Exploration of space

A current topic if any. I had some thoughts recently about how hard it might be, even with FTL travel to explore even small regions of space.

A hypothetical setting: a way to travel faster than light has been discovered and a stable jumpdrive-ship built. The maximum speed it can travel is roughly 1 ly / day, vastly more than the speed of light. The drive can be activated in the outer solar system, to where it takes a week or two to travel with the sublight drives.

The practical range of travels with the ship is limited to two months, after which it starts running out of food, air and fuel. 6 weeks of travel is roughly 95% safe not accounting accidents or unforeseen problems.

So around 42-56 lightyears is the maximum range of the ship. The ship can, when entering a system, survey the entire star system in a 1-3 days, depending on the system, with an average of 1,5 days.

It would be logical for the ship, being still first of it's kind, to first make short jumps to nearby systems: Proxima Centauri, Alpha Centauri, Sirius, etc. First to the Centauri system and back, a 9-10 days trip in total. Then a two-system journey, say to Sirius and then Lalande 21185. Sirius is 9 days of hard travel, then about 5-6 days to Lalande 21185 and finally back home, another 8 days. In total, the journey took 21-22 days plus a few days to survey the system.

Now the ship has spent around 5 weeks exploring and has reached 3 systems. A still longer journey is planned out: going by Barnard's Star and Ross 154 to HD 217987. Barnard's star is a little over 5 light years, getting there is 6 days. From there, Ross 154 is about the same distance, 6 days more. Then, to HD 217987, roughly 9 more days. And let us say 6 days of surveying. The total time of this star trek has been 27 days, almost a month. The ship can still travel a little less than doubly this travel, we are approaching the limit. The ship has now seen 6 systems during it's journeys and systems close to Earth are running out. And a roughly two-day survey on each system gives only a slight clue on the planets and their possible habitability. And the usefulness of each system can only be guessed at the moment. But that is not the concern of this exploration vessel.

Now an even longer trek, off first to UV Ceti, Epsilon Eridani, then Wolf 359, then Ross 128 and finally to DEN 0255-4700. The travel takes 9 days to UV Ceti, from there about 7 days to Eplison Eridani, then almost two weeks to Wolf 359, then say a 5 day travel to Ross 128 and finally a 12 day travel to DEN 0255-4700 and 17 days home. The total travel, including the surveys take about 70 days. The ship will be almost running on fumes and the crew a bit tired when they return. And now there has been almost 4 months of exploring. Not so much as such, but so far the ship has explored 11 systems out of the 50 systems within 15 light years from Sol. With the rate remaining the same, within one year there would be around 30-35 exlored systems, within 20 months all of the nearby systems would be explored. But of course the rate would drop and I'd assume that the real time spent to explore all the 50 systems would be somewhere around 2-2½ years. Possibly 3.

Now humanity has explored a roughly spherical volume of space, 15 light years in diameter. The local bubble, the next step, is 300 ly across. With a spherical volume, it would be around 94247 cubic ly. This area might contain somewhere around 10 000 solar systems and assuming rate remaining constant (it wouldn't), it would take around 300 years to explore. After this step, humanity has explored around 1/100th of the distance from the Sun to the Galactic Core.

Of course, while time progresses, there would be more exploration ships, the technology would improve and people would start building colonies and starbases further away from the Solar system. And starships could be away longer periods of time, perhaps even a few years, exploring.

Still, exploring a galaxy might take time. And of course there might be prioritizing. If the priority is in establishing new colonies, surveys might only be done to systems likely to have habitable planets. This would quicken up the exploration a great deal, but a huge portion of stars would be left unobserved.

Sublight Travel

This one has bothered me for a while in my game setting and some others as well so I'll write up my thoughts here and try to sort it out.

So, let us assume that there is a way of working FTL which works with speeds of about 0,3-0,5 parseks an hour. It's drawback is that it doesn't work well in a gravity well. Previously I had specified that the limit a ship could approach an object in space was about 100 times the diameter of the object multiplied with it's surface gravity (a cheap ripoff from Traveller, I know). With average settled planets in this setting this would be about a million km.

Now then, concerning gravity wells, the largest in a solar system would naturally be the star(s). With our dear Sol this would be about a million kilometers, making it's base jump limit around 100 million kilometers, just short of Earth. However, when multiplied with the surface gravity of 27g this would create an almost 2,7 billion kilometer no-jump zone, about 18 AU, roughly around the orbit of Uranus.

Now, this makes interstellar travel a bit more slow. While it takes a few hours to make the jump from, say Alpha Centauri to Sol, it still would take quite a while to make the travel from Uranus to Earth on sublight. At light speed it would still make about two and a half hours to reach it.

