I can't help but feel that the Space 1889 rulebook misses two careers which have considerable potential, namely the missionary and the policeman. In order to rectify this, here are my takes on these careers:
Bringing the word of God to the unenlightened, from the East End of London to Darkest Africa, and the Steppes of Mars to the Jungles of Venus. Although most of the Churches are still deliberating on whether Martians and Venusians have souls, the men and women who preach among them believe they do, and can be saved. Of course, not all missionaries are dedicated men and women of God; some only feign this in order to make a living exploiting the charity of the credulous...
Enforcing the law of the land in the four corners of the Empire. Although the British Policeman does not carry firearms as a matter of course, firearms training can be obtained if needed, or from a previous career.