Endeavour’s Final Launch further delayed another Week or more

by Ken Kremer on May 1, 2011

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Space Shuttle Endeavour awaits launch sometime in May from Pad 39 A following launch scrub called on April 29, 2011. Critical APU heaters failed during the final countdown. The APU's are located the aft section of the orbiter around the main engines in this close up view taken while I was standing next to the orbiter in March. Endeavour and her 6 man crew will deliver the $2 Billion Alpha Magnetic Spectrometer to the International Space Station which seeks to unveil the Unknown and uncover the birth of the Universe. Credit: Ken Kremer
Update: photo below shows location of access door used to enter orbiter near the main engines

KENNEDY SPACE CENTER – The final launch of shuttle Endeavour will be further delayed, perhaps by a week or more – to May 6 or 11 time frame – as technicians working at the pad seek to determine the cause of the failure of multiple heaters in auxiliary power unit-1 (APU) which caused the scrub of Endeavour’s launch attempt on Friday, with just 4 hours remaining in the countdown. The six man crew of Endeavour had just departed for the launch pad inside the Astrovan and was forced to turn around soon thereafter. We saw them pass us by, heading back to crew quarters to await a resolution of the issues.

The launch delay came as a huge disappointment to NASA and the enormous crowd estimated at 750.000 people who came to Florida to watch the momentous liftoff in person for what many call a “life changing experience”. Even President Obama and the entire first family were on hand to witness Endeavour’s launch. But the top priority is to launch the shuttle safely and the launch team emphasized that they made absolutely no changes to the countdown procedures.

Repairs to Space Shuttle Endeavour are in progress at the launch pad. Arrow shows location of access door used by technicians to swap out the faulty Aft Load Control Assembly (ALCA-2) near the main engines. Credit: Ken Kremer

On Saturday, technicians gained access to Endeavour’s aft fuselage which houses the components suspected to have malfunction and found that the cockpit control fuse panel is working. They also verified that thermostats associated with the failed APU heaters are still not working. This indicates that the root cause of the malfunction lies deeper inside the orbiter and it will take longer for technicians to access and fix whatever is causing the problem.

APU-1 is located on the left side of the orbiter in the aft section behind the end of the payload bay.

The heaters play a critical role in keeping the APU hydrazine fuel from freezing in orbit and remain in a fluid state. If the hydrazine were to freeze and then thaw back to a liquid, it would expand and potentially rupture the fuel lines with devastating consequences.

Diagram shows location of all 3 Shuttle APU's. Credit: NASA

The orbiter has three APU’s. Only one is required to fly safely. Three units provide redundancy and all must be in working order before launch. Otherwise the launch commit criteria would be violated, forcing a launch scrub. The APUs provide the hydraulics to maneuver the main engine nozzles, elevons, rudder, body flap, landing gear brakes and nose wheel steering system.

Technical teams got to work inside the orbiter on Saturday after the rotating service structure was rolled back around the orbiter to enable access. If the problem is deeper within the orbiter at the Load Control Assembly it will take several additional days to fix the problem. Retesting of any new components inside the LCA will take at least 48 hours. Furthermore if any ordnance needs to be disconnected, a further delay of multiple additional days is inevitable.

In order to launch Endeavour on Monday, May 2, at 2:34 p.m. EDT, NASA must resume the countdown on Sunday afternoon. NASA only has until May 4 to get Endeavour off the ground until they would be forced to stand down to make way for the May 6 blastoff of an Atlas V rocket carrying an Air Force early-warning missile detection satellite.

NASA officials are in touch with Air Force officials to determine if the Air Force could be flexible in changing their launch date in the event that Endeavour would be ready to launch on the blackout dates of May 5 to 7.

NASA will hold a news briefing at 2 p.m. on Sunday to update reporters on the situation.

Read my related stories about the STS-134 mission here:
On the Cusp of Endeavour’s Final Flight
Brush Fires Erupt at Kennedy Space Center during Endeavour’s Last Countdown
Commander Mark Kelly and STS-134 Crew Arrive at Kennedy for Endeavour’s Final Flight
President Obama to Attend Endeavour’s Last Launch on April 29
Shuttle Endeavour Photo Special: On Top of Pad 39A for Final Flight
Endeavour Mated to Rockets for Last Flight Photo Album
Endeavour Rolls to Vehicle Assembly Building for Final Flight

About 

Dr. Ken Kremer is a speaker, scientist, freelance science journalist (Princeton, NJ) and photographer whose articles, space exploration images and Mars mosaics have appeared in magazines, books, websites and calanders including Astronomy Picture of the Day, NBC, BBC, SPACE.com, Spaceflight Now and the covers of Aviation Week & Space Technology, Spaceflight and the Explorers Club magazines. Ken has presented at numerous educational institutions, civic & religious organizations, museums and astronomy clubs. Ken has reported first hand from the Kennedy Space Center, Cape Canaveral and NASA Wallops on over 40 launches including 8 shuttle launches. He lectures on both Human and Robotic spaceflight - www.kenkremer.com

allstar May 1, 2011 at 2:08 PM

Sometimes, just sometimes, I just wonder if all these malfunctions with the shuttles are the NASA people trying to drag out the shuttle missions for as long as possible..

r136 May 1, 2011 at 2:32 PM

Right, because that’s logical.

Ken Kremer May 1, 2011 at 3:33 PM

thats ridiculous

CrazyEddieBlogger May 1, 2011 at 9:55 PM

A good natured jab:
Napoleon Bonaparte Quote:
“Never ascribe to malice that which is adequately explained by incompetence…”

Jon Hanford May 2, 2011 at 5:24 PM

It’s the *curse* of the AMS! :D

More seriously, the saga of Sam Ting’s AMS-02 instrument is comparable to the ups and downs of Japan’s (ultimately successful) Hayabusa mission. For those not familiar with the story this wiki entry describes some of the tribulations of the AMS-02: http://en.wikipedia.org/wiki/Alpha_Magnetic_Spectrometer#Launch_cancellation_and_restoration

[Here's hoping that AMS-02 & Endeavour see orbit by months end]

Paul Eaton-Jones May 3, 2011 at 11:51 AM

Will someone PLEASE switch this bloody craft’s life-support machine OFF!!

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