If that isn't enough Chang Diaz, retired from NASA since 2005, works at his Houston, TX-based Ad Astra Rocket Co. developing a revolutionary plasma engine. In his new book, "To Mars and Beyond, Fast" (Springer Books, June 2017, co-written with Erik Seedhouse) Chang Diaz discusses the high concept in layman's terms. In 2015, it gave Chang Diaz a three-year, $9-million development contract. "A rocket engine is a canister holding high-pressure gas," Chang Diaz, 67, explains. And that, of course, is why the plasma engine is controversial.

Source: Forbes July 06, 2017 14:15 UTC