If you’re anything like me, you might have enhanced your friends’ enjoyment of space adventure films by pointing out at great length and in fascinating detail just why the crowded asteroid belts backgrounds that appear in so many of these films are implausible and inaccurate! Our solar system asteroids are far from crowded. If you were to find yourself on the surface of a typical asteroid, you probably wouldn’t be able to see your closest rocky neighbour with a naked eye.1
Are there situations in which these visuals wouldn’t be misleading? Can we imagine places where we could expect what appears to be an impending Kessler Syndrome on a solar scale?
At first glance Jupiter’s trojan asteroids look like they might do. For reasons gravitational, Jupiter has collected two impressive sets of asteroids in its L4 (leading) and L5 (trailing) Lagrangian points. Between them, the two populations of asteroids (one named—mostly—for Trojans, and the other named—mostly—for Greeks [even-handed treatment of both sides of the Trojan War]) may number almost half a million 2 km+ diameter asteroids, over a million 1 km+ objects, and a larger number of smaller bodies. A cloud in a limited area with millions of bodies in it sounds very promising indeed!
Unfortunately, the term “point” is somewhat misleading. The L4 and L5 communities are spread out about 2.5 AU along the orbit of Jupiter. A quick back of the envelope calculation2 suggests that the separation between the 1 km rocks could be comparable to the Earth-Moon distance. This is excellent news for people hoping to found vast clouds of space habitats (not only are the rocks comparatively close but also the delta vee to get from one to another is low3) but less than excellent news for fans of crowded asteroid belts. A sky full of 1 km rocks separated by hundreds of thousands of kilometers is not the jam-packed vista beloved by skiffy fans.
(Obviously, for each 1 km object there are a number of smaller bodies but the decrease in average separation won’t result in angular width discernible to the human eye.4)
Somewhat farther from our sun, Saturn’s rings seem offer the very thing we want. The rings are composed of a very large number of bodies, most of them somewhere between marble and shed-sized (in total, massing about the same as a small moon). The close proximity of Saturn prevents them from aggregating into a single body; basic orbital mechanics constrains them to a surprisingly thin (10–10,000 metres) plane. If you were within the rings, your field of vision would be jam-packed with small bodies of appreciable angular diameter.
Unfortunately, their apparent size would be due to close proximity, so it’s probably a good thing most of the ring particles in a given region likely have more or less the same orbit. If that weren’t the case, the experience might be akin to having swimming pools full of gravel fired at you at supersonic speeds. As it is, maybe it’s more like being in a cement mixer filled with dice.
Moving above or below the ring plane will deny you the immediate effect of being surrounded by a myriad of objects, but replace it with a no doubt stunning vista of the rings seen from just above or just before, for as long as it takes your ring crossing orbit to pass through the rings. Bring armour or hope for low relative velocities while you traverse the rings on an orbit whose parameters are definitely different from ring particles.5
Another option is to find a very young stellar system, still rich in planetesimals, where giant worlds have not either absorbed them or thrown them out of the system. Not only would such a system have a more chaotic and more populous collection of small bodies, but proto-stars and very young stars offer all manner of potentially exciting behaviours not seen in boring, middle-aged suns like our own.
(This would seem to require a time machine or really good space ships. But perhaps all we need is patience enough to wait until the next time the solar system passes through a stellar nursery. A few million or billion years … no prob.)
Perhaps the easiest solution is to posit successful space industrialization combined with a lack of environmental regulation. Earth seems likely to be the main market for goods for the foreseeable future. Therefore, why not transport megatons of semi-processed raw materials to the Earth-Moon system for use in facilities in proximity to Earth? And wouldn’t compelling companies to take whatever steps are needed to prevent increasingly dense clouds of debris in said system be an onerous burden on hard-working business folk? With just a little effort, and a lot of short-sightedness, perhaps we could have entertainingly crowded skies in our own back yard. (And eventually a Kessler syndrome that would provide a one-time spectacular light show for those of us fortunate to live on the planet surface.)
In the words of Wikipedia editor TexasAndroid, prolific book reviewer and perennial Darwin Award nominee James Davis Nicoll is of “questionable notability.” His work has appeared in Publishers Weekly and Romantic Times as well as on his own websites, James Nicoll Reviews and Young People Read Old SFF(where he is assisted by editor Karen Lofstrom and web person Adrienne L. Travis). He is a four-time finalist for the Best Fan Writer Hugo Award and is surprisingly flammable.
