If I am interested in a sample return mission to Ceres using a similar propulsion technology package to Dawn, what kinds of additional propulsion would be required to land and then return?
Calculations in [1] and [2] yield that to achieve $v_{esc}$ you require 503m/s, and to achieve $v_{circ}$ 356m/s. Given the free rotation at the equator of 94m/s you need a $\Delta$V of 410m/s for $v_{esc}$ or 262m/s for $v_{circ}$.
My question is: aside from the large amounts of extra fuel for the return journey, what propulsion systems would be appropriate to make up this additional $\Delta$V. I would have thought that it is the initial 262m/s to achieve $v_{circ}$ that is prohibitive, as once orbiting you can continue using ion thrusters until $v_{esc}$ is achieved. So, what kinds of technology are appropriate for that range.
Dawns wet mass was ~1300kg and as $g_{ceres}=0.285m/s$ so thrust required to overcome gravity is 370N (although this would scale due to higher propellant and extra propulsion system requirements).
For asteroid mining, it seems to me that a combination of efficient ion engines with an additional propulsion system to achieve $v_{esc}$ is required.
[2] Could a Human reach escape velocity by jumping from the surface of Ceres (a dwarf planet)?