Co-Investigator - The Gamma-Ray Astronomy Team - NASA

2.6.2 ElectricalThe electrical interface presents no complications.The Burst Monitor requires unregulated power,clock, command, and telemetry lines. Communicationwith the LAT, if desired, can be achievedthrough the spacecraft using data in the telemetrypacket, or by a direct interface to the LAT. Thepower requirements are summarized in table 10.The total power is 17.8 watts, without contingency.The required telemetry rate is normally 4 kbps,increasing to 9 kbs during bursts, as was describedin more detail in section 2.2.2.6.3 ThermalThe spacecraft will provide thermal control andinsulation. The MSFC Engineering Directorate willuse thermal radiation analyzer system (TRASYS)and system improved differencing analyzer(SINDA) computer models to support the GRBMthermal and thermal/vacuum testing. Preliminaryanalysis shows the following thermal requirements.Detectors0 to 20 °C operational, –10 to 30 °C storage, stable1 °C over one orbit. The stability requirement isderived from the need for short term gain stability.The AGC can maintain stability over longer times.Electronic Boxes0 to 50 °C operational, –30 to 90 °C storage.2.7 Ground System and Operations2.7.1 Requirements and Operations ConceptThe ground system for the GBM is a hardware andsoftware system that accepts instrument data fromthe GLAST MOC and produces scientific data sets.The system also monitors instrument performanceand safety.The GBM IOC receives data from the instrumentvia the MOC, and converts it into standard low-leveldata products for distribution to the GLAST SOC.The system data flow for GBM is shown infigure 30.Figure 30.—System Data Flow for the GLAST Burst Monitor.42