Star Marshal - Supreme Commander of the entire Space branch of the military

Constellation admiral /Marshal - Responsible for entire regions of the command

Nova admiral /Marshal - Commands hundreds of ships

Fleet admiral /Marshal - commands a fleet containing several dozen ships

Senior Officers:

Quasar - Equivalent to a Navy Captain or a Colonel, commands a battle group

Commander - Commands a ship or unit of several small ships

Sub-Commander - usually a 2 i/c of a ship or unit, or commands a sub unit

Junior Officers:

Nova Lieutenant - an experienced junior officer, commands a cell or section is training for their first spaceship

Star Lieutenant - a less experienced junior officer

Subaltern - a newly commissioned officer

Star Cadet - an officer in training

Senior NCO:

Chief Steward - senior most enlisted rank, usually only one or two per unit

1st Steward - a veteran NCO with years of experience, usually one per sub unit

2nd Steward - a senior nco with extra leadership training

Ships Sergeant - Takes care of security and stop enemies from boarding the ship

Astronaut Sergeant

Astronaut 1st Class

Astronaut 2nd Class

Astronaut Apprentice

Recruit Astronaut

All astronauts are used as crewman and help with the maintenance and day to day processes of said spaceship.