15
$\begingroup$

My world is a very distant post apocalyptic society on earth after the destruction of some orbital mega structure around the planet - like an orbital ring or something. The current civilization(s) on the planet are not aware of the old earth as it was so long ago, as the only relic of old earth is the orbital debris field surrounding the planet that has settled into a planetary ring of sorts.

My question that I’m finding it hard to answer is whether optical telescopes of say an early 1800s level society would be powerful enough to observe the pieces of debris to any measurable degree - like could they see if it is pieces of some structure up there emblazoned with the NASA logo, for example? Or would it just appear like moving lights like how a satellite zips by today?

$\endgroup$
5
  • 6
    $\begingroup$ The current answers make some big assumptions about the size of your debris. Can you help us out by specifying what remains? You say it was a megastructure, so to me it seems likely that there would be pieces with dimensions on the order of kilometers, or at least hundreds of meters. But those are just guesses; I don't know what the structure was or how it was destroyed. $\endgroup$ Commented Jun 21 at 16:49
  • $\begingroup$ @BrendanMitchell "an orbital ring or something" sounds to me like a ring-shaped structure that encircles the planet. $\endgroup$
    – Tom
    Commented Jun 22 at 19:05
  • $\begingroup$ An orbital ring (at least the version I'm familiar with) is a cable that loops around the Earth at higher than orbital speed, which can then support platforms that are stationary relative to and anchored with tethers to the surface. You then use those tethers as space elevators. If this is what OP meant, I doubt that the ring can stay intact unmaintained for thousands of years, and if it somehow did you'd also expect people on the ground to be familiar with the tethers. But most likely it would have long collapsed, leaving little to no space debris (but devastating the areas it hit) $\endgroup$ Commented Jun 23 at 13:23
  • 1
    $\begingroup$ How distant? There's a very big difference between "a hundred years later" and "ten thousand years later". $\endgroup$
    – Luaan
    Commented Jun 24 at 7:03
  • $\begingroup$ ISS and docked Space Shuttle can be seen (as a recognizable shape) wit the naked eye in good conditions. Even with a relative low magnification telescope or binoculars (or camera zoom-lens in my case) you get a quite clear picture . So the debris doesn't have to be really big. Just have an unnatural man-made shape to it. $\endgroup$
    – Tonny
    Commented Jun 24 at 11:16

5 Answers 5

17
$\begingroup$

They can, but for different reasons

It can be plausible that they can find an exceptionally large piece left over with a logo or something. However, looking into space is relatively difficult compared to looking at the ground. The ISS has dropped a battery pack to Earth and it was expected to burn up in the atmosphere. It didn't. A part hit a house, causing quite some damage. It wasn't yet clear it was the battery. They needed some research. That being said, even in the 1800 they should be able to come to the conclusion it was crafted.

Though the megastructure will have splintered into a billion pieces and caused a Kessler syndrome for a long time, it is statistically likely that larger parts have survived. Over time their orbits can decay, causing them to fall back to Earth. This makes it a long game. Maybe the new humans are smart enough to figure it out after seeing a larger piece in an (old) crater, which has happened many times close or on populated areas by now. Eventually it will be seen by this society as well, and possibly a larger piece normally visible in the sky (by telescope) has vanished.

The piece could be large enough to preserve much more as well, like logos or more intricate parts that are inside. They do not need to survive the crash, but simply be recognisable as crafted. After that it is a possible leap to 'destroyed megastructure in space'.

$\endgroup$
1
  • $\begingroup$ sorry for the comment-and-delete, I realized right after commenting that I had basically commented a distinct answer, but you must have been replying already. $\endgroup$
    – g s
    Commented Jun 21 at 17:20
10
$\begingroup$

No. They might see geostationary satellites but they would not see any detail on them. Here's some quick figures...

I happened to be re-reading Patrick O'Brian's "The Mauritius Command" yesterday, and I remembered Jack Aubrey boasting of being able to resolve a double star with a separation of a second of arc with his telescope. I have ground my own optics by hand, and know how ambitious this is, but Jack Aubrey has guidance from Caroline Herschel. Okay, this is fiction, but a bit of background search suggests to me that a resolution a second of arc was pretty much state of the art for about 1800.

