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#1
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Any more news on the cargo ship problem?
Says it all really. I guess the problem could be a loot of things, but
generally the system seems robust so... Brian -- From the Sofa of Brian Gaff Reply address is active |
#2
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Any more news on the cargo ship problem?
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#4
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Any more news on the cargo ship problem?
In article om,
says... On 15-04-29 06:04, Jeff Findley wrote: No new news that I can see so far this morning. I'll have to do more research to get some hard facts instead of reporter digested text, but this seems pretty much hard to fail reporting: Out-of-control Russian spacecraft declared a total loss http://www.cbc.ca/news/technology/ou...loss-1.3053356 Space.Com does provide a few details. All went well until after solar array were deployed . Apparently, some antennas did not deploy. But there is video from the spacecract indicating it is spinning (which means that some sort of radio link did continue to function (and surprising that the video could be donwlinked considering spacecraft rotation and antenna contantly pointing at different location. In a situation where Progress loses comms with earth, does it have enough smarts to stabilize itself and continue the mission ? Or does it require ground send commands to actuvate various phases of flight ? Do we know if the Progress performed its second and subsequent burns to circulatize its orbit ? Recent reports say no confirmed burns performed by Progress. Furthermore, there is apparently no fuel left and a debris field being tracked. If not, how long before it creates nice fireworks in the sky as it falls back down ? It will reenter in a matter of days. It's a total loss. Jeff -- "the perennial claim that hypersonic airbreathing propulsion would magically make space launch cheaper is nonsense -- LOX is much cheaper than advanced airbreathing engines, and so are the tanks to put it in and the extra thrust to carry it." - Henry Spencer |
#5
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Any more news on the cargo ship problem?
In article om,
says... Interfax has a russian language text on the issue. http://www.interfax.ru/russia/439186 google translation: https://translate.google.com/transla...6 &edit-text= The rough translation says that all went well until 3rd stage. They say that the de-orbit may happen in early May. May 1 is Friday, so very soon. Jeff -- "the perennial claim that hypersonic airbreathing propulsion would magically make space launch cheaper is nonsense -- LOX is much cheaper than advanced airbreathing engines, and so are the tanks to put it in and the extra thrust to carry it." - Henry Spencer |
#6
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Any more news on the cargo ship problem?
In article om,
says... Question about debris: If a stage 3 separates before stage 2 has finished its burn, would it simply jump ahead of stage2 only to be caught by still accelerating stage 2 and the collision would then cause damaghe and debris ? Not necessarily. I believe that SpaceX had something very much like this happen on one Falcon 1 flight and it resulted in the lower stage recontacting the upper stage. Would would such a sepoaration not have enough "oumph" to allow stage 3 to separate from 2 because 2's acceleration is greater than the push that 3 makes to get ahead of 2 ? Or would depris point to an Apollo 13 style explosion ? An impact could certainly result in structural failure and rapid loss of pressure in one of the tanks. The "spinning" video at: http://www.space.com/29241-glitch-ru...rol-video.html Indicates more of an agena type of spin (from the HBO "From Earth to the Moon" along pitch axis rather than just a simple spin along yaw. Assuming this rotation continues, won't that mess up re-entry predictions ? Or would a rotating vehicle present fairly similar drag coefficient ? This is all estimation. You estimate the frontal area based upon the average area presented over time. So yes, the rapid, consistent, spinning allows for a better estimation of drag than for a vehicle is slowly tumbling (rotating in what appears to be a random manner). Are autopilots capable of recovering from such a extreme situation ? If "below" the horizon, the autopilot may command a raise in pitch to reach targhetted horizon, but that firing may accelerate the spin (when one should detect the spin and fire against it no natter what your current attitude is). I doubt the Progress "autopilot" is that capable. In a situation like this, the Russians would rely on remote control. But, with the spinning, reliable communications necessary to command Progress might be impossible. If you can't command it, it's not going to stop spinning. Depends on other details too. In this case, it appears there is no fuel left. If this means no fuel for the reaction control system then there is no chance to fix the spin no matter what. Off the top of my head, I don't know if the reaction control system shares fuel tanks with the main propulsion system on a Progress. Also, would solar panels still be able to feed Progress with enough power in this constant rotation to stay awake, or is the ship already asleep due to power starvation ? Depends on the details, but it's got some battery capacity too. I've not heard of power starvation problems. That could be a problem, but that's secondary compared with complete loss of fuel and/or the inability to command the Progress. We should all keep in mind that Progress and Soyuz are closely related. They fly on the same launcher and share many common systems (like the service module, which is likely where this mission failed). Without a reliable US manned space "taxi", the Russians had better figure this one out quickly in order to keep the station manned. Jeff -- "the perennial claim that hypersonic airbreathing propulsion would magically make space launch cheaper is nonsense -- LOX is much cheaper than advanced airbreathing engines, and so are the tanks to put it in and the extra thrust to carry it." - Henry Spencer |
#7
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Any more news on the cargo ship problem?
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#8
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Any more news on the cargo ship problem?
