Reducing the vulnerability of spacecraft against space debris impact requires a thorough understanding of the processes involved in such collisions. This understanding can be gained from the analysis of laboratory experiments using accelerators capable of simulating space debris impacts at the highest velocities currently achievable on Earth. At Fraunhofer EMI, a number of two-stage light gas guns are available that are capable of reaching, depending on the gun, more than 9 km/s with relevant projectile sizes. This paper focuses on the calibre 4 mm two-stage light gas gun, which features a great number of diagnostic methods at target side, including accelerometers, force and pressure gauges, high-speed high-resolution spectroscopy and optical high-speed photography and video. The accelerator is described, and an overview on instrumentation available to systematically measure the occurring phenomena is given.