still, peat bogs are able to preserve especially soft tissues for millennia.
  3. Ice (snow will cover, and to remain buried you'll need a gletcher of Greenland/Antarctica size)
    Ice is good news for most materials, although anything holding freezing fluids will perish. These perishables will be broken but can be researched or even reconstructed as long as nothing else happens. As long as the ice does not wrangle your ship it will largely be...OK.

The iron eating life on the Titanic shows that under water is not an option. Neither is an atoll looking at the scant leftovers from Amelia Aerhart's crash 100 years later.

References: (apologies for the gruesomeness of some)

  • 10
    $\begingroup$ Stop spreading the "glass is a liquid" myth. "The earliest archaeological evidence for glass manufacture in China comes from the late Zhou Dynasty (1046 BC to 221 BC)."link. Roman cage cup from the 4th century AD link "Claims that glass panes in old windows have deformed due to glass flow have never been substantiated."link $\endgroup$
    – Hackworth
    Commented Jul 13, 2016 at 11:03
  • 6
    $\begingroup$ Glass is most definitely not fluid, the reason why stained glass windows often have thicker bottoms is just because it was difficult to make the glass very uniform and the builders chose to put the thicker glass at the bottom for increased stability $\endgroup$
    – Annonymus
    Commented Jul 13, 2016 at 11:52
  • $\begingroup$ Glass is liquid => Just no $\endgroup$
    – Rigop
    Commented Jul 13, 2016 at 12:17
  • $\begingroup$ To make everybody happy, these aliens don't use glass, whatever it is or isn't. $\endgroup$ Commented Jul 13, 2016 at 13:48
  • $\begingroup$ @Hackworth, Annonymus, looked it up, and the effect exists but needs about the age of the universe to take effect. Clearly not of any effect in mere millennia. Removing. $\endgroup$
    – Bookeater
    Commented Jul 13, 2016 at 13:49

Self-healing materials.

It could be a special resin with the ability to cure itself, or a layer of nanomachines.

Editing to add further explanations:

A common problem faced by materials over time is exposure to changes in temperature or ultraviolet radiation. This can cause surface cracks that eventually become holes.

In the same way the skin exists to protect what's underneath and when it suffers damage is repaired by filling the wounds, the surface we want to protect may be covered with a layer of special resin that flows into the scratchs and only the surface hardens when it's in contact with the air. They are already materials which behave in a similar way.

The alternative is a layer of nanomachines mimicking a crystaline structure that only consumes energy when it has to be rearranged to cover any damage. Something like a living diamond layer.

  • 2
    $\begingroup$ Hi Daniel, could you put a little more detail into your answer, as you're quite dependent on the link you've put in and links have been known to expire. $\endgroup$
    – Separatrix
    Commented Jul 14, 2016 at 11:29
  • $\begingroup$ I hope that now the answer is better understood $\endgroup$
    – Daniel
    Commented Jul 14, 2016 at 15:01

A side note on surviving the "crash": even with rudimentary control systems, abandoned aerial craft can survive a crash landing under the right circumstances.

The amazing story of the Cornfield Bomber

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Even today's airliners are advanced enough that they can actually fly an entire route from take-off to after landing on their own (given that someone programs their flight management system for it), and recover on their own from flight upsets that a pilot is left bewildered and disoriented by.

And since this alien craft is obviously much more advanced then our paltry machines, it is more probable than not that this alien machine can recover from the emergency that cause these aliens to abandon it, and then come to a relatively soft landing. It might even have had a (semi) intelligent programming that purposely makes it choose an uninhabited area (like The Greatest Desert or the Antarctic) to stay hidden.

When it comes to surviving for a long time... well here you are free to choose. Since the tech is alien you can make up anything you want. Given that the power-plant survives and can be run for a long time — suppose for instance it is a fusion reactor that has, say, half a ton of fuel left — and the ship employs self-repairing techniques then those that discover the ship may find it in a state as good as new.

  • $\begingroup$ As for aircraft that can fly on their own, compare Helios Airways flight 522. $\endgroup$
    – user
    Commented Jul 13, 2016 at 14:08
  • $\begingroup$ This answer assumes that the alien craft values aerodynamics as much as we do. If they can generate artificial gravity and have warp speed, what makes you think the craft even has wings? And if it doesn't, it'll just fall right out of the sky like a rock. $\endgroup$ Commented Jul 14, 2016 at 20:02
  • $\begingroup$ @DrunkenCodeMonkey What is your point here? If it is needed that the aliens value aerodynamics... TA-DAH!!! ...author just made it happen. This was not even my main point. My main point was that auto-land is not even sci-fi tech... it exists already today. And stories about abandoned craft surviving until they are found exist since hundreds of years back, and even with aircraft. So that an abandoned craft can survive un unattended landing is plausible. $\endgroup$
    – MichaelK
    Commented Jul 14, 2016 at 20:59
  • $\begingroup$ The point was that in an airplane if the engines go out you still have lift from your wings. That's the only reason you can crash land them. Wings are useless in space. Wings are also useless in an atmosphere if you have anti-gravity. If the anti-grav goes, the ship would not crash land, it would crash straight down and probably vaporize on impact. $\endgroup$ Commented Jul 14, 2016 at 22:15
  • $\begingroup$ @DrunkenCodeMonkey I am sorry but right now you are just spouting irrelevant what-if's to try to shoot down the idea. The author can technobabble up anything he wants to let this craft go down safely, all right? You are completely missing the point here... $\endgroup$
    – MichaelK
    Commented Jul 14, 2016 at 22:17

If you have advanced nanotechnology that lets you place individual atoms and manipulate bonds, you could encase whatever you want in a solid diamond. I think it would be great to have a phone like that, virtually indestructible. Doped carbon can even be a semiconductor, after all it resides in the same column of the periodic table as Silicon and Germanium. Until the manufacturing process improves to the degree that the aliens have it, it would be difficult to mass-produce nanotechnology, but you could possibly reverse engineer how it is designed using advanced techniques not required for manufacturing. As the manufacturing processes improved, more advanced or efficient forms of the devices could be created.


