With the use of the new experimental facility, the High-Energy Density Science (HED) instrument at the European XFEL it will be possible to investigate matter at extreme conditions like those found inside of exoplanets (Appel et al., 2014; Tschentscher et al., 2017). We will be able to study the model system MgO at pressures of up to 1 TPa and several 1000 K through the temporal pulse shaping capability of the optical laser DIPOLE100X, which will allow quasi-isentropic compression of material, reaching off-Hugoniot high pressure states. These states will help us understand the basic compositional and structural properties of large, terrestrial exoplanets, so-called ‘Super-Earths'. Sample design will consist of polycrystal MgO to be deposited as successive coatings directly on a pressure window (LiF). Typical thickness of the sample should be varying from a few µm up to a maximum of 20 µm to ensure homogenous pressure distribution. Specific heating procedures during the process of deposition will enhance the XRD signal. Experimental results will be compared to ab initio hydrodynamic simulations to benchmark experimental key phases at the relevant conditions (Cebulla and Redmer, 2014). Ultimately, we are going to obtain equation-of-state (EOS) data for MgO including its melting curve. First simulations via the hydrocode ESTHER (Colombier et al., 2005) reveal experimental conditions, in which peak pressures of > 6 Mbar and temperatures of more than 10000 K can be achieved for MgO of 5 µm thickness, a 200 µm square pulse, pulse durations of 5 ns, incident beam angle of 20 degrees and consequently laser intensities of over 7e13 W/cm2. The experimental achieved P-T conditions will be equivalent to those in the inner Earth and in larger rocky planets and ultimately help to understand the compositional and structural properties within these objects.