English: A replacement gyro destined for the International Space Station has arrived at the Kennedy Space Center. The new CMG -- or Control Moment Gyro -- is undergoing testing. The testing is a general health check to prepare it for launch aboard the Space Shuttle. Testing will insure that the gyro is in good working order before leaving Earth. The gyro replacement on the ISS requires a spacewalk to remove the malfunctioning CMG and to install the new one. This will restore the ISS to four fully functioning CMGs, which are critical to the operation explains Kennedy Space Center's Lead Avionics Engineer Dean Orr. 'The Control Moment Gyroscope is very critical to the Station because it maintains the smooth attitude control of the Station, which is control of the Station and steering on the roll, pitch and yaw axes of the Station. The Control Moment Gyroscopes also maintain the microgravity environment. They maintain a smooth environment for the scientific experiments on board the Space Station.' When the current testing is complete, the Control Moment Gyro will be ready for pre-launch processing.