​MAPLE: Wireless Power Transfer in Space

MAPLE, short for Microwave Array for Power-transfer Low-orbit Experiment and one of the three key experiments within SSPD-1, consists of an array of flexible lightweight microwave power transmitters driven by custom electronic chips that were built using low-cost silicon technologies. It uses the array of transmitters to beam the energy to desired locations. For SSPP to be feasible, energy transmission arrays will need to be lightweight to minimize the amount of fuel needed to send them to space, flexible so they can fold up into a package that can be transported in a rocket, and a low-cost technology overall.

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As announced in June 2023, MAPLE successfully demonstrated its capability to wirelessly transmit power in space and direct a beam to Earth, marking a significant milestone in the field. Following the initial demonstrations, MAPLE experiments continued for an additional eight months, during which the team pushed the system to its limits. This allowed them to identify potential weaknesses and gain insights that would inform future designs. By comparing the array’s performance early in the mission with its performance after being intentionally stressed towards the end, the team observed a reduction in total transmitted power.

 

Back on Earth, the team replicated this power decrease and determined that it was caused by the degradation of several transmitting elements in the array, along with complex electrical and thermal interactions.

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“These findings have already prompted revisions to various components of MAPLE to optimize its long-term performance,” says Ali Hajimiri, Bren Professor of Electrical Engineering and Medical Engineering and co-director of SSPP. "The space testing with SSPD-1 has provided us with a clearer understanding of our challenges and has strengthened our confidence in our capabilities."