Powering the Red Planet: Solar Energy Innovations for Mars Exploration
Exploring Mars is no small undertaking and is fraught with challenges. This article will examine how solar energy supports exploration on Mars.
According to NASA, Mars is one of the most explored bodies in our solar system, putting it at the forefront of solar system exploration.
Mars exploration faces countless challenges, but solar energy can help. Image used courtesy of Pixabay
In recent years, many government organizations and private companies have outlined ambitious plans for the red planet, including the European Space Agency's goal to put Europeans on Mars by 2040 and Elon Musk's ambition to colonize Mars via SpaceX.
Yet, Mars exploration faces countless challenges. How can solar energy help?
Solar Panels for Martian Efficiency
Mars is the 4th planet from the sun, with 142 million miles between it and the sun’s surface, in contrast to Earth, the 3rd planet from the sun (93 million miles). The result? Mars' solar irradiance (W/m2) is around 43.1% of Earth’s, making Mars less suitable for generating solar energy.
However, solar is still a strong option for Mars exploration but needs significantly more efficient solar technologies to meet energy requirements.
Photovoltaic panels are an excellent fit. This type of solar panel has already extensively been tested in space with applications to many satellites and space stations. They have also been widely used on satellites, landers, and rovers in Mars exploration. This includes the recent Opportunity Mars rover, declared dead in February 2019. But it does not include the current Mars rover Curiosity, which relies on radioactive isotopes that fulfill its higher energy demand and facilities used in darkness.
Sunlight on Mars: Challenges and Opportunities
With a rocky surface, canyons, volcanoes, and dry lake beds, Mars's surface is similar to some areas of Earth. However, several factors make Mars’ environment considerably more extreme than Earth's.
Mars is a cold desert with average temperatures reaching minus 80°F. It is covered in red dust, which, when paired with high winds, can create great dust storms, occasionally covering the entire planet. Although Mars has gravity, this is only about one-third as strong as the gravity on Earth. Mars also has a much thinner atmosphere than Earth, which comprises 95% CO2 and just 1% oxygen.
All these factors pose significant challenges to solar energy production on the planet.
Solar panels are a good fit for Mars. Image used courtesy of Pixabay
For example, although cold temperatures can be good for solar energy production, they can be harsh on some materials. They can also result in ice covering the panels, which can block sunlight. Similarly, dust storms can stop the sun’s energy from reaching the panel and leave dusty residue on them, which needs to be cleaned to ensure maximum energy production.
Innovative solutions must be developed if these challenges are to be overcome. For example, in the past, power output from solar panels was assumed to decrease over time due to dust cover, with no real solution to fix this. In fact, cleaning panels was purely down to luck. NASA even reported unknown ‘cleaning events,’ which saw an increased power overnight—this is thought to be the result of wind removing dust from the panels.
New approaches have been tried, such as pouring more dust onto the panels during the windiest part of the day. This dislodged the current layer of dust and allowed the wind to blow it away.
Unlike Earth's thicker atmosphere, which absorbs about 23% of incoming solar energy, Mars’ thinner atmosphere lets more solar energy through. This makes more of the sun’s energy that reaches Mars available for conversion into electricity.
Perovskite Solar Cells: A Martian Game-Changer?
Technologies such as perovskite solar cells may be game-changers for solar energy production on Mars.
Perovskite cells use a family of materials shown to increase performance and reduce production costs. It has seen huge improvements in efficiency in recent years, increasing from 3% in 2009 to over 25% today. Although this is still slightly lower than some other technologies, the speed at which efficiency is increasing and the flexibility of perovskite panels could make them a more suitable alternative in the coming years.
In fact, by applying different architectures, some studies suggest the perovskite cells could achieve up to 39% efficiency, in stark contrast to traditional silicone efficiency of 29%.
Of course, there are still challenges to overcome, especially regarding stability and durability. Perovskite cells can decompose rapidly in certain conditions, such as those with high moisture or oxygen.
Localized Solar Panel Production on Mars and the Moon
Putting humans on Mars and achieving ambitious research projects will require significantly higher energy production levels. This produces a major challenge - primarily in transporting large quantities of energy production methods (such as solar panels) to Mars’s surface.
One potential and highly innovative solution is the production of solar panels on Mars itself. This is being explored by Jeff Bezos’ US-based space company Blue Origin—although its project, ‘Blue Alchemist,’ currently focuses on the potential to do this on the moon.
The team behind this project has synthesized a terrestrial material that approximately matches the rocks and dust found on the moon (known as lunar regolith). They then use a reactor to perform regolith electrolysis, producing iron, silicon, aluminium, and oxygen. All of these can be used to make solar panels, except oxygen, which could be used to sustain life.
Although significant further research and development is required, this process could be applied to materials found on the surface of Mars.
Energy Storage: Batteries on Mars
Many of the adverse conditions on Mars mean sunlight is not always available for energy production. For equipment like rovers, this is an inconvenience. Yet, if plans to colonize Mars come to fruition, a lack of consistent energy could mean the difference between life and death.
Batteries offer an obvious solution, allowing excess solar energy to be stored for use when sunlight is unavailable. However, the large-scale batteries that would be required are incredibly heavy, making them extremely expensive to transport to Mars.
Current solar batteries also only have a lifespan of 10 to 15 years. This is likely even shorter in the harsh conditions of Mars and would require energy-intensive temperature regulation, making sustaining a long-term colony on Mars unsustainable.
In reality, alternative storage methods or drastic advances in battery technology are the only way for long-term colonization of Mars.
Solar on Mars
There are ambitious plans for the future of Mars, including sending humans to its surface within the next 20 years.
Solar energy already plays a key role in powering the equipment used to explore the red planet, such as rovers and satellites. Innovative projects such as Blue Origin pave the way to make these ambitious targets a reality. We will likely continue to see focus on improving solar and energy storage technology to understand the planet and its resources better.