Italian astronomers upgrade possible asteroid hit on Earth

William Atkins
Wednesday, 18 February 2009 20:30

Science - Space

The team adds, “The probabilities accumulate to a total impact probability of approximately 10E-3, with a pair of closely related routes to impact in 2182 comprising more than half of the total. The analysis of impact possibilities so far in the future is strongly dependent on the action of the Yarkovsky effect, which raises new challenges in the careful assessment of longer term impact hazards.”

The Yarkovsky effect (which produces a Yarkovsky acceleration) is a force that acts on a rotating body in space (such as meteoroids and asteroids) that is caused by the momentum carried by photons of electromagnetic radiation (light).

The abstract continues, “Even for asteroids with very precisely determined orbits, a future close approach to Earth can scatter the possible trajectories to the point that the problem becomes like that of a newly discovered asteroid with a weakly determined orbit.”

“If the scattering takes place late enough so that the target plane uncertainty is dominated by Yarkovsky accelerations then the thermal properties of the asteroid, which are typically unknown, play a major role in the impact assessment. In contrast, if the strong planetary interaction takes place sooner, while the Yarkovsky dispersion is still relatively small compared to that derived from the measurements, then precise modeling of the nongravitational acceleration may be unnecessary.”

This latter statement says that the probability of impact between the asteroid and Earth is based on only roughly estimated physical properties of the asteroid, along with only an estimated amount of known change in the forward movement of the asteroid caused by these Yarkovsky photons.

Consequently, to more accurately assess the probability of impact of the asteroid with Earth, a more detailed model of the asteroid is necessary.

The authors say that to accomplish such a detailed map many more years of observations will be needed.

If Asteroid 1999 RQ₃₆ were to hit the Earth, its impact in the ocean (which is likely since Earth is covered mostly by water) would cause a gigantic tsunami, a large ocean wave, that would likely wreck havoc to nearby landmasses.

We have plenty of time to make further observations of this asteroid. Of course, it is never wise to wait until the last minute if indeed this asteroid should make contact with Earth over the next 160 to 190 years.