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Humans fit for space? — NASA’s Twins Study

[See comments for updates.]

Today (among others) published an article “Are Humans Fit for Space? A ‘Herculean’ Study Says Maybe Not” which summarizes NASA’s Twins Study which was published in Science (The NASA Twins Study: A multidimensional analysis of a year-long human spaceflight).


In space, fluids won’t drain, and astronauts develop red, puffy faces and complain of congestion or pressure in their ears. There are worse effects, too: 40 percent of the astronauts who lived on the International Space Station suffered some sort of damage to their eyes, … “spaceflight-associated neuro-ocular syndrome,” …

Over 25 months, the brothers submitted to a parallel routine of cognitive and physical tests—including a spinal tap for Scott—in the lab before, during, and after the mission. In all, 317 samples of stool, urine, and blood from both twins were collected and analyzed for their epigenomic, metabolomic, transcriptomic, proteomic, and microbiome changes. All of this was a first for NASA, which had never conducted a modern biological analysis of an astronaut, let alone of an astronaut and a monozygotic control.

The results, whose findings were finally published in Science today, expand our understanding of what happens to the human body after a year in space. “The NASA Twins Study: A Multidimensional Analysis of a Year-Long Human Spaceflight” is a triumph of cross-disciplinary science. Described as “a Herculean endeavor” by one of the article’s peer reviewers, it integrates the work of 10 different groups at universities around the country and 82 separate authors.

… the study provides only unsettling and incomplete answers. Long-term exposure to spaceflight is dangerous; based on what we know now, a journey to Mars is still too risky to contemplate.

The Wired article also includes a recap of Scott and Mark Kelly’s background, as well as noting that the NASA Study was far from glamorous (as part of an astronaut’s life, whether in space or on the ground) — an extended tedium of collecting samples and performing tests. The article references Scott Kelly’s book in which he describes the International Space Station as deafeningly noisy and smelly.

The authors of the NASA twins study helpfully distinguish between the potentially low-risk, mid-level or unknown risks, and high-risk effects of a year-long spaceflight … [and what biological, physiological, and cognitive changes returned to normal in 6 months or not].

All of which is far from that grand vision of “Man in Space” that Disney promoted when I was growing up. Its “practical look (through humorous animation) at what humans in space will have to face in a rocket (both physically and psychologically, such as momentum, weightlessness, radiation, even space sickness)” wasn’t a major takeaway then.

Man in Space” is an episode of the American television series Disneyland which originally aired on March 9, 1955. It was directed by Disney animator Ward Kimball. This Disneyland episode (set in Tomorrowland), was narrated partly by Kimball and also by such scientists Willy LeyHeinz Haber, and Wernher von Braun; as well as Dick Tufeld of Lost in Space fame.

“Man in Space” was edited into a featurette to play in theaters, accompanying “Davy Crockett and the River Pirates“. 

An adaptation of the episode was published (under the title “Walt Disney’s Man in Space: A Science Feature from Tomorrowland”) by Dell Comics as “Four Color” #716 in 1956, scripted by Don R. Christensen with art by Tony Sgroi.[ It was a “novelization” in comic book form of two Walt Disney television programs, “Man in Space” (1955) and “Tomorrow the Moon” (1955). 

The NASA article summarizes findings of the ten research teams:

  • Telomeres
  • Immunome
  • Gene Expression
  • Cognition
  • Biochemical
  • Microbiome
  • Epigenomics
  • Metabolomics
  • Proteomics
  • Integrative Omics

NASA’s Human Research Program (HRP) is dedicated to discovering the best methods and technologies to support safe, productive human space travel. HRP enables space exploration by reducing the risks to astronaut health and performance using ground research facilities, the International Space Station, and analog environments. 


MICEHAB [visualization]

Future NASA Missions Spark Out-of this-World Ideas: A Concept to Study How Space Affects Multiple Generations

A more recent investment fund project involved a study of how mice might help humans get to Mars. Eighteen NASA Langley researchers and eight students proposed the idea of a MICEHAB, a Multigenerational Independent Colony for Extraterrestrial Habitation, Autonomy, and Behavior health.

A scholarly paper and an animation produced by NASA Langley’s Advanced Concepts Lab help explain and illustrate their concept. But before anyone expresses concerns about the possible mice test subjects, the researchers want to stress this is just an idea. 

NASA Langley Research Center
Published on Jul 7, 2016
Researchers at NASA’s Langley Research Center in Hampton, Virginia, have an idea about how mice could help humans get to Mars. This video accompanies a scholarly paper.

Gamma rays

Due to their penetrating nature, gamma rays require large amounts of shielding mass to reduce them to levels which are not harmful to living cells, in contrast to alpha particles, which can be stopped by paper or skin, and beta particles, which can be shielded by thin aluminium. Gamma rays are best absorbed by materials with high atomic numbers and high density, which contribute to the total stopping power. Because of this, a lead (high Z) shield is 20–30% better as a gamma shield than an equal mass of another low-Z shielding material, such as aluminium, concrete, water, or soil; lead’s major advantage is not in lower weight, but rather its compactness due to its higher density. Protective clothing, goggles and respirators can protect from internal contact with or ingestion of alpha or beta emitting particles, but provide no protection from gamma radiation from external sources.


Beta rays

Alpha radiation consists of helium nuclei and is readily stopped by a sheet of paper. Beta radiation, consisting of electrons or positrons, is stopped by thin aluminum plate, but gamma radiation requires shielding by dense material such as lead, steel, or concrete.

