Video: Rosetta scientist Matt Taylor on the end of mission

Six satellites are set to ride a light-class European Vega rocket into orbit from French Guiana on Wednesday night, the first Vega launch since a failure last year that officials attributed to human error.

Engineers suspect a piece of foreign object debris may be intermittently stalling a motor needed to place the Curiosity Mars rover’s drill bit onto rocks, and the robot’s ground team is assessing the source of the potential contamination.

Loaded with three commercial satellites, a European Ariane 5 rocket returned to its launch pad in French Guiana Thursday after a two-week launch delay to resolve a technical issue that forced an abort to a countdown July 31. Arianespace says the mission has been rescheduled for launch Saturday due to unfavorable upper level winds in the forecast for Friday.