Northup joined the faculty at the University of New Mexico. At the UNM she started the Subsurface Life In Mineral Environments (SLIME) team. In particular, Northup studies the colourful ferromanganese deposits that line the walls of Lechuguilla and [https://www.nps.gov/media/photo/gallery-item.htm?id=00BDA79B-155D-451F-6737D552DE9FFADC&gid=002834EA-155D-451F-6776BADA00BE0B71 Spider Cave] in Carlsbad Caverns National Park. Her work on the Lechuguilla Cave was featured in a PBS Nova episode, "The Mysterious Life of Caves." She is also interested in the hydrogen sulphide cave (Cueva de las Sardinas) in Tabasco.
Northup was elected Fellow of the National Speleological Society in 1992, and awarded their Science Prize in 2013.