NASA Tests Dual Mode Propulsion CubeSat Ahead of Launch

Spacecraft propulsion traditionally relies on volatile fuels and separate, bulky systems for different types of maneuvering in space. NASA is working to change that paradigm. Engineers at NASA’s Marshall Space Flight Center in Huntsville, Alabama, recently completed a rigorous series of environmental and physical tests on a new small satellite designed to make spaceflight safer and more efficient. The ASCENT (Advanced Spacecraft Energetic Non-Toxic) Propulsion Dual Mode mission is a flight demonstration of a spacecraft about the size of a large shoebox, and it will test a single, integrated propulsion system that uses a common fuel tank to feed two different types of engines.

Typically, spacecraft carry two separate propulsion systems to navigate: a high-thrust chemical system for rapid movements like entering orbit, and a low-thrust electric system for highly efficient, slow maneuvers like maintaining a position. This requires multiple fuel tanks and heavy plumbing, which eats up valuable space and weight. The ASCENT spacecraft uses a single non-toxic propellant called ASCENT. By feeding both a high-thrust combustion engine and low-thrust electrospray thrusters from one central tank, the spacecraft saves critical mass and volume. For future missions, this means more room for scientific instruments and the ability to launch on smaller, less expensive rockets.

Bringing this concept to flight requires a nationwide collaborative effort. NASA Marshall manages the mission, while the spacecraft relies on electrospray thrusters developed by the Massachusetts Institute of Technology, a chemical propulsion module built by Plasma Processes, and a spacecraft bus integrated by the Georgia Institute of Technology. Nehemiah Williams, the demonstration’s project manager at NASA Marshall, said, 'There are a lot of odds and ends, and a lot of small challenges and some big ones. But ensuring the functionality of the propulsion system across all these different teams is what makes the mission successful.' Before a spacecraft can safely operate in the harsh environment of low Earth orbit, it must pass a battery of tests on the ground.

Over the past few months, the engineering team at Marshall has put the flight hardware through its paces inside the center’s Small Spacecraft Servicing and Integration Lab. To verify the integrity of the unified propulsion system, the team conducted extensive leak testing. Engineers performed a pressurized helium leak test of the spacecraft inside a vacuum chamber to ensure the integrity of the spacecraft’s seals, successfully proving those seals were working as intended. Because the system shares a single tank of ASCENT propellant to feed two different thruster types, ensuring that the fuel lines and valves are perfectly sealed is vital for mission safety and success. The team also subjected the spacecraft to thermal vacuum testing, simulating space’s lack of air and extreme temperatures.

Together, the leak and thermal-vacuum checks represent key pre-flight milestones for the shoebox-sized demonstration. If the flight demonstration succeeds, the dual-mode design could make future spacecraft safer and more efficient while freeing up mass and volume for payloads and smaller launch vehicles.