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Artemis missions will usher in a new, more diverse crew of astronauts




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.”

Apollo 17 crew, Harrison Schmitt (back left), Eugene Cernan (front) and Ronald Evans (back right) pose for a photo in their practice space suits
The first groups of U.S. astronauts were white men. Apollo 17’s crew was Harrison Schmitt (back left), Eugene Cernan (front) and Ronald Evans (back right). NASA

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.

A photo of the 10 astronaut candidates for 2022 in their blue flightsuits
The most recent class of NASA astronaut candidates is more diverse.NASA

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, 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.

NASA engineers wear spacewalk backpacks with headlamps in a dark space
NASA engineers wear spacewalk backpacks with headlamps to practice sample collection in New Mexico. At the lunar south pole, some regions will be in permanent shadow.NASA

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.

A man and woman stand in a prototype of a new lunar landing spacesuit
In a prototype space suit — the actual Artemis suit is not yet designed —
NASA astronauts Zena Cardman and Drew Feustel train on a lunar-like landscape in Arizona.

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.

Crew photo for an AstroAccess flight with the plane in the background
To show that disabled people can be an asset on spaceflights, AstroAccess took the crew above on a zero gravity flight. Linguist Sheri Wells-Jensen (back row, second from left), who is blind, was surprised that her usual instincts worked differently in zero G.ASTROACCESS/ZERO G CORPORATION

“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.

A woman floating upside down in the foreground while others float behind her
Sheri Wells-Jensen (upside down) and other AstroAccess ambassadors float in zero g to test out what life would be like in space for people with disabilities.ASTROACCESS/ZERO G CORPORATION

“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.”

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The Kuiper Belt’s dwarf planet Quaoar hosts an impossible ring





The dwarf planet Quaoar has a ring that is too big for its metaphorical fingers. While all other rings in the solar system lie within or near a mathematically determined distance of their parent bodies, Quaoar’s ring is much farther out.

“For Quaoar, for the ring to be outside this limit is very, very strange,” says astronomer Bruno Morgado of the Federal University of Rio de Janeiro. The finding may force a rethink of the rules governing planetary rings, Morgado and colleagues say in a study published February 8 in Nature.

Quaoar is an icy body about half the size of Pluto that’s located in the Kuiper Belt at the solar system’s edge (SN: 8/23/22). At such a great distance from Earth, it’s hard to get a clear picture of the world.


So Morgado and colleagues watched Quaoar block the light from a distant star, a phenomenon called a stellar occultation. The timing of the star winking in and out of view can reveal details about Quaoar, like its size and whether it has an atmosphere.

The researchers took data from occultations from 2018 to 2020, observed from all over the world, including Namibia, Australia and Grenada, as well as space. There was no sign that Quaoar had an atmosphere. But surprisingly, there was a ring. The finding makes Quaoar just the third dwarf planet or asteroid in the solar system known to have a ring, after the asteroid Chariklo and the dwarf planet Haumea (SN: 3/26/14; SN: 10/11/17).

Even more surprisingly, “the ring is not where we expect,” Morgado says.

Known rings around other objects lie within or near what’s called the Roche limit, an invisible line where the gravitational force of the main body peters out. Inside the limit, that force can rip a moon to shreds, turning it into a ring. Outside, the gravity between smaller particles is stronger than that from the main body, and rings will coalesce into one or several moons.

“We always think of [the Roche limit] as straightforward,” Morgado says. “One side is a moon forming, the other side is a ring stable. And now this limit is not a limit.”


For Quaoar’s far-out ring, there are a few possible explanations, Morgado says. Maybe the observers caught the ring at just the right moment, right before it turns into a moon. But that lucky timing seems unlikely, he notes.

Maybe Quaoar’s known moon, Weywot, or some other unseen moon contributes gravity that holds the ring stable somehow. Or maybe the ring’s particles are colliding in such a way that they avoid sticking together and clumping into moons.

The particles would have to be particularly bouncy for that to work, “like a ring of those bouncy balls from toy stores,” says planetary scientist David Jewitt of UCLA, who was not involved in the new work.

The observation is solid, says Jewitt, who helped discover the first objects in the Kuiper Belt in the 1990s. But there’s no way to know yet which of the explanations is correct, if any, in part because there are no theoretical predictions for such far-out rings to compare with Quaoar’s situation.

