When astronaut Eugene Cernan stepped from the moon’s surface into his spacecraft in December 1972, he was aware it was the end of an era. His mission, Apollo 17, was the last of the Apollos.
“Take your final look at the valley of Taurus-Littrow, except from orbit,” Cernan said of the view before the craft lifted off. “We’re on our way, Houston!”
And with that, the last person to walk on the moon returned to Earth. No other boots have touched lunar soil in the 50 years since then.
Now, NASA is preparing to go back, and China is on its way too. On November 16, the U.S. Artemis I mission launched to bring the first crew-ready space capsule to the vicinity of the moon since Cernan and his two crewmates left half a century ago.
That spacecraft isn’t carrying any astronauts; the mission was designed to check technology and other systems that will eventually take people to the moon, on Artemis III, no sooner than 2025. This time, NASA says, the intention is to stay longer, to learn how to live on the moon and eventually send people to Mars.
The obvious next question is, who gets to go?
Thanks to social, political and scientific changes over the last 50 years, today’s astronauts are not like the astronauts of the past. They are more diverse in sex, race and field of expertise. The next set of people to walk on the moon will face different challenges and require different skills, temperaments and support systems than the Apollo crews.
And some groups are thinking about how to include people with disabilities in the spacefaring future. Preparing for a more permanent human presence in space will require rethinking the right stuff. Future lunar crews may reflect our lives on Earth more faithfully, making space for everyone.
Becoming an astronaut
NASA has declared that upcoming missions to the moon will include a woman and a person of color, setting two firsts for lunar astronauts.
The next visitors to the moon haven’t been selected yet. But there are only about 50 people to choose from. The 43 active astronauts and 10 astronaut candidates, who are still in training, come from a variety of backgrounds. The list includes medical doctors, military pilots, geologists, microbiologists, engineers and others. Of NASA’s active astronauts, about 37 percent are women.
“The astronaut corps is, of course, NASA’s most visible workforce,” says Lori Garver, who was NASA’s deputy administrator from 2009 to 2013. “Because of that, NASA has, I think, a responsibility to have an astronaut corps that reflects the nation.”
Modern astronauts are already different from those of Apollo. For its first class of astronauts in 1959, NASA recruited military fighter pilots shorter than 5 feet, 11 inches (because of the tight space in the Mercury space capsule). At the time, all military test pilots were white men, so all astronauts were too.
NASA recruited its first class of “scientist-astronauts” in 1964. The move drew criticism from pilots. In an interview, Cernan — who shared his spot on Apollo 17 with the only geologist to walk on the moon, Harrison Schmitt — called science “a parasite” on the moon program. “Science is not the reason we learned to fly,” he griped. Cernan later referred to Schmitt as “Dr. Rock” and worried that he wouldn’t be able to get out of a tough spot on his own.
But according to NASA’s mission report, Apollo 17 was “the most productive and trouble-free manned mission.” It “demonstrated the practicality of training scientists to become qualified astronauts.”
Today, 42 percent of NASA’s active astronauts have a research science or medicine background, in fields ranging from oceanography to physics.
Counterintuitively, though, NASA’s definition of “astronaut” doesn’t require going to space. Once you’ve made it through the strenuous and selective application and training process, you’re a member of the astronaut corps, whether you leave Earth or not.
The first step in applying to be an astronaut is “unnervingly underwhelming,” says geobiologist Zena Cardman, who joined the astronaut corps in 2017 but has not yet been to space. “You submit a very short resume to USAJobs.gov, and then you wait for a long time,” she says. (Full disclosure: I applied to the astronaut program myself in 2012. I kept the rejection postcard for years.)
The minimum requirements for applying are being a U.S. citizen, having a master’s degree in engineering, biological science, physical science or math, and two years of professional experience, including teaching or graduate school. Pilots can substitute the two years of experience with 1,000 hours of jet-flying experience. Candidates who make it through that first round travel to Houston for a two-round interview process.
“What we’re looking for in these first few Artemis missions … first and foremost, is technical expertise,” astronaut Reid Wiseman, chief of NASA’s Astronaut Office, said in a news briefing on August 5. A lot of those desired skills revolve around acquiring resources to support long stays.
