HELSINKI — China is planning solar power generation and transmission tests at different orbital altitudes over the next decade as part of a phased development of a space-based solar power station.

The China Academy of Space Technology (CAST), the country’s main, state-owned spacecraft maker, plans to conduct a “Space high voltage transfer and wireless power transmission experiment” in low Earth orbit in 2028.

The satellite will be capable of generating 10 kilowatts and carry a solar cell array, microwave transmitting antenna, a low power laser transmission payload, a transmitting array and test power transmission across distances of 400 kilometers from orbit.

The plan also involves building infrastructure on the ground for receiving energy transmissions.

The update to CAST’s plans appears in the paper “Retro-directive microwave power beam steering technology of space solar power station,” published in the journal China Space Science and Technology last week.

The paper was first reported by the South China Morning Post June 7. The move means a first satellite in orbit two years earlier than planned, with CAST previously stating a goal of launching a megawatt-level satellite by 2030.

The 2028 phase 1 test is to be quickly followed by phase 2 in 2030, launched into geostationary orbit, requiring accurate energy transmission over a distance of 35,800 kilometers to Earth.

This second mission would generate up to one megawatt, feature much larger transmission arrays and medium power laser power transmission and require on-orbit assembly.

Phases 3 and 4, in 2035 and 2050, each demand very challenging increases in energy generation (10 MW and 2 gigawatts) and transmission, orbital assembly capabilities, beam steering accuracy and transmission architecture.

The spacecraft would require transmission arrays of larger than 100 meters and around 1 kilometer respectively.

The paper, authored by Dong Shiwei, of the State Key Laboratory of Space Microwave Technology under CAST, and two others with the Qian Xuesen Space Technology Laboratory and Chongqing University, claim the four-phase project could assist with China’s energy security and carbon neutrality goals.

The updated plan is in part a response to domestic and international development trends and progress in technological research. 

CAST stated in 2021 that it is working towards small-scale electricity generation tests in 2022, potentially leading to a megawatt-level power generation facility around 2030. It is constructing test facilities in Chongqing to support its space-based solar power research.

Last year it tested power transmission over a distance of 300 meters using a payload aboard a small airship.

Space-based solar power test: China’s Aerospace Info Research Institute under CAS carried experiments including 300m line-of-sight microwave transmission using the Zhihai research vessel & 30kg payload on small airship. Early research for potential space-based solar power project

— Andrew Jones (@AJ_FI) August 19, 2021

Research into construction of kilometer-scale objects in orbit received support last year funding, which would be a major challenge in assembling the giant arrays needed for solar power collection and transmission arrays.

In a related development, a senior official with the China Academy of Launch Vehicle Technology (CALT), like CAST a subsidiary of China’s main space contractor, CASC, last year presented a plan for using a reusable Long March 9 super-heavy launch vehicle for construction of a space-based power station in GEO.

The project is far from certain to proceed or gain official approval. Space-based solar power faces major challenges including economic feasibility and manufacturing costs, cheap and reliable launch services, and efficient and safe energy transmission.

Andrew Jones covers China's space industry for SpaceNews. Andrew has previously lived in China and reported from major space conferences there. Based in Helsinki, Finland, he has written for National Geographic, New Scientist, Smithsonian Magazine, Sky...