Posted on 07/24/2005 2:25:59 PM PDT by Thinkin' Gal
Space shuttle Discovery's flag waves in the breeze as Discovery
sits on the pad covered by the rotating service structure at
Kennedy Space Center in Cape Canaveral, Fla. Sunday,
July 24, 2005. The countdown is under way for a Tuesday
morning launch.(AP Photo/Terry Renna)
By MARCIA DUNN, AP Aerospace Writer
CAPE CANAVERAL, Fla. - Shuttle managers debated Sunday about what to do — halt the countdown or fly — if a fuel gauge problem resurfaces right before the second launch attempt for NASA's oft-delayed return to space.
Discovery is set to lift off Tuesday at 10:39 a.m., the same time Columbia took off on its doomed mission in 2003. Forecasters put the odds of good launch weather at 60 percent, with rain and clouds as the main concerns.
"We have had a great many challenges preparing the space shuttle Discovery and her crew to get ready for this historic return-to-flight mission. Certainly, that's the cost of creating the safest shuttle to date," said NASA test director Jeff Spaulding.
The latest challenge involves the hydrogen fuel gauges in Discovery's giant external tank.
Mission managers had yet to settle on a strategy for how best to manage the fuel gauges, which forced a launch delay the first time around. One option would be to proceed with liftoff if just three of the four gauges work, which would mean bending a launch rule that was implemented in the wake of the 1986 Challenger disaster.
A decision on whether to relax the rule for this first space shuttle flight in 2 1/2 years was expected by Sunday evening.
Despite exhaustive effort, NASA still does not know exactly why one of the fuel gauges in Discovery's external tank failed a prelaunch test on July 13.
Workers last week repaired faulty electrical grounding inside Discovery in hopes that would solve the problem, and swapped the wiring between the troublesome fuel sensor and another one to better understand the issue if it reappears.
The same type of problem occurred back in April during a fueling test, and was written off then as an "unexplained anomaly."
The fuel gauges are needed to prevent the main engines from shutting down too soon or too late during liftoff. The first scenario could result in a risky, never-attempted emergency landing; the second could cause the engine turbines to rupture and, quite possibly, destroy the spacecraft.
Only two fuel gauges are needed to avoid such dangerous situations, but NASA requires all four to be working at liftoff for redundancy.
NASA has just one week to launch Discovery and its crew of seven to the international space station, before putting off the mission until September.
The space agency is insisting on good lighting in order to see any signs of the type of launch damage that crippled Columbia.
The opportunity for good photography, both at Cape Canaveral and over the North Atlantic when the fuel tank separates nearly nine minutes after liftoff, diminishes in August and is unacceptable until Sept. 9.
Columbia and its seven astronauts were brought down by a broken section of fuel-tank foam insulation that struck just over a minute after liftoff and proved lethal during descent two weeks later, on Feb. 1, 2003.
(10/15/05) After three months of deliberation, NASA has decided to continue to delay the launch of the space shuttle Discovery and to hold out for more money from congress.
They're worried that a faulty sensor will shut down the SSME's prematurely, causing a catastrophe.
I'm no rocket scientist, nor do I play one on TV, but why couldn't they write it into the software to ignore these sensors until XX seconds into the flight when they know the fuel will still be there?
I'm sure it's more complicated than that, but that's my $.02
This is pathetic. Can NASA not keep these things working? Yes, I know, the Shuttle was never great in the first place, and it's an amazingly complex machine. But I really have doubts about the future of space travel if minor problems like these delay launches for weeks. And let's not get into the ability of rain showers to completely kill a launch...
"NASA Debates What to Do if Problem Returns "
Stick a fork in it.
Unless they know exactly why the gauge malfunctioned I fail to see how they can justify the launch.
Somehow, I doubt this would be any help to NASA ;>)
Well, there are at least two complications with that:
1. Quick software work-arounds often introduce unintended consequences or bugs of their own. The cure can often be worse than the disease.
2. A faulty reading on a sensor may actually be a symptom of deeper problems. Even if you work around the one bad reading, you may just be masking the real problem, which can bite you on the butt if you go ahead and launch. Better to make sure you've rooted out and fixed the real problem, *all* of it, instead of just slapping on a software patch and launching while something -- you're not entirely sure what -- is still wrong.
"NASA Debates What to Do if Problem Returns"
Delay the launch until the problem if fixed, and until you're absolutely certain the shuttle is in perfect working condition. See even a dope like me can figure that one out.
NASA is now saying that it will launch even if Discovery is plagued by the same fuel gauge problem that halted the previous countdown two weeks ago.
Discovery is set to lift off Tuesday at 10:39 a.m.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.