Rafaela's father was a member of the Spanish defence force, so much of her childhood was spent on US military bases. She had a great interest in science and attended Mediterranean University of Science and Technology in Valencia, Spain, gaining a bachelor of science in computer systems engineering. She then achieved a PhD in astrophysics at the University of California, Berkeley.
After graduation, she was offered an internship with the United States Air Force, taking the attention of Lt. Colonel Samantha Carter who recommended that she take a position at Area 51. When regular contact began with Atlantis, she was offered a position and accepted it.
She was part of Dr. Rodney McKay's team, exploring the city to shut down certain sections so that it could not drain the only Zero Point Module they have quickly. They stumbled upon a lab, which housed an Ascension machine, where McKay was "zapped" and gained super-powers, including mind reading. He was with Ronon Dex when they passed her. McKay read her mind and thought that she thinks McKay is "hot"; when she grew flustered, he decided she must have been referring to Ronon. However, Esposito denied it, and hastily walked out due to embarrassment. (SGA: "Tao of Rodney")