• Question: Does the spine decompress in zero gravity, do the astronauts come back taller, and by how much?

    Asked by Steven on 2 Jan 2016. This question was also asked by Joysephine.
    • Photo: Floris Van Den Berg

      Floris Van Den Berg answered on 2 Jan 2016:

      Hi Steven,

      with longer missions the spine of astronauts can stretch up to 3%. Which means up to 6cm! On earth this effect is undone.


    • Photo: Steve Price

      Steve Price answered on 2 Jan 2016:

      Our bodies support us in a 1g environment. Gravity pulls us down from our head to our feet. Our bones and muscles resist that force which allows us to keep upright. When people are in zero g they don’t need this support.
      On return to Earth the bones and muscles need to support our bodies again.

    • Photo: Jean-François Clervoy

      Jean-François Clervoy answered on 18 Jan 2016:

      Hi Steven,

      Yes all astronauts have a significant increase of their spine length, caused simply by the decompression of the intervertebral disks. It can range from few millimetres up to several centimetres, depending on the individual and on the flight duration. It must be taken into account when adjusting size-dependent crew equipment before flight, such as the EVA spacesuits, or the seat liners for the Soyuz spacecraft used for their return.