Until now I've ignored the effect of the Sun in this, limiting myself only to planetary gravity wells but after doing a little study for another project of mine I realized that I cannot do this without proper explanation. It's paradoxical, isn't it? Why take some wells into account and not others? Are stars somehow different than planets, would this be a question of, say, densities? Star densities are way less than planetary densities, even Saturn is more dense than the Sun. It would make a more simple explanation to include the Sun gravity well into the accounts as well.

So, let us now consider the two models of gravity well jump limits with the stl technology available. Previously, starships were doing about 2-3 g tops, most ships around 0,5-1g. Courier ships and such might break for 8-10g but that would be it. That would mean that a 1g acceleration ship would accelerate to around 9,8 m/s squared. Let us say that fuel limits cap this acceleration to a delta-vee of 30 km/s. Travel from Uranus to Earth would take almost three years. Not really viable as I thought that the absolute travel time to a world 10 pc away would take about a day. Outer system colonies and stations would boom as trade hubs though, as merchant ships would want to minimize the travel time and just dump the cargo, get paid and leave. And faster in-system ships would then take the trade items further in-system.

Now then, ignoring the effect of the sun, a starship would appear around 1 million km from Earth. With 1g acceleration and a 30km/s delta-vee the ship would take about 9 h 15 min not including deceleration to reach Earth. A bit long still but more viable. In Earth's case, having stations in lunar orbit would be profitable since ships would then prefer to dock at the much nearer moon stations, leave the cargo there to the middle man and leave.

However, I thought a different solution. Increase the acceleration so that ships in-system would travel at around 0,1-0,3c. The solution I thought of is gravity drives which would be almost like warp drives in themselves. This would still make the travel from Uranus to Earth a long travel, around 12,5 hours on the average 0,2c speed, not including deceleration. With gravity compensators onboard (a technological item already included in the setting), inside the ship people would not notice the acceleration much. Which is good, since the planned 50-200g acceleration would squash a crew in an instant to tomato juice. I've planned that the grav drive would take it's power from fusion reactors onboard. This would however make smaller fighters less effective because of the space reactors require. Smaller ships would be mainly for maintenance, supply runs and crew transfer. On the other hand, ships built for battle would be huge.

This creates another problem. I've always liked the setting's emphasis on heroic fighter pilots fighting amongst large battleships and swarming the bigger ships with missiles. Emphasizing bigger ships would however make rebellions a much harder thing to do without orbital support and when the Imperial Navy kicks in, it's over. Then again, even a well-equipped fighter squadron defending a world would be doomed since the Imperial Navy has it's own fighter squadrons to deflect such attacks. And of course clever tactics will always be an advantage.

The appeal of having a large system to travel through before arriving at the inner system inhabited planets is largely of the chances of action along the way. While the journey of a million kilometers to a jump point might include some exitement, fast ships could intercept the pirate attacking around the jump limit and it is a little risky running that close to the planetary security. Not profitable. With a couple of light-hours to travel there might be "accidents" and the patrol is far away..

I'll have to think and see where this goes.

Colonies, space

I covered previously colonies on the surfaces of other planetary objects. With this article, I will cover asteroid colonies and colonies in space.

Space and asteroid colonies have several advantages over planetary colonies. They can be (although slowly) moved, they can be expanded and they have plenty of energy coming from the sun. Depending on it's location it can be a center for manifacturing, processing, commerce or military. The versatility and adaptability of the space colony makes it a strong option. Also, space colonies are seldom very heavily populated (let us say seldom more than 1 million) and are probably shielded so that upon a catastrophic event the colony can be easily evacuated at least off-station for a short duration. Compartements can enhance the shielding and make it hard to do serious damage to the inhabitants.

The drawbacks are however that the colony will need oxygen and water. Oxygen can be generated from plants and through chemical processes. Plants require water, however, which has to come from somewhere. There may also be an alternative (backup or primary) nuclear power plant which will require fuel (hydrogen, helium, water, plutonium or similar). Also at least a part of the construction materials need to be imported, increasing the cost of building. Another drawback is the need of repairs. The colony needs constant repairs to stay operational, especially as older the colony gets. And the population growth has a very specific limit, after the water, air and space run out you have to either expand the colony or send people elsewhere.

The space colonies are usually present in science fiction around LaGrange points, in the asteroid belts and orbiting some planet on a stable orbit. The location of the colony also gives an indication of it's use.

