Lunar and Planetary Institute

Space Stations - Sponge Spool Spine
EXPLORE! Health in Space

Space Stations - Sponge Spool Spine


Children ages 8–13 simulate what happens to a human spine in space by making Sponge Spool Spine(alternating sponge pieces and spools threaded on a pipe cleaner). This represents a human spine on Earth, with the discs (sponges) pressed between the spinal vertebrae (the wooden spools). The children measure the spine length, dip it in a glass of water (simulating microgravity), and then re-measure the spine. They will find it has expanded, just like in space!

What's the Point?

  • Earth's gravity pulls us toward Earth's center; its pull compresses our spines.
  • In microgravity, where there is no net force pulling us "down," our spines elongate.

Sponge Bob


The following materials are for one Sponge Spool Spine activity set
Three sets are recommended for a station:

  • A tall, clear (not translucent) container filled ¾ full with water (a clear 2-liter soda bottle with the top few inches cut off works well)
  • A ruler
  • 1 pencil (slightly sharpened)
  • Scratch paper and writing utensils
  • Children's Guide for Sponge Spool Spine

For each child:

  • 2 pipe cleaners
  • 3–4 small wooden spools (may be purchased at craft stores
  • 3-4 sponge cut-outs, about the size of a dime

Regular sponges will work. For truly astounding results use super compressed sponges (may be purchased at specialty household goods stores such as William Sonoma).

  • 1 circular sponge cut-out about the size of a half-dollar for a Sponge Spool Spine head (optional)

For the facilitator:


  • Cut the sponges into small squares first. You can round off the edges to form circles if you wish. Make sure the sponges are completely dry before placing them at the station.
  • Using a slightly sharpened pencil, poke holes in the center of the sponge discs.
  • If you are working with older children, you can have them prepare the sponges. Plan for extra time. Prepare the sponges ahead if the activity is being done with young children.
  • Place the materials and a copy of the Children's Guide for Sponge Spool Spine at the station.


Described in the Children's Guide


The force of Earth's gravity pulls on our skeletons, causing our spines to compress. This model represents what happens to our spines in reduced gravity — they elongate because there is no net gravitational force pulling on them. So space travelers get taller! But they also get backaches and stretched nerves!

A Little Background for the Facilitator

Our bones form the support structure of our bodies. And a primary component is our spine — the 33 vertebrae that extend from our skulls to our pelvis. The bones are separated by thin pads of tough fiber (inter-vertebral discs). This inter-layering of bone and disk allows our spines to be flexible — letting us bend and twist, but still protecting the important nerves in our spinal cord.

Our bodies are adapted to Earth's gravity — that force that pulls us and every other object on Earth toward the center of Earth. This gravitational force compresses our spines; we do not sense the compression because we are used to it. But in microgravity settings like on the Space Station, this compressive force is no longer present — and our spines stretch! Astronauts actually grow 2 to 3 inches taller (5 to 8 centimeters) when they are in space!

While this might seem neat to become taller, it can actually cause them some pain; many astronauts have back pain while they are in space and the stretching can potentially injure nerves.

The height increase is not permanent. Once astronauts return to Earth, their spine compresses again in just a few days.

Last updated
February 9, 2010

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