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Body Map Explorer: How Spaceflight Affects Each Part of the Body
Also: spaceflight effects by organ · astronaut body changes
Gravity FieldsRadiationIsolation & ConfinementHostile/Closed EnvironmentCardiovascularMusculoskeletalNeuro-ophthalmicVestibular & SensorimotorBehavioral Health & SleepRenal & GUImmune & HematologicOncologyIn-flightPostflight RecoveryLEO long-durationMars transit & surfacePublicStudentClinicianResearcherOperator / Spaceflight participantAstronaut & candidate
- Weightlessness changes almost every body system: fluid shifts toward the head, balance is disrupted, and bone and muscle are lost on long missions [8][2][15]. ◆◆◆◆ High · F E
- Long missions bring eye changes (SANS) in many crewmembers and a higher kidney stone risk that lasts into the year after flight [1][18]. ◆◆◆◆ High · F E
- Radiation mainly adds long-term cancer risk; NASA caps career exposure below 600 mSv [7]. ◆◆◆◆ High · E C
Proposed certainty (◆ High → ◇ Very low) and evidence-type tags: F flight · A analog · M model/animal · C computational · E expert/operational/standards. AI-proposed, pending reviewer confirmation. How to read the grades.
Body map · select a body system
Educational only — not for clinical decisionsSimplified drawing, not to anatomical scale. The dashed outline stands for the whole body (radiation).
Eyes and brain
What happens in spaceflight
- Spaceflight associated neuro-ocular syndrome (SANS): swelling of the optic nerve head, flattening of the back of the eyeball, folds in the retina and a shift toward farsightedness on long missions. [1]
- NASA reports that about 70% of long-duration crew show at least one sign, and about 18% are diagnosed with clinically concerning SANS. [1]
What crews do about it
- Eye checks before, during and after flight, with glasses of increasing strength carried on board. [1]
- No proven preventive treatment yet. Lower-body negative pressure (suction on the lower body to pull fluid down) is under consideration, and thigh cuffs are being studied. [1]
Read more on this site
Inner ear and balance
What happens in spaceflight
- Space motion sickness (space adaptation sickness) affects most first-time flyers: NASA's medical brief gives about 73% in the first days of a first flight and 70–90% overall; an older operational brief gives 50–70%. [2][3]
- Symptoms usually resolve within about 72 hours as the brain adapts. Dizziness and unsteadiness return after landing while the brain readjusts to gravity. [2]
What crews do about it
- Medicines such as promethazine, tested on the ground before flight, and no spacewalks scheduled in the first 72 hours. [2][4]
Read more on this site
Mind and sleep
What happens in spaceflight
- Stress, depression, anxiety and relationship problems can occur. 2 of 7 NASA Shuttle–Mir astronauts (29%) reported depressive symptoms. [5]
- Sleep medicines were the most used drug class on the space station: 71% of crewmembers reported using them. [6]
What crews do about it
- Psychological selection and training, private conferences with the flight surgeon and psychologist, and attention to schedules and lighting. [5][7]
Read more on this site
Heart and blood vessels
What happens in spaceflight
- Within about 2 days in weightlessness, the body lowers its circulating blood volume by around 15%. Back in gravity, blood pools in the legs and standing up can cause light-headedness or fainting (orthostatic intolerance). [8]
- Fainting on standing is more common after long missions than short ones. [9]
- Slow or reversed blood flow in the neck (jugular) veins, and rarely a clot, has been found in flight. [10]
What crews do about it
- Exercise in flight, drinking salt water before re-entry, compression garments on the legs, and lying down after landing. [8]
Read more on this site
Lungs and spacewalks
What happens in spaceflight
- Moving from cabin pressure to a low-pressure spacesuit can release nitrogen bubbles in the body: decompression sickness ("the bends"). [11]
- NASA reports it has never had a serious (Type II) decompression sickness event in spaceflight. [11]
What crews do about it
- Breathing pure oxygen before a spacewalk (prebreathe). NASA requires protocols shown to keep the chance of decompression sickness below 4% with 95% confidence in ground testing. [11]
Read more on this site
Spine and back
What happens in spaceflight
- Back pain is common early in flight ("space adaptation back pain"). [12]
