  We report on a determination of the Earth-Moon distance performed by students
of an Italian high school, based on measurements of the time delay of the
"echo" in the radio communications between Nasa mission control in Houston and
the Apollo astronauts on the lunar surface. By using an open-source
audio-editing software, the distance can be determined with three digits
accuracy, allowing to detect the effect due to the eccentricity of the orbit of
the Moon.
