In 2014, NASA astronauts used an ordinary tape measure during six-month ISS missions; the Body Measures data later entered requirements for NASA's xEMU spacesuit

As opposed to putting a tape measure back in a drawer when it is not needed, NASA used one as part of the Body Measures experiment aboard the International Space Station in 2014. The study involved astronauts taking body measurements at different points during their missions to understand how the human body changes during extended exposure to microgravity. NASA's Integrated Extravehicular Activity Human Research & Testing Plan: 2019 lists a tape measure among the equipment used for the study, alongside an anthropometer and weight scale, with digital still photography, video imaging, and 3-D whole-body scanning also used to collect information about body shape, size, and posture. The same plan says that preflight, inflight and postflight anthropometry data from the completed Body Measures study were incorporated into the requirements for the Exploration Extravehicular Mobility Unit, or xEMU.

The experiment was not simply about finding out whether an astronaut's spine became longer in space. NASA was interested in changes in body dimensions, neutral posture, and spinal elongation during long-duration exposure to microgravity, because these factors can affect the way an astronaut fits inside a spacesuit. The 2019 plan describes the study as measuring changes in anthropometry that were important to suit-sizing parameters. That made the project less about one particular measurement and more about understanding how the human body changes as a mission progresses.

What astronauts were measuring in space


The Body Measures work appears repeatedly in NASA's 2014 International Space Station reports. During one session documented in August, Commander Steven Swanson and Flight Engineer Reid Wiseman carried out Body Measures sessions on different flight days. They set up body-marker instrumentation, took calibration and body-pose photographs, recorded circumference measurements and captured a video of neutral body posture. NASA's records show that the experiment was a recurring activity rather than a single measurement taken once during the mission.

NASA's November records show another example of the work. ESA astronaut Alexander Gerst measured his body shape and size aboard the station on Nov. 5, with NASA astronaut Reid Wiseman assisting him with the Body Measures study. Gerst was part of the Expedition 41 crew that returned to Earth on Nov. 9 after 165 days in orbit. These reports help put the experiment into context: the measurements were being collected from astronauts who were spending months in space, not from people making a quick demonstration for a laboratory experiment.

The equipment list in NASA's later technical plan should also be read as describing the broader study rather than as a claim that every instrument was simultaneously being carried around the station. The report identifies an anthropometer, tape measure, and weight scale for anthropometric measurements and separately describes digital photographs, video imaging, and a 3-D whole-body scanner. NASA says these methods were used to measure changes in body shape, size, and posture during spaceflight. This distinction matters because a 3-D scanner and a tape measure served very different purposes, while the Body Measures dataset brought their information together.

The timing of the changes was another important finding. NASA's analysis found that most anthropometric changes occurred within the first 15 to 20 days of a mission, with some circumference measurements following a different pattern. After this initial period of larger changes, the researchers observed smaller fluctuations through the remainder of the mission. For spacesuit designers, that meant body dimensions could not simply be treated as a fixed set of numbers measured before launch. NASA's report says future suits may need to be adjustable according to mission duration, and that predicting changes in anthropometry could help determine whether additional sizing adjustments would be necessary.

How the measurements made their way into spacesuit design

The Body Measures results did not remain as a record of what happened to astronauts on the ISS. NASA was also developing human-space-suit interaction models and testing methods that could help researchers examine how changes in body dimensions might affect suited comfort and performance. The 2019 plan says these models and human-in-the-loop testing could help determine the extent to which changes in anthropometry during flight affect how an astronaut functions inside a suit.

That is where the tape measure becomes part of a much larger engineering process. A single waist or limb measurement does not explain how an entire body will interact with a pressurized suit. When combined with posture information, photographs, scans and measurements collected at different stages of a mission, however, individual dimensions become part of a broader picture of how the astronaut's body behaves in space. NASA's work also included efforts to develop customized three-dimensional body models from key anthropometric measurements, giving engineers another way to examine different body shapes during suit development.

The 2019 NASA plan makes the link to xEMU particularly clear. It states that the preflight, in-flight, and postflight anthropometry data from the completed Body Measures study were incorporated into the xEMU requirements document, SSP 51073. At the time, xEMU was NASA's next-generation spacesuit effort intended to support future extravehicular activities, including lunar exploration. So the measurements collected during the ISS study became part of the technical foundation for a more advanced spacesuit design.

The story needs one important update when viewed from 2026. xEMU did not remain the single flight program described in the 2019 planning document. NASA later changed its acquisition strategy and moved toward the Exploration Extravehicular Activity Services, or xEVAS, model. In 2022, the agency selected Axiom Space and Collins Aerospace to develop next-generation spacesuits under the commercial approach. NASA has since described the xEMU design as a government reference design whose technology, data, and development experience could be used by commercial providers.

Axiom's lunar suit, known as the Axiom Extravehicular Mobility Unit, or AxEMU, is therefore better described as building on NASA's earlier xEMU work rather than simply being the same xEMU suit waiting to fly. NASA says the AxEMU draws on the agency's previous spacesuit prototype development, including the experience, technology, and data developed through xEMU. The agency selected Axiom to provide the moonwalking system for Artemis III, while the broader commercial approach is being used for future spacesuit services.

The contrast is what makes the Body Measures experiment so interesting. Spacesuit development involves sophisticated scanning, computer modeling, testing, and engineering, but some of the basic information begins with measurements of the people who will eventually wear the equipment. In 2014, astronauts aboard the ISS repeatedly recorded body dimensions and posture as their missions progressed. NASA then used the resulting anthropometric information in the xEMU requirements process, and that earlier work became part of the technical foundation available to the next generation of commercial suit developers.

A tape measure was never the whole story. It was one tool within a much broader study designed to understand the changing human body in space. That distinction makes the result more interesting, not less. The experiment shows how ordinary measurements, collected carefully over time and combined with more advanced imaging and modeling, can become useful engineering data. What began with astronauts measuring themselves in orbit ultimately contributed to NASA's understanding of what a future exploration spacesuit would need to accommodate.