- Astronauts have a higher rate of herniated spinal discs than comparable people on Earth. [13]
What crews do about it
- After landing, NASA requires an individualized reconditioning program for each crewmember that starts at egress [V1 3017]. [7]
Read more on this site
Muscles and fitness
What happens in spaceflight
- Aerobic fitness (peak oxygen uptake) fell about 17% early in space station flights, stayed below preflight in most crew, was still low 10 days after landing, and recovered by about 30 days. [14]
What crews do about it
- Daily aerobic and resistance exercise. NASA requires countermeasures to keep aerobic capacity and muscle strength at or above 80% of preflight values. [7]
Read more on this site
Bones
What happens in spaceflight
- Weight-bearing bone at the hip and spine loses about 1–1.5% of its mineral density per month in space, faster than older adults lose in a year. [15]
- Recovery is slow: 9 of 17 astronauts had not recovered shin-bone (tibia) mineral density a year after flight. [16]
What crews do about it
- Heavy resistance exercise on the space station's Advanced Resistive Exercise Device (up to 600 pound-force), plus vitamin D and good nutrition. [17][7]
- Bone density scans every three years and after flight. [7][17]
Read more on this site
Kidneys
What happens in spaceflight
- Kidney stone risk rises: bone loss puts more calcium in the urine, and crews make less urine (47% lower early and 39% lower late in long missions in one study). [18]
- In the year after flight, stone incidence may approach 2–7 times the preflight rate. [18]
What crews do about it
- Drinking more water (modeling suggests about 3.2 liters a day), limiting salt, and potassium citrate in selected crew. [18]
Read more on this site
Immune system
What happens in spaceflight
- Changes in the adaptive immune system persist through 6-month space station flights. [19]
- In a study of 23 astronauts on long space station flights, all but one shed at least one dormant herpes virus (Epstein-Barr, varicella-zoster or cytomegalovirus). [20]
What crews do about it
- A pre-launch health stabilization program reduces the chance of catching an infection before launch. [7]
Read more on this site
Whole body: radiation
What happens in spaceflight
- Space radiation mainly raises long-term cancer risk. NASA limits each astronaut's career exposure to below 600 mSv (millisievert). [7]
- A round trip to Mars with current propulsion was estimated at about 0.66 sievert (660 mSv), above that limit. [21]
What crews do about it
- Shielding and shelters against solar storms (shielding works poorly against galactic cosmic rays), radiation monitoring, and limiting mission length. [22]
Read more on this site
How to use it
Select a body system on the figure or in the list. The panel shows what happens in spaceflight, what crews do about it (countermeasures), and links to the detailed clinical, research and learning pages. Every statement is cited to a primary source.
The figure is a simplified drawing, not an anatomical model. Keyboard: Tab to a body system, then Enter or Space to open it.
Limits
- Effects summarize published NASA documents and studies, mostly from long missions on the space station. Short flights cause fewer and milder changes.
- Numbers are averages or study results. Individual crewmembers vary widely.
Evidence profile
- Overall certainty
- ◆◆◆◇ Moderate (proposed)
- Evidence types
- F · Flight dataE · Expert / operational / standards
- Literature through
- 2026-10-14
- Validation
- Statements checked against the cited sources; the explorer is not clinically validated
- Credit
- Educational only; no CME or other credit
Requirements referenced 0
No NASA-STD-3001 requirement maps directly to this page. See the standards quick reference.
References 22
- NASA OCHMO. Spaceflight Associated Neuro-ocular Syndrome (SANS). Medical Technical Brief OCHMO-MTB-001 (2024). www.nasa.gov/wp-content/uploads/2024/02/ochmo-mtb-001-sans.p… NASA E
- NASA OCHMO. Space Adaptation Sickness (SAS). Medical Technical Brief OCHMO-MTB-004 (2025). www.nasa.gov/wp-content/uploads/2025/09/ochmo-mtb-004-space-… NASA E
- NASA OCHMO. Spaceflight Experience and Medical Care. Technical Brief OCHMO-TB-033. www.nasa.gov/wp-content/uploads/2023/12/ochmo-tb-033-spacefl… NASA E
- NASA OCHMO. NASA Spaceflight Medical Selection, Recertification and Mission Evaluation Standards. OCHMO-STD-100.1A, Revision A (2024). ntrs.nasa.gov/citations/20240006194 Standard E