That’s par for the course when it comes to the Kuiper Belt. “Everything in the Kuiper Belt, basically, has been discovered, not predicted,” Jewitt says. “It’s the opposite of the classical model of science where people predict things and then confirm or reject them. People discover stuff by surprise, and everyone scrambles to explain it.”


More observations of Quaoar, or more discoveries of seemingly misplaced rings elsewhere in the solar system, could help reveal what’s going on.

“I have no doubt that in the near future a lot of people will start working with Quaoar to try to get this answer,” Morgado says.

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Charon’s Freezing Ocean Produced Huge Canyons on Its Surface, Modeling Study Suggests | Sci.News





When ocean-bearing moons begin to cool down, their oceans can freeze. As new ice accretes to the bottom of the existing ice shell, the added volume of the ice can stress the shell. Pluto’s largest moon, Charon, has canyons and cryovolcanic flows that may have formed in response to a freezing ocean. In new research, planetary scientists from the Southwest Research Institute, the University of California, Davis, and the University of California, Berkeley modeled the formation of fractures within Charon’s ice shell as the ocean underneath it freezes to explore the evolution of the moon’s interior and surface. They found that an ocean source for cryovolcanic flows is unlikely because the ice shell would have had to be much thinner than current thermal evolution models imply; however, freezing the ocean may have produced the stresses that formed canyons later in Charon’s history.
Rhoden et al. revisited New Horizons data to explore the source of cryovolcanic flows and an obvious belt of fractures on Charon. Image credit: NASA / Johns Hopkins University Applied Physics Laboratory / Southwest Research Institute.

Rhoden et al. revisited New Horizons data to explore the source of cryovolcanic flows and an obvious belt of fractures on Charon. Image credit: NASA / Johns Hopkins University Applied Physics Laboratory / Southwest Research Institute.

“A combination of geological interpretations and thermal-orbital evolution models implies that Charon had a subsurface liquid ocean that eventually froze,” said Dr. Alyssa Rhoden, a researcher at the Southwest Research Institute.


“When an internal ocean freezes, it expands, creating large stresses in its icy shell and pressurizing the water below.”

“We suspected this was the source of Charon’s large canyons and cryovolcanic flows.”

New ice forming on the inner layer of the existing ice shell can also stress the surface structure.

To better understand the evolution of the moon’s interior and surface, Dr. Rhoden and colleagues modeled how fractures formed in Charon’s ice shell as the ocean beneath it froze.

They modeled oceans of water, ammonia or a mixture of the two based on questions about the makeup.


Ammonia can act as antifreeze and prolong the life of the ocean; however, results did not differ substantially.

When fractures penetrate the entire ice shell and tap the subsurface ocean, the liquid, pressurized by the increase in volume of the newly frozen ice, can be pushed through the fractures to erupt onto the surface.

Models sought to identify the conditions that could create fractures that fully penetrate Charon’s icy shell, linking its surface and subsurface water to allow ocean-sourced cryovolcanism.

However, based on current models of Charon’s interior evolution, ice shells were far too thick to be fully cracked by the stresses associated with ocean freezing.

The timing of the ocean freeze is also important. The synchronous and circular orbits of Pluto and Charon stabilized relatively early, so tidal heating only occurred during the first million years.


“Either Charon’s ice shell was less than 10 km (6 miles) thick when the flows occurred, as opposed to the more than 100 km (60 miles) indicated, or the surface was not in direct communication with the ocean as part of the eruptive process,” Dr. Rhoden said.

“If Charon’s ice shell had been thin enough to be fully cracked, it would imply substantially more ocean freezing than is indicated by the canyons identified on Charon’s encounter hemisphere.”

Fractures in the ice shell may be the initiation points of these canyons along the global tectonic belt of ridges that traverse the face of Charon, separating the northern and southern geological regions of the moon.

If additional large extensional features were identified on the hemisphere not imaged by NASA’s New Horizons spacecraft, or compositional analysis could prove that Charon’s cryovolcanism originated from the ocean, it would support the idea that its ocean was substantially thicker than expected.

“Ocean freezing also predicts a sequence of geologic activity, in which ocean-sourced cryovolcanism ceases before strain-created tectonism,” Dr. Rhoden said.


