(written from a Production point of view)
Jennings was an art director on Star Trek: Phase II, the television project that was to become Star Trek: The Motion Picture, ultimately earning him an Academy Award nomination. He, along with Production Illustrator Michael Minor, was the co-designer of the refit-USS Enterprise for that project, after he was brought in June 1977 on recommendation of Matt Jefferies. Jefferies had declined to return permanently to the Star Trek franchise, though he had on a temporary basis done preliminary design work for the project, and from which Jennings and Minor proceeded. Prior to this assignment he had been Jefferies' (uncredited) assistant during the second season of Star Trek: The Original Series, befriending both Matt and brother John Jefferies. (Star Trek Phase II: The Lost Series, pp. 26-28) When the movie was upgraded to a motion picture project in October 1977 they were to be joined by Robert Abel and Richard Taylor, and in a later stage by Andrew Probert. To the unsuspecting Jennings the upgrade, of which he was informed on 21 November 1977, was something of a nasty surprise, as he recalled decades later, mellowed but still not amused, "We were within two weeks of starting the new series, and somebody said, "Wheeew, let's make a motion picture!" Just like it was a whole different thing, you know. They've always thought that about the TV people. We did something, sort of down here and they did things that were sort of up there, that we could not do up here, what they did down there, whatever!" (Star Trek: 45 Years of Designing the Future)
As far as Jennings was concerned, the situation on what was now The Motion Picture grew from bad to even worse, as Robert Abel & Associates, the company brought in for the visual effects for the movie, was allowed to establish a by Taylor headed art department in January 1978, Astra Image Corporation, to serve alongside his own art department resulting in confusing situations with hugely overlapping responsibilities. Not only this, but from the start there was intense strive and conflict between the two art departments as Astra was perceived, by Jennings and Minor in particular, as performing a power grab by aggressively trying to assert total creative control. Minor elaborated, "It wasn't long before the Abel group started doing their own designs for what they thought the whole feature should look like. Not just the special effects, mind you; they wanted to upgrade everything. They wanted to control the design of the costumes, the sets, effects, everything. They were like an octopus. And it was not a fair ball game, in my opinion. They would spend long hours closeted with Paramount brass, and yet the art department – would get maybe 30 minutes to show off what we were trying to do. So, we knew something was in the works."
Four years later, Jennings, still thoroughly chagrined, added, "We made a camel. It started out to be a horse, but a committee got hold of it. Everyone got into the act on that movie. There was creative pulling back and forth, fumbling around, coming and going of people ad infinitum and ad nauseam. Everyone who worked on the art direction provided too much input to be ignored, so we all got credit, and Hal Michelson, brought in as art director, ended up getting credit as production designer." The situation finally came to a head in early March 1978, when Jennings, fed up with Astra, either decided to leave the production or was let go, as related by Unit Production Manager Phil Rawlins, "Joe Jennings was still with the project when I came on. Joe is a good Hollywood art director, and the reason he left the picture is because Bob Abel and Richard Taylor wanted complete creative control of the look of the picture. They just kept complaining about the sets and complaining about the sets until Joe had to leave the movie." Jenning's close co-worker Minor, was even more vehement in his appraisal of the situation, which was co-responsible for the production of the movie becoming fraught with delays, confusion, and difficulties, "It was one of the most soiled and shabby chapters of Hollywood history, in terms of how people were treated. The trouble, as always, was that the wrong people were in charge. We're in a business in which the people at the top, who make the decisions, really don't know a damn thing about making pictures. I think we all knew then that we were associated with a bomb. It's too bad the movie happened at all." Later that month Michelson filled the position, vacated by Jennings, as – adding insult to injury to Jennings – "Production Designer", instead having to settle for the latter's lesser desirable, and thus lesser paid, "Art Director"-title. (Return to Tomorrow - The Filming of Star Trek: The Motion Picture, pp. 71-72; Cinefantastique, Vol 12 #5/6, p. 58)
Jennings was also the production designer for Star Trek II: The Wrath of Khan, partially responsible for the design of the Miranda-class studio model. For this, he and Minor were credited as the "sole inventors" on design patent No. D272839 (there called a "toy spaceship"), issued by the US Patent and Trademark Office to Paramount Pictures on 28 February 1984.
