In May 1996, an autonomous resupply vehicle docked with Russia’s ailing Mir space station. It carried the usual items — food, clothes, scientific equipment — along with much more cherished ones. The American astronaut Shannon Lucid received M&Ms. For the two cosmonauts, Yuri Usachev and Yuri Onufriyenko, there were perfume-scented letters offering a welcome respite from the smells of the space station, which astronauts have likened to body odor, trash and hot metal.

Films and books may focus on the gritty strength of explorers, but in their diaries they speak with almost motherly affection for gentle touches of home. Space crews in the past have delighted in the scents of fresh tomatoes, lemons and apples, as well as recordings of rainfall or cafe chatter. The psychological value of these things is considered high enough to warrant the extreme expense of delivery. (A single apple costs around $300 to launch to orbit today aboard a SpaceX Falcon Heavy rocket.)

For those spacefarers who will one day go to Mars, the cost will be higher, the distance greater and the conditions far more dangerous.

Many experts suggest that Mars settlers will need to live inside heavily engineered habitats, protected from a world with high radiation, a thin atmosphere and toxic dust storms. They will probably spend much of their time in small, crowded structures with little privacy. Communication with Earth will require at least three minutes each way, making live calls from home impossible even during emergencies. Proposals typically call for round trip journeys of two years. There will be no care packages with truly fresh touches from home.

There are nevertheless those who would try to make a new home on Mars, though even the most ambitious proposals don’t put humans there until 2029 at the earliest. In the meantime, the Mars Society offers a chance to rehearse extraterrestrial living in some of the most Mars-like locations on Earth, as well as to run experiments meant to prove out sustainable approaches to survival (such as using bacteria to create edible protein).

At the Mars Desert Research Station in Utah, crews of up to seven work and sleep in a small cylindrical habitat connected to a dome, a greenhouse and an observatory by narrow enclosed pathways so that participants can move between facilities without breaking the simulation. Among barren, rust-colored desert, they live as Martians might, for a few weeks per mission, running experiments and recording findings.

M.D.R.S. is by no means a perfect analog for life on Mars. Crew members’ suits aren’t really pressurized; the airlocks aren’t locked. The gravity is stubbornly earthlike, and missions last for weeks instead of years. Problems that might spell doom on the airless Mars can be solved by a car ride to the hardware store. If M.D.R.S. one day proves valuable to space exploration, it is more likely as a kind of altar to Mars than as the final word on outer space ergonomics. As space launch deadlines perpetually get pushed back by NASA and SpaceX alike, crews at M.D.R.S. continue to tend to this bit of Mars on Earth, carrying a dream and keeping it tangible along with fellow believers.

Andrea Orejarena and Caleb Stein are multimedia artists based in New York. Their work uses the intersection of technology, memory and desire to explore American mythologies and narratives. Their forthcoming book, “American Glitch,” examines fact and fiction in the U.S. landscape.

Kelly Weinersmith is an adjunct faculty member in the department of biosciences at Rice University. Zach Weinersmith makes the web comic “Saturday Morning Breakfast Cereal.” Their new book is “A City on Mars: Can We Settle Space, Should We Settle Space, and Have We Really Thought This Through?”

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