The phrase "a complex mission" is correct and usable in written English.
You can use it to describe a task or objective that involves multiple intricate elements or challenges.
Example: "The team was assigned a complex mission that required careful planning and coordination among various departments."
Alternatives: "a complicated task" or "a challenging objective."
Alison Cronin, who runs the Ape Rescue Centre at Monkey World in Dorset, embarked on a complex mission to rehouse the primate in the south-west of England.
Academic hospitals, after all, have a complex mission that requires them to make tradeoffs between patient care, medical research and training.
Later, he also said he might recommend that U.S. troops provide "close combat advising" to Iraqi forces if they were to attempt a complex mission, such as retaking the northern city of Mosul from the Islamic State.
But as he was promoted to the top job, he faced the challenge of pursuing a complex mission when much of the essential capacity was subject to his influence but by no means under his control.
Having been a UN commander in Bosnia and deputy supreme allied commander in Nato, Smith told students in the annual King's College War Studies Lecture earlier this week that Nato was never designed to devise the strategy and execute it for such a complex mission as the war in Afghanistan.
Meetings require us to engage in joint attention, which makes them better than digital tools for synchronizing approaches to a complex mission.
"It's a milestone that caps off several years of preparation for any complex mission – designing, building and testing the ground systems, preparing the flight operations procedures and then finally an intensive period of team training".
"It's hard to think of a more complex mission than an amphibious raid into strongly held enemy territory," said Gen. Carter F. Ham, the retired head of the military's Africa Command, who noted that he had not been briefed on the details of the operation.
"If you look at the spacecraft and count the number of instruments on it, very quickly it's apparent that this is a very complex mission," said Dwayne A. Day, a space policy analyst at the National Research Council.
Mr. Day added that the Russian approach of undertaking a large, complex mission after years with no projects at all contrasted sharply with NASA's strategy, which includes some smaller missions.
"The only way we can be sure we have found life on Mars is to bring samples back to Earth, and that will be a very complex mission," said Cordey.