- NASA OCHMO. Behavioral Health and Performance. Technical Brief OCHMO-TB-016. www.nasa.gov/wp-content/uploads/2023/12/ochmo-tb-016-behavio… NASA E
- NASA OCHMO. Pharmaceutical Care. Medical Technical Brief OCHMO-MTB-012, Revision B (2026) (file published as ochmo-tb-006-pharmaceuticals.pdf). www.nasa.gov/wp-content/uploads/2023/12/ochmo-tb-006-pharmac… NASA F
- NASA OCHMO. NASA-STD-3001, Volume 1: Crew Health, Revision C (2023). [V1 3004], [V1 3017], [V1 3018], [V1 4030]–[V1 4033] and Table 4.8-1. www.nasa.gov/wp-content/uploads/2023/11/nasa-std-3001-vol-1-… Standard E
- NASA OCHMO. Orthostatic Intolerance. Technical Brief OCHMO-TB-019. www.nasa.gov/wp-content/uploads/2023/12/ochmo-tb-019-orthost… NASA E
- Lee SMC, Feiveson AH, Stein S, Stenger MB, Platts SH. Orthostatic intolerance after ISS and Space Shuttle missions. Aerosp Med Hum Perform. 2015;86(12 Suppl):A54–A67. doi:10.3357/AMHP.EC08.2015 PMID:26630196 Peer-reviewed F
- Marshall-Goebel K, Laurie SS, Alferova IV, et al. Assessment of jugular venous blood flow stasis and thrombosis during spaceflight. JAMA Netw Open. 2019;2(11):e1915011. doi:10.1001/jamanetworkopen.2019.15011 PMID:31722025 Peer-reviewed F
- NASA OCHMO. Decompression Sickness (DCS) Risk Mitigation. Technical Brief OCHMO-TB-037, Revision D (2026). www.nasa.gov/wp-content/uploads/2023/12/ochmo-tb-037-decompr… NASA E
- Kerstman EL, Scheuring RA, Barnes MG, DeKorse TB, Saile LG. Space adaptation back pain: a retrospective study. Aviat Space Environ Med. 2012;83(1):2–7. doi:10.3357/asem.2876.2012 PMID:22272509 Peer-reviewed F
- Johnston SL, Campbell MR, Scheuring R, Feiveson AH. Risk of herniated nucleus pulposus among U.S. astronauts. Aviat Space Environ Med. 2010;81(6):566–574. doi:10.3357/ASEM.2427.2010 PMID:20540448 Peer-reviewed F
- Moore AD Jr, Downs ME, Lee SMC, Feiveson AH, Knudsen P, Ploutz-Snyder L. Peak exercise oxygen uptake during and following long-duration spaceflight. J Appl Physiol. 2014;117(3):231–238. doi:10.1152/japplphysiol.01251.2013 PMID:24970852 Peer-reviewed F
- NASA Human Research Program. Evidence Report: Risk of Bone Fracture due to Spaceflight-induced Changes to Bone (July 18, 2024). humanresearchroadmap.nasa.gov/evidence/reports/Bone%20Fractu… NASA F
- Gabel L, Liphardt AM, Hulme PA, et al. Incomplete recovery of bone strength and trabecular microarchitecture at the distal tibia 1 year after return from long duration spaceflight. Sci Rep. 2022;12:9446. doi:10.1038/s41598-022-13461-1 PMID:35773442 Peer-reviewed F
- NASA OCHMO. Bone Loss. Medical Technical Brief OCHMO-MTB-013, Revision D (2026). www.nasa.gov/wp-content/uploads/2026/02/ochmo-mtb-013-bone-l… NASA E
- NASA Human Research Program. Evidence Report: Risk of Renal Stone Formation (2024). humanresearchroadmap.nasa.gov/evidence/other/2024%20Renal%20… NASA F
- Crucian B, et al. Alterations in adaptive immunity persist during long-duration spaceflight. NPJ Microgravity. 2015;1:15013. doi:10.1038/npjmgrav.2015.13 PMID:28725716 Peer-reviewed F
- Mehta SK, et al. Latent virus reactivation in astronauts on the International Space Station. NPJ Microgravity. 2017;3:11. doi:10.1038/s41526-017-0015-y PMID:28649633 Peer-reviewed F
- Zeitlin C, Hassler DM, Cucinotta FA, et al. Measurements of energetic particle radiation in transit to Mars on the Mars Science Laboratory. Science. 2013;340(6136):1080–1084. doi:10.1126/science.1235989 PMID:23723233 Peer-reviewed F
- NASA OCHMO. Design for Ionizing Radiation Protection. Technical Brief OCHMO-TB-020. www.nasa.gov/wp-content/uploads/2023/12/ochmo-tb-020-radiati… NASA E
Machine-checked on 2026-10-14: each URL was fetched, each DOI's title and year matched via Crossref, PubMed IDs matched to DOIs, and every number shown was checked against the source text (abstract, NASA document, regulation or official web page). Human verification against full text is still required before review.
Article info
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- Reviewer
- AI-assisted clinical review (AI medical research assistant; no named human clinician)
- Last reviewed
- 2026-10-15
- Literature through
- 2026-10-14
- AI-assisted
- Yes (disclosed)
- COI
- Pending
- License
- CC BY-SA 4.0 (text); code MIT
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- Use
- Educational only · not for clinical decisions · Disclaimer
- Cite this version
- Pending first edition
Educational use only · not medical advice · not for clinical decisions · Disclaimer · CC BY-SA 4.0