Reference:’s article “First-Ever Image of a Terrestrial Gamma-Ray Burst Shows Light Exploding Out of a Thundercloud in Asia” by Brandon Specktor (May 21, 2019):

Astronomers observed the storm from a special observatory aboard the International Space Station, which launched in April 2018 with the purpose of monitoring the entire visible face of Earth for terrestrial gamma-ray activity. Hopefully, this is just the first of many such images. After one year of operations, the observatory has captured more than 200 terrestrial gamma-ray flashes, and was able to pinpoint the exact geographic location of about 30 of them, according to a statement from the European Space Agency (ESA).

32 thoughts on “Humans fit for space? — NASA’s Twins Study

  1. That bold vision of Disney’s “Man in Space” was part of NASA’s culture also, as Scott Kelly describes in his book:

    When I became an astronaut and started getting to know my astronaut classmates, many of us shared the same memory of coming downstairs in our pajamas as little kids to watch the moon landing. Most of them had decided, then and there, to go to space one day. At the time, we were promised that Americans would land on the surface of Mars by 1975, when I was eleven.

    Everything was possible now that we had put a man on the moon. Then NASA lost most of its funding, and our dreams of space were downgraded over the decades. Yet my astronaut class was told we would be the first to go to Mars, and we believed it so fully that we put it on the class patch we wore on our flight jackets, a little red planet rising above the moon and the Earth. Since then, NASA has accomplished the assembly of the International Space Station, the hardest thing human beings have ever achieved. Getting to Mars and back will be even harder, and I have spent a year in space—longer than it would take to get to Mars—to help answer some of the questions about how we can survive that journey. — Kelly, Scott. Endurance (pp. 11-12). Knopf Doubleday Publishing Group. Kindle Edition.

  2. Scott Kelly begins his book with recollections of his health after spending a year in space:

    As I try to will myself to sleep, I wonder whether my friend Mikhail Kornienko is also suffering from swollen legs and painful rashes—Misha is home in Moscow after spending nearly a year in space with me. I suspect so. This is why we volunteered for this mission, after all: to discover how the human body is affected by long-term spaceflight. Scientists will study the data on Misha and me for the rest of our lives and beyond. Our space agencies won’t be able to push out farther into space, to a destination like Mars, until we can learn more about how to strengthen the weakest links in the chain that makes spaceflight possible: the human body and mind. People often ask me why I volunteered for this mission, knowing the risks — the risk of launch, the risk inherent in spacewalks, the risk of returning to Earth, the risk I would be exposed to every moment I lived in a metal container orbiting the Earth at 17,500 miles per hour. I have a few answers I give to this question, but none of them feels fully satisfying to me. None of them quite answers it. — Kelly, Scott. Endurance (pp. 7-8). Knopf Doubleday Publishing Group. Kindle Edition.

  3. The debate over aggressive schedules (accelerated timelines) to put humans on the Moon and Mars is alive and well, as evident in this article “Will NASA’s Rush to Land Astronauts on the Moon Get Us to Mars Any Faster?” (May 17, 2019).

    A mission to the moon may be a good “steppingstone” for sending humans to Mars, but the experts are divided over whether NASA’s new push to put humans on the moon in 2024 will help get the agency to Mars by the 2030s.

    “We’re going to the moon because we want to get to Mars with humans,” NASA Administrator Jim Bridenstine said Tuesday (May 14) here at the Humans to Mars Summit. By accelerating the timeline for getting astronauts back on the moon, “we are by definition accelerating the humans to Mars program,” he added.

    The agency has said that it plans to land astronauts on Mars in the 2030s, following President Barack Obama’s request in 2016. The following year, Trump requested a nongovernmental, independent report about the possibility of launching humans to Mars in 2033 in his NASA Authorization Act of 2017. Although Bridenstine has said that NASA wants to achieve a landing in 2033, he hasn’t offered a new timeline for Mars based on the moon mission just yet.

    Is money the challenge? Technology, including robotics? Orbital infrastructure around the Moon (platform gateway) and Mars? A JFK-like “big call” to action? Another space race?

    I think Scott Kelly’s cautions are important.

    A fellow Caltech alumnus was a systems engineer at a large (well known) corporation. Both he and I worked on programs which pushed the limits of new technology (including software). Throwing more resources (people, money, etc.) on a program when things were behind schedule or went wrong was iffy. System requirements … a state of flux. As he said recently about a new business meeting with a customer years ago, “We will charge you while we make the mistake, and again when we fix it.”

  4. This arsTechnica article “NASA’s full Artemis plan revealed: 37 launches and a lunar outpost” (May 20, 2019) provides more detail on the “return to the Moon” plan.

    Last week, an updated plan that demonstrated a human landing in 2024, annual sorties to the lunar surface thereafter, and the beginning of a Moon base by 2028, began circulating within the agency. A graphic, shown below, provides information about each of the major launches needed to construct a small Lunar Gateway, stage elements of a lunar lander there, fly crews to the Moon and back, and conduct refueling missions.

    Although the plan is laudable in that it represents a robust human exploration of deep space, scientific research, and an effort to tap water resources at the Moon, it faces at least three big problems [3 miracles].

  5. And this article “Space Tourism Is about to Push Civilian Astronaut Medicine into the Final Frontier — Are you healthy enough for spaceflight, or just wealthy enough?” by Meghan Bartels (May 21, 2019) is a good overview of the coming challenges for space medicine when “the wealthy stuff” qualifies for trips in space.

    The article includes a photo of Stephen Hawking on the tarmac before a 2007 flight in ZERO-G.

