Cornell team develops water-powered satellite for lunar orbit

From http://www.digitaljournal.com/tech-and-science/science/cornell-students-shoot-for-the-moon-with-water-propulsion/article/475310

A tiny satellite, about the size of a cereal box and powered by water, is in the running to become the first CubeSat to orbit the moon.

A Cornell University student team calling themselves Cislunar Explorers is developing the little orbiter as part of NASA’s Cube Quest Challenge, which is offering prizes totaling $5.5 million to teams that build small satellites known as CubeSats.
Cislunar was an apt choice for the team’s name because it means “between Earth and the moon,” because that is exactly where the winning team’s tint orbiters are headed. NASA says the teams can compete in either a Lunar Derby or the Deep Space Derby. Right now, the Cislunar team is in phase three of the four-phased ground tournament portion of the challenge.

Cislunar Explorers

They finished first in the phase two portion of the challenge earlier this year. If Cornell’s team finishes in the top three teams at the end of the tournament, their little CubeSat will be among the three orbiters launched in 2018 aboard NASA’s Exploration Mission-1 (EM-1).
“This has a very important goal, and that is to demonstrate that you can use water as a propellant,” Mason Peck, a mechanical and aerospace engineer at Cornell and leader of the team of graduate and undergraduate students, said, according to Space.com.

“Of course, we’d like to be the first CubeSat to orbit the moon,” he added, “but even if we don’t, if we can successfully demonstrate that water is all you need to travel in space, we’ve gone a long way toward achieving some important goals.”

In looking ahead to the possible use of water as a source of propulsion, a spacecraft powered by water would not need to rely on Earth resources to function. Instead, water could be obtained from space-bound water sources such as asteroids, say researchers.

Peck pointed out that a lot of the total mass sent into orbit today is in the form of rockets. “But what if we could use what’s already there? If we could do that, if we could refuel spacecraft while they’re already in space, that means that we could go farther, probably faster, probably accomplish a lot more, and we wouldn’t rely on Earth for supplies.”

Cornell’s CubeSat entry

Cislunar’s entry consists of two L-shaped sections that would split apart, with each piece heading for the moon’s atmosphere. In order to maintain stability, they will both spin while in orbit, using electricity to convert water into hydrogen and oxygen for fuel.
The fuels will eventually propel the two halves into a lunar orbit where pictures will be taken of the Sun, the moon and Earth, enabling the tiny orbiters to keep track of their navigation. This technology is called optical navigation
Fueling the CubeSats is a unique accomplishment

The fuel problem was handled brilliantly. Hydrogen and oxygen have been used as a propellant in the early days of space exploration, like in the upper stages of the Saturn V and the Apollo program. But the two gasses were stored separately as cryogenic liquids.

Cislunar Explorers

Not only did it necessitate storing the gasses separately, but hydrogen needs to be stored at very high pressures and very low temperatures. This requires pumps, pressure vessels and heavy insulation.

Instead, the Cislunar team is going to zap the water with electricity, overcoming the molecular bond and separating the liquid into a gaseous mixture that will readily combust. To keep the water from just floating around in the propellant tank, the team has the spacecraft spinning around the thruster, and like a centrifuge, the water is flung outward, helping to separate inert from electrolyzed propellant.

The Cube Quest Challenge is sponsored by NASA’s Space Technology Mission Directorate Centennial Challenges program. The challenges were initiated in 2005 to create interest in and directly involve the public in the process of advanced technology development.The challenges are open to independent inventors including small businesses, student groups and individuals.