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Of tanks, foam and culture
I read the articles above. Discounting the range safety one as it was pre
Columbia, and I think, a different issue, I do feel that the one question which is never going to be answered is,'how much foam can you lose'. Seems to me that if you want to be brutally honest, there is a design flaw, and all you can do is patch it up so that minimal size of the shed areas is below catastrophic damage constraints. However, nobody really knows what these parameters are. The problem is that early in the program, the culture was far worse than now, in that they flew it without detailed knowledge of what a big hit might do, and they got away with it more than perhaps they had a right to. Now however, you have on the one hand a commitment to finish the job of building the space station, competition for funds, an aging vehicle and a sudden awareness that you have an insurmountable problem. If you then have people willing to fly it and everyone breathing down your neck, what do you do? Has anyone ... A: found out what settlement you could get with the international partners if you said you could not fulfil your part of the deal? B: thought about seeing if any of the equipment could be flown on conventional rockets? Talked to the partners about some form of compromise where the US would pay dev. costs for them to build a launcher to carry the parts to orbit. Seems to me that the ISS is a white elephant itself, and maybe a smaller system perhaps several, might be a better answer. Brian -- From my IMAP account Brian Gaff |
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Of tanks, foam and culture
Why has the foam loss got worse after 2 years and billions of dollars
spent to fix it? from florida todays space blog: First RTF flight took more foam hits Discovery endured more foam debris hits than average on the first post-Columbia mission. The damage sites were not as deep, but the number (176) is above the average (144) over the 25-year life of the shuttle program. That's one of several data points in a report in this morning's Florida Today regarding the decision to launch last year's return to flight mission and the parallels to decisions being made in the runup to the next flight this summer. You can read the foam story here and a summary of what other independent reviewers have said on these issues here. For those who like to read detailed documentation, the stories include links to some of the studies and reports that we reviewed. Most are previously-released documents made public in the nine months since the accident. One not available anywhere else yet is the final post-flight inspection, which some call the "ding report." Check it out here. The other documents can be downloaded from links in the stories noted above. posted by John Kelly Then we have the publics perception of the money pit err station: Space station too weighty for NASA? By Howard Witt Tribune senior correspondent Published March 27, 2006 HOUSTON -- This Wednesday evening, if all goes according to plan, an American astronaut and a Russian cosmonaut will blast off aboard a Russian rocket headed for the International Space Station, the latest crew in an uninterrupted procession that has kept humans aboard the station for more than five years. And if all goes according to routine, outside of the professional space community and a handful of space enthusiasts, few Americans are likely to even notice. The workaday space station, far less dramatic than a space shuttle mission and far less compelling than planned journeys to the moon and Mars, long ago ceased to command much public fascination. But the half-built space station continues to command a large chunk of NASA's operating budget, even as President Bush and Congress have directed the space agency to shift its focus to a return to the moon by 2020 and a journey to Mars after that. Now, to help cover the cost of completing the orbiting outpost that is supposed to serve as a unique platform for scientific research, NASA is slashing its science budget by $3.1 billion. In a decision that some critics liken to the space agency eating its young, NASA announced last month it was canceling numerous experiments that were planned aboard the station to help future astronauts survive long-duration missions to the moon and Mars. Several robotic probe missions to distant planets also were scrapped, as well as funding for hundreds of space researchers at universities across the country. "The space station was sold to Congress for decades as a lab to do this kind of broad-based research," said Keith Cowing, a former NASA engineer and editor of nasawatch.com, a Web site often critical of the space agency. "Now they've started gutting the station just when it is at the point of being able to do all the things it was supposed to