Hi Ron/List, Back in February, I found better orbital matches to the Chelyabinsk meteoroid than 2011 EO40. Using modified Drummond criterion, here were the top-10 minor planets with orbits most similar to Chelyabinsk:
Target elements (from Borovicka, et al. in IAU circular 3423): a=1.55 q=0.768 i=3.6 peri=109.7 Node=326.41 Mod. D Minor Planet a q e i Peri Node ------- ------------ ------- ------- ------- ------- -------- -------- 0.01747 2011 EH 1.47934 0.76097 0.48560 2.3500 96.5974 339.1767 0.03873 2003 BR47 1.62776 0.81357 0.50019 4.4207 112.4835 314.5904 0.04412 2000 SM10 1.66254 0.76480 0.53998 0.5485 176.6819 260.6116 0.05005 2005 CJ 1.74998 0.82960 0.52594 1.0837 81.6277 358.1088 0.05131 2010 TG54 1.67128 0.79423 0.52478 5.6661 72.3370 15.8961 0.05381 2011 EO40 1.65380 0.76015 0.54036 3.3638 17.0571 50.3097 0.05770 2005 EQ95 1.66868 0.78618 0.52886 2.3979 252.1175 196.2815 0.05854 2001 TB 1.71933 0.81500 0.52598 3.9657 245.0252 192.2105 0.06243 1998 OX4 1.58044 0.81241 0.48596 4.5135 117.0933 299.7249 0.06301 2004 RN251 1.65344 0.78141 0.52740 4.3904 245.9320 179.6023 As you can see, five asteroids are a better match that 2011 EO40. If instead I use Carlos de la Fuente Marcos's estimated Chelyabinsk elements: a=1.62 q=0.76 i=3.82 peri=109.44 Node=326.41 I get the following best matches: Mod. D Minor Planet a q e i Peri Node ------- ------------ ------- ------- ------- ------- -------- -------- 0.05261 2011 EH 1.47938 0.76102 0.48559 2.3499 96.6043 339.1740 0.06574 2000 SM10 1.66246 0.76473 0.54000 0.5486 176.6833 260.6156 0.08241 2008 DJ 1.98262 0.78599 0.60356 5.0512 117.8168 319.2589 0.08806 1999 NC43 1.75962 0.74039 0.57923 7.1231 120.5589 311.8189 0.09372 2005 CJ 1.74995 0.82956 0.52595 1.0836 81.6440 358.0967 0.09942 2011 SE58 1.89434 0.73636 0.61128 1.2107 70.4829 5.6749 0.10123 2003 BR47 1.62785 0.81354 0.50024 4.4205 112.4906 314.5859 0.10454 2004 CA2 2.11191 0.81587 0.61368 3.2561 130.5519 304.0696 0.11316 1997 TZ16 2.02107 0.81381 0.59734 3.7728 67.5599 13.5386 0.11659 2011 EO40 1.65381 0.76015 0.54036 3.3638 17.0559 50.3092 So there is some shuffling, but 2011 EO40 is an even worse match, and 2011 EH is still #1. I'll rerun the calculation later today against the most recent full catalog to see if any new candidates appear. --Rob -----Original Message----- From: meteorite-list-boun...@meteoritecentral.com [mailto:meteorite-list-boun...@meteoritecentral.com] On Behalf Of Ron Baalke Sent: Thursday, August 01, 2013 10:48 AM To: Meteorite Mailing List Subject: [meteorite-list] Asteroid Pinpointed As Likely Source ofChelyabinsk Meteor http://www.newscientist.com/article/dn23976-asteroid-pinpointed-as-likel y-source-of-russian-meteor.html Asteroid pinpointed as likely source of Russian meteor by Jacob Aron New Scientist 01 August 2013 Who's been taking potshots at Earth? A new study shows how a 200-metre-wide cluster of rocks, first spotted by scientists in 2011, could have spawned the Chelyabinsk meteor which exploded over Russia earlier this year. If correct, that means we may need to watch out for further impacts from other fragments of the cluster, which are still at large, in orbit around the sun. The meteor that exploded over Russia on 15 February, scattering debris across the Chelyabinsk region and injuring hundreds , came as a complete surprise. Since then researchers have traced it to the Apollo asteroid family, but no one had matched it to a particular member of the group. Now Carlos de la Fuente Marcos and his brother Raul, both of the Complutense University of Madrid, Spain, are pointing the finger at asteroid 2011 EO40. Roughly 200 metres wide, it is a rock - or cluster of rocks - previously listed as potentially hazardous by the International Astronomical Union's Minor Planet Center in Cambridge, Massachusetts. Rubble pile First the pair used a computer simulation to create hypothetical orbital paths around the sun that would have intersected with Earth at the time that the meteor hit. Then they searched a database of known asteroids for ones that could have produced rocks that follow those orbits . The closest match was with 2011 EO40. Most asteroids aren't solid rocks but rather rock clusters that have been gradually fragmenting for eons. "Most asteroids are rubble piles, very fragile," says Carlos. So the brothers also simulated the disintegration of an object the size of 2011 EO40 and showed that it could fragment to produce a Chelyabinsk-size object that would impact with Earth at the correct time. Future observations of 2011 EO40 could help confirm it as the Chelyabinsk parent. Analysing the light bouncing off it would let us match its composition to fragments of the meteorite collected in Russia. Sending a probe to bring back samples of the asteroid is the only way to be sure, but that is a hugely expensive mission that is unlikely to happen. "The cheap but not fully conclusive approach will have to suffice for the time being," says Carlos. Asteroid census If 2011 EO40 really is Chelyabinsk's parent, future observations should also help us predict if Chelyabinsk has any siblings still in orbit that might also pose a threat to Earth, says Carlos. "Having a precise census of this population can help us predict similar impacts in the future." Jorge Zuluaga of the University of Antioquia in Colombia, who traced the Chelyabinsk meteor to the Apollo asteroid family, cautions that EO40 2011 has yet to be confirmed as the parent. And even it is, he is not too worried about it spawning further impacts. "I don't think this particular asteroid is more hazardous than others in the MPC list," he says. He also points out that the asteroid itself isn't on a direct collision course with Earth, in any case. Meanwhile, other researchers are working to piece together the orbit of the Chelyabinsk meteor by different methods. One recent study by Simon Proud of the University of Copenhagen, Denmark, unearthed satellite pictures that show what the meteor looked like from space as it streaked through our atmosphere. ______________________________________________ Visit the Archives at http://www.meteorite-list-archives.com Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list