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Your Mission

Problem: How can I find my space height?

How tall are you? Are you sure you know the answer? Does your height change in your life, and how much time does it take for your height to change?

So, how tall are you? That seems like a fairly easy question to answer. However, did you know our height changes throughout the day? In fact, our height changes from morning to night. It really has very little to do with the sun and moon, though. Instead, our height becomes less – yes, we shrink – as the day goes on because gravity compresses our bodies. When we lie down at night, gravity no longer pulls in a direction to make us shorter so our bodies stretch and we return to our taller height again. Imagine what happens to astronauts who don’t experience the effect of gravity for months at a time! That’s right; they grow taller. In fact, NASA Astronaut and MissionX ambassador Kate Rubins grew from her "Earth height" of 171 cm to her "space height" of 174.4 cm.

In this NASA video from NASA's Human Research Program, NASA astronaut Mike Barratt and NASA Principal Investigator Sudhakar Rujulu discuss how the body changes in space while explaining the science behind the activity, "What's Your Space Height?"

Ages: 8-12

Topic: Measurement, units

Time: 45 minutes, two classes


Measure lengths indirectly and by iterating length units. Solve problems involving measurement and conversion of measurements.




CCSS.MATH.CONTENT.3.NBT.A.2 fluently add and subtract within 1000 using strategies and algorithms based on place value, properties of operations, and/or the relationship between addition and subtraction.

Lesson Objective

Students will:

  • Measure their body for height, leg length and arm span 
  • Compare measurements for their class


Teachers Note

Suggestions for student engagement: To help engage the students, have them discuss times people have been kind to them, or people with who mthey want to share their kindness. Examples to assist in the duscussions can be astronauts or soldiers being away from their families or people who are not with their families during holidays, etc. Also to be shared are examples highlighting the giving nature of humanity following natural disasters. Students can watch the attached video of a Mission X school team hosting a fundraiser and creating a video for another team from the USA whise city was flooded during Hurricane Harvey in 2017.


Each human is unique, yet there are trends within populations. Credit: NASA

NASA drawings showing range of motion and body measurements. Credit: NASA
The study of body measurements is called anthropometry. At NASA, there is an entire team of people who are anthropometrists. These scientists work and collaborate with a wide variety of design teams because human measurements dictate spacecraft design for seat sizes, hatch openings, spacesuit construction, and much more. NASA has found that the height of astronauts increases approximately 3% over the first 3 to 4 days of weightlessness in space. There are many factors that influence each individual, so each astronaut will experience more or less of an increase than others. As soon as astronauts return back to Earth, gravity pulls on them once again and astronauts will typically return to their pre-flight height in a short amount of time. In space, almost all of this height increase comes from changes in the spinal column, which affects body measurements such as sitting height, eye height, standing height, how space suits fit, and much more. Remember, even though astronauts are floating in space and don't stand and walk around like we do on Earth, their height measurements are important to calculate whether they can perform tasks such as reach buttons and switches or grasp objects. To work on the International Space Station (ISS), the astronauts often brace themselves by placing their feet under bars on the floor to keep from floating away from their work area. The diagram pictured shows this bracing action and the scientists in NASA's Johnson Space Center Human Factors group study many measurements of astronauts to make sure everyone can reach the variety of features on the ISS. It is interesting to note that as astronauts increase height, their shoulder height increases as well. This means that in space, their arms are farther from the floor than on Earth which allows them to reach higher objects when in space. An increasing spinal column length is an important factor to consider when designing spacecraft and habitats. Astronauts must be able to reach everything! Spacecrafts must be built correctly before they fly, because changing the walls or control locations is either not possible or overly expensive once the craft has launched to space.


Expedition 26, with ESA astronaut Paolo Nespoi standing in the center. Credit: NASA
NASA astronaut Kate Rubins returns to Earth 3.4 cm taller than when she left! Credit: NASA
Take a look at the picture of the astronauts in the picture. Astronauts come in all shapes and sizes! For reference, Paolo Nespoli is the Italian astronaut standing in the center of the picture. According to the European Space Agency, Paolo is about 188 cm (74 inches) tall on the Earth. Paolo is taller than most astronauts. Many features in a spacecraft are adjustable for the astronauts using them. Before each flight, the seats of the spacecraft are adjusted to fit each astronaut. And remember, astronauts will be a different height when they return! This means the spacecraft and space suits will fit differently whether one is launching to or returning from space. Do your pajamas fit differently from when you go to bed at night to when you wake up? Let's investigate that concept together!

In this activity, you and your crew members will measure your height and discuss the factors involving how your bodies might change in space. This is just like what astronauts do in space. Astronauts must take scientific measurements, work as a team, and clearly communicate with others. In fact, just like in this activity, astronauts measure their bodies when in space, too!
Safety: This activity has no reasonable associated safety risks.

  Materials: Tape measure

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