Photosynthesis can make life in space, on Mars, Moon sustainable - study

Solar power could be used by humans on the Moon or Mars or traveling through deep space to support life by essentially conducting photosynthesis, a recent study revealed.

The findings of this study were published in the peer-reviewed academic journal Nature Communications.

The researchers from the University of Warwick present in their study a unique device to help create sustainable life support systems that, in theory, could be invaluable for establishing a human presence on Mars and the Moon.

Can there be life on Mars? How to make Mars and the Moon fit for human habitation through photosynthesis

Over the past several decades, humanity has made great strides in space exploration capabilities. Our technology has become more advanced and our scientific literature is broader and strengthened by years of research. 

Already, NASA is looking to bring humans back to the Moon for the first time in over 50 years, showing the technology and knowledge needed to do so is available and usable. 

Up until now, humanity's presence in space has been largely limited to space stations, which tend to exist in low-Earth orbit. That means that while they technically are in space, they aren't exactly far, with low-Earth orbit limited to around 2,000 kilometers. After this is medium-Earth orbit, which goes until over 35,700 kilometers from the Earth's surface, followed by high-Earth orbit. All of that precedes the Moon, which orbits the Earth at around 384,000 kilometers away.

This distinction is important because aside from the Apollo missions to the Moon in the late 1960s and early 1970s, all manned missions into space have been exclusively in low-Earth orbit.

Scientists are working towards changing that and bringing humanity farther out, such as returning to the Moon or even traveling to Mars. However, there remain several major hurdles that are still holding humanity back from becoming a spacefaring civilization.

These range from the needed propulsion systems to fly out quickly into such far-away places in space to the many health issues that can be caused by long-term space travel.

Another issue though is the lack of any life support systems in space, which is largely absent of an oxygen-rich atmosphere to enable any sort of long-term human presence.

Life support systems that are also sustainable are an essential requirement, which makes any advancement in this field highly valuable.

There already are life support systems used in space, such as the Oxygen Generator Assembly on board the International Space Station, which functions by electrolyzing water, meaning it uses electricity to split water into hydrogen and oxygen, with the oxygen then used for air supply. However, that system has high energy costs and is therefore not fit for going farther out into space. 

How can we make the Moon and Mars habitable?

The study proposed using something else: A photoelectrochemical (PEC) device. 

Rather than using electricity to turn water into oxygen, this sort of technology takes a different approach: Converting renewable solar energy to essentially conduct photosynthesis, using it to turn water into oxygen.

This system comes with numerous benefits. For one thing, it's much lighter than the hefty Oxygen Generator Assembly, which makes it ideal and efficient for space travel. 

Since it works by conducting photosynthesis, it could also help recycle other chemicals, specifically carbon dioxide.

Further, it won't just create oxygen from water: It can also create fuel. This is because when water is split into hydrogen and oxygen, only the latter is used for air supply. The former, however, can be repurposed for rocket fuel.

To test this, the researchers used a PEC device that could be used on the Moon, keeping in mind the theorized presence of ice water at the Shackleton Crater on the Moon – a location considered as a possible landing site for NASA's manned Artemis III mission to the Moon and for the first manned lunar outpost.

A similar scenario was also made for Mars. Both took into account the unique challenges and benefits of each location, such as the Moon being tidally locked and devoid of all atmosphere and having wildly fluctuating temperatures and the solar irradiance of Mars.

The conclusion is that both could theoretically work. However, there is a potential problem: Dust.

Both the Moon and Mars have considerable soil dust, and they can impact the transmission of sunlight into the PEC device. 

Technology will be needed to overcome this potential issue, such as giving the PEC devices some form of self-cleaning coating.

More research is needed to test out the effectiveness of PEC devices in these contexts – after all, they have yet to be tested in space. However, it is still a promising development and could help lead toward establishing a long-term human presence on the Moon or Mars.