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The Zvezda service module is operating in excellent shape as it phases toward the International Space Station with docking still scheduled for 8:46 p.m. on July 25. Over the weekend, Russian flight controllers here in the Mission Control Center outside Moscow, completed checking out the 'Regul' telemetry system, which involved cycling through various software modes to ensure good command links from the ground, and analyzing the return link from the module. With the module operating flawlessly, no activity was performed Sunday, which was the first of three days set aside for troubleshooting, if required. Earlier today, controllers tested the module's motion control and navigation system using onboard sun sensors. Last week the system was tested using the star sensors. These tests verified the full operation of the onboard software to manage Zvezda's guidance system. Also today, routine cycling of the five batteries began. The module was launched with five of eight batteries installed. The remaining three will be delivered and installed during the next Space Shuttle visit scheduled for September. Later today, Zvezda’s black-and-white docking camera will be turned on to verify its operation in anticipation of the docking next week. That camera will provide flight controllers with the first view of the International Space Station as it approaches. The images will complement the accompanying rendezvous data. Meanwhile, the ISS is continuing to operate in excellent shape also, awaiting the arrival of its newest module. Late tonight, a docking test will be performed that actually mimics the final two orbits of the automatic rendezvous and docking. As part of the test, the Zarya control module’s thrusters will be fired briefly twice (about 1 meter per second) to correct the phase angle between the two spacecraft. This minor update to the rendezvous plan is necessary because controllers determined that the reboost engines on Zvezda were a little more efficient than predicted. The next scheduled rendezvous maneuver by Zvezda is scheduled for Thursday. Late last week, Zarya’s propellant system was reconfigured so that fuel from the storage tanks can be utilized for the rendezvous. This unique ability by the attitude control thrusters to use propellant from the storage tanks in addition to the propellant tanks, protects for a complete rendezvous with no further reconfiguration activity required. As of 11 a.m. CDT Monday, Zvezda had completed 88 orbits of the Earth. Its present altitude is 200 miles, or 323 kilometers. The next Mission Control Center status report will be issued Wednesday, July 19. For more information, call the Johnson Space Center Newsroom at 281/483-5111. -END-
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