do. That leaves the purpose of the space station as something for astronauts to fix." NASA administrator Michael Griffin said earlier this month that he regretted having to cut the agency's budget for scientific research, but that he was left no choice by the combined costs of 16 more shuttle missions to complete the space station by 2010 while simultaneously beginning design and construction of next-generation rockets and vehicles to take astronauts to the moon and Mars. "We focused on redefining the station assembly sequence in fact to concentrate on assembly, and we are largely deferring utilization and we are paring logistics to the bone," Griffin told reporters at the Kennedy Space Center in Florida. "We don't like that, but confronted with a choice between having a high confidence to be able to complete the assembly of the station and deferring utilization, or utilizing it heavily as we built it and possibly not finishing, we chose the former course." Falling short of promises Some scientists contend that cutting NASA's research grants will drive experts out of the space field and cause long-term damage. "Fifteen or 20 years from now, NASA will have a space station and vehicles to go to Mars and no researchers to answer the questions of what do we do when we get there," said Simon Ostrach, an emeritus professor of engineering at Case Western Reserve University whose former research center is among those losing NASA funding. Conceived decades before Bush in 2004 set NASA on a new quest toward Mars, and requiring the heavy-lifting capabilities of the balky and aging shuttle fleet in order to complete it, the 206-ton station orbits Earth every 92 minutes. Less than 40 percent complete eight years after construction began, the station has by some estimates already cost more than $50 billion, yet it still can't accommodate more than three crew members--enough to operate and repair the station but only half the number needed to conduct a full schedule of research and experiments. Some critics argue that the space station has become a white elephant that is forcing NASA to extend the risky shuttle program--two orbiters, Challenger and Columbia, and their crews have been lost to explosions--while diverting funds from unmanned missions to Mars and other planets that have proven more scientifically fruitful. Neither is the station essential as a jumping-off point for sending humans back to the moon or on to Mars, they say. "I don't place the space station in the critical path for sending humans to the moon," said Wesley Huntress, director of the geophysical laboratory at the Carnegie Institution of Washington and a former NASA associate administrator for space science. "And frankly the science community will tell you it was never a very useful platform for doing science at all. It's not in the right orbit for lots of things, and it's a very noisy environment." NASA officials say they are utilizing the space station as much as possible for experiments to understand the effects of long-term spaceflight on the human body. If humans are to endure years-long missions to Mars, researchers must find ways to protect them from such known issues as radiation exposure and bone and muscle loss due to low gravity. Scaling back on studies "We have tried to give the highest priority to the research that we need to get to the moon and Mars and beyond," said astronaut Donald Thomas, the space station's program scientist. "Is the science scaled back? You bet it is. But is it no science at all? No. We're still trying to utilize this station all we can up there." But a National Research Council review of NASA's space station plans in November criticized the space agency for failing to define how the station can be used to conduct research in support of long-duration space missions. And among the science programs recently cut by NASA were plant and animal research that might have answered such questions as how astronauts on the moon and Mars could grow their own food. A large centrifuge that could have duplicated the low-gravity conditions on the moon and Mars also was scrapped from the list of space station experiments. "The decision to remove fundamental science removes animal studies that were directly relevant to problems humans would experience for longer periods in space," said Mary Jane Osborn, a professor at the University of Connecticut Health Center and chairwoman of the council's review panel. "All in all, the situation looks at least as bleak if not bleaker than it did last November." Despite the science cuts, NASA officials insist they remain committed to the space station. Yet at Space Center Houston, the Johnson Space Center's visitor center and one of the agency's showcase attractions, the space station feels like an afterthought. Faulty showcase A big-screen film about the space station was made in 2000 