Solar Sail dupe with atompunk design, TFINER identified

In an exciting development, NASA's Innovative Advanced Concepts (NIAC) office has advanced the Thin-Film Nuclear Engine Rocket (TFINER) proposal into a Phase II study. The study will be carried out by the Charles Stark Draper Laboratory, Inc.

TFINER is a proposed space propulsion method that uses a thin film of nuclear material as its propulsion source. The nuclear material releases alpha particles, which provide the reaction mass for propulsion. The sail of TFINER is a 9.5 um thin film on a 35 um beryllium back-plane.

The focus of TFINER is not on achieving speeds that are a fraction of the speed of light, but rather on a terminal/cruising velocity of approximately 100 km/s. This velocity is significant, as it would allow for interstellar travel in the long run.

The proposal for TFINER references extra-solar comets like Oumuamua as potential flyby targets. These comets, travelling at high speeds, could provide a natural gravitational slingshot effect to boost the spacecraft's velocity even further.

One of the challenges with TFINER is the need for shielding or long shrouds for the payload. A reference design calls for 400 m cables for this purpose. Additionally, the decay products of TFINER are too short-lived to matter, and the thrust falls off after a few years due to the short half-life of Th-228 and Ra-228.

Despite these challenges, the alpha particles in TFINER travel at about 5% the speed of light, providing a significant amount of thrust. The specific impulse (ISP) of TFINER is an impressive 1.81 million seconds, one of the highest ever recorded for a space propulsion system.

The future of TFINER looks promising. Future work includes combining the concept with an actual solar sail for maximum possible delta-V from an Oberth-effect sundive. This could potentially make TFINER a more viable option for interstellar travel.

TFINER has been summarised on Centauri Dreams by Paul Gilster, a well-known space exploration journalist. While TFINER is not ideal for a quick trip to Alpha Centauri, it represents a significant step forward in our quest to explore the stars.