NASA began implementing an expanded astronaut body measurements requirement aboard the International Space Station in July 2026. The protocol records stature, torso length, and body circumferences before, during, and after a mission. It is designed to support clinical care, track how bodies change in space, and identify changes affecting spacesuit and seat fit.
A presentation by Karen Young and colleagues from Leidos, Aegis Aerospace, and NASA’s Johnson Space Center describes the measurement procedures and early implementation. The work extends anthropometry, the measurement of human body size and shape, beyond its established role in hardware sizing to repeated health surveillance across a mission.
Microgravity changes body dimensions through spinal elongation, fluid redistribution, and losses of muscle and bone. These responses differ between individuals. A suit or seat fitted before launch can consequently fit differently before the journey home. NASA’s earlier research, also discussed in New Space Economy’s coverage of the human body in space, connects these physical changes to spacecraft design and spacesuit fit.
The presentation reviews earlier measurements from Skylab, the Apollo-Soyuz Test Project, the Space Shuttle, and the station. Historical findings included stature increases of about 3% and seated-height increases of about 6%. Those figures describe previous studies, rather than results from the protocol introduced in July. The new measurements are intended to establish how quickly changes occur, how much individuals differ, and how their dimensions recover after landing.
Selecting Measurements That Crews Can Repeat
The team used a ground pilot study involving six subjects to select measurements and procedures. Each subject attended two sessions approximately one week apart, with measurements repeated three times. Operators with anthropometry training were compared with operators who had received none. The study also compared a tape measure with an anthropometer, a device used to measure body dimensions.
Untrained operators tended to overestimate dimensions. Locating anatomical reference points directly on skin produced more reliable measurements than locating them on clothing. Stature measurements did not differ significantly between the tape and anthropometer, but tape measurements tended to overestimate torso length in both operator groups.
The circumference results also varied by body region. Differences between operator groups were small for chest and upper-thigh measurements. Waist and calf measurements were less consistent among untrained operators. Untrained operators improved after their first session, supporting the inclusion of preflight instruction.
The selected measurement set includes stature, torso length, calf height, and circumferences of the head, chest, waist, thigh, mid-thigh, and calf. Each measurement serves an identified purpose, such as assessing body-shape change, checking garment fit, or informing suit and seat sizing. The Aerospace Medical Board concurred with implementing the selected set on the station as soon as feasible.
A Schedule Spanning Launch and Return
The station protocol uses a tape measure and procedures incorporated into an EveryWear iPad questionnaire. Its schedule calls for measurements 30 days before launch; seven, 90, and 180 days after launch; 14 days before return; and between one and five days after landing.
The early inflight and postflight measurements address questions that widely spaced observations cannot resolve. They allow comparisons near the beginning of adaptation to microgravity and shortly after the return to gravity. Measurements before departure from the station also document the body dimensions relevant to return equipment.
At the stage described in the presentation, three subjects had provided partial inflight data without preflight measurements. The authors could not establish whether those data were acceptable without the missing baseline. Another three subjects had completed training and baseline measurements and were expected to supply the first complete datasets.
The planned analysis will compare changes in circumference with body mass and examine changes in stature and torso length. Researchers want to determine whether body dimensions can provide useful information about nutrition and health when future vehicles lack dedicated body-mass measurement equipment. The presentation reports this as an analytical objective, not an established replacement for measuring mass.
For future Artemis surface operations, the team proposes measurements soon after lunar landing and again before ascent. On the station, the immediate next step is to collect complete paired records across flight phases, allowing individual changes to be related to health observations and any required adjustments to suits, seats, or other fitted hardware.
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