The 2300AD RPG – originally published by Game Designer’s Workshop in 1988 – presented an excellent gritty, realistic near-future hard sci-fi setting with lots of exploration, mystery, and interesting aliens. It’s also about to be republished by Mongoose Publishing as a setting for their version of the Traveller RPG!
One of 2300AD’s most interesting features is that the setting is built around a realistic (for the 1980s) Near Star List based on the Gliese Catalogue (2nd Version). FTL travel in 2300AD has a maximum range of 7.7 lightyears, resulting in the creation of “Arms” that extend from Sol to connect only the stars that are within this range of eachother (this limit can potentially be extended to 11.55 ly using Stutterwarp tugs, but this is expensive and uncommon).
There are three of these Arms, each colonised by a different political power in the setting – the French Arm, the Chinese Arm, and the American Arm. The French Arm stretches “upwards” from Sol towards Galactic North, ending at the orange giant star Arcturus. The American and Chinese Arms share the same beginning, but split off so that the American Arm heads Coreward/Spinward while the Chinese Arm sprawls around the (galactic) southern part of the solar neighbourhood.
Unfortunately the Near Star List (NSL) has not been updated for the new version of 2300AD. A lot of stars have been discovered in the solar neighbourhood since the late 1980s (as shown on my Stellar Mapping page), and the locations and distances of existing stars have been greatly refined since then too – so how does the updated stellar data affect the Arms?
Quite significantly, it seems. Here’s a overview (made in Astrosynthesis) showing all of the Arms plotted on an accurate starmap consisting of the RECONS, DENSE and Hipparcos stars within 50 lightyears.
The systems with yellow labels are on the French Arm (routes are cyan), the ones with red labels are on the Chinese arm (routes are green), and the ones with green labels are on the American Arm (routes are white). The yellow dashed lines represent routes between two stars that were closer than 7.7 ly in the original NSL, but are actually more than 7.7 ly apart in the modern data. The red dashed lines represent routes that require connecting stars that don’t exist. As you can see, there are quite a few yellow dotted lines…
Next, we’ll look at the individual Arms in more detail and see where the problems lie.
Extending roughly Coreward from Sol, the American Arm contains five “broken links” that are longer than 7.7 ly.
- The broken link between Serurier (Ross 154) and Broward (Wolf 1061) is problematic, since there are no stars between the two that can connect them directly, and since both stars are close to Sol is unlikely that any have yet to be discovered in that region. Instead, the shortest way to connect them is via a circuitous route that goes from Ross 154 (Serurier) to AX Microscopii to SCR 1845-635 to Gliese 682 (Davout) to 36 Ophiuchi (DM -26 12026) to Wolf 1061 (Broward).
- The HIP 86287 (New Melbourne) to HIP 83762 (Ross 863) route is also troublesome, since there are no known connecting stars and the gap is particularly wide at 17.8 ly (which precludes stutterwarp tugs as a solution). Both systems are beyond the RECONS 22.8 ly sphere, which opens the possibility that there may be undiscovered objects out there – this means that fictional M dwarfs or brown dwarfs can be added to connect the two systems, though the length and geometry of the gap requires at least three such fictional objects.
- HIP 83762 (Ross 863) to HIP 82003 (Botany Bay) is another wide gap of 14.3 ly. In this case however, it is possible to connect from Ross 863 to HIP 84794 (Gliese 669) to HIP 83043 (Gliese 649) and then to Zeta Herculis (Kingsland). Gliese 669 also itself connects to Zeta Herculis.
- Gliese 667 (DM -34 11626) can connect to HIP 84720 (DM -46 11370) via HIP 80018. Incidentally, Gliese 667 is known to have planets around it!
- Gliese 661 (Red Speck) can connect to Alpha Lyrae (Vega) via 2MASS 1835+325.
The Chinese Arm covers much of the solar neighbourhood “below” Sol (towards Galactic South), and includes several well-known stars. Officially, it begins at Delta Pavonis, which is reachable from Gliese 682 (Davout) on the American Arm. There are several broken links/points of interest on this Arm:
- The Delta Pavonis to Gliese 682 (Davout) link is broken, but they can connect via Gliese 693.
- The link between Gliese 832 (Xiuning) and Gliese 1 (Hunjiang) is broken, but the stars can connect via Epsilon Indi.
- “Rho Eridani” is actually two unrelated stars (Rho 1 and Rho 2) that are both hundreds of lightyears from Sol – the star in its place is actually “p Eridani”. Evidently, the authors of the original map misread the lower-case “p” and thought it was a greek lower-case “rho” (ρ), and this error was propagated in later editions.
- The Delta Pavonis to Beta Hydri and the p Eridani to 82 Eridani links are broken, which means that they (and Zeta Tucanae) are isolated from the rest of the Arm. There are no known stars able to connect them to the Arm – fictional red/brown dwarfs or stutterwarp tugs would be required.
- Although there are no known stars between p Eridani and 82 Eridani, 82 Eridani can be reached from Tau Ceti (and Epsilon Eridani) by going to Gliese 1061, then to DEN 0255-470 and then to 82 Eridani.
- Ross 780 (DM -15 6290) and Gliese 908 (DM +1 4774) are separated by 7.71 lightyears, which is [i]just[/i] over the stutterwarp range limit (by a mere 600 AU or so). This could be handwaved away as being within the operational tolerances of the stutterwarp drive, or an alternate route between the two systems via either Gliese 1002 or Gliese 1005 can be used instead.
