(copyright A.Goddard February 1999)

Notes to the Stellar & Planetary Orbit Calculations table:

• In the table, radius refers to the distance from the centre of the planet, altitude refers to the height above the ground.
• The geosynchronous orbit is one where the orbital period equals the rotational period of the planet. A special case of geosynchronous orbit is the geostationary orbit. This is an orbit whose plane matches the plane of the planet's equator, and therefore an orbiting body (such as Earth's Gateway on the orbital tower) appears to remain static to ground-based observers.
• The stutterwarp zone is that area bounded by the 0.0001g and 0.1g limit for the chosen planet, as per the rules. For planets within the STL zone of a nearby star, or satellites within the STL zone of a nearby planet, the FTL point may not exist as calculated above. That is, any location within a stellar system has the lowest possible stutterwarp speed depending on the sum effect of all the bodies within that system.
• The orbital data is provided to allow users to calculate the details of two stable, circular orbits. The half-angle is a measure of an orbiting body's footprint over the surface of the planet - the number of degrees to the apparent horizon from the sub-satellite point. Similarly, it is the maximum distance in degrees of arc measured from a point on the surface of a planet directly below the satellite that the satellite may still be 'seen' from.
• The transfer ellipse information provides the minimum values required to transfer between orbits 1 and 2. For 2300, interface craft have to travel between ships discharging in the cutoff zone and low planetary orbit. Two burns are required - the first to break out of a circular orbit into a transfer elliptical one, the second to circularize the transfer orbit at the furthest point of this ellipse. Positive values of Delta V reflect an increasing size of orbit (orbit2>orbit1), negative values reflect a decreasing size of orbit (orbit2<orbit1). The transfer time is the period taken between orbits 1 and 2 - this is the half period of the full elliptical orbit.

• The presence of gravity on the human body has important physiological and psychological benefits. Without gravity, for example, bones decalcify and muscle mass is lost. In addition, a reinforced sense of "up and down", along with the straightforward use of normal human utensils helps relieve subtle long-period stress.
• In 2300, some starships and many large space structures use the only known form of "artificial gravity" to counteract the negatives associated with long-periods of zero-g. This "gravity" is an acceleration, and is generated by rotating a pressurised habitat at a set rate. In a process identical to the forces felt on the body when cornering in a car, a force is felt by any object resting on the inside curved surface of such a spun habitat. This force is called centripetal force and it acts outwards from the centre of rotation along a line perpendicular to the curved surface. The amount of this force is tied in with the radius of the habitat and the rate of its rotation: both these values can be adjusted in the above table.
• Coriolis effects for small radii and high spin speeds are very marked. 2300 tends to gloss over the unpleasant psychological effects of these. In the game, the designer is allowed minimum habitable rotation radii of 6m in what is presumably a 1g field at a character's feet (say a 8.5m radius). In reality the centripetal force would probably be set as low as practically possible - low enough, for example, to keep liquids in mugs on a table and help prevent nausea when moving around the habitat; while advanced tailored drugs and exercise would address any bone and muscle mass loss. Research has demonstrated that while most people can cope with spin rates of around 1 RPM, few cope well with rates of 3 RPM or over. Given these facts, I'd suggest that only the largest structures (Gateway, Station Arcture, La Salle Station) would be likely to support full, comfortable, 1g accelerations at their rims - most ships that employ spin would be restricted to fractions of a full gravity.
• Thanks to KevinC for directing me to some of this information.

• Many starships in 2300 combine Hydrogen and Oxygen to generate electricity, either by using magnetohydrodynamic turbines or fuel cells. The waste products of these two methods of power production (namely water and peroxide) can be condensed and stored on board for later cracking and reuse. However, for many commercial vessels operating on routes with abundant facilities it will often be easier and cheaper to simply vent the waste overboard. As a result the mass of these ships varies over time. This change in mass is not covered in the standard warp efficiency formula. The above table uses a better formula based on the rate of change of mass, to calculate the time taken to travel a set distance at a number of warp efficiency rates.
• Three different warp efficiency rates are listed, using the baseline WE=1 value. These are 0.645 AU/day and 6.45 AU/day rates, for use in slower-than-light zones (the two different figures are offered depending on the user's preference and interpretation of the rules). Earlier tables covering Stellar & Planetary Orbits and Planets and Satellite Orbits enables calculations to be made regarding the size of the stl zones around stars, and around those planets which lie outside solar stl zones. The third rate offered is the standard ftl speed of 1 LY/day, for use in calculating travel times between the stars.
• The distance entered is automatically regarded in the calculations as a distance in AU if an stl warp efficiency is chosen, and a distance in light years if an ftl rate is picked.
• The time taken to cover this distance is given in days, hours, minutes and seconds. However this figure is only correct if enough fuel is carried for the trip: the information box will remark whether fuel requirements exceed what is carried. For acceptable trips, where fuel tankage exceeds how much fuel is used, the information box lists the percentage of the carried fuel used for that trip. Occasionally, when bizarre figures are entered in the black boxes, "NaN" might appear in the calculation boxes. This stands for "Not a Number", and is Javascript's way of "throwing a wobbly".
• The fuel rates for MHD turbines and fuel cells uses the figures listed in the Star Cruiser Naval Architect's Manual. While these are at odds with the figures listed in the Director's Guide (page 65), the Star Cruiser rates are officially sanctioned as the correct ones: 100 tonnes per MW per week for MHD turbines, and 75 tonnes per MW per week for fuel cells.
• Thanks to Thomas Vickers for requesting this calculator, and thanks to Bryn Monnery for clearing up the fuel efficiency issue.