Tuesday, July 26, 2005
(Click title to read article)
NASA is considering waiving one of the flight rules required for a shuttle launch. The rule governs low-fuel sensors for the main engine. One of these sensors failed during a pre-flight test, resulting in the current countdown delay.
NASA flight rules currently require all four sensors to be working before liftoff, but Stilson said that rule was implemented before shuttle modifications were made to improve the sensors' power systems.
An interesting comment from Discovery vehicle Manager Stephanie Stilson...
"In reality, we probably should have looked at (changing the flight rule) when we made the modification."
It appears that Ms. Stilson is saying that because the sensors are more reliable and safe, they don't need all of them working for launch. I find this a rather ominous attitude from a member of the organization whose ideas on "reliability and safety" were responsible for the deaths of 7 astronauts.
After Challenger...and Columbia...I naively thought NASA would accept and hold to the recommendations of the review board. It does not appear to be so.
Presently, if two of these low-fuel sensors fail, the shuttle's main engine will begin an emergency shutdown. What this means is that if the previously flawed sensor were to report an erroneous low-fuel condition, only ONE additional sensor would need to fail similarly for the engine to shutdown...a catastrophe during shuttle launch. Yet Ms. Stilson feels that with improved power, the rule that ALL sensors should be working is...what...too strict? I mean, there are only lives at stake.
If you only have four, and one is definitely flaky, the odds that the others will all perform flawlessly represent a gamble that NASA is apparently willing to take.
I'm glad the shuttle program is in its "last throes". We seem neither to be able to build them perfectly, nor to understand that we can't build them perfectly.
Godspeed Discovery. Hurry home.
(via Yahoo News)