The NEAR Challenge Update

The Near-Earth Asteroid Rendezvous (NEAR) spacecraft will arrive at Earth-approaching asteroid Eros next month, in early January 1999. As of this writing, no mainstream astronomer has been willing to accept a wager against this prediction, although none expect it to be correct either.

Preamble: The exploded planet hypothesis (as described in Dark Matter, Missing Planets and New Comets) implies that all asteroids and comets are formed as debris clouds during the explosion of planet or moon-sized bodies at astronomically recent epochs. Only those asteroids involved in collisions will have their orbiting debris removed, forming families (in the case of long-ago collisions) or jet streams (in the case of recent collisions). For most "loner" asteroids and comets, the original debris clouds around the primary nucleus should still be intact. The debris would consist of material of all sizes from dust to near-primary-nucleus size. Normal evolution of such debris clouds under tidal forces would tend to concentrate much of the debris into the orbital plane, and to collect some of that planar debris in an equatorial ring at the synchronous satellite orbit location (typically 1-2 radii above the asteroid surface). Debris inside the synchronous orbit should be cleared out by tidal forces and mostly found now lying on the surface of the primary asteroid. These would commonly be seen at places of maximum radius on the primary nucleus, and often accompanied by roll marks because of their gentle, tangential impacts.

As this model pertains to the Eros encounter, the NEAR spacecraft will enter orbit around Eros in January 1999. The exploded planet hypothesis makes a specific prediction for the encounter that is unlikely to be true if the hypothesis is false. This assumes only that there is no relevant equipment malfunction or other mission failure, such as failure to achieve orbit around Eros. In particular, the model implies a considerable hazard for a spacecraft flying too close to an asteroid nucleus. Any "sudden, unexplained loss of spacecraft signal" while the spacecraft is flying deep inside the gravitational sphere of influence of Eros would be fully in accord with expectations of this model. Such an event cannot be declared a failure of this prediction if it happens before the spacecraft has had the opportunity to photograph at least the complete synchronous orbit space near Eros from sufficiently close range to be able to see small moons.

Specific Prediction: The NEAR spacecraft will discover three or more satellites 1-meter in size or larger in stable orbits around the Eros primary nucleus.

Postamble: We really expect many satellites ranging up to a few kilometers in size, a ring of material in the synchronous orbit, and a concentration of small particles in the orbital plane. But one must be specific in a prediction; and three or more satellites a meter or more in size should distinguish the exploded planet hypothesis (eph) prediction from the standard model because satellites arising from collisional processes are exceedingly rare. (Collisions normally cannot place ejecta in orbit because any such orbit intersects the crater from which it formed. Even if a low orbit were achieved, it would be inside the synchronous orbit, so tidal forces would bring it down again in a relatively short time.) Models other than the eph that predict satellites require special, rare circumstances, and seldom produce asteroids more complex than binary. In the eph, satellites are expected to be numerous and commonplace because every such body originates with dozens to thousands, and collisions have not had enough time since that origin to strip away most such debris clouds from "loner" (non-family) asteroids. With regard to the environment surrounding primary asteroid nuclei, what we find at Eros will therefore probably be representative of most "loner" asteroids -- either rich in satellites or for the most part devoid of them.