I told you yesterday that I’d let you know when my copy of A City on Mars arrived. It did! Yesterday! I’ve already started reading it, and I’m already happy with it.

Finally, it’s a book about sending humans to space that takes a realistic position: no jingo, no hyper-optimism, and an awareness that enthusiastic boosterism about space travel is a cult-like religion. It sets up the contrast in the introduction: that there are space geeks who fervently believe in the importance of colonizing space for a variety of reasons (most of them bogus), and there are space bastards who keep crashing the optimism by pointing out the problems. The authors side with the space bastards. So do I.

My opinion is that humans are a kind of animal that is well-adapted to a broad range of climates, but are still dependent on a narrow set of environments — we require plentiful water, about 20% oxygen, trace amounts of carbon dioxide, an air pressure between 100 mm Hg and 800 mm Hg, about 1 g of gravity, etc., etc., etc. We can survive briefly outside that range, but we sure don’t thrive and prosper. If ever you’ve raised tropical fish, for instance, you know that living things are extraordinarily sensitive to minor deviations from their ideal environment, and humans also have restrictions we take for granted. Biologically, we’re unsuited to existence anywhere in the solar system outside our one planet — you know, the one we’re busy trashing, but which will never be as hostile and incompatible with life as any of the other places in space.

We’re never going to build viable colonies elsewhere, even on Mars, which is the next best option outside of Earth, and even at that it’s poisonous and dead. I think I’m more negative about the prospects than the Wienersmiths, but it’s still a relief to find a source that recognizes the realities of life in space. It’s reassuring, even.

I have Zach and Kelly Weinersmith’s book, A City on Mars, on order. It hasn’t arrived yet, but I’m seeing excerpts all over the place that let me know I’m going to find this one interesting. It asks all the important questions!

Can you have sex in space?

Astronauts have confirmed over the past few decades that in space, the flesh is willing. But truth be told, we don’t even know if you can actually do the fun part of making space kids. While the moon and Mars provide some gravity, a vast majority of data on space physiology comes from orbital space stations, where astronauts hang in constant free fall. Weightlessness is ideal for physics problems but not for intercourse; a nudge toward you will send you flying backward with equal and opposite momentum. Without the familiar frame of reference provided by Earth’s gravity, concepts like “top” and “bottom” are without physical meaning. All of this will make the orientationless mambo awkward. The space popularizers James and Alcestis Oberg wrote in 1986 that those who attempt the act “may thrash around helplessly like beached flounders until they meet up with a wall they can smash into.”

Assuming this is undesirable, you’ll want something that keeps people together. The engineer and futurist Thomas Heppenheimer called for an “unchastity belt.” Another concept, pitched by Samuel Coniglio, a former vice president of the Space Tourism Society, is the “snuggle tunnel.” There’s also Vanna Bonta’s 2suit, which would keep a weightless couple connected via Velcro straps.

I don’t know…those options sound like they could be experimented with here on Earth, so why go to space?

After thrashing around helplessly like beached flounders, you may work up an appetite. What to do next? Have you considered space cannibalism?

Professor, prolific author, and triathlete, Dr. Erik Seedhouse wrote an analysis of space cannibalism in “Survival and Sacrifice in Mars Exploration.” We don’t know Mr. Seedhouse personally, and he didn’t respond to our email, but we will note that his book’s index contains precisely one entry on “behavioral challenges,” a very important topic, but five entries on the gustatory mode of crew integration.

Seedhouse asks: “Imagine you’re stranded on the Red Planet with three crewmembers. You have plenty of life-support consumables but only sufficient food to last one person until the rescue party arrives. What do you do?… One day, while brewing coffee for breakfast, you realize there are three chunks of protein-packed meat living right next to you.”

He argues that the largest people should sacrifice themselves first, since they both consume and provide the most food. We don’t know where Seedhouse would fall in the buffet line because we couldn’t find his height and weight online, and honestly we’re scared to ask.

Mostly because his book includes a weirdly detailed look at how to butcher Homo sapiens. Also, on page 144, the reader will find a photo of ten astronauts floating happily in space, with the caption: “In the wrong circumstances, a spacecraft is a platform full of hungry people surrounded by temptation. Is it wrong to waste such a neatly packaged meal?”

Is one of the space people Elon Musk? I think that would influence my answer. He doesn’t look particularly appetizing, so this would be a question of performing a distasteful service that would benefit all of humankind.

I’ll let you know when my copy of the book arrives. The first thing I’ll be looking for in the index is “spiders,” because I think they’d thrive particularly well in low-G environments. Is the city on Mars specifically for spiders?