“A 1950s space propulsion project using nuclear pulse technology discussed as a superior alternative to chemical rockets.”

“A 1950s-60s project exploring spacecraft propelled by nuclear explosions.”

“The codename for what was initially planned to be GPT-5, but was released as GPT-4.5 due to not meeting expectations.”

“OpenAI's internal effort to build GPT-5, which ultimately failed to meet performance targets.”