Shuttle Launch Scrubbed | Junior Flyer | Aviation Fun and Education

# Shuttle Launch Scrubbed

Posted By Thursten Master on Apr 29, 2011 | 0 comments

NASA cancelled the planned launch of Shuttle Endeavour, stopping the countdown at T minus three hours. A delay of at least three days is expected to allow trouble shooting of the vehicle’s troublesome Auxiliary Power Unit (APU).

The technical details are explained by NASA as follows:

> During today’s countdown, engineers detected a failure in one of two heater circuits associated with Auxiliary Power Unit (APU) 1. Heaters are required to keep the APUs’ hydrazine from freezing on orbit. 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.

> Endeavour’s external tank will be drained, technicians will enter Endeavour’s aft compartment overnight and by tomorrow afternoon, will put in a platform to gain access to the avionics bay where the Load Control Assembly is located. Once there, they will assess whether they need to remove and replace the switchbox, or fix an electrical wiring short.

> Because of this, Leinbach said there will be a minimum 72-hour scrub turnaround.

We hope that after the Shuttle is scrubbed it will be clean enough for a launch early next week!

Author: Thursten Master

Thursten, or "Thrust" as he prefers to be called, is our resident technical genius. This is not a term used lightly... he really does have a brain the size of a planet and he solves a myriad of tricky problems for us. Thrust is particularly interested in the science of flight and, unlike many large-brain academics, is very good at explaining science in terms that normal people can understand.

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