As humanity plans an expedition to the Martian surface, one would speculate that nuclear power would be the best option for faraway crewed missions. Researchers at the University of California (UC), Berkeley, have now shown that a crewed mission to Mars could be powered by solar energy.
The current study is unique because the researchers compared the distinct ways of generating power and evaluated the requirements of a nuclear-powered system against various photovoltaic devices and photoelectrochemical devices. Photovoltaic devices are those devices that convert sunlight directly into electricity, whereas photoelectrochemical devices convert abundant solar energy into stored electrical energy.
Comparing The Power Generating Options
A small nuclear fission device is location-agnostic (independent of nuclear outpost location establishment), while the efficiency of solar power devices relies on the intensity of sunlight, surface temperature and other factors that would decide where a non-nuclear outpost would be perfectly located. Several factors, such as how particles and gases in the atmosphere absorb and scatter the sunlight, which would affect the amount of solar radiation on the surface of Mars were also analyzed.
Photovoltaic devices that used compressed hydrogen turned out to be the best for storing energy. At the equator, the “carry-along mass” of the photovoltaic system was found out to be 8.3 tons, whereas it was about 9.5 tons for the nuclear power systems. Further, the solar-based system became less sustainable closer to the equator at more than 22 tons but won against the nuclear fission system across about 50 percent of the surface of Mars.
The study suggested that the crewed missions could be successfully carried out at the Martian equator using solar energy as it is highly rich in solar intensity and has a high surface temperature. Hence, the solar-based system beats the nuclear fission system across about 50 percent of the surface of Mars.
“I think it’s nice that the result was split pretty close down the middle,” said Aron Berliner, a Bioengineering Graduate Student in the Arkin Laboratory at the University of California, Berkeley. “Nearer the equator, solar wins out; nearer the poles, nuclear wins.”
Of the two options, the photovoltaic devices were considered as they use compressed hydrogen for storing energy. The system can use electricity to break water molecules to produce hydrogen, which can be stored in pressurized vessels and then re-electrified in fuels for power. The unwanted hydrogen is combined with nitrogen to produce ammonia to fertilize plants.
“Compressed hydrogen energy storage falls into this category as well,” said Anthony Abel, a Chemical and Biomolecular Engineering PhD student at UC Berkeley. “For grid-scale energy storage, it’s not used commonly, although that is projected to change in the next decade.”
Relying On Nature
Both Berliner and Abel are members of the Centre for the Utilization of Biological Engineering in Space (CUBES). It is a project that develops biotechnologies to support space exploration. For example, CUBES is interested in engineering microbes that could produce plastics from carbon dioxide and pharmaceuticals or hydrogen from light and carbon dioxide.
“Now that we have an idea of how much power is available, we can start connecting that availability to the biotechnologies in CUBES,” said Berliner. “The hope is ultimately to build out a full model of the system, with all of the components included, which we envision as helping to plan a mission to Mars, evaluate tradeoffs, identify risks, and come up with mitigation strategies either beforehand or during the mission.”
The detailed research has been published in the journal Frontiers in Astronomy and Space Sciences.
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