  It is likely that multiple bodies with masses between those of Mars and Earth
("planetary embryos") formed in the outer planetesimal disk of the solar
system. Some of these were likely scattered by the giant planets into orbits
with semi-major axes of hundreds of AU. Mutual torques between these embryos
may lift the perihelia of some of them beyond the orbit of Neptune, where they
are no longer perturbed by the giant planets so their semi-major axes are
frozen in place. We conduct N-body simulations of this process, and its effect
on smaller planetesimals in the region of the giant planets and the Kuiper
belt. We find that (i) there is a significant possibility that one sub-Earth
mass embryo, or possibly more, is still present in the outer solar system; (ii)
the orbit of the surviving embryo(s) typically has perihelion of 40--70 AU,
semi-major axis less than 200 AU, and inclination less than 30 degrees; (iii)
it is likely that any surviving embryos could be detected by current or planned
optical surveys or have a significant effect on solar-system ephemerides; (iv)
whether or not an embryo has survived to the present day, their dynamical
influence earlier in the history of the solar system can explain the properties
of the detached disk (defined in this paper as containing objects with
perihelia > 38 AU and semi-major axes between 80 and 500 AU).
