STS-51-D
[2] The launch of STS-51-D from Kennedy Space Center (KSC), Florida, on April 12, 1985, was delayed by 55 minutes, after a boat strayed into the restricted Solid Rocket Booster (SRB) recovery zone.Griggs and Hoffman performed an unscheduled Extravehicular Activity (EVA) to attach homemade "Flyswatter" devices to the shuttle's Remote Manipulator System (Canadarm).Discovery's other mission payloads included the Continuous Flow Electrophoresis System III (CFES-III), which was flying for sixth time; two Shuttle Student Involvement Program (SSIP) experiments; the American Flight Echo-cardiograph (AFE); two Getaway specials (GASs); a set of Phase Partitioning Experiments (PPE); an astronomical photography verification test; various medical experiments; and "Toys in Space", an informal study of the behavior of simple toys in a microgravity environment, with the results being made available to school students upon the shuttle's return.As the orbiter rolled out, the crosswind continued to push it towards the left, causing it to drift 65 feet (20 m) from the center line of the 300-foot-wide (91 m) runway.At this point, Commander Bobko began to counteract the drift by applying more pressure to the right-wheel brakes, a technique called differential steering, which brought the orbiter back to the center of the runway.