ROCSAT-2 Critical Design Review ISUAL Thermal Interface Design / Analysis Report Jeng-Der (J.D.) Huang ( 黃正德 ) Tsung-Yao (Andy) Chen ( 陳宗耀 ) Jih-Run (J.R.) Tsai ( 蔡志然 )

ROCSAT-2 Contents Thermal Design Description Thermal Analysis Assumptions Configuration Power Dissipation Thermal Analysis Results Results Discussion Thermal Hardware Description Issues and Concerns

ROCSAT-2 Thermal Design Description ISUAL(AP, SP, CCD and AEP) is thermally isolated from the payload platform to reduce the platform’s thermal distortion. The locations of the AEP and IRU had changed in the CDR phase. ISUAL has the independent thermal control to keep the temperatures within their limits. Thermostat controlled heaters are used on ISUAL units to keep the temperatures within their limits in ASH mode. Thermal control devices such as the radiator, MLI and heater are used to maintain the temperatures within their operating/non- operating limits.

ROCSAT-2  The internal heat dissipations of ISUAL units used orbit- averaged values.  The predicted interface temperatures are unit radiator temperatures for worst hot and cold cases.  The units are thermally isolated from the payload platform with interface conductance value of W/°C.  The heat of each unit part is conducted through the screws with conductance values of 0.76 W/°C for M4 type screw and 0.6 W/°C for M3 type.  The conductance between the lens and lens/CCD assembly of CCD Imager is 0.02 W/°C.  The Spectrophotometer filter is insulated from the ring with conductance value of W/°C. Thermal Analysis Assumptions

ROCSAT-2 Configuration STR Array Photometer Spectrophotometer CCD Imager AEP RSI IRU

ROCSAT-2 Configuration (Continued) AEP IRU RSI Spectrophotometer Array Photometer CCD Imager STR

ROCSAT-2 Nominal hot (operating) Power Dissipation

ROCSAT-2 Nominal cold (stand-by) Power Dissipation (Continued)

ROCSAT-2 ASH mode Power Dissipation (Continued)

ROCSAT-2 Radiator area requirement Thermal Analysis Results

ROCSAT-2 Thermal Analysis Results- Radiator and Heater Locations Radiator (Heater with 4 thermostats imbedded) Array Photometer Radiator (Heater with 4 thermostats imbedded) CCD Imager AEP Radiator (Heater with 4 thermostats imbedded) Spectrophotometer

ROCSAT-2 Thermal Analysis Results (Continued) (129, -417, 744) (129, -417, 540) (129, -487, 407) (129, -741, 539) (129, -741, 679) (129, -651, 769) (129, -521, 853) Z Y AEP Radiator Coordinates (Provided by Astrium) Unit: mm

ROCSAT-2 Orbit averaged heater power requirement Thermal Analysis Results (Continued) * Set-point of Thermostat: -25  3  C / -20  3  C, dead-band  4  C

ROCSAT-2 Predicted interface temperatures for nominal hot case Thermal Analysis Results (Continued)

ROCSAT-2 Predicted interface temperatures for nominal cold case (stand-by mode) Thermal Analysis Results (Continued)

ROCSAT-2 Predicted interface temperatures for ASH case Thermal Analysis Results (Continued)  ISUAL instruments are thermally controlled by thermostats in ASH mode.

ROCSAT-2 CCD Imager, Spectrophotometer and Array Photometer survival heaters are controlled by thermostats instead of thermistors, and the dead-bands (the difference between lower and upper temperature set-points) for the thermostats are all 5  C. The top extended surface of the AEP is used as the radiator, and ISUAL total radiator areas are m 2. Both worst hot and cold predicted temperatures of ISUAL are within the maximum and minimum operating/non-operating limits with proper margins by applying radiators and heaters. CCD Imager and Spectrophotometer have more detailed internal thermal models and these can improve the accuracy of interface temperature predictions. Results Discussion

ROCSAT-2 Thermal Hardware Description The thermal filler “Cho-Them” should be applied between the AEP box and radiator to increase the interface thermal conductance. Silver-Teflon SSM (Second Surface Mirror) radiator is applied on unit surfaces to radiate unit waste heat to the space. The ISUAL MLI design has been completed, and the MLI drawings for AEP, CCD Imager, Spectrophotometer and Array Photometer were made by NSPO. These drawings should be reviewed by UCB and then Astrium.

ROCSAT-2 CCD Imager MLI Drawing

ROCSAT-2 CCD Imager MLI Drawing (Continued)

ROCSAT-2 Spectrophotometer MLI Drawing

ROCSAT-2 Array Photometer MLI Drawing

ROCSAT-2 AEP MLI Drawing

ROCSAT-2 Current analysis results are based on very limited unit thermal information. The more detailed analysis must be performed after the following information are given by UCB.  More detailed mass break down for each unit  Clear power profile for each unit in nominal, stand-by, and survival modes  Heat transfer paths inside the units, especially in some critical parts such as lens, filters, etc.  Lens (instrument-controlled) heater operations (i.e., on/off, temperature set point, etc.)  CCD thermoelectric cooler thermal capability NSPO is only responsible for ISUAL unit thermal interface control based on the unit internal thermal information given by UCB, and UCB should be responsible for ISUAL unit internal design and thermal performance. Issues and Concerns