Codification & Future Time Periods
Speculative designs for space habitats are often designed for contexts that are categorically different from each other. Whether it be the size, population, technology, or any other aspect, the combination of these factors determines in some way the future time period that the design’s construction may be plausible.
I have included below a codification for the size, method of gravity-simulation, and population (a slight modification of the system originally authored by Isaac Arthur in 2014).
Gravity Simulation
[G] Natural Gravity
[Z] Zero/Micro-gravity
[R] Rotating Gravity
[A] Artificial Gravity*
[N] Not Applicable
Size
[1] 10^1 meters diameter
[2] 10^2 meters diameter
[3] 10^3 meters diameter
[4] 10^4 meters diameter
etc…
Population
[i] 10^1 persons (10)
[ii] 10^2 persons (100)
[iii] 10^3 persons (1,000)
[iv] 10^4 persons (10,000)
etc…
Examples:
Lunar Gateway : Z2i
Kalpana One : R2ii
Virga : Z7ix
Banks Orbital : R9x
Lunar Base : G2ii
Starship Enterprise : A2iii
I have applied these factors to a timeline showing where they might have a chance of appearing in our future. I have broken this timeline into three periods that I view as categorically different from one another. I have chosen to name these time periods the Near Term, the Medium Term, and the Far Term. These terms are relative and only represent a speculative outlook from the time of writing (2020). Indeed, when the year 2250 comes around, the Near Term will carry a whole different meaning.
The purposes of making these distinctions is for contextualizing and comparing speculative designs for space habitats against one another. By highlighting two distinct milestone groupings in the timeline based on the benchmarks as relating to size, population, and gravity simulation, the future time periods are separated by the achievement of any one of these benchmarks. These benchmarks are not expected to be simultaneously achieved, but the achievement of any one of these benchmarks signals a great change in how space is being used by humans. I have arranged these milestones on the timeline in the order I expect them to be achieved (if at all).
The first milestone period contains the following benchmarks:
Rotational gravity simulation [R]
Size exceeding 10^3 meters [3]
Population in space exceeding 10^2 persons [ii]
This means that the Near Term would end and the Medium Term would begin once we accomplish one of the following:
Occupy a rotating space habitat
Construct a space habitat having a diameter in the kilometers
Have a population in a space habitat numbering in the hundreds
The second milestone period contains the following benchmarks:
Artificial gravity simulation [A]*
Size exceeding 10^5 meters [5]
Population in space exceeding 10^4 persons [iv]
Similarly, the Medium Term would give way to the Far Term once we accomplish one of the following:
Occupy a habitat utilizing artificial gravity technology*
Construct a space habitat having a diameter in the hundreds of kilometers
Have a population in a space habitat numbering in the tens of thousands
In this way, a classification code for a given space habitat will telegraph the time period it was designed for. See below list using the same examples above.
Examples:
Lunar Gateway : Z2i : Near Term
Kalpana One : R2ii : Medium Term
Virga : Z7ix : Far Term
Banks Orbital : R9x : Far Term
Lunar Base : G2ii : Medium Term
Starship Enterprise* : A2iii : Far Term
I have applied my own time horizon estimates to the graphic above in order to provide an example, though these are my own estimates and others’ opinions may differ. I encourage the reader to assign their own time horizons to the above graphic, as the principle of the distinct time periods remains the same.
Note:
For the sake of convenience and simplicity, I have omitted the eccentricities that may occur in the designs for space habitats due to possible human augmentations. The underlying assumption built into the timeline outlined here is that humans will remain essentially unchanged between now and the far future. This assumption may or may not be true. Such augmentations might include the likes of radiation resistance, vacuum tolerance, micro-gravity tolerance, or even digital minds. I may address these aspects in a future blog post which will outline an alternate set of benchmarks.
＊ It is not my impression that artificial gravity is plausible or even possible, however such an advent (if possible) would certainly revolutionize the value proposition for the occupation of space.
