If we're going to send humans to Mars, we're going to need a new spacesuit. And that requires decades of inventing and testing—plus danger and hope.

Mars is a hostile neighbour. Its average temperature hovers around -60 °C, although it can dip as low as -125 °C in wintertime. The faint atmosphere—100 times thinner than Earth’s—offers little protection from cosmic rays and solar radiation, but just enough of a shell to create bad weather: dust storms that last for months and envelop the entire planet. And the red soil itself is quite possibly toxic to humans, shot through with carcinogens and corrosive, highly chlorinated salts that might burn unprotected skin or even eat away at spacesuits. Life may well have existed there billions of years ago, when the Martian climate was more temperate and its surface covered by lakes and oceans. If it persists now, it would only be in the form of microbes buried deep in the dirt, or locked under the icy poles.

Yet visiting Mars has been the stuff of dreams—in science fact and fiction—for more than a century. We’ve launched 40 spacecraft toward the red planet since the early 1960s, first buzzing by, then orbiting, then warily touching down to explore with instrument-stuffed probes and, more lately, remote-controlled rovers. Manned missions—the next logical step—have been confidently forecasted for 50 years. But it won’t be until next May that a human will finally take the first tentative steps in the staggering 53-million-km journey to our unwelcoming sister world. As rescuers stand by, all of the air will be pumped out of Vacuum Chamber B at NASA’s Johnson Space Center (JSC) in Houston. And inside its thick metal walls, behind a giant metal hatch, a member of the team that has built the agency’s new Z2 planetary exploration spacesuit will find out first-hand whether their prototype will pass the fundamental test of keeping a person alive in a virtually airless environment such as Mars’s.

“The significance of what we’re doing with Z2 is easy to miss,” says Amy Ross, the lead designer and head of NASA’s Advanced Space Suit Technology Development Lab. “Just putting a pressure garment in a vacuum chamber with a little squishy person inside is a big deal. We’re talking about a place that can kill you in seconds, if you’re not careful.”

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Accidents are not an idle concern. During a test of an early version of the moon suit inside a different JSC chamber back in 1965, a technician named Jim Le Blanc lost pressure in his suit when an air-supply hose became disconnected. His last memory before blacking out was his saliva boiling on his tongue. Le Blanc survived because a rescuer, wearing an oxygen mask, was stationed in a partially pressurized antechamber and was able to open the door within 25 seconds.

It will take closer to 40 seconds to re-pressurize the much larger Chamber B and bring in help if something goes wrong during the Z2 tests. That’s still fast enough to avoid disaster, reckons the team of 60 doctors, engineers, technicians and program managers who have spent six months preparing for every imaginable contingency. “At NASA, we build from our mistakes and failures,” says Joe Gensler, the engineer in charge of the tests. “It costs money and takes time, but it’s worth it.”

Even the most stringent precautions can’t guarantee safety, however. That’s the tragic lesson the U.S. space program first absorbed from the explosion of the shuttle Challenger in 1986, then relearned 17 years later with the Columbia disaster. In both cases, it was tried-and-true technologies that failed and sparked catastrophe. For no matter how much thought NASA’s big brains put into it, space flight exposes new risks all the time.

Protective suits are not immune to that dynamic. In July 2013, during a routine walk outside the International Space Station (ISS), Italian astronaut Luca Parmitano felt water on the back of his head. Mission control ordered him back inside almost immediately, but, by the time he reached the airlock, more than 1.5 litres had filled his helmet, covering his eyes, ears and nose, and threatening to drown him, some 400 km above the closest body of water. An investigation later determined the problem was caused by a clogged filter in a liquid cooling garment the astronauts wear. Parts and procedures were modified, but, in late February, U.S. astronaut Terry Virts came back inside after a spacewalk and found a smaller, but no less worrying, amount of water in his helmet.

The suits currently in use on the ISS are modified versions of the one constructed for the first shuttle missions in the early 1980s, based on even earlier Apollo moon program technology. Originally designed to be used for a couple of weeks in space, then returned to Earth for refurbishment, they now spend up to six years in orbit, serviced on the fly and used in dozens of walks.

Jeff Hanley, director of NASA’s extravehicular-activity (EVA for short) management office, calls them “venerable performers,” but says the recent problems illustrate that a new suit is long overdue. “We nearly killed somebody. How close we came is not widely appreciated. We were within minutes.”

