tag:blogger.com,1999:blog-15164221.post7867245383356729453..comments2023-03-17T13:58:34.433+01:00Comments on SatTrackCam Leiden (b)log: [updated] HUGE fireball over Russia this morning! Not 2012 DA14 related.SatTrackCam Leidenhttp://www.blogger.com/profile/08711764306071043709noreply@blogger.comBlogger1125tag:blogger.com,1999:blog-15164221.post-45896515245155703812013-02-24T08:01:59.306+01:002013-02-24T08:01:59.306+01:00Thanks for the informative post. What I was wonder...Thanks for the informative post. What I was wondering about is whether the calculated trajectory for the Russian meteor was including the effects of Earth's gravity. I'm inclined to think it should not be included. To give the best view of what the true orbit of the meteor was, you should give it as if the Earth was not there to interrupt it and change its trajectory with its gravity.<br />On the other hand I was able to show using a Hohmann orbit calculator that using the delta-V you get from a close in Earth encounter, up to 11.2 km/s, can change a 2012 DA14 type orbit into the one claimed for the Russian meteor, with one big caveat. The Hohmann calculator assumes you get the delta-V boost all at once. So it's not precisely correct to apply it to a case when you get it from a gravitating body where it's applied over time.<br />Here's the calculator:<br /><br />Simple Hohmann Transfer Orbit Calculator.<br />http://web.archive.org/web/20100128043604/http://home.att.net/~ntdoug/smplhmn.html<br /><br />Select the orbit around the Sun and input a little less than 1 AU, say, 135,000,000 km, for the beginning orbit radius, which is that of 2012 DA14, and 2.5 AU, about 375,000,000 for the ending orbit radius, the aphelion for the Russian meteor. You'll see the delta-v needed to change the smaller orbit into an elliptical one with the larger, ending radius as its aphelion is well within that which can be delivered by the Earth's gravity. (Hohmann orbit changes use two delta-v burns. The first changes the original smaller, circular orbit into a larger elliptical one. The second circularizes this into one with that larger radius. For this application we only need it to have the elliptical shape of the Russian meteor's orbit so that first delta-v of the calculator is the only one I'm using.)<br /><br /> Bob ClarkRobert Clarkhttps://www.blogger.com/profile/16114043697010364282noreply@blogger.com