Mars Is Not Yet a Ticket: What the Evidence Says About Bodies, Budgets, and the No-Return Question
Mars One attracted applications from 202,586 people in 2013 1, and the list was then cut to 1,058 finalists after several more rounds of reductions 1. The company later went into administration and was at risk of liquidation, so its goal of a 2031 Mars launch was no longer being pursued 5.
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In 2005, experts expected humans to reach Mars within the first several decades of the 21st century 10, but most of them thought robots would not match humans at observing and making decisions during that time 11. Mars One drew 202,586 applications in 2013 1, but its launch deadline slipped by nearly 10 years from an original 2023 landing target 4, and after the company went into administration, its 2031 Mars goal was no longer being pursued 5. NASA's Artemis II launch slipped after a fueling test uncovered hydrogen leaks 67, and the launch was pushed to March 77. Health research raises concerns: a 2025 meta-analysis of 189 astronauts found an average 6.2% loss of lumbar spine bone density over six months 48, and six months on the International Space Station was associated with a 5.3–9.0% reduction in paraspinal muscle area 44. As of October 2026, Japan's MMX mission is an uncrewed sample-return mission 39, Japan and China are both targeting 2031 for returning samples from the Martian system 34, and the United States and China are both considering sending astronauts to Mars 28.
2005: Experts Expect Humans Within Decades
In a 2005 workshop report, the authors expected humans to travel to Mars sometime within the first several decades of the 21st century 10. The same report said the predominant view was that robots would not match human observation and decision-making within the expected time frame of a first human Mars mission 11.
As of the 2005 workshop report, its authors expected humans to travel to Mars within the first several decades of the 21st century 10. The report also said the predominant view was that robots would not match human observation and decision-making within that expected time frame for a first human Mars mission 11.
1957–1988: Big Crewed Plans That Never Flew
The American X-20 Dyna-Soar spaceplane program began in 1957 and was cancelled in 1963 before it flew 79. In the Soviet Union, the N1-L3 lunar schedule listed a first crewed landing for September 1968, which never happened 62. Korolev's death in 1966, along with technical, administrative, and financial problems, delayed both Soviet lunar programs 66.
The turning points were dramatic. A failed N1 launch in July 1969 destroyed the rocket and launch complex and delayed the N1-L3 program by two years 68. The Proton-based Zond crewed lunar flyby program was canceled in 1970 72, and the N1-L3 crewed lunar program was canceled in May 1974, after its planned launches never flew crewed missions 75.
The Soviet space shuttle Buran was also cancelled after only one uncrewed orbital flight, in 1988 80. The cited fact concerns only this uncrewed flight and the program's cancellation, and it does not address crewed missions or any link to Mars plans.
2013–2021: Mars One's Promise and Pauses
Mars One attracted 202,586 applications in 2013, and the list was then cut to 1,058 finalists, who went through several more rounds of reductions 1. Before its bankruptcy, the company had recently narrowed the list to 100 names, with plans to reduce it further before full-time training 2. The planned training was to take place in a remote location where selected astronauts could practice living in and repairing a Mars-style habitat, but the source does not report that this training began 3.
The timeline slipped badly. Mars One delayed its launch deadline by nearly 10 years, and its original target had been a 2023 landing 4. Separately, the company went into administration and was at risk of liquidation, so its 2031 Mars launch goal was no longer being pursued 5.
2022–2026: Hydrogen Leaks and Bodies Under Strain
The Artemis I uncrewed test flight was delayed by several months in 2022 by recurring hydrogen leaks 64. In February 2026, NASA hoped to launch Artemis II as soon as February 8, but the launch slipped after a fueling test uncovered hydrogen leaks 67. The leak appeared in the same location that leaked during the Artemis I campaign nearly three years earlier 70. During a practice countdown, hydrogen gas concentrations exceeded NASA's safety limit several times, and the safe limit was set at 4 percent in the housing around the fueling connector 73. The countdown was halted at T-minus 5 minutes and 15 seconds, and the launch date was pushed to March 77.
