Why A Human Being Will Probably Not Set Foot on Mars – and Related Problems

 

I started reading science fiction about space travel when I was a kid. There was no Internet.  Television was all broadcast, grainy, and reception was shaky.  Radio was mostly focused on music.  It was decades after Orson Welles famous radio broadcast of an alien invasion that some people took as reality.  All I had was a bookmobile with a science fiction section.  I still remember the very first book I read from the bookmobile – When Worlds Collide.  By the sixth grade I was writing 3-page science fiction stories myself - largely based on our class following the early space flights.

Over the decades science fiction about space travel progressed significantly. Even though humans made clear progress – it was nowhere near the fictional travels to deep space, federations of planets, and routine interaction with alien life forms. After a brief concern about an invasion by Martians, the more practical sci-fi has focused on travel to and colonization of Mars.  Just focused on Mars the stories have become more realistic from a booming future colony on Mars to a survival film of a solo astronaut on Mars.

Science fiction and fantasies about space travel have moved squarely outside of science fiction and the cinema these days.  They are influencing how billions of dollars are being spent on Wall Street.  Elon Musk has clearly stated that he intends to send a mission to Mars for the express purpose of colonizing it.  He has given several dates for his first Mars mission that have come and gone.  He has modified his statement several times so that it now includes taking human consciousness extraplanetary.  He also has framed this endeavor as a necessary move to save humanity. This post is all about why that will probably not happen and why all of that rhetoric needs to be rejected outright.

From a science perspective and in a single word it comes down the severe biomedical burden of space travel and the ability of humans to protect themselves against these dangers.  The suggested colonization and possible terraforming of Mars (modifying the atmosphere, temperature, and surface to support human life) also creates a massive resource burden on the Earth and its inhabitants.  This post will examine some of those details and whether or not they have been technically solved. 

At first glance Earth and Mars, Earth is an average of 93 million miles from the Sun and Mars is 142 million miles.  Earth is 7,926 miles in diameter compared with Mars at 4,212 miles.  Gravitation on Mars is 38% of what it Is in Earth (acceleration due to gravity = 3.72 m/s² compared to 9.82 m/s²).  Martian soil is toxic in that it contains perchlorates, silica and various heavy metals.  Martian soil has been studied as both regolith (planetary cover) and dust.  Martian dust has a particle size of 3 microns and is composed of silicon (Si), magnesium (Mg), and iron (Fe).  Based on previous experience with lunar dust it is likely that Martian dust will be a common contaminant.  In addition, the soil contains perchlorate compounds (ClO₄^- )  that can alter thyroid function and cause aplastic anemia.  A variety of illnesses can be produced by this dust including pulmonary, gastrointestinal, endocrine, and neurological diseases (see table1, Reference 1). Perchlorate is also a significant contaminant of water on Mars.  There is no free groundwater but water exists frozen under the surface and has been suggested as a source of water for drinking and terraforming.  Several very limited plant experiments have been done with soil simulating Martian soil.  They are typically limited by species tested and no complete match for soil.  An example is that I have not seen is a paper that tests soil containing perchlorate. Plans to extract water from frozen underground glaciers that also contain perchlorate are also not available.

Apart from the soil and water problem there is an associated engineering problem to provide food both for the flight to Mars and post arrival.  For flights all of most of the food would need to be pre-packaged largely because of the large area needed to grow food to feed people.  This is an interesting engineering problem that NASA has been working on for at least 30 years. In order to grow plants for food on Mars it will take a highly controlled environment (pressure, temperature, atmosphere, radiation protection, lighting and irrigation requirements).  These requirements and the rationale are listed in the table below.   

