Donald B. Bickler was an American mechanical engineer at NASAâÂÂs Jet Propulsion Laboratory (JPL). He is best known for developing the rocker-bogie suspension system, a six-wheeled articulated mobility architecture first used for the Sojourner rover during NASAâÂÂs 1997 Mars Pathfinder mission and later adopted for subsequent Mars rovers. His career also included earlier work in solar energy engineering and later work in rover mobility, off-road traction analysis, and wheel technologies.
Bickler earned a Bachelor of Science degree in Mechanical Engineering from Northwestern University in 1956.
After graduating, Bickler worked in automotive and mechanical systems. While working at Stewart-Warner Corporation he was he was listed as an inventor on a U.S. patent for a gas carbureting apparatus.
By the early 1960s he was working in photovoltaic measurement and solar instrumentation. In 1963, he co-authored Solar Energy Measurement Techniques with Bernd Ross, describing measurement and calibration methods for solar cell performance in aerospace contexts. A 1967 patent lists him as an inventor of a solar radiation simulation apparatus for laboratory testing of photovoltaic devices (commonly referred to as a solar simulator).
Bickler joined NASAâÂÂs Jet Propulsion Laboratory in 1975. Over the course of more than four decades at JPL, he worked in mechanical engineering across both solar-energy technology and planetary rover mobility, and became associated in particular with the development of articulated suspension systems for Mars rovers. JPL later identified him as a principal engineer in Mechanical Engineering Section 352, while a 2012 JPL profile referred to him as leading the laboratoryâÂÂs Advanced Mechanical Systems team. In the later part of his career, he also focused on training and mentoring younger engineers.
JPL publications later noted both 30 years of service (as of 2005) and his retirement in October 2017 after 42 years at JPL.
During the late 1970s Bickler contributed to JPL solar-energy work associated with U.S. Department of Energy programs. He co-authored a DOE/JPL report summarizing an LSA Project technology development update presented at the 10th Project Integration Meeting (August 1978). In a 1979 JPL report on the SAMICS cost-analysis methodology, the author credited BicklerâÂÂs encouragement and insistence on rigorous analysis during early development as important to the methodologyâÂÂs applicability and validation.
By the late 1980s Bickler was involved in rover mobility studies at NASAâÂÂs Jet Propulsion Laboratory (JPL) during early mission planning for robotic Mars exploration. Contemporary reporting later described experimental rover prototypes developed at JPL using a six-wheel articulated mobility system created by Bickler.
During early rover mission studies Bickler began developing articulated mobility concepts for planetary rovers and constructed several early rover prototypes in his garage before the rover project had formal funding.
The earliest prototype was an articulated wooden rover model that demonstrated the stability and range of motion of a springless suspension capable of maintaining wheel contact while traversing obstacles larger than a wheel diameter.
Bickler subsequently developed a motorized experimental rover sometimes referred to as the âÂÂBickler pantographâÂÂ, which used parallel four-bar linkages to achieve high ground clearance and improved obstacle-traversal capability.
Later experimental rovers known as the Rocky series incorporated a rocker-bogie articulation system that retained the mobility advantages of the earlier designs while improving obstacle-climbing performance over previous six-wheel rover concepts developed at JPL.
BicklerâÂÂs suspension architecture was formalized in U.S. Patent 4,840,394, Articulated Suspension System, filed in 1987 and issued in 1989.
The articulated rocker-bogie suspension was adopted for the rover developed for NASAâÂÂs Mars Pathfinder mission. The design was first used for the Sojourner rover in 1997 and later formed the basis of mobility systems used on subsequent Mars rover missions.
BicklerâÂÂs work on rover mobility systems continued to shape later Mars missions; in 2012, JPL engineer Jaime Waydo described him as âÂÂthe father and inventor of Martian mobilityâÂÂ.
BicklerâÂÂs published work also included off-road traction analysis. In 1990 he authored an SAE technical paper describing a method for computing traction forces when all wheels of a vehicle are slipping under eccentric loading conditions.
He also co-authored a NASA Tech Brief describing all-metal tires intended for environments where elastomeric and pneumatic tires would not function (including extreme temperatures).