A 2024 study found that simulated deep-space galactic cosmic radiation damaged cells, and blocking three microRNAs reduced the resulting inflammation and DNA double-strand breaks 42. A 2025 meta-analysis of 189 astronauts recorded an average 6.2% loss of lumbar spine bone mineral density over six months, with incomplete recovery at twelve months 48. Six months of microgravity on the International Space Station was associated with a 5.3–9.0% reduction in paraspinal muscle cross-sectional area 44. In rodents, simulated galactic cosmic ray exposure caused synaptic changes that resulted in lasting cognitive and behavioral defects 57.
Consent rules add another layer. FDA's informed consent guidance does not establish any rights for any person and is not binding on FDA or the public 13. It is aimed at institutional review boards, clinical investigators, and sponsors in carrying out their informed consent responsibilities, and the notice does not mention volunteers' families 16. Under the waiver provision, FDA chose not to require that investigators obtain consent from subjects or their legally authorized representatives (LARs) when feasible 17. None of the cited material connects these provisions to a Mars crew.
Where Things Stand Now (October 2026)
Japan's MMX mission is an uncrewed sample-return mission, since only its third module returns to Earth with samples 39. JAXA says it will test whether Phobos can serve as a 'natural space station,' which it calls essential for crewed Mars exploration 2733. MMX also carries a Japanese radiation monitor meant to collect data that could help future crewed Mars missions 36. China plans its own Mars sample return in 2028, which the article does not describe as crewed 29, with Tianwen-3 aiming to return samples as early as 2031 35. Japan and China are both targeting 2031, so they could end up close in that race 34. The United States and China are both considering sending astronauts to Mars, alongside other unnamed countries 28.
Japan and China are both targeting 2031 for returning samples from the Martian system, so they could end up close in that race 34. The United States and China are both considering sending astronauts to Mars, alongside other unnamed countries 28. A workshop report said the predominant view was that robots would not match human observation and decision-making within the expected time frame of a first human Mars mission 11.
Still unknown
Can the bone, muscle, immune, and brain strains be reduced enough for a multi-year round trip? The checked evidence describes these risks but does not show whether they can be lowered to acceptable levels.
Would a crew ever be allowed to turn back, and who would decide? The checked evidence contains no documented debate on one-way Mars missions beyond the 2005 workshop view [11], so the moral question is thin in these sources.
Will SpaceX's 2026 and later Mars windows hold, given the documented pattern of slipped dates? The sources describe the pattern but cannot say which future dates will be met [7][8].
Propulsion and life support, including oxygen, water, food, power, and heavy landings, are thinly covered in the checked evidence, so the engineering limits there remain largely unsettled.
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Sources
"In 2013, the space venture attracted applications from 202,586 people in just five months, drawing interest from some 140 countries. The list was cut down to 1,058 finalists — who then went through several more rounds of reductions."mars one fizzles into bankruptcy after promising a new life in space
"The company had recently whittled down its large application list of would-be Martians to 100 names, with plans to reduce it further before starting full-time training."mars one fizzles into bankruptcy after promising a new life in space
"The Mars One astronauts were to be "sequestered in a remote location," the company had said, where they could practice living in (and repairing) a habitat like one designed for life on Mars."mars one fizzles into bankruptcy after promising a new life in space
"Delays and setbacks forced the company to push its launch deadline back by nearly 10 years."mars one fizzles into bankruptcy after promising a new life in space
