We could begin with the brain encased in the skull, but I prefer the chambers of the heart, and moving out, the veins and arteries, rib cage, muscle, and fat and then the skin that hugs it all into the shape of my body. A possible container for a possible soul. I’m lying on the narrow foam mattress, under a comforter on top of a sheet. Beyond this bed is my room, the medium-size walk-in closet. The door is shut. Beyond the door, the second-floor mezzanine and more doors, behind which some of my crewmates are sleeping. Below us, is the expanse of our habitat—laboratory, work spaces, kitchen, dining area—our home on some kind of Mars. Because it’s morning, I hear Oleg and Yajaira, the early exercisers, laughing as they contort to the demands of a workout video.
The thing about exercise is that it increases respiration and therefore carbon dioxide in the vicinity of the exercising body. Our habitat is outfitted with sensors, and within the first few weeks, we noticed spikes in CO2 levels after workouts. High CO2 affects different people differently. I evidently get light-headed, sleepy, and find it difficult to concentrate. Scott Kelly, during his year on the ISS, felt congested and had burning eyes and mild headaches. In the American section of the space station, high carbon-dioxide levels were a frequent problem, he writes in his book, especially when there was a larger crew and especially when the carbon-dioxide scrubber was malfunctioning or broken, which was unfortunately often. Of all the technical details in Kelly’s book, the carbon dioxide issues on the space station surprised me most for the frequency with which they’re mentioned, and the seeming lack of urgency afforded them by mission control.
Similarly, our mission support also wasn’t much concerned with CO2. The problem was especially pronounced when more than two people were exercising, but since space was limited, we staggered our workouts so no more than two people would be breathing heavily at the same time. Also, because the habitat was essentially a tent with little to no insulation—not a closed, pressurized system like you’d actually have on Mars—we could count on its draftiness for relief.
Our dome wasn’t the only scientific study on the volcano. Just a short walk across crunchy basalt sat a little gadget that monitored seismic activity, and farther up the slope was the Mauna Loa Observatory, a facility that has measured levels of carbon dioxide in the atmosphere since 1958. During our mission, the observatory made international headlines. On May 9, 2013, readings indicated, for the first time, that daily average levels of carbon dioxide in the atmosphere tipped past 400 parts per million. You can probably imagine what’s happened since. By September 2016, the monthly average never dipped below it.
The 400 ppm marker is mostly symbolic—nothing drastic happens when instruments tick off this reading. But put in a context of ever-increasing CO2 levels, the 400 ppm marker now feels, more or less, like a point of no return.
Still, the even more disturbing number to consider is the rate of change of CO2 concentrations in the atmosphere and how it relates to the now very rapid rise in average global temperature—a heat that is becoming destructive to humans and other living things.
We’re on pace right now, thanks to an upwardly mobile rate of change, to see CO2 concentrations exceed 500 ppm within fifty years. It’s a big deal because at this rate, global temperatures will increase by 3 degrees Celsius. And 3 degrees Celsius is a very big deal because of the subsequent devastation that accompanies this kind of hotness: sea level rise, more and more-deadly forest fires, liquified glaciers and ice caps, more and more powerful storms, mass migrations of humans, ocean die-offs, jellyfish rise-ups, threats to global food supplies, that kind of thing. Though not a closed system, the Earth is not exactly a leaky tent. Within our or our children’s lifetimes, we will know, viscerally, tragically, how very high levels of CO2 affect us all.
There are some people, often extremely wealthy people, who tend to see Mars as a plan-B planet, to save us from the ravages of a hotter Earth. It’s a proposal that carries a whiff of urgency, but it also flaunts an elitism that already plays out at home. In November 2018, as deadly fires ravaged California, wealthier citizens, for instance, Kim Kardashian, hired private firefighters to protect their homes. Say, for instance, that there were some way to transport hundreds to thousands of people to Mars, and then to house them there. Who would these hypothetical migrants, fleeing a chaotic Earth, be? With hypothetical tickets costing, according to Elon Musk’s most recent estimates, $200,000, certainly not people who make their living as librarians, electricians, sanitation workers, nurse practitioners, or line cooks, though you might imagine those are precisely the people you’d want to have as members of your community. But also, what would their ships look like? What about their Martian habitats? What does it mean to make a home, to call a place home? And how would they take care of their new home once they got there?