    Many more tourists have already experienced zero-gravity conditions for brief snippets of time during parabolic flights. ZERO-G has flown more than 15,000 passengers — including Stephen Hawking …

    Right now, there aren’t any rules requiring space tourism companies to set or meet any health criteria for accepting passengers — they just need to have each customer sign a statement saying they understand the risks of such a flight. (Although Scheuring [a flight surgeon at NASA’s Johnson Space Center in Texas] notes that there’s no guarantee scientists have identified all of those risks to date, especially for passengers without NASA’s prerequisite “perfect” body.)

    As to where the “edge of space” is (Wiki):

    The Kármán line, or Karman line, is an attempt to define a boundary between Earth’s atmosphere and outer space. This is important for legal and regulatory measures; aircraft and spacecraft fall under different jurisdictions and are subject to different treaties.

    The Fédération aéronautique internationale (FAI; English: World Air Sports Federation), an international standard-setting and record-keeping body for aeronautics and astronautics, defines the Kármán line as the altitude of 100 kilometres (62 miles; 330,000 feet) above Earth’s sea level. Other organizations do not use this definition. For instance, the US Air Force and NASA define the limit to be 50 miles (80 kilometres) above sea level for purposes of awarding personnel with outer space badges.

  6. So, a family member asked: “I wonder who will be first to implement rotating spacecraft for partial gravity simulation for long duration stays away from gravity wells.”

    I found this 2014 NASA report “Artificial Gravity Future Plans for ISS” (link below). It’s a 21-slide PDF presentation. It has an excellent table which summarizes the Human Risks of Spaceflight, including one of Scott Kelly’s favorites: CO2 exposure.

    This report does not get into the engineering and operation of Artificial Gravity (AG); but, after reading Scott Kelly’s book about his stays on the ISS and problems with power management and vibrations (even from the treadmill) which can cause damaging oscillations, I think there are technical challenges. Yet another example of how Disney’s “Man in Space” was so credulous.

    Other references:

    1. [See the Proposals and Issues with implementation sections.]


    2. [“The Rise and Fall of Artificial Gravity – Giant, spinning space-stations that generate their own artificial gravity have been envisaged for decades. So, why has no one built one?” 18 November 2014]

    3. [“Geek Answers: Why doesn’t the ISS have artificial gravity?” 7-27-2013]

    4. [“Artificial gravity’s attraction” April 2017]

  7. Well, it’s official now: NASA announced this week that “the wealthy stuff” qualifies for trips to the ISS, starting next year.

    NASA invites tourists to space station” (June 7, 2019)

    NASA … announced a plan to allow private citizens to fly to the International Space Station and stay for the tidy sum of $35,000 per night. This news flash, representing a major change in policy for NASA …

    The agency wants to open the International Space Station to more commercial interests, including filming advertisements. While NASA touted the plan as a way to help fund its ambitious plan to return astronauts to the moon by 2024 as it tries to build a sustainable economy in space, it’s unclear how much the agency stands to make under the new policy.

    NASA’s announcement is a significant change for the agency, which has had a long-standing prohibition against allowing tourists on the station. Russia, however, has allowed several private astronauts on the station.

    Under the NASA plan, as many as two private citizens per year could fly to the station and stay for up to 30 days, with the first mission coming as early as next year.

    Jeff DeWit, NASA’s chief financial officer, estimated the cost per trip would be about $50 million a seat. But the cost and arrangements would be left to SpaceX and Boeing, the two companies NASA has hired to fly crews to the station. They would keep that money and also have to make sure that private astronauts “meet NASA’s medical standards and the training and certification procedures” for crew members.

    Personally, for anyone or any company envisioning going to the ISS, I’d recommend careful reading of Scott Kelly’s book Endurance. What an eye-opener!

    Scott Kelly's year in space on the ISS.

    See also: “Civilians will soon be greenlit to rocket to the International Space Station — Got $50 million lying around? Then an outer space vacation may be in your future” (June 7, 2019).

    But soon, you’ll have a simpler way to leave Earth’s atmosphere, as long as you’re filthy rich. According to a report Friday by the Washington Post, NASA will soon let civilians travel to the International Space Station for a projected cost of $50 million. That’s not an all-expenses-included fee, either.

    The International Space Station could soon become humanity's next hottest tourist destination.

  8. This article “Artificial gravity breaks free from science fiction” discusses research by a team from CU Boulder and how gradual conditioning can prevent “cross-coupled illusion” – “a disruption of the inner ear that makes you feel like you’re tumbling.”

    The researchers, led by aerospace engineer Torin Clark, can’t mimic those Hollywood creations—yet. But they are imagining new ways to design revolving systems that might fit within a room of future space stations and even moon bases. Astronauts could crawl into these rooms for just a few hours a day to get their daily doses of gravity. Think spa treatments, but for the effects of weightlessness.

    The group reported its results in June in the Journal of Vestibular Research.

  9. Re the “return to the Moon” plan, this article discusses why we’ve not gone back in 50 years: “It’s 2019. Why Haven’t Humans Gone Back to the Moon Since the Apollo Missions? — The conditions that incubated Apollo just aren’t around anymore” (July 21, 2019).

    “The Apollo days were not, fundamentally, about going to the moon,” John Logsdon, a professor emeritus of political science and international affairs at The George Washington University’s Elliott School of International Affairs in Washington, D.C., told “They were about demonstrating American global leadership in a zero-sum Cold War competition with the Soviet Union.

