With its days flying alone in orbit coming to an end, the Zvezda service module nears completion of systems checkouts in preparation for docking to the International Space Station. The linkup remains scheduled for 8:53 p.m. Eastern Time next Tuesday, July 25, as the two spacecraft fly high above the Russian Federation within the coverage area of ground communication stations.
Another in a series of rendezvous maneuvers was completed late Wednesday when Russian flight controllers sent commands to Zvezda's computers to fire its engines for 15 seconds, raising the perigee, or low end of its orbit, by 13 miles (21 kilometers). The correction burn occurred at 10:47 p.m. EDT Wednesday and changed the velocity by 10 miles per hour (4.4 meters per second), placing the service module in a 224 by 180 mile orbit (361 by 290 km).
The next two rendezvous burns for Zvezda are scheduled tonight about 30 minutes apart at 9:22 and 9:54 p.m. Eastern. The first will raise both sides of the orbit to 234 by 185 miles and the second will raise the low end by another 23 miles, to 208 statute miles.
Also tonight a docking test will be performed that includes conducting a mechanical capture test of Zvezda's docking mechanism. This test will verify the operation of the software and mechanical systems associated with docking. It also will include positioning the module in the proper docking position with the solar arrays positioned parallel to the module. This position minimizes perturbations to the arrays at the time of docking.
At present, one additional Zvezda orbit correction burn is scheduled for Sunday evening, Eastern Time. After that, the rendezvous is managed by the Zarya control module, which becomes the active vehicle, performing up to three rendezvous and correction maneuvers en route to the final approach and docking Tuesday night.
Yesterday, controllers tested the camera on Zvezda that will view the ISS on approach. They also reviewed telemetry data from Zvezda's five batteries. Each battery captures energy from the module's solar arrays for use by onboard electronic equipment.
As of Noon EDT Friday, Zvezda had completed 151 orbits of the Earth since its launch from the Baikonur Cosmodrome July 12. The next Mission Control Center status report will be issued Monday, July 24. For more information, call the Johnson Space Center Newsroom at 281/483-5111.
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