“I’ve often heard people say: ‘I wonder what it would feel like to be on board a spaceship,’ and the answer is straightforward. What does it feel like? That’s all we have ever experienced,” said the architect, author, and inventor Richard Buckminster Fuller. “We are all astronauts on a little spaceship called Earth.”
A vessel is a repository or a transport system. It is a ship that ferries people and cargo over oceans; it is a tube that moves blood, sap, or water; it’s a structure built on solid ground. A vessel is a body that holds an ethereal spirit or, as a womb, another body within it. It is a container, a shelter, a shell, a home or destination, a space that creates a sense of security, insecurity, or, possibly, adventure. It can be emptied and refilled, closed and opened. A vessel is defined by its boundaries, the shape that’s formed when interior and exterior coincide.
Our dome on Mars was geodesic in the sense that it is a hemisphere made up of triangles, a design patented by Buckminster Fuller in 1954, and popularized at the World’s Fair in New York City a decade later. Ours was covered in white vinyl and, on top of that, partially covered by a brown, black, and rust-colored camouflage tarp so that the brightness of its white against the red rocks of Mauna Loa wasn’t so gleaming from the distant road. This was in accordance with land-use permits and to keep a low profile on the mountain, a mountain which is sacred to the native people of Hawai‘i, and so also in accordance with Hawaiian cultural practitioners who had asked that the habitat respectfully be covered.
The dome featured one window, about two feet in diameter, which was installed only at the end of our first month. The window was important to us on Mars because the camo coverage significantly limited the amount of light that got through the shell during the day. On the ISS, researchers have installed LED lights that can be tuned to produce white light that’s slightly more blue in tone, which is thought to wake up the circadian system, and light that’s slightly redder, which is believed to calm it down. We had LED lights, but they weren’t so special. They were mostly track lighting, and never enough, it seemed to me. In addition to missing talking to Jill, being able to go for a bike ride, drinking beer, and eating fresh vegetables, it turned out I also missed sunshine. A lot.
Per protocol, we could go outside, but only in bulky outfits that simulated a kind of space-suit experience. These outfits were monstrosities, XXL neon-green hazmat suits, bought by Kim Binsted on sale from a government-surplus website. We’d set up our radio communication system (walkie-talkies) and our suit’s hydration system (an off-brand CamelBak), climb into the backs of the single-piece, heavy-duty plastic shells, Velcro up, wait in the “air lock” for five minutes (for light verisimilitude), and then venture outside. It was a process that usually required multiple people to get those of us leaving the habitat in and out of the suits, though Sian, who went out more than others for nearby photography projects, got very good at dressing solo.
The first space walk ever was done by Alexei Arkhipovich Leonov in 1965, who opened the hatch to his orbiting capsule, drifted out on an umbilical, declared the Earth “absolutely round,” and then struggled to get back inside. The space suit, due to either poor design or a malfunction, had overinflated and Leonov, suddenly too bloated, could not reenter his craft. The fix was to release some air, but the quick drop in air pressure to do so almost made Leonov pass out.
Though no one has died during an extravehicular activity, or EVA as NASA calls them, there have been close calls and dangerous failures, even recently. In 2013 Luca Parmitano’s helmet began filling with water from a leak in the unit within the space suit designed to separate moisture from his exhaled breath, almost drowning him in the vacuum of space. And in 2011, according to Kelly’s account in his book, a cosmonaut named Oleg Skripochka became untethered from the station during a space walk and actually floated away. The only thing that saved Skripochka, Kelly writes, was hitting a space-station antenna that sent him “tumbling back toward the station close enough to grab on to a handrail, saving his life.” And what if it hadn’t been so? Eventually, his life-support unit would’ve reached its useful limits, Kelly writes, and he’d lose consciousness from rising CO2 or oxygen deprivation, but hopefully not until mission control could patch him through to his family back on Earth.
In 1994, Neil Armstrong sent NASA a thank-you letter for his space suit. “It turned out to be the most widely photographed spacecraft in history,” he wrote. “That was no doubt due to the fact that it was so photogenic.” Though its true beauty, Armstrong added, was that it worked. Prodigious layers of choice material, cleverly assembled, is all that separates astronauts on EVAs from a harsh death by void.
Space suit as spacecraft, then. A house not much bigger than a body, to paraphrase the poet Francis Ponge, who was writing more generally about monuments and their scale: a space suit can be seen as a shell of a person’s own size that employs humanity’s “genius for adaptation and not disproportion.”
