3 ideas
The narrator explicitly declines to give a full journal of the voyage. Instead, instrument readings, temperatures, supplies and routine mechanical concerns give the impossible trip a practical, matter-of-fact texture that supports its credibility.
The author introduces one fictional physical principle, apergy, as the natural opposite of gravitation. He works out its practical engineering consequences as if it were ordinary physics, including shielding, steering, and controlling thrust and descent. This treatment gives the voyage's machinery a scientific rather than magical feel, although the book also includes other marvels such as the secret order's psychic powers.
Mars is presented as a technically advanced, officially materialist civilization. It has passed through failed political experiments, and religious belief survives only among a persecuted secret minority. The imagined society works as a distorting mirror for Victorian debates over democracy, socialism and secular rationalism. Its efficiency is shown producing moral and spiritual emptiness, so the political critique arrives disguised as travel reportage.