Lunar and Planetary Institute

Space Stations - Measure Up!
EXPLORE! Health in Space

Space Stations - Measure Up!


In Measure Up!, children ages 8–13 work in pairs to measure each other's ankles with lengths of string before and after lying on their backs with their feet in the air for 1 minute. This simulates the microgravity of space, where everything — including body fluids — floats!

What's the Point?

  • In microgravity objects "float." So do fluids, including the fluids inside the human body. This fluid shift causes the upper portion of astronauts'' bodies to swell, and their lower extremities to shrink.


The following materials are for one Measure Up! activity set
Three sets are recommended for a station

    • 1 ruler
    • 2 different colors of permanent markers
    • 1 18-inch length of string that will not stretch
    • A writing utensil and scrap paper
    • Timer or watch
    • Children's Guide for Measure Up!

For the facilitator:

Lying downPreparation

  • Cut an 18" length of string for each pair of children.
  • Place the materials at the station with a copy of the Children's Guide for Measure Up!


Described in the Children's Guide


After measuring their ankles before and after the simulated microgravity conditions of space, the children should have observed a marked change. Within just one minute, their ankle circumference may have decreased by a half inch or more!

Even though they were not really in microgravity conditions and the fluids in their bodies did not float, the children can see that fluids can shift! They may have also guessed that some of the effects resulting from the rising of fluids to the upper body are headaches, stuffy noses, and puffy faces.

A Little Background for the Facilitator

Pictures of astronauts on the International Space Station show that their faces are fuller there than on Earth. Why is this? Well, once again, it's all about the pull of gravity or lack of it!

Our bodies are made of 60% water, most of which is contained in our cells and circulatory system. Our bodies are well adapted to dealing with Earth's gravity; our hearts pump our blood and keep it from pooling in our feet. In microgravity conditions, however, things float. This includes the fluids in the human body! Within minutes of experiencing microgravity, fluids in the astronauts' bodies shift, causing puffy faces and shrunken legs and extremities — what they call "chicken leg syndrome!"

This fluid shift does affect the astronauts; they may suffer from headaches and stuffy noses in addition to puffy faces. The symptoms go away within a few days after they return to Earth.

Last updated
February 9, 2010

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