The ISS orbits at about 400 Km. Without propulsion, its orbit would decay. Any debris original in LEO would have fallen to Earth some while ago. So let us take 400 Km as the lower limit of the range of the object when looking straight up. A resolution of one second of arc would be 400 Km / 60x60x60 = 400/216 m, or about 2 meters. You would probably not be able to read "USA" at the bottom of a Saturn 5 booster.

There is another problem other than resolution: the ISS goes around the Earth in 90 minutes. If you want to catch the outline of the ISS against the Moon, then you are going to need a very fast exposure and some precision timing. If you looked at the stars with an 1800's telescope, you might see a bright light zip by if you were amazingly lucky.

Suppose we looked at debris is in geostationary orbit at about 36,000 Km. That would be a stable orbit, and you will not have to move the telescope to track that. However, your resolution is now 36,000 Km / 60x60x60 = 160 m. This is more than the height of the Saturn 5.

The 'zodiacal light' would have been known for centuries. This is the light scattered by interplanetary dust, viewable before dawn and after dusk given the right conditions. An astronomer of the age might expect any astronomical body to be orbited by moons, dust belts, and everything between. Maybe a careful observer might find satellites in geostationary orbit, and wonder how they came to be there.

PS:

There is a problem with viewing geostationary satellites. It is unlikely that the telescope would have an equatorial mounting and drive. Most of the bigger telescopes were transit telescopes: they traversed in altitude, and the azimuth was fixed at 90 degrees. Observers waited for the stars to come into view with the Earth's rotation. This fixed the position of the stars accurately enough for the first measurements of stellar parallax. But if you looked at stars like this, the geostationary satellites would not appear to move, so you would only spot them if there was a bright one on the axis of the telescope.

Anyway, this is a side-issue: the wreck of a megastructure would not be in geostationary orbit.

$\endgroup$
5
  • $\begingroup$ It's kind of hard to see the ISS with a telescope, yes... but it's also visible to the naked eye. Of course, that doesn't give you enough detail to make it obvious it's a man-made station, but it's more than enough to realize that it's a very suspicious thing in orbit. Granted, higher orbits make this much harder. And there's a good chance these observations would be compounded by the relatively frequent rain of debris (we're talking about an orbital megastructure, after all), assuming the civilization in question is near enough to the equator (where the megastructure presumably was). $\endgroup$
    – Luaan
    Commented Jun 24 at 7:04
  • $\begingroup$ @Luaan Thomas Jefferson said in 1808 on meteorites "I would sooner believe that two Yankee professors would lie than that stones would fall from heaven!". What seems obvious to us may not seem obvious to them. A megastructure, smashed to bits by the Kessler syndrome, would probably not show any lumps as large as the ISS, or in as low an orbit to make them visible. Much of it would have fallen to Earth in ancient times. Some people would say lumps of stuff fall from the sky. Others would not believe them. $\endgroup$ Commented Jun 24 at 8:46
  • $\begingroup$ Sure, but that goes back to how common the impacts would be; meteorite impacts were recorded for thousands of years, but they were very rare. One of the things that made the scientific community really accept the idea was the 1803 "meteorite rain" in France. It's easy to ignore the evidence when you get barely any reliable accounts within decades. But if there's anything of a megastructure left to observe in orbit, impacts of the debris should still be quite frequent - and unlike natural meteors, looking a lot more obviously artificial (even if highly damaged). $\endgroup$
    – Luaan
    Commented Jun 24 at 9:42
  • $\begingroup$ And of course, for bonus points, there was still that huge rift between "Continental" and "American" geology back in Jefferson's time; the Americans generally summarily dismissed any suggestion that catastrophic events shape the Earth. Which is why the idea of plate tectonics wasn't accepted in the US for decades after it became mainstream in continental Europe (and somewhat later in the UK). Again, with the amount of evidence being even more telling, it should be much easier to get to the right idea (while possibly delaying the understanding of natural meteors, of course). $\endgroup$
    – Luaan
    Commented Jun 24 at 9:49
  • $\begingroup$ Mind, all that still adds up to "pretty unlikely to observe reasonably", but also very far from impossible, which works fine for a story, especially if you want to make the research itself part of the story :P $\endgroup$
    – Luaan
    Commented Jun 24 at 9:52
6
$\begingroup$

