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Instrument: GRACE SCA : Star Camera System
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Associated Platforms
GRACE

Spectral/Frequency Information
Wavelength Keyword: Visible

Related Data Sets
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Description
[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.

Online Resources
http://www.csr.utexas.edu/grace/spacecraft/sis.html#sis2
http://www.gfz-potsdam.de/portal/

Instrument Logistics
Instrument Owner: USA/NASA

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