Resolving the mysteries of the universe is one of the objective of ESA Space science missions.
One big mystery is represented by what can be called the dark side of space: pitch blackness which is indeed the dominating component of our universe, made up of dark energy, dark matter and the famous black holes.
Thanks to the observations of different telescopes like ESA XMM Newton or Hubble astronomers now have a better understanding of these phenomenae.. and soon the ESA Planck observatory will complement these views on the invisible.