The activation of the station's Ku-Band antenna remains on hold until a software update is uplinked to the station's computers Thursday. This command is designed to correct an apparent pointing error with the dish-shaped antenna. The Ku-Band system is used to transmit television, voice and high-speed data to the ground. Normal communication is being managed through the S-Band audio system. Any required TV images, in the meantime, can be accommodated through the use of the laptop computer-based digital video system.
Also, the crew changed out components of the carbon dioxide removal assembly system in the Destiny Laboratory in an effort to recover its use. Troubleshooting work continues as engineers evaluate what appears to be a sluggish vent valve on the unit. The Zvezda module's CO2 removal system is working fine and providing more than adequate capability to cleanse the cabin air in the meantime.
Oxygen for the crew currently is being provided by supply tanks in the Progress supply vehicle, which boosted the cabin air yesterday. Without the Progress, the Russian Elektron in Zvezda provides oxygen generation. Not presently needed, the Elektron is turned off.
Apart from maintenance tasks and routine housekeeping chores, the crew has been working with experiments on board. The Human Research Facility rack in Destiny is managed and operated by a science and operations team from the Telescience Support Center down the hall from the station's flight control room in Mission Control, Houston. All payloads on the station are overseen from NASA's Marshall Space Flight Center in Huntsville, Alabama where the Payloads Operations Center is located.
The Progress supply craft currently docked to the aft end of the Zvezda module is scheduled to be undocked around April 15 in preparation for the arrival of the next shuttle flight carrying the station's Canadian-built robot arm and a second Italian Space Agency supplied logistics module called Raffaello. The open port allows for the relocation of the Soyuz capsule around April 17, which will provide clearance for the placement of Raffaello during the docked phase of the shuttle mission. The Flight Readiness Review to evaluate the readiness of Endeavour, its crew and the station for the shuttle's launch on the STS-100 mission will be held Thursday to select a target launch date, which currently is around April 19.
Earlier today, a small test firing of the Progress supply ship's thrusters was performed to verify command capability of the steering jets via the Zvezda module's computers. The brief engine burn resulted in a change in the velocity of the Station of only one meter per second. It was the first time the Progress thrusters were commanded from the ground through the Zvezda module's computers.
The test sets the stage for another Progress engine firing early next week designed to refine the orbit of the station relative to the Baikonur Cosmodrome in Kazakhstan in preparation for the arrival of a new Soyuz capsule to replace the one presently docked to the station. Soyuz capsules routinely are changed about every 180 days. A taxi crew, as it's called, will deliver the new capsule and return to Earth in the one launched last October carrying the station's first Expedition Crew.
Late Tuesday, a handover of the station's attitude control from the electrically driven Control Moment Gyroscopes to the Zvezda module's thrusters was performed as a test to verify that the automatic switchover would occur in the event that the CMGs developed a problem. The test allowed the system to 'think' that the gyros had failed down to one operational system and the computers automatically switched to the thrusters. The test verified the system is fully operational.
The International Space Station continues to orbit the Earth in good shape at an altitude of 238 statute miles (384 km).