A very good rulebook and great toolkit for starting a "hard" science fiction d20 game. It's also very lethal when it comes to combat and death.
Most importantly, you do not have to start off as a 1st-level character, thanks to the Prior History rules, adapted from the Classic Traveller Prior History rules.
Starship combat is hex-based (a minor inconvenience that I'm hoping to rectify, no offense, but that my own personal preference is grid). Includes starship creation rules.