If the United States is going to forge ahead with its current plan for a crewed flight of the deep-space Orion capsule in 2021, followed by a test mission to an asteroid later in the 2020s, and then a Mars landing around 2035, creating a reliable interplanetary spacesuit is Job 1. After all, walking on the red planet would be the whole point of a 500-day round trip that will cost billions. It’s been 43 years since Apollo 17, the last time a human set foot on an alien surface—and longer still since anyone at NASA built and tested a garment to withstand the rigours and risks of ground exploration. “The guys who designed those suits are no longer in the program and, in many cases, are no longer with us on this planet,” says Hanley. “We ain’t been there, and we ain’t done that.” Our dreams of Mars are as powerful as ever. But, before anyone straps into a rocket and blasts off, there’s an awfully big mountain left to scale on Earth.

Amy Ross grew up at the Johnson Space Center. Her father, Jerry Ross, is a NASA legend, having flown on seven shuttle missions, and has performed nine spacewalks—both program records. When her mother needed a break on weekends, Jerry would bring Amy and her brother to the office and let them play with a computer simulation of the shuttle waste-management system. Many happy childhood Saturdays were spent flushing pretend toilets out into space.

Ross first started working at NASA as a summer co-op student while studying mechanical engineering at Purdue University. Spacesuits turned out to be the thing that interested her most, hitting close to home. She joined the development lab full-time in 1992, and became the project lead in 2011.

Building a spacesuit is much more than an engineering problem. It requires a designer to consider faraway environments—and human nature, too. “I know a little bit about all kinds of things,” says Ross, “the planet Mars and its weather and surface. I know about Mars dirt. I know about how the lungs work and how blood circulates in the body. I know about psychology: You put someone in a spacesuit and you can see all kinds of different emotions go through them.”

The Z2 suit is still being fabricated by NASA’s various subcontractors, but Ross has an earlier prototype on display in her cluttered, windowless lab at the JSC. The biggest changes are the titanium bearings at the shoulder, waist, hips and ankles, which promise an almost natural—or, at least, less Frankenstein’s monster-esque—range of motion. Another difference is a rear-entry hatch that will allow astronauts to slide easily in and out of the whole garment, as opposed to the current suits, which require them to put the pants on, then pull the rigid torso over their heads like some sort of steel sweater. The Z2 will also be topped with a dome-like helmet that offers a wider range of vision, and will have illuminated neon-green strips on the chest—a sci-fi design element that NASA put to a vote on the Internet. An artist’s rendering makes it look a lot more Buzz Lightyear than Neil Armstrong.

But the Z2 prototype will be far from a finished product. Ross continues to experiment with various composites for the shell, and still isn’t sure how many layers and what type of fabrics will be required to protect against the peculiar hazards of Mars. (The current orbit suits use 14 different layers to keep the air in, insulate, and guard against radiation, rips, even micro-meteoroids.) The Curiosity rover, which landed on the red planet in August 2012, has been taking radiation readings to help with the decision. And the next NASA rover, scheduled to launch in 2020, will probe the chemical composition of the soil and expose various suit materials to the weather and radiation to see how they hold up.

The current vision is for the Mars suit to be pressurized at 8.3 lb. per square inch (psi), versus the 4.3 psi suits used on the space station. The advantage would be that astronauts would no longer have to do a scuba-type “pre-breathe” to acclimatize to the low pressure—on Earth, air pressure at sea level is 14.7 psi—thus allowing them to quickly come and go from the lander. But the downside is that the new suits will be stiffer, which might undermine the enhancements designers had made to aid mobility. Then there’s the question of their weight. The Z2 tips the scales at about 136 kg, about the same as the station suits. That’s not a big deal in the microgravity of orbit, but it may be a problem on Mars (which has about a third of Earth’s gravity), because astronauts may suffer considerable muscle loss during their weightless, 200-plus-day trips to get there. Ross hopes eventually to test the prototype out on an astronaut who has just returned from an extended period in orbit to see how he or she copes with the load.

But, for the initial vacuum-chamber tests, in which volunteers walk at various speeds on a treadmill to check the Z2’s mobility, fit and comfort, NASA will be taking no chances. Engineers have rigged up a safety harness attached to the ceiling to prevent a small stumble from turning into a potentially fatal, visor-cracking face plant.