Requirement	Primary Function / Purpose	Key Operational Challenge / Engineering Need
Atmospheric Pressurization	Keeps water liquid inside plant tissues; enables respiration and photosynthesis.	Must maintain >100-150 mbar of internal pressure against Mars' near-vacuum surface (~6.1 mbar).
Climate & Thermal Control	Protects crops from extreme cold (averaging -60 C); maintains optimal growth temperatures.	Requires heavy thermal insulation, active heating systems, and automated humidity control.
Radiation Shielding	Prevents DNA damage, mutations, and cell degradation from Galactic Cosmic Rays (GCRs) and Solar Particle Events (SPEs).	Enclosure must be buried under several meters of regolith, water layers, or placed inside lava tubes.
Substrate & Water Purification	Removes toxic perchlorates (0.5-1%) and heavy metals; provides a clean growing medium.	Requires chemical leaching/flushing of regolith, or multi-stage filtration and reverse osmosis for harvested subsurface ice.  May require long distance transport of ice
Supplemental Spectrum Lighting	Offsets weak Martian solar irradiance (43% of Earth's) and dust storm dimming; drives photosynthesis.	Requires high-efficiency PAR LED arrays, creating a high, continuous electrical power demand.
Buffer Gas Delivery (N2/Ar)	Dilutes CO2 and O2 to prevent atmospheric toxicity, metabolic collapse, and fire hazards.	Requires cryogenic processing units to extract and concentrate sparse atmospheric nitrogen (~2.6% of Mars' air).
Micro-Ecological Inoculation	Provides essential soil microbiomes (nitrogen-fixing bacteria, mycorrhizal fungi) and ensures crop pollination.	Substrates must be manually seeded with bio-engineered microbe cultures; requires mechanical or automated pollinators.
Closed-Loop Waste Recycling	Recovers nitrogen, phosphorus, and potassium (NPK); recycles non-edible crop biomass and grey/blackwater.	Requires onboard bioreactors, composting, or supercritical water oxidation to maintain nutrient cycles without Earth resupply.
Sensors & Pathogen Control	Prevents catastrophic crop loss from fungal spores, viral blights, or gas imbalances in an isolated ecosystem.	Demands continuous HEPA/UV-C air sterilization and automated real-time multispectral monitoring.

 

As noted, the food growing on Mars will require significant electrical energy requirements to design, construct, and maintain the food growing environment.  Controlled growing experiments by both NASA and Russian programs based on the estimate of 2,500 cal/day for each human suggests that 50-100 m² is the required growing area for a combination of plants that will supply the necessary carbohydrates and proteins.  For a relatively small colony of 1,000 people that would translate to 65-100,000 m². An American football field is 7,140 m2 so at the max this would be about 14 football fields in size.  Some Mars promoters have suggested the size of this colony should be 100,000 people.  That would be 247 acres or 0.39 square miles just for food production.

To reduce the size of this facility it would probably be built vertically in 4-6 layers to reduce the ground level footprint to 16-25,000 m².  That would contain 300-500,000 m³ of pressurized air to maintain climate control, humidity, and gas exchange (20-25 m² of crops under optimal lighting produces enough oxygen for 1 person).  Additional engineering requirements would be 360-720 megawatt hours (MWh) of electric power per day, a continuous circulating loop of 5-10 million liters of pure water, and a one-time structural fill volume of 300-500 metric tons of nitrogen.  This is an unprecedented engineering challenge.  Even if it were clear that water could be purified and extracted from Martian ice and nitrogen could be produced from the thin atmosphere all of the initial equipment would all have to be sent from Earth.  That would take 15-30 heavy lift launches to produce a structure of unknown durability and maintenance needs.  There is no room for error given the flight time from Earth of 180 days for resupply.    

The atmosphere on Mars is a more immediate problem than the soil and all of the construction work would need to occur in that atmosphere. A good comparison is seen in the infographic below from the European Space Agency.  Needless to say – the Martian atmosphere as it stands in not compatible with human life.  Living quarters and suits would need to be as climate and atmosphere controlled as food growing areas.

 

A hidden danger that has flown under the radar for some time is radiation risk. The tables below show the actual measured radiation exposure to Apollo astronauts by physical dosimeters.  The Mars estimates were also physically measured in unmanned spacecraft.     