Orbital space colonies are usually for commercial and military use. They may provide a port of call to off-planet traders, a base of operations for planetary security forces and such. Their industrial capacity is usually concentrated on ship and food manufacturing.

LaGrange colonies are usually built for their location. It is fairly easy to throw material from a planetary object to the LaGrange point and make it stay there. This makes, say an Earth L-5 colony a nice industrial center as they can get materials thrown from the moon, process it and sling it towards earth, for instance. Or sell it to traders passing back and forth. They are waystations but may also function as a way to ease the population growth issues on the planet below. These stations are usually huge and don't serve any particular reason except supporting the local population.

Asteroid colonies aren't usually very big. They might also be completely temporary, only existing until the asteroid the colony is built on (and the asteroids nearby) have been exploited. The colony usually has some installations on the surface of the asteroid but most of the habitation and basic operations are under the surface. Nevertheless, the population of an asteroid colony composes mostly from miners and engineers and possibly their family. The colony might not be for habitation at all, miners and engineers only being there for a certain tour of duty. Abandoned asteroid colonies are the favourite bases for space pirates and smugglers since they usually are pretty functional with some repairs, have all the facilities and have lots of space. If this is an issue, there might be regulations about blowing up abandoned space colonies every now and then.

Colonies, surface

I seem to pace around certain ideas from time to time. I think it is a process of refining ideas for me. Anyways, today I thought about colonies.

In the legionverse science fiction setting of my creation, there are two types of human settlements: established worlds and colonies. The distinction between the two is that worlds have at least 100 million inhabitants (legal minimum set by Imperial Senate) and have a representative in the Imperial Senate as a consequence. Worlds also have the right to establish and govern colonies. People are free to establish colonies, but Imperial Law requires that the colony must be associated either with a specific world or be governed by the Imperial Navy. Illegal colonies found are immediately put under authority of the Navy.

Now, considering a colony. It is a permanent but relatively new settlement built by a relatively small group of people, a few hundred adults at most in the beginning. They probably have limited supplies, tools and a limited connection to the motherworld. Therefore the equipment they do have with them is concentrated to keep the colonists alive long enough that they can build shelter and start producing food (and oxygen, if needed).

Well-prepared (and/or funded) colonists might send an advance party to build the shelters for the colonists to inhabit. They might be robots, a group of volunteer colonists with the necessary skills or hired hands. What to send depends on technology and ease of travel to the location. Robots would be favoured if using humans is risky or expensive but humans probably would be used if robots are not trusted or if they are not flexible enough in their decision-making.

Now, let us assume that the colonists have shelter and have started producing food for themselves. The next goal would be to build a technical infrastructure. Let us assume that the planet the colonists have settled has natural oxygen and water so these are not required. To speed up food production, machinery will be needed and machinery will need power. Solar power would be easily obtained, but the amount of solar energy available would be limited. Nuclear or fusion power might be too difficult to build (and fuel), fossil fuels might not be available on the planet. If hydrogen is needed for powering vehicles or generators, there must be some way to separate hydrogen from water or a source of raw hydrogen (a gas giant, perhaps?).

The colony ship might be available for the colonists, at least if the colonists or the colony backer owns the ship. In this case, the colonists might dismantle the colony ship and strip it's high technology for their own use. This would provide the early colony with a power plant, sufficient fuel for a while as well as metal from the hull to use for reinforced shelter, possibly even surface-to-orbit weaponry from the ship's turrets or a minifactory for manufacturing spare parts. The ship would give the colony a good supply of essentials for building the core of industry on the planet.

Now, let us assume that the colony has survived the first cycle around their star (let us assume that this is roughly 0.5-3 years) and have means to produce food, electricity and can repair goods and might have some rudimentary transports, harvesters etc. Now new items appear. At this point, the colonists have been isolated for quite a while, only in the company of each others. Tensions might rise and the colony risking dispersement (which might be dangerous or simply divide the resources available). This would prompt to create a way to settle disagreements peacefully, by arbiter. The settlement would probably attempt to follow the customs of their homeworld but might, especially if exiles or otherwise unhappy with the rules back home, create something of their own. This would become the basis of government and society and the early days would shape the future society.

Another question is maintaining contact to homeworld, a vital requirement. While a colony should be as self-sufficient as possible, the colony needs additional colonists and resources to grow. Also, some spare parts might not be available on the planet and getting these would require contact with homeworld or trade relations elsewhere. This requires, however, that the colony has something to trade for the goods they need. The motherworld might require food, industrial metals or something else. The preparation to provide these to the motherworld will probably be a top priority, depending on what they can easily provide and what the world can offer. The motherworld would certainly fund operations to get more resources that the colony can provide and therefore fuel the colony's rapid growth.

