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First NASA Soyuz TMA-11 documents
More info from James Oberg
http://www.spectrum.ieee.org/may08/6229 This is interesting: "However, a suggestive detail in the postlanding photography, a thruster mounting with jagged gaps alongside it, indicates that an attitude thruster burned through. Such damage would have reduced or even entirely eliminated the crew's ability to point the crew module during descent. The thruster could have been lost as a consequence of a vain attempt to steer the much-heavier-than-expected combined vehicle through the initial buffeting." Soyuz TMA RV thrusters use simple hydrogen peroxide decomposition to generate thrust, so you'd think the comparatively low temperatures involved wouldn't burn through a thruster... was the thruster damaged during reentry? Another interesting section: "In addition, Yi So-yeon, the South Korean flight participant, reported in interviews in Seoul that the final ground impact was not vertical but sideways, causing many heavy baggage items to break free from restraints and hit her." After parachute deployment the capsule is supposed to fire a system that releases a bridle from the side-mounted parachute housing that then swings up over the top hatch, so that the capsule is descending vertically under the chute. If it did hit sideways, that suggests something went wrong with the bridle release and in that case the landing rockets wouldn't cushion the landing much on impact. Pat |
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First NASA Soyuz TMA-11 documents
On May 7, 4:19*pm, Pat Flannery wrote:
More info from James Oberghttp://www.spectrum.ieee.org/may08/6229 This is interesting: "However, a suggestive detail in the postlanding photography, a thruster mounting with jagged gaps alongside it, indicates that an attitude thruster burned through. Such damage would have reduced or even entirely eliminated the crew's ability to point the crew module during descent. The thruster could have been lost as a consequence of a vain attempt to steer the much-heavier-than-expected combined vehicle through the initial buffeting." Soyuz TMA RV thrusters use simple hydrogen peroxide decomposition to generate thrust, so you'd think the comparatively low temperatures involved wouldn't burn through a thruster... was the thruster damaged during reentry? Another interesting section: "In addition, Yi So-yeon, the South Korean flight participant, reported in interviews in Seoul that the final ground impact was not vertical but sideways, causing many heavy baggage items to break free from restraints and hit her." After parachute deployment the capsule is supposed to fire a system that releases a bridle from the side-mounted parachute housing that then swings up over the top hatch, so that the capsule is descending vertically under the chute. If it did hit sideways, that suggests something went wrong with the bridle release and in that case the landing rockets wouldn't cushion the landing much on impact. Pat Pat, You seem to have an understanding of Soyuz systems. Although not related (as best we know) to the current TMA-11 issue, I wonder if you may have some historical information. On the Soyuz spacecraft used today, a radar altimeter is used to cue the firing of the braking rockets immediately before landing. However, earlier versions of Soyuz used a radiometric system similar to a gamma backscatter gauge that measured radiation scattered back from the ground as the vehicle approached touchdown. If I remember correctly the system used a Cobalt 60 source. The location of the source on the bottom of the vehicle was marked by the international yellow and magenta radiation symbol. But that is all I know (and I am iffy on some of that information). Do you have any specific information on this system, especially: 1. The isotope and the activity of the source, in either Becquerels (SI units) or curies (traditional units). 2. The resultant radiation exposure or dose rates in the interior of the reentry vehicle (again in either SI or traditional units)? I have goggled for this information several times and even posted the question here on the newsgroup a couple of years ago, without success. Thank you in advance for any information or internet references you might be able to share. Blue skies to all, John |
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First NASA Soyuz TMA-11 documents
John wrote: Do you have any specific information on this system, especially: 1. The isotope and the activity of the source, in either Becquerels (SI units) or curies (traditional units). 2. The resultant radiation exposure or dose rates in the interior of the reentry vehicle (again in either SI or traditional units)? I have goggled for this information several times and even posted the question here on the newsgroup a couple of years ago, without success. Thank you in advance for any information or internet references you might be able to share. Nothing on the TMA version, but both the radioactive and radar firing systems for the landing rockets aren't going to work right if it doesn't land vertically. In that case you are going to hit very hard, then (if you are lucky) the landing rockets aren't going to go off...or if you're not.... they are going to fire and blow the capsule around after its initial surface impact. From what little I've read about the specifics of the TMA-11 landing, it sounds a lot like the latter occurred. That would account for the fire and description of it rolling around after bouncing off of the ground on the initial impact. The burn time of the landing rockets is very short (around a second?)