Seth A Jacobson

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Pairs of asteroids sharing similar heliocentric orbits, but not bound together, were found recently. Backward integrations of their orbits indicated that they separated gently with low relative velocities, but did not provide additional insight into their formation mechanism. A previously hypothesized rotational fission process may explain their(More)
According to the generally accepted scenario, the last giant impact on Earth formed the Moon and initiated the final phase of core formation by melting Earth's mantle. A key goal of geochemistry is to date this event, but different ages have been proposed. Some argue for an early Moon-forming event, approximately 30 million years (Myr) after the(More)
A solid corrosion-resistant torsional waveguide of diamond cross section has been developed to sense, online and in real-time, the characteristics of the liquid in which it is submerged. The sensor can measure, among other things, the liquid content of a bubbly medium, the density of adjacent pure liquids, the equivalent density of liquid-vapor mixtures or(More)
Earth and the Moon are shown here to have indistinguishable oxygen isotope ratios, with a difference in Δ'(17)O of -1 ± 5 parts per million (2 standard error). On the basis of these data and our new planet formation simulations that include a realistic model for primordial oxygen isotopic reservoirs, our results favor vigorous mixing during the giant impact(More)
We find that when a contact binary asteroid composed of two non-spherical components is spun to fission, its initial relative equilibrium state is always unstable. This implies that all fissioned binary asteroid systems should have an initial period of strongly unstable orbital and rotational evolution. The implication is that application of classical tidal(More)
Highly siderophile elements (HSEs) are strongly depleted in the bulk silicate Earth (BSE) but are present in near-chondritic relative abundances. The conventional explanation is that the HSEs were stripped from the mantle by the segregation of metal during core formation but were added back in near-chondritic proportions by late accretion, after core(More)
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