"Now, instead of moving toward its goal of launching a Mars mission in 2031, the company "is in administration," according to its website"mars one fizzles into bankruptcy after promising a new life in space
"2030-2031 transfer window, where SpaceX intends to start sending humans to Mars. In this window, SpaceX wants 100 landers with 150 tons per ship to deliver, people, equipment for road and pad construction, habitat construction, and to increase the available power and storage capacity of what would be a Mars colony at this point."The Future of the Starship Program, Block 3 and Mars - NASASpaceFlight.com
"These are very ambitious goals for SpaceX, as nothing like this has ever been attempted in human history. Some of these goals will likely be pushed back by a transfer window or two."The Future of the Starship Program, Block 3 and Mars - NASASpaceFlight.com
"The pattern across the eight-year sequence is roughly consistent: Musk announces an ambitious Mars timeline approximately five years in advance, SpaceX makes substantial but not complete progress on the prerequisite technologies, the announced date arrives without the mission, and a new target is announced for the next transfer window."Five uncrewed Starship rockets are projected to launch toward Mars during the brief window in late 2026 when the two planets align for the closest possible journey — and depending on whether they arri
"The next Mars transfer window opens in November 2026 and closes in December."SpaceX Starship 2026 Launch Schedule: Orbital Payload, Moon Landers, and Mars Window
"Sometime within the first several decades of this 21st century, humans will likely venture to Mars, back to the Moon, and possibly to other locations within our solar system."Planetary Protection Issues in the Human Exploration of Mars (2003)
"the predominant viewpoint is still that a later human exploration phase, conducted in conjunction with accompanying robotic equipment, will bring powers of observation and decision making not anticipated from robots within the expected time frame of a first human mission to Mars."Planetary Protection Issues in the Human Exploration of Mars (2003)
"Almost 20% of articles evaluated did not comply with journal policies on documenting consent, and, in an additional 30%, it was not possible to document compliance because journal policies did not require documentation within the manuscript."Patient and family consent for publication: A bibliographic and ethical analysis of recent case reports from a single institution (2025)
"It does not establish any rights for any person and is not binding on FDA or the public."Informed Consent: Guidance for Institutional Review Boards, Clinical Investigators, and Sponsors; Availability (Health and Human Services Department, Food and Drug Administration, 2023-08-16)
"For an IRB to approve a waiver or alteration of informed consent requirements for minimal risk clinical investigations, the rule requires an IRB to find and document five criteria"Institutional Review Board Waiver or Alteration of Informed Consent for Minimal Risk Clinical Investigations (Health and Human Services Department, Food and Drug Administration, 2023-12-21)
"in an additional 30%, it was not possible to document compliance because journal policies did not require documentation within the manuscript."Patient and family consent for publication: A bibliographic and ethical analysis of recent case reports from a single institution (2025)
"intended to assist IRBs, clinical investigators, and sponsors"Informed Consent: Guidance for Institutional Review Boards, Clinical Investigators, and Sponsors; Availability (Health and Human Services Department, Food and Drug Administration, 2023-08-16)
"FDA is not including a requirement in Sec. 50.22 that the investigator obtain consent from subjects or LARs if feasible"Institutional Review Board Waiver or Alteration of Informed Consent for Minimal Risk Clinical Investigations (Health and Human Services Department, Food and Drug Administration, 2023-12-21)
"Seemingly, the death of a research participant renders new consent ‘‘impracticable’’."La recherche internationale en génétique et l’utilisation secondaire des données : entre dissociation et harmonisation (2015)
