The science fiction author Isaac Asimov wrote a series of novels and short stories about robots. Besides inventing the three laws of robotics, he also came up with the idea of the robots having brains running on positrons. He called these positronic brains. In Star Trek, the Next Generation, in homage to Asimov, the android character, Data, played by the actor Brent Spiner, is described as having a positronic brain.
Despite this fictional usage of “positronic,” the positrons that supposedly kept Data functioning are not fictional. They are quite real. What are they? They are the antimatter equivalent of electrons. And yes, despite the use that Star Trek made of antimatter to power its warp engines, antimatter, too, is quite real.
The NASA Institute for Advanced Concepts (NIAC) is funding a team of researchers working on a new design for an antimatter-powered spaceship that makes use of positrons. Why positrons for a spacedrive?
Massive power in a very small space. When antimatter comes into contact with matter, both are annihilated in a flash of energy. It is a complete, one hundred percent conversion of matter into energy, unlike the nuclear reactions of an atom bombs, where only a paltry three percent of the bomb’s total mass is converted to energy. Antimatter-matter reactions are considerably more powerful than any nuclear bomb.
So, while tons of chemical fuel would be needed to propel a human mission to Mars, and hundreds of pounds of nuclear material would be needed for the same trip, just tens of milligrams of antimatter would do the same job. A milligram is very small. A single M&M weighs about one thousand milligrams. Thus, it would take only a tine fraction of an M&M’s worth of antimatter to power a human crewed spaceship to Mars.
Definitely something worth looking into.
Admittedly, there are some problems with antimatter. For instance, most antimatter that has been produced is in the form of antiprotons. When these antiprotons react with matter, the energy releases massive amounts of dangerous gamma rays, which are deadly. Any spaceship using antiprotons for fuel would need a large amount of very heavy shielding in order to protect a human crew from being killed.
That’s where positrons come in. Positrons are anti-electrons, and when they react with matter, they do not produce the levels of deadly gamma radiation anti-protons would. So positrons are safer and save a lot of liftoff weight.
The other, more significant problem with antimatter is the difficulty of making the stuff. To produce enough positrons to power a spaceship to Mars would cost around 250 million dollars.
But put that in perspective. The distance from Earth to Mars is between 36 million and 250 million miles, so that makes the per mile fuel cost for a round trip to Mars somewhere between fifty cents and three and a half dollars. A bit more than current gasoline prices, but not quite as scary sounding.
Of course, the 250 million dollar cost of producing the positron fuel is based on current production methods. One suspects that if some effort were put into it, engineers could find a way to do it for less.
The big advantage of a positron powered spaceship is safety. It reduces the time of travel to Mars by a considerable margin. People could get to Mars could in as short as 45 days (versus 180 days using a nuclear powered ship), thus reducing the exposure of the crew to the debilitating effects of zero gravity. Even better, it would limit the crew’s exposure to deadly radiation from the sun (radiation that our atmosphere mostly shields us from on Earth, aside from the possibility of sunburn). Also, the positron powered ship would not have any radioactive waste products to worry about, unlike a nuclear powered ship, and there would be no radiation hazard at all from any mishaps during launch. The positron reactor would also be much less complicated than a nuclear reactor, and thus reliability would be greater: less to go wrong with it.
It is good that NASA is looking into alternate means of powering its spaceships, and rather exciting to think that spaceships in the not too distant future may have the same power source that the fictional Starship Enterprise enjoyed. And of course if Harold “Sonny” White’s experiments work out, the antimatter drive NASA’s working on might wind up powering his warp engine.