chongo's Journal: 09 Aug 2002 00:00 UTC update for the 1997-XR2 asteroid

The 1997-XR2 asteroid is currently the only object that as a Torino impact hazard scale value > 0.

1997-XR2 is ~230 meters (~755 feet) in diameter and has a mass of ~1.7e10 kg (~17,000,000 metric tons or ~18,800,000 non-metric tons). So it is much smaller than 2002-NT7.

If 1997-XR2 were to impact earth, it would come in at a rate of ~13.25 km/sec (~29,600 MPH). The force of such an impact would be equivalent to 360 megatons of TNT.

The next close approach of 1997-XR2 is in 1 June 2101 21:30 UTC. The odds of this close approach being an impact is 1 in ~22,000. This means there is a ~99.9955% chance that 1997-XR2 will MISS the earth.

The model suggests that 1997-XR2 could miss the earth by ~1720 km (~1070 miles) with a +/- ~213 km (~132 miles) margin of error.

The 1997-XR2 has a Torino scale of 1 (larger the number, the greater the hazard) and a Palermo scale of -2.71.

This model is based on some 144+ observations. Because the close approach is almost 100 years from now, it is at the extreme end of being considered usable for an accurate orbit model.

The 1997-XR2 is very dark/black and small making is difficult to observe except when it near the earth. Currently, only very sensitive telescopes can observe it. In Aug 2002, the 1997-XR2 asteroid was only ~23.5 magnitude in brightness. A 23.5 mag object is ~10,000,000 times fainter than what the eye can see and ~10,000 times fainter than Pluto.

In Aug 2002, 1997-XR2 was ~338,000,000 km (~210,000,000 miles) from Earth. The ping (radar) round-trip time from Earth (127.0.0.1 :-)) is ~37.6 minutes.

I will post an update to this journal if/when the 1997-XR2 model changes in a significant way.