Artemis III plans to send people to the lunar south pole, which could be a reasonable place to put a long-term base. It has regions that will be in sunlight for the entire 6.5-day mission. The light will help generate energy from solar power. And it has regions in permanent shadow that host pockets of water ice, which could be used for water and fuel for human settlements.
The possibility of finding and using resources on the moon is part of why science backgrounds, especially in geology, are now more important for astronauts. But in the astronaut corps, everyone does everything, Cardman says. Her background is in geology and microbiology. She’s done fieldwork in Antarctica, the Arctic, underground caves and on ocean research vessels. Space “seemed like the ultimate fieldwork endeavor,” she says.
To round out her skills, she’s getting trained in engineering and aviation, and her test pilot colleagues are learning geoscience. “We will have roles, but we won’t be siloed,” she says.
Beyond technical skill, the next most important characteristic NASA looks for is: “Are you a team player?” Wiseman says. Working together was important on the Apollo missions. But those missions lasted 12 days at most, with three days tops on the lunar surface. Astronauts on a weeks-long Artemis mission to the moon or a years-long mission to Mars will need to survive in stressful, challenging, isolated environments (SN: 11/29/14, p. 22). Getting along becomes crucial to staying alive.
That explains why the interview process includes teamwork exercises and group dynamic activities to simulate the kinds of situations astronauts would find themselves in, Cardman says.
The interview also involves medical screening. The details are not public, but “they really go quite in depth,” Cardman says. There’s no official requirement for any particular body type or standards for physical fitness, like running a mile in a certain time or doing a certain number of pull-ups. “It’s more functional,” she says. As long as you can meet the mental and physical demands of a spacewalk, it doesn’t matter how you get in shape. Cardman’s exercise of choice is powerlifting.
Ultimately, there are thousands more applicants than there are openings for astronaut jobs. “The final selection is somewhat subjective,” Garver says. “So I think it’s absolutely appropriate that you look at the demographic along with the qualifications.”
Take it to the limit
There’s one other medical requirement for the next people to walk on the moon: They can’t have already spent too much time in space.
Over time, exposure to the harmful charged particles that zip around space can increase a person’s risk of developing cancer. For astronauts’ safety, NASA limits the amount of radiation an astronaut can absorb over their career. (SN: 7/4/20 & 7/18/20, p. 18).
From 1995 until 2021, those bounds were dependent on an astronaut’s age and sex. The limit was the amount of radiation that correlates with a 3 percent risk of dying from cancer caused by radiation exposure. But because women were considered to have higher risks of dying from radiation-related cancers, that limit grounded female astronauts earlier than males.
Effectively, women were allowed about 150 millisieverts of radiation in their careers, while men were allowed closer to 800 millisieverts, says emergency medicine physician and aerospace engineer Erik Antonsen of Baylor College of Medicine in Houston.
“It was a consequence of the way we were calculating risk that women were being limited much earlier in their career and could not fly as much as men,” Antonsen says. “We had to dive deep into that stuff, come back up for air and say, hey man, there’s not justification for this stuff. And it’s causing discrimination against females.”
Antonsen notes that no openly transgender astronauts have flown, but he can’t think of any medical issues that would hold them back.
In 2021, the National Academies of Sciences, Engineering and Medicine released a report urging NASA to change the limit to 600 millisieverts of radiation over a career for everyone, regardless of sex or age. That amounts to about 400 days in orbit around the moon or 680 days on the lunar surface, some of the time in a habitat, for an astronaut with no other spaceflight exposures.
NASA, the German Aerospace Center and the Israel Space Agency are flying a pair of dummies on Artemis I to test a radiation protection vest for female astronauts, which might help reduce radiation risks further if worn on future missions.
That could all be good news for Cardman. She and her cohort, who are beginning to fly missions to the International Space Station, are likely candidates for Artemis III. Cardman herself could be the first woman on the moon.
She’s modest about it. “I would be thrilled to go to the moon, of course,” she says. “Depending on the timeline, who knows. But it’s pretty exciting to know I work with the people who will be the first ones setting foot on the moon in half a century.”