Apollo Crew Radiation Exposure
Mission	Flight Duration	Lunar Surface Time	Average Radiation Dose
Apollo 11	8 days, 3 hrs	21 hrs, 38 mins	1.8 mSv
Apollo 12	10 days, 4 hrs	31 hrs, 31 mins	5.8 mSv
Apollo 14	9 days, 0 hrs	33 hrs, 31 mins	11.4 mSv
Apollo 15	10 days, 1 hr	66 hrs, 54 mins	3.0 mSv
Apollo 16	11 days, 1 hr	71 hrs, 02 mins	5.1 mSv
Apollo 17	12 days, 13 hrs	74 hrs, 59 mins	5.5 mSv

 

Mars Mission Radiation Exposure
Mission Phase	Estimated Duration	Daily Exposure Rate	Phase Total Dose
Transit to Mars	~180 days	~1.8 mSv/day	~320 mSv
Surface Stay	~500 days	~0.64–0.67 mSv/day	~320 mSv
Return Transit	~180 days	~1.8 mSv/day	~320 mSv
Total Mission	~860 days	—	~1,000 mSv (1.0 Sv)

 A couple of radiation anchor points:  a whole-body CT scan delivers about 10 mSv as x-rays.   The NASA suggested lifetime radiation exposure was recently updated to 600 mSv.  That takes into account cancer, cardiovascular, and brain risk (Ramos).  A Mars mission as outlined above exceeds that risk.  Attempted risk mitigation would include faster transit times and burying living quarters underground/regolith on Mars.  But those variables and what could be achieved are unknown at this time.  If the radiation parameters cannot be improved due to the tradeoffs between the amount of shielding and negligible safety gains - long term colonization by the same people would seem to be an impossibility. 

The type of radiation is also important.  In space, the predominant form is galactic cosmic rays (GCRs) originating in supernovae.  GCRs consist 87% protons, 12% alpha particles, and 1% HZE heavy nuclei (Z in this case refers to the atomic number or number of protons) so it can be read as high atomic number and energy. Comparing GCRs to other common forms of radiation show that it is at the level of 100 MeV to over 1,000,000 MeV (10⁸ to 10¹² eV.  A single GCR proton or heavy ion carries 1,000 to over 10,000,000 times more energy than a typical gamma ray.  The physical properties of the radiation also dictate the shielding requirements. X-rays and gamma rays can use high Z materials like lead (Pb) with a lot of electron density.  GCRs must use low Z materials like water or polyethylene with a lot of hydrogen density to prevent secondary neutrons produced from spallation when HZE nuclei hit large nuclei in shielding. That can lead o a tradeoff of space occupied by the shielding volume and the inevitability that some fraction of high energy particles will go through.

GCR is about 85% of the expected radiation burden followed by transient solar flare radiation (10-15%), and background gamma radiation.  The engineering tradeoffs depend on context (flight versus landed), physical properties of the radiation, extra fuel and thrust necessary for the flight, predictability of radiation bursts, and in some cases power requirements in flight.  Unless there is literature I have not accessed, the estimates of total radiation exposure would seem prohibitive for any long-term settlement of the planet.  It is estimated it would require 1-2 meters of regolith over and inflatable structure to drop the GCR and secondary neutron flux down to acceptable levels on Mars.  Even a deep under regolith settlement still has major logistic problems in getting access to purified water, nitrogen for atmospheric stabilization, HVAC for temp and humidity regulation, and the power to run it all. 

The drain on Earth resources has already begun even before the first manned Mars launch.  SpaceX has as one of its funding sources the Starlink satellite system.  Starlink was designed as low altitude satellite system to provide Internet access in areas with no cable or fiber optic access. The low altitudes are necessary to reduce transmission latency necessary to real time communication. Because of the low altitudes and the curvature of the Earth, thousands of networked satellites are necessary.  An estimated 11,110 functioning satellites are currently in low Earth orbit (LEO).  Six hundred to a thousand of these satellites fall out of orbit each year (1-3 per day) burning up in the atmosphere. 

In 2026 there will be 100-110 Starlink satellites launched to replace the satellites falling out of orbit.  Future projections are for 4 to 5 satellites re-entering every day—or 1,500 to 1,800+ satellites falling out of orbit every year.  SpaceX has 2 rockets to replace these satellites – the Falcon 9 that can carry up to 24 satellites and the Starship that can carry up to 60 satellites.

