Atlantis Launches S0 Truss to Space Station

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Atlantis Launches S0 Truss to Space Station

More Information:

The space shuttle Atlantis successfully launched mission STS-110 from Kennedy Space center, pad LC39B, at 20:44 UTC on April 8. The 7-person crew is carrying the 12,122 kg (26,716 lbm) S0 truss to install on the International Space Station (ISS). The shuttle is expected to dock with the space station mid-day Wednesday, April 10. The crew is made up of Commander Michael Bloomfield, Pilot Stephen Frick, Flight Engineer Ellen Ochoa and Mission Specialists Steven Smith, Rex Walheim, Jerry Ross and Lee Morin.

Four Extra-Vehicular Activities (EVA’s) are planned for the installation of the S0 truss and Canadarm2, though only 3 are necessary. The fourth walk is for contingency, or to do additional tasks beyond the truss installation.

The US$600 million S0 truss is equipped with four computers, two laser ring gyros and GPS antennas for on-board navigation, coolant lines, electrical cabling, and complex power control and conditioning equipment. The 4.3 m (14 ft) by 13.4 m (44 ft) long truss includes more than 150 astronaut hand holds, almost 50 sockets for foot restraints, and more than 50 electronic boxes. Eventually four solar arrays will be attached to the truss, two at each end. A mobile Canadarm2 is also part of the truss structure installation.

Major components mounted on the S0 truss include:

Power distribution system to control flow of electricity from the solar arrays into the space station
DC-to-DC converter units to step down solar array voltage to levels needed by the station's internal systems
Secondary power control and switching systems
Two computers to control systems inside the S0 truss segment
Two computers to control systems in future outboard truss segments
Global Positioning System antennas and two laser ring gyros to permit on-board U.S. determination of the station's orbit and orientation for solar array and antenna aiming
A three-switch video distribution system that will route television from all externally mounted cameras, including those on the Canadarm2, into the station or down to Earth
Strain gauges, accelerometers and other instrumentation to monitor the truss structure
Instrumentation to monitor the space environment
The mobile transporter and its associated rails and subsystems

The truss has a timeline on it, a lifetime, once it is removed from the payload bay, of 16-hours, by which it must be powered. A second set of launch-to-activate (LTA) cables are available to bypass the normal way of hooking up the S0 and provides power to the critical boxes if they run behind on their timeline.

The mobile transporter is mounted on the S0, attached to a pair of rails that run the full length of the truss segment. The transporter measures 2591 by 2718 cm (102 by 107 inches), weighs 873 kg (1,923 lbm). The transporter is capable of a top speed, unloaded, of 25.4 cm (one inch) per second. When it crosses joints between truss segments, the speed will drop to a 1.524 cm (0.06 inches) per second. The transporter is equipped with four of load transfer units (LTU - claw-like devices) that lock the platform in place at various truss work sites so the Canadarm2 can maneuver large components. A roller suspension unit keeps the mobile transporter on its rails. The Canadarm2 will route data and video back to the station through a trailing umbilical system (TUS). The TUS will unroll behind the transporter as it moves forward and roll back up when it moves the other way.

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April 8, 2002