AE celebrates Hispanic Heritage Month and spotlights Professor Álvaro Romero-Calvo and his exciting work.
AE Assistant Professor Álvaro Romero-Calvo’s research connects space engineering and fluid mechanics, and he is studying how to split water into oxygen and hydrogen with the aid of magnetic forces. This research could put humans one step closer to extended stays on the moon and make it a fueling station for those traveling deeper into space. Water may hold the key to more efficient deep space exploration.
The moon's south pole holds water, a combination of two hydrogen molecules and one oxygen molecule. Romero-Calvo’s research aims to process this water using electrolysis, a standard chemical method that involves passing an electric current through the liquid to split it into its fundamental components. Hydrogen appears at the negative electrode, while oxygen occurs at the positive electrode. The gas molecules then rise to the water's surface as bubbles, which are collected to support a variety of space applications.
The Moon is particularly challenging for electrolytic cells because of its reduced gravity, which is just 1/6 of the Earth’s. Without enough buoyancy, gas bubbles take longer to detach and reach the surface. The problem is even worse in an orbiting spacecraft, where buoyancy practically disappears due to the microgravity environment. This calls for a mechanism to separate those bubbles, and Romero-Calvo’s solution is to use magnetohydrodynamic forces.
“One of the most exciting innovations that we are pursuing at the lab is using magnetic forces applied to liquid electrolytes to detach gas bubbles from the electrodes and move them to desired collection points. We are developing an efficient, lightweight, completely passive method to achieve this goal, and that has far-reaching implications for astronaut life support, spacecraft propulsion, or in-situ resource utilization.”
The plan is solid but has its challenges, too. For one, water is stuck in cold traps at the moon's south pole. These traps are frigid. It is difficult to send anything there that can survive the extreme temperatures over a long period.
Motivated by the NIA RASC-AL competition, Romero-Calvo’s senior design students are working on rovers that will operate in this environment. Under his advisement, Georgia Tech Team LOTUS (L1 Orbiting Tracking and Uplink Spacecraft) won the best paper at NASA’s 2023 Revolutionary Aerospace Systems Concepts-Academic Linkage (RASC-AL) competition.
Diamagnetic separation of gas bubbles in microgravity.
(L: non-magnetic, C: right magnet, R: left magnet)
Conceptual representation of the magnetically enhanced electrolysis approach
Romero-Calvo is exploring these ideas in collaboration with Professor Katharina Brinkert at the University of Warwick, UK. Her group specializes in solar-driven photoelectrochemical cells that can potentially simplify the architecture of future space electrolyzers. Early results from this joint effort, funded by the European Space Agency (ESA), the German Aerospace Center (DLR), and obtained at ZARM’s drop tower in Bremen, Germany, can be consulted in the paper “Magnetic phase separation in microgravity,” that was recently published in the journal NPJ Microgravity.
Romero-Calvo’s magnetohydrodynamic method could also have applications for fuels. Launch vehicle propellants are commonly made up of hydrogen and oxygen because they are highly efficient in terms of mass. So, researchers who can extract water from the moon's south pole and transform it into a propellant will make deep space travel more manageable. Spacecraft can stop on the moon and refuel before going to another destination.
“Developing efficient water processing technologies for space applications is important because to bring anything to orbit, we must overcome the Earth's gravitational pull,” he explained. “If astronauts have the fuel waiting for them on the moon, it means we can send far more payload mass to deep space. It will enable humans to reach other space destinations in a very efficient and cost-effective way. In many senses, it is a game changer.”
The Man Behind the Research
Romero-Calvo came to Georgia Tech from a small city in Spain called Granada. He went on to study aerospace engineering at Universidad de Sevilla, Spain. Then, he moved to Milano, Italy, to earn his master’s degree in space engineering at Politecnico di Milano. After completing his master's, he received fellowships from the La Caixa and Rafael del Pino foundations for his Ph.D. at the University of Colorado, Boulder, before landing at Georgia Tech.
He always had an interest in math and physics, and it helped that he was also good at it. Before choosing an aerospace engineering career, he considered being a computer scientist specializing in cyber security but found that it wasn’t as exciting for him as exploring deep space.
In addition to his love of science and math, Romero-Calvo also loves music. In fact, he’s been playing the piano since he was five years old. At 18, he was at a crossroads because he wasn’t sure if he should become a professional pianist or do math and physics. He finally made the call to become an engineer and enjoy the piano as a hobby.
“I wanted to become a professor because I saw that the main innovations in engineering, the most disruptive concepts that would be too risky for industry to carry out, were done by professors at the academic level, at least in Europe or Spain. So, I chose the independence and freedom to pursue my own ideas as a professor.”
Today, he leads the Low-Gravity Science and Technology (LGST) Lab and compares it to running his own small company because he has to manage the business side of it in addition to the academic aspects, but he also has the freedom to explore topics that he finds most attractive. He wouldn’t have it any other way.
He also teaches the Space Systems Design AE 4321 Capstone course and has led several teams to victory in school-wide and national competitions. Team TRTL (Taxi Rendezvous, & Taxi Launcher) took first place, and Team COAST (Crewed Orbit and Ascent Surface Transport) took third place in this year’s AIAA Undergraduate Team Space Design Competition.