However, the weight of the solar equipment required for the Mars outpost near the pole will be more than 20 tons. Mars is tilted about 25 degrees on its axis, slightly higher than Earth, and its orbits are less circular, so less sunlight will reach those PV cells in some parts of the year. That means nuclear energy becomes more efficient at the pole. The power generation equipment needed to produce so much nuclear power would add about 9.5 tons of carrying-mass to produce the same 40 kilowatts of energy. This lift is possible for NASA’s space launch system and for the next generation of giant next-generation rockets, such as SpaceX’s Starship and Super Heavy, which can carry at least ten tons of payload in each deep space. (The poles also contain ice, which can provide a source of water for astronauts.)
A similar trade-off has already arisen with the energy technologies used by Mars rovers. Engineers need to find the right balance between transport weight, storage needs, and a power system that can handle changes in sunlight availability. Significant sunlight reaches the surface only on Mars and only when dust and cloud particles do not enter, says Guillaume Anglada-Escude, an astronomer at the Institute of Space Sciences in Barcelona, who was not involved in the study. He is a member of the Sustainable Offworld Network, a collaboration of researchers, engineers and architects studying the future colonies of Mars and other worlds.
Anglada-Escudé agrees with the results of Abel and Berliner. He also believes that, if possible, solar and nuclear power should not be seen as either. “Our conclusion is, you want to get both solar and nuclear,” he says. “It’s a matter of resilience. Things can fail in different ways. The best option is to stay redundant. “
Daniel Vazquez Pombo, an energy engineer at the Technical University of Denmark, says it is also important to study solar luminosity and how dust and ice affect how much light reaches the planet’s surface and where that light can be collected. About a potential hybrid power system for a permanent Mars colony that includes PV arrays and storage. Maintenance of power systems can be risky for repair operators, another argument for having alternatives.
“Do you really want to rely on a single technology? What if you have a systemic flaw or a design flaw,” Pombo said. “Diversification is a smart idea. You don’t put all your eggs in one basket.”
Anglada-Escude argues that the calculus can change even when it is not just a handful of astronauts for a few months or a year, but a permanent colony with long-term visitors. “Solar panels are a relatively simple technology, and solar has become more attractive for a very long time,” he says. “You may need more mirrors, but it will work. On Mars, finding the quality plutonium you need for the reactor is not insignificant. There is solar, it’s safe, and we know how to do it.”
In the end, life on Mars will be harder than anywhere else on Earth. And science and technology issues are only half the story. Settlers also have to navigate complex financial and social issues, Abel said. At least when they get there, though, they will know how to keep the lights on.