Would a spaceport on Ceres make sense?

Question

I'm writing a setting where humanity is colonizing the Solar System, and I'm wondering whether a Entrepot on Ceres, a la The Expanse would make sense? For context, most of the human population still lives in the Earth-Luna system.

The rationale for colonizing Ceres was because of the increasing depletion of the ice craters on the Moon, such as Shackleton Crater. What I'm wondering is whether it would even make sense to have Ceres as a major trading hub, since the destination of most of the imports coming from the Belt and Outer System will be headed for Earth-Luna.

On Earth, trading hubs are viable because ships will go past them, and only have to slightly change their course to reach them, it doesn't cost them much. And they have to keep their engines running in order to move, and so they have to pick up fuel mid-course if they don't have enough to reach their destination.

But in space, ships will have to expend a lot of delta-v to divert their course to a port on Ceres, and even more to match speeds with the asteroid. Ships can just coast across the Solar System all the way to their destination without needing to stop and refuel. And it is not closer to the asteroids in the Belt at all times, since the asteroids' positions change relative to each other all the time, and can often be closer to Earth or Mars than Ceres much of the time.

Would a trading port on Ceres make sense, with ships from across the system stopping there on their way to deliver cargo to/from Earth-Luna? Or would it just be more logical to set up mining/refining operations there and ship the propellant straight to Earth-Luna, along with the rest of the exports?

Thanks!

Answer 1

It depends what services Ceres provides

From a time-and-delta-v point of view, it never makes sense to stop along the way in space travel. (It may, rarely, make sense to divert past a massive body to perform a gravitational slingshot, but Ceres is not massive enough for this.) However, there may be other reasons to use Ceres as a transport hub, though these reasons only make sense for bodies relatively close to Ceres - if Ceres is the only transpor hub then only the asteroids near Ceres at any given time are being exploited.

1. Further refining of materials may be possible. If substances have been refined in a semi-refined form but Ceres can refine them further to reduce the amount of "waste" mass being transported, it may be more economical.
2. Stockpiling may be desirable. Especially combined with further refining, it may make sense to stockpile goods on Ceres until it has moved into a more favourable orbital transport window. For example, if the trip to Earth from the current location would take 300 days but waiting 100 days will reduce the trip to 220 days, it may be worth taking the 100 days to mine another nearby asteroid, get it all refined and then leave for Earth with a double-value load.
3. Alternative shipping. Ceres may have a mass driver for flinging loads into a near-Earth orbit. There are financial advantages to keeping the mining ships with their specialised mining gear operating on asteroids in the vicinity rather than using an expensive piece of mining equipment as a bulk transport. There are alternatives that do not require a transport hub - for example, mining ships could keep mining and send their payloads back to Earth using a stock of unmanned solar-sail drones - but if you want Ceres to be a transport hub then stick a mass driver on it.
4. Low-G R&R and maintenance. As with the previous point, the longer a mining ship is not mining the less profitable it is. If sufficient facilities for maintenance and recreation are available on Ceres and it takes much less time to reach Ceres compared to Earth-Luna, then the mining companies would probably prefer to have their ships offline for a few weeks travelling to/from and spending time at Ceres rather than months travelling to/from Earth-Luna.

Answer 2

(Note: this is a relatively 'hard science' answer, and I'm assuming no clarketech drives. So delta-v requirements and travel times are appropriate for chemical rockets and I'm assuming the main use of ice is to make fuel.)

For the outer Solar system: No

For a spacecraft coming from or going the outer Solar system, possibly laden with goods, it's absolutely never going to make sense to come to a stop at Ceres instead of coasting past it. Sure, you can pick up some fuel there, but you'll burn a huge amount of fuel bringing the whole ship to a stop and starting it up again (not to mention inclination changes and so on), so this isn't going to be economical.

Instead of stopping the ship, it might make more sense to accelerate the fuel, since this takes less delta-v. So you could end up with a bunch of ultra lightweight fuel carrier ships accelerating out from Ceres to rendezvous with heavier ships en route, instead of ships stopping to rendezvous with the fuel. But keep in mind that ice is abundant in the outer Solar system, so it seems more likely that people would just make fuel in the outer Solar system, then bring it back to Earth and sell it in Earth/Moon orbit for others to use on the outward trip. This scheme wouldn't involve Ceres at all.

For the asteroid belt: Yes

The thing about the asteroid belt is that most things are in similar orbits, so getting from one asteroid to another takes essentially no energy, as long as you're not in a hurry. The asteroids are all very close to each other, if you think in terms of delta-v rather than distance or time.

