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In support of the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft that The Johns Hopkins University Applied Physics Laboratory (JHU/APL) is currently building under NASA's Discovery Program, an onboard telecommunication system has been designed and will be assembled at JHU/APL. One of the main components of the system is an X-band solid-state power amplifier (SSPA) operating at 8.433 GHz that supports various downlink antennae including an eight-element phased array. This SSPA subsystem is comprised of over 40 hybrid devices, each of which along with internal matching circuits contains one of the following five different GaAs part types manufactured by Triquint Semiconductor, Inc.: (1) 8810 Metal-Semiconductor Field Effect Transistor (MESFET) Gain Block Amplifier Microwave Monolithic Integrated Circuit (MMIC), (2) 4230 Heterostructure Field Effect Transistor (HFET) Amplifier, (3) 4240 HFET Amplifier, (4) 9083 Pseudomorphic High-Electron-Mobility Transistor (pHEMT) High Power Amplifier MMIC, and (5) 6336 MESFET Phase Shifter MMIC. The hybrid package has been custom-designed at JHU/APL specifically for spaceborne applications. In this paper, we will discuss the 168-hour burn-in and 1000-hour life tests for the hybrids that have been undergoing device screening and space qualification testing. For the approximately 140 samples that were screened in the burn-in test, there were minor shifts in certain device parameters such as the 1-dB compression and power gain, although the DC drain and gate currents showed negligible changes. Such initial parameter shifts are typical of devices settling into their stable long-term useful-life behaviors. At present, the life test is in progress and interim test results will be presented. All preliminary indications point to sufficient device reliability for the MESSENGER space mission. This work demonstrates the viability of employing a blend of proven (MESFET) and recently matured (PHEMT and HFET) technologies for space hardware.