  Exploration of small bodies, namely comets and asteroids remain a challenging
endeavor due to their low gravity. The risk is so high that missions such as
Hayabusa II and OSIRIS-REx will be performing touch and go missions to obtain
samples. The next logical step is to perform longer-term mobility on the
surface of these asteroid. This can be accomplished by sending small landers of
a 1 kg or less with miniature propulsion systems that can just offset the force
of asteroid gravity. Such a propulsion system would ideally be used to hop on
the surface of the asteroid. Hopping has been found to be most efficient form
of mobility on low-gravity. Use of wheels for rolling presents substantial
challenges as the wheel can't gain traction to roll. The Asteroid Mobile Imager
and Geologic Observer (AMIGO) utilizes 1 kg landers that are stowed in a 1U
CubeSat configuration and deployed, releasing an inflatable that is 1 m in
diameter. The inflatable is attached to the top of the 1U lander, enabling high
speed communications and a means of easily tracking lander from an overhead
mothership. Milligravity propulsion is required for the AMIGO landers to
perform ballistic hops on the asteroid surface. The propulsion system is used
to navigate the lander across the surface of the asteroid under the extremely
low gravity while taking care to not exceed escape velocity.Although the
concept for AMIGO missions is to use multiple landers, the more surface area
evaluated by each lander the better. Without a propulsion system, each AMIGO
will have a limited range of observable area. The propulsion system also serves
as a rough attitude control system (ACS), as it enables pointing and regulation
over where the lander is positioned via an array of MEMS thrusters.
