Solar Sail Design Akin to Atompunk Style, Crafted by TFINER

In a significant step forward for space exploration, NASA's Innovative Advanced Concepts (NIAC) programme has advanced the Thin-Film Nuclear Engine Rocket Engine (TFINER) to a Phase II study. Dr. Maria Schneider, the lead researcher for the TFINER project, is spearheading this innovative endeavour.

TFINER, a proposed space propulsion method, focuses on potential flyby targets, such as extra-solar comets like Oumuamua. The engine uses a thin film of nuclear material for propulsion, specifically a 9.5 um thin film on a 35 um beryllium back-plane. This film is designed to harness the energy from the decay products of Thorium-228 or Radium-228, which provide the reaction mass in TFINER.

The half-life of Th-228 is 1.91 years, and Ra-228 is 5.74 years, causing the thrust to fall off over time. However, the engine's design allows for some degree of thrust-vectoring by playing out or reeling in the cables, which could help maintain control during long missions.

One of the key features of TFINER is its potential performance. The engine could reach a terminal/cruising velocity of ~100 km/s, providing a significant boost for interstellar missions. The specific impulse (ISP) of TFINER is an impressive 1.81 million seconds, making it one of the most efficient space propulsion methods under development.

Alpha particles from Thorium-228 or Radium-228 travel at about 5% the speed of light. Most of these emissions aim roughly normal to the surface, making it out of the 9.5 um thin film. This design ensures a safe and effective propulsion system.

Future work for TFINER includes the idea of combining it with a solar sail for maximum possible delta-V from an Oberth-effect sundive. This would allow for even greater control and efficiency during missions.

The TFINER concept has garnered attention, with Paul Gilster summarising it on Centauri Dreams. Another intriguing aspect of the TFINER proposal is the focus on the Sun's gravitational lens effect. The Sun's gravitational lens effect results in a focus that is a line, not a point, which could provide unique opportunities for astronomical observations.

The Phase II study will involve actual hardware, a 1 square centimeter demonstrator, to further test and refine the TFINER concept. With this demonstrator, we can get a better understanding of how the engine performs in real-world conditions, bringing us one step closer to interstellar travel.