@prefix skos: <http://www.w3.org/2004/02/skos/core#> .
@prefix ns0: <http://gcmd.gsfc.nasa.gov/kms#> .

<https://gcmd.earthdata.nasa.gov/kms/concept/11208f10-6879-48ca-919c-88558391403b>
  skos:prefLabel "Accelerometers"@en ;
  a skos:Concept ;
  skos:narrower <https://gcmd.earthdata.nasa.gov/kms/concept/11c1598b-d484-4c26-83ae-bc12af957b84> .

<https://gcmd.earthdata.nasa.gov/kms/concept/11c1598b-d484-4c26-83ae-bc12af957b84>
  skos:changeNote """2019-07-16 06:25:48.0 [mmorahan] Cut Concepts 
delete broader relation (null); 
add broader relation (EGG [11c1598b-d484-4c26-83ae-bc12af957b84,346357] - Trash Can/Instruments [4b2630a8-2630-42f1-852f-772e9a62efe7,354157]); 
""", """2019-07-16 06:26:58.0 [mmorahan] Move Concepts 
delete broader relation (null); 
add broader relation (EGG [11c1598b-d484-4c26-83ae-bc12af957b84,346357] - Accelerometers [11208f10-6879-48ca-919c-88558391403b,346347]); 
""" ;
  ns0:altLabel [ ] ;
  skos:definition """[Source: ESA's Gravity Mission GOCE Brochure, http://esamultimedia.esa.int/docs/BR209web.pdf ] 

The principle of operation of the gradiometer relies on  measuring the forces that maintain a ‘proof mass’ at the centre  of a specially engineered ‘cage’. Servo-controlled electrostatic  suspension provides control of the ‘proof mass’ in terms of  linear and rotational motion. Three pairs of identical  accelerometers, which form three ‘gradiometer arms’, are  mounted on the ultra-stable structure. The difference between  accelerations measured by each of two accelerometers (which  are about 50 cm apart), in the direction joining them, is the  basic gradiometric datum. The average of the two accelerations  is proportional to the externally induced drag acceleration  (common mode measurement). The three arms are mounted  orthogonal to one another: one aligned with the satellite’s  trajectory, one perpendicular to the trajectory, and one  pointing approximately towards the centre of the Earth. By  combining the differential accelerations, it is possible to derive  the gravity gradient components as well as the perturbing  angular accelerations.  


Group: Instrument_Details
   Entry_ID: EGG
   Group: Instrument_Identification
      Instrument_Category: In Situ/Laboratory Instruments
      Instrument_Class: Magnetic/Motion Sensors
      Instrument_Type: Accelerometers
      Short_Name: EGG
      Long_Name: Electrostatic Gravity Gradiometer
   End_Group
   Group: Instrument_Associated_Sensors
      Short_Name: ACCELEROMETERS
   End_Group
   Group: Associated_Platforms
      Short_Name: GOCE
   End_Group
   Online_Resource: http://esamultimedia.esa.int/docs/BR209web.pdf
   Online_Resource: http://www.esa.int/esaLP/ESAHTK1VMOC_LPgoce_0.html
   Creation_Date: 2009-05-15
   Group: Instrument_Logistics
      Instrument_Start_Date: 2009-03-20
      Instrument_Owner: ESA
   End_Group
End_Group"""@en ;
  skos:prefLabel "EGG"@en ;
  skos:inScheme <https://gcmd.earthdata.nasa.gov/kms/concepts/concept_scheme/instruments> ;
  skos:broader <https://gcmd.earthdata.nasa.gov/kms/concept/11208f10-6879-48ca-919c-88558391403b> ;
  a skos:Concept .