What is the universe made of? Is most of the visible matter just atoms, or is there something else, like dark matter? Do we know all the particles that are out there? Why do galaxies rotate at the speed they do? These and other questions are part of what we think about every day. We try to complete the puzzle with the missing pieces of the new particles. And did you know that the answer to these questions can be studied with detectors not in space, but on Earth? In our lab we have built a Xenoscope, a prototype for a future detector that will be shielded with 50 tonnes of liquid xenon very deep inside the mountain. This prototype is 2.6 m long and contains almost half a tonne of xenon. It will allow us to study the purification of xenon to have a clean target material and how to detect the light and electrons produced in xenon detectors.