Propulsion

What is propulsion?

Propulsion is the subsystem that will take the spacecraft to Saturn. Once the spacecraft is in orbit, the propulsion system will insert it into a transfer orbit and then orbit around the Saturn. The propulsion system works based on Newton's Third Law; every reaction has an equal and opposite reaction. As the propulsion system pushes hot gases out of one end of the rocket, it moves in the opposite direction. The complication comes in finding the best, most efficient way to move hot gas out of the novel.

Liquid Rocket Engines

Liquid Rocket engines rely on the chemical energy found in the fuel and oxidizer. Both the fuel and the oxidizer, usually liquid oxygen, are pumped from the fuel tanks, through the fuel injector, and into the combustion chamber where it it burned and exits the nozzle, propelling the rocket forward.

Ion Propulsion

Ion propulsion uses electricity to heat up and ionize a gas, usually xenon, to push the spacecraft forward. This leads to higher specific impulse, and the spacecraft only needs to carry one fuel.

Thermonuclear Propulsion

Thermonuclear Propulsion uses the heat from nuclear fission to heat the propellant. The fuel then exits the nozzle. This is a very similar design to ion propulsion, but uses nuclear fission instead.

Solid Rocket Engines

Solid Rocket Engines use a solid propellant and oxidizer. This makes the design of the engine much more simple than the other 3 engines. It has a very high thrust, but low specific impulse.

Trade Study

This is a comparison of the various propulsion systems. Specific impulse is weighted so highly, at 40%, because in such a long duration mission like ours, efficiency is essential. Previous missions are also weighted highly because these can be used to develop better propulsion systems. High thrust is needed to shorten the mission duration, as higher thrust can get to the desired orbit. Complexity is also an important measure as a more complex engine has more opportunities for failure during the mission.

Nuclear Propulsion

The Tiger's Ebb Mission would be a perfect mission to prove out this technology. Nuclear propulsion promises great specific impulse and thrust, both vital characteristics needed in long duration missions. Nuclear propulsion could help future missions go further and faster than ever before.

How to Control a Nuclear Engine

The valves and pumps that feed the hydrogen around the nuclear reactor will turn off to turn off the engine. But, the nuclear reactor will keep running. To limit the decay, there are control drums around the reactor. Half of the drum has a reflector, to increase the amount of particles colliding, increasing the heat in the reactor when it is in use.

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