Last night I started taking a look at the TravellerMap data again, having noticed that the wiki pages for some worlds will note the climate of the world yet I don't see where that gets reflected in the second survey format data. I did discover that system world count is reflected in the second survey data, something I had overlooked before.

I set out to identify the "most remote" world in the TravellerMap data, but I'll have to make use of a more clever method of finding it than I was using (brute force distance matrix), but just in case anyone else has already done this: what are the most remote worlds in Traveller? Remote being defined as "longest distance to a neighboring world".

Reading further in the Reformation Coalition Equipment Guide, which I got when wanting to read about the personal reentry kits, I found the section on communications devices and noted that many of the uplinks are limited to 3000 km range when contacting a ship in orbit. Planning missions around those kinds of limitations can be kind of interesting.

Often times communications systems will have additional restrictions when communicating with an orbiting object - for example that object must be at a minimum of 10 degrees elevation relative to the horizon and ideally more like 15 degrees. Perhaps omnidirectional communicators will only work out to 300 km, but if you have a directional, self guiding antenna you get more like 3000 to 6000 km. As I mentioned before, to me it adds flavor to the game if celestial conditions can be described and even more if they actually influence surface operations. As the ability of Traveller ships to hover perpetually for long periods of time over a single point, I think I'm just outright going to remove that ability and set about reworking slower than light propulsion rules for "IMTU".

So, taking the system I had been using and modifying it somewhat, presume that Home is a uncontacted, human TL3ish world for which the players need to conduct a covert surface operation. They need orbital communications support and need to minimize movement during the daylight to avoid detection. Home has a semimajor axis of around 1.05 AU and the equilibrium temperature is about 8 degrees C, quite a bit cooler than earthlike conditions. It has an axial tilt of 31 degrees and this takes place during the (northern hemisphere) winter solstice.

Their ship is Hamiltonian which has released a communications relay satellite. The surface operation is at a fairly high latitude and geostationary satellites would be uncomfortably low on the horizon for consistent communication. The solution the players come up with (out of many possible solutions) is that Hamiltonian is in a Molniya-like orbit, with a eccentric, high inclination orbit which consequently dwells at apogee over the latitudes the players are concerned with for fair amounts of mission time. An opposite molniya orbit is selected for the relay satellite to cover the times that Hamiltonian is below the horizon. This is not an optimal solution, but part of the game would be in selecting orbits for ground support given the limitations on communications equipment. Both spend a lot of time further than 3000 km from the ground station.

Hot Chi, the system's gas giant, is above the horizon most of the night and presently at Opposition and as bright as it will ever get, which is around the brightness of Saturn from Earth. For the first five hours of the mission, Hamiltonian is high in the sky but it does locally set around 5h25m into the mission. That's ok though, the communications relay has been high enough in the sky to handle communications since 2h18m. Not computed or shown here though is the time that Home is between Hamiltonian and the Relay, which would also serve to stop communications between the ground crew and Hamiltonian.

Given that it is a cold world, they are at high latitudes and it is that hemisphere's winter, the mission temperatures will be bitter cold. The world has no moon, the nights will be pitch black except for starlight on a world with very little in the way of artificial lighting. The locals are unlikely to be out and about in such conditions, but there is a time limit: at 6h46 minutes astronomical dawn starts, and nautical dawn begins at 8h9m. For the military this is BMNT - begin morning nautical twilight and tactical night operations would usually stop at this point. The players would presumably want to be hunkered down somewhere warm and hidden to wait out the day. There's an additional risk, though above the horizon, neither Hamiltonian or the communications relay are high enough in the sky to provide solid communications, at about 5 degrees elevation each, right at that point.

and, of course, the obligatory animation depicting the position of the surface operations force, the direction to the star (blue arrow), and positions of Hamiltonian and the communications relay satellite:

I realize this is not very Traveller, but it's the kind of thing that some of us like and hopefully I can build into our games. I am curious though, some people have hinted at game systems that do have more of a "hard scifi" feel to them for which this sort of thing would be built into the game mechanics. What games would those be?