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More Details for 1999-11-18

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Flight controllers in Moscow and Houston began the second round of deep-cycling of the batteries inside the Zarya module last weekend, but stopped the procedure when the first battery did not discharge properly. The deep cycling of the batteries is done about every six months to maintain the units efficiency and lifetime to provide the maximum electrical capability to station systems.

Battery number two completed a discharge-charge cycle, but failed to discharge on the second cycle. At that point, controllers removed it from the electrical bus. The four usable batteries are easily handling all electrical needs of the station and no power problems are foreseen since the complex can operate on as few as three batteries.

While this in no way hampers station operations, some heaters on the Unity module were powered off to minimize power consumption. The station currently is in near full sunlight as it moves around the Earth, so no power problems or temperature issues are foreseen. Troubleshooting on the battery two system - comprised of the battery and its associated electronics - is underway and no conclusion has been made as to what caused it not to discharge properly.

Battery three was cycled yesterday with no issues. Evaluation and analysis will be conducted during the next day or so before a decision will be made regarding resumption of cycling of batteries four, five and six. During the present battery cycling, Unity's early communications system is being used to supplement Russian ground station commanding to Zarya's batteries and other systems.

Meanwhile, ISS managers are reviewing details of a reboost plan for the ISS. The reboost, scheduled for December 1, will raise the complex's orbit to eventually place it at the proper altitude for rendezvous with the Zvezda service module scheduled to launch to the ISS early next year.

All other station systems are in excellent shape as it orbits at an altitude of 239 by 225 statute miles. Since the launch of Zarya last November, the ISS has completed more than 5,686 orbits. S