 Glazebrook also developed the open-source Perl Data Language, a perl-based alternative to the commercial IDL.Glazebrook was one of the leaders of the "Gemini Deep Deep Survey" (GDDS) which measured the evolution of galaxies using Gemini Observatory and the Hubble and Spitzer Space Telescopes.The project, along with a number of other studies, determined in 2004 that massive galaxies formed surprisingly early in the distant Universe, explaining why a lot of them appear so remarkably old.