For a while, NASA engineers toyed with the idea of putting all life-support functions inside the suit itself, but, fearing the addition of even more bulk, returned to the backpack-style units they have been using since Apollo days. The separate design team working on that primary life support system—or PLSS, as everyone calls it—are also contending with some unique Martian challenges, such as a carbon-dioxide-rich atmosphere that might complicate the job of venting what astronauts exhale inside the suit. The vast distance from Earth—it can take anywhere from three to 22 minutes to send a message one-way between the two planets, depending on where they are in their orbits—means all functions will need fail-safe backups, and must allow for easy repair or replacement. Known problems such as the current water leaks in the station suits will be designed out of existence. “They’re trying to make sure that the water loop can spit out chicken soup and not worry,” jokes Ross.

Some hoped-for innovations for the Z2 such as heads-up, in-helmet display, and self-cleaning interior fabrics—spacesuits have a tendency to develop a hockey-equipment-like funk—are still on the drawing board. Others, such as an electronic mission checklist on the cuff, and automatically adjusting temperature control, have already been rejected. (The former looked as if it would be too hard to operate with thick gloves. The latter was impractical, because each astronaut has a different idea of comfort.)

Ross says her suit won’t be fully realized until astronauts have worn and worked it in test chambers, swimming pools, and space for thousands of hours—but that it’s time to move forward. “An engineer will mess with a toaster for years, if you let him,” she says.

Ross’s biggest design accomplishment so far in her 20-plus years at NASA was certifying a new glove for the current station suits. There were 19 different versions of the gauntlet, and endless debates over things as minute as the stitching and seam allowances. The whole process took more than a decade. And her dad was the first to wear them in space.

NASA calls it the Neutral Buoyancy Laboratory, but you would know it as a pool. Albeit an unusually large one—62 m long, 31 m wide, and 12 m deep—containing 2.3 million litres of water, heated to precisely 32° C, and with an almost full-scale mock-up of the International Space Station sitting on the bottom.

It’s late afternoon, and astronauts Shane Kimbrough of the U.S. and Thomas Pesquet of France are on their way to the surface after a six-hour training session in their station suits. Safety divers guide them onto a yellow metal platform and tie straps around them before a crane winches them upward. It takes a few more minutes to release them from their protective shells. Afterward, standing on the pool deck in their long-underwear-style cooling garments, they shake their arms and flex their hands to get the blood flowing again.

Pesquet, a 37-year-old who will spend six months in orbit starting in November 2016, recalls the first time he put on a spacesuit. “It felt like being in a coffin with a window,” he says. The hard torso and shoulders restrict your arm range to a couple of square feet—about the dimensions of a smallish TV—directly in front of you. (Shoulder injuries are a common hazard.) And dealing with anything to the side, or rear, requires turning the entire outfit in a jerky, stop-and-go manoeuvre that is pretty much the antithesis of graceful.

But the suit is hardest on your hands, explains Kimbrough, a lanky 47-year-old army colonel, with two spacewalks already on his resumé. Even at 4.3 psi, the pressure relentlessly forces one’s hands open, and doing things like gripping a tool requires constant effort. “The first day I wore one, I got home and I couldn’t work the doorknob,” he says. Astronauts try to train for the strain by going to the gym and carrying heavy kettle bells with their fingertips, but nothing really helps. “It’s a long fight,” says Kimbrough.

It used to be worse, says Jerry Ross, Amy’s father. The pressure bladders in the old-style gloves crushed fingernails, created hot spots on the palms and rubbed against the inside of the fingers—so badly, astronauts lost feeling in parts of their hands after only a couple of hours. Following his first two spacewalks in 1985, the numbness persisted for weeks after he returned to Earth. “It was to the point that I was starting to worry that maybe I’d done some permanent damage.”

Amy’s Phase VI glove solved most of those problems, but the fix didn’t make the rest of the station suits any less cumbersome.

From Ross’s description, the four-hour-plus process of getting into one to head out into space sounds like a claustrophobe’s nightmare. “Imagine putting on about four pairs of very thick pants that make your legs stiff and hard to move. And putting on a couple heavy sweaters and a thick wool coat that makes it very hard to move your shoulders and arms. Then pull on very heavy, thick, leather, woolly gloves, and maybe a football helmet with a big visor on it,” he says. Waiting inside the airlock, you can barely move. “You feel like a bull in a china shop.” Outside, floating free in next-to-zero gravity, getting around is easy, requiring only the lightest push. Everything else remains a struggle, due to the limits the suit places on touch, sight and mobility.

