  Wheeled ground robots are limited from exploring extreme environments such as
caves, lava tubes and skylights. Small robots that can utilize unconventional
mobility through hopping, flying or rolling can overcome these limitations.
Mul-tiple robots operating as a team offer significant benefits over a single
large ro-bot, as they are not prone to single-point failure, enable distributed
command and control and enable execution of tasks in parallel. These robots can
complement large rovers and landers, helping to explore inaccessible sites,
obtaining samples and for planning future exploration missions. Our robots, the
SphereX, are 3-kg in mass, spherical and contain computers equivalent to
current smartphones. They contain an array of guidance, navigation and control
sensors and electronics. SphereX contains room for a 1-kg science payload,
including for sample return. Our work in this field has recognized the need for
miniaturized chemical mobility systems that provide power and propulsion. Our
research explored the use of miniature rockets, including solid rockets,
bi-propellants including RP1/hydrogen-peroxide and
polyurethane/ammonium-perchlorate. These propulsion options provide maximum
flight times of 10 minutes on Mars. Flying, especially hovering consumes
significant fuel; hence, we have been developing our robots to perform
ballistic hops that enable the robots to travel efficiently over long
distances. Techniques are being developed to enable mid-course correction
during a ballistic hop. Using multiple cameras, it is possible to reconstitute
an image scene from motion blur. Hence our approach is to enable photo mapping
as the robots travel on a ballistic hop. The same images would also be used for
navigation and path planning. Using our proposed design approach, we are
developing low-cost methods for surface exploration of planetary bodies using a
network of small robots.