and heralds projects such the Crew Escape Vehicle and the Orbital Space Plane that have since been abandoned. A virtual reality tour of the station features broken computers and graphics that pale in comparison to the simplest video games. Even if NASA wanted to back away from the space station, officials say that promises made to 15 nations participating in the project compel the United States to complete the station's construction. Russia, Canada, Japan and the European Space Agency have all spent billions on space station modules and experiments that require launch aboard the space shuttle. One area that has not been cut from the space station is product placements and commercial publicity stunts, which generate cash for the partner nations. This summer, a Russian cosmonaut is scheduled to hit a gold-plated golf ball off the station during a spacewalk in a promotion for a Canadian golf club manufacturer. In 2001, Pizza Hut paid the Russians to deliver a pizza to the space station. ---------- Then we have Japan considering a pull out over costs: Daily Yomiuri "The government should take the U.S. postponement of the next space shuttle launch and its potential impact on the building of the International Space Station more seriously. ... Prospects for a successful completion of the program are dimming. The issue is not only about space shuttle launch costs. Tokyo will be responsible for annual ISS running costs of about 40 billion yen [~$340 million USD], although it has not been determined how many years the station will remain operational after it is completed." Posted by kcowing at 12:11 PM | |
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Of tanks, foam and culture
"Brian Gaff" wrote:
:Has anyone ... :A: found out what settlement you could get with the international partners :if you said you could not fulfil your part of the deal? Probably be cheaper to just take the risk and fly them. :B: thought about seeing if any of the equipment could be flown on :conventional rockets? Some of them are too big. :Talked to the partners about some form of compromise where the US would pay :dev. costs for them to build a launcher to carry the parts to orbit. This one is merely crazy. Developing the launcher is the expensive part. If we had the funds to do that, why would we want to give them to someone else to do the job? :Seems to me that the ISS is a white elephant itself, and maybe a smaller :system perhaps several, might be a better answer. Well, there is that. ISS as built is not what we originally set out to do. Too many redesigns, rescopes, etc. -- "It's always different. It's always complex. But at some point, somebody has to draw the line. And that somebody is always me.... I am the law." -- Buffy, The Vampire Slayer |
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Of tanks, foam and culture
"Brian Gaff" wrote in message
k... I read the articles above. Discounting the range safety one as it was pre Columbia, and I think, a different issue, I do feel that the one question which is never going to be answered is,'how much foam can you lose'. Seems to me that if you want to be brutally honest, there is a design flaw, and all you can do is patch it up so that minimal size of the shed areas is below catastrophic damage constraints. However, nobody really knows what these parameters are. In CAIB hearings they said the original spec was 0.006 foot pounds per impact, maximum. That's so small it means virtually no impacts. At first NASA probably assumed it would be solved, then after the first missions, became accustomed to it (normalization of deviance). Because of Columbia they want to totally solve the problem. But even if not completely solved, with the few remaining flights, and going only to ISS (except possibly one Hubble mission), the risk of fatality from foam-induced TPS problems seems relatively small. Unless they have an abort, ISS will do a thorough TPS inspection. The Hubble mission will be different, but it's just one mission, and they have other techniques for inspecting it. So even if the foam shedding problem isn't totally solved, it seems livable considering the limited remaining flights. You have to take some risks. Everybody is focusing on TPS, but ascent-related problems (SSME, APU, etc) are still probably a greater risk. -- Joe D. |
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Of tanks, foam and culture
The caib's final conclusions lacked correlation of actual data
detecting cause (foam impact of the magnitude on jan 16, 2003 by on board sensors), to their theorized effect (forces imparted by impacting foam to at a great enough magnitude to cause rcc damage). Nor did the caib provide correlation damage amongst its many test results for thermal events, and actual damage caused by the foam to the flight day 2 object (140 sq inch object) that represented fragments of the alleged impact. |
