Ge/Ay133 What can the asteroid belt tell us about the early S.S.? 433 Eros ? Phobos Ge/Ay133

These types are not strongly separated, radially.

Comets are icy bodies that sublimate and become active when close to the Sun. They are believed to originate in two cold reservoirs beyond the orbit of Neptune: the Kuiper Belt (equilibrium temperatures of ~40 kelvin) and the Oort Cloud (~ 10 kelvin). We present optical data showing the existence of a population of comets originating in a third reservoir: the main asteroid belt. The main-belt comets are unlike the Kuiper Belt and Oort Cloud comets in that they likely formed where they currently reside and may be collisionally activated. The existence of the main-belt comets lends new support to the idea that main-belt objects could be a major source of terrestrial water. See also http://www.ifa.hawaii.edu/~hsieh/mbcs.html

Asteroid Itokawa as imaged by the Hayabusa probe. http://www.isas.jaxa.jp/e/snews/2005/1102.shtml

Collisions II

How do we measure rotation states? Lightcurves (lots of objects) Radar measurements (NEOs) Spacecraft exploration Toutatis Radar Image

What do simulations tell us about the asteroid belt? Hard to generate observed properties with just Jupiter & planetesimals or single large core, need mixture: Jupiter inserted at 10 Myr

Radial mixing extends over several 0.1 AU May help explain the spatial overlap of the various types? What about the large fraction of bodies that are strongly scattered?

Might the primordial disk have been more extensive? May help explain the spatial overlap of the various types? What about the large fraction of bodies that are strongly scattered?

Are even more extreme scenarios possible? The “Grand Tack” scenario… … which attempts to examine the impact of extensive migration.

Are even more extreme scenarios possible? Predicts extensive injection of “outer” planetesimals at >2 AU. And a low mass for Mars.

What determines the water content of the inner S.S.?

D/H ratios argue that Oort cloud comets did not deliver the bulk of the water…

Suppose there is an initial snow line… What happens?

In such a story, the orbital properties of Jupiter are critical…

What sort of systems emerge? Hierachical (most mass added in large collisions), so great variety, both in orbital properties… … and ultimate water content.

Question for later: What determines whether a planet is “habitable”? How much can the water vary? What is the maximum eccentricity for which liquid water can be maintained over several AE?