No. Take a look through youtube at some amateur astronomers' attempts to picture the international space station. They're sort of recognizable, but even the good ones are fuzzy and indistinct. Then consider that the ISS is much closer than any orbit that would be stable for thousands of years... and that modern amateur astronomers have access to tools much, much better than the best telescopes in the world in the early 19th century... and that any recognizably artificial shapes will have been smashed up by thousands of years of collisions.

However, no telescope is required. Pieces of the debris will decay out of orbit for as long as there's a planetary ring worth looking at. I do not agree with Trioxidane's suggestion that some pieces will land intact. However, many pieces will be large enough that they don't completely burn up in the atmosphere, just like in real life with natural meteorites, and this is all that is needed. The iron and carbon meteorites can be explained away with natural causes, but there are no plausible natural sources for aluminum or titanium meteorites.

Since anyone who knows her post-apocalyptic Newton knows that the ring is the main origin of meteorites, it follows that the ring is artificial.

$\endgroup$
7
  • 2
    $\begingroup$ And yet a colleague of mine has taken spectacular pictures of the ISS in front of the moon. It is clearly the ISS, and clearly man-made. This with current amateur level equipment, so likely better, faster camera in particular, along with well known orbital parameters to get the timing down. $\endgroup$
    – Jon Custer
    Commented Jun 21 at 14:37
  • $\begingroup$ @JonCuster I have seen such pictures. The resolution is probably of the order of 1m, and so perhaps twice as good as I predict for an object in a 400 Km orbit. The telescope probably has a sensor at the focus instead of an eyepiece. It must have a fast shutter time, as the ISS crosses the moon in half a second. This is easy now, using easily available parts, but all this was impossible when I was young. $\endgroup$ Commented Jun 21 at 18:47
  • $\begingroup$ @RichardKirk - indeed, the big difference is a nice CCD sensor with a fast shutter, well timed. Eyeballing it is going to get a blur of something zipping by. $\endgroup$
    – Jon Custer
    Commented Jun 21 at 18:51
  • $\begingroup$ the ISS is moving very fast acroos the line of sight, otherwis imaging would be much easier. $\endgroup$
    – John
    Commented Jun 21 at 22:17
  • 2
    $\begingroup$ @RichardKirk, cameras have been able to take pictures of satellites transiting the Moon since about the mid-1880s -- the Moon is a brightly-lit object, comparable to an asphalt road in broad daylight. The hard part was working out the timing to know where to point the telescope and when: computing orbits by hand is much harder than doing so with a modern computer. $\endgroup$
    – Mark
    Commented Jun 21 at 22:51
4
$\begingroup$

Of Course!


It's a megastructure! How can anyone miss large numbers of hundred km wide, partially finished NASA QuBEs still attached to their two thousand by one thousand km gantry structures? Not to mention all the hundreds of structures and art installations on the Moon!


Even the most technologically deprived neohumans can still see the huge Coca PepsiCo and McPizzaKing ads, sponsoring MoonShow 3500! Whatever the heck that was ten thousand years ago!