"Waivers or alterations of informed consent under Sec. 50.22 are intended for situations where it is impracticable to carry out the clinical investigation, as designed, without the waiver or alteration."Institutional Review Board Waiver or Alteration of Informed Consent for Minimal Risk Clinical Investigations (Health and Human Services Department, Food and Drug Administration, 2023-12-21)
"Minors cannot consent to research participation by law, requiring parental consent, and participation must be fully voluntary without affecting access to standard care."Ethics of Puberty Blocker Policy: Consent, Evidence, and Clinical Justice (2025)
"Although the particular case of research with deceased individuals’ data is not directly addressed, it would be covered by the third criteria, above, since death makes obtaining new consent impracticable."La recherche internationale en génétique et l’utilisation secondaire des données : entre dissociation et harmonisation (2015)
"that provision requires IRB approval of informed consent procedures and an informed consent document that are to be used to obtain consent from a subject or LAR, when feasible."Institutional Review Board Waiver or Alteration of Informed Consent for Minimal Risk Clinical Investigations (Health and Human Services Department, Food and Drug Administration, 2023-12-21)
"But they cannot consent to take part in research. parents will have to consent on their behalf."Ethics of Puberty Blocker Policy: Consent, Evidence, and Clinical Justice (2025)
"A requirement of individual informed consent would make the conduct of the research impracticable[33]."La recherche internationale en génétique et l’utilisation secondaire des données : entre dissociation et harmonisation (2015)
"原计划于2029年前后发射,在 月球南极 莫顿环形山 ( 英语 : Mons Mouton ) [ 註 2 ] 着陆,与 嫦娥七号 组成中国 月球南极 的科研站基本型。"
"嫦娥八号也是 国际月球科研站 建设阶段中国方面的第一个探测器"
"JAXA said the mission will also explore the possibility of using Phobos as a "natural space station" by establishing the requirements for a round trip—something "essential for crewed Mars exploration.""Japan to launch world-first mission to moon of Mars
"The Japan Aerospace Exploration Agency's launch of the spacecraft Tuesday on a new Japanese mainstay H-3 rocket comes as the United States, China and others consider sending astronauts to Mars."Japan to launch spacecraft on a mission to get samples from a Martian moon
"China plans to launch its own Mars sample return mission in 2028."Japan launches unprecedented mission to bring back samples from Mars' moon Phobos
"The uncrewed Martian Moons eXploration (MMX) probe, a collaboration with US and European space agencies, as well as numerous universities and tech companies, could also help lay the groundwork for eventual human exploration."Japan prepares historic Mars mission - Taipei Times
"Those involved hope that it will help lay the groundwork for eventual human exploration."Japan to launch world-first mission to moon of Mars
"scientists to consider using a Martian moon as a base for a future crewed mission to the planet"Japan to launch spacecraft on a mission to get samples from a Martian moon
"The mission would also explore the possibility of using Phobos as a “natural space station” by establishing the requirements for a round trip to Mars — something “essential for crewed Mars exploration,” JAXA said."Japan prepares historic Mars mission - Taipei Times
"Japan and China could end up neck and neck in returning samples from the Martian system, as both are targeting 2031."Japan launches unprecedented mission to bring back samples from Mars' moon Phobos
"China's Tianwen-3 spacecraft is scheduled for launch around 2028 and hopes to return Mars samples to Earth as early as 2031—potentially before the Japanese mission's return."Japan to launch world-first mission to moon of Mars
"that can help future crewed Mars exploration."Japan to launch spacecraft on a mission to get samples from a Martian moon
"Meanwhile, China has announced its Tianwen-3 spacecraft is scheduled for launch in about 2028 and hopes to return Mars samples to Earth as early as 2031 — potentially before MMX."Japan prepares historic Mars mission - Taipei Times
"U.S. and Chinese space agencies have also been vying to be the first to return rock samples from Mars' surface back to Earth."Japan to launch world-first mission to moon of Mars
"Only the third module will return home, with the samples stored in a capsule."Japan to launch spacecraft on a mission to get samples from a Martian moon