    So NASA got the resources it needed to pull off its moon shot. And those resources were immense — about $25.8 billion for Apollo from 1960 through 1973, or nearly $264 billion in today’s dollars. During the mid-1960s, NASA got about 4.5% of the federal budget — 10 times greater than its current share.

    The stakes haven’t been nearly as high since the end of the Cold War, so subsequent moon projects haven’t enjoyed such sustained support. (They likely also suffered from some been-there-done-that sentiment.) For example, the Constellation Program, which took shape under President George W. Bush, was canceled in 2010 by President Barack Obama.

    Obama directed NASA to instead send astronauts to a near-Earth asteroid. But President Donald Trump nixed that plan in 2017, putting the agency back on course for the moon.

  10. This article “Scott Kelly: The American Astronaut Who Spent a Year in Space” by Elizabeth Howell (Sept 4, 2019) is a brief biography of the astronaut.

    Kelly has remained active in spaceflight activities even after retiring from NASA. In fall 2017, he published his autobiography “Endurance: A Year in Space, A Lifetime of Discovery” (Viking, 2017). The title of his book was inspired by Alfred Lansing’s “Endurance” (Hodder and Stoughton, 1959), about Ernest Shackleton’s Antarctic expedition. Kelly brought a copy of Lansing’s book with him to space during his last mission, and left it behind in the space station’s small library when he came back to Earth, he recalled in the biography.

    In 2016, Sony Pictures announced it had secured the film rights for “Endurance.”

    PBS and Time did a follow-up documentary on Kelly called “Beyond A Year in Space,” which examined Kelly’s return to Earth and subsequent medical testing …

  11. Visions of space hotels? Cost, safety, sustainability, … This NBC News article summarizes some imaginative plans for orbiting hotels in the coming decades: “Huge space hotel promises fake gravity and ‘supersized basketball’ – The planned Von Braun Station could open as soon as 2027″ (Sept 14, 2019).

    Though space hotels have long belonged only to the world of make-believe, that’s about to change. NASA says it will open the International Space Station (ISS) to tourists as early as 2020. A Houston-based startup called Orion Span has proposed a four-guest space hotel called Aurora Station that would open in 2022.

    And now the Gateway Foundation, a startup in Alta Loma, California, is planning what may be the most ambitious space hotel project of all: a sort of space-based cruise ship big enough to hold a pair of hotels that would accommodate 100 guests and perhaps three times as many crew members. The facility would feature artificial gravity and have restaurants, gyms, sports arenas and concert venues as well as spaceplanes ready to whisk guests back to Earth in case of an emergency.

  12. Universe Today > Space and astronomy news: “Real Artificial Gravity for SpaceX’s Starship” (Sept 16, 2019)

    Interesting visualizations.

    Real Artificial Gravity for SpaceX’s Starship

    Despite the many, many problems we face in the world today, it is still an exciting time to be alive! As we speak, mission planners and engineers are developing the concepts that will soon take astronauts on voyages beyond Low Earth Orbit (LEO) for the first time in almost fifty years. In addition to returning to the Moon, we are also looking further afield to Mars and other distant places in the Solar System.

    This presents a number of challenges, not the least of which are the effects of prolonged exposure to radiation and microgravity. And whereas there are many viable options for protecting crews from radiation, gravity remains a bit of a stumbling block. To address this, Youtuber smallstars has proposed a concept that he calls the Gravity Link Starship (GLS), a variation of SpaceX’s Starship that will be able to provide its own artificial gravity.

    1. YouTube video

    YouTube Video Description: Real Artificial Gravity for SpaceX’s Starship
    Channel: smallstars
    Published on Aug 27, 2019

    Why go to mars like it’s 1995 if artificial gravity can be practical by 2024?

    This is a concept that I am describing with an animation. The design as seen in the animation is just a visual representation and will likely be improved in future versions. The goal of the Gravity Link Starship concept is to provide a spin gravity that re-uses the main engines, taps left over fuel, and avoids impractical space construction and spacewalks.

    The GLS is basically a hub ship, like the hub of a wheel. Instead of humans and cargo the payload bay of the GLS is filled with truss that can robotically fold out and lock into place serving as the wheel’s spokes.

    Once on the way to a distant destination like Mars, 2 Passenger Starships will make their approach to the attachment points at the ends of the deployed truss. Once attached, one Starship remains fixed while the other one slowly rotates it’s orientation on it’s swivel joint.

    At this point the main engines will facing opposite each other and will be used to spin the system, thus creating a centripetal force equal to earths gravity.

    When the desired spin speed and by extension amount of artificial gravity force is achieved, both Starships will swivel themselves into a resting position which is an orientation in line with the truss so that gravity is pulling in the correct direction, down towards the bottom of the ships.

    2. YouTube video

    SpaceX Interplanetary Transport System
    Published on Sep 27, 2016
    Channel: SpaceX
    Category: Science & Technology

  13. Speaking of SpaceX, how will their Starship keep people alive and safe during extended space travel? This article is an excellent overview of Elon Musk’s Starship and what’s needed to survive a trip to Mars: TheVerge > “Elon Musk’s future Starship updates could use more details on human health and survival – People are supposed to fly on this thing, after all” by Loren Grush (Oct 4, 2019)

    SpaceX CEO Elon Musk has now given four presentations about his company’s Starship rocket, but all of those updates mostly focused on the vehicle’s external stats. Musk has barely touched on the technologies needed to keep people alive and healthy while on Starship — technologies that need to be developed relatively soon if the spacecraft has any hope of carrying people to deep-space destinations like the Moon and Mars in the near future.

