The launch of space shuttle Endeavour has been delayed at least until Monday due to a failed heater circuit in one of the orbiter's three Auxiliary Power Units. Launch director Mike Leinbach says there'll be a 72-hour "scrub turnaround" while engineers assess and try to correct the problem. The next attempt to launch STS-134 will come no earlier than Monday at 2:33 p.m. EDT.
The three APUs provide hydraulic power to steer the shuttle's aerosurfaces during ascent and entry. Heaters are required to keep the APUs' hydrazine from freezing on orbit. During today's countdown, attempts to activate the heater were not successful and engineers now believe the problem might be associated with a Load Control Assembly, which is a switchbox, located in the aft end of Endeavour, or an electrical short in the wires leading into or out of the switchbox.
The three APUs provide hydraulic power to steer the shuttle's aerosurfaces during ascent and entry. Heaters are required to keep the APUs' hydrazine from freezing on orbit. During today's countdown, attempts to activate the heater were not successful and engineers now believe the problem might be associated with a Load Control Assembly, which is a switchbox, located in the aft end of Endeavour, or an electrical short in the wires leading into or out of the switchbox.
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