Armstrong’s human-size spaceship was designed and made by Playtex, the women’s bra manufacturer. It’s a riveting underdog story told in Nicholas de Monchaux’s book Spacesuit: Fashioning Apollo. The Playtex team, led by “a car mechanic and former television repairman” and made up of seamstresses and engineers, convinced NASA to let them send in a test suit for consideration, competing at their own expense against two other companies NASA had invited to the bid. With its twenty-one layers of neoprene rubber, metalized polyester films, and other materials, the Playtex suit outperformed the competition, proving it could protect astronauts from the dramatic temperature shifts in space—from 240 Fahrenheit in the sun to minus 280 Fahrenheit in the shade—as well as ultraviolet radiation and micrometeorites moving up to ten miles per second. Cosmic armor birthed by a bra company.
Some other reasons Playtex won the contract: precision stitching and a clever design that allowed enough flexibility so astronauts could move when the suit was fully pressurized. This flexibility came from bellows-like joints at the shoulders, elbows, hips, knees, and ankles, made of neoprene reinforced with nylon tricot—a fabric used in swimwear, gloves, and underwear. Steel aircraft cables acted as underwire, absorbing tension and helping the suit maintain its shape under pressure.
Our HI-SEAS suits were not nearly as engineered as real suits and certainly not as good looking, a source of discontent among some of the crew. These green monsters were bulky and cumbersome, which made them a fair simulation of the real thing, but even more frustrating, they didn’t actually fit the smaller crew members. The built-in faceplate was oversize and awkward. And when the cooling fans didn’t work as expected, the faceplates would fog, obstructing visibility. But more important, to the more media-oriented members of the crew, these suits did not look good when photographed. On a simulated mission, it’s not pictures of the crew sitting down for dinner—a dinner that could be anywhere—that people remember, it’s the space suits.
In the buildup to the start of HI-SEAS, we as a crew stayed in an apartment in Hilo, a town on the windward, east side of the Big Island. And in this apartment we spent many hours talking suit design with a local craftsperson named Jessica Cruzan. Binsted had enlisted her help in modifying the suits to fit us, to look less hazmat-y and more space suit-y and to field the critiques of the crewmembers who wanted something more flashy, less dumpy. Cruzan, who founded and runs Sew Da Kine, a successful business that makes handbags and wallets made of cork, did her best. And she did in fact improve the original suits so that they fit better, but ultimately, despairingly, some of the crew believed the suits still looked so different from any space suit that had come before that we would be mocked when the first photos of our mission hit the media.
A few weeks into the mission we still hadn’t posted photos from an EVA. Those first shots finally came when we received a new space-suit simulator to test out from the University of Maryland. It was a fluffy white getup with a separate dome-shaped helmet and looked very much the part. But it too had usability issues. The cooling system only cooled the torso, not the arms and legs, and it was heavy and bulky for smaller crewmembers. Still, this was the suit that we took the majority of those first pictures in. The green suits we kept as work suits for when we went on longer hikes or to do geological surveys. Photos of these eventually made it back to Earth and to my knowledge, they weren’t ridiculed. The drama of these suits on our mission, our human-size Earth-bound monuments to otherworldly exploration, drove home the fact for me that all non-space-suit space suits verge on the ridiculous if they’re worn by a person who’s not actually in or going to space. The suit is ever only a costume, highlighting the make-believe aspect of the experience. For me, these suits were a reminder of what was actual and what, regardless of how bad some of us wanted it, was not. They were always terrestrial vessels in spite of themselves.
The French philosopher Gaston Bachelard wrote that “faced with the bestial hostility of the storm and the hurricane, the house’s virtues of protection and resistance are transposed into human virtues. The house acquires the physical and moral energy of a human body. It braces itself to receive the downpour, it girds its loins. When forced to do so, it bends with the blast, confident that it will right itself again in time, while continuing to deny any temporary defeats.”
With four weeks left in the HI-SEAS mission, a hurricane approached.
Its name was Flossie, and there was concern, due to the position of the habitat on the side of a volcano, across from another large volcano, that there might be a wind tunnel effect, amplifying gusts to exceed the tolerance of the dome. Also the potential for mudslides and flooding. As a crew, we braced. Sian had come to Mars just off a thirteen-week internship with the Federal Emergency Management Agency as a sabbatical project. And Oleg, our crew health and safety officer, was a trained first responder. Simon also had emergency training.
