Medical conditions in flight
Also: Medical Conditions risk
Distance from EarthRadiationIn-flightLifetime SurveillanceLEO long-durationLunar surfaceMars transit & surfacePublicClinicianResearcher
- Medical events in flight are common, and a few have ended missions early. None has caused a death. ◆◆◆◇ Moderate · F
- For Mars, NASA rates this risk 5×4 and requiring mitigation, because evacuation and resupply won't be possible. ◆◆◆◆ High · E
- Planning relies on models such as the IMM, which estimate risk for 100 conditions but are limited by sparse data. ◆◆◇◇ Low · 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.
NASA risk title (verbatim)
Risk of Adverse Health Outcomes and Decrements in Performance Due to Medical Conditions that occur in Mission, as well as Long Term Health Outcomes Due to Mission Exposures
NASA short title: Medical Conditions · HRP element: Exploration Medical Capability (ExMC) · Status: Active [current research ongoing] [1]
What it is
This risk covers medical conditions that occur during a mission, and long-term health effects of mission exposures, that harm health or performance [1]. Near Earth, sick crew can talk to doctors in real time, get resupplied and be evacuated. Beyond low Earth orbit those advantages fade, so the onboard medical system has to do more [1]. NASA also folded the former acute radiation syndrome risk (from solar particle events) into this one [1].
Current evidence
- Many medical conditions have occurred in flight and after flight. None has caused a crew death. Three in-flight conditions outside the U.S. segment led to an evacuation or an early end of mission [1].
- NASA’s Integrated Medical Model (IMM), a probabilistic risk tool, estimates in-mission risk for 100 medical conditions and has been used officially since 2017 [1]. A published IMM analysis compared medical risk across mission lengths and stressed the model’s limits [4].
- Unexpected conditions can still appear. A study of 11 ISS crew found stagnant or reversed jugular vein flow in 6 and a blood clot (occlusive thrombus) in 1 [5]. A case report describes the in-flight management of that clot [6].
- Few long-term health effects of spaceflight have been characterized so far. Prediction is limited because few people have flown long missions [1].
NASA’s risk posture
NASA scores each risk for each design reference mission (DRM) as likelihood × consequence (LxC). Both run from 1 (lowest) to 5 (highest) on the HSRB’s 5×5 matrix [1][3]. Each score comes with a disposition, such as “Accepted”, “Requires Characterization” or “Requires Mitigation”. These ratings were last approved by NASA’s Human System Risk Board (HSRB) in 5/2021 [1].
| Mission | Duration | In-mission (operations) | Long-term health |
|---|---|---|---|
| LEO | Short (under 30 d) | 3x2 · Accepted | 3x2 · Accepted |
| LEO | Long (30 d–1 yr) | 4x2 · Accepted | 4x2 · Accepted |
| Lunar orbit | Short | 4x2 · Accepted | 3x2 · Accepted |
| Lunar orbit | Long | 5x3 · Requires Mitigation | 4x2 · Requires Characterization |
| Lunar orbit + surface | Short | 4x3 · Requires Characterization | 4x2 · Requires Characterization |
| Lunar orbit + surface | Long | 5x4 · Requires Mitigation | 4x4 · Requires Characterization |
| Mars preparatory | Under 1 yr | 5x4 · Requires Mitigation | 4x4 · Requires Characterization |
| Mars planetary | 730–1,224 d | 5x4 · Requires Mitigation | 5x4 · Requires Characterization |
Copied from the Human Research Roadmap on 2026-10-14. Ratings change. Check the live record before citing.
Open knowledge gaps
NASA lists 7 knowledge gaps for this risk, 7 of them open as of 2026-10-14 [1]. Each gap ID links to its page on the Human Research Roadmap (HRR).
Show NASA’s gap list (verbatim)
| Gap | NASA gap statement | Status |
|---|---|---|
| Medical-101 | We need to characterize the medical conditions that can occur during exploration missions and their relevant associated end states, management options, and the capabilities necessary to manage them (what can happen, how bad could it be, what can we do to improve it?). | Open |
| Medical-201 | We need to characterize the resource “costs” associated with each relevant exploration medical capability. | Open |
| Medical-301 | We need to prioritize the relevant exploration medical capabilities in order to perform medical system trade space analysis. | Open |
| Medical-401 | We need to characterize the predicted resource or risk constraints associated with exploration missions in order to determine which capabilities (and associated resources) should be included in an exploration medical system. | Open |
| Medical-501 | We need to develop integrated exploration medical system models for the Moon and Mars. | Open |
| Medical-601 | We need an quantitative method for assessing whether the value of new exploration medical capability research is of sufficient benefit vs. cost to perform. | Open |
| Medical-701 | We need to increase inflight medical capabilities and identify new capabilities that (a) maximize benefit and/or (b) reduce “costs” on human system/mission/vehicle resources. | Open |
See also Open questions.