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Of tanks, foam and culture
Listed below are 2 examples of the caibs lack of correlation of actual
data detected on coumbias ascent jan16, 2003, and foam impact damaging columbias wing to the extent claimed in their foam impact theory. #1 Please see graphs pertaining to the accelerometer on the left wing elevon (V08D9729A), (Caib report vol5 part d13 page 604,605) At 0.13 seconds after impact excitation the magnitude of the wave detected by the accelarometer from impact testing is matching the wing 3rd bending mode in magntude and period, where the signal should have been detected by columbias on board accelerometers on jan 16 2003. Please note foam impact FI=0 at MET +81.9 seconcd, and the graph listed by the caib on page, shows the wave closest matching the wing 3rd bending mode and dampening at a slow decreasing rate, meaning at MET +82 seconds the impact excitation wave was still detectable by accelerometer (V08D9729A) sampling at 10 times a second. Instead the caib states “the most compared” is the 2nd wing bending moment, which completely disregards the closer match of 3rd wing bending moment to the excitation pattern from the force of impact. Then the caib states the differences between test results and actual sts-107 flight data could be caused by difference of impact location, as the reason for not aknolegding the 2nd wing bending mode. #2 Foam impact was determined to have occurred at MET +81.9, the detailed examination by boeing determined excitation in the wing started at MET +81.7, 0.2 seconds before foam impact, thefefore foam impact was not the stimulation for the force revealed from boeings’ analysis from data during sts-107’s ascent on jan 16, 2003. The caib did not provide or demonstrate a correlation to the columbia’s on board sensors detecting a foam impacting to the magnitude required for rcc failure on jan 16 2003, and their own foam impact testing, therefore the caibs theory has not been validated. caib report vol v part 13 page 608 par 1 “7.3.3.1 Ascent All STS-107 MADS PCM strain data, without exception, was nominal during the ascent flight regime. Nosignificant anomalies were noted. Comparison of ascent strain gage load indicators showed STS-107 ascent loads to be within the family of previous OV-102 flight experience. There was no discernable evidence of an impact load to the vehicle near MET +81.7 seconds. At the PCM sample rate of 10 samples per second, no such evidence is expected to be present. Both the extremely short duration of the impact load (0.003 to 0.005 seconds), and the range of wing modes (6 Hz and above) preclude such evidence. An interesting signature near this time was evident in some strain gages. The response was noted on left wing, right wing, and vertical tail gages. Further study and scrutiny showed that the signature was inconsistent with impact loading, and attributable to a nominal ascent load response. A review of accelerometer data did show signatures consistent with impact loading. This assessment is discussed in Section 7.4.” Caib report vol 1 page 34 col 2 par 3 “Debris Strike Post-launch photographic analysis showed that one large piece and at least two smaller pieces of insulating foam separated from the External Tank left bipod (–Y) ramp area at 81.7 seconds after launch. Later analysis showed that the larger piece struck Columbia on the underside of the left wing, around Reinforced Carbon-Carbon (RCC) panels 5 through 9, at 81.9 seconds after launch (see Figure 2.3-2).” caib report vol 2 part d19 page 567-568 col 2 par The wideband FDM data, which because of its more com-plex encoding took longer to extract from the OEX recorder tape, also showed some signatures which are indicative of a debris strike near to 82 sec MET. One of the accelerometers on the left wing elevons, V08D9729A, showed a single cycle sinusoidal pulse at 81.9 sec MET that was approximately 2 g in amplitude, as compared to a background vibration level which generally stayed well below 1 g. This is a fairly sig-nificant pulse which could easily represent a strike of foam debris upon ascent. The timing and amplitude of this pulse were taken from a preliminary assessment of the wideband FDM data that was printed out on a strip chart recorder by NASA at JSC. Boeing of Huntington Beach performed a more thorough analysis of the remainder of the wideband FDM ascent data and in general did not find much that was anomalous. They found that the overall noise levels and power spectral density (PSD) matched very closely to the data from the pre-vious flight, STS-109. They noticed that at approximately 40 sec MET, the vertical stabilizer had some of its higher order modes growing slightly larger than normal, and this was attributed to some wind buffeting that was thought to occur around this time. These