Amy hasn’t asked for his advice on the Z2, but the now-retired Ross can still rattle off the astronaut wish list. “Give me the lightest, most flexible, reliable and safest suit you can,” he says, “and, if possible, give me something that’s comfortable to wear.”

The Apollo suits were custom-made for each astronaut, while the station suits come in medium, large and extra-large. At a cost of $5 million each, the Z2s are being built to be worn by multiple people on multiple missions, although new technology is being harnessed to try to make them fit better. Amy Ross and her team used motion-capture sensors and body scans in the design phase, and 3D printing is enabling them to check out, as they go, the look and feel of various tweaks and adjustments to parts like the torso and briefs. For example, the crotch was recast after astronauts complained that the prototype was too roomy. “You make assumptions about what’s comfortable, and sometimes they turn out to be wrong,” says Ross.

What really stands between NASA and a fully functioning interplanetary suit isn’t the design challenges, however, it’s the mandate and money. Presidents and Congress like to talk about going to Mars, but they aren’t so keen to pay the big bills for a project that might not come to fruition for decades. Back in 2004, George W. Bush announced a renewed push into space, starting with another Moon landing by 2020, then a mission to the red planet. But, five years later, in the midst of the global recession, a blue-chip committee convened by President Barack Obama determined that NASA’s manned-flight Constellation program was so over-budget and behind schedule that it couldn’t meet its goals. Obama cancelled all its funding in 2010, and announced a new plan to get to Mars, a little more cheaply, and in not quite such a hurry.

NASA remains a huge organization. Its projected budget for the 2016 financial year is $18.5 billion—a half-billion-dollar increase. But in inflation-adjusted terms, its funding has been shrinking for decades.

Even the Johnson Space Center is showing its age. Building 1, its headquarters, feels like a crumbling high school, right down to the stained carpets, masking-tape-yellow paint on the walls, and battered early-’80s-vintage office furniture. Jeff Hanley knows all about budget pressures. He was the head of the Constellation program until the spring of 2010, when he was suddenly reassigned after trying to start a rearguard campaign against Obama’s cuts. Now in charge of the much smaller and less sexy EVA office, he is fighting to keep the development of the Z2 on course, among dozens of other NASA programs and priorities. “The spacesuit is just a much diminished version of the conundrum we faced with the shuttle,” he says, seated behind a worn table in a corner office that is stuffed with Star Trek memorabilia. “There weren’t resources available to continue to fly the shuttle and develop something new.”

The challenge for Hanley, Ross and others has been to keep making progress, despite the ever-shifting big-picture vision. Right now, Hanley feels they are three to five years away from a finished project, “once a true commitment is made.”

There’s a possibility it won’t even be NASA that makes that leap. Elon Musk, the founder of Space X, a private company that is already launching cargo shuttles to the ISS and has planned to start ferrying astronauts by 2017 (at least, until one of its Falcon 9 rockets exploded in June), has said he intends to unveil a Mars ship and suit by the end of this year. His goal is to land the first human on the red planet by 2026, and establish a colony of 80,000 by 2040. That would necessitate transforming the spacesuit business from haute couture—NASA has just a dozen that are flight-worthy—to Wal-Mart, in short order.

Amy Ross laughs when asked about such a possibility. “It’s a lot easier to say it than to do it,” she says. Her focus is on the Z2 vacuum tests—and not killing one of her colleagues. After that will come endless hours of submersion in the Neutral Buoyancy Lab pool, then tweaks and redesigns. She figures it will be the Z3, or Z3.5 that eventually makes it into space for more testing on the ISS. At age 42, with maybe another 20 years to go on the job, she’s not even convinced she’ll be around to see someone clad in her handiwork take humankind’s first steps on an alien world. If that’s frustrating, she won’t admit to it. “We are going to Mars,” she says, “but we don’t know when. You have to have a long-range view.” Many small steps in advance of the next giant leap.

Get to know the great unknowable. Read Maclean’s special Space issue, on newsstands this week and on Next Issue, Apple Newsstand and Google Play now.