Apollo 15 Hammer-Feather Drop Apollo 15 Hammer-Feather Drop

The Apollo 15 Hammer-Feather Drop

4 Mb MP4 movie of the demonstration

At the end of the last Apollo 15 moon walk, Commander David Scott (pictured above) performed a live demonstration for the television cameras. He held out a geologic hammer and a feather and dropped them at the same time. Because they were essentially in a vacuum, there was no air resistance and the feather fell at the same rate as the hammer, as Galileo had concluded hundreds of years before - all objects released together fall at the same rate regardless of mass. Mission Controller Joe Allen described the demonstration in the "Apollo 15 Preliminary Science Report":

During the final minutes of the third extravehicular activity, a short demonstration experiment was conducted. A heavy object (a 1.32-kg aluminum geological hammer) and a light object (a 0.03-kg* falcon feather) were released simultaneously from approximately the same height (approximately 1.6 m) and were allowed to fall to the surface. Within the accuracy of the simultaneous release, the objects were observed to undergo the same acceleration and strike the lunar surface simultaneously, which was a result predicted by well-established theory, but a result nonetheless reassuring considering both the number of viewers that witnessed the experiment and the fact that the homeward journey was based critically on the validity of the particular theory being tested.
Joe Allen, NASA SP-289, Apollo 15 Preliminary Science Report, Summary of Scientific Results, p. 2-11

(* the 0.03-kg value is too high, typical feathers have masses between 0.0003 and 0.003 kg (0.3 - 3 grams), this may be due to a typo in the report.)

Apollo 15 Hammer-Feather Drop Apollo 15 Hammer-Feather Drop
The Hammer-Feather Drop - 4 Mb MP4 movie

Larger Version - 20 Mb MP4 movie

Apollo 15 Home Page

Dr. David R. Williams, dave.williams@nasa.gov
NSSDCA, Mail Code 690.1
NASA Goddard Space Flight Center
Greenbelt, MD 20771

NASA Official: Dave Williams, david.r.williams@nasa.gov
Last Updated: 31 March 2023, DRW