Spaceflight-associated Motion Sickness in Commercial Crew Astronauts

Torin K. Clark; Aaron A. Allred; Jaime Mateus; Marissa Rosenberg

AI summary · arXiv: 2610.24216v1 · q-bio.NC

Spaceflight-associated Motion Sickness in Commercial Crew Astronauts

Torin K. Clark, Aaron A. Allred, Jaime Mateus, Marissa Rosenberg

Original paper Submitted to arXiv on 16 Oct. 2026 4 figures, 1 table License: CC BY 4.0

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The essentials

In eight commercial astronauts, space motion sickness was common and often severe, while postflight motion sickness was less frequent and less severe after short-duration missions.

Question

How often do commercial crew astronauts experience space motion sickness (SMS) and terrestrial readaptation motion sickness (TRMS), and how do their severity and persistence change over time? The study addresses gaps in real-time reporting and data from balanced female and male commercial crews.

Method

The authors assessed eight crew members (4 female, 4 male; ages 28–62) from Polaris Dawn and Fram2, with orbital durations of 4.9 and 3.6 days. Crew reported motion sickness on a 0–20 scale after a standardized head-tilt sequence at planned times in flight and after splashdown; the authors calculated incidence, maximum severity, and persistence and compared in-flight with postflight reports.

Findings

Result Seven of eight crew members reported SMS, an incidence of 87.5%.
See the passage in the paper
Inflight 7 of 8 crewmember reported at least some motion sickness (incidence = 87.5%, 95% confidence interval (CI) for proportion = 47.35 to 99.68%)
Result Five of eight crew members reported vomiting in flight, while none reported vomiting after these short-duration flights.
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Inflight, 5 of 8 crewmembers (1 on Polaris Dawn and all 4 crewmembers on Fram2) reported vomiting (62.5% incidence, CI: 24.5 to 91.5%), while no crew reported vomiting postflight after these short-duration flights (0%, CI: 0 to 36.94%).
Result Postflight motion sickness severity was significantly lower than in-flight severity.
See the passage in the paper
Following these short duration flights, postflight motion sickness severity was significantly lower than that inflight (paired t-test, t(7) = 3.76, p=0.007, averaging 14.9 vs. 4.8 of 20, with mean SMS vs. TRMS difference of 10.1, 95% CI = 3.8 to 16.5).
Result On average, in-flight symptoms persisted longer than postflight symptoms, although the difference was not statistically significant.
See the passage in the paper
Postflight motion sickness persisted for an average of 0.78 days (18.7 hours, 95% CI: 0.065 to 1.50 days), which was slightly (but insignificantly) shorter than inflight (paired t-test, t(7)=1.89, p=0.1003, 95% CI: -0.27 to 2.41 days).
Authors’ interpretation The authors argue that the study provides a systematic baseline for motion sickness in commercial crews and can inform operational planning as human spaceflight expands.

Limitations

The small sample of eight crew members limits the strength and generalizability of comparisons, including analyses by sex.
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While our sample is small and should be built upon in future investigations, we found a 100% incidence of SMS among these four female commercial flyers, and a 50% incidence of TRMS.
Crew activities and motions were not controlled, and could have affected reported symptoms and adaptation.
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Crewmembers performed numerous operational and scientific activities in parallel to this study that may have influenced their motion sickness reports that could not be controlled for.
Medication use was not randomized or placebo-controlled, so the study could not assess medication efficacy.
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Anti-motion sickness medications may contribute to delayed onset or relapse in symptoms, though given our small sample size and non-randomized nor placebo-controlled drug administration we cannot assess the efficacy.

Why it matters

The authors present real-time, standardized assessments of both SMS and TRMS in a balanced commercial crew cohort, addressing gaps in retrospective reporting and limited data on women. They argue that these baseline findings can help inform mission operations and the development of countermeasures as commercial missions expand.

Written by AI from the paper. Passages are checked word for word against the text we analysed; the rest may contain errors.