[1]Assuming one’s space helmet neither assisted nor impeded vision. Obviously, if one simply doffed the helmet, the optical properties of the face plate would no longer be an issue, although painful death by vacuum that would immediately follow could be very distracting.
[2]Carried out for me by a friend because, for reasons related to my CPAP machine, my brain is befogged. This is why an early draft of this essay had three footnote 1s.
[3]The delta vee to send material to and from Earth isn’t horrible if you’re willing to invest the years to send the packages via Jupiter. The nice thing about using Jupiter as a central shipping point is that the scale of the system is such nobody is going to get a large spaceship jammed in a crucial shipping lane.
[4]Why not simply replace the human eye with something with more resolving power? This sounds reasonable but it turns out that while removing eyes is one ice-cream scoop away, actually replacing them with something functional, let alone superior (whatever parameters you are using for superior) is a bit tricky.
[5]Traditionally, people exploiting the rings do so for the abundant water. Alas, the same proximity to Saturn that keeps the rings from collapsing into a moon mean the delta vee cost of retrieving material from the main rings is not insignificant. Water is abundant in the outer solar system and there are places from which one can retrieve it at lower cost. A suggestion I ran across more than a decade ago is that a very small fraction of stranglets (https://en.wikipedia.org/wiki/Strangelet) passing through Saturn could be braked just enough for ring material to finish the job. Stranglets could have many interesting applications, and probably could not be used to destroy the world. (Note: it would be scientifically timid not to test that last assertion.)
” The L4 and L5 communities are spread out about 2.5 AU along the orbit of Jupiter. A quick back of the envelope calculation suggests that the separation between the 1 km rocks could be comparable to the Earth-Moon distance. This is excellent news for people hoping to found vast clouds of space habitats (not only are the rocks comparatively close but also the delta vee to get from one to another is low)…”
That is good to know. My Troubleshooter series (the novel Only Superhuman and several stories) is set in a future where the Main Asteroid Belt is widely settled and increasingly civilized, while the Trojans are the lawless frontier beyond it. This suggests that by a later generation, the Trojans may have even surpassed the Main Belt as a home for Strider civilization (my term for asteroid-dwellers, because I thought “Belter” was too derivative and dull).
“Another option is to find a very young stellar system, still rich in planetesimals, where giant worlds have not either absorbed them or thrown them out of the system.”
I doubt even that would achieve Empire Strikes Back levels of planetesimal density. I gather that protoplanetary disks around other stars can be hundreds or thousands of times denser than the Main Asteroid Belt, but when the typical separation between asteroids in the Main Belt is something like 16 times the Earth-Moon distance, increasing the density by a factor of a thousand would only reduce that to 1.6 times the Earth-Moon distance (I think), so on the order of magnitude of the Jupiter Trojans.
The only way you’d get something dense enough for Han Solo to elude TIE fighters in would be if a clump of planetesimals were already well on the way to condensing into a protoplanet, and that’s going to be very ephemeral on a cosmic scale, so the odds of finding such a thing will be extremely low even if you have hyperdrive (which the Falcon didn’t, come to think of it, which was the whole reason it was in the asteroid field in the first place).
Alternatively, as briefly seen in the previous film, such a dense clump of debris could be left by the destruction of a planet by the Death Star. But that only happened the one time — that we know of. Could it be that the Empire asteroid field was actually the leftovers from an early test of the Death Star weapon? That could explain how there were life forms on some of the asteroids, if they were the remains of a formerly inhabited planet.
See also “Hostile Takeover” by Susan Shwartz, set among the mining colonies in the asteroid belt. It takes the unusual approach of being a corporate thriller, with the protagonist being a Company auditor sent out to investigate suspected financial irregularities in the local offices there. The book gets into not only the worldbuilding of such colonies, but the dynamics and structures of the kinds of corporations that would operate them.
IIRC, Heinlein hangs a lampshade on this nicely in “Farmer in the Sky”.
Dur. Now that it is too late, I should have mentioned that 120 million kilometre wide set of rings in the J1407 system.
@3, I immediately thought of Heinlein. The narrator of Farmer states that the older pile drive ships used to power through the asteroid belt but none took any hits worth talking about. The torch powered Mayflower, having literally all the power in the universe to spend rises above the orbital plane just to be extra safe but – ‘It must have been a Blue Moon, we were hit.’