A geodesic dome is one of the most stable and sound structures for its weight, thanks to the interlocking triangles that make up its surface. Still, we put most of our food and important equipment like the nose flute and the 3-D printer in the shipping container that we used for storage and as a tool shed, not knowing if the dome’s cover would hold. By our beds were bug out bags. Mine held notebooks, my laptop, phone, headlamp, and extra socks. I decided to leave my stack of unread New Yorkers behind.
On Mars winds can whip at up to one hundred miles per hour, which is hurricane speed on Earth. But because the atmosphere is only one percent as dense as Earth’s these gusts simply don’t punch. And while the wind is often dusty, producing storms that can cover the entire planet for weeks to months, the grains are fine. It’s less a sandblast and more a rusty cloud of smoke. On Earth, our storms are relatively short-lived, but they are powerful and can devastate lives and homes. Our worst-case scenario for Flossie would be to evacuate and hike out to a nearby military zone called the Pōhakuloa Training Area. Had this happened, it would have been the end of our mission.
The morning Flossie was to make landfall, I awoke to an unusual quiet. There were no winds, no thwapping of the habitat cover against the frame. All was still, and the air inside our dome felt strange, heavier maybe. The storm, we learned, tracked north and then west, just missing the Big Island. We unloaded the shipping container of the food and equipment we had put there only twenty-four hours before and proceeded with an otherwise ordinary day.
As I write this, recalling that storm, recalling other Martian memories, I sit in a studio apartment in Washington Heights in New York City. I live here now because I’ve gone back to school for an MFA. Technically, I suppose this makes me bicoastal. My name is also on a lease of the San Francisco rent-controlled apartment I share with Jill, who is still my wife, though after many conversations and a summer living together again between the first and second year of the writing program, trying to figure out what the shape of our relationship would be—the phrase we use over and over again—we’ve decided to separate.
Perhaps I am here because my brother died. And then my cat. And then the dog. And now my relationship of fourteen years. In the film The Hours, based on the novel by Michael Cunningham, the Virginia Woolf character announces that “someone has to die in order that the rest of us should value life more.” Life and value. Valium and vacuuming. Dust bunnies and love. Love and love. It’s possible.
We have different tolerances for going places and spending time apart. It takes Jill longer to settle into a home, and once she has, she doesn’t like to leave and start again, though it’s much more complicated than that. I think I have what’s called itchy feet. We’ve negotiated so much of our relationship around this issue in small and large ways, including while I was away on Mars. Now it’s time to try something else.
This apartment is my first space, singularly mine, since I was in my early twenties. It’s a luxury that many people don’t have, I know. And to “have” apartments in two of the most expensive cities in this country, frankly, is mind-boggling and somewhat embarrassing to me. In 2006, Jill and I lucked into a cheap one-bedroom in San Francisco’s Mission District and have clung to it ever since. We sublet it to a friend for two years while we lived in Nashville. That time was life-expanding in many ways—the writing community was so welcoming. We both learned so much. But the city of Nashville at large was a difficult place for me, in particular, to be. For my perceivable queerness, I experienced everything from stares and sneers to outright confrontation. I wouldn’t have wanted to stay there. While we were gone, San Francisco rents soared, but because of our apartment, we could land there again.
The low rent, I believe, is one of the main reasons Jill and I became the writers we are and are continually trying to become. It’s allowed us to make job decisions that gave us time over money. These include my four months on Mars, which did pay, but only an after-the-fact $5,500. It allowed her to be an adjunct professor, to do some editing on the side, and to play tennis at the nearby public courts within a strange and beautiful community of tennis players that has inspired much of her current work. And it allowed me to move to New York, to find a place of my own, to work on these essays, and to become again another kind of writer.
In his Poetics of Space, Bachelard quotes the French historian Jules Michelet on nests, as in the kind made by birds: “Michelet suggests a house built by and for the body, taking form from the inside, like a shell, in an intimacy that works physically. ‘On the inside,’ he says, ‘the instrument that prescribes a circular form for the nest is nothing else but the body of the bird. It is by constantly turning round and round and pressing back the walls on every side, that it succeeds in forming this circle.’”