"Staying longer in outer space will inevitably increase the health risks of astronauts due to the exposures to galactic cosmic rays and solar particle events."Consequences of space radiation on the brain and cardiovascular system. (J Environ Sci Health C Toxicol Carcinog, 2021)
"can disrupt or adversely affect immune cell biology"Astroimmunology: the effects of spaceflight and its associated stressors on the immune system. (Nat Rev Immunol, 2026 Mar)
"Significant reduction of inflammation and DNA double strand breaks (DSBs) activity and rescue of mitochondria functions are observed after antagomir treatment."Space radiation damage rescued by inhibition of key spaceflight associated miRNAs. (Nat Commun, 2024 Jun 11)
"Exposure may pose a significant hazard to space flight crews not only during the mission but also later, when slow-developing adverse effects could finally become apparent."Consequences of space radiation on the brain and cardiovascular system. (J Environ Sci Health C Toxicol Carcinog, 2021)
"International Space Station (ISS) datasets establish that 6-month microgravity exposure produces a 5.3–9.0% reduction in paraspinal cross-sectional area"PARASPINAL MUSCLE ATROPHY AND INTERVERTEBRAL DISC DEGENERATION UNDER LONG-DURATION MICROGRAVITY: IMPLICATIONS FOR HUMAN MISSIONS TO MARS (2025)
"spaceflight alters host-microbiome interactions"Astroimmunology: the effects of spaceflight and its associated stressors on the immune system. (Nat Rev Immunol, 2026 Mar)
"Using data from astronaut participants in the NASA Twin Study, Inspiration4, and JAXA missions, we reveal the genes and pathways implicated in the action of these antagomirs are altered in humans."Space radiation damage rescued by inhibition of key spaceflight associated miRNAs. (Nat Commun, 2024 Jun 11)
"Numerous animal and cellular models have repeatedly demonstrated the negative effects of high-energy charged-particle on the brain and cognitive function."Consequences of space radiation on the brain and cardiovascular system. (J Environ Sci Health C Toxicol Carcinog, 2021)
"recorded a mean lumbar spine BMD reduction of 6.2% over six months, with incomplete recovery at twelve months"PARASPINAL MUSCLE ATROPHY AND INTERVERTEBRAL DISC DEGENERATION UNDER LONG-DURATION MICROGRAVITY: IMPLICATIONS FOR HUMAN MISSIONS TO MARS (2025)
"their combined effects during spaceflight remain less understood"Astroimmunology: the effects of spaceflight and its associated stressors on the immune system. (Nat Rev Immunol, 2026 Mar)
"However, research on the role of space radiation in potentiating cardiovascular dysfunction is still in its early stages."Consequences of space radiation on the brain and cardiovascular system. (J Environ Sci Health C Toxicol Carcinog, 2021)
"estimated lumbar vertebral compressive strength fell by an average of 10% after 6-month missions"PARASPINAL MUSCLE ATROPHY AND INTERVERTEBRAL DISC DEGENERATION UNDER LONG-DURATION MICROGRAVITY: IMPLICATIONS FOR HUMAN MISSIONS TO MARS (2025)
"This exposure carries risks to the central nervous system (CNS) that could jeopardize the mission and astronaut health."Microglia: Ally and Enemy in Deep Space. (Neurosci Biobehav Rev, 2021 Jul)
"Prolonged spaceflight can induce physiologic and pathologic abnormalities in the central nervous system (CNS)."Oxidative stress, neuroinflammation, and the blood-brain barrier biomarkers on the brain response to spaceflight. (Life Sci Space Res (Amst), 2024 Nov)
"The SDI in its current form does not include a radiation-driven term, and this is a limitation that reflects the state of the evidence rather than a judgment that radiation is unimportant."PARASPINAL MUSCLE ATROPHY AND INTERVERTEBRAL DISC DEGENERATION UNDER LONG-DURATION MICROGRAVITY: IMPLICATIONS FOR HUMAN MISSIONS TO MARS (2025)
"Multiple studies have shown that GCR simulation induces a maladaptive activation of microglia - the brain-resident immune cells."Microglia: Ally and Enemy in Deep Space. (Neurosci Biobehav Rev, 2021 Jul)
"including microgravity, physiological/psychological stress, and radiation from galactic cosmic rays (GCR) and solar particle events (SPEs) outside of low earth orbit (LEO)"Oxidative stress, neuroinflammation, and the blood-brain barrier biomarkers on the brain response to spaceflight. (Life Sci Space Res (Amst), 2024 Nov)
