Thermal vacuum chamber where the CubeSat was tested.

Photo courtesy Prof. Mason Peck

Thermal vacuum chamber where the CubeSat was tested.

October 11, 2016

Research Team Prototypes Spacecraft Propelled by Water

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What would you explore if you owned your own spacecraft? The rings of Saturn? The surface of Mars? Research conducted by Cornell University’s Cislunar Explorers could soon make these dreams a reality.

By trying to create a spacecraft capable of using water as rocket fuel, Prof. Mason Peck, mechanical and aerospace engineering, and his team of engineers, hopes to revolutionize space exploration.

“Life on Earth and the success of human civilization is dependent on sunlight and water,” Peck said. “The things that make us successful inhabitants of this planet can make us successful inhabitants of other planets. In this case, our spacecraft uses those everyday resources to explore the cosmos.”

CAD rendering of the CubeSat

Photo courtesy Prof. Mason Peck

CAD rendering of the CubeSat

The Cislunar Explorers team, named for its mission of exploring regions between the Earth and the Moon, has an extraordinary goal. The team, comprised of Peck, Kyle Doyle grad and several other students, aims to send a spacecraft, nicknamed CubeSat, around the moon using nothing but an object “the size of a cereal box”. If successful, this 10x20x30 spacecraft will be the first to demonstrate water based propulsion by storing the liquid during launch and converting it to rocket fuel once in orbit.

“We’re trying to demonstrate that water is all you need for sustainable exploration of the solar system,” said Peck, who previously served as NASA’s chief technologist. “If we could depend on the mass that is already in space, such as water, to fuel the spacecraft, the cost would be significantly lower and we could do a lot more exploration.”

The spacecraft uses a process known as electrolytic propulsion to move. Electrolytic propulsion is the breakdown of a liquid, using an electric current, into simpler chemicals that can be used to enable thrust. In this case, water is broken down into hydrogen and oxygen to be burned as rocket fuel. The team made important design decisions to ensure that such a process could even be used. The spacecraft is made up of two L-shaped halves that separate after launch, causing each to spin. This spin helps separate liquid water from the hydrogen and oxygen produced during electrolysis.

Doyle uses the analogy of exploring New York City to explain how the CubeSat pinpoints its exact location.

“I think for the optical navigation system the best analogy would be landmarks. We’re looking at the sun, the earth and the moon and we know at any given moment where the three bodies are. We take pictures of them from our spacecraft which tells us where it is in reference to those bodies,” Doyle said. “It’s very much like navigating your way in New York City by looking at the Empire State Building or following landmarks anywhere else.”

Doyle points out that in order to maximize efficiency and minimize the use of resources, the team intertwined different aspects of the CubeSat. A specific example is the use of water on board the spacecraft. He said the team carries water on board to use as a propellant, but also uses it for other things, and needs heat to keep the liquid from freezing.

“Another problem we face is that in space there’s no easy way to get rid of the waste heat from our electronics.” Doyle said. “In order to solve these problems, we heat synced our electronics to the water propellant tank, so that the waste heat from

CubeSat flight computers and on-board cameras

Photo courtesy Prof. Mason Peck

CubeSat flight computers and on-board cameras

the electronics could be drawn away. This keeps the water warm and our electronics from overheating. Our spacecraft is full of subtle tricks like that. We’re really trying to make the design clever but not complicated.”

Several aspects were considered when choosing water as a rocket propellant, including its accessibility, safety and price.

“Since water is such an effective propellant and is so common throughout the solar system, future spacecraft could land, gather water and go on to other planets.” Doyle said.

Peck added that safety must be a central concern of any such mission.

“In my opinion, it’s the most obvious propellant to use. Water is about as non-toxic as liquids get,” Peck said. ” Even what they call green propellant, which is a modern concept for low toxicity propellant is not that safe.”

One of Doyle’s most memorable experiences while working on the CubeSat was when he and his team found an interesting way to solve a particularly challenging problem.

“We needed some way to study the spacecraft while it was in microgravity, or free fall,” Doyle said. “What we decided to do was take a pottery wheel and attach the spacecraft to it with an electromagnet. We hung that upside down over a cushioned pit and dropped the spacecraft while it was spinning. It was such a bizarre approach to what we thought was a simple problem.”

The team’s passion for advancing space science is evident. While the Cislunar Explorers team is competing in NASA’s Cube Quest Challenge Tournament, which inspired the project and awards $5.5 million to the winning team, they readily share their findings with others.

“Democratization of information is a key feature of this project. All the designs, all the software, it’s all online. It’s all free,” Peck said. “So even though we’re in a competition, we are sharing our discoveries with the world. If we’re successful in this, anyone who wants to build a water-powered spacecraft could do that.”

As an experienced professor of aerospace engineering, Peck shared a few words of wisdom with budding engineers.

“Care about what you work on,” Peck said. “You have this rare opportunity to really make an impact. If you care about it, that’s a key ingredient for people to be successful in their careers. In the long term, if you really care about what you’re doing, there are really no limits for an engineering degree.”

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