Leonid
The novel’s protagonist is a revolutionary and scientist traveling to Mars to study what appears to be an actual working socialist utopia. Leonid has been chosen by the Martians precisely because he is Russian at a time when the 1905 revolution seems to them to hold the greatest promise for earth to fulfill their own destiny. Before he is a scientist, therefore, Leonid is the perfect emissary because he is an revolutionary. The choice to become emissary is not his own and, in fact, he does not learn the full details of what is going on until some time into the mission.
Menni
The chief engineer of the Martian expedition to earth which has come to seek an emissary. As a result of his ability to speak Russian, he and Leonid bond and establish a friendship. Back on Mars, however, Menni’s duties are transferred to a commission charged with the colonization of Venus and he fades into the background. He returns to the foreground of the narrative with a vengeance in the sequel titled Engineer Menni.
Netti
Netti first as a doctor assigned to help Leonid overcome his difficulties in sleeping on the expedition to Mars. Since Leonid is kept in the dark for much of the beginning of the novel, a humorous bit of confusion is associated with Netti, whom he at first assumes to be male. Once he learns the truth, Netti’s role expands into that of romantic partner.
Sterni
Sterni is a part of the crew on the expedition to earth that retrieves Leonid. He is coldly analytical; a Martian intellectual who calls for the extermination of earthlings because their movement toward socialism can only end in a fragmented disaster spelling trouble for Mars. Leonid does not take kindly to his solution for dealing with what is still only a potential problem.
Nella
Nella is the facilitator of Martian child care, but more importantly for the purposes of plot, she is the mother of Netti. It is in that capacity that she shares a very significant piece of information with Leonid to which he was previously ignorant: that Netti used to be married to Sterni.
