Fast Human Missions to Mars Using Direct Fusion Drive with a Nuclear Thermal Stage

摘要

The Direct Fusion Drive (DFD) is a nuclear fusion engine concept that produces both thrust and electric power. It employs a field reversed configuration with an odd-parity rotating magnetic field heating system to heat the plasma to fusion temperatures. The engine uses deuterium and helium-3 as fuel and hydrogen that is heated in the scrape-off layer for thrust augmentation. In this way variable exhaust velocity and thrust is obtained. The exhaust velocity for a given power is limited by the physics of the engine so that low exhaust velocities (＜ 50 km/s), and high thrusts, cannot be achieved. Adding a nuclear thermal engine provides an improved mix of thrust and high exhaust velocity allowing for faster and more efficient missions than either technology can achieve alone. This paper presents the design of spacecraft for human missions to Mars. The mission is for two weeks in Mars orbit or on the surface.The mission uses NASA's Deep Space Habitat to house the crew, just to provide a payload mass. The mission uses a nuclear thermal engine to get through the Earth's radiation belts quickly. Using the nuclear thermal engine saves time and reduces the crew's exposure to radiation. The NTP also provides a high thrust abort option. The mission is almost a year for a two week stay. Longer stays allow for better return geometries and lower trip times. The paper includes a detailed design of the Direct Fusion Drive engine. The computation of the specific power for the engine is presented along with a full mass budget for the engine. The paper provides a conceptual design for the nuclear thermal engine and its integration into the vehicle.