In The Rolling Stones it’s noted that a ship could pass right through Rock City, an asteroid belt community, without seeing anything but points of light.
@5/roxana: I think the novel version of 2001: A Space Odyssey also has a discussion of how sparse the asteroid belt was. That’s probably my original source for the knowledge.
@1. Though the whole reason the Alliance was at Hoth was because it was such an obscure out-of-the-way system that they thought they’d be safe.They might well have deliberately sought out exactly such an “ephemeral” situation.
Characters note in dialogue that there’s a lot of asteroid/meteorite activity in the system (which tie-in writers have noted is another quality that makes for a good hiding place, making it easier to obscure/disguise starship traffic –and forcing any large cruisers to either take the long way in or immediately announce themselves to the whole system [the Alliance thanks you, Admiral Ozzel]). It might well have been a protoplanetary system caught in the thousand-year process of condensing.
I guess Seveneves was too much of a gimme…
In Tom Swift: The Alien Probe (1981, Victor Appleton (house name)), chapter 9, when embarking to Ceres there’s a three-page infodump (“my knowledge of the asteroid belt is limited … tell me about it” one character asks Tom) concluding with “even with a half million rocks out there, the orbit is so large that you probably couldn’t see very many from any one asteroid.”
In their exciting escape at the end of chapter 15, “[the ship] withheld ignition for two hundred nanoseconds until a chunk of rock the size of the Cheops pyramid cleared the path ahead” which … that’s more likely to be a satellite of Ceres than a passing neighbor, I guess? NASA doesn’t list any moons for Ceres, but the recent category of “dwarf and minor planets with moons” usually refers to things at least several kilometers in size. The NASA Dawn probe orbited Ceres from 2015 to 2018, but that’s not the right place to do a wide optical survey for tiny things.
@7/Cybersnark:
The presence of an ecosystem (including atmospheric oxygen) argues against a “young” star system, but there seems to be very little “natural” about Star Wars planetology. Maybe somebody had terraformed Hoth as a cold-weather safari location a few thousand years earlier, stocking it with species (wampa, tauntaun … and unseen autotrophs) from elsewhere. (If Jabba the Hutt can take up residence in a B’omarr monastery on Tatooine, the Rebel Alliance can refurbish an abandoned hunting lodge … except that makes for an obvious target.)
@5 Heinlein did a couple of other “takes” on the asteroid belt. In SPACE CADET, they’re on a mission to the asteroid belt to locate a missing exploration ship. When they find it, it turns out the crew is all dead, owing to a freak accident–when the airlock was open, a bit of debris flew in and smashed through the other hatch. It’s later revealed that the ship had found evidence that the asteroid belt was the remnants of a destroyed planet (that’s then named “Lucifer”), and that there was further evidence that it had been inhabited, and that the inhabitants had done it to themselves.
Later, in STRANGER IN A STRANGE LAND, it’s mentioned almost in passing that the Martians had been somehow concerned about the inhabitants of the “fifth planet” and had destroyed it, leaving the asteroid belt in its place.
We might set up in a comet in process of disintegration. Plenty of volatiles, plenty of surface area. Just make sure your database of objects stays up to date.
It’s about the first place I’d go if I were a Bracewell-Von Neumann probe.
@7/Cybersnark: “Though the whole reason the Alliance was at Hoth was because it was such an obscure out-of-the-way system that they thought they’d be safe.”
And yet at the same time it’s within at most a few days’ sublight travel distance from Bespin.
@11/Russell H: “Later, in STRANGER IN A STRANGE LAND, it’s mentioned almost in passing that the Martians had been somehow concerned about the inhabitants of the “fifth planet” and had destroyed it, leaving the asteroid belt in its place.”
Marvin did it. It was blocking his view of Jupiter.
Here’s a thought: A single large asteroid that’s recently been in a collision and shattered could work pretty well as a Hollywood-style spaceship obstacle course. There’d be a lot of small pieces relatively close together with a lot of kinetic energy. They’d occupy a small volume on a cosmic scale, but a significant volume relative to a spacecraft. It would again be a very ephemeral formation in the grand scheme of things, so it would be improbable to happen across one just at the right stage before it either re-coalesced or dissipated entirely. But collisions are relatively common in asteroid fields, so the odds of finding one would be commensurately increased.