I think not just of a bird body pressing against a space, but of how psyches and behaviors imprint onto the places where we live as well. In this studio, I prudently, frugally chose all of the objects that surround me, as if they are myself by extension. The place has a certain “Kateness” to it, a friend once said: considerations that are evidently and obviously mine when observed by others. A sensibility manifests in space, my behavior molds a dwelling as I sink my body into this bed, that couch, the chair at the desk upon which I rest my elbows and forearms. Inside this limited square footage, I walk the same limited paths over and over. Here I’ve painted pictures, collected postcards, broadsides, and calendars, taken Polaroids, and hung them all on my wall. Books surround me, there are books on every surface. I press myself into the materiality of the apartment in a way that is wholly, exclusively myself.
Bachelard continues, “Michelet goes on: ‘The house is the bird’s very person; it is its form and its most immediate effort, I shall even say, its suffering. The result is only obtained by constantly repeated pressure of the breast. There is not one of these blades of grass that, in order to make it curve and hold the curve, has not been pressed on countless times by the bird’s breast, its heart, surely with difficulty in breathing, perhaps even, with palpitations.’”
I contrast my New York apartment, which is fairly uncluttered, with my aging parents’ house in Kansas, a nest of a different sort. They’ve lived in it for decades. The walls are closing in, made of objects typical of any cluttered home: stacks of mail, magazines, excessive kitchen appliances, items to be returned to stores, items to sell on eBay, containers within containers for everything and nothing. And when I asked why there were so many wicker duck baskets, my mother responded proudly that three or more of anything makes a collection.
I go back and forth on this. Their house is not easy to navigate. A guest might need to move a box of quilting supplies, for instance, to find a soft place to sit. Might there be some benefit to this? The architecture of the avant-garde artist couple Madeline Gins and Arakawa, specifically the Bioscleave House (Lifespan Extending Villa) completed in 2008 in East Hampton, New York, is related to the idea that discomfort in this world staves off death—that the chaos of a bumpy, slanted floor or the “poorly” placed light switch will make you more aware of your surroundings and therefore more alive. It’s true that environments that are too predictable feel sterile and can lead to boredom and lethargy. And an easy way to feel young is to experience something new, to travel, to see a thing with fresh eyes. But I wonder. Isn’t it true that most of us can habituate to anything? Isn’t it our nature to minimize effort and discomfort?
My parents’ movements have constricted as they’ve gotten older, for health reasons, but also perhaps because of their environment. There can be no doubt that their nest restricts them. But again, here I’m conflicted. Personally, I really do appreciate small spaces. I might even get a little nervous in too-large rooms. I think about how shrinking a space makes it feel safer. When you, the bird, need only spin in place to press your breast into your own clutter, to smooth the walls with your own self, you can believe nothing will sneak up on you. Large spaces become vast, become infinite until we find ourselves edging toward an abyss and with it, the accompanying terror. Anne Carson speaks of a domesticated abyss, which is, in effect, an abyss recognized and then restricted in some way so as not to let it get the better of us. What do we need from our nests to feel safe? To forget the abyss and how dangerous all this is, how dangerous and precarious it is to have a body and to move through space, how unlikely and fleeting it actually is to be alive at all.
There’s a very special room in the space station called the cupola, a room full of windows. It’s where astronauts pose for photo ops, wax philosophic, soak up terrestrial sights, and bask in Earth-reflected sunlight. It’s a spacious respite from the rest of the station, which can be, and if you’ve seen the pictures you know, quite cluttered with equipment, supplies, and bags of refuse.
In the cupola, you can float above it all, literally, above the planet where the entirety of human history has played out, where, Carl Sagan wrote, “everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives.” Sagan was speaking of the “Pale Blue Dot” as photographed from the Voyager 1 spacecraft in 1990 at a vantage of 4 billion miles, an on-its-way-out-of-the-solar-system point of view. No real need to compare and contrast, though, any extraterrestrial look, even two hundred miles up, can be a perspective shifter.
In one of the cupola’s windows, there’s a divot. Created by a spec of space matter, either a micrometeorite or a particle of space junk made from colliding satellites, this divot is a reminder that low-earth orbit harbors danger. There are more than a hundred million tiny pieces of space junk zipping around the planet, sometimes crossing paths with the space station. To protect against it, the station employs a patchwork of shields made of Kevlar and placed at a distance beyond the exterior walls because, if large enough, one of these space bullets could rip a hole inside the space station, which, depending on where and what size, would be bad to catastrophic.
