{"id":39716,"date":"2011-09-25T15:48:29","date_gmt":"2011-09-25T15:48:29","guid":{"rendered":"http:\/\/euvolution.com\/futurist-transhuman-news-blog\/update-satellite-might-fall-on-friday-at-2200-utc-9-hours-bad-astronomy\/"},"modified":"2011-09-25T15:48:29","modified_gmt":"2011-09-25T15:48:29","slug":"update-satellite-might-fall-on-friday-at-2200-utc-9-hours-bad-astronomy","status":"publish","type":"post","link":"https:\/\/www.euvolution.com\/futurist-transhuman-news-blog\/astronomy\/update-satellite-might-fall-on-friday-at-2200-utc-9-hours-bad-astronomy.php","title":{"rendered":"Update: satellite *might* fall on Friday at 22:00 UTC +\/- 9 hours | Bad Astronomy"},"content":{"rendered":"

NASA’s UARS satellite<\/a> will almost certainly plunge back to Earth sometime Friday, September 23. The exact time is still not known, but the window for re-entry is centered at 22:00 UTC (6:00 p.m. Eastern US time) with a 9 hour uncertainty on either side. The Center for Orbital and Reentry Debris Studies<\/a> puts the satellite off the west coast of South America at that time:<\/p>

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However, this is still very preliminary!<\/strong> In other words, if you live in that area, don’t panic (in fact, odds are you shouldn’t panic at all<\/a>). The uncertainty is still pretty big, because it’s very difficult to pin down just when and where a satellite will come down. The +\/- 9 hour window is a pretty clear indication of that. Atmospheric conditions play a big role, as does the fact that the satellite is tumbling; that means the amount of drag from our air that it feels as it orbits changes constantly, making the exact moment of re-entry too hard to determine this far out. As time goes on, it’ll get more precise.<\/p>

The map shows several things. At the currently predicted re-entry time, the satellite is just west of Peru. The orange circle around it marks the area where re-entry would be visible. The blue track is the orbital position of the satellite over the Earth before<\/em> the predicted re-entry, and the yellow after it; both are marked with tick marks at 5-minute intervals. The track moves across the Earth because the Earth is rotating under the satellite! That changes the apparent ground track. The white line marks the day-night boundary, so it’ll be late afternoon locally at the predicted re-entry location.<\/p>

As of 07:00 Eastern US time, NASA was reporting<\/a> UARS’s orbit being slightly elliptical at 185 x 195 km (115 x 120 miles). That’s very low, as you’d expect for a satellite about to come down. NASA has provided an RSS feed for updates<\/a> if you want to stay on top of this, but I’ll note the CORDS site appears to be more current. They also have a nice discussion<\/a> of how and why satellites come back down.<\/p>

I’ll update this post as I hear news, but if there’s a significant change in the time or status, I’ll put up a new post.<\/p>

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NASA’s UARS satellite will almost certainly plunge back to Earth sometime Friday, September 23. The exact time is still not known, but the window for re-entry is centered at 22:00 UTC (6:00 p.m. Eastern US time) with a 9 hour … Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"limit_modified_date":"","last_modified_date":"","_lmt_disableupdate":"","_lmt_disable":"","footnotes":""},"categories":[21],"tags":[],"class_list":["post-39716","post","type-post","status-publish","format-standard","hentry","category-astronomy"],"modified_by":null,"_links":{"self":[{"href":"https:\/\/www.euvolution.com\/futurist-transhuman-news-blog\/wp-json\/wp\/v2\/posts\/39716"}],"collection":[{"href":"https:\/\/www.euvolution.com\/futurist-transhuman-news-blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.euvolution.com\/futurist-transhuman-news-blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.euvolution.com\/futurist-transhuman-news-blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.euvolution.com\/futurist-transhuman-news-blog\/wp-json\/wp\/v2\/comments?post=39716"}],"version-history":[{"count":0,"href":"https:\/\/www.euvolution.com\/futurist-transhuman-news-blog\/wp-json\/wp\/v2\/posts\/39716\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.euvolution.com\/futurist-transhuman-news-blog\/wp-json\/wp\/v2\/media?parent=39716"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.euvolution.com\/futurist-transhuman-news-blog\/wp-json\/wp\/v2\/categories?post=39716"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.euvolution.com\/futurist-transhuman-news-blog\/wp-json\/wp\/v2\/tags?post=39716"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}