All you need is for the hull to remain intact throughout the crash. That's relatively easy even if the antigravity drive is marginally functional. I'd probably assume the crew is all dead prior to the crash and the automatic systems are all fluttering on the point of failure. The craft won't have any interesting aerodynamic properties (wouldn't need it with antigrav) so it'll fly like a brick when antigrav is off. But even being active for a few moments during descent could preserve the hull.

A space ship's core function is to provide a stable environment inside, regardless of extreme conditions outside. Even without active environmental controls a buried ship's atmosphere would remain stable basically indefinitely. (As long as the aliens solved the pesky problem of rubber, if not you've got a hundred years tops before all the air seals fail -- even then if it's buried in a sand dune, by then you might be protected enough for the cores to survive)

Crashing in an arid climate would solve the problem of the hull rusting through, but honestly so would building the craft out of non-reactive metals. Aluminum springs to mind since aluminum oxide forms a super strong clear coat which protects the underlying metal quite nicely. Titanium is nice and strong (though brittle) and benefits from being very light. Not that you need to worry about that since you have antigrav.

I would go ahead and assume that an advanced alien race would combine metals into very interesting alloys. Metals which were light and strong, non reactive etc. Consider stainless steel, it wasn't till the industrial revolution that it was commonly available. Compared to cast iron it's a super metal, but really it's just a minor tweak. An advanced civilization will have thousands of such tweaks. Transparent, ultra strong ruby glass, metals which are light and strong, non-reactive radiation proof. (we're starting to be able to make all of the above)

Soil accumulation will be different in different environments. The Sahara for example has very low soil accumulation. There's basically a set amount of sand and it moves around. Other deserts have higher soil accumulation due to soil deposits from the surrounding environment. This book looks cool. Extreme Depositional Environments: Mega End Members in Geologic Time


One warning about microelectronics or just about anything with very small parts (nanometers). Atomic or molecular diffusion across boundaries between different solid materials is a very slow process up here on the macro-scale, although mechanics will occasionally have to separate components that have pressure-welded themselves together. However, the rules change for the micro and change dramatically for the nano.

A modern microprocessor chip is unlikely to function after 50 years in storage, regardless of how well the container lasted. After 4000 years it may not be possible to deduce anything much about the microchip at all.

  • $\begingroup$ That's only true for MEMS devices, chips containing electro-mechanical devices. For transistor arrays, which comprise the bulk of the area on modern processor chips, the rate of diffusion of the doped areas is about 1nM per 316 million years @ 125C. If you choose very tiny miniaturized geometry, 1nM may be a problem. Otherwise it is pretty insignificant at room temperature. You are far more likely to have serious problems with the capacitors and resistors and/or memories after only a few decades/centuries. Properly packaged ICs will likely last thousands of years without issue. $\endgroup$ Commented Jul 15, 2016 at 18:45

most plastics would, as nothing has yet evolved to decompose plastics, as until very recently (on an evolutionary scale) there has been no need to

same goes for concrete and most metals

meaning even if it took this alien species thousands of years, and we'd all killed ourselves off, they would probably be able to tell that something evolved on our planet

on a separate note: @JDługosz

FTL does not require warping the passage of time, for instance, the theoretical Alcubierre drive (look at Wikipedia if you don't know what this is), relies on effectively compressing time infront of you while expanding space behind you, nothing to do with time, but theoretically reaching super luminal speeds

  • $\begingroup$ Most industrial plastics consists of organic compounds mostly made of carbon, oxygen and residual elements. Most of these substances are sensitive to sunlight, and albeit they did not decompose completely, they often get weak, porous or harden to some extend where they easily shatter or crumble to dust by small forces. $\endgroup$
    – dronus
    Commented Jul 14, 2016 at 15:30
  • $\begingroup$ I know that most plastics are poly ethane, or similar compounds, sometimes with additional elements like fluorine, but because they did not exist in nature, there has been no reason for anything to have evolved that could decompose them, so plastics WOULD survive $\endgroup$ Commented Jul 15, 2016 at 10:19
  • $\begingroup$ Nature doesn't require bacteria to get rid of plastics. Erosion over long periods by sand and wind is likely to go through thin plastic relatively fast in combination with photodegradation. $\endgroup$ Commented Jul 15, 2016 at 18:51

Another non-Answer Answer that might actually get you the results you're looking for: what if the highly-detailed User Manual for these artifacts was stored in some sort of highly resistant material?

Diamond has, probably, little to no practical use in the artifact itself, but one could imagine big diamond crystals on which optical tricks permit storing terabytes of data.

Such a crystal could easily survive an impact, and spend millenia in almost any environment without degrading. For us humans, a perfectly cubed diamond would be closely scrutinized and its use as optical storage would be easily discovered. Translation would take a while though.

At that point, you don't necessarily need the FTL drive and antigravity to survive mostly intact. If you have, say, the Engineer's Guide to Field Repairs for these items, then even remnants, as long as they're not completely turned to dust, would make reverse engineering quite easy.

  • $\begingroup$ I considered writing about diamond as well, but then found it's actually pretty useless. It doesn't like high temperatures or shocks and has the wrong electrical and thermal properties. $\endgroup$
    – Separatrix
    Commented Jul 15, 2016 at 7:31

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