'ongoing mission' is correct and usable in written English.
You can use it when referring to a task or series of tasks which are not yet complete. For example: "The team is currently on an ongoing mission to find a cure for the disease."
I dunno, think World Service, ongoing mission to serve, whatever works".
All this is part of the Flaming Lips' ongoing mission to "do [things] some other way", saying farewell to the "boring... old way" of making albums.
Her ongoing mission: to explore strange new worlds, to seek out new life forms and new civilizations, to boldly go where no one has gone before.
Ongoing, "Mission Control: From the Space Race to the Space Shuttle," an interactive exhibition exploring the Mercury, Gemini and Apollo projects and the current shuttle program.
Cosying up with a major retailer, Brett tells us, is actually part of his ongoing mission to bring the outside in.
Picasa's product "complements Google's ongoing mission to organize the world's information and make it universally accessible," said Jonathan Rosenberg, Google's vice president for product management.
Of course, an ongoing mission of popular culture is to absorb and humble iconic art, as with inflatable toy versions of Edvard Munch's "The Scream".
One ongoing mission is undiplomatically called Operation Fiela, a word meaning "sweep away dirt" or "clean up" in the Sotho family of languages.
Attempts by scientists to grow organs from one species inside another is an ongoing mission: among previous efforts, scientists have grown a rat pancreas inside a mouse.
With it behind us, Stanford can devote its attention fully to its ongoing mission of teaching and research on the frontiers of knowledge.
Events such as the kick-off dinner help fulfill the program's ongoing mission of increasing awareness about medical career opportunities and fostering career-long mentorships with HMS faculty.
