It's the hero, the astronaut. He's the man who defies all odds and travels in a tin can into the most inhospitable environment humans could imagine. There's no life there; it's empty, lifeless and dead. The tin can contains an abbreviated biosphere capable of supporting human life for a limited amount of time.
With the exception of the moon walk, there's not really been any human exploration of space. The experience is always highly mediated by the technology required to sustain human life. In the past (on earth), explorers had sensual experiences that involved direct interaction with the explored environment. Space exploration has mostly been a visual and interior experience. A more direct immersion in “space” would result in the instant death of the explorer.
The “I” who decides to on embarkation and narrates the story of space travel appears to be a cartesian subject. The astronaut must put his unconscious into abeyance for the duration. The unconscious must remain unconscious, only the trained ego of the astronaut flies, all internal demons are locked up. It's the pre-Freudian human who travels in space.
A little more difficult is the issue of the microbiome. We humans contain multitudes. We are both humans and a cooperative life form that requires a functioning of a vast internal ecology. When the human travels in space so do the hundred trillion microorganisms that live in his intestines. We do the best we can by scrubbing off the bacteria and crustaceans that live on the outside of our skin, but the creatures on the inside have to go along for the ride.
It's quite conceivable that the first life forms from earth to colonize mars will be bacteria that have hitched a ride on our rockets. Those bacteria will be the evolutionary seed that may start a whole new chain of events in a radically different biosphere. Martians will evolve to survive on mars. It's not that they'll be specifically adapted or “tooled up” to the martian environment. Evolution doesn't work that way, it's not an optimization algorithm looking for a single best solution. Multiple correct solutions can and will coexist. There are millions of right answers to the question of what a martian looks like.
Our scientists want to eliminate the possibility of “contaminating” Mars because it will complicate our search for life there. In this too we want to eliminate our unconscious. Somehow every aspect of ourselves and our voyage must be conscious and accounted for. Scientists are very good at this kind of self delusion. Once they fail at non-contamination, we'll hear about how they can keep track the natives versus the aliens.
Of course from a slightly different angle one could see human bodies as the space ships created by bacteria for transport to mars. Humans have been selected because they're quite clever with machines. Bacteria have survived in space and could easily flourish on mars. Except as transport, humans aren't very well adapted to the task.