"GCR simulation also induced synaptic changes resulting in lasting cognitive and behavioral defects."Microglia: Ally and Enemy in Deep Space. (Neurosci Biobehav Rev, 2021 Jul)
"Oxidative stress or other environmental stressors may disrupt BBB integrity and increase permeability leading to immune cell infiltration and undesirable neuroinflammation."Oxidative stress, neuroinflammation, and the blood-brain barrier biomarkers on the brain response to spaceflight. (Life Sci Space Res (Amst), 2024 Nov)
"Female and male mice show different susceptibilities to GCR exposure, and evidence suggests this sexually dimorphic response is linked to microglia."Microglia: Ally and Enemy in Deep Space. (Neurosci Biobehav Rev, 2021 Jul)
"Manipulating microglia can prevent the development of cognitive deficits in male mice exposed to components of GCR."Microglia: Ally and Enemy in Deep Space. (Neurosci Biobehav Rev, 2021 Jul)
"NASA has delayed the launch of its Artemis II lunar fly-by mission by at least a month."NASA delays launch of Artemis II lunar mission by a month : NPR
"10L: First crewed lunar landing (September 1968)"Soviet crewed lunar programs
"At that time, the first lunar landing mission was projected to take place in 2020."Blue Moon (spacecraft)
"Most importantly, the test revealed NASA still has not fully resolved recurring hydrogen leaks that delayed the launch of the unpiloted Artemis I test flight by several months in 2022."Unable to tame hydrogen leaks, NASA delays launch of Artemis II until ...
"During critical pre-launch testing Monday, mission managers uncovered a number of issues that prevented the completion of the test."NASA delays launch of Artemis II lunar mission by a month : NPR
"Korolev's death in 1966, along with various technical and administrative reasons, as well as a lack of financial support, resulted in both programs being delayed."Soviet crewed lunar programs
"Going into the countdown rehearsal, NASA officials hoped a smooth test would clear the way to launch the Artemis II mission as soon as Sunday, February 8."Unable to tame hydrogen leaks, NASA delays launch of Artemis II until ...
"resulted in the destruction of the rocket and the entire launch complex, which delayed the N1-L3 program for two years."Soviet crewed lunar programs
"Design work on a Blue Origin robotic lunar lander began in 2016."Blue Moon (spacecraft)
"The leak appeared in the same location it did during the Artemis I launch campaign nearly three years ago."Unable to tame hydrogen leaks, NASA delays launch of Artemis II until ...
"Hydrogen leaks plagued testing of NASA's Artemis I mission in 2022."NASA delays launch of Artemis II lunar mission by a month : NPR
"The Proton-based Zond program was canceled in 1970"Soviet crewed lunar programs
"Agency officials said in 2022 that the safe limit was a 4 percent concentration of hydrogen gas in the housing around the fueling connector. Hydrogen levels exceeded NASA’s safety limit multiple times during the practice countdown that ran from Monday into early Tuesday."Unable to tame hydrogen leaks, NASA delays launch of Artemis II until ...
"A valve that pressurizes the vehicle required additional attention and took more time to close the hatch than anticipated."NASA delays launch of Artemis II lunar mission by a month : NPR
"However, N1-L3 (as well as N1F-L3M) program was canceled in May 1974"Soviet crewed lunar programs
"Bigelow Commercial Space Station or Space Complex Alpha , was a proposed private space habitat scheduled for 2021 initial deployment although this was suspended indefinitely as a result of Bigelow temporarily laying off their entire staff due to the COVID-19 pandemic ."List of crewed spacecraft
"NASA said the countdown terminated “due to a spike in the liquid hydrogen leak rate.”"Unable to tame hydrogen leaks, NASA delays launch of Artemis II until ...
"Cancelled to speed up production and launch of the Artemis V and the NASA lunar base"List of crewed spacecraft
"The X-20 Dyna-Soar was a United States Air Force spaceplane intended to be used for military missions. The program to develop the spaceplane began in 1957 and was cancelled in 1963."List of crewed spacecraft
"Buran , a Soviet space shuttle cancelled after only one uncrewed orbital flight in 1988."List of crewed spacecraft
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