[meteorite-list] 2011 EH a better match to Chelyabinsk than 2011 EO40

From: Matson, Robert D. <ROBERT.D.MATSON_at_meteoritecentral.com>
Date: Thu, 1 Aug 2013 12:03:49 -0700
Message-ID: <7C640E28081AEE4B952F008D1E913F1707FB2AD5_at_0461-its-exmb04.us.saic.com>

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-bounces at meteoritecentral.com
[mailto:meteorite-list-bounces at 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.
Received on Thu 01 Aug 2013 03:03:49 PM PDT