This report presents the studies of spacecraft environment planned on SFU (Space Flyer Unit) Mission 1. A diagnostic system to study a spacecraft environment on SFU will consist of vacuum gauges, a mass spectrometer, plasma probes, potential detectors, wave receivers, micro-g meters, a spectrometer, magnetometers, and an electron density fluctuation detector. It also carries test materials to study the surface-space medium interaction which will be recovered and analyzed on the ground. The major objectives of this project are to study; the plasma environment in the wake (why and how plasma is heated in the wake?), the electromagnetic environment in the ram (why there exsists plasma turbulence in the front?), the interaction between gas and plasma (is the critical velocity ionization excited?), and the interaction between high speed space medium and solid (what is the mechanism to excite the shuttle glow?). The results will be applied to the research of the fundamental plasma processes such as a plasma diffusion and a stability, and to the space plasma physics, as well. They will also be applied to predict the environment of larger space structures, such as a space station and a solar power system. The spacecraft environment modified by operating a plasma engine and a high-voltage solar array system will be also studied in SFU Mission 1.