In article om,
says... Update: Gennady Padalka took pictures of the Progress passing underneath the station, but too far to reveal sufficient details on what could have happened. They will try again. A russian news source said that Progress' orbit decays by 100m per day. I assume this number will grow somewhat exponentially ? Yes, it's a positive feedback loop. You don't say if that's the drop in apogee or perigee. In the case of an elliptical orbit (Progress is said to have 190/270km) would eccentricity increase during orbital decay since at perigee, the ship slows down more than at apogee ? Or does the loss of energy ar perigee cause both apogee and perigee altitudes to drop at same rate ? Yes, the apogee drops more, in altitude, than the perigee due to he reduction in velocity at perigee. Would "re-entry" be defined as the time when the current perigee becomes apogee and perigee becomes "0" ? (lasting about half orbit) ? When it crashes to the ground, that's re-entry, IMHO. Since the atmosphere tapers off as altitude increases, there is no "hard line" which denotes where atmospheric entry "begins", other than on the last orbit, which the satellite never escapes again. Is this a sudden/violent change once perigee hits a certain altitude with perhaps the change of orbit to peridee=0 happening over 1 or two orbits, or is that smooth transformation over multiple days which ends up circularizing the orbit ? Are there situations where perigee would cause some heating of the ship which would then emerge from atmosphere to reach apogee and cool down, and drop into atmosphere again ? There is always some heating of the ship due to atmospheric drag. Less drag means less heating, but if you have drag, heating is present. References: Orbital decay http://en.wikipedia.org/wiki/Orbital_decay This links to an interesting paper by the Australians (Skylab, anyone?). See the last page of this document for what happens to an eliptical orbit which is (obviously) subject to more atmospheric drag at its perigee. Satellite Orbital Decay Calculations http://www.ips.gov.au/Category/Educa...Weather/Space% 20Weather%20Effects/SatelliteOrbitalDecayCalculations.pdf Jeff -- "the perennial claim that hypersonic airbreathing propulsion would magically make space launch cheaper is nonsense -- LOX is much cheaper than advanced airbreathing engines, and so are the tanks to put it in and the extra thrust to carry it." - Henry Spencer |
#9
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Any more news on the cargo ship problem?
"JF Mezei" wrote in message
eb.com... As an FYI, previous orbit, went from about 150 to about 164km. This orbit, went from 137.2 to only 139.1 over Kazakhstan And now over pacific, down to 135.5 So last full orbit almost circular (is 137/139 considered circular or still elliptical ?) I assume that the fireworks happen as same altitude as Shuttle ? NASA says 400,000feet or 123km. As I wrote this, Progress dropped to 134.7 from 135.5km altitude (beased on math model used by Satflare. I would expect it's similar. Somewhat it depends on the density of the craft I believe. (Consider the difference between trying to toss a baseball vs. nerf ball.) -- Greg D. Moore http://greenmountainsoftware.wordpress.com/ CEO QuiCR: Quick, Crowdsourced Responses. http://www.quicr.net |
#10
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Any more news on the cargo ship problem?
I see that they have effectively declared it a loss and in the news group it
seems that the launches are being rescheduled to allow the time to sort out what happened. Unfortunately it does not take much to create such a situation and as nobody can go and look at it, its got to be done using existing data. I bete its something really simple and stupid, these things usually are at the end of the day. However if it is diagnosed as a problem that could affect manned launches, then things get a lot more problematic. Brian -- From the Sofa of Brian Gaff Reply address is active "Jeff Findley" wrote in message ... In article om, says... Question about debris: If a stage 3 separates before stage 2 has finished its burn, would it simply jump ahead of stage2 only to be caught by still accelerating stage 2 and the collision would then cause damaghe and debris ? Not necessarily. I believe that SpaceX had something very much like this happen on one Falcon 1 flight and it resulted in the lower stage recontacting the upper stage. Would would such a sepoaration not have enough "oumph" to allow stage 3 to separate from 2 because 2's acceleration is greater than the push that 3 makes to get ahead of 2 ? Or would depris point to an Apollo 13 style explosion ? An impact could certainly result in structural failure and rapid loss of pressure in one of the tanks. The "spinning" video at: http://www.space.com/29241-glitch-ru...rol-video.html Indicates more of an agena type of spin (from the HBO "From Earth to the Moon" along pitch axis rather than just a simple spin along yaw. Assuming this rotation continues, won't that mess up re-entry predictions ? Or would a rotating vehicle present fairly similar drag coefficient ? This is all estimation. You estimate the frontal area based upon the average area presented over time. So yes, the rapid, consistent, spinning allows for a better estimation of drag than for a vehicle is slowly tumbling (rotating in what appears to be a random manner). Are autopilots capable of recovering from such a extreme situation ? If "below" the horizon, the autopilot may command a raise in pitch to reach targhetted horizon, but that firing may accelerate the spin (when one should detect the spin and fire against it no natter what your current attitude is). I doubt the Progress "autopilot" is that capable. In a situation like this, the Russians would rely on remote control. But, with the spinning, reliable communications necessary to command Progress might be impossible. If you can't command it, it's not going to stop spinning. Depends on other details too. In this case, it appears there is no fuel left. If this means no fuel for the reaction control system then there is no chance to fix the spin no matter what. Off the top of my head, I don't know if the reaction control system shares fuel tanks with the main propulsion system on a Progress. Also, would solar panels still be able to feed Progress with enough power in this constant rotation to stay awake, or is the ship already asleep due to power starvation ? Depends on the details, but it's got some battery capacity too. I've not heard of power starvation problems. That could be a problem, but that's secondary compared with complete loss of fuel and/or the inability to command the Progress. We should all keep in mind that Progress and Soyuz are closely related. They fly on the same launcher and share many common systems (like the service module, which is likely where this mission failed). Without a reliable US manned space "taxi", the Russians had better figure this one out quickly in order to keep the station manned. Jeff -- "the perennial claim that hypersonic airbreathing propulsion would magically make space launch cheaper is nonsense -- LOX is much cheaper than advanced airbreathing engines, and so are the tanks to put it in and the extra thrust to carry it." - Henry Spencer |
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