  Wheeled planetary rovers such as the Mars Exploration Rovers (MERs) and Mars
Science Laboratory (MSL) have provided unprecedented, detailed images of the
Mars surface. However, these rovers are large and are of high-cost as they need
to carry sophisticated instruments and science laboratories. We propose the
development of low-cost planetary rovers that are the size and shape of
cantaloupes and that can be deployed from a larger rover. The rover named
SphereX is 2 kg in mass, is spherical, holonomic and contains a hopping
mechanism to jump over rugged terrain. A small low-cost rover complements a
larger rover, particularly to traverse rugged terrain or roll down a canyon,
cliff or crater to obtain images and science data. While it may be a one-way
journey for these small robots, they could be used tactically to obtain
high-reward science data. The robot is equipped with a pair of stereo cameras
to perform visual navigation and has room for a science payload. In this paper,
we analyze the design and development of a laboratory prototype. The results
show a promising pathway towards development of a field system.
