• Question: How heavy is the ISS and does gravity affect it. Also, how does it stay up there

    Asked by Harvinator to Elie, Floris, Jenn, RocketRich on 16 Mar 2016.
    • Photo: Richard Moss

      Richard Moss answered on 16 Mar 2016:

      The ISS is about 400 tons. We constructed it over 15 years, piece by piece.
      Actually it is close enough to the Earth that gravity affects it almost the same as for you and me. BUT it is spinning around the Earth and in effect “falling” but never hitting the surface. So the effect is like no gravity, which we actually call “microgravity”. It is like being in a falling lift that never hits the floor!
      There is a little bit of atmosphere which causes friction as the ISS moves. Like with a car, when you stop pushing the accelerator the car will slow down as the wind makes friction. So the ISS needs to burn fuel to “boost” up the orbit every month. That is how it stays there.