    Musk says only 5 percent of SpaceX’s resources are being used to develop Starship at the moment, which may explain why the rocket is the sole focus. At some point, the humans will need to be addressed, though. It’s just a matter of when.

  14. So, studies continue on the effects of living in space, as noted in this article. Key research includes developing ways to reduce negative effects. > Home News Spaceflight > “Space travel can seriously change your brain” by Chelsea Gohd (April 14, 2020) – This is your brain on space.

    Scientists suspect that these vision issues are caused by increased “intracranial pressure,” or pressure in the head, during spaceflight. In a new study led by Dr. Larry Kramer, a radiologist at the University of Texas Health Science Center at Houston, researchers have found evidence that this pressure does, in fact, increase in microgravity.

    The researchers also found that these effects, the swelling of the brain alongside the compressing pituitary gland and the pressure in the head, was still present a year after the astronauts returned from space. That duration suggests that these effects could be long-lasting, Kramer said. However, further study is needed to evaluate exactly how microgravity affects the brain over an astronaut’s lifetime and how this might vary between people, Kramer said.

  15. Research continues on the impact of extended missions in space on our bodies. > “Space travel may impact how the body handles sodium” by American Heart Association (May 12, 2020).

    A new study reports that astronauts excrete less sodium in space than on land, a finding that could have implications for the heart health of future space travelers.

    Past research shows exploring the cosmos poses a range of health risks for humans, affecting their brain, eyes and bones. Space travel has a particularly noticeable impact on the cardiovascular system.

    The new research, published Monday in the American Heart Association journal Circulation, focused on cardiac natriuretic peptides, a hormone which helps the body urinate out sodium. Researchers said the study was the first to measure these peptides in astronauts eating a high-sodium versus low-sodium diet in space and on Earth.

    The study included eight male astronauts who each ate both low- and high-sodium diets in space and on Earth. The low-sodium diet was 2 grams a day and the high-sodium diet was 5.5 grams. In addition, 16 cosmonauts were assessed for changes in blood volume before, during and after being in space.

  16. ISS photo

    Crew Dragon

    NASA astronaut Chris Cassidy snapped this photo of SpaceX’s Crew Dragon vehicle docked with the International Space Station during a spacewalk with Bob Behnken on Friday, June 26, 2020. (Image credit: Bob Behnken/Twitter)

  17. Another follow-up to NASA’s Twins Study regarding the effects of long-duration space exploration (even journeys to Mars). When our hearts no longer pump blood “uphill” for extended periods of time, our hearts lose mass.

    • BBC > “Long spaceflights and endurance swimming can ‘shrink the heart’” by Paul Rincon, Science editor, BBC News website (March 29, 2021) – Spending very long periods of time in space has something in common with extreme endurance swimming: both can cause the heart to shrink.

    The study was led by Dr Benjamin Levine, professor of internal medicine at the University of Texas Southwestern Medical Center in Dallas, and is published in the journal Circulation.

    “We saw specifically 19% and 27% of mass lost for Captain Kelly over the year.”

    [On the ISS, the intense] exercise regime wasn’t enough to prevent the heart atrophy seen in Captain Kelly.

    The heart adaptations, however, aren’t long-term – both men’s hearts returned to normal once they were back on terra firma.

    Risks remain, however, while in space.

    Prof Levine is part of a Nasa programme called Cipher that will send another 10 astronauts into space for long-duration missions. The researchers will subject the crew members’ hearts to a number of different tests and high-tech scanning methods for a more detailed picture of heart function in space.

  18. In the news: Space travel and the risk of genetic damage from ionizing radiation.

    • Engadget > “Astronauts show how CRISPR gene editing works in space” by J. Fingas (July 4, 2021) – The technique could be key to long-term space travel.

    The new approach [using yeast cell culture aboard the International Space Station] clears the way for other research around DNA repair in space. With enough work, the scientists hope they can replicate the genetic damage from ionizing radiation, not to mention other effects from long-term spaceflight. That, in turn, could help NASA and other agencies develop technology that shields astronauts and makes deep space exploration practical. There’s a chance CRISPR might play an important role in getting humans to Mars and beyond.

    • > “NASA wants to change the way it protects astronauts from radiation” by Rahul Rao (July 2, 2021) – The proposed guideline would give all astronauts the same radiation limit, set to the standard for the most vulnerable population, which is the 35-year-old woman.

    The proposed changes come as NASA prepares to send astronauts beyond Earth’s orbit [to the Moon, Mars, …].

    Currently, NASA calculates that cap based on a risk estimate. The limit is the amount of total exposure that would give an astronaut a 3% higher chance of dying of cancer in the rest of their life, based on available data.

    In hard units, that’s a total of 600 millisieverts over a career with the agency. For comparison, a single chest X-ray at your doctor’s office gives you around 0.1 millisieverts, and you pick up around 3 millisieverts every year from Earth’s natural background radiation. Workers near Chernobyl’s ground zero in 1986 were showered with 6,000 millisieverts.

    Meanwhile, a six-month stay on the International Space Station exposes an astronaut to between 50 and 120 millisieverts, according to the new report. More distant destinations like Mars carry greater exposures.

  19. An interesting recap of ongoing research on the ISS regarding deterioration of muscles, bones, eyes and ears in space. Even a dreams experiment.

