That year, the team journeyed to the Arctic Circle in the Arctic on Earth. After they arrived aboard the transport Arctic One, they found the debris of an alien ship. Rooney, Drake and Moninger also found the body of a Borg drone, concealed under ice. A short time later, Rooney found another body under the snow.
The team decided to build a base camp to study the two Borg drones and also the fragments of the alien ship. Rooney scanned several of the debris pieces and found proof, inside the glacier, that these pieces were over 100 years old. Later outside, Rooney discovered the ship's transwarp coil while talking to Drake. The two went back to the research module when they heard screams and saw the fire of a phaser rifle.
They found Moninger inside the module, under some equipment. When Rooney turned around to get a medical kit, she almost ran into a Borg drone.
Assimilated by the Borg, Rooney herself became a Borg drone. Aboard the assimilated Arctic One, she tried to stop Captain Jonathan Archer and Lieutenant Malcolm Reed, an away team from Enterprise NX-01, but was fired upon with a phase-pistol. Archer then identified her as one of the researchers from the arctic team.
Background information Edit
In the script for "Regeneration", Rooney was described as an engineer in her thirties, during the events of the story.
In an audio commentary for "Regeneration" on ENT Season 2 Blu-ray, Bonita Friedericy and John Billingsley joked that Friedericy got the part of Rooney by sleeping with Tucker actor Connor Trinneer. In reality, Friedericy auditioned for the role of Rooney, but when she walked into the room to audition, Star Trek: Enterprise creators and Executive Producers Rick Berman and Brannon Braga pretended not to know her. "It was very unnerving, because I'm very shy and I didn't know whether I should say hello or not," Friedericy explained. "So, I sort of waved at them and they both kind of looked distastefully at me, and looked up at the ceiling and then they said, 'Go,' and I thought I wasn't gonna get it, and it was sad, but then I got the call and I got it."
For a scene in which Rooney is at a console in the background, Friedericy tried to make it seem as if her character was as busy as possible, without becoming distracting for the audience. She also tried to imply subtext that Rooney was having an affair with Drake.
On the set, Bonita Friedericy was referred to as a Borg baby. "I was called the baby Borg because Borg are never little, and I'm five-foot-three," she remarked. Applying the Borg makeup to Friedericy for Rooney's assimilated appearance took five-and-a-half hours. This was longer than usual because the makeup team, not having done any Borg for a while, initially made a mistake with Rooney's Borg makeup. To portray the assimilated Rooney, Friedericy also wore a Borg costume that Roxann Dawson had previously wore, in VOY: "Unimatrix Zero". Once Friedericy was made to look Borg, it was time for her to go before the cameras as the assimilated Rooney. Filming the character's death scene didn't require a stunt performer. "I was really pleased with myself," she reminisced, "because they squibbed me [repeatedly], and I did my own stunt." Each time Friedericy performed the stunt sequence, John Billingsley applauded her from off-camera. (ENT Season 2 Blu-ray, "Regeneration" audio commentary)
Her arctic archaeology team coat from "Regeneration" was later sold off on the It's A Wrap! sale and auction on eBay.  Her Borg costume was sold off at the 40 Years of Star Trek: The Collection auction at Christie's.