McGroarty celebrated her 30th day of living at the MSI Thursday by helping to light The Christmas Around the World Grand Tree.
The Grand Tree is surrounded by more than 50 trees decorated with holiday traditions from around the world.
McGroarty, 24, won a contest to spend 30 days living inside the MSI. She's spent nights sleeping in the World War II era German submarine, the "Smart Home" and other museum exhibits.