    • ESA > “New Year’s science in space for a healthier life” (Jan 6, 2022)

    Around 70% of astronauts experience changes in the optic nerve during a long stay in space, a phenomenon known as Space-Associated Neuro-ocular Syndrome (SANS). This vision pathology is also regarded as the number two risk to human health during a mission to Mars.

  20. Space anemia. Yikes! Making quite a media splash.

    • > “Being in space destroys more red blood cells” by The Ottawa Hospital (January 14, 2022)

    A world-first study has revealed how space travel can cause lower red blood cell counts, known as space anemia. … according to a study published in Nature Medicine.

    “Space anemia has consistently been reported when astronauts returned to Earth since the first space missions, but we didn’t know why,” said lead author Dr. Guy Trudel, a rehabilitation physician and researcher at The Ottawa Hospital and professor at the University of Ottawa.

    … Dr. Trudel’s team found that the red blood cell destruction was a primary effect of being in space, not just caused by fluid shifts.

    The [MARROW “Keeping blood healthy in space” experiment] researchers found that [ISS] astronauts were destroying 54 percent more red blood cells during the six months they were in space, or 3 million every second [vs. on Earth 2 million per second].

    “… The effects of anemia are only felt once you land, and must deal with gravity again” [with red blood cells levels progressively returning to normal three to four months after returning to Earth].

    And one year later, “… red blood cell destruction was still 30 percent above preflight levels.”


    • Screening for preexisting conditions.
    • Managing the impact during extended missions, as the effect worsens with duration.
    • Adapting diets.
    • Determining any time limits (as for radiation exposure) for maintaining a higher rate of destruction / production of red blood cells.

    Is the situation better if there’s artificial gravity?

  21. Wayback machine archive 1971 – Clarke, Bradbury, Sullivan, Sagan, Murray

    This week’s issue of Caltech Weekly noted a revealing panel discussion in 1971 about why we explore space. A discussion which continued over the decades regarding manned exploration. As promoted by The Planetary Society, for example. And SpaceX’s current planning for manned missions to Mars.

    What a stellar cast for a panel discussion. Even a follow-up book [1]. A discussion which set the stage for what’s currently playing out on Mars. Got rocks yet?

    • Caltech > Archives > “MARS AND THE MIND OF MAN

    (image caption) Left to right: Arthur C. Clarke, Ray Bradbury, Walter Sullivan, Carl Sagan, Bruce Murray. November 12, 1971, Ramo Auditorium, Caltech

    In anticipation of Mariner 9’s planned orbit around Mars, Caltech professor of planetary sciences Bruce Murray invited the following gentlemen to participate in a public symposium on “Mars and the Mind of Man”: the science fiction writers Ray Bradbury and Arthur C. Clarke, Cornell’s Director of the Laboratory for Planetary Studies Carl Sagan, who was a Caltech visiting associate and a member of the Mariner 9 television team along with Murray, and New York Times science editor Walter Sullivan. The symposium was held on November 12, 1971, on the eve of the probe’s planned orbital entry. Caltech later published a brief account in the January 1972 issue of Engineering and Science.

    Clarke evidently predicted that we’d be on Mars by 2000. A timeline similar to other wild visions, like Disney’s “Man in Space” series [2].

    I like this Bradbury quote (below) regarding the “misinformed theories and past misinterpreted observations” about Mars (in a wider context of speculation from limited data – in the modern era vs. ancient myth-making about the sky).

    “I think it’s part of the nature of man to start with romance and build to a reality. In order to get the facts we have to be excited to go out and get them and there’s only one way to do that—through romance.”

    And I hope that, as Sullivan is quoted as saying, science and reason will triumph over superstition. But many sci-fi sagas continue to portray superstition as a compelling force in far-future culture.


    [1] Amazon book link:

    Mars and the Mind of Man Hardcover – January 1, 1973
    by Ray Bradbury (Author), Arthur C. Clarke (Author), Bruce Murray (Author), Carl Sagan (Author), Walter Sullivan (Author)

    [2] Disneyland TV (1955 – 1957) Wiki links:

  22. Based on an article published in the journal Frontiers in Neural Circuits, here’s another plug for artificial gravity as a countermeasure to the effects of long-duration space travel on the human body.

    • > “Cosmonaut brains are ‘rewired’ by space missions, scientists find” by Chelsea Gohd (Feb 18, 2022)

    In a new study, a collaborative effort between the European Space Agency and Russia’s space agency Roscosmos, researchers have explored how cosmonauts’ brains change after traveling to space and back. And they showed how the brain adapts to spaceflight, finding that the brain is almost “rewired,” and both fluid shifts and shape changes occur. These changes can last for months after a person returns to Earth, the researchers found.



    Fiber tractography

    diffusion MRI

  23. A new record for US spaceflight for long-duration missions.

    • > “NASA astronaut Mark Vande Hei breaks record for longest US spaceflight” by Robert Z. Pearlman (March 15, 2022)

    At a mission elapsed time of 340 days, 8 hours and 42 minutes, Vande Hei will surpass the duration logged by NASA astronaut Scott Kelly on March 2, 2013.

    From Tuesday [March 15] afternoon forward, until his scheduled ride home on March 30, Vande Hei’s record will continue to grow. His stay aboard the International Space Station is expected to wrap just short of a full year at 355 days.

    (photo caption) NASA astronaut Mark Vande Hei, who is setting a new record for the longest U.S. spaceflight, said he has dealt with the extended mission by meditating while looking out into space from inside the International Space Station’s Cupola. (Image credit: NASA)

    Article references NASA’s info graphic on long-duration missions.

