Congress would do a world of good by making clear to the Fed that its primary mission is sound money.

FORBES: Magazine Article

Curiosity is only about a quarter of the way through its primary mission, so there's lots of time to search for more watery evidence, as well as for any elusive associated organic molecules, which have yet to be found.

CNN: Have a drink on Mars

"With Solis at the helm, we're absolutely confident that the Department of Labor will return to its primary mission of looking out for the health and welfare of America's workers, " said Art Pulaski, executive secretary-treasurer of the California Labor Federation.

NPR: Obama Adds To Cabinet; Warns Of Slow Recovery

Kepler completed its primary three-and-a-half year mission last November, Nasa says, and is now in an extended mission phase.

BBC: Nasa's Kepler telescope hobbled by faulty wheel

The ship is designed to conduct only one primary mission at a time, but its small size, high speed and stealthy design make it well suited to function in treacherous coastal areas where bigger warships seldom venture.

FORBES: Low-Cost Warship Rescues Navy From Shrinking Fleet

Way back in November of 1985, on just its second mission, Atlantis experienced a blow-back of hot gases past the primary O-rings in one of its solid rocket boosters, resulting in serious erosion of said O-ring.

ENGADGET: Space Shuttle Atlantis ends its run of predicting disaster for other NASA shuttles