Active countermeasure research
- Exploration Medical Capability (ExMC). NASA is defining the medical needs for lunar and Mars missions and designing a medical system that is integrated with the vehicle. The trade-offs between medical capability and mass, volume, power and data are explicit [1].
- Planning the medical system. Gap work covers which conditions to plan for, what each capability costs in resources, how to prioritize capabilities, and integrated medical-system models for the Moon and Mars (gaps Medical-101 to Medical-601) [1].
- Technologies. Gap Medical-701 covers diagnosis, treatment and crew training technologies; HRR lists linked tasks on ultrasound, in-flight blood analysis and assisted medical procedures [1].
Project-level detail, including status, investigators and results, is in the NASA Task Book and on each HRR gap page.
Clinical articles
For practical, clinic-facing guidance, see:
- In-flight Medical Emergencies, Capabilities & Evacuation: LEO vs Moon vs Mars
- Space Pharmacology: Medical Kits, Medication Use and Drug Stability
- Point-of-Care Ultrasound in Spaceflight: Diagnostics When Ultrasound Is the Only Imaging
- Clinician Quick-Start: Seeing a Patient Who Flew — or Will Fly — to Space
Evidence profile
- Overall certainty
- ◆◆◇◇ Low (proposed)
- Evidence types
- F · Flight dataC · ComputationalE · Expert / operational / standards
- Literature through
- 2026-10-14
- NASA source
- Human Research Roadmap risk page (last published 05/13/25; read 2026-10-14)
Requirements referenced 6
| Requirement | Title | Plain-language meaning |
|---|---|---|
| [V1 3004] | In-Mission Medical Care | Training, capabilities and resources to diagnose and treat conditions, based on probabilistic risk assessment and mission constraints. |
| [V1 3006] | Crew Medical Officers | At least two crewmembers per vehicle trained as medical officers (moved to Section 5.2 in Rev C). |
| [V1 3007] | Medical Evacuation | Evacuation to a higher level of care must be available for conditions beyond onboard capability; preservation of life supersedes the mission. |
| [V1 3009] | Palliative Comfort Care | Required when resources are exhausted, return is not feasible and survival is impossible. |
| [V2 7043] | Medical Capability | Vehicle medical system meeting Volume 1 requirements. |
| [V2 7045] | Medical Equipment Usability | Usable by non-physicians, including if the physician is the patient. |
IDs as published in NASA-STD-3001 Vol. 1 Rev C (2023-09-15) and NASA-STD-3001 Vol. 2 Rev F (2026-07-14). NASA-STD-3001 binds NASA programs; it is not a regulation for commercial flights. Paraphrased. Standards quick reference.
References 6
- NASA Human Research Roadmap. Risk record: “Risk of Adverse Health Outcomes and Decrements in Performance Due to Medical Conditions that occur in Mission, as well as Long Term Health Outcomes Due to Mission Exposures”. Accessed 2026-10-14. humanresearchroadmap.nasa.gov/Risks/?i=95 NASA E
- NASA Human Research Program. Evidence report for the Medical Conditions risk (approved May 8, 2017). humanresearchroadmap.nasa.gov/evidence/reports/Medical.pdf NASA E
- Antonsen EL, et al. Updates to the NASA human system risk management process for space exploration. NPJ Microgravity. 2023;9:72. doi:10.1038/s41526-023-00305-z PMID:37679359 Peer-reviewed E
- Antonsen EL, et al. Estimating medical risk in human spaceflight. NPJ Microgravity. 2022;8:8. doi:10.1038/s41526-022-00193-9 PMID:35361776 Peer-reviewed C
- Marshall-Goebel K, 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
- Auñón-Chancellor SM, et al. Venous thrombosis during spaceflight. N Engl J Med. 2020;382(1):89–90. doi:10.1056/NEJMc1905875 PMID:31893522 Peer-reviewed F
Machine-checked on 2026-10-14: each URL resolved, each DOI's title/journal/year matched via Crossref, and claims were checked against the source text (abstract or full NASA page). Human verification against full text is still required before review. NASA documents are U.S. Government works (public domain) and are summarized with attribution; journal articles are summarized, not reproduced.
Article info
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- Last reviewed
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- Literature through
- 2026-10-14
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