Time and Trade

Time is a difficult concept when discussing an interstellar society. Let us first assume an interstellar society with faster-than-light travel. This society has many settled worlds, space colonies and interstellar trade. A society that trades and otherwise intermingles between the stars has communications, treaties and other activity befitting a society, including possibly government, interstellar or planetary and/or both.

Now time becomes more significant. As a day, as currently understood, is a rotation of the planet Earth around it's axis. It can be possible for humans to adapt to different time cycles on other planets and time can follow either the local time (possibly having more or less hours in a day and such) or follow a specific calendar, such as the gregorian calendar on Earth. Or both. We can manage to follow GMT, EET and EST simultaneously, following, for instance Proxima-2 time and Terran Standard simultaneously should be no problem. As long as both are known.

But are they known? Let us assume that FTL is instantenous and takes us from one point in space to another in zero or nearly zero time from traveller point of view. Starship goes to jumppoint, disappears. In destination, starship appears. Simple. And if the time elsewhere (destination, departure point) stays the same, the ship returns when making the jump back, perhaps a few days later. Universal time is easy to maintain and no one gets confused. There might even be no official planetary times, just some adjustments to get the real feel of the planetary or station flow of time.

Let us now assume that the ship has travelled instantenously and there is a time lag of month per lightyear of distance. Much faster than speed of light. But a round-trip to Alpha Centauri takes almost 9 months on Earth while the traveller has been gone, from his point of view, a few days or a week or so. This is more confusing but it is possible to calculate. Travel also becomes a bit less tempting, as will trade. If taking care of immediate demands somewhere takes months at best, colonies on other starsystems tend to be very self-reliant and basically only ordering machine parts or other items not normally available in that system or planet. Trade focus is interplanetary and interstellar trade is more like spice trade in the 18th century, high-risk, high-gain. The items sought for might no longer be needed and the merchant is left sitting on a pile of useless goods. Still, zero-time travel from traveller point of view makes the trade reasonably profitable on goods that are always on demand. The merchant simply pops in, queries the planet for their needs. If none, he moves elsewhere to trade. Time on his ship passes more slowly than in the surrounding world meaning that he will have to synchronize his clocks after each jump. Time becomes more difficult to manage on other planets as well, as jump-ship time is out-of-date. If time lag can be accounted for exactly, time shouldn't be a problem. There would probably be several different calendars in use, one for each inhabited system or planet.

Third scenario. Let us assume that this FTL travel is not instantenous, say, jump time from Sol to Alpha Centauri takes a week in hyperspace. After this, ship arrives at edge of Alpha Centauri system and with good engines arrives at orbit of the inhabited inner planet(s) in a month or so. This cuts the travel time in short and creates incentive to systems to establish trading posts near the outer edges of the system. The planetary transports transfer the goods to the trade post and from the trade post, merchants never really entering the system. In this case there is also some lag, as the needs of a system or planet are known about a few weeks afterwards, but still less than the months. Time passes in this scenario as well, but less so and the time can be more easily managed.

Let us now assume two additional scenarios.

1) There is no FTL, but ships can achieve near-lightspeed speeds. A one-way trip to Alpha Centauri could take, say, 20 years from observer point of view. To the traveller, less time has passed. Far-flung interstellar colonies are practically self-sufficient. There is no interstellar trade, probably only supply ships and communications from government, if even that. Travel is mainly transportation of people for permanent settlement or possibly military expeditions, though even these might be rare. All time is system-local, probably based in colonization dates on the interstellar colonies. There might be estimates or even actual knowledge of current time back home, but it is probably used for reference if it is not useful for the settlers in some way.

2) The FTL time delay is determined by an unknown or possible random factor (quantum mechanics or such). If time delay is not noticed and there is no FTL radio, there is mainly local time, based on colonisation dates or some other notable event. Or it tries to maintain the Earth Standard (or equivalent) time.

A little on-off topic on this one, but hopefully enlightening on the matters of time, trade and interstellar space.

Space, revisited

Once, there was a blog. A blog where I thought, mainly for myself, stuff about space, universe and science fiction. Also some social science stuff and politics and philosophy. Then, I decided I should separate this "thoughty stuff" from the regular "I caught the cold today and feel slightly unhappy about some stuff".

The thoughty stuff happens here. The regular stuff happens elsewhere.

A slight disclaimer before I start. I am not a native english speaker, so please forgive spelling errors and some oddities in the typing. Native english speakers are however encouraged to send corrections and constructive criticism on the matter.