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:
http://www.nasa.gov/mission_pages/constellation/ares/index.html
This thing is going to shake apart .....we’ve got to fix it...
Capt. Obvious call your office.
Pogo Problem?
“We are confronted with insurmountable opportunities”
or
“We have met the enemy, and he is us”?
The federal government has become a place where young people go after college to retire to the “good” life while they are in their early 20s. The only thing they know how to do well is get the check deposited and party. Meanwhile, those who are capable are shown the door because they may do something to end the gray train.
Cut the government in half and you would still have enough inefficiency to half it again.
The problem is those solid rocket boosters. They were already controversial as part of the shuttle launch system, one of the original corner-cutting schemes. They are more powerful than liquid fuel rockets, but harder to control and cannot be shut off mid flight. The Challenger disaster showed how unreliable they can be. The Saturn V first stage worked just fine during the 60’s and 70’s, was in fact very reliable and efficient. NASA has probably invested too much in solid rocket fuel tech to just drop them now.
The Saturn V Moon Rocket was a multistage liquid-fuel rocket which was a concept developed by Wernher von Braun and a team of German scientists.
The Challenger disaster showed how unreliable they can be
Most equipment is unreliable when you use it outside it’s design parameters.
Yes, but I don’t think liquid fuel rockets even need O ring seals. It’s just one more thing that can go wrong due to the complex requirements of controlling a solid fuel reaction.
Most likely it's because of the difference of mass between the Shuttle and the Ares. More mass makes pogo less of a problem.
These types of problems are going to pop up with any new program, and the media is going to blow it out of proportion.
Don't cross the streams.
It would be bad.
Scrap the manned programs and send out robots.
They could do 100X the exploration at a tenth the cost.
We should be drilling Jupiters moon’s, more landings on Titan, not flying around in cirles in low-earth orbit tin cans anyway.
Really, there’s nothing in this system worth walking around on right now, and dat’s da name of dat tune.
Athough terraforming Mars for eventual habitation in another 200 years or so has it’s charms....so get chopping there too.
“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.”
This is a result of using solid fuel boosters. Why are is NASA using them rather than safer, less expensive, and less polluting liquid fueled boosters? Those seemed to work fine in the Apollo project.
Fortunately, private enterprise may yet come to the rescue, in the form of the SPACEX Falcon 9 project and its kerosene fueled liquid engines.
Truly sad....
The Old Guard (personified by Chris Craft, Gene Krantz, and John Aaron) were not afraid to take risks and do seat of the pants engineering.
Today's NASA is just a bloated bureaucracy that is risk advsere to anything...
Liquid fuel doen’t pack the punch of solid fuel, and it’s harder to store. High thrust-to-weight is especially important during liftoff. NASA has also designed them to be recoverable. The trade-off is not being sure what the damn things will do once the fuse is lit.
You know, I've always wondered why they don't cast the solid fuel rocket in one piece instead of in segments, thus eliminating the problematic O-rings. It must be a transportation issue.
I'm not so sure about that. I'm just about done reading a book by a first generation mission specialist.
His big disappointment, in addition to losing classmates on the Challenger, was that it killed shuttle launches from VAB.
The USAF wasn't keen on the shuttle launching satellites to begin with, and the SRBs for use at VAB were designed with a composite material, and if Thiokol couldn't get it right with metal....
(VAB launches would be for polar orbits. More energy is required since launches wouldn't benefit from Earth's Eastward rotation, hence the need for greater thrust to weight. From an astronaut POV, a polar orbit allows viewing of the entire planet, not just an equatorial oscillation.)
Bottom line is that planned shuttle launches from VAB were canceled after Challenger, along with the composite SRBs.
Some poster once said that Thiokol got the contract over a Georgia-based firm because of Sen. Jack Garn, of Utah.
The Georgia firm pitched a solid SRB, not a sectional one. While I'm sure Thiokol could make it a single piece, getting it to KSC was the problem. The geography favored the GA firm. Garn's influence favored Thiokol.
If it wasn’t a reusable design they could probably make it all one piece, but having to refuel and overhaul it every time, doing in sections makes it easier I would guess.
If it wasn’t a reusable design they could probably make it all one piece, but having to refuel and overhaul it every time, doing in sections makes it easier I would guess.
Quick, import some Germans!
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