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 open-source audio-editing software, the distance can be determined with a0.1% accuracy, allowing us to observe the effect of the eccentricity of the orbit of the Moon.

1.
E. M.
Rogers
,
Physics for the Inquiring Mind: The Methods, Nature, and Phylosophy of Physical Science
(
Princeton U. P., Princeton, NJ
,
1960
), Chap. 14.
2.
E.
Roger Cowley
, “
A classroom exercise to determine the Earth-Moon distance
,”
Am. J. Phys.
57
(
4
),
351
352
(
1989
).
3.
David H.
Bruning
, “
Determining the Earth-Moon distance
,”
Am. J. Phys.
59
(
9
),
850
(
1991
).
4.
J.
Faller
 et al., “
Laser Beam Directed at the Lunar Retro-Reflector Array: Observations of the First Returns
,”
Science
166
(
3901
),
99
102
(
1969
).
6.
D.
Keeports
, “
Estimating the Speed of Light from Earth-Moon Communication
,”
Phys. Teach.
44
(
7
),
414
415
(
2006
).
7.
F.
Glick
, “
Velocity of Light from the Earth-Moon-Earth Communications Delay
,”
Am. J. Phys.
40
(
12
),
1867
1868
(
1972
).
10.
J. D.
Giorgini
 et al., “
JPL’s On-Line Solar System Data Service
,”
Bull. Am. Astron. Soc.
28
,
1158
(
1996
); http://ssd.jpl.nasa.gov/?horizons.
11.
Stellarium 0.8.2, http://www.stellarium.org/.
12.
K. E.
Peltzer
,
Apollo Unified S-Band System
(Goddard Space Flight Center,
1966
), available at http://history.nasa.gov/alsj/TM-X55492.pdf.
13.
Apollo 17 Mission Report, available at http://history.nasa.gov/alsj/a17/A17/Mission_Report.pdf.
14.
The same observation was made in Ref. 6 and used to estimate the speed of light, see also Ref. 7.
AAPT members receive access to the American Journal of Physics and The Physics Teacher as a member benefit. To learn more about this member benefit and becoming an AAPT member, visit the Joining AAPT page.