@1, 14/CLB:
Later official written material resolved that apparent astrographic plot hole by giving the Falcon a backup, slower hyperdrive (see StackExchange discussion, Wookieepedia entry). Evidently it’s not a “hot” backup and hence not useful for evading Imperial pursuit, but something that has to be manually installed, rather like a spare tire. (“Offline spare” might not be the stock configuration, but it’s a reasonable consequence of the hot-rodded, jury-rigged nature of the Falcon.)
(If the Hoth-to-Bespin trip does take weeks, despite what the film’s editing implies, that provides necessary time for (a) Han and Leia’s romance to blossom, and (b) Luke to train with Yoda.)
@15/phillip: “(If the Hoth-to-Bespin trip does take weeks, despite what the film’s editing implies, that provides necessary time for (a) Han and Leia’s romance to blossom, and (b) Luke to train with Yoda.)”
That’s my preferred interpretation, although I’m not sure a hyperdrive is necessary for that. Hoth and Bespin could be around the two stars of a wide binary system, a few light-days apart, maybe. Hoth could still be considered fairly remote in that sense because it’s a long sublight trip from Bespin; it’d be the equivalent of something like Eris or Haumea in our outer system, so far from the populated planet that it might as well be in another system altogether.
Or in the sense of New Hamburg from Toronto: sure, the 401 will take you from the second to the first but that requires someone in Toronto to have heard of New Hamburg in the first place.
For reasons that escape me now, I thought in the 1980s that Star Wars would make more sense if it was set in a globular cluster where interstellar distances were much, much shorter than our neck of the woods.
@17/James: “I thought in the 1980s that Star Wars would make more sense if it was set in a globular cluster where interstellar distances were much, much shorter than our neck of the woods.”
It would make slightly more sense of Hosnian Prime’s destruction being visible from multiple other planets…
Bespin doesn’t exactly come across as being a major settlement–Cloud City is a mining outpost (one whose ownership is staked in a card game) and is the biggest concentration of people we see (I gather later material put another city there as well, but we don’t see it on screen).
The difference between Hoth and Bespin may be the difference between hiding in the middle of actual wilderness vs. hiding in a still-barely-populated mining town in the middle of the American Southwest.
@19/FourDs: On the contrary, Cloud City was a large, advanced, sophisticated city, not some backwater outpost like Mos Eisley. According to Wookieepedia, it had a population in the millions, and the top 50 levels were a popular luxury resort.
I think Lando had made some improvements.
@10: I have long thought the same thing about the planets of the Galaxy Far Far Away. Some of them are plausible natural systems, but then you have Hoth: Accidental Runaway Ice Age World (with megafauna presumably migrating between hot spots) and Naboo: Planet Aquarium (with humongofish). A lot of stuff about the GFFA makes more sense if you postulate godlike ancient aliens who gardened the galaxy before departing or dying or turning into apathetic starbabies or what have you.
“For reasons that escape me now, I thought in the 1980s that Star Wars would make more sense if it was set in a globular cluster where interstellar distances were much, much shorter than our neck of the woods.”
Congrats! You re-invented Firefly!
@22/Jenny Islander: I dunno — single-biome worlds aren’t as unlikely as Star Wars critics often insist. Snowball Earth was probably a thing more than once in prehistory, the entire planet almost completely frozen over, and there are tons of actual ice moons and dwarf planets in the outer system. Mars is essentially a single-biome desert world. And scientists theorize there are many ocean planets that are 100% covered in water with no land at all, like Kamino (although Naboo is as implausible as you say).
Although all those environments are basically barren (a pure ocean world with no land masses to erode minerals into the water would be pretty sterile). Where the single-biome idea becomes unlikely is with, well, actual biomes, environments for life. A world uniformly covered in, say, redwood forest is vanishingly unlikely, because life is too complex and dynamic to be as uniform as a barren environment.
Maybe the asteroid field in “The Empire Strikes Back” was really a flock or school or shoal of critters pretending to be rocks. Or wearing rock shells, like hermit crabs. Though if that’s a thing in that universe, would space travellers generally know about it, and not land on or in them?
Space whales are a long standing science fiction device. One of the 30th century Legion of Super-Heroes is named Jo Nah. Actually, I gather he was written in the 1960s, and “TV Tropes” doesn’t seem to have any space whale literature earlier than that, but I feel that the point stands.
ChristopherLBennett @@@@@ 24
Although all those environments are basically barren (a pure ocean world with no land masses to erode minerals into the water would be pretty sterile).
