Travel

Fuel: A "unit" of fuel is defined as the amount of fuel (from a fusion fuel cell) needed to accelerate 1 ton of mass (weighed in 1.0 Gs) to 100,000km/h. So, to accelerate a 50-ton ship to 100,000km/h (standard cruising speed for most interplanetary travel) would require 50 fuel units. One fuel unit costs one credit.

Speed:
Atmospheric speeds are defined as travel at 15,000 km/h or lower.

Coastal speeds are defined as travel at 15,000 to 250,000 km/h.

Deep speeds are defined as speeds over 250,000km/h. Only one is on record with top speeds above 500,000 km/h, an experimental manned craft built by the famed pirate Archibald the Wayfarer. It had a crew of two (pilot and a robotic navigator) and completed one journey at approximately 700,000 km/h during a daring getaway.

Distance:
The megacorp planets and aeneas are all between 25 and 30 million km from each other. Briseis and chryseis are only 10 million miles from each other, but about 40 million km from Aeneas (the next closest planet). Nestor, the next most distant planet from the sun after the megacorp planets, is about 60 million km from Diomedes. Distances increase steeply from there. The distance between Castor and Pollux is about 3 billion Km, a frighteningly close distance between two star systems that has baffled astronomers for generations.

psycho-navigation: if you are not considering making a psycho-navigator (obviously a points issue) and if you don't feel like you'll be able to leave this information out of character (or if you just prefer not to know), please don't read this section, it is NOT common knowledge in the Gemini, and is basically known only by practitioners of psycho-navigation.
For those not "in the know", which is most people, psycho-navigation is essentially an cult of magic users. It is regarded as very dangerous, the domain of blackhearted and treacherous pirates, desperate and daring military commanders, or the greediest and most overconfident merchants. All the ships in the Gemini capable of space jump are well known (although people talk about secret examples...but it is a difficult secret to keep given the quality of modern sensor arrays) and have long and storied histories. Currently, there are 5 ships known in the Gemini capable of space jump: one has not been seen in ten years, one had a problem with it's jump drive, and the other three are still in operation:
1.) The "White Cat": The last ship built by Archibald the Wayfarer, the most famous space-pirate of all time. Like most of the other ships on this list, it did not consist primarily of precursor tech, but had only a precursor hull, the jump drive, and a few other minor K-tech components. At the end of his piratical career, Archibald declared that he and his crew had had their share of plunder in the Gemini and were setting off to plunder other systems: they would come back and let people know how to get back to the rest of humanity once they got back. That was ten years ago, and they have not been heard from since. Archibald's psycho-navigator is Themistocles the Wily.
2.) The "Sleipnir": owned for over a hundred years by Asimov Industries, the sleipnir has been a major source of technology for them and represents perhaps the only corporately endowed research vessel in the Twins: being recruited there as a scientist represents among the highest honors one can receive. The ship is regularly "seen" at the far reaches of both systems, performing archeological surveys, studying precursor tech, and engaging on various exploratory missions. the vessel is claimed by AI to be 90% K-tech, found nearly intact at an undisclosed location. Recently, AI annonced that the Sleipnir had suffered some technical difficulties during an experimental mission and had been recalled to Odysseus for repairs: because of it's high amount of K-tech, it is believed these repairs could take a significant amount of time. The Sleipnir psycho-navigator is Hylikee Barca.
3.) The "Medusa": The only warship capable of space-jump, commanded by Vladimir Ignatievitch, a mercenary with a fearful reputation rivaled only by the Lycurgans. He is also believed to engage in significant Piracy, although currently he is under a "permanent contract" with the Aeneans. Where Ignatievitch got the ship is unknown, but it is clear that only the space-jump engine is K-tech. His Psycho-Navigator's identity remains unknown.
4.) The "Monte Cristo": Owned by Tetsuo Hara, a powerful private citizen with many ties to corps. The monte cristo engages in high end delivery primarily between the two systems. The ship is about 40% K Tech. It is the largest of the jumping ships, being a cargo carrier, although it is also well armed, it being such a valuable and famous prize for pirates. The psycho navigator is Mia Cavalierre.
5.) The "Helen": A pirate vessel famous for numerous bank heists: the captain, calling himself Sparrowhawk, is extremely flamboyant and also apparently determined to outdo Archibald the Wayfarer. The psycho-navigator is Clytemnestra Mycenae.