News reports state that Russian astronomer, Professor Leonid Sokolov of St. Petersburg State University, predicted that Apophis would pass through the gravitational keyhole on its pass in 2029. He did state the possibility of this occurring but later stated the odds are small. If the asteroid passes through the gravitational keyhole it would deflect the asteroid just enough cause an impact in 2036, when Apophis returns.
http://www.physorg.com/news/2011-02-asteroid-deflection.html
NASA Current Projection of Apophis in 2029
http://www.universetoday.com/42246/apophis-odds-of-earth-impact-downgraded/
Apophis
DJ Tholen http://www.ifa.hawaii.edu/faculty/tholen/
R. A. Tucker, D. J. Tholen and F. Bernardi at Kitt Peak discovered Apophis June 24, 2004. The physical parameters of Apophis include a diameter of 0.270 km, mass of 2.7e+10 kg, and an impact velocity of 12.59 km/s (http://neo.jpl.nasa.gov/risk/a99942.html). The sheer mass and velocity of Apophis makes it an object of note because it has the capacity to create catastrophic damage and up to 10,000,000 deaths depending on the impact location. http://www.myfoxphilly.com/dpps/news/offbeat/russian-scientists-claim-asteroid-may-hit-earth-in-2036-dpgonc-20110210-fc_11818569
The controversy and difference in Russian and American projections regard the gravitational keyhole. The gravitational keyhole is a section of space in which an object moving through will have its course altered resulting in a collision on the next pass. The keyhole is generally very small and for Apophis is approximately half a mile, 18,893 miles from the Earth. The gravitational keyhole is within the range of uncertainty for Apophis during its 2029 flyby. (http://www.popularmechanics.com/science/space/deep/4201569?page=2)
Currently NASA projects the likelihood of an impact in 2036 as 4.3E-06 while Russian scientists project the odds to be much higher. Currently the Russian government is looking into plans to deflect the asteroid. You can see a projection of Apophis orbit for any day including April 13, 2036 (Easter Sunday) the possible collision time. http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=99942%20Apophis;orb=1;cov=0;log=0;cad=0#orb
Finding NEO (near Earth objects) relies on citizen scientist but in a very different way then the Zooniverse Project. The Zooniverse projects rely on the public for interpretation not collection of data while discovering asteroids is still requires active collection of data from amateur astronomers. The danger in having large amounts of data accessible to the general public with regards to NEO’s is the sensationalist journalism that results. Apophis makes headlines because there is a 4.3E-06 chance that it may strike the Earth and kill ten million people whereas about 42,000 people die per year in the US alone in car crashes. The story should instead read “There is a statistically insignificant chance that an Asteroid will hit Earth and kill 10,000,000 people meanwhile 1,000,000 people are sure to die in car crashes in the same time frame.
Hopefully if we ever do discover an asteroid on a collision course with Earth we won't have to rely on these guys to save us all.
A keyhole of half a mile is just to close for comfort especially when we are calculating the great distances of space. If it misses us in the year 2029, we may need to set things in motion now because once it passes us and we do nothing, it may not miss us the next time.
ReplyDeleteI don't know much about NEOs.. never gave 'em much thought, actually... but I do remember the movie reference! It raised some good questions...
ReplyDeleteI especially liked the link it drew between roughnecks and astronauts... (I was working in the oil/gas industry at the time while living near NASA with several friends/neighbors who worked on/for the space station project!)
Oh, .... and it had a phenomenal soundtrack!
If getting hit by an asteroid in 2036 sounds like a bad experience, then it may be somewhat comforting to know that 4.36E-06 is only slightly more probable than the 1 in 2-million chance we have of being struck by lightning.
ReplyDeleteGreat post - one always has to take care when reading sensationalist stories, as inevitably the 'worst case scenario' gets highlighted and the likely outcome hidden.
ReplyDeleteA gravitational keyhole of half a mile seems large, but should be put in context: basically, it means the asteroid has to pass in a region of space between 18,193.25 miles from the Earth and 18,892.75 miles from Earth, the odds of which, as highlighted in this post, are rather slim (in fact, they are less than the odds of you getting hit by a soccer-ball sized meteorite on the head!).
However, it does make sense for NASA and similar agencies to plan at least tentative investigations into what to do to deflect an asteroid. As the post says, there are counless NEOs out there, many of which remain to be detected.
No need to worry yet, though...