$\endgroup$
7
  • $\begingroup$ A megastructure does not necessarily imply one big structure. A dyson swarm, for instance, is a megastructure, though it's comprised of many parts that do not have to be particularly large. I think that's what's being implied here - especially since it's talked about as being little more than debris at the time in question. $\endgroup$ Commented Jun 22 at 13:46
  • $\begingroup$ It is a destroyed megastructure that was in orbit for a long time. As per the question, it resulted in an orbital debris field. Though my answer relies heavily on larger pieces surviving, a 100km piece is very unlikely. This is a definite Kessler Syndrome scenario, where pieces fly out and destroy other pieces, and so on. Any 100km piece should not survive. Even if it did, too many would leave Earth orbit by either entering the atmosphere or flying into space. It is close to impossible for an observable piece to survive and stay in orbit that long. $\endgroup$
    – Trioxidane
    Commented Jun 22 at 18:17
  • $\begingroup$ OP uses the phrase "an orbital ring or something." That sounds enormous, even if the toroidal cross-section is 'only' several square feet. $\endgroup$
    – Tom
    Commented Jun 22 at 19:07
  • $\begingroup$ Reminds me of "The Man Who Sold The Moon" by Heinlein. +1 Alas, a well-shattered mega-structure will probably trash a lot of the surface of the moon as well. Worst case, the moon itself might be shattered. And that's assuming it wasn't already disassembled! $\endgroup$
    – David G.
    Commented Jun 23 at 2:07
  • $\begingroup$ @DavidG. Shattering the Moon is far outside humanity's league. Any civilisation that could do that wouldn't bother with megastructures, they'd simply move the Moon to a better orbit. $\endgroup$
    – toolforger
    Commented Jun 23 at 15:59
0
$\begingroup$

I love these speculative questions on if X is possible with Y technology considering Z constraint or capability on top but they are very hard to answer. Consider the following two questions. Did humanity have the technology to put people on the moon in 1962? Did humanity have the technology to put people on the moon in 1969? We did have the technology to send people to the moon in 1969 because it happened. That technology didn't exist just a few years prior but it was developed very quickly once people had the motivation and resources to develop those technologies.

When technology is moving quickly it is difficult to answer questions on what is possible at a given time. Once someone finds resources to create some new technological capability that means technology is going to develop even more quickly and because time keeps marching on it means at some point the 1800s turn into the 1900s, and 1962 turns into 1969.

Consider that telescopes existed since the 1600s and people have been using them for astronomical observation since. To pick out artificial satellites in a stable orbit would then just mean building a telescope large enough and precise enough to pick out something on the scale of perhaps a few meters that is in orbit potentially tens of thousands of kilometers away.

If we assume a level of scientific knowledge to that of 1850 or so then they understood how to make very nice telescopes for a couple hundred years by now, what was needed was to make one really big and stable. There was technology to make some very precise mechanical devices by 1850, and some of that technology in clockworks, mechanical computation, and measurement would have also been known for potentially hundreds of years at this point.

What was perhaps the "big leap" needed to do precise astronomical observations was photographic technology. With film photography people could make precise comparisons on what was visible from one time to another. If people on Earth are going to pick out objects in orbit then they'd need to see how things moved in the sky to then calculate that they were close enough to be in orbit around Earth than the sun or moon, but also know the objects they observe are far enough away that it's not something in flight like a bird or insect.

The technology for photography (and pardon the pun) developed very quickly. Photography was mostly theory by 1830 and then durable full color by 1870. If we are putting the level of technology at that of the USA in about 1850 then there was all the pieces there to build a large telescope that was capable of making high fidelity monochrome photographs of the night sky. I believe if given enough resources in materials and manpower that they'd be able to identify objects in orbit as artificial. Or that's at least my interpretation of history.

A question that comes to my mind is, how much material and manpower would have to be set aside for such a project? What kind of a society would have the excess resources to dedicate to something that is of such purely scientific interest? Looking up into the night sky isn't like developing rockets to the moon since rockets have commercial and military applications. Is there something motivating people to investigate these objects in orbit that they believe vital to their safety such as defense against an adversarial nation, or so fundamental to survival as the ability to produce food?

The fundamental technology and science, as well as industrial capacity, likely existed to put people on the moon perhaps 50 years before humans actually landed on the moon. A couple critical technologies didn't exist in the 1910s, the transistor and the radio-isotope battery. Maybe vacuum tubes and chemical batteries would have been sufficient if only they cranked up the power on the rockets a bit and accepted greater physical discomfort in their travels.

$\endgroup$

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .