Space Solar Wireless Power Station SolarBeam Transmits Power from Orbit to Earth for the First Time

Space Solar Wireless Power Station SolarBeam Transmits Power from Orbit to Earth for the First Time

On March 9, 2029, the Japan Aerospace Exploration Agency (JAXA) announced that its SolarBeam space solar power project completed the first empirical test of power transmission from orbit to Earth. A test satellite in a 400-kilometer low-Earth orbit transmitted approximately 2kW of electricity via microwave beam to a ground receiving station on the Ogasawara Islands, sustaining transmission for about 12 minutes.

The concept of space-based solar power (SBSP) was first proposed by Peter Glaser in 1968: deploying solar panels in space, free from atmospheric and day-night limitations, enabling 24-hour continuous power generation, then wirelessly transmitting energy to Earth via microwave or laser. Theoretically, space solar power generation efficiency is 5 to 10 times that of ground-based photovoltaics.

JAXA SolarBeam project lead Hiroyuki Hirokawa said: "2kW is a small amount — enough to run an electric kettle. But it validates the entire technology chain: space solar power generation, microwave energy conversion, precise beam pointing control, and ground rectenna reception."

During this test, the satellite's 2-meter-diameter phased array antenna converted DC power into a 2.45GHz microwave beam, directed at the ground receiving station with approximately 0.3-degree precision. The ground rectenna array, covering about 10 square meters, converted microwave energy back into DC power. End-to-end efficiency from solar energy to final power output was approximately 8%.

JAXA's long-term goal is to deploy a 1GW-class SBSP station before 2040, with estimated costs of approximately 2 trillion yen (about $13 billion). ESA and China Aerospace Science and Technology Corporation are also conducting similar SBSP research programs.

University of Tokyo aerospace engineering professor Kimihiko Nogiwa noted: "There's a gap of six orders of magnitude between 2kW and 1GW. The biggest technical challenge for SBSP isn't power generation or transmission per se — it's how to assemble and maintain ultra-large structures in space at acceptable cost. A 1GW SBSP station might require solar cell areas spanning several square kilometers."