Thursday, July 6, 2017

A Plasma Rocket Engine May Get Us To Mars In 40 Days (Elon Musk, Are You Listening?)

Born the son of Chinese and Costa Rican parents and with just $50 in his pocket, Franklin Chang Diaz came to the U.S. to do his undergraduate studies at the University of Connecticut and later, his graduate work at the Massachusetts Institute of Technology. At the time, the 18-year-old had no idea that he would ever fly in space, let alone set a world mark for it. He is now co-record holder for the number of visits to the International Space Station -- seven Space Shuttle flights from 1986 to 2002 -- tied with Jerry Ross.

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. Theoretically, the engine could cut time for manned missions to Mars to as little as 39 days versus the eight months it would take using today’s chemical rockets. NASA has shown interest. 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. "When you open a hole at one end, the gas squirts out and the rocket goes the other way. The hotter the stuff in the canister, the higher the speed it escapes and the faster the rocket goes. But if it’s too hot, it melts the canister."

So what do you do to counter that? "When gas gets above 10,000 degrees, it changes to plasma -- an electrically charged soup of particles. And these particles can be held together by a magnetic field. The magnetic field becomes the canister, and there is no limit to how hot you can make the plasma."

As for the added speed needed to reach Mars in 39 days, Chang Diaz references the Apollo astronauts who, on their trips to the moon, hit a maximum of about seven miles per second. "Remember, you are accelerating the first half of the journey -- the other half you’re slowing so you will reach Mars but not pass it," says Chang Diaz. "The top speed with respect to the sun would be about 32 mps. But that requires a nuclear power source to heat the plasma to the proper temperature."

And that, of course, is why the plasma engine is controversial. "People are afraid of nuclear power. Chernobyl, Three Mile Island, Fukushima -- it is a little misunderstood. But if humans are truly going to explore space, we eventually will have to come to grips with the concept."

SpaceX CEO Elon Musk, another big Mars proponent, is one who is a bit skeptical. "So people like Franklin -- basically it’s a very interesting ion engine he’s got there, but it requires a big nuclear reactor," says Musk. "The ion engine is going to help a little bit, but not a lot in the absence of a big nuclear reactor." And that, says Musk, requires the expense of getting that kind of added weight into space. Musk has also cited worries about rockets carrying nuclear materials failing, with radioactive debris possibly entering back into the earth's atmosphere.

Chang Diaz has very much lived the American Dream. "I am the product of two cultures. Costa Rica gave me the foundation and the U.S. gave me the opportunity. I wouldn’t have been able to take advantage of the opportunity if I didn’t have the foundation. I came to this country alone in 1968 with just $50 in my pocket."

Chang Diaz, a 2012 inductee into the NASA Astronaut Hall of Fame, says that space travel never got boring for him, even on his later flights. "It’s like when you learn to taste some exotic new dish," he says. "The first time, you like it. The second time, you discover a bit more of the taste and learn to appreciate all the nuances and dimensions. So I think you live it much more fully after you become accustomed to it."