Last June, Caltech’s Space Solar Power Demonstrator (SSPD-1) launched into space to demonstrate and test three technological innovations needed to make space solar power a reality, as we reported in Mindplex News.

Now, with SSPD-1’s mission in space concluded, engineers on Earth are celebrating the testbed’s successes and learning important lessons that will help chart the future of space solar power. All of the experiments aboard SSPD-1 were ultimately successful.

“Solar power beamed from space at commercial rates (‘lighting the globe’), is still a future prospect. But this critical mission demonstrated that it should be an achievable future,” says Caltech President Thomas F. Rosenbaum, the Sonja and William Davidow Presidential Chair and professor of physics. 

SSPD-1 represents a major milestone in a project that has been underway for more than a decade, consisting of three main experiments, each testing a different technology are ultra-lightweight, cheap, flexible, and deployable:

• DOLCE (Deployable on-Orbit ultraLight Composite Experiment) will eventually become a kilometer-scale constellation to serve as a power station. It had two problems, which were fixed.
• ALBA: photovoltaic (PV) cells to enable an assessment of the types of cells that can withstand punishing space environments. They tested various designs.
• MAPLE (Microwave Array for Power-transfer Low-orbit Experiment): an array of flexible, lightweight microwave-power transmitters to demonstrate wireless power transmission at distance in space. MAPLE demonstrated its ability to transmit power wirelessly in space and to direct a beam to Earth—a first in the field. “These observations have already led to revisions in the design of various elements of MAPLE to maximize its performance over extended periods of time,” says Hajimiri, Bren Professor of Electrical Engineering and Medical Engineering and co-director of SSPP.

SSPD-1 will remain in orbit to support continued testing and demonstration of the vehicle’s Microwave Electrothermal Thruster engines. It will ultimately deorbit and disintegrate in Earth’s atmosphere. Meanwhile, the SSPP team continues work in the lab, studying the feedback from SSPD-1 to identify the next set of fundamental research challenges for the project to tackle.  

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