chongo's Journal: 2003-CR20 asteroid update for 2003-Feb-21 19:30 UTC

The 2003-CR20 asteroid has taken the top position in the current impact risks !!!

New observations bring the observation total to 23 over a period of almost 9 days. 9 days is a little short to create an extremely accurate model. However, these 23 observations are from observers/observatories with a good track record of accurate observations. They come from 7 independent observatories have provided data that fit well together. Taken as a whole, they allow one to begin to produce an accurate orbit model.

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

• Diameter: 450m (down from 520m)
• Mass: 1.3e11 kg (down from 1.9e11 kg)
• Impact speed (only IF it hits): 24.84 km/s (down from 24.95 km/sec)
• Torino impact hazard scale : 1 (up from 0)
• cumulative Palermo Scale : -1.73 (up from -1.86)
• close Earth approach paths in next 100 yrs: 34 (down from 234)
• Earth impact odds in the next 100 yrs: 1 in 63,000 (up from 1 in 233,000)

The 2003-CR20 asteroid is the 2nd object on the list with a non-zero Torino impact hazard scale value.

The refined size and mass, while slightly smaller, is still significant. 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 slightly worse. Even though the number of Earth approaches have dropped significantly with the current model, those 34 that remain yield a slightly greater risk of Earth impact. Still, there is a 99.9984% chance the asteroid will miss the Earth, so don't start ''heading for the hills'' (yet). :-)

The current model has a number of close approaches to Earth that require more careful processing. For example, in some cases we need to account for the non-uniform mass distribution of the Earth and the time of day of the close approach. This work is being performed as this journal entry is being written. If this work results in a significantly different orbit model, I will post a journal update on the revised model.

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 2003-Feb-21 19:30 UTC, are:

1. 2026-09-19.17 6.78 +/- 2.47 (Earth inside 3-sigma path)
2. 2029-09-18.88 6.87 +/- 2.56 (Earth inside 3-sigma path)
3. 2031-09-20.52 0.65 +/- 2.48 (Earth inside 1-sigma path)
4. 2032-09-18.47 6.22 +/- 2.49 (Earth inside 3-sigma path)
5. 2032-09-18.58 8.36 +/- 2.54 (Earth inside 4-sigma path)
6. 2034-09-20.08 3.93 +/- 2.37 (Earth inside 2-sigma path)
7. 2035-09-19.13 3.07 +/- 2.55 (Earth inside 2-sigma path)
8. 2043-09-20.48 7.43 +/- 2.44 (Earth inside 4-sigma path)
9. 2046-03-17.53 0.82 +/- 0.22 (Earth inside 4-sigma path)
10. 2048-09-19.27 0.01 +/- 2.15 (Earth inside 1-sigma path)
11. 2049-03-16.97 0.92 +/- 0.23 (Earth inside 4-sigma path)
12. 2050-03-15.57 0.09 +/- 0.32 (Earth inside 1-sigma path)
13. 2054-09-19.53 5.66 +/- 2.20 (Earth inside 3-sigma path)
14. 2055-09-20.03 4.49 +/- 2.39 (Earth inside 2-sigma path)
15. 2058-09-19.28 4.74 +/- 2.31 (Earth inside 2-sigma path)
16. 2061-09-18.79 0.48 +/- 2.24 (Earth inside 1-sigma path)
17. 2064-09-18.46 5.29 +/- 2.20 (Earth inside 3-sigma path)
18. 2065-09-18.65 2.33 +/- 2.26 (Earth inside 2-sigma path)
19. 2073-03-16.43 1.16 +/- 0.25 (Earth inside 5-sigma path)
20. 2083-09-19.14 0.23 +/- 2.23 (Earth inside 1-sigma path)

The most significant close approaches have been marked in bold.

Please keep in mind that even when the Earth is inside the 1-sigma path, the chance of impacting are NOT ~68%! One has to factor in the chance that the model path will be taken at all. For example, while the 2048-09-19.27 0.01 +/- 2.15 path may look bad for Earth, the overall probability that the Earth will be impacted on (or near) that date is only ~1 in 83,333,000. So even though that path looks like the Earth is right in the ''bull's eye'', there is still a 99.9999988% chance the asteroid will miss the Earth for that approach.

The highest risk approach is the 2046-03-17.53 0.82 +/- 0.22 approach. Even though the Earth is 4-sigma away, the chance that this given path will be taken is somewhat significant. So you cannot always tell high risk paths from the Earth target sigma. The odds of 2003-CR20 impacting on or near that date are only ~1 in 196,000 chance. Still there is a 99.99949% chance the asteroid will miss the Earth on or near that date.

You notice this entry has gone into a lot of detail about 2003-CR20, it is because the orbit models are getting worse not better as more observational data comes in. Still, it is possible that with the same quality level of observations over a longer period of time (than just 9 days) will change the model. Experience has shown that usually such model changes yields a model with a lower impact risk.

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.