The survey is some 100 times larger than the previous largest map of the web of dark matter, gathered by the Hubble telescope's Cosmic Evolution Survey, or Cosmos.
Dr Massey and his colleagues were able to map the matter (both dark and visible) in the bit of the firmament covered by the Cosmic Evolution Survey by looking for characteristic distortions in the shape of distant galaxies that only Hubble, which is beyond the image-blurring effects of the atmosphere, can see.