How should we power a mission on Mars?

As humanity turns its attention to Mars, with manned missions tipped to launch by the 2030s, the question of how we might power those missions is becoming ever more important. To safely live, work and travel on the surface of Mars will require significant amounts of energy – so what’s the best way to get it?

While the main source of power for NASA’s Mars rovers comes from a solar array, most scientists have assumed that to power a manned mission would require a more reliable and constant power source – in this case nuclear energy, powered by a miniaturised nuclear fission device. That’s because solar energy isn’t being produced at night, or during a dense dust storm.

But a new study published in Frontiers in Astronomy and Space Sciences has found that might not be the case. 

Weighing up the options

In a first-of-its-kind investigation, researchers from the University of California Berkeley, US, compared various methods for generating power on the red planet, taking into account the equipment mass required for a six-person mission including a 480-day-stay on the surface, as well as local factors such as how gases in the atmosphere might absorb and scatter light. 

When they crunched the numbers, they found that a photovoltaic array that uses compressed hydrogen for energy storage could be a more effective power source across at least half of the planet, when you take into account the weight of the solar panels and their efficiency.

The key is the hydrogen gas, which can store the energy to power a Mars base at night or during a dust storm, making the array just as reliable as a fission device and with a reduced mass – at least closer to the equator. Nearer to the poles, nuclear energy wins out, because solar arrays would be less productive.

“I think it’s nice that the result was split pretty close down the middle,” says co-lead author Aaron Berliner, a bioengineering graduate at UC Berkeley. “Nearer the equator, solar wins out; nearer the poles, nuclear wins.”

But such a solar array would require a more modern, lightweight and flexible solar panel.

“The silicon panels that you have on your roof, with steel construction, glass backing etc, just won’t compete with the new and improved nuclear,” says co-lead author Anthony Abel. “But newer lightweight, flexible panels all of a sudden really change that conversation.”

Powering life on Mars

In the past, NASA estimates of the power needs of astronauts on Mars have focused on short stays. But as talk of long-term settlement grows, scientists have turned their attention to how you can support human life – providing food, fuel, materials and medicine – during a long stay on the planet.

That’s how Berliner and study co-lead author Anthony Abel first came up with the study concept. They’re both members of the Centre for the Utilisation of Biological Engineering in Space (CUBES), a multi-university project to genetically engineer microbes that could produce food, materials and drugs. But without knowing how much power would be available on an extended mission, they realised they couldn’t assess the practicality of any bio-manufacturing processes. 

So, they built a computer model of various power demands, including habitat maintenance, fertiliser production for agriculture, methane production for rocket propellant to return to Earth, and bioplastics production for manufacturing spare parts.

Berliner, who is also pursuing a degree in nuclear engineering, came to the study with a bias towards nuclear power, while Abel was more in favour of solar power.

“I feel this paper stems from a healthy scientific and engineering disagreement on the merits of nuclear versus solar power, and that really the work is just us trying to figure out and settle a bet,” Berliner said. ” I think I lost, based on the configurations we chose in order to publish this. But it’s a happy loss, for sure.”