Space solar power in orbit: Challenges for future NASA, ESA, and Xi’an solar observatory systems at 50,000 miles
For the project to go forward, Vijendran and his team must determine by 2025 that it’s indeed possible to achieve space-based solar in a cost-efficient way. In the 70s and ’80s NASA and the Department of Energy worked on the idea, but decided against it because of the costs and technological challenges. Still, much has changed since then. The launch costs have gone down due to the reuse of rockets. Satellites have become cheaper to mass-produce. And the cost of photovoltaics, which convert sunlight into electricity, has fallen, making solar power in orbit more competitive with terrestrial energy sources.
The program—unrelated to Stanisław Lem’s sci-fi novel with the same name—is considered a “preparatory” one, meaning the ESA has already completed a pilot study, but it’s not yet ready for full-scale development. It calls for designing an in-orbit demonstration of the technology, launching it in 2030. developing a small version of a space solar power plant in the near future. In order to investigate the possibility of robotically assembling a large solar array at a altitude of about 50,000 miles, the researchers from the European Space Agency will begin. This way, the structure would remain continuously above a particular point on the ground, regardless of the Earth’s rotation.
China has announced plans to put a megawatt-scale demonstration unit in low-Earth orbit in 2028, before deploying another system to a more distant geosynchronous orbit in 2030. Carpenter says that, with sufficient funding, the first multigigawatt solar power station could be operational by 2040. But despite the excitement, huge technical hurdles remain.
Other projects use different designs. Among the proposals ESA’s Solaris initiative is considering is a helical structure, and in Xi’an, China, Xidian University’s Chasing the Sun project is developing a crown-shaped solar collector. Both would require remote assembly by robots in orbit, a still-nascent technology.
Karen Jones, a space economist at the Aerospace Corporation in Arlington, Virginia, says the engineering of such systems is incredibly complex. Caltech hopes to side-step this problem by flying its flexible panels in formation, without tethering them together, and using algorithms to correct for any fluctuations in position that affect power transmission. A design that is used would need components to be launched weekly, a rate that would be unprecedented according to a chemical engineer at a UK university.
To that end, an experiment on the Caltech prototype will trial 32 lightweight photovoltaic cells, including low-cost perovskites. “The idea here is to kind of do a longevity test,” says Ali Hajimiri, who co-leads the Caltech project.
The Safest Beam of Microwave Energy From Space: A Recommendation for the Research of Human-Machine Interactions
Beaming microwave energy from space is surprisingly safe. The beam’s frequency will be chosen so that it does not disrupt aircraft communication. The average energy density for ground stations would be 50 watt per square metre, which is similar to the level of microwaves leaking from a microwave oven. “It’s within what would be considered a normal safety recommendation for human exposure,” he says.
Researchers will have to show that there are no adverse effects on humans, animals or the environment. “I think they need to take the lead from the mobile-wireless industry that went through the same concerns, and to not trivialize these concerns, but prove it with studies,” says Jones.