- The DM +20 5046 (Doris) system is a fictional system that does not exist – in fact, the EQ Pegasi/Ross671 finger is a dead end. A K5 V primary seems a little bright to be unknown at this distance from Sol, which makes it hard to justify this star’s existence in this location. The closest system not on the Arm is Ross 775 (a close M V binary pair, unlikely to have a habitable world around them), which is 7.98 lightyears from Ross 671. The best solution is probably to relocate Doris’ worlds to Gliese 1002, which is a solo M V star (incidentally, Kanata – Doris’ mainworld – should be tidally locked to its star in either case).
- Qinyuan is not shown on major route on the Chinese Arm, but it is located in the UV/BL Ceti system.
The French Arm extends “upwards” from Sol towards Galactic North, ending at Arcturus (Alpha Bootis). It is the most problematic of the Arms, containing several broken links and four systems that do not exist.
- The link between Sol and Wolf 359 (Nyotekundu) is broken, so we’re off to a flying start! There are no other known objects between Sol and Wolf 359, and since it is so close it is very unlikely that there would be an undiscovered brown dwarf that can be used to connect the two. At a distance of 7.78 ly from Sol, this system would probably be too far to risk “pushing” stutterwarp drives to reach it on a regular basis, and the 0.08 ly extra distance (equivalent to 5040 AU) beyond the limit is somewhat too far to traverse using STL drives. The only solution is to take a very long route around that traverses most of the current Chinese Arm – this route would go from Sol to Barnard’s Star to Ross 154 to AX Microscopii to Lacaille 9352 to YZ Ceti to Tau Ceti to Gliese 1061 to Kapetyn’s Star to Sirius to Procyon to DX Cancri to Lalande 21185 (Bessieres)!
- the link from Lalande 21185 (Bessieres) to Gliese 380 (Neubayern) is also broken. The stars that connect the two result in a somewhat circuitous route, going from Lalande 21185 to DX Cancri to Gliese 388 to 2MASS 0937+293 to Gliese 380. A brown dwarf directly between the two stars would also be a viable alternative, however.
- Queen Alice’s Star and Kimanjano are both fictional systems that are required to connect Gliese 412 (Augereau) to Beta Canum Venaticorum and Beta Comae Berenices (Nous Voila). There is an alternate route to Beta Canum that involves travelling from Gliese 412 to Gliese 388 to Ross 104 to Xi Ursae Majoris (the somewhat misleadingly named “Kie-Yuma”) to HIP 57802 (DM +36 2219) to Beta Canum – the worlds of Queen Alice’s Star and/or Kimanjano could be relocated to one of the stars on this route. However, there is no alternate route between Gliese 412 and Beta Comae Berenices, so it may be better to use Queen Alice’s Star and Kimajano for that purpose since fictional systems would be required to connect them.
- Berthier is a fictional system connecting 61 Ursae Majoris (Joi) and Beta Canum – it could have been intended to be Gliese 438.1, but this is actually an orange giant located over a thousand lightyears from Sol. This system is likely to be HIP 57050 – an M4 V star that is accessible from HIP 57939 (see below) and connects to 61 Ursae Majoris (HIP 57050 also is known to have a planetary companion).
- the 2300AD maps are somewhat ambiguous, and it could be that Henry’s Star (Crater) actually connects 61 Ursae Majoris to Beta Canum instead of Berthier. Henry’s Star is HIP 57939 (a.k.a. Gliese 451 or Groombridge 1830) – this is a metal-poor G8 VI subdwarf star that is known to “superflare”, so it wouldn’t be a good place for a habitable planet at all. That said, Crater isn’t all that habitable anyway, and as luck would have it the 2300AD Colonial Atlas mentions that Crater is regularly bombarded by flares from a companion star that is now known not to exist, so this works out pretty well!
- the link between Beta Comae Berenices and HIP 66459 (DM +36 2393) is broken, but HIP 66906 can be used to connect them.
- the link between HIP 66459 (DM +36 2393) and HIP 67422 (Hochbaden) is broken, and there are no known connecting stars. These are far enough from Sol that a fictional brown or red dwarf could be added to connect them though.
- the link between HIP 67422 (Hochbaden) and Eta Bootis (Aurore) is broken, but WD 1345+238 (a white dwarf from the DENSE catalogue) can be used to connect them. This also connects to Alpha Bootis (Arcturus).
- Gamma Serpentis (the Käfer homeworld) does still connect to Arcturus via HIP 75187 and HIP 72848.
- Vogelheim is a fictional system. It could be replaced by HIP 54646, which is the next star out from HIP 57087, towards Pentapod Space.
- the Bayern Corridor is described (in 2320AD) as being along the route to the Pentapod Homeworld (which is past HIP 57087). However, this would have been an extremely circuitous route for the Bayern to take to the Pleiades – a much more direct route would be to leave the Solar Neighbourhood from the vicinity of Omicron 2 Eridani on the Chinese Arm.
It is possible to squeeze the existing Arms into the realistic star map, but the significant problems with the French Arm reveal the proverbial elephant in the room, which is that the Arms do not follow the “natural flow” of the actual 7.7 ly routes between the stars – instead they leap across gaps that separate them. This is illustrated nicely at Sol itself – the only way to reach the surrounding stars from Sol (while remaining within the 7.7 ly limit) is to travel from Sol to Barnard’s Star to Ross 154 (Serurier) to AX Microscopii, from which one can join a web-like network of systems that extends in several directions. However, 2300AD has the French Arm leaping a gap to Wolf 359, and neither the American nor Chinese Arm go to AX Microscopii at all and leap to Wolf 1061 instead!
The animation below shows the real network of 7.7 ly links around Sol, along with the 2300AD Arms. The “real” network is shown as the grey links between stars (expand the video to full size to see the detail). This significantly changes the astrography of the setting, and will be discussed in subsequent posts.
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