Skip to comments.NASA Moon Rocket May Shake Too Much (Pogo Problem)
Posted on 01/19/2008 11:03:55 PM PST by anymouse
NASA is wrestling with a potentially dangerous problem in a spacecraft, this time in a moon rocket that hasn't even been built yet.
Engineers are concerned that the new rocket meant to replace the space shuttle and send astronauts on their way to the moon could shake violently during the first few minutes of flight, possibly destroying the entire vehicle.
"They know it's a real problem," said Carnegie Mellon University engineering professor Paul Fischbeck, who has consulted on risk issues with NASA in the past. "This thing is going to shake apart the whole structure, and they've got to solve it."
If not corrected, the shaking would arise from the powerful first stage of the Ares I rocket, which will lift the Orion crew capsule into orbit.
NASA officials hope to have a plan for fixing the design as early as March, and they do not expect it to delay the goal of returning astronauts to the moon by 2020.
"I hope no one was so ill-informed as to believe that we would be able to develop a system to replace the shuttle without facing any challenges in doing so," NASA administrator Michael Griffin said in a statement to The Associated Press. "NASA has an excellent track record of resolving technical challenges. We're confident we'll solve this one as well."
Professor Jorge Arenas of the Institute of Acoustics in Valdivia, Chile, acknowledged that the problem was serious but said: "NASA has developed one of the safest and risk-controlled space programs in engineering history."
The space agency has been working on a plan to return to the moon, at a cost of more than $100 billion, since 2005. It involves two different rockets: Ares I, which would carry the astronauts into space, and an unmanned heavy-lift cargo ship, Ares V.
The concern isn't the shaking on the first stage, but how it affects everything that sits on top: the Orion crew capsule, instrument unit, and a booster.
That first stage is composed of five segments derived from the solid rocket boosters that NASA uses to launch the shuttle and would be built by ATK Launch Systems of Brigham City, Utah.
The shaking problem, which is common to solid rocket boosters, involves pulses of added acceleration caused by gas vortices in the rocket similar to the wake that develops behind a fast-moving boat, said Arenas, who has researched vibration and space-launch issues.
Those vortices happen to match the natural vibrating frequencies of the motor's combustion chamber, and the combination causes the shaking.
Senior managers were told of the findings last fall, but NASA did not talk about them publicly until the AP filed a Freedom of Information Act request earlier this month and the watchdog Web site Nasawatch.com submitted detailed engineering-oriented questions.
The response to those questions, given to both Nasawatch and AP, were shared with outside experts, who judged it a serious problem.
NASA engineers characterized the shaking as being in what the agency considers the "red zone" of risk, ranking a five on a 1-to-5 scale of severity.
"It's highly likely to happen and if it does, it's a disaster," said Fischbeck, an expert in engineering risks.
The first launch of astronauts aboard Ares I and Orion is set for March 2015.
On the Net:
NASA's Ares and Orion program:
shake rattle and roll
Major redesign required here.
The way I read this is that they are in the process of design and there is no need to redesign something that has not yet had a final design to redesign......or whatever...
Is it the UN space treaty that holds us back?
Modulating flux capacitor......?
I’m not sure if they were testing some J-2 variant at Stennis this past week, but it was definitely making my house shake. A little unusual in that you typically hear the engine testing, but you don’t feel it.
If anyone can figure this out it is NASA.
I hope the last few decades of budget cuts and inattention from the public have not reduced the brain power of one of our most capable agencies.
i’m no space geek but if they could send one up no worries in the 60s why not now?
Now is the time to find these problems.
In the engineering stage.
“Modulating flux capacitor......?”
Simple! Reverse the polarity.
A crack in the dilithium crystals?
“im no space geek but if they could send one up no worries in the 60s why not now?”
I’ll answer that question by saying “Good enough for government work.” In other words, completely unacceptable by non-government standards. NASA has become a monstrous, inefficient beaurocracy. Things crash, break, fall apart, fail to operate, because these morons can’t even read the designs. When something’s supposed to have an auto-guidance using the metric system, and your department programs it to use feet, and no one notices... That’s a SERIOUS PROBLEM!
There are firms that would LOVE to get a contract to build a shuttle, or a space station, or get a man on the moon again. Why won’t we let them try?
I a so old that I know they used to something called a Slide Ruler and then actually build the thing.
And it worked!
Put men on the moon six times and can’t make a vehicle to get us there again? Lends credence to the original hoax.
Of course the simulator had been under development for many years prior to the shuttle's first launch. During that development it was noticed that the "motion base" simulator would experience significant vibrations during the roll maneuver that was part of lift off.
It was presumed that the source of the vibration was an elusive software bug. After many months of fruitless debugging NASA finally took the (rare) step of putting a cash bounty out on the squashing of this particular bug.
Nevertheless, no bug was ever found and launch day approached. When the launch finally did take place, and the roll maneuver was executed for the first time, the astronauts were astonished to experience the very same vibration.
For us nerds that was a pretty neat story.
LESSON LEARNED: Pay attention to your simulatons.
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