modes then decayed shortly thereafter, indicating that the so-called flutter instability was not becoming excited, as can occur when the wing bending modes and the fuselage vertical modes coalesce into a single coupled oscillation. Boeing.s analysis also pointed out that the recorded accelerations along the longeron were normal. Detailed analysis of the wideband FDM data over the time frame around 80-85 sec MET was performed. For the left outboard elevon accelerometer, V08D9729A, several wing and elevon oscillation modes were found to be excited during this time, with the strongest being a second order wing bending mode that matched best to the fundamental component of the single cycle sinusoidal pulse at 81.9 sec MET. Boeing.s more detailed time scale showed the period of the single sinusoidal pulse to extend over 81.70 to 81.74 sec MET, reaching +3.0 g on the positive peak at 81.71 sec MET, and *2.6 g on the negative peak at 81.72 sec MET. In addition, another accelerometer on the right wing, V08D9766A, showed a 1.5 cycle sinusoidal pulse response at a slightly earlier time of around 80 sec MET. This accel-erometer was located at the coordinates (X1367.0, Y+312.0, Z) towards the middle of the right wing and was sensitive to Z-axis motion. This accelerometer recorded an anomalous pulse beginning at 80.22 sec MET, growing to a first positive peak of +1.5 g at 80.23 sec MET, reaching a negative peak of *1.9 g at 80.24 sec MET, then another positive peak of +2.0 g at 80.26 sec MET, before dying away beyond 80.27 sec MET. The best fit to these peaks was a combination of outboard elevon torsion and the first wing bending mode. There have not been any explanations offered for the cause of this right wing accelerometer response. “ Caib report vol5 part d13 page 602 7.4.1.1 Evaluation of Peak Response at ~82 Seconds An in-depth study was made to investigate if the peak responses observed at the left outboard elevon accelerometer at ~82 seconds is due to the debris impact. Normally, sharp spikes in acceleration are observed at times during the ascent phase of the flight due to buffeting event(s). The buffeting load is most significant during the transonic region. However, it still exists at higher Mach numbers, which resultsin structural excitation. Shown in Figure 7.4-7 is the left and right outboard elevon comparison for the 10 second period near 82 seconds. The peak response is noticeable only for the left outboard location. Filtered responses presented in Figure 7.4-8 verify several wing/elevons were excited at 82 seconds. The 2nd wing bending response constitutes the largest component of the peak amplitude. In addition, the responses of 3rd wing bending and elevon torsion modes contributed to the peak response. Caib report vol5 part d13 page 603 “To determine if the debris impact can cause the type of responses observed in the flight data, analyses were performed using the FEM model of the wing combined with the reduced model of the Orbiter, which provides the back-up structure’s stiffness and mass (Figure 7.4-9). An impulse of 3,000 lbs force (with 0.005 second duration) in Z-direction was applied to the node closest to the RCC panel #8. The impulse of this magnitude is reasonable for a 1.5 lb object with a velocity of 530 MPH impacting the surface at 15 degrees inclination.” Caib report vol5 part d13 page 604 “Shown in Figure 7.4-10 is the recovered acceleration at the left outboard elevon location from the transient analysis. The FFT (Figure 7.4-11) of the response indicates excitation of several wing modes, including wing’s 2nd and 3rd bending modes. The filtered responses shown in Figure 7.4-12 illustrate the 3rd wing bending mode constitutes the majority of the peak amplitude, while the 2nd wing bending and elevon torsion modes also contribute to the peak response. The acceleration computed using the FEM model is shown along with the flight measured data in Figure 7.4-13. The shapes of acceleration signatures are comparable at the onset of debris impact. The frequency from the analysis is higher, since the 3rd wing bending mode is excited the most compared with the 2nd wing bending mode experienced during STS-107. More pronounced 3rd wing bending response from analysis could be attributed to possible deviations from the assumed location and duration of impact event, and some uncertainty in the FEM models for higher order wing modes. Nevertheless, similar acceleration signature and the excitation of higher order wing modes from the analysis indicate that the debris impact quite possibly could have caused the peak acceleration on the left outboard elevon at ~82 seconds in addition to other aerodynamic disturbances, such as buffeting and shocks. An absence of additional sensors on the left wing make it difficult to make conclusive remarks.” |
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