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Introduction
Introduction
The TVAC test is intended to simulate the worst-case conditions for the survival and operations of the satellite in orbit. The thermal balance test sequentially soaks the spacecraft to hot and cold temperatures until a steady state is reached for thermal model calibration/validation. This also tests the performance of hot and cold starts. The thermal cycling test imitates orbital effects by cycling hardware between hot and cold cases.
GSE List
GSE List
The GSE list summarizes the tools, facilities and resources needs to support the verification activities.
o TVAC chamber
o Torque wrench
o Wrench
o MLI blanket
o Temperature sensors
o Kapton
o Copper tape
o DAQ
o Computer
o Multimeter
o Scissors
o Temperature probe unit
o Saddle assembly
Set-up
Set-up
The TVAC test interface plate will be placed within the test hardware location in the chamber. The full spacecraft will then be put on the interface plate supports.
TVAC chamber
TVAC test interface plate
Data Acquisition Unit & Harnessing
Data Acquisition Unit & Harnessing
The harnessing and data acquisition plan was developed as part of a thesis using the same facilities at Magellan. All parts have therefore been previously acquired and set up. The data acquisition unit (DAQ) used is the Keysight 34970A, with Agilent Bench-Link Data Logger software implemented to monitor and record the thermistor data. The data collection harness, which is what connects the thermistors for temperature measurements to the DAQ, uses 104 pin connectors with crimp pins. The thermistors used are Omega bead-type 5 k thermistors (P/N 44007). The thermistors come with uninsulated leads approximately 3 inches long; for integration with the test harness, each lead was soldered to a wire connected to the 104 pin connector. The exposed wires of the leads were placed between two pieces of Kapton tape in order to keep them from shorting together and provide insulation from the rest of the apparatus.
DAQ used to read and record thermistor outputs for TVAC testing
Close up view of thermistor with leads soldered to connector wires and Kapton tape for electrical insulation
The wires soldered to the thermistor leads are connected to the P3 connector using crimp pins. P3 is connected to J3. Both are inside of the chamber feedthrough. The signals from J3 are transferred to P4. The wires from the mating connector J4 on the outside ofthe chamber were then connected to the DAQ through screw terminals connections in DAQ cards.
DAQ and DAQ card
MLI Blanket
MLI Blanket
To minimize the radiative heat transfer between the TVAC chamber wall and the CubeSat, the CubeSat will be wrapped in MLI. This will minimize the temperature gradient across the CubeSat structure.
CDH Connection for Reduced Functional Test
CDH Connection for Reduced Functional Test
TBD
Thermistor Locations
Thermistor Locations
During the functional test, the spacecraft will be powered on and CDH will have temperature reading available from the flight thermistors.
During the test itself, the DAQ will be logging the temperature of critical hardware and/or location for thermal model calibration and validation.
Test Parameters
Test Parameters
Below is a diagram of the TVAC test phases. It follows the order of the spacecraft level testing outlined in the full spacecraft AIT test plan. The thermal balance and thermal cycling parameters are in the tables below.
Reduced System Level Functional Test (F*) - Due to no physical access into the TVAC chamber, the Iris team will not be able to test and reset the deployables between steps 6 through 9. However, all other functional test activities will be undertaken to demonstrate a working satellite during each thermal plateau vacuum environments.
Procedure
Procedure
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