The further away you look, the greater the redshift. So as well as getting some sense of the distance from that redshift, those measurements will also give us some idea of how the universe has evolved over time. Other spacecraft and surveys have previously looked at similar things. I'm wondering what Euclid is doing that hasn't been done before. How could it add to the information that we already have about dark energy, dark matter? One of the primary targets of Euclid is an effect called gravitational lensing.