The environmental burden is significant.  Each Falcon 9 launch injects soot into the upper atmosphere where it remains much longer than on Earth (3-5 years). That soot absorbs solar radiation and has a 500-fold warming impact on the planet compared with ground level soot.  As the satellites reenter and burn up aluminum oxide nanoparticles are generated increasing the risk of ozone depletion and potentially reflect or absorb incoming solar radiation.

All things considered, the information I can find on the planned expedition and colonization of Mars has numerous red flags.  The bottom line is that it is a massive engineering undertaking that presents a significant risk to anyone willing to take a trip to Mars.  I highlighted some of the main risks here but there are many additional details including a paper written about how to treat radiation sickness during the flight. I did not touch on the background effects of weightlessness and the associated syndromes.  They are significant and require physical training effort to minimize. Any routine illness in space will not be the same routine illness that would have happened on Earth.

And the question is – to what end?  Are we really expanding human consciousness into the cosmos – or sending it to a miserable demise? Is staying on Earth putting all of our survival eggs in one basket or is it the best rationale decision to keep us alive?  And what about the conflict-of-interest issues. The space business is no longer a government enterprise carrying forth the aspirations of mankind.  It is a multibillion-dollar, for-profit, publicly held enterprise.  The colonization of Mars is estimated to cost over a trillion dollars.   That is heavy financial incentive for hyping space travel and ignoring the current significant environmental costs that are now funding it. 

I have done a significant amount of research on the extraterrestrial issue and debated another long post on that topic but I will cut to the chase here instead.  There is no evidence that Earth has ever been visited by extraterrestrial beings.  The distances are too great, and the recorded aerial phenomena too weak to consider as evidence. That does not mean there are not other intelligent life forms out there – only that if there are - they have not visited Earth.

Planet	Mean Surface / Effective Temp (°C)	Mean Surface / Effective Temp (°F)	"Surface" Definition
Mercury	167 °C	333 °F	Surface varies wildly: -180 °C (-290 °F) at night to 430 °C (800 °F) by day.
Venus	464 °C	867 °F	Solid surface; runaway greenhouse effect creates a uniform, scorched temperature.
Earth	15 °C	59 °F	Solid surface.
Mars	-65 °C	-85 °F	Solid surface; thin atmosphere causes large swings (-125 °C to 20 °C).
Jupiter	-110 °C	-166 °F	Measured at 1 bar pressure level (no solid surface).
Saturn	-140 °C	-220 °F	Measured at 1 bar pressure level (no solid surface).
Uranus	-195 °C	-320 °F	Gas of atmosphere transitions into a thick, fluid interior without a clear boundary or solid ground.  Measured at 1 bar pressure level; drops as low as -224 °C (-371 °F) in the upper atmosphere.
Neptune	-200 °C	-330 °F	Measured at 1 bar pressure level (no solid surface).

 

Just looking at planet surface temperature and their increasing distance from the sun it seems obvious why Earth is the only non-hostile environment for humans.  All of the hype about “expanding human consciousness to the universe” or “a humanitarian argument for making life multi-planetary”, or that it is “too risky to put all of our eggs in one basket” – is just that.  As far as preserving Earth goes – I can’t say it any better than Carl Sagan:

“It has been said that astronomy is a humbling and character-building experience. There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly with one another, and to preserve and cherish the pale blue dot, the only home we've ever known.”

— Carl Sagan, Pale Blue Dot, 1994

Be more like Carl Sagan and less like the legion of politicians and entrepreneurs destroying the only home we will ever know.         

  

George Dawson, MD, DFAPA 

Supplementary 1.  Radiation Risk from Standard X-rays: I thought I would add an explanatory paragraph on radiation exposure in space and dosing compared to standard x-rays.  Recall that x-rays are photons and galactic cosmic ray (GCRs) are particles.  It is calculated from the absorbed dose in Gy (where 1 Gy = 1 J/kg).  That absorbed dose is multiplied by organ and tissue weighting factors to reflect the potential for injury.  For radiation in space Linear Energy Transfer (LET) of high energy particles is used for the exposure calculation (1).  That equation is:

H = D × Q ,

where D = (physical energy deposition) absorbed dose in energy per unit mass.

