  Exploration of extreme environments, including caves, canyons and cliffs on
low-gravity surfaces such as the Moon, Mars and asteroids can provide insight
into the geological history of the solar system, origins of water, life and
prospect for future habitation and resource exploitation. Current methods of
exploration utilize large rovers that are unsuitable for exploring these
extreme environments. In this work, we analyze the feasibility of small,
low-cost, reconfigurable multirobot systems to climb steep cliffs and canyon
walls. Each robot is a 30-cm sphere covered in microspines for gripping onto
rugged surfaces and attaches to several robots using a spring-tether. Even if
one robot were to slip and fall, the system would be held up with multiple
attachment points much like a professional alpine climber. We analyzed and
performed detailed simulations of the design configuration space to identify an
optimal system design that trades off climbing performance with risk of
falling. Our results identify a system of 4 robots is best suited when enabling
single-robot climbs, while a system of 6 robots are suited when two robots
climb simultaneously. The results show a pathway towards demonstration of the
system on real robots.