The new right stuff
Even though there are no official astronaut health standards, NASA does end up selecting “the healthiest damn people to fly,” Antonsen says.
Commercial spaceflight is expanding the pool of people who get to go to space. Companies like SpaceX, which is building the moon lander for Artemis III, and Blue Origin are already sending paying customers on space joyrides. These companies have different goals, incentives and risk tolerances than NASA does.
“The beautiful thing about this is, the goal is eventually to send just people,” Antonsen says. “It’s changing. And it should change.”
SpaceX would not comment on how it chooses who it sends to space. But Antonsen speculates that some companies’ only criteria for their customers will be “making sure they can walk up the stairs to get to the vehicle.”
And even that might not be the final barrier for long. Some organizations are investigating how disabled people can live and work in space.
“Disability inclusion affects how we design our spacecraft,” says AJ Link, communications director of the nonprofit advocacy group AstroAccess. “If we can make space accessible, we can make any space accessible.”
By organizing flights for disabled people on zero gravity aircraft, AstroAccess aims to show that disabled people have strengths that could be useful in space. In October 2021, 12 people with various disabilities took a parabolic flight, in which the plane took a repeating upward and downward trajectory to give the passengers inside a few minutes of weightlessness.
“My personal, emotional conclusion was, it was wicked fun,” says Sheri Wells-Jensen, a linguist at Bowling Green State University in Ohio. Wells-Jensen, who is blind, was one of the people on that flight. She plans to try it again in December, on the anniversary of Apollo 17’s departure from the moon, despite describing herself as a “big chicken.”
“I’m not a thrill seeker. I don’t even like roller coasters,” she says. But in zero g, she was “surprised by how not terrified” she was.
She was also surprised at how useless her normal instincts were. In simulated lunar gravity, a tiny hop sent her flying to conk her head on the ceiling. The plane was so noisy that her normal ways of orienting by sound didn’t work. She felt like there was no up or down. “I’m damn well oriented on Earth, but boy, there were several moments there where I had nothing,” she says.
Learning how disabled people behave on spaceflights will help all astronauts in the future, regardless of disability, Wells-Jensen says.
“Space is a profoundly disabling environment. It’s always trying to kill you,” Wells-Jensen says. What happens if an astronaut loses their vision, whether temporarily or permanently, on the way to Mars? Or if the spacecraft lights go off, or smoke makes it hard to see? Designing a spacecraft to be used by blind people, she says, will help all astronauts navigate those situations.
Similarly, if an astronaut loses use of their legs, knowing how people with amputations or limb deficiencies navigate a spacecraft will give them options. “For able-bodied people who acquire a disability in space, we’re not just going to send them home,” Wells-Jensen says. “How do we make sure they’re safe and can still do their jobs?”
Wells-Jensen hopes that sending disabled people on zero-g flights will raise awareness of how capable they are as well. “A disabled person could take a suborbital flight tomorrow,” she says. “I think at this point, the limiting factor is cultural, rather than technological.”
The European Space Agency is also recruiting disabled astronauts, with physical characteristics such as limb deficiencies or short stature that would normally disqualify them. These “parastronauts” will help study the kinds of adaptations needed for disabled people to fly in space. In November, ESA named its first parastronaut: John McFall, a British paralympic sprinter and orthopedist, whose right leg was amputated after a motorcycle accident when he was 19.
Both ESA and AstroAccess argue that now is the time to consider accessibility in space, before the spacefaring vehicles of the future are finalized.
“Retrofitting is hard,” Wells-Jensen says. “Building things the way you want them is much easier.”
That could be especially important for private companies like SpaceX that are designing moon vehicles. The Federal Aviation Administration, which oversees commercial space transportation, has a legal moratorium on setting regulations about the safety of participants in private spaceflights until October 2023 to give the industry time to get established and collect data. AstroAccess, for one, wants to help guide those regulations.
“We want to fundamentally change the way humanity goes to space,” Wells-Jensen says. “We can’t become a spacefaring species if only some of us can go.”