3.6/12 cm radio observation of Jupiter during the impact by Comet SL-9

We present 3.6/12 cm dual-frequency radio continuum observations of Jupiter with the Shanghai Observatory 25 m radio telescope during the impact by comet SL-9. There was no appreciable variation in the daily average flux density at 3.6 cm wavelength, but a relative increase of about 20% at 12 cm was observed during the impact.     

Earth impact probability of the Asteroid (25143) Itokawa to be sampled by the spacecraft Hayabusa

The Japanese spacecraft Hayabusa is planed to reach the Asteroid Itokawa in September 2005, and to bring back some samples of its surface to Earth in 2007. We have studied the future possible evolution of this asteroid by integrating numerically over 100 Myr a set of 39 initially indistinguishable orbits (clones), obtained either by small variations of the nominal initial conditions, or by using different computers (introducing different round-off errors). The results indicate that an Earth impact of this 500-m-size asteroid is likely within a million years, which is only a factor of four larger than the average impact frequency of asteroids of this size. The mission Hayabusa may thus sample a good candidate for being among the next 500-m-size Earth impactors.