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Fwd = Mars Express Strikes A Musical Note

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  • Frits Westra
    Forwarded by: fwestra@hetnet.nl (Frits Westra) Originally from: baalke@jpl.nasa.gov Original Subject: Mars Express Strikes A Musical Note Original Date:
    Message 1 of 1 , Nov 2, 2001
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      Forwarded by: fwestra@... (Frits Westra)
      Originally from: baalke@...
      Original Subject: Mars Express Strikes A Musical Note
      Original Date: Fri, 2 Nov 2001 09:59:58 -0800 (PST)

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      ESA Science News
      http://sci.esa.int

      02 Nov 2001

      Mars Express strikes a musical note

      Listen to the soundtrack accompanying this image and you may think
      it reminiscent of some avant-garde music. The sound is, in fact,
      representative of the vibration the Mars Express spacecraft will
      experience during launch.

      "The machine the spacecraft is sitting on moves up and down like a
      po-go," explains Don McCoy, assembly, integration and verification
      manager from ESTEC, who accompanied the spacecraft during recent tests
      at Intespace, the company responsible for testing the Mars Express
      spacecraft, in Toulouse, France. The tests were designed to check
      that Mars Express will be able to withstand the incredible noise and
      vibration generated during launch.

      The po-going machine starts off at very low frequency, six cycles per
      second or 6 Hz, and gradually increases to 100 Hz. At first, the
      frequency is too low to be heard, but it quickly increases until the
      spacecraft begins to resonate, and make a lot of noise, at about 45 Hz.
      As the frequency increases further, the spacecraft begins to vibrate so
      rapidly that it appears stationary. At 73 Hz there's a second resonance
      and the noise builds to a crescendo. Then from 75-100 Hz it quietens
      down. In the background, throughout the piece, is the rhythmical swish
      of a valve opening and closing periodically, like the brush of cymbals
      keeping the beat.

      During resonances, the acceleration of the spacecraft walls is
      considerable. "A fly on a panel of the spacecraft would find it hard
      to keep its footing. An acceleration many times that of gravity would
      be pushing it off," says McCoy.

      The Mars Express spacecraft has now completed its phase of mechanical
      testing at Intespace and has returned to Alenia in Torino, Italy, for
      integration of the flight models of the instruments and the spacecraft
      electrical equipment.

      USEFUL LINKS FOR THIS STORY

      * Listen to the 'music' of the Mars Express spacecraft
      http://spdext.estec.esa.nl/content/searchvideo/searchresult.
      cfm?aid=9&cid=32&ooid=28814&returnto=1&ftitle=&customsearch=0
      * More about Mars Express
      http://sci.esa.int/marsexpress

      IMAGE CAPTION:
      [http://sci.esa.int/content/searchimage/searchresult.
      cfm?aid=9&cid=12&oid=28859&ooid=28861]
      The Mars Express spacecraft during its vibration tests at Intespace,
      Toulouse.


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