It took far too long for Star Trek: Strange New Worlds' Nurse Christine Chapel (Jess Bush) to become a Doctor in Star Trek: The Motion Picture. Doctor Christine Chapel (Majel Barrett) appeared in the first of the Star Trek: The Original Series movies, set nearly 20 years after the events of Strange New Worlds. Doctor Chapel was assigned to the refitted USS Enterprise as Chief Medical Officer under Captain Will Decker (Stephen Collins), however her promotion was short-lived, thanks to the V'Ger crisis and the return of Dr. Leonard "Bones" McCoy (DeForest Kelley).
Despite this, Dr. Chapel continued to fulfill a valuable role within Starfleet, most notably in Star Trek IV: The Voyage Home, when she coordinated the relief efforts in response to the ecological disaster caused by the "Whale Probe". Strange New Worlds is showing just how ready Chapel already was to take this next step in her career. She's smart, capable, and regularly deputizes for Dr. Joseph M'Benga (Babs Olusanmokun). However, the character's established arc in Star Trek: The Original Series, and real-world production issues stand in the way of Chapel's well-deserved promotion.
Nurse Chapel Waits Too Long To Become A Doctor in Star Trek
Star Trek: Strange New Worlds revealed that Chapel was serving aboard the USS Enterprise from 2259, almost two decades before Star Trek: The Motion Picture. In Star Trek: The Original Series, it's established that Chapel didn't officially Starfleet until some time after 2261. Currently, Chapel is serving aboard the USS Enterprise on civilian exchange, although this has rarely been mentioned since the SNW pilot. It's possible that Strange New Worlds will ignore Chapel's TOS continuity in of when she ed Starfleet, but TOS canon has firmly established that she remains a Nurse throughout both Pike and Kirk's five-year missions, until the mid 2270s.
Star Trek: Strange New Worlds has established that Nurse Chapel worked alongside two of the USS Enterprise's most notable Doctors - "Bones" McCoy and Joseph M'Benga. The experience that Chapel would have gained from working with these two men would be invaluable in forging her own career progression within Starfleet Medical. While it's unclear exactly why it takes Chapel so long to make the decision to pursue her MD, there are some real-world and in-universe explanations for why such a capable and intelligent medical officer didn't progress within Starfleet until the 2270s.
Why Nurse Chapel Doesn’t Become A Doctor Until Star Trek: The Motion Picture
The main reason that Chapel didn't progress past the role of Nurse in Star Trek: The Original Series is purely down to TV production of the time. As a network TV show seeking syndication, huge changes to the status quo aboard the USS Enterprise would hamper the ability to sell out of sequence episodes to regional broadcasters. Unlike Star Trek: Strange New Worlds, which is also episodic, TOS rarely had overarching character plots, due to the more ephemeral nature of network TV in the years before home video. Star Trek being canceled in 1969 didn't help matters either, as it would be another decade until the crew of the Enterprise continued their live-action adventures.
The other possibility for the long wait for Star Trek: Strange New Worlds' Chapel to become a Doctor could also be down to her own loyalty to the crews of both Pike and Kirk's Enterprise. Studying for her MD would presumably require her to leave the Enterprise behind. As the Enterprise is part of Chapel's life for the best part of two decades, it's easy to see how she might want to wait until Kirk is promoted to iral and the Enterprise crew are separated before successfully attaining her MD.
Star Trek: Strange New Worlds season 2 premieres Thursday, June 15, on Paramount+.