| definition |
- [Source: NASA/JPL, ftp://podaac.jpl.nasa.gov/pub/grace/doc/ProdSpecDoc_v4.5.pdf ]
The GRACE Thruster Activation System is part of the Cold Gas System.
The GRACE Cold Gas System uses Nitrogen as medium, which is stored
in two tanks at an initial pressure of 350 bar. This upstream pressure
is reduced to the thruster valve working pressure of approximately 1.5
bar by a Pressure Regulator. For redundancy reasons, the two branches
can be operated individually. Attitude control around the roll, pitch
and yaw axis is performed by 3 sets of 4 thrusters with a nominal thrust
force of 10 mN. The attitude control thrusters are nominally operated
in pairs which are accommodated such, that force free reaction control
is achieved. For orbit maintenance, two 40 mN thrusters are mounted on
the anti-flight direction side with the force vector pointing through
the satellite center of gravity. The cold gas system housekeeping sensor
set consists of two Pressure Transducers, one for the high pressure part
and one for the low pressure part, and temperature sensors on both tanks
and every thruster.
[Summary from GRACE Thruster Specification Document]
Group: Instrument_Details
Entry_ID: THR
Group: Instrument_Identification
Instrument_Category: Earth Remote Sensing Instruments
Instrument_Class: Passive Remote Sensing
Instrument_Type: Positioning/Navigation
Short_Name: THR
Long_Name: THRuster activation system
End_Group
Group: Instrument_Associated_Sensors
Short_Name: TEMPERATURE SENSORS
Short_Name: PRESSURE TRANSDUCERS
Short_Name: TNK
End_Group
Group: Associated_Platforms
Short_Name: GRACE
End_Group
Online_Resource: ftp://podaac.jpl.nasa.gov/pub/grace/doc/ProdSpecDoc_v4.5.pdf
Creation_Date: 2007-05-02
Group: Instrument_Logistics
Instrument_Owner: USA/NASA
End_Group
End_Group
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