Astronauts on Mars will need oxygen. There's oxygen in the atmosphere, but only small amounts. But there's lots of subterranean water on Mars, and that means there's lots of oxygen, too. (Credit: NASA)
Throughout the 20th century, multiple proposals have been made for the crewed exploration of Mars. These include the famed “Mars Project” by Werner von Braun, the “Mars Direct” mission architecture by Robert Zubrin and David Baker, NASA’s Mars Design Reference Mission studies, and SpaceX’s Mars & Beyond plan. By 2033, two space agencies (NASA and the CNSA) plan to commence sending crews and payloads to the Red Planet. These and other space agencies envision building bases there that could eventually lead to permanent settlements and the first “Martians.”
This presents several major challenges, not the least of which have to do with exposure to radiation, extreme temperatures, dust storms, low atmospheric pressure, and lower gravity. However, with the right strategies and technology, these challenges could be turned into opportunities for growth and innovation. In a recent paper, a Leiden University researcher offers a roadmap for a Martian settlement that leverages recent advancements in technology and offers solutions that emphasize sustainability, efficiency, and the well-being of the settlers.
Just a sample of Chris Hadfield's creativity in sharing his space experience. 'Weightless water. This picture is fun no matter what direction you spin it,' he said via Twitter.
In the near future, NASA and other space agencies plan to send crews beyond Low Earth Orbit (LEO) to perform long-duration missions on the Moon and Mars. To meet this challenge, NASA is developing life support systems that will sustain crew members without the need for resupply missions from Earth. These systems must be regenerative and closed-loop in nature, meaning they will recycle consumables like food, air, and water without zero waste. Currently, crews aboard the International Space Station (ISS) rely on an Environmental Control and Life Support System (ECLSS) to meet their needs.
This system recycles air aboard the station by passing it through filters that scrub excess carbon dioxide produced by the crew’s exhalations. Meanwhile, the system uses advanced dehumidifiers to capture moisture from the crew’s exhalation and perspiration and sends this to the Water Purification Assembly (WPA). Another subsystem, called Urine Processor Assembly (UPA), recovers and distills water from astronaut urine. To boost the WPA’s efficiency, the crew integrated a new component called the Brine Processor Assembly (BPA), which recently passed an important milestone.
The prototype greenhouse is being designed to provide astronauts with a continuous vegetarian diet. Image: University of Arizona.
NASA is all about solving challenges, and the goal of having a prolonged presence in space, or a colony on Mars or some other world, is full of challenges, including the necessity of growing food. Scientists at Kennedy Advanced Life Support Research are working on the Prototype Lunar/Mars Greenhouse Project to try and meet that challenge.
The Prototype Lunar/Mars Greenhouse Project (PLMGP) is all about growing vegetables for astronauts during extended stays on the Moon, on Mars, or anywhere they can’t be resupplied from Earth. Beyond growing food, the Project aims to understand how food-growing systems can also be a part of life-support systems.
“The approach uses plants to scrub carbon dioxide, while providing food and oxygen.” – Dr. Ray Wheeler
“We’re working with a team of scientists, engineers and small businesses at the University of Arizona to develop a closed-loop system. The approach uses plants to scrub carbon dioxide, while providing food and oxygen,” said Dr. Ray Wheeler, lead scientist in Kennedy Advanced Life Support Research.
The prototype itself is an inflatable, deployable system that researchers call a bioregenerative life support system. As crops are grown, the system recycles, water, recycles waste, and revitalizes the air.
The system is hydroponic, so no soil is needed. Water that is either brought along on missions or gathered in situ—on the Moon or at Mars for example—is enriched with nutrient salts, and flows continuously through plant root systems. Air in the system is recycled too. Astronauts exhale carbon dioxide, which plants absorb. Through photosynthesis, the plants produce oxygen for the astronauts.
This 18 foot long tube is a prototype of a bioregenerative life support system. The system grows crops, but also regenerates water and air. It’s at the University of Arizona’s Controlled Environment Agriculture Center. Image: University of Arizona
“We’re mimicking what the plants would have if they were on Earth and make use of these processes for life support,” said Dr. Gene Giacomelli, director of the Controlled Environment Agriculture Center at the University of Arizona. “The entire system of the lunar greenhouse does represent, in a small way, the biological systems that are here on Earth.”
“The entire system of the lunar greenhouse does represent, in a small way, the biological systems that are here on Earth.” – Dr. Gene Giacomelli
A key part of a system like this is knowing what astronauts will have to bring with them, and what resources they can find at their destination. This includes which type of plants and seeds will be needed, as well as how much water might be available once astronauts reach their destination. Methods of extracting water on Mars or the Moon are also being researched and developed.
Even if the necessary water can be found in situ on Mars and the Moon, that hardly means those are easy places to grow food. Astronauts have to be protected from radiation, and so will crops. These greenhouse chambers would have to buried underground, which means specialized lighting systems are also required.
“We’ve been successful in using electric LED (light emitting diode) lighting to grow plants,” Dr. Wheeler said. “We also have tested hybrids using both natural and artificial lighting.” Solar light could be captured with light concentrators that track the sun and then convey the light to the chamber using fiber optic bundles.
These systems are not NASA’s first experience at growing crops in space. Experiments aboard the International Space Station (ISS) have been an important part of the research into crop production in non-terrestrial environments. The Veggie Plant Growth System was NASA’s first attempt, and astronauts successfully harvested lettuce from that system.
NASA astronaut Shane Kimbrough harvesting lettuce from ‘VEGGIE’ on the International Space Station. Image: NASA
Earth has well-established systems for sustaining life, and this project is all about taking some of that to distant destinations in space.
“I think it’s interesting to consider that we’re taking our terrestrial companions with us,” Wheeler said. “While there may be ways to engineer around it in terms of stowage and resupply, it wouldn’t be as sustainable. The greenhouses provide a more autonomous approach to long-term exploration on the moon, Mars and beyond.”
