Engineers affiliated with the China Academy of Space Technology and its Qian Xuesen Laboratory have laid out a concrete technical roadmap for building a kilometer-scale solar power station in orbit, one designed to collect sunlight continuously and transmit energy to ground receivers as microwave and laser beams. The proposal, backed by ground demonstrations and peer-reviewed research on beam-pointing accuracy, moves the concept from theoretical ambition toward engineering reality. However, significant gaps remain between simulated performance on the ground and the brutal demands of orbital operation, raising hard questions about whether the timeline can hold.
From Concept to kW-Level Demonstration
The core engineering blueprint comes from a 2025 mission proposal authored by researchers at the China Academy of Space Technology and partner institutions. That paper specifies a near-term demonstration targeting kW-level microwave power transmission at 5.8 GHz, alongside kW-level laser power transmission with precise beam control. These are not aspirational round numbers; they represent the minimum thresholds the team considers necessary to validate the full energy chain before scaling up. The choice of 5.8 GHz is deliberate, sitting in an industrial, scientific, and medical radio band that minimizes regulatory friction and atmospheric absorption, while still allowing for compact antenna designs on both the satellite and the ground.
What makes this proposal distinct from earlier space-based solar power concepts floated by NASA or the Japan Aerospace Exploration Agency is the explicit coupling of two transmission modes. Microwave beaming offers reliable all-weather penetration, while laser transmission promises tighter beam focus over long distances, at the cost of greater sensitivity to clouds and atmospheric turbulence. Combining both in a single demonstration mission allows engineers to compare real performance data side by side, rather than betting everything on one technology path. The approach reflects a hedging strategy: if one method underperforms in orbit, the other may still deliver usable power to ground stations, and hybrid architectures could eventually route power dynamically depending on weather and grid demand.
Ground Tests Already Mimic the Full Energy Chain
Orbital hardware is years away, but a full-link ground verification platform at Xidian University has already replicated every stage of the space solar power chain. The system, documented as part of the OMEGA-based SSPS prototype project, includes sun tracking, photovoltaic conversion, microwave emission, and rectenna reception and rectification. A June 2022 test on this platform demonstrated microwave wireless power transfer across the complete sequence, producing measurable DC output at the receiving end. That result matters because it proves the individual subsystems can work together as a single pipeline, not just in isolation on a lab bench, and it gives designers hard data on conversion losses at each step.
The research team behind the OMEGA prototype has emphasized that the ground verification system can mimic the key links of a real space solar power station in outer space, including sun tracking and energy conversion, according to a summary of the project. Still, a ground platform cannot replicate microgravity thermal cycling, radiation degradation, or the 36,000-kilometer transmission distance of geostationary orbit. The gap between a controlled university campus and the space environment is enormous, and no published data yet quantifies how much efficiency the system would lose under real orbital conditions. That uncertainty leaves planners to extrapolate from terrestrial reliability data and from broader aerospace research catalogs such as the NCBI-hosted literature, which document how materials and electronics behave under long-term radiation and vacuum exposure.
Beam Pointing: The Make-or-Break Technical Challenge
Transmitting kilowatts of microwave energy from orbit to a specific ground station demands extraordinary pointing accuracy. Even a fraction of a degree of drift at geostationary altitude translates into a beam footprint that misses the rectenna array entirely, wasting power and potentially raising safety concerns if energy spills into unintended areas. Separate peer-reviewed work published in Sensors has focused specifically on high-precision bi-directional beam-pointing measurement for space solar power station systems, reporting simulated improvements in offset-angle measurement accuracy. That research explores how to use cooperative signals between space and ground to measure tiny angular deviations and feed them into control loops that keep the beam centered on the rectenna, even as the satellite structure flexes and thermal gradients shift its components.
A complementary approach uses retrodirective antenna arrays that lock onto a pilot signal broadcast from the ground receiving station. Technical analysis of this method, published in the journal Space Solar Power and Wireless Transmission, describes how the orbiting array would detect the pilot signal from the ground and automatically steer its microwave beam back along the same path. This retro-reflective technique eliminates the need for the satellite to independently calculate its own position relative to the receiver, simplifying the control problem and potentially allowing for multiple ground stations that take turns sending pilot tones. However, the published work remains in the domain of antenna theory and simulation. No orbital test of a retrodirective array at the power levels envisioned for a full-scale station has been conducted, and the transition from simulated accuracy to demonstrated accuracy in space remains an open engineering question that mission planners will need to track through structured bibliographies such as those managed in curated NCBI collections.
Scaling Targets and the 2030 Milestone
China’s National Center for Science and Technology Information has outlined a phased expansion plan. By 2030, the program aims to expand the solar array to generate over 100 kilowatts and to test medium-power laser transmission across significant distances. That 100-kilowatt target represents a roughly hundredfold increase over the kW-level demonstrations currently proposed, which suggests the program envisions rapid iteration between its first orbital test and the next generation of hardware. It also implies a modular architecture, in which additional photovoltaic wings and transmitting arrays can be added over time without redesigning the entire platform from scratch.
The leap from 100 kilowatts to the gigawatt-class output that would make orbital solar power economically competitive with terrestrial renewables is far larger still. No published cost analysis or funding allocation from the Qian Xuesen Laboratory or the China Academy of Space Technology details how the program would finance the construction and launch of a kilometer-scale station, nor how launch vehicle constraints would shape the design of truss structures and deployable arrays. Analysts looking for analogs often turn to large-scale international projects in other domains, organizing references and technical precedents through personalized tools such as NCBI user libraries and account-level settings that help track evolving research on orbital assembly, in-space manufacturing, and high-power electronics. Until similarly detailed financial and engineering roadmaps are made public for the Chinese space solar power effort, the 2030 milestone will remain more of a technical aspiration than a guaranteed waypoint on the path to gigawatt-scale power from orbit.
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*This article was researched with the help of AI, with human editors creating the final content.
