chongo's Journal: 29 July 2002 19:00 UTC update for the 2002-NT7 asteroid

We received some important new observations that have resulted in an important change to the 2002-NT7 orbit model, so I came back to publish this report.

The new model uses 118 observations spanning about 19 days, 16 hours.

Some good news:

The model's accuracy continues to improve. New observation data has eliminated a number of the model's previous close approaches:

The close appraoch list is now:

1. Feb 1, 2053 (distance ~18,600 km)
2. Feb 1, 2060 (distance ~17,699 km)
3. Feb 1, 2067 (distance ~26,200 km)

The Feb 1 2062 and Feb 1 2078 approaches are no longer considered by the model to be a hazard.

The Palermo scale is now -1.00 (was -0.89). However the Torino Scale remains at 1. (A value >0 means there is something to worry about). The main reason for the Palermo scale drop is that there are fewer close approaches to worry about over the next 75 years. Fewer close approaches means fewer risky events. Fewer risky events in the next 75 years results in a lower Palermo value.

The size estimate has been reduced from 2.03 km to 2.01 km.

Some not so good news:

The odds of impact are slightly worse. They were about 1 in ~3,300,000. The new model suggests that the odds of an impact in the next 75 years is about 1 in ~2,600,000. Most of this "odds drop" is due to reduced error within the model.

Comment summary:

IMHO, It is still the case that there is next to nil chance of impact before 2060. It is 2060 and beyond events that are of concern. It is the pattern of orbit adjustments at and beyond 2060 that may be of concern.

The drop of the Feb 1, 2078 approach is due in part a greater degree of uncertainty after 2075. The Feb 1, 2078 (and later close approaches) may make it back on the list as more observtion data comes in. On the other hand, more observation data may alter the model and eliminate these from the hazard catagory altogether.

The next model update may still be on/after Aug 5 ... or sooner if new data warrants and update.