Since October 2013 the NASAESA Hubble Space Telescope has been observing some of the most massive structures in the Universe -- galaxy clusters. Using the magnification effect caused by their mass, Hubble can look deeper into the Universe than ever before. In this new Hubblecast, Dr J talks about the goals and the achievements of this campaign, called the Frontier Fields programme. br br You can subscribe to the Hubblecasts in iTunes, receive future episodes on YouTube or follow us on Vimeo. br br Many other Hubblecast episodes are also available. br Find out how to view and contribute subtitles for the Hubblecast in multiple languages, or translate this video on dotSUB. br br More information and download options: br br Subscribe to Hubblecast in iTunes! br br Receive future episodes on YouTube by pressing the Subscribe button above or follow us on Vimeo: br br Watch more Hubblecavideo.webcategory.allst episodes: br br Credit: br Directed by: Mathias Jäger br Visual design and editing: Martin Kornmesser br Written by: Rebecca Louise Davies, Carl Mundy br Presented by: Joe Liske (Dr J) br Narration: Sara Mendes da Costa br Images: NASA, ESA and the HST Frontier Fields team (STScI); S. Rodney (John Hopkins University, USA) and the FrontierSN team; T. Treu (University of California Los Angeles, USA), P. Kelly (University of California Berkeley, USA) and the GLASS team; J. Lotz (STScI) and the Frontier Fields team; M. Postman (STScI) and the CLASH team; and Z. Levay (STScI) br Videos: NASA, ESAHubble br Animations: NASA, ESAHubble, M. Kornmesser, L. Calçada br Music: STAN DART (www.stan-dart.