Forgetful Rachel is the second faction mission given by Boris. He tells you that Rachel is having trouble with scientist squatters and she needs help dealing with them.
Rachels instance is actually repeatable. To find it, head over to the mine and look at thw rear of the mine, there should be a path. Follow the path until you find her.
To complete the quest, talk to Rachel. She makes you run her Rachels Folly repeatable intance. Run the instance then report to Boris.