...but they generate one hell of a lot of thrust while firing. Whatever happened, this was a _way_ off-nominal reentry and landing. It would be interesting to get specific details of the TMA-10 reentry and landing aberrations, though I doubt we will. Hitting the atmosphere with the service module still attached and having it burn off as heating an aerodynamic loads built up would scare me a lot less than having it separate and still having it attached by the umbilicals between it and the reentry module; in that case it could be batting into the heatshield as reentry began and damaging it before it fell away. Several of the Vostoks came in like that, with their reentry spheres still attached by their umbilicals, but in that case the service module would have ended up basically above the reentry sphere as it descended until falling free. In the case of Soyuz, the service module would end up hanging at around a ninety degree angle from the the Soyuz RV's heatshield, so that the crew would be entering head-first till it separated. Unfortunately, that's the side of the RV the parachute ejection hatches are mounted on, and they could be damaged by the heat, like what happened during the Soyuz 5 reentry. Our astronaut's statement that deceleration was _feet-first_ indicates that that wasn't the case, and the whole service module stayed attached till its attachments to the RV burned away, like in the case of Soyuz 5. The solar arrays on the equipment module and forward center of mass of the combined vehicle means that during the initial interaction with the atmosphere the combined RV/SM is going to come in like a finned bomb - nose end first. In the case of Soyuz 5, the two modules apparently separated when the hypergolic propellants in the SM cooked off and blew it to pieces. Pat |
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First NASA Soyuz TMA-11 documents
In the case of Soyuz 5, the two modules apparently separated when the hypergolic propellants in the SM cooked off and blew it to pieces. Pat Goood Grief!!!!!!!!!!! |
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First NASA Soyuz TMA-11 documents
John wrote: In the case of Soyuz 5, the two modules apparently separated when the hypergolic propellants in the SM cooked off and blew it to pieces. Pat Goood Grief!!!!!!!!!!! Yeah, Volynov heard quite a bang when the tanks blew; here's the description of the reentry from the book "Challenge to Apollo": "Six seconds after the termination of retrofire, Volynov heard the pyrocartridges triggering to separate the three major modules of the spacecraft: the living compartment, the descent apparatus, and the instrument-aggregate compartment. As he looked through the viewport, he noticed something deadly wrong: he could clearly see the antennas attached to the solar arrays on the cylindrical instrument-aggregate compartment, meaning that the section, also known as the service module, had not separated from the descent apparatus. While similar failures had occurred on early Vostok and Voskhod flights, it posed a much greater threat on Soyuz because of the relatively huge size of the module. Volynov immediately reported in code to ground controllers about his predicament. Most simply believed that Volynov had little chance to live? The descent apparatus tumbled in somersaults as it remained attached to the three-ton service module and began its long journey through the atmosphere. Turning over and over, with the thermal shield unexposed to the heat because it was still covered by the service module, the heat began to affect unprotected portions of the descent apparatus. Smoke began to appear within the capsule as the light heat insulation began to burn. Normally, during a reentry, hydrogen peroxide jets would fire during this period to guide the capsule to provide lift and reduce thermal and gravitational stresses. In this case, Volynov noticed that his instrument panel indicated that the valves for the thrusters were open, but there had been no firings. All the propellant had been used up at the initiation of retrofire, when the computer had tried in vain to correct the spaceship's incorrect attitude. Volynov recalls that he was sure that only a few minutes separated him from death. The normally unflappable cosmonaut considered saying goodbye to his relatives, but instead decided to hurriedly save all the recorded materials on the docking procedure by ripping the important pages from the log book, rolling them up tightly, and sticking them into the middle of the book. Then, amid the cauldron around him, he calmly began to speak into a tape recorder, describing all the details of his experience to assist in identifying the reasons for the failure. Through it all, there were terrifying moments. Once, there was a sharp clap, indicating that the propellant tanks of the service module had blown apart with such force that the crew hatch was forced inwards and then upwards like the bottom of a tin can. Plummeting through a ballistic trajectory, he realized that the service module had finally disintegrated and he had survived. His relief soon turned to anxiety when the parachute system triggered at an altitude of ten kilometers. The straps on the main parachute began to twist, preventing them from unfurling properly. For the second time in minutes, he was convinced of his end, Remarkably, the braids of the parachute began to untwist slowly: by the time that the descent apparatus landed with its soft-landing engines, it was sufficient to ensure Volynov's safety, although the landing was so hard that the roots of his teeth in his upper jaw were broken off. It was only the specially built shock-absorbing seat that saved him from broken bones and more serious injuries." Pat |
