Selected notes from NASA Media Advisory on 2008 TC3 (including comments from the question and answer session, notes: these are quick and limited notes and not meant to be a complete transcript, any errors are my own):
Panelists:
- Peter Jenniskens, meteor astronomer at NASA's Ames Research Center, Moffett Field, Calif., and the SETI Institute in Mountain View, Calif.
- Steve Chesley, scientist in NASA's Near-Earth Object Program Office at NASA's Jet Propulsion Laboratory in Pasadena, Calif.
- Michael Zolensky, cosmic mineralogist at NASA's Johnson Space Center in Houston
- Lucy McFadden, professor of astronomy at the University of Maryland in College Park
Peter Jenniskens:
Large effort from Muawia Shaddad of the University of Khartoum, Sudan and his students to recover sample, 2008 Tc3 meteorite from 2008 TC3 is named after Station 6, Arabic name, NASA is finding 15 NEAs per month. On Oct. 5 2008: Catalina Sky Survey finds object, impact would be 20 hours later, 2008 TC3 is of a very rare calls F-class, in the past the orbit was more eccentric, 9998 which is also an F-type could originate from the same debris field, Mohammed Alameen was one of the key students who was very helpful in finding the asteroid, biggest sample size obtained was 280 grams, asteroid of about this size hit the Earth about once a year, F-type asteroid are very rare – of all the asteroids (1.3% are F-class) – maybe because they are so dark (some observational bias perhaps), after second search in December, large fragments found south of trajectory, wonder if spread out widely just south of track, went back to Sudan with 52 people – vertical scan of trajectory, end of that search found 280 meteorites, total mass is 5 kg, tiny fraction of overall, actual recovery is a little south of trajectory
Steve Chesley:
Steve Chesley got phone call 8 hours prior to impact from Minor Planet Center, saw impact probability at 100% on screen, plotted and found impact location less than 9 hours to impact, dozens of observatories then observed and reported tracking measurements, last pre-impact prediction was about 1 km off in position and a coupled of seconds off (in terms of impact time) which is very good, impact energy over 1000 tons of TNT, figured that was the end of the story, several weeks later got a request from Peter Jenniskens about impact and trying to find it, spin measurements for objects this small not normally known (have an estimate for this object), meteorites do not alter that much when entering the atmosphere, most meteorites are relatively unchanged, different this time, probably know which asteroid this may have come from, normally difficult to connect spectra of meteorites and then asteroids – can now do that (first time), “first step to a Rosetta stone of asteroids”
Michael Zolensky:
Received samples from Peter for analysis, analysis group included NASA JSC, NASA Ames, Fordam University, and Carnegie Institution, meteor belongs to a rare group, novel properties not found in other meteorites dark areas are large pores lined with iron-magnesium silicon grains, due to volcanic properties, Carbonaceous materials, images 3c very porous, up to 40% porosity, must have been more porous still prior to impact, could have been in a single piece of a larger asteroid from long ago, this type of F-type normally contains Carbonaceous chondrites, could be related to CC (c-class asteroid), Ureilite type asteroid, nanometer sized diamonds in there, chunks of large graphite in there, possibility of mixing of different types of materials – happening at original large parent body, asteroids like planets 4.5 billion years ago, very hot and then cooled off
Lucy McFadden:
There may be more F-type asteroids since they are very dark, many larger bodies in the asteroid belt 4.5 billion years ago, smaller fragments formed over time from collisions, learned that there may be many more planets than today, many more larger bodies before, would call the hundred to a thousand kilometers of size of parent body, signature of 2008 TC3 indicates it came from such a body
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