How to Harvest Lunar Water
NADIA M. WHITEHEAD | October 10, 2013 | UNIVERSITY COMMUNICATIONS
Sergio Guerrero (right) is one of several undergraduate researchers
who are working together to construct a rover that can harvest
water from the moon. Evgeny Shafirovich (left), Ph.D., assistant
professor of mechanical engineering, is advising the team on their
Photo by Laura Trejo / UTEP News Service
In 2009, NASA discovered an incredible resource on the moon – water.
"When people realized there was water on the moon they started to think, 'How do we extract this?'" said Evgeny Shafirovich, Ph.D., assistant professor of mechanical engineering and co-investigator of UTEP's Center for Space Exploration Technology Research (cSETR). "Of course, water is very useful. People can drink it, and it's also possible to split water and make it into hydrogen and oxygen, which is a very nice rocket propellant."
The problem is that water on the moon is not easily accessible.
It's frozen at negative 400 degrees Fahrenheit, and mixed into lunar regolith – the layer of loose dust, sand and rock covering the moon. It's also only located in permanently shadowed areas, or craters, near the South Pole.
However, sometime after NASA's discovery, Shafirovich was approached by Michael VanWoerkom, who had developed an idea on how to potentially harvest the water and was looking for research collaborators.
"My idea was basically to use solar energy to heat water in the soil, evaporate it, collect the vapor, and pump it into tanks," said VanWoerkom, who founded ExoTerra Resource, a company that is resolved to become the solar system's first space "utility" business. "By doing that you can avoid [collecting] the lunar dust, and rely on a power source [the sun] that we can always tap into."
Interested, Shafirovich and graduate student Jorge Frias hopped on board and began designing a system to carry out VanWoerkom's concept.
To find out how much energy is needed to collect, say, one gallon of water on the moon, the researchers modeled the transfer of concentrated sunlight into the lunar surface. They then recreated the moon's parameters using a lunar regolith simulant and designed an apparatus that applies heat to the regolith with a laser. Water within the soil evaporates into tubing above, and is condensed into liquid in a separate storage tank.
While Frias successfully defended his master's thesis and now works as a drilling engineer for an oil company, Shafirovich is taking the concept a step further with a team of undergraduate researchers who are constructing a rover with the apparatus attached.
"Our project is to make this whole setup mobile," said Sergio Guerrero, one of the undergraduate researchers. "Once you get water from the surface of the moon, you need to be able to get it up and move it to another location to continue collecting water."
The team, which consists of Guerrero, Domingo Estrada, Deanna Key, Felipe Nunez, and Alex Whisler, has designed a 1.5-by-2-foot vehicle that lowers the heating apparatus toward the ground. Once the water evaporates and is collected into a storage tank located on the rover, the vehicle will raise the heating system and move on to another spot.
"Of course, we don't have the resources to test this on the moon," Guerrero said. "So we're thinking of a constructing a box and filling it with sand [and water]. As long as you have the water and it evaporates, that's the critical point."
In order to actually work on the moon, a few adjustments would have to be made. Since the frozen water is located in permanently shadowed areas, solar power would have to be beamed down to the rover via satellite. A solar concentrator attached to the rover would collect the beamed energy in order to operate.
"Obviously, we couldn't afford to have a satellite sending a beam of energy to our rover here on Earth," Guerrero said. "This is just the first initial design to complete the mission."
The undergraduate team expects to complete their rover in December as part of a mandatory senior design class.
"This has been a really cool project. Who wouldn't want to get water from the moon?" Guerrero asked enthusiastically. "If President Obama wanted to set up a shelter on the moon, this would be important to work on. Right now industry is profiting on people who want to go to space. Maybe someday in the future, we'll even set up a hotel on the moon."
If so, harvesting water from the moon would be absolutely critical.
To learn more details about the project, a paper discussing the findings of Frias, Shafirovich and VanWoerkom will appear in the Journal of Thermophysics and Heat Transfer, published by the American Institute of Aeronautics and Astronautics, later this year.