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First NASA Soyuz TMA-11 documents
On May 10, 4:33*am, Pat Flannery wrote:
John wrote: In the case of Soyuz 5, the two modules apparently separated when the hypergolic propellants in the SM cooked off and blew it to pieces. Pat Goood Grief!!!!!!!!!!! Yeah, Volynov heard quite a bang when the tanks blew; here's the description of the reentry from the book "Challenge to Apollo": "Six seconds after the termination of retrofire, Volynov heard the pyrocartridges triggering to separate the three major modules of the spacecraft: the living compartment, the descent apparatus, and the instrument-aggregate compartment. As he looked through the viewport, he noticed something deadly wrong: he could clearly see the antennas attached to the solar arrays on the cylindrical instrument-aggregate compartment, meaning that the section, also known as the service module, had not separated from the descent apparatus. While similar failures had occurred on early Vostok and Voskhod flights, it posed a much greater threat on Soyuz because of the relatively huge size of the module. Volynov immediately reported in code to ground controllers about his predicament. Most simply believed that Volynov had little chance to live? The descent apparatus tumbled in somersaults as it remained attached to the three-ton service module and began its long journey through the atmosphere. Turning over and over, with the thermal shield unexposed to the heat because it was still covered by the service module, the heat began to affect unprotected portions of the descent apparatus. Smoke began to appear within the capsule as the light heat insulation began to burn. Normally, during a reentry, hydrogen peroxide jets would fire during this period to guide the capsule to provide lift and reduce thermal and gravitational stresses. In this case, Volynov noticed that his instrument panel indicated that the valves for the thrusters were open, but there had been no firings. All the propellant had been used up at the initiation of retrofire, when the computer had tried in vain to correct the spaceship's incorrect attitude. Volynov recalls that he was sure that only a few minutes separated him from death. The normally unflappable cosmonaut considered saying goodbye to his relatives, but instead decided to hurriedly save all the recorded materials on the docking procedure by ripping the important pages from the log book, rolling them up tightly, and sticking them into the middle of the book. Then, amid the cauldron around him, he calmly began to speak into a tape recorder, describing all the details of his experience to assist in identifying the reasons for the failure. Through it all, there were terrifying moments. Once, there was a sharp clap, indicating that the propellant tanks of the service module had blown apart with such force that the crew hatch was forced inwards and then upwards like the bottom of a tin can. Plummeting through a ballistic trajectory, he realized that the service module had finally disintegrated and he had survived. His relief soon turned to anxiety when the parachute system triggered at an altitude of ten kilometers. The straps on the main parachute began to twist, preventing them from unfurling properly. For the second time in minutes, he was convinced of his end, Remarkably, the braids of the parachute began to untwist slowly: by the time that the descent apparatus landed with its soft-landing engines, it was sufficient to ensure Volynov's safety, although the landing was so hard that the roots of his teeth in his upper jaw were broken off. It was only the specially built shock-absorbing seat that saved him from broken bones and more serious injuries." Pat Pat, Do you have any information on the gamma backscatter altimetry system? Thanks John |
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First NASA Soyuz TMA-11 documents
John wrote: Pat, Do you have any information on the gamma backscatter altimetry system? Not specific details on it, but the isotope used on it to generate the backscatter off of the ground that fires the landing rockets was powerful enough that the rear bulkhead on the Soyuz unincorporated both a radiation warning insignia on it and visual warnings not to stand behind the reentry module if it was laying on its side. It's a very strange way of firing the landing rockets, but you can see how it works... there's something like a downward pointing Geiger counter on the capsule's bottom once the heatshield is jettisoned that picks up the backscatter from the isotope as it bounces off of the ground, and is attenuated by the atmosphere between the isotope itself and the backscatter detector in secondary radioactive forms till it reaches the detector. That's probably Alpha backscatter radiation, if the isotopic emitter was powerful enough. Their air-dropped tanks (and I suspect the Voskhods from the same period) used a deployed lanyard that fired the landing rockets when it physically touched the ground from around 5-10 feet altitude (Voskhod's landing rockets were mounted at the base of the shroud lines of its parachute, as were the VA lander's from the TKS module). Pat |
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