    Reduced size image

  24. Here’s another article about the role of artificial gravity for future off-world venues.

    • > “Artificial gravity: Definition, future tech and research” by Robert Lea published about 6 hours ago – Artificial gravity could revolutionize space exploration and off-Earth tourism.

    One possible way of creating artificial gravity in space is by utilizing a technology called an O’Neill cylinder. Named after the physicist who proposed them, Gerard O’Neill, this consists of a pair of massive cylinders that rotate in opposite directions, allowing them to be permanently directed toward the sun, replicating gravity.

    Researchers at the University of Boulder Colorado have a smaller scale suggestion — rotating systems that could fit inside the rooms of spacecraft.

    Another potential design for creating artificial gravity is a long spinning stick-like vehicle around 328 feet (100 metres) across with a nuclear reactor on one end and a crew compartment on the other for journeys to Mars. However, these have had engineering issues preventing their application.

    The Voyager space station is a planned rotating wheel space station set to begin construction in 2025. Pioneered by the Orbital Assembly Corporation (OAC) Voyager will differ from the International Space Station in two key ways; it will be open to the public, and it will have artificial gravity.

    Space colony
    Caption: Two space stations (NASA/Rick Guidice 1970’s)

  25. Among other methods, extended space missions in microgravity require targeted, regular (typically daily) exercise. One of the challenges of high-impact (jumping) exercise is damping forces from such activity on the spacecraft. In sci-fi space operas where there’s artificial gravity, there’s no worry, eh.

    • > “Astronauts may need to jump in space to fight bone loss” by Brett Tingley (July 1, 2022) – A new study suggests that high-impact exercise could help limit bone loss while in space.

    Out of the 17 astronauts who participated in the new study, which was published online Thursday (June 30) in the journal Scientific Reports, only eight regained full bone mass density one year after returning from flight. Bone density loss was found to be much higher in astronauts who flew on missions longer than six months.

    But the researchers also found that astronauts who engaged in resistance-based training while in space were able to recover bone mineral density after they returned. The authors thus propose adding “jumping resistance-based exercise [using specialized equipment] that provides high-impact dynamic loads on the legs” to astronauts’ existing exercise routines to prevent bone loss and promote bone growth while on spaceflight missions.

    Astronaut in space above Earth
    Credit: Pixabay/CC0 Public Domain

  26. This article provides an overview of alpha particles. What’s the risk?

    • > “Alpha particles and alpha radiation: Explained” by Stefanie Waldek (May 13, 2022) – Alpha particles (aka alpha rays or radiation) … pose little danger to humans unless ingested.

    Alpha [α] particles are positively charged particles that comprise two protons, two neutrons, and zero electrons [ as the nucleus of a helium-4 atom]. … Alpha particles are emitted from heavy radioactive elements (both naturally occurring and man-made), including uranium, radium, and plutonium. Because of this, these elements are also called alpha emitters.

    Commercially, alpha radiation is primarily used in smoke detectors.

    Alpha radiation is not dangerous to humans externally due to its low penetrating power; alpha particles cannot penetrate your skin. They can, however, cause damage to your cornea.

    The real danger occurs inside the body. If an alpha emitter (that is, a radioactive element) enters your body via ingestion, inhalation, a wound, or any other means, great damage could be done internally to living tissue.

    Diagram – alpha particle emission
    Wiki > Diagram of an alpha particle (α) being ejected from the nucleus of an atom. Protons are red and neutrons are blue.

  27. A recent issue of the journal Acta Astronautica called for an international database on long-term health effects of spaceflight – a major challenge. Even eventually any impacts of exposure to the Moon’s dust. Will there be an app for that?

    • > “Can we live long and prosper in space? The astronaut health dilemma” by Leonard David (9-20-2022) – Space medical scientists are pushing for the development of an international database on long-term health effects of spaceflight.

    … at NASA’s Johnson Space Center, gathering astronaut medical data was reconfigured in 2010 as an operational program within the space agency and renamed the Lifetime Surveillance of Astronaut Health. Call it LSAH for short.

    LSAH within NASA collects data fairly consistently on retired American and Canadian space crew members, Bloomfield [Susan Bloomfield, a research professor in health and kinesiology at Texas A&M University in College Station, Texas] said.

    … the Translational Research Institute for Space Health (TRISH), funded by a NASA Cooperative Agreement and based at the Baylor College of Medicine in Houston, has already established a medical/health database for commercial fliers’ in-flight data.

    NASA astronaut Scott Kelly spacewalk on Dec. 21, 2015
    Credit: NASA

  28. Spinning like a top

    Aside from the sheer engineering challenges of designing and operating a spinning spacecraft, there’re practical human factors.

    • Wired > “The Problem With Spinning Spacecraft” by Rhett Allain (Nov 11, 2022) – To send astronauts on long-term space missions, it’ll take rotating habitats to produce artificial gravity. But that’s trickier than you might think.

    (quote) If you want your spacecraft to have artificial gravity that mimics Earth’s and a reduced Coriolis effect, you are just going to need a bigger spaceship. It’s a tough choice: You can build a small, cheap spacecraft and deal with annoying Coriolis forces, or you can build a large, expensive spaceship with all the comforts of home – but that’ll be big, and it’s going to cost you.


    Linear acceleration
    Angular velocity
    Differential gravity
    Coriolis force

  29. Powdery dust

    In dust, there be dragons …

    Yeah, I’ve wondered about visions of manned colonies on the Moon and Mars – because of dust. Most sci-fi film and TV dramas bypass this challenge. A problem for human health & activity and equipment.