“A more detailed analysis of Charon’s geologic record could help determine whether such a scenario is viable.”

The study was published in the journal Icarus.


Alyssa Rose Rhoden et al. 2023. The challenges of driving Charon’s cryovolcanism from a freezing ocean. Icarus 392: 115391; doi: 10.1016/j.icarus.2022.115391

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Mimas Has an Expanding, Young Ocean, New Research Suggests | Sci.News





Mimas, a small moon of Saturn, is heavily cratered and lacks the typical characteristics of an ocean-bearing moon, such as the active surface of Enceladus. However, measurements of Mimas, made by NASA’s Cassini mission, are best explained by an ocean under a relatively thick ice shell. In new research, a duo of planetary scientists tried to understand how this ice shell and ocean may have changed with time by modeling the formation of Mimas’ largest impact basin, Herschel.
Mimas’ heavily cratered surface suggests a cold history, but its librations rule out a homogeneous interior. Rather, Mimas must have a rocky interior and outer hydrosphere, which could include a liquid ocean or be fully frozen with a non-hydrostatic core. Image credit: NASA / JPL-Caltech / Space Science Institute.

Mimas’ heavily cratered surface suggests a cold history, but its librations rule out a homogeneous interior. Rather, Mimas must have a rocky interior and outer hydrosphere, which could include a liquid ocean or be fully frozen with a non-hydrostatic core. Image credit: NASA / JPL-Caltech / Space Science Institute.

Mimas is the innermost, and smallest (radius = 198.2 km, or 123 miles), regular moon of Saturn.


The moon’s surface is heavily cratered, and it is easily identified by the large Herschel impact basin.

Tectonic activity on Mimas is sparse, and there is no evidence of past or present volcanism.

“In the waning days of NASA’s Cassini mission to Saturn, the spacecraft identified a curious libration, or oscillation, in Mimas’ rotation, which often points to a geologically active body able to support an internal ocean,” said Dr. Alyssa Rhoden, a researcher at Southwest Research Institute.

“Mimas seemed like an unlikely candidate, with its icy, heavily cratered surface marked by one giant impact crater that makes the small moon look much like the Death Star from Star Wars.”

“If Mimas has an ocean, it represents a new class of small, ‘stealth’ ocean worlds with surfaces that do not betray the ocean’s existence.”


Dr. Rhoden and Purdue University graduate student Adeene Denton wanted to better understand how a heavily cratered moon like Mimas could possess an internal ocean.

They modeled the formation of the Hershel impact basin using iSALE-2D simulation software.

The models showed that Mimas’ ice shell had to be at least 55 km (34 miles) thick at the time of the Herschel-forming impact.

In contrast, observations of Mimas and models of its internal heating limit the present-day ice shell thickness to less than 30 km (19 miles) thick, if it currently harbors an ocean.

These results imply that a present-day ocean within Mimas must have been warming and expanding since the basin formed.


It is also possible that Mimas was entirely frozen both at the time of the Herschel impact and at present.

However, the authors found that including an interior ocean in impact models helped produce the shape of the basin.

“We found that Herschel could not have formed in an ice shell at the present-day thickness without obliterating the ice shell at the impact site,” said Denton, who is now a postdoctoral researcher at the University of Arizona.

“If Mimas has an ocean today, the ice shell has been thinning since the formation of Herschel, which could also explain the lack of fractures on Mimas.”

“If Mimas is an emerging ocean world, that places important constraints on the formation, evolution and habitability of all of the mid-sized moons of Saturn.”


“Although our results support a present-day ocean within Mimas, it is challenging to reconcile the moon’s orbital and geologic characteristics with our current understanding of its thermal-orbital evolution,” Dr. Rhoden said.

“Evaluating Mimas’ status as an ocean moon would benchmark models of its formation and evolution.”

“This would help us better understand Saturn’s rings and mid-sized moons as well as the prevalence of potentially habitable ocean moons, particularly at Uranus.”

“Mimas is a compelling target for continued investigation.”

The results were published in the journal Geophysical Research Letters.



C.A. Denton & A.R. Rhoden. Tracking the Evolution of an Ocean Within Mimas Using the Herschel Impact Basin. Geophysical Research Letters, published online December 26, 2022; doi: 10.1029/2022GL100516

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