Q = quality factor - continuous function of the particle's linear energy transfer (LET), ranging from 1 for low-LET radiation (photons, fast protons) up to ~30 for densely ionizing heavy ions. There are 2 competing models for Q.

H = (risk relevant biological dose) dose equivalent of biologically equivalent dose (mSv).

 

The important concept in looking at equivalent radiation doses between photons (x-rays, gamma rays) and particles (GCRs) is that GCRs are not directly measured and are estimates based on both the 2 models of the Q factor and the particle composition of the radiation. The HZE particles that drive the radiation dose in space for astronauts are elements 2 (Helium or He) to 26 (Iron or Fe).

In the simpler case on Earth, medical x-rays have been studied.  Several of those studies show a higher risk of malignancy with more x-ray exposure. The table below gives the effective dose and dose relative to background radiation (on Earth) for a number of procedures.  Longer procedures like CT scans and fluoroscopy have higher radiation exposure.  Compare to Mars Mission Radiation Exposure (3rd table above).

 

Modality / study	Typical effective dose (mSv)	Multiple of a chest X-ray / background	Cancer-risk context	References
Chest radiograph (PA)	0.02	1× (baseline)	Negligible; pediatric attributable risk <1%	[2, 3]
Panoramic/intraoral dental	0.01	~0.5×	Negligible	[2, 4]
Mammography	0.4	~20×	Very low	[2, 4]
Lumbar spine (3 views)	1.5	~75×	Low	[2]
CT head	~2	~100×; ~2/3 of annual background	Bone-marrow dose ~13.7 mGy; pediatric RR ~1.35 for hematologic cancer	[1-3]
CT chest	7 (range 5–13)	~350×; ~2 yr background	Small individual stochastic risk	[1-2, 5]
CT abdomen/pelvis	14 (range 10–17)	~700×	One of the higher routine CT doses	[2, 5]
CT pulmonary embolism protocol	15	~750×	Higher because multiphase	[2]
Multiphase / combined CAP CT	~30–40 (cumulative)	approaching detectable-risk threshold with repetition	~1 in 100 lifetime cancer per 100 mSv (BEIR VII)	[2, 5]
Nuclear stress test (sestamibi 1-day)	9.4	~470×	Moderate	[2]
Nuclear stress test (thallium)	40.7	~2,000×	Among the highest routine studies	[2]
Diagnostic cardiac catheterization	7	~350×	Operator- and case-dependent	[2]
Coronary stent / PCI	15	~750×	Higher with complexity	[2]
Interventional/fluoroscopic procedures (range)	5–70 (up to >250 for portography)	highly variable	Skin injury threshold at ~5 Gy air kerma triggers follow-up	[1, 6]
1.  Mettler FA Jr, Huda W, Yoshizumi TT, Mahesh M. Effective doses in radiology and diagnostic nuclear medicine: a catalog. Radiology. 2008 Jul;248(1):254-63. doi: 10.1148/radiol.2481071451. PMID: 18566177. 2.  Ford B, Dore M, Moullet P. Diagnostic Imaging: Appropriate and Safe Use. Am Fam Physician. 2021 Jan 1;103(1):42-50. PMID: 33382559. 3.  Smith-Bindman R, Alber SA, Kwan ML, et al. Medical Imaging and Pediatric and Adolescent Hematologic Cancer Risk. N Engl J Med. 2025 Oct 2;393(13):1269-1278. doi: 10.1056/NEJMoa2502098. Epub 2025 Sep 17. PMID: 40961449; PMCID: PMC12445590. 4.  Ahmed NA. Typical effective dose values from diagnostic and interventional radiology. Appl Radiat Isot. 2023 Feb;192:110611. doi: 10.1016/j.apradiso.2022.110611. Epub 2022 Dec 7. Erratum in: Appl Radiat Isot. 2026 Jun;232:112543. doi: 10.1016/j.apradiso.2026.112543. PMID: 36516635. 5.  Smith-Bindman R, Moghadassi M, Wilson N, Nelson et al. Radiation Doses in Consecutive CT Examinations from Five University of California Medical Centers. Radiology. 2015 Oct;277(1):134-41. doi: 10.1148/radiol.2015142728. Epub 2015 May 19. PMID: 25988262; PMCID: PMC4613871. 6.  Li X, Hirsch JA, Rehani MM, Yang K, Liu B. Effective Dose Assessment for Patients Undergoing Contemporary Fluoroscopically Guided Interventional Procedures. AJR Am J Roentgenol. 2020 Jan;214(1):158-170. doi: 10.2214/AJR.19.21804. Epub 2019 Oct 31. PMID: 31670595.

