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Wild Flashing Rocket Body

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#1 PaulZPA

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Posted 21 June 2012 - 03:29 AM

Before dawn on Wed. June 20th I was outside with binoculars and spotted a really awesome satellite. I used 7X50 binoculars to watch it pass from Cassiopeia through Cygnus and Delphinus. It seemed to not only wax and wane in brightness quickly but also had bright sharp flashes every now and then. A check of Calsky.com told me that I was looking at the GCOM W1 Rocket 2012-025E #38341, launched a little over a month ago last May 19th. It also gave a good pass prediction for the following morning. This morning (Thu. June 21) I was out at 4AM again with the binoculars and watched it pass from Ursa Minor to Draco and Lyra and then disappear in Serpens. This time I made a rough timing with a kitchen timer and it seems to wax and wane in brightness every 7-8 seconds from about 2nd - 4th magnitude but it also had the same sudden sharp flashes that seem to come and go almost at random. The sharp flashes remind me of what one would see when sunlight hits a solar panel, but why would a rocket body be equipped with one? Is anyone else out there observing this interesting object, or is anyone into flashing / tumbling satellites? This is a good target for anyone interested.

#2 PaulZPA

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Posted 21 June 2012 - 03:35 AM

One more question - maybe a dumb one. I realize that NEO is probably for near earth asteroids, but is this also where observers post artificial satellite observations? Do I have the wrong forum, and does one for satellites exist? Just curious!

#3 WillCarney

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Posted 21 June 2012 - 09:27 AM

First NEO while typically has meant only asteroids in the past here it does cover all Near Earth Objects. That would include satellites. They are near Earth. Till a new forum is made that is. There were a few hassles about a few comets but when pointed out that they did indeed have close approaches to Earth they too are called NEO's.

The flashes are typical. What you are indeed seeing is the tumble and rotation of the rocket body. Pick up a soda can for instance. If you look at the can end-on it's small. If you look at the can side ways it's long and bigger. If you look at the can at an angle it's bigger than end-on but smaller than side on. The Sun reflects on this body in various amounts depending on rotation. All rocket bodies will rotate or tumble. Remember only active satellites generally don't rotate or tumble. Rocket bodies will, they don't have stabilization.

I have picked up rotation and tumble in near Earth asteroid pictures. You can actually see the asteroid get dimmer or brighter in it's trail as it tumbles and rotates.

William

#4 PaulZPA

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Posted 22 June 2012 - 12:20 PM

Thanks Will for your reply. Your explanation of why rocket bodies seem to change brightness because of rotation was educational for novice satellite observers. I've watched them off and on for the last 30 years and one of my goals lately has been to look for rockets from recent launches (since they are the most likely to rotate and flash) and see how the flash period changes over time. Hopefully someday I'll get some video equipment and get some more accurate timing/brightness/position information. The thing that impressed me about this particular rocket wasn't the broader waxing and waning in brightness due to the tumble but the sharp bright flashes that seemed to appear more randomly. I am wondering if this object has something very reflective on the outside catching glints of sunlight.

#5 WillCarney

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Posted 22 June 2012 - 12:52 PM

Most will forget that rocket bodies don't have stabilization like satellites. The sharp bright flashes could also be the nature of the rocket body. Not all bodies are shiny and uniform on their body. They may have paint or paint that has been worn off. Apollo for instance had white and black on it's body for the most part. Under neath that you had the shiny metal. Loose paint and it will flare. When a rocket body stages the end that connects to the upper stage is generally not painted. As the bottom end is also not painted. So if you look end on you will get flashes from various hardware attached on the upper end. The bottom end also has bell nozzles and maybe piping that also will flare up causing flashes. There might be small panels like access panels that are missing or not painted that also flare. So you see there can be a lot of items on a rocket body that can flare suddenly and unpredictably. Just flashing quickly. Most newer observers think of flares like an Iridium but I have seen these sudden flares in satellites before. I even have seen this with a Shuttle or the ISS when a flare came off a small piece of hardware. There's an article about a UFO spotted over the Middle East. It was a Russian ballistic missile venting fuel after seperation and it made a classic "S" cloud of vapor as the rocket body tumbled. Very cool.

These events can be very neat.
William

#6 GlennLeDrew

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Posted 30 August 2012 - 04:15 PM

If there are flashes of very much shorter duration--and particularly if quite brighter--than the regular periodicity of brightness variation, this would suggest a surface flatter than a cylinder or cone being responsible for the flash.






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