If you're on the other side of the Sun it could take years to get to another asteroid, but at any given time there will be plenty of asteroids that are within, say, a week or so from Ceres orbit with minimal delta-v expenditure. So if there is a big hub on Ceres, or anywhere else, then for a lot of people there will be no good reason not to stop off there to pick up fuel and food, trade within the belt, etc., before making the long journey to Earth. It seems quite natural that such a thing would develop, and Ceres is as good a place as any.

Note that while water is somewhat scarce in the asteroid belt, it is present in plenty of places besides Ceres, including a lot on Vesta - see Wikipedia's asteroidal water page. So the presence of water wouldn't necessarily be the main reason. But Ceres is big and has solid ground to build on (albeit without much gravity), so it would probably make sense to build stuff there, such as fuel processing factories, trading facilities, farms etc. It would be similar to the way cities sometimes develop, where a small settlement grows due to the volume of trade flowing through it, rather than due to special resources that are only found there. Because not every asteroid is near Ceres at any given time I would expect there to be other hubs as well, but there's no reason Ceres couldn't be the biggest one.

Answer 3

Entertainment:

In addition to Kerr Avon's answer, I'd propose that the since Earth and Ceres only line-up in the solar system on the same site of the sun every 4 years and 6 months (and a couple of weeks), and the rest of the planets and other useful bodies in the solar system are constantly in-flux - your port will need entertainment facilities, hotels and possibly hibernation/suspended-animation facilities.

If the colony supporting the port-facility has a certain degree of autonomy:

No doubt there'd be official rules about what's allowed there, security would see that the rules are obeyed - but, for a price, for the right cargo if a rich ore-vein has been mined or a trade-deal has been struck, then people really want to celebrate. What better place for an "underground" pleasure facility offering all those things that other colonies (with families/children/security services etc.) cannot offer. This only needs hinting at in the writing as the readers' imagination will fill in a lot of the rest,

Answer 4

Yes

There will be a strong incentive for growth to occur as expansion of existing footprints, rather than setting up new habitats. That's because any movement at the scale of the solar system will come with a very high price tag, in terms of delta-V and time; there is no such thing as a "nearby" location: everything is located either "here" or "very far."

Ceres is a very natural base for asteroid mining. But I would expect there to be multiple habitats of the same size spread out at intervals around the asteroid belt. The base at Ceres might be built first, or built bigger, but it won't be the only one at that distance from the sun.

Probably the most important reason to have bases there is as supply depots: every vessel needs fuel and atmosphere, and there are a million ways a vessel can spring a leak during its adventures, venting more O₂ than they can afford to lose. Having more big stockpiles of that stuff spread out around the system will be a vital part of minimizing the likelihood of party-wipes (so to speak). That's the other thing about space travel, there are generally only two outcomes: it goes fine, or everybody dies.

Do note, however, that these stockpiles won't be much use in serious emergencies, like the kind we see in action movies. Most mishaps will occur days or weeks away from the nearest base. So, the benefit is not that a rescue team from Ceres will rush to your aid in a sudden crisis, it's that if you can limp to the nearest Ceres, they will probably be able to refill your tanks enough for you to make it home rather than asphyxiating or having no fuel to brake at your destination.

Answer 5

Not so much.

Consider that, while the planets with the closest orbit to Earth are Mars and Venus, the planet which is actually closest to Earth on average is Mercury, because of its orbit, which brings it more often closer to Earth.

Ceres would be, on average, far away from any other destination in the solar system, which is terrible for a port. Something like going from Los Angeles to San Francisco through New York.

To be clear, I am not suggesting Mercury as better location, just giving it as an example on the need of considering the average distance, not just the distance between orbits.

Answer 6

The main reason most ports exist is NOT practical, but for the purposes of taxation, Customs Control and trade regulation. If not for those things, we would instead have 1000x more tiny ports closer to land routes, instead of giant port cities.

Simply put, the Spacers would want Ceres to be their main port-hub, which in turn would directly deal with Earth-Luna, financially, and politically.

Yes, if you have an asteroid-mining ship, it makes more purely practical sense to ship ore directly to a Lunar Port instead of Ceres; except when you dock, the Lunar-Terran Trade Agency slaps you with 120% ore tax.

Instead, you ship it to Ceres, accept Ceresian Customs Fees (which are reasonable, because the last Ceres Port Admin who wanted to raise them were sent to explore the vacuum of space without an EVA suit). Then have Ceres deal with the greedy Terrans.

Remember, the greatest force in the Solar System, greater than Gravity, Momentum, Inertia or your Nuclear Engines, is HUMAN GREED, especially one enhanced with soulless, ham-fisted bureaucracy.