 

The strongest recent human evidence comes from the 2025 NEJM cohort of 3.7 million children (3), which found a linear dose-response for hematologic cancer detectable below 50 mGy — a relative risk of ~1.8 at 15–20 mGy (roughly one to two head CTs) and ~3.6 at 50–100 mGy — estimating that 10.1% of hematologic cancers in the cohort were attributable to imaging radiation.

It is important to keep in mind that all medical risks are probabilistic and there are additional demographic factors like age, sex, and cumulative exposure and that risk always needs to be balanced against the potential benefit. As an example worldwide a million people each year undergo cardiac ablations for arrhythmias despite the x-ray exposure and a significant number of those people need a repeated procedure.

1:  Naito, M., Kodaira, S. Considerations for practical dose equivalent assessment of space radiation and exposure risk reduction in deep space. Sci Rep 12, 13617 (2022). https://doi.org/10.1038/s41598-022-17079-1  

2:  Smith-Bindman R, Chu PW, Azman Firdaus H, et al. Projected Lifetime Cancer Risks From Current Computed Tomography Imaging. JAMA Intern Med. 2025;185(6):710–719. doi:10.1001/jamainternmed.2025.0505

3:  Smith-Bindman R, Alber SA, Kwan ML, et al. Medical Imaging and Pediatric and Adolescent Hematologic Cancer Risk. N Engl J Med. 2025 Oct 2;393(13):1269-1278. doi: 10.1056/NEJMoa2502098. Epub 2025 Sep 17. PMID: 40961449; PMCID: PMC12445590.

4:  Baerlocher MO, Detsky AS. Discussing Radiation Risks Associated With CT Scans With Patients. JAMA. 2010;304(19):2170–2171. doi:10.1001/jama.2010.1591

Graphics Credit:  

1:  Planet Mars.  By Sevinchalisherovna, CC BY-SA 4.0 https://creativecommons.org/licenses/by-sa/4.0 Unaltered.

2:  Comparison of the Mars and Earth atmospheres is from the European Space Agency ©ESA and it is used here per Common Cause license (see link for details) CC BY-SA 3.0 IGO  It is unaltered and this is a non-commercial and not-for-profit site.

 

References:

1:  Wang, J. L., Rosenbaum, J. J., Prasad, A. N., Raad, R. R., Putman, E. J., Harrington, A. D., et al. (2025). Potential health impacts, treatments, and countermeasures of martian dust on future human space exploration. GeoHealth, 9, e2024GH001213. https://doi.org/10.1029/2024GH001213

2:  Caston, R., Luc, K., Hendrix, D., Hurowitz, J. A., & Demple, B. (2018). Assessing toxicity and nuclear and mitochondrial DNA damage caused by exposure of mammalian cells to lunar regolith simulants. GeoHealth, 2, 139–148. https://doi.org/10.1002/2017GH000125

3:  Kasiviswanathan P, Swanner ED, Halverson LJ, Vijayapalani P. Farming on Mars: Treatment of basaltic regolith soil and briny water simulants sustains plant growth. PLoS One. 2022 Aug 17;17(8):e0272209. doi: 10.1371/journal.pone.0272209. PMID: 35976812; PMCID: PMC9385024.

4:  Cucinotta FA, Kim MH, Chappell LJ, Huff JL. How safe is safe enough? Radiation risk for a human mission to Mars. PLoS One. 2013 Oct 16;8(10):e74988. doi: 10.1371/journal.pone.0074988. PMID: 24146746; PMCID: PMC3797711.

