| definition |
- [Source: GFZ/Potsdam, http://www.gfz-potsdam.de/ ]
The Star Camera Assembly (SCA) (also called Star Camera System or SCS) will be manufactured (as for CHAMP) by the Danish University of Technology (DUT) and is used for the precise orientation of the satellite within the AOCS and for the correct interpretation of the ACC measurements. The SCA consists of 2 simultaneously operated DTU star cameras with a field of view of 18° by 16° and one Data Processing Unit (DPU). It will measure the S/C's attitude better than 0.3 mrad (with a goal of 0.1 mrad) by autonomous detection of star constellations using an onboard available star catalogue. The SCA is rigily attached to the accelerometer and views the sky at 45° angle with respect to the zenith at the port and starboard sides. In the case that the sun will move into the field of view of one of two sensors the second sensor will proceed to measure the attitude. To avoid velocity induced aberration the SCA is equipped with an orbit propagator which will be regularily updated by the GPS navigation solution.
Group: Instrument_Details
Entry_ID: GRACE SCA
Group: Instrument_Identification
Instrument_Category: Earth Remote Sensing Instruments
Instrument_Class: Passive Remote Sensing
Instrument_Type: Photon/Optical Detectors
Instrument_Subtype: Cameras
Short_Name: GRACE SCA
Long_Name: Star Camera System
End_Group
Group: Associated_Platforms
Short_Name: GRACE
End_Group
Group: Spectral_Frequency_Information
Wavelength_Keyword: Visible
End_Group
Online_Resource: http://www.csr.utexas.edu/grace/spacecraft/sis.html#sis2
Online_Resource: http://www.gfz-potsdam.de/portal/
Creation_Date: 2009-08-14
Group: Instrument_Logistics
Instrument_Owner: USA/NASA
End_Group
End_Group
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