He was less than enthusiastic about Nicholas Meyer's ideas to make Star Trek more militaristic in Star Trek II, and thought the torpedo bays were simply ridiculous – as they should be fired directly from storage. In an interview in the Star Trek II Director's Edition DVD special feature, "Designing Khan", he has stated that seeing the ensigns with hooks pulling the grating off the torpedo conveyor before launching it drove him crazy, since any real ship that took that long to load weapons would probably be destroyed in about ten seconds. Concurrently, he considered the battle between the Enterprise and USS Reliant, originally scripted as pounding at each other at close range in open space – likening it to a man o'war slugging match from the era of sail and, ironically, exactly portrayed as such in the 2011 version of The Three Musketeers in which the Star Trek battle was paraphrased – ludicrous, pointing out that, more realistically, spaceships would go at each other in high-speed passes under open space circumstances (as was adopted in the Battle of Wolf 359 and Dominion War battle scenes in their respective, later Star Trek: Deep Space Nine episodes, as well as in the Star Trek: The Next Generation films, most notably Star Trek: First Contact). Together with Minor, he came up with the concept of the Mutara Nebula knocking out both ship's navigational and tactical systems as a more believable rationale for the slower-paced close quarter combat between the two vessels, which was ultimately accepted by the writing staff. After the sequence was filmed, Jennings gleefully recalled Meyer's reaction, "You were right. Thanks for not saying so!" (Star Trek: 45 Years of Designing the Future) Coincidentally, his concerns with the torpedo bay were later addressed by Meyer in Star Trek VI: The Undiscovered Country, where it was indeed strongly implied that torpedoes were fired directly from storage in scene 55 in which Captain Montgomery Scott uttered the line, "Negative, captain. According to inventory we're still fully loaded.", after the Kronos One was unexpectedly hit by a torpedo volley from the Enterprise's torpedo bay.
As already indicate above, while working on the two Star Trek features, Jennings enjoyed a particularly close and enduring working relationship with former protégé Mike Minor, for whom Jennings had arranged one of his first jobs in the motion picture industry on the television show Gunsmoke. Brought in on the Phase II project and its follow-up by Jennings, an appreciative Minor later stated, "We worked together like Rogers [sic.] and Hammerstein." (Cinefantastique, issue 44, Vol 12 #5/6, p. 58)
On 27 September 2009, Joe Jennings, together with fellow designers John Jefferies, Herman F. Zimmerman and Scott Chambliss, were honored for their Star Trek contributions in a media event called the "Star Trek Designers Talk Trek History At Art Directors Guild Event" at the Egyptian Theater in Hollywood, and in which all designers discussed in-depth their work on the franchise. The event was moderated by another Star Trek alumnus, Daren Dochterman. 
Career outside Star Trek
Besides Star Trek, Joe Jennings' additional art direction credits included the television shows Gunsmoke and Project U.F.O. and such films as Kansas City Bomber (1972, featuring Georgia Schmidt) and Gone with the West (1975, starring Robert Walker, with makeup by Fred B. Phillips). He was also production designer on the films Yellowbeard (1983, starring Kenneth Mars) and Johnny Dangerously (1984, starring Joe Piscopo and Ray Walston), the 1986 mini-series North and South, Book II (starring Kirstie Alley, Mary Crosby, Jonathan Frakes, Jim Metzler, Leon Rippy, William Schallert, Jean Simmons, Kurtwood Smith, David Ogden Stiers, and Anthony Zerbe, with costumes by Robert Fletcher), and the television movie Ironclads (1991, starring Virginia Madsen). The 1992 television movie The Jacksons: An American Dream was Jennings' last recorded motion picture credit.
Apart from his Star Trek Academy Award nomination, Jennings also received Emmy Award nominations for his work on the mini-series Roots (1977, starring LeVar Burton, Thalmus Rasulala, John Schuck, Madge Sinclair, and Ben Vereen) and NBC's Shogun (1980, featuring John Rhys-Davies and W. Morgan Sheppard and narrated by Orson Welles; with cinematography by Andrew Laszlo and on which he immediately embarked upon after The Motion Picture). He shared the latter nomination with set decorator Tom Pedigo.
Star Trek interviews
- "Behind the Scenes: The Art Department", Star Trek: The Magazine Volume 3, Issue 5, September 2002, pp. 66-73
- Star Trek II: The Wrath of Khan (The Director's Edition) special feature, "Designing Khan" (2002)
- Star Trek: 45 Years of Designing the Future (2009)
- The Making of Star Trek: The Motion Picture, March 1980
- "Star Trek: The Wrath of Khan", Kay Anderson, Cinefantastique, Vol 12 #5/6, 1982, pp. 50-55, 57-61, 63-68, 70-74
- Star Trek Phase II: The Lost Series, March 1997
- Return to Tomorrow - The Filming of Star Trek: The Motion Picture, December 2014
Joe Jennings received the following Academy Award nomination in the category "Best Art Direction-Set Direction":
- 1980 for Star Trek: The Motion Picture, shared with Harold Michelson, Leon Harris, John Vallone, and Linda DeScenna