5:  Brojakowska A, Bisserier M, Eskandari A, Jagana V, Khlgatian MK, Arakelyan A, Fogarty J, Kovacic JC, Goukassian DA. Cardiovascular risks and hazards associated with deep space exploration. Commun Med (Lond). 2026 Jun 23;6(1):354. doi: 10.1038/s43856-026-01728-x. PMID: 42337079; PMCID: PMC13291221.

6:  Narici, L., Baiocco, G., Cenci, G. et al. Radiation risk mitigation in human space exploration: a primer, a vision, and the state of the art. Eur. Phys. J. Plus 141, 100 (2026). https://doi.org/10.1140/epjp/s13360-025-07199-8

7:  Patel, Z.S., Brunstetter, T.J., Tarver, W.J. et al. Red risks for a journey to the red planet: The highest priority human health risks for a mission to Mars. npj Microgravity 6, 33 (2020). https://doi.org/10.1038/s41526-020-00124-6

8:  Fogtman A, Baatout S, Baselet B, Berger T, Hellweg CE, Jiggens P, La Tessa C, Narici L, Nieminen P, Sabatier L, Santin G, Schneider U, Straube U, Tabury K, Tinganelli W, Walsh L, Durante M. Towards sustainable human space exploration-priorities for radiation research to quantify and mitigate radiation risks. NPJ Microgravity. 2023 Jan 27;9(1):8. doi: 10.1038/s41526-023-00262-7. PMID: 36707520; PMCID: PMC9883222.

9:  Kernagis DN, Balcer-Kubiczek E, Bazyar S, Orschell CM, Jackson IL. Medical countermeasures for the hematopoietic-subsyndrome of acute radiation syndrome in space. Life Sci Space Res (Amst). 2022 Nov;35:36-43. doi: 10.1016/j.lssr.2022.06.002. Epub 2022 Jun 9. PMID: 36336367.

10:  Ewert, M. K., Chen, T. T., & Powell, C. D. (2022). Life support baseline values and assumptions document (Report No. NASA/TP-2015-218570/REV2). NASA Johnson Space Center.  https://ntrs.nasa.gov/api/citations/20210024855/downloads/BVAD_2.15.22-final.pdf

11:  Monje, O., Stutte, G. W., Goins, G. D., Porterfield, D. M., & Bingham, G. E. (2003). Farming in space: Environmental and biophysical concerns. Advances in Space Research, 31(1), 151–167. https://doi.org/10.1016/s0273-1177(02)00751-2   Abstract at:  https://pubmed.ncbi.nlm.nih.gov/12577999/

12:  Wheeler, R. M. (2020). NASA’s contributions to vertical farming (Report No. NASA TM-2020-5008832). NASA Kennedy Space Center.  https://ntrs.nasa.gov/api/citations/20205008832/downloads/NASA%20TM-2020-5008832%20NASA's%20Contributions%20to%20Vertical%20Farming.pdf

13:  Wheeler, R. M., Mackowiak, C. L., Stutte, G. W., Sager, J. C., Yorio, N. C., Ruffe, L. M., Fortson, R. E., Dreschel, T. W., Knott, W. M., & Corey, K. A. (1996). NASA's Biomass Production Chamber: A testbed for bioregenerative life support studies. Advances in Space Research, 18(4–5), 215–224. https://www.sciencedirect.com/science/article/abs/pii/027311779500880N?via%3Dihub

 14:  Monje, O., Stutte, G. W., Goins, G. D., Porterfield, D. M., & Bingham, G. E. (2003). Farming in space: Environmental and biophysical concerns. Advances in Space Research, 31(1), 151–167. https://doi.org/10.1016/s0273-1177(02)00751-2

15:  Ramos RL, Carante MP, Ferrari A, Sala P, Vercesi V, Ballarini F. A Mission to Mars: Prediction of GCR Doses and Comparison with Astronaut Dose Limits. Int J Mol Sci. 2023 Jan 24;24(3):2328. doi: 10.3390/ijms24032328. PMID: 36768652; PMCID: PMC9916691.