Howdy All, I would think that solar sails would always be on topic here, but anyone on this list is likely to catch a real gaff in the article mentioned. Did you see it? I discovered that the error was culled verbatim from Wiki (thought that was plagiarism), and I corrected the Wiki article. I then wrote editor Dr. Phillips the following, though he's yet to make the correction... >It would be a good trick if something in low orbit could shine a >spot on Europe that would move at only 8 km/hour (take one heckuva >load of fuel!). I just corrected the text that Dauna copied >verbatim from Wikipedia. Please correct the error on your web >site. As the editor, you should have caught this mistake! Revealing an incredible ignorance for someone with a doctorate working for NASA, he actually wrote back with... >>Actually, a tumbling mirror in low Earth orbit could shine a spot >>at low velocity on the ground below *if* the mirror's rotation spun >>the beam opposite the instantaneous velocity of the spacecraft. >>It's unlikely, but possible. Anyway, if we're wrong, do you know >>the correct answer? How fast was the beam observed to travel >>across the ground? ...to which I responded... >Actually, Tony, it's just not possible, considering the speed of the >spacecraft, which is about 8 km/sec. The error is obvious. OK, it >might reflect a spot that would only move 8 km/hr by carefully >positioning the reflective surface as it passed over, but it would >only be able to do that for a couple/few minutes. Like any LEO, it >would come and go from your view on the ground in that short of a >time. Whoever wrote the Wiki article that your author copied simply >confused his units (km/hr for km/sec). I would hope that anyone on this list would agree with my analysis, and the above exchange validates this list and the information it disseminates. It's a shame this author and editor aren't members! Clear Skies and Best Regards to All, Art Cordova WV 38.067N, 80.434W, 2950' Elevation >From: "Robert Holdsworth" <robbonz1@xtra.co.nz> >To: "Seesat List" <SeeSat-L@satobs.org> >Subject: NASA article on history of solar sails > >This article will probably be of interest to many list members. > >http://science.nasa.gov/headlines/y2008/31jul_solarsails.htm?list1099069 > > >Probably OT for now but hopefully in the future they will be back on >our observation list. ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
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