chongo's Journal: 2003-CR20 asteroid update for 2003-Feb-24 21:00 UTC

The 2003-CR20 asteroid remains at the top position in the current impact risks , and continues to become a higher risk object. The 2003-CR20 asteroid is the 2nd object on the list with a non-zero Torino impact hazard scale value.

New observations bring the observation total to 73 over a period of almost 12.5 days. 12.5 days is a bit short to create an extremely accurate model, but the model is getting better as time goes on.

Over the next few weeks the asteroid will be observable by large telescopes. A number of observatories have responded to the priority call for more observations. We expect that more observational data will allow us to improve the orbit model.

Based on the new observations, we calculate the following information for 2003-CR20:

• Diameter: 560m (same value)
• Mass: 2.4e11 kg (same value)
• Potential impact speed 24.87 km/sec (down from 24.88 km/sec)
• Potential impact energy (only IF it hits): 18,000 Megatons (same value)
• Torino impact hazard scale : 1 (same value)
• cumulative Palermo Scale : -1.14 (up from -1.17)
• close Earth approach paths in next 100 yrs: 15 (down from 19)
• Earth impact odds in the next 100 yrs: 1 in 23,000 (up from 1 in 27,000)

IF 2003-CR20 were to hit the Earth on land, its impact would result in sub-continent scale devastation. IF 2003-CR20 were to hit the Earth in the ocean, it would create a tsunami the size and speed of which have not been seen in recorded history. Such a tsunami would would inflict total devastation along adjoining coastlines and in some cases spread destruction far inland.

The impact speed, IF 2003-CR20 hits the Earth remains on the higher end of the typical asteroid approach speed.

The impact odds, while low, have become somewhat worse. Even though the number of Earth approaches have dropped significantly with the current model, these that remain yield a slightly greater risk of Earth impact. Still, there is a 99.9957% chance the asteroid will miss the Earth.

The following is a table of the close Earth approaches by 2003-CR20 where Earth lies within the 5-sigma path. See my explination for the data in this table. The 5-sigma approaches as of the time of this Journal entry are:

1. 2031-03-18.05 0.52 +/-0.137 (Earth inside 4-sigma path)
2. 2031-09-20.54 0.24 +/-0.900 (Earth inside 1-sigma path)
3. 2034-03-17.73 0.80 +/-0.168 (Earth inside 5-sigma path)
4. 2034-09-20.19 0.23 +/-0.912 (Earth inside 1-sigma path)
5. 2040-09-19.39 1.54 +/-0.876 (Earth inside 2-sigma path)
6. 2043-09-20.20 0.12 +/-0.884 (Earth inside 1-sigma path)
7. 2046-03-17.53 0.85 +/-0.19 (Earth inside 5-sigma path)
8. 2050-03-15.57 0.44 +/-0.114 (Earth inside 4-sigma path)
9. 2052-09-18.83 0.34 +/-0.871 (Earth inside 1-sigma path)
10. 2061-03-16.75 0.28 +/-0.0984 (Earth inside 3-sigma path)

The most significant close approaches have been marked in bold.

The highest risk approaches are 2046-03-17.53 0.85 +/-0.19 and the 2061-03-16.75 0.28 +/-0.0984 approach. There is a 1 in 56,000 chance and a 1 in 100,000 change respectively that 2003-CR20 will impact the Earth on that pass. There is a 99.9982% and 99.9990% chance that 2003-CR20 will miss the Earth on that pass as well.

The 2003-CR20 orbit model has become slightly worse for Earth. As the model continues to be refined, some other previous 5-sigma approaches have dropped off the list. However a number those that remain have been changing less and less as more observational data comes in. This type of refinement suggests that the model is on the way to becoming fairly accurate over the next 75 or so years.

So far, a search for an historic image of 2003-CR20 as failed to find anything. For most telescopes the asteroid would only show up in an photographic image during periods of time when the asteroid was within a few 0.1AU (Earth-Sun distances) or Earth. The historic image search continues.

We have been running the model backward in an effort to try and learn if this high risk orbit is a long standing or recent phenomenon. The backward model suggests that 2003-CR20 made a approach to Earth as recently as 2000-03-19.044 and 1997-03-08.086 of 10.7 million km and 5.9 million km respectively. But those not-so-close approaches would not have had a significant impact on the asteroid's orbit.

To complicate the model even further, 2003-CR20 may have a close encounter with Venus on 2097-11-12.28 when it comes within 2.57 million km of the planet. We are exploring the possibility that an encounter with Venus in the recent past may have shifted 2003-CR20 into its current orbit pattern.

Continue to stay tuned ...

P.S. There is no change is status for 1997-XR2. That asteroid remains as the only other non-zero Torino impact hazard scale object.