Hydrothermal vents? (Arguments about possible life on subsurface oceans on ice-covered worlds (e.g., Europa) — which are basically ocean worlds with a roof of ice — usually posit something like that as sources of both heat/energy and minerals.)
@26/Peter Erwin: The kind of ocean planet I’m talking about would have oceans thousands of kilometers deep, so that most of their depth would be special high-pressure ices, and any rocky core would be buried far, far below all that ice, with no interaction with the liquid water.
My novel Star Trek: Titan — Over a Torrent Sea featured such a planet and explored its ecosystem in depth, including a mechanism for how it maintained enough fertility for life. As far as I know, it was the first full-length science fiction novel to feature a Léger-type ocean planet as its setting, although Ian McDonald’s novella “The Tear” beat me to it by a year or so.
Hal Clement’s 2003 Noise is set on a deep, deep ocean world with no indigenous life.
@28/James David Nicoll: I actually drew on Clement’s Noise in writing Over a Torrent Sea; it helped me figure out the meteorology of a world with no land masses. However, Noise came out a month before the paper where Marc Kuchner and Alain Léger proposed their version of an Ocean Planet, one where half or more of the planet’s mass is water and the majority of it is in the form of high-pressure allotropic ices. Clement proposed a less extreme ocean planet with a relatively shallower ocean that’s liquid water most of the way down and supercritical (on the cusp between water and steam) where it abuts the molten core, hence the constant noise of the title.
I totally forgot about this animation or I would have included it.
There are a number of older SF novels that involve the asteroids having once been a planet; I remember Nourse’s Scavengers in Space as not having the gross defects of Raiders from the Rings and having as its MacGuffin a picture of the planet breaking up. Kepler has as much to answer for as Schiaparelli.
Thanks for this discussion, lots of interesting ideas here!
I haven’t read Farmer in the Sky since it came out. Maybe it’s time for another look. (I reread Door into Summer maybe 15 years ago, with I think at least as much enjoyment as the first time, and quite possibly more. Possibly my favorite of his novels but then my memory of many of them is quite hazy.)
I don’t vociferously complain about asteroid belts but they do bother me more than explosions in space or more or less anything else the movies feel they need to do. Time travel through black holes is fine with me (or the sudden appearance of witches, for that matter) if you want to build a plot around it. But this asteroid business is in some sort of uncanny valley.
It seems Fomalhaut has an even more impressive set of asteroid belts than previously suspected.
“Mars is essentially a single-biome desert world”
A) Mars, unless I have missed something pretty huge in recent headlines, is a zero-biome world
and
B) There’s a lot of variation between the equator (plus 5 degrees) and the poles (cold enough for carbon dioxide to freeze)
@35/Ajay: First off, yes, I already acknowledged the imperfection in the use of the term “single-biome” in that context in comment #24 when I said “Where the single-biome idea becomes unlikely is with, well, actual biomes, environments for life.”
Second, “desert” means an environment with little or no liquid water, regardless of its temperature. There are hot deserts and cold deserts. Most of Antarctica is considered a polar desert. The point is that it is not implausible for a planet to consist almost entirely of desert climates, because different planets have different amounts of water.
ChristopherLBennett @@@@@ 36
Ajay is correct. Biomes are defined in terms of communities of organisms. No biological organisms, no “biomes”. Saying Mars is a “single-biome” world is like saying it’s a “single-ocean” world.
Also, the “climate” of Antarctica is rather different from the “climate” of the Sahara.
(I agree that since evolution is a thing, it’s very unlikely that — given the presence of life — you could ever have a “single-biome” planet.)
@37/PeterErwin: Again: I already acknowledged my own inaccurate use of “single-biome” in my original comment.
“Also, the “climate” of Antarctica is rather different from the “climate” of the Sahara.”
But they are both desert climates, which was my point. It is no more implausible to have a planet that’s entirely desert than it is to have a planet that’s entirely ocean, because it’s simply a matter of how much water the planet has.
Speaking of rings around gas giants: I always found the opening sequence of Star Trek Voyager hilarious. How big would the ship have to be to create that image, not to speak of it even having a reflection on the rings…
@39/Chaironea: “How big would the ship have to be to create that image”
About as big as the TOS Enterprise would have to be relative to a planet in order for its orbital path to curve visibly on the scale shown.
“not to speak of it even having a reflection on the rings…”
Worse, it isn’t even a reflection of the actual ship, but of a rough stand-in CGI model, since the ring animation was created and rendered before the ship design was finalized.