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Fast Flashing 2004-021B
Thanks very much for taking the time to write and provide the link! If I'm
having problems with the Internet I usually assume it has something to do with America Online. I've enjoyed reading the posts on SeeSat-L and learned much from them, though I admit I've barely started the learning curve when it comes to serious satellite observing. My observing so far has been limited to finding interesting objects on the Heavens Above site that are passing over my area and then going out to look at them, making magnitude estimates (this is just second nature to someone who has followed variable stars for years) and getting a rough idea of the rotation period if the object I look at is flashing. I'll try version 9.0 (or take the advice of friends and get a new ISP) and see if this works, though I'm not sure that anything I report could be considered good data yet. Thanks again, Paul Zeller Indianapolis, IN |
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Fast Flashing 2004-021B
Ed Cannon wrote:
By the way, besides Okean O Rk, quite a few other Zenits started out as fast tumblers. They have all slowed down or even stopped. Do you know if any of them have broken up before they slowed down? I estimate that 2004-021B is spinning at 45 RPMs; if it's 11 meters long and the axis is at its midpoint, then the ends experience a centripetal acceleration of approximately 12 Gs. That seems like a lot of stress for something that must have been built to take lower accelerations. I've tried to track down various Zenit-2 launchers through the astronautix.com and heavens-above archives, but so far I've only found one potential break-up candidate: 98-043, which may have shed a few parts weeks after its launch. Incidentally, I tracked 2004-021B a short while ago. It transited Cygnus from my location, as did the Kosmos 2237 booster. They were both heading north, with a separation of about 15 degrees, and almost seemed to be flying in formation. It was a remarkable sight. --Bill Thompson |
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Fast Flashing 2004-021B
Ed Cannon wrote:
By the way, besides Okean O Rk, quite a few other Zenits started out as fast tumblers. They have all slowed down or even stopped. Do you know if any of them have broken up before they slowed down? I estimate that 2004-021B is spinning at 45 RPMs; if it's 11 meters long and the axis is at its midpoint, then the ends experience a centripetal acceleration of approximately 12 Gs. That seems like a lot of stress for something that must have been built to take lower accelerations. I've tried to track down various Zenit-2 launchers through the astronautix.com and heavens-above archives, but so far I've only found one potential break-up candidate: 98-043, which may have shed a few parts weeks after its launch. Incidentally, I tracked 2004-021B a short while ago. It transited Cygnus from my location, as did the Kosmos 2237 booster. They were both heading north, with a separation of about 15 degrees, and almost seemed to be flying in formation. It was a remarkable sight. --Bill Thompson |
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Fast Flashing 2004-021B
William R. Thompson wrote:
Ed Cannon wrote: By the way, besides Okean O Rk, quite a few other Zenits started out as fast tumblers. They have all slowed down or even stopped. Do you know if any of them have broken up before they slowed down? Russel Eberst pointed out in an e-mail that the Kosmos 2227 booster (92-093B) broke up into some two hundred pieces. If the Zenit-2 upper stage has been strengthened since then, it might not happen again; on the other hand, it gives me a reason to keep watching 04-021B --Bill Thompson |
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Fast Flashing 2004-021B
William R. Thompson wrote:
Ed Cannon wrote: By the way, besides Okean O Rk, quite a few other Zenits started out as fast tumblers. They have all slowed down or even stopped. Do you know if any of them have broken up before they slowed down? Russel Eberst pointed out in an e-mail that the Kosmos 2227 booster (92-093B) broke up into some two hundred pieces. If the Zenit-2 upper stage has been strengthened since then, it might not happen again; on the other hand, it gives me a reason to keep watching 04-021B --Bill Thompson |
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Fast Flashing 2004-021B
If the Zenit-2
upper stage has been strengthened since then, it might not happen again; on the other hand, it gives me a reason to keep watching 04-021B That's a really fascinating idea, Bill. Thanks, it gives me more reason to track it as well! Okean O (1999-039B) (25861) was an eye-catcher soon after launch. I was able to see it just three weeks after it was launched in 1999, and it was flashing like a strobe light! I went out to observe it after reading about it on H-A. I sort of fell away from satellite observing for a while after that summer and didn't observe it again until the spring of 2001. I saw it shining with a steady brightness on that pass, and on eight or nine passes since then. Can such a rapid tumble in an orbiting rocket stop after less than two years? Or was I just catching this object at the wrong orientation every time and missed any kind of flash period? I've always wondered this. Paul Z Indianapolis |
#27
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Fast Flashing 2004-021B
If the Zenit-2
upper stage has been strengthened since then, it might not happen again; on the other hand, it gives me a reason to keep watching 04-021B That's a really fascinating idea, Bill. Thanks, it gives me more reason to track it as well! Okean O (1999-039B) (25861) was an eye-catcher soon after launch. I was able to see it just three weeks after it was launched in 1999, and it was flashing like a strobe light! I went out to observe it after reading about it on H-A. I sort of fell away from satellite observing for a while after that summer and didn't observe it again until the spring of 2001. I saw it shining with a steady brightness on that pass, and on eight or nine passes since then. Can such a rapid tumble in an orbiting rocket stop after less than two years? Or was I just catching this object at the wrong orientation every time and missed any kind of flash period? I've always wondered this. Paul Z Indianapolis |
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Fast Flashing 2004-021B
PZeller66 wrote:
If the Zenit-2 upper stage has been strengthened since then, it might not happen again; on the other hand, it gives me a reason to keep watching 04-021B That's a really fascinating idea, Bill. Thanks, it gives me more reason to track it as well! I looked at the sites Ed Cannon posted (thank you, Ed!) and compared that against the debris lists on heavens-above. All of the Zenit-2s seem to shed some debris: the covers over four solid separation rockets. About a third of all Zenit-2s seem to have generated more debris than this, so there's a fair chance that something may happen. If my calculations are correct, debris will be shed at a maximum of 25 m/sec (about 60 mi/hr). That doesn't lead to a major change in orbit. Depending on the direction the junk flies off at, the debris's new orbit will lower its perigee/raise its apogee by up to 50 km, or change its inclination by about a fifth of a degree. If there's a major bit of debris shed, I'd expect the booster's tumble to slow as the debris carries off some momentum. Okean O (1999-039B) (25861) was an eye-catcher soon after launch. I was able to see it just three weeks after it was launched in 1999, and it was flashing like a strobe light! I went out to observe it after reading about it on H-A. I sort of fell away from satellite observing for a while after that summer and didn't observe it again until the spring of 2001. I saw it shining with a steady brightness on that pass, and on eight or nine passes since then. Can such a rapid tumble in an orbiting rocket stop after less than two years? Or was I just catching this object at the wrong orientation every time and missed any kind of flash period? I've always wondered this. I don't know how long it takes the tumblers to slow down; I think it depends on several factors--their size and mass, and the intensity of the Earth's magnetic field. As I understand it, magnetism is the major factor in slowing a satellite's tumble; the spin sets up eddy currents in the object. --Bill Thompson |
#29
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Fast Flashing 2004-021B
PZeller66 wrote:
If the Zenit-2 upper stage has been strengthened since then, it might not happen again; on the other hand, it gives me a reason to keep watching 04-021B That's a really fascinating idea, Bill. Thanks, it gives me more reason to track it as well! I looked at the sites Ed Cannon posted (thank you, Ed!) and compared that against the debris lists on heavens-above. All of the Zenit-2s seem to shed some debris: the covers over four solid separation rockets. About a third of all Zenit-2s seem to have generated more debris than this, so there's a fair chance that something may happen. If my calculations are correct, debris will be shed at a maximum of 25 m/sec (about 60 mi/hr). That doesn't lead to a major change in orbit. Depending on the direction the junk flies off at, the debris's new orbit will lower its perigee/raise its apogee by up to 50 km, or change its inclination by about a fifth of a degree. If there's a major bit of debris shed, I'd expect the booster's tumble to slow as the debris carries off some momentum. Okean O (1999-039B) (25861) was an eye-catcher soon after launch. I was able to see it just three weeks after it was launched in 1999, and it was flashing like a strobe light! I went out to observe it after reading about it on H-A. I sort of fell away from satellite observing for a while after that summer and didn't observe it again until the spring of 2001. I saw it shining with a steady brightness on that pass, and on eight or nine passes since then. Can such a rapid tumble in an orbiting rocket stop after less than two years? Or was I just catching this object at the wrong orientation every time and missed any kind of flash period? I've always wondered this. I don't know how long it takes the tumblers to slow down; I think it depends on several factors--their size and mass, and the intensity of the Earth's magnetic field. As I understand it, magnetism is the major factor in slowing a satellite's tumble; the spin sets up eddy currents in the object. --Bill Thompson |
#30
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Fast Flashing 2004-021B
The slowing of the tumble is actually more to do with a conductor (the
rocket) rotating and moving in a magnetic field (the earths) and slowing due to hysteresis effects..basically an induced current makes the rockets tumble slow down over time. pj "William R. Thompson" wrote in message ... PZeller66 wrote: If the Zenit-2 upper stage has been strengthened since then, it might not happen again; on the other hand, it gives me a reason to keep watching 04-021B That's a really fascinating idea, Bill. Thanks, it gives me more reason to track it as well! I looked at the sites Ed Cannon posted (thank you, Ed!) and compared that against the debris lists on heavens-above. All of the Zenit-2s seem to shed some debris: the covers over four solid separation rockets. About a third of all Zenit-2s seem to have generated more debris than this, so there's a fair chance that something may happen. If my calculations are correct, debris will be shed at a maximum of 25 m/sec (about 60 mi/hr). That doesn't lead to a major change in orbit. Depending on the direction the junk flies off at, the debris's new orbit will lower its perigee/raise its apogee by up to 50 km, or change its inclination by about a fifth of a degree. If there's a major bit of debris shed, I'd expect the booster's tumble to slow as the debris carries off some momentum. Okean O (1999-039B) (25861) was an eye-catcher soon after launch. I was able to see it just three weeks after it was launched in 1999, and it was flashing like a strobe light! I went out to observe it after reading about it on H-A. I sort of fell away from satellite observing for a while after that summer and didn't observe it again until the spring of 2001. I saw it shining with a steady brightness on that pass, and on eight or nine passes since then. Can such a rapid tumble in an orbiting rocket stop after less than two years? Or was I just catching this object at the wrong orientation every time and missed any kind of flash period? I've always wondered this. I don't know how long it takes the tumblers to slow down; I think it depends on several factors--their size and mass, and the intensity of the Earth's magnetic field. As I understand it, magnetism is the major factor in slowing a satellite's tumble; the spin sets up eddy currents in the object. --Bill Thompson |
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