AI-generated keywords: space motion sickness terrestrial readaptation motion sickness commercial astronauts microgravity symptom duration

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Comprehensive Summary
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Original abstract

The paper examines the incidence, severity, and duration of spaceflight-associated motion sickness after entering microgravity and returning to Earth. It distinguishes space motion sickness (SMS), which occurs in orbit, from terrestrial readaptation motion sickness (TRMS), which follows the return to gravity. The authors note that previous evidence relied heavily on retrospective reports from predominantly male government-agency astronauts. Few studies tracked symptoms systematically over time or standardized the head movements that can trigger them. To address these gaps, the researchers followed eight commercial crew members from the Polaris Dawn and Fram2 missions: four women and four men, aged 28 to 62. Both missions used SpaceX Crew Dragon spacecraft and were short, lasting 4.9 and 3.6 days in orbit. Crew members rated their motion sickness on a scale from 0 to 20, with zero indicating no symptoms and 20 indicating vomiting or feeling about to vomit. Reports were scheduled about 30 minutes and six hours after reaching orbit, then daily, with similar reports after splashdown. Before reporting, participants were asked to perform a sequence of head tilts unless they felt too sick. Researchers also recorded self-reported use of anti-motion-sickness medication and collected some additional verbal reports. The researchers calculated the incidence and maximum severity of symptoms for each participant. They defined symptom persistence as the time until ratings first fell below three and remained below that level. For participants whose symptoms had not fallen below the threshold by their final report, the final report time was treated as a lower-bound estimate of symptom duration. Seven of the eight crew members reported some SMS, an incidence of 87.5% (95% confidence interval: 47.35–99.68%). Five reported vomiting in orbit (62.5%). Severity varied considerably, and five crew members reached the maximum score of 20. Four showed the commonly described pattern of symptoms beginning within minutes or hours and then improving. Others experienced delayed onset or a later relapse. SMS lasted an average of 1.85 days, or about 44.4 hours. Symptoms persisted for at least three days in two crew members, although the short missions and limited reporting made it difficult to assess longer-lasting symptoms. Four of the eight crew members reported TRMS, an incidence of 50% (95% confidence interval: 15.7–84.3%). No one reported vomiting after landing. All four Polaris Dawn crew members reported no TRMS, while all four Fram2 crew members reported symptoms. The authors suggest that greater capsule motion after Fram2’s splashdown may have contributed, but the study cannot establish a cause. Peak TRMS severity was significantly lower than peak SMS severity, with mean scores of 4.8 and 14.9 out of 20, respectively (p = 0.007). TRMS lasted an average of 0.78 days, or about 18.7 hours. Although this was shorter than the average duration of SMS, the difference was not statistically significant. Medication use was common, but it was not randomized or controlled, so the study cannot determine whether medication affected symptom severity or timing. Overall, the findings provide an initial systematic account of motion sickness in a commercial crew cohort with equal numbers of women and men. They show that symptoms can be severe and persist for days, particularly in orbit. However, the sample of eight participants is too small to support reliable comparisons by sex, mission, age, or prior motion-sickness history. Differences between missions may also reflect factors other than capsule motion. Crew activity, head movements outside the prescribed sequence, medication use, and reporting frequency were not controlled. The authors therefore present the results as a baseline rather than a definitive estimate for commercial astronauts generally and call for larger studies with more consistent reporting and controlled assessments of medication use and mission conditions.

Spaceflight-Associated Motion Sickness in Commercial Crew Astronauts

Motion sickness in space is often described as an early challenge of adapting to weightlessness. But what happens after astronauts return to Earth—and how long can symptoms last? In “Spaceflight-associated Motion Sickness in Commercial Crew Astronauts,” Torin K. Clark, Aaron A. Allred, Jaime Mateus, and Marissa Rosenberg examine symptoms both in orbit and after landing.

The study offers a rare, systematic look at commercial crew members rather than relying mainly on astronauts’ memories after a mission. Its small sample cannot settle every question, but it helps show how varied spaceflight-related motion sickness can be.