    Like donning and removing spacesuits on habitat egress and ingress. Portrayal of easy coming & going reminds me of something a veteran scuba instructor mentioned recently. A heater failure in an outdoor swimming pool resulted in the water temperature falling. To the point that he was considering bringing a half-wetsuit; but donning a wetsuit was a real hassle. Action movies in which secret agents swim to shore and quickly strip their drysuits off (maybe to reveal a tuxedo for infiltrating an elaborate party) – just are not real.

    • LA Times > “NASA prepares for the moon — and familiar foe” by Samantha Masunaga, reporting from Cape Canaveral FL – Stardust may be romantic, but lunar dust is a potential hazard.

    (article’s image caption) Scientists at the Swamp Works lab at Kennedy Space Center in Cape Canaveral, Fla., shown in 2019, are working on how to mitigate dust blown by rocket engines during lunar landings. (Jacob M. Langston / For The Times)

    (quote) Back during the Apollo program in the 1960s and early 1970s, the astronauts complained that they couldn’t put their gloves back on after three days because lunar dust had degraded the seals.

    … simulated dust particles — like the real thing [moon dust] — are so fine that they can get stuck in your lungs. To protect themselves, researchers who go into the large bin follow Occupational Safety and Health Administration rules and don protective suits, complete with head coverings, gloves and respirators. Even the lab’s housekeeper sweeping outside wears a respirator.

    Still, Mueller [Swamp Works co-founder Robert P. Mueller] has found dust between his toes after a day in the big bin. “Even in the suits,” he said, “it gets everywhere.”

    Mueller made the comments while leading a tour of the lab in 2019. Three years later, the challenges posed by moon dust persist — and still can’t be fully replicated in the big bin.

    The bigger the rocket, the more dangerous the plume, meaning lunar dust, gravel and rocks that get kicked up during landing or takeoff will travel at significantly higher speeds than during the Apollo missions.

    “It’s not just one exposure,” Metzger said. “We might end up having 20 to 30 exposures of sandblasting.”

    Even further out, though, the team’s research has implications beyond the lunar program. There’s dust on Mars too.

  30. Here’s a useful anatomically visualized recap of the effects from extended stays in space (at least low-earth orbit). And, in some cases, mitigating those effects.

    • Washington Post > “What space does to your body: Swollen heads, shrunken legs, round hearts” by Gretchen Reynolds and William Neff [1] (Jan 12, 2023) – Sequined darkness sparks our ambitions, dreams and stories, at a cost.

    (quote) “Space is just not very hospitable to the human body,” said Emmanuel Urquieta, chief medical officer at the Translational Research Institute for Space Health in Houston, which partners with NASA to study the effects of deep space exploration.

    Space motion sickness
    “Puffy Face Bird Leg Phenomenon”
    Face swelling
    Muscle atrophy
    Reduced blood volume
    Heart muscle atrophy
    Cell damage from radiation, including brain cells
    Systemic inflammation
    Bone thinning
    Eyeball flattening
    Higher volume of skull fluids
    Changes in gene activity
    Changes in circadian rhythms
    Psychological stress (solitude, confinement, etc.)


    [1] Additional design and development by Betty Chavarria. Editing by Kate Rabinowitz, Manuel Canales and Jeff Dooley. Copy editing by Wayne Lockwood.

    Recap of the effects from extended stays in space

  31. Gut-brain balance

    The immune system, hippocampus, neurotransmitter system, stress management, … the microbiota gut-brain axis. This article even mentions the film The Martian.

    • > “Space travel taxes astronauts’ brains. But microbes on the menu could help in unexpected ways” by Felice Jacka, Dorit Donoviel [1] (Jan 30, 2024) [originally published at The Conversation] [includes YouTube video on our microbiome] – Diet is important for astronauts’ mental and cognitive health.

    Diet quality is consistently and independently linked to the risk of depression or anxiety. Clinical trials show improving diet quality can lead to profound improvements in depression and anxiety symptoms.

    Diet also affects the size and function of a specific brain region – the hippocampus – that is crucial to learning and memory, as well as for maintaining mental health. When even young healthy adults eat “junk” foods, aspects of cognition linked to the hippocampus quickly decline.

    On the other hand, research shows a diet containing more and varied plant foods and seafood … leads to better cognitive performance. This study was conducted in a closed chamber for 45 days, designed to mimic conditions in space.

    So ensuring all astronauts have the healthiest and most diverse of microbes for the whole of the mission is vital.


    [1] Felice Jacka is the founder and director of the Food & Mood Centre at Deakin University and the founder of the International Society for Nutritional Psychiatry Research (ISNPR).

    Dorit Donoviel is Executive Director, NASA-Funded Translational (moving products from lab-bench to practice) Research Institute for Space Health at Baylor College of Medicine.

  32. Space mission mental health

    Long-term space missions pose long-term mental health issues.

    • > “Watch trailer for ‘Space: The Longest Goodbye,’ new film exploring astronaut mental health (video)” by Jeff Spry (February 18, 2024) – Follow a NASA psychologist as he trains future deep-space travelers to maintain [mental] stability on long missions.

    • YouTube > Greenwich Entertainment > “Space: The Longest Goodbye | Official Trailer” (Jan 12, 2024) – In the next decade, NASA will send astronauts to Mars for the first time. Separated from Earth, and unable to communicate with ground in real time, crew members will experience extreme isolation that could gravely affect their three-year journey. This Sundance-premiering documentary follows a savvy NASA psychologist tasked with protecting daring space explorers.

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