Hello! Ted Molczan wrote: > The Phobos-Soil Project has requested precise positional observations > of the spacecraft during the two engine burns that will propel it out > of its LEO parking orbit and send it to Mars Since I am working at IKI in Moscow, I've talked to our Deputy Director, and he explained that one of the main tasks for observers is to record (and to report) the time of engine firings and cut-offs during two active parts of trajectory. This is important to make sure the booster has worked the correct amount of time required for the trajectory correction. > There are challenges for prospective observ/ers: > > - the spacecraft will be in eclipse (Earth's shadow) for nearly the > entire portion of both burns visible from land. > Fortunately, the exhaust plume is expected to be sufficiently bright > to be observed from the ground. I think SeeSat readres can help in bringing the light to the plausibility of such observations! The booster for sending Phobos-Soil to the orbit will be Fregat. This booster has been already used for launching several satellites into orbit before, though in Soyuz-Fregat configuration. (Phobos-Soil will be launched by Zenit-Fregat combo). There are some modifications made to the "base" version of Fregat since that (Fregat-SB means "Fregat with detachable tanks"), but this is still a similar hardware. Wikipedia says Fregat booster was used for 18 successfull launches before, so chances are high someone on this list has observed it before in different conditions (I mean, sunlit or eclipsed). This is why I think the following questions are important: - Has anybody observed Fregat booster firings (engine burns) before during Soyuz-Fregat launches? Was the exhaust plume visible in the Earth's shadow? If yes, what was its visual magnitude then? - If anybody has seen Fregat booster both before and after engine firing, what was the difference in magnitude? The answer to this questions will at least allow to estimate what equipment will be necessary for the observations of booster in Earth shadow. There's a lot of difference between naked-eye object and binocular or telescopic visibility! To Ted: can you please estimate if the engine firing and cut-off can be both visible from the same observing site (at least on one of the two orbits)? Also, I suppose the plots posted here before (1eb_04.jpg and 2eb_01.jpg) need some explanations for the coloration used. This page: http://phobos.cosmos.ru/index.php?id=312&L=2 explains what the thin and bold black and red parts of trajectory actually mean. And finally, the direct link to the page with TLE would be nice to have: http://phobos.cosmos.ru/index.php?id=1681&L=2 Best regards, Denis in Moscow _______________________________________________ Seesat-l mailing list http://mailman.satobs.org/mailman/listinfo/seesat-l
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