No Quick Fix
From the NYT over the weekend:
I'm certainly not in a position to judge any of this on a scientific or engineering level. But does this sort of thing give anyone the warm and fuzzies about NASA's ability to deal with the safety and quality-control problems that have resulted in two national disasters?
NASA officials confessed Friday that they were still perplexed by the fuel sensor malfunction that caused them to scrub the liftoff of the shuttle Discovery on Wednesday, and they postponed the shuttle's return to orbit until next Friday at the earliest.So let me get this straight: 1) We're not sure why there's a problem, leading to 2) We don't know how to fix it, devolving into 3) We're already back to considering suspension of safety measures.
The officials added that if they could not find the source of the problem after using every resource, they would consider flying the shuttle with the issue unresolved. But in a briefing that followed a meeting of the mission's management team, N. Wayne Hale, deputy manager of the shuttle program, said such a decision would be a last resort.
"I feel very confident that we will get a solution to our problems," Mr. Hale said.
The problem that prevented a launching on Wednesday, with the seven astronauts being strapped into their seats and the countdown clock down to 2 hours 20 minutes, was a false reading from one of four emergency cutoff sensors in the shuttle's liquid hydrogen tank.
The sensors, called ECO for short, detect levels of hydrogen. If the tank is emptying out more quickly than it should during ascent, the sensor sets off a shutdown of the engines so they do not run on empty, with potentially catastrophic consequences.
While only two sensors are needed to monitor fuel levels, a NASA rule requires that for redundancy's sake, all four be working. It is that rule the officials said they might consider suspending.
I'm certainly not in a position to judge any of this on a scientific or engineering level. But does this sort of thing give anyone the warm and fuzzies about NASA's ability to deal with the safety and quality-control problems that have resulted in two national disasters?
posted by The Cunning Realist at Sunday, July 17, 2005
19 Comments:
My favorite line comes from the movie Armageddon, when Owen Wilson's character says:
"You know we're sitting on four million pounds of fuel, one nuclear weapon and a thing that has 270,000 moving parts built by the lowest bidder. Makes you feel good, doesn't it?"
Lets hope they have fixed their technical, management, and trouble-shooting skills.
The media had early on grabbed hold of this topic and had all kinds of specials planned, but since they have had delay after delay I haven't heard much. The last I heard the launch delay was indefinite. It sounded pretty iffy, even before the sensor, when the shuttle was just sitting a couple hours from launch and a plastic cockpit window cover fell off and damaged the thermal tiles.
NASA attempts to change mind-set in wake of Columbia tragedy
They spent $857,000 to redecorate a room to "encourage" engineers to talk. This sounds like the old zero-defect quality *hit that our management was sold. Nice idea, but not if it is only lip-service from management. I hope they got more than some framed pictures on the wall for that amount of money.
One of the best articles I read about the Columbia disaster was "Columbia's Last Flight" by William Langewiesche in the Nov 2003 issue of The Atlantic Monthly. It's not online for some reason, so I quote from the copy of it I saved:
"One of the CAIB (Columbia Accident Investigation Board) investigators told me that he asked Linda Ham (head of the Mission Management Team for the flight), 'As a manager, how do you seek out dissenting opinions?'
According to him, she answered, 'Well, when I hear about them...'
He interrupted. 'Linda, by their very nature you may not hear about them.'
'Well, when somebody comes forward and tells me about them.'
'But Linda, what techniques do you use to get them?'
He told me she had no answer."
I can't tell you how many times I have used that quote...always to deafening silence.
While I'm by no means an expert I did some work on NASA contracts in the past. I imagine that so far they have tried to figure out the problem remotely, without access to the offending sensor. Identifying the sensor problem from here on would require a partial teardown of the fuel tank which would be very expensive and time consuming. It is standard procedure for a safety panel to review and grant waivers since the documented rules are made at least double redundant. In this case the sensor appears to be have 2 fail safes, and its sole function is to provide data in the event that a number of other things go wrong. It is quite reasonable that the first part of the investigation checked to see if the sensor fault was caused by something that is a threat to the rest of the vehicle, and now they are considering ignoring the sensor itself.
How old are these shuttles, anyway? They were flying when I was in grade school, a quarter century ago.
I've also done my share of work in launching rockets. Probably they have tried to isolate the fault and couldn't pinpoint it. Maybe the sensor was tested and it was good after all, then where do you go next? Like the previous poster said, maybe they have to tear out the entire tank and rebuild the sensor system. But that's very costly. Engineers always make tradeoff decisions based on the calculated risks and payoffs. In a perfect world of course they would like to fix the problem before launch, but that would mean months more of delays. On the other hand, if they have a multiple redundancy system there are still 3 sensors working, one for backup. In all likelihood that's a pretty good margin of safety, but who is going to sign off on that? Looks like it's the call of the NASA administrator at this point.
I think the public attitude towards NASA is a touch unrealistic. Spaceflight is very, very dangerous, and unavoidably risky. A better question, in my mind, is what is the purpose of this mission? As near as I can figure out, there mostly isn't any, as there is very little scientific purpose to the International Space Station this mission is supposed to support.
The Shuttle has outlived its usefulness and should be retired; whether we need a vehicle that can put 7 people in near Earth orbit, given the budget problems we have and the spectacular success of robotic spacecraft as alternatives for most manned missions, is a very much open questions. A smaller, more advanced space service vehicle may be the answer. And if we have to wait a few years for it, with no manned launches (except Russian ones, which we could always commission, thereby fostering cooperation), so be it. I say, scrap the shuttle, after one last, very risky, minimal crew mission: servicing Hubble. That's about the only useful thing the shuttle could do right now, and, ironically, it's the one thing NASA decided it didn't want to risk doing.
Check the historical record of the Apollo program, the technological wizardry, visionary thinking, risk-taking and most impressively, speed in accomplishing the mission.
Check some of the engineering accomplishments of the 1930s. Hoover Dam, Empire State Building, Golden Gate Bridge, Bay Bridge. The Pentagon was built in 18 months in the 1940s. Note how all of these marvels, built in astoundingly short time periods, have endured. These come to mind because I live in the SF Bay Area. I recall the October 1989 earthquake and how the Bay Bridge suffered. According to various and sundry experts, the collapse of one segment—subsequently repaired—necessitated a new bridge built to modern seismic standards. Today, almost 16 years later, they're still squabbling about the new bridge, wasting money merrily as they go along. Now we hear the new bridge will be completed in 2011, a mere 22 years after the need for it was perceived. Of course it will cost three times the original estimates.
Our modern society has become too complex and, in particular, too risk-averse. The old NASA guys would have unhesitatingly done an expert risk assessment, bitten the bullet and gone with this launch. Now, due to unrelenting media focus and the whiners and weepers endemic to our society, NASA is paralyzed. Don't forget politics, either. Those boys at NASA know that most shuttle missions are purely "oh, boy, look at us, we drive a bus into space" stunts and they are accordingly reluctant to take any risks. I wouldn't want to be the PM who says, "let's light this candle," when I know that "rocket scientists all the way from upper NASA management to the White House stand ready to skewer me if something goes wrong.
The astronauts are different now, too: we've gone from the old military jocks to whom risks were a normal part of life to a new breed that includes school teachers, pure scientists, politicians, etc.
Shit, here we are 36 years later, and we can't even get back to the moon. And the chief rocket scientist in the White House wants to go to Mars. Right.
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