Winkless was born in Dundalk, Ireland, to engineer father Jackie and theatre director mother Rosemary. She received her B.A. (mod) in Physics with Astrophysics from Trinity College Dublin, worked at NASA's Kennedy Space Center, then returned to school for her M.Sc. in Space Science from University College London. After completing her studies she worked in the Materials Team at the National Physical Laboratory for seven years, with a focus on thermoelectric energy harvesting. She researched the use of nanomaterials in the space industry for the European Space Agency.