Given the task definition and input, reply with output. Given a disfluent sentence, modify the sentence to it to its equivalent fluent form, preserving the meaning of the sentence.

What astronomer or no make that geochemist developed the uranium-lead dating method into lead-lead dating?

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
What geochemist developed the uranium-lead dating method into lead-lead dating?