5.6 Testing and Verification
189
Fig. 5.18 Diagram of the test article of heat shield in space environment simulator. 1 Heat sink; 2
Infrared lamp; 3 Test article; 4 Support
residual gas inside the test article, the internal pressure of the vacuum system should
be reduced to the order of 10
−3 Pa for a certain period of time. Because of the
high temperature outgassing of the heat shield material, the pressure of the space
environment simulator would increase during the test, which was relevant to volume
of space environment simulator and capacity of vacuum system.
Differences in the operating conditions of the engine might result in deviations
in the nozzle temperature. In order to cover the possible temperature conditions on
the orbit, the surface temperature of the heat shield should be biased in the test. In
addition, the temperature changes in different parts of the heat shield were related to
operation time of the engine. It should be considered that the operation time of the
engine should be biased in the test. A set of typical temperature response curves for
vacuum performance test of the high temperature heat shield of the Chang’E-3 lunar
lander is shown in Fig. 5.19.