Why Hammer and Feather?

At the end of the third and final moonwalk of Apollo 15 David Scott, Commander, carried out a beautiful , simple experiment. Speaking to the tv camera on the lunar rover he held up his geological hammer and a feather. He explained that Galileo had realised that all objects are equally affected by gravity, so, without air, both the hammer and feather should land at the same time. The feather came from a falcon, for which their LM was named.hammerfeather_06.jpg

Scott dropped the hammer and feather (video) and they did, indeed, reach the ground at the same time. Scott exclaimed “How about that. That proves that Mr Galileo was correct in his findings” (see Apollo Lunar Surface Journal). He wasn’t really surprised, but possibly quite relieved the feather didn’t stick to his glove with static.

I think Scott’s little experiment was one of the most important events of the Apollo programme. Other astronauts had done little stunts (Al Shepard’s golfing is probably the most famous) . Apollo 15 was the first of the fully scientific ‘J’ missions. Scott was the first to drive a lunar rover. He and Jim Irwin undertook three long EVA’s (in addition to Scott’s ‘stand up EVA’ in the top hatch of the LM) with the rover to distant areas in the area of Hadley Rille, sampling the geology of the area and going a very long way to determining the origin of our Moon.

Landing on the Moon and returning home was of course the first target, set by Kennedy in 1961. Achieved by Armstrong, Aldrin and Collins in 1969 this was effectively repeated by Apollos 12 and 14. Apollos 15, 16 and 17 were hugely more complex science focussed missions, and Scott’s Apollo 15 is regarded by many as the best planned and executed of all.
This blog will explore general science, space and astronomy. It may serve as a forum for some debate about current topics. I’ll keep my cycling rants to my cycling blog, Its Passenger is its Engine.


17 Responses to “Why Hammer and Feather?”

  1. edarrell Says:

    Where are the hammer and feather today?

  2. saturn5 Says:

    The hammer is probably exactly where Scott dropped it. The feather likely got blown away (but not too far) by the exhaust of the ascent engine. They didn’t pick them up to bring them home. I think it’s nice to think of important artefacts being in situ rather than in some museum, or being sold to collectors.
    Scott says he brought two feathers with him as he’d intended to try it out first (in case the feather stuck to his hand). He didn’t use it, but we don’t know where the other feather is, and neither does he. I wonder if anyone checked the pockets of his suit?
    I like your blog. Have a look at http://strangemaps.wordpress.com/.

  3. edarrell Says:

    I’ve already looked over strangemaps.com, thank you! It’s a good idea, and I’m wondering how to use it for classroom work.

    I saw your map of Texas at its greatest extent, and that made me wonder if you have a map of Utah as originally proposed for statehood. It was then to be known as “Deseret.” Here’s the only weblink I’ve found: http://www.ldsces.org/inst_manuals/chft/images/28-03.pdf

    Good luck with the blog.

  4. saturn5 Says:

    Strangemaps isn’t mine!

  5. edarrell Says:

    Oops. My error. Well, keep up the good work here . . .

  6. Sophie Says:

    What does the Hammer & Feather experiment prove?

  7. Sophie Says:

    I’m doing research on it and am finding it incredibly difficult to find out what it proves. Can you help me?

  8. Ed Darrell Says:

    It proves that gravity works equally on light and heavy objects. Without air resistance to slow it down, the feather falls at the same rate as the hammer.

  9. kelly Says:

    This is really exciting to know about becoz it tell us that when a heavy or a super light objects falls in space its gravity contain the same energy

  10. saturn5 Says:

    Hi Kelly. Glad to see you enjoyed the post. However, both objects don’t have the same energy (the ‘heavier’ one has more in proportion to its mass), but they do accelerate at the same rate.

    If you’re interested it’s because of Newton’s 2nd Law: F=ma. It is easier to speed up (or slow down) lighter (less massive) things.

  11. John Smith Says:

    h = 1.5 m, g_moon = 1.622 m/s^2, then the free-fall time interval should be t = sqrt(2h/g_moon) = 1.36 sec.
    However, the hammer is in free fall for at most 1.1 seconds.
    Is the moon gravity at that particular location stronger than usual or there is some other explanation?

  12. saturn5 Says:

    See answer on Hammer & Feather II.

  13. Sboniso percival Says:

    This the one of those important things in the world of science to what was happening in the world in the 20s and the 70s till now. this information it helping us as the science student to known feather about science.

  14. Sboniso percival Says:

    Hi i am Percival i am glad to known that the abject will move at the constant velocity unless they is an unbalance force act on it e.g it means that if you got a ball you can throw it in a straight line it will move if the air resistance doesn’t act on it like net force,gravitational force it will continue to move at constant velocity in a straight line.

  15. Sboniso percival Says:

    when an object is falling freely, what happens to the acceleration ,velocity, displacement , speed and distance of the object as it is falling?

  16. saturn5 Says:

    As an object falls in an atmosphere acceleration decreases from an initial 9.8 m/s/s as air resistance increases due to increased speed, speed increases until it reaches a terminal speed where forces of weight and air resistance are balanced.

    Where there is no atmosphere the speed increases at the rate of local g, with no terminal speed. On the Moon this is about 1.6m/s/s.

    This is best illustrated with s/t or d/t graphs. I’m sure you can find them if you look in your textbook.

    You appear to be uncertain of the meanings of speed/velocity, distance/displacement.

  17. tulle tutu Says:

    tulle tutu

    Why Hammer and Feather? | Hammer and Feather

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