Ground control monitors the bigger stuff, junk that’s larger than 1.5 centimeters in diameter. With enough warning, say six hours, astronauts can engage the station’s thrusters and slip out of a charging satellite’s path. But sometimes there isn’t enough warning.
During Kelly’s yearlong stay, a defunct satellite on a path to fly within a mile of the station was detected too late. The discovery of this imminent object triggered a set of procedures. Among them, Kelly had to close all eighteen hatches on the U.S. side of the space station, which takes about two hours. The thinking is that if the satellite hits one module, the impact would only decompress the damaged module and the rest of the station could be saved. In the middle of this battening, mission control phoned up to remind Kelly and the cosmonaut Gennady Padalka that they had a previously scheduled public relations event—to talk to a Louisville, Kentucky, television station about what it’s like to float in low gravity and the Kentucky Derby.
Kelly, who reads to me as the quintessential grumpy space robot, complied, but didn’t seem happy about it. Understandably. He was being asked to close hatches, a chore that, probabilistically, was a waste of time. The two most likely scenarios were that the junk would miss the station entirely or that it would hit the station and completely obliterate it. This particular satellite was clocked at 17,500 miles per hour, coming in at the opposite direction of the station, which is also traveling at 17,500 miles per hour—a collision that would release the same energy as a nuclear bomb. And then, in the middle of this most likely pointless task, Kelly had to spin somersaults and answer questions about horse racing, all the while, there was a non-zero chance that his annihilation was less than an hour away. This section of Kelly’s book contains more instances of the word “fuck” than any other.
Interview complete, hatches finally secured, Kelly, Padalka, and Mikhail Kornienko loaded themselves into the Soyuz spacecraft docked at the station—a kind of emergency life raft. As Kelly tells it, the three of them looked out the windows, waiting and watching even though there was no light, no earthshine. They sat in darkness and waited. They waited for the speeding satellite, which wouldn’t be visible even if there were light because it would be moving so fast.
Of course, the satellite missed. “Moscow, are we still waiting?” Padalka asked after a while. “Gennady Ivanovich, that’s it,” Moscow mission control responded. “The moment has passed. It is safe; you can go back to work now.”
Kelly, spending the next two hours reopening the hatches, reflects on the near miss. “Had it in fact hit us, we probably wouldn’t even have known it,” he writes. “Misha, Gennady, and I would have gone from grumbling to one another in our cold Soyuz to being blasted in a million directions as diffused atoms, all in the space of a millisecond. Our neurological systems would not even have had time to process the incoming data into conscious thought … I don’t know whether this comforts me or disturbs me.”
Space-junk collisions are mostly a problem in low-earth orbit. Once a craft is on its way to the moon or Mars, both of which NASA considers “deep space,” the real threat comes from radiation, either cosmic rays from deep space or solar flare-ups. A blast from a solar event could result in short-term radiation sickness or long-term increased risk of cancer.
NASA’s new spacecraft designed for jaunts to the moon and Mars is called Orion, and it has a compartment, like a storm shelter, where astronauts can huddle during such events, surrounding themselves with bags of supplies like food and water that can impede the flow of charged particles.
Once on Mars, astronauts are still vulnerable to radiation. Where Earth has a robust magnetic field that surrounds it, produced by its molten metal core and useful for deflecting the majority of dangerous incoming charged particles, Mars does not. An astronaut on Mars is almost as exposed to radiation as they would be in their spaceship. Any kind of Martian habitat would need to incorporate radiation shielding, but the reality is this shielding can be extremely heavy and might not be worth transporting. Rather, it could make more sense to 3-D print a habitat out of liquified regolith or set one up in a Martian cave—and there are many of them to choose from. Once upon a time, Mars was a living, breathing planet with active and massive volcanoes. Just like on Earth, these Mars volcanoes would erupt, lava would flow, and the top of the lava would cool and harden into a crust as the lava below would course out into another region, leaving behind a so-called lava tube. As on Earth, the top crust would crumble, providing an entrance to the lava tube, a cave into which a habitat, perhaps inflatable, might be nestled, where Martian rock is the radiation shield.
As a person who lives in both San Francisco and New York, I think of the views. There would, unfortunately, be none from inside this cave-based habitat, no direct windows to the outside. “The house shelters day-dreaming, the house protects the dreamer, the house allows one to dream in peace,” writes Bachelard. I wonder how often those on Mars will dream of Mars and how often they will dream of Earth.