The Structural/Thermal Test Model (STM) of ESA's Integral gamma-ray observatory was tested at ESTEC during June-September 1998. Following the thermal-vacuum testing in the Large Space Simulator (LSS), the STM (divided into its Payload Module and Service Module) underwent mass property measurements in the Multi-shaker area, and was then moved into the Large European Acoustic Facility (LEAF). Integral is planned for launch in 2001 to perform fine imaging and spectroscopy of 15 keV to 10 MeV celestial gamma-ray sources. [Image Date: 1998/09] [98.09.017-006]