Two kinds of motion sickness

The researchers distinguish between space motion sickness (SMS), which occurs in microgravity, and terrestrial readaptation motion sickness (TRMS), which can arise when crew members return to Earth’s gravity. Both may affect comfort and daily activity, but they occur in different environments and may follow different patterns.

Earlier evidence had important limitations. It often came from retrospective reports by predominantly male government-agency astronauts. Few studies tracked symptoms regularly over time or used a standardized set of head movements that could provoke motion sickness. The new study aimed to address some of these gaps.

How the study tracked symptoms

The researchers followed eight commercial crew members from the Polaris Dawn and Fram2 missions: four women and four men, aged 28 to 62. Both missions used SpaceX Crew Dragon spacecraft and were short, lasting 4.9 and 3.6 days in orbit.

Crew members rated their motion sickness from 0 to 20. A score of zero meant no symptoms; 20 meant vomiting or feeling as though vomiting was imminent. Reports were scheduled around 30 minutes and six hours after reaching orbit, then daily. Similar reports were collected after splashdown.

Before reporting, participants were asked to complete a sequence of head tilts unless they felt too sick. The researchers also noted self-reported use of anti-motion-sickness medication and collected some additional verbal reports. Symptom duration was measured as the time until ratings first fell below three and stayed below that level. If symptoms had not reached that threshold by a participant’s final report, the duration was treated as a minimum estimate.

Symptoms in orbit were common and sometimes severe

Seven of the eight crew members reported at least some SMS, an incidence of 87.5%. Five reported vomiting in orbit, and five reached the maximum symptom score of 20. The results suggest that orbital motion sickness can be intense, even on short commercial missions.

Symptoms did not follow one pattern for everyone. Four crew members experienced the commonly described course: symptoms began within minutes or hours of reaching orbit and then improved. Others had a delayed onset or a later return of symptoms. On average, SMS lasted 1.85 days, or about 44.4 hours. For two participants, symptoms persisted for at least three days, though the short missions and limited reporting make it difficult to know how much longer they might have continued.

Symptoms after landing were milder on average

Four of the eight participants reported TRMS, and none reported vomiting after landing. The pattern differed sharply between the two missions: all four Polaris Dawn crew members reported no TRMS, while all four Fram2 crew members did report symptoms.

The authors suggest that greater capsule motion after Fram2’s splashdown could have contributed, but the study cannot establish that as the cause. Other differences between the missions or their crews may also have played a role.

Peak TRMS severity was significantly lower than peak SMS severity: mean scores were 4.8 and 14.9 out of 20, respectively. TRMS lasted an average of 0.78 days, or about 18.7 hours. Although that was shorter than the average duration of SMS, the difference in duration was not statistically significant.

What the findings can—and cannot—tell us

The study provides an initial, structured account of motion sickness in a commercial crew group with equal numbers of women and men. It highlights that symptoms can be severe and may last for days, particularly in orbit. It also shows why measuring symptoms repeatedly can reveal delayed onset or relapse that a single report might miss.

At the same time, eight participants are too few to support reliable comparisons by sex, age, mission, or prior motion-sickness history. Medication use was common but not randomized or controlled, so the study cannot determine whether medication changed symptom severity or timing. Crew activity, head movements beyond the prescribed sequence, and reporting frequency were also not controlled.

The results are best understood as a baseline, not a definitive estimate for commercial astronauts generally. Larger studies with consistent symptom tracking and controlled assessments of medication use and mission conditions will be needed to clarify who is most at risk, how symptoms unfold, and what may help crew members adapt.

Created on 30 Oct. 2026

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Spaceflight-associated Motion Sickness in Commercial Crew Astronauts

The essentials

Question

Method

Findings

Limitations

Why it matters

Read further

Definitions

Spaceflight-Associated Motion Sickness in Commercial Crew Astronauts

Two kinds of motion sickness

How the study tracked symptoms

Symptoms in orbit were common and sometimes severe

Symptoms after landing were milder on average

What the findings can—and cannot—tell us

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