tag:blogger.com,1999:blog-8565737623121795004.post8102083280695032097..comments2023-11-29T13:13:23.022+00:00Comments on newgate news: Contains moderate perilMacheathhttp://www.blogger.com/profile/04451439759398780345noreply@blogger.comBlogger6125tag:blogger.com,1999:blog-8565737623121795004.post-69293868659072797142013-12-12T20:00:15.585+00:002013-12-12T20:00:15.585+00:002013 XY8 will be zipping past a mere 750,000-odd k...2013 XY8 will be zipping past a mere 750,000-odd km away later today - or two lunar distances<br /><br />Damn - missed it!James Highamhttps://www.blogger.com/profile/14525082702330365464noreply@blogger.comtag:blogger.com,1999:blog-8565737623121795004.post-30378679752730128932013-12-12T14:44:00.560+00:002013-12-12T14:44:00.560+00:00We are all doomed, eventually.We are all doomed, eventually.Demetriushttps://www.blogger.com/profile/17198549581667363991noreply@blogger.comtag:blogger.com,1999:blog-8565737623121795004.post-14660194120553912942013-12-11T16:26:37.114+00:002013-12-11T16:26:37.114+00:00R, as long as these chaps are on the ball, there s...R, as long as these chaps are on the ball, there should be some indication in advance:<br /><br />http://volcanoes.usgs.gov/<br /><br />though, slightly worryingly, their Yelowstone page is only updated once a week and, if the <a href="http://www.bbc.co.uk/sn/tvradio/programmes/supervolcano/programme.shtml" rel="nofollow">BBC drama-documentary*</a> is anything to go by, their field geologists will be the first to go (while making impossibly heroic attempts to escape). <br /><br />*There's even a <a href="http://www.bbc.co.uk/sn/tvradio/programmes/supervolcano/flash/supervolcano.shtml" rel="nofollow">play-along version</a><br /><br />...and, in any case, I'm sure Demetrius is keeping an eye open on our behalf.Macheathhttps://www.blogger.com/profile/04451439759398780345noreply@blogger.comtag:blogger.com,1999:blog-8565737623121795004.post-88550859593325242032013-12-11T16:10:21.977+00:002013-12-11T16:10:21.977+00:00"I promise I'll post on it the minute I h..."I promise I'll post on it the minute I hear of something happening there."<br /><br />You won't have to, we'll all be dead.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-8565737623121795004.post-80387307131793112502013-12-11T15:34:48.927+00:002013-12-11T15:34:48.927+00:00NS, my thanks for yet another comment considerably...NS, my thanks for yet another comment considerably more detailed and interesting than the original post.<br /><br />The question of threshold effectively adds up to a massive game of 'chicken', I suppose; the longer we wait, the more we know about the threat but the less time we have to tackle it.<br /><br />It does raise the question, though of whether we have - or will have 80 years hence - the ability to perform a minor deflection and steer small meteorites into uninhabited areas of the globe, and whether that would be more cost-effective than deep-space intervention.Macheathhttps://www.blogger.com/profile/04451439759398780345noreply@blogger.comtag:blogger.com,1999:blog-8565737623121795004.post-83832335458300076102013-12-11T13:43:54.387+00:002013-12-11T13:43:54.387+00:00I am with you entirely that we should be more conc...I am with you entirely that we should be more concerned about asteroid impact. This is something we can do something about, given enough time, thought and investment.<br /><br />This latest report, however, raises an interesting question. The NASA NEO Programme website reports it will have a total impact energy of around 2.3 megatons (Mt, TNT equivalent, so approx 9.7x10^15 Joules). In the grand scale of things, this is not a lot; it's about 150 to 200 times the energy in each of the Hiroshima and Nagasaki atomic bombs (which were carefully targetted to have maximum effect and released all their energy near instantaneously over the selected target(s)). It is about one tenth of the <a href="http://en.wikipedia.org/wiki/2004_Indian_Ocean_Earthquake#Energy_released" rel="nofollow">'surface rupture energy'</a> of the 2004 Indian Ocean earthquake.<br /><br />Other interesting comparisons include: (i) The Tunguska event: asteroid or comet impact in Russia in 1908, with estimated energy of 10 to 15Mt; (ii) The Chelyabinsk meteor: air burst over Russia in February 2013, with an estimated energy of 0.5Mt.<br /><br />So the interesting question is: what is the asteroid energy threshold at which it is worth deflecting it, as distinct from other protective measures such as evacuation (assuming one has time after predicting the likely arc of 'impact'), or investing the one-off cost (as distinct from the development cost that is shareable) in something else likely to offer better cost-benefit.<br /><br />There is an opinion on this, stated as from NASA, <a href="http://en.wikipedia.org/wiki/Potentially_hazardous_asteroid#Overview" rel="nofollow">recorded in Wikipedia</a>, which puts the 'dangerous' diameter as in excess of 100m to 150m. So 2013 XY8 does not make that threat level. However, it would likely be devastating over a modest area.<br /><br />Also interesting is how to measure the mass (which unfortunately drops out of the orbit calculations). Albedo (primarily sunlight reflection) is the usual method, but this is very approximate.<br /><br />Detection in advance also is problematic, with several modest sized impacts every year with no or negligible advanced notice. I wonder what is the current political cost-benefit analysis that is holding back further investment: eg chasing, 'catching up with' and observing an asteroid on near Earth fly-by? This seems to me to be an obvious step in almost all deflection strategies.<br /><br />Best regardsAnonymousnoreply@blogger.com