Next Stop: Alpha Centauri
This from Prof R on a potential (real) warp drive reminded me of a subject I’ve been meaning to post on for a while: anti-matter !
Yeah, I’m the kinda guy who thinks things like “I really should post about anti-matter soon.” Learn to live with it; otherwise hey, the back button’s right at the top of the screen, buddy.
There’s an occupational hazard of being a devout science-fiction reader. Which is that in your mind, you build up a collection of technologies and milestones which exist in a a grey area where you have to stop and think: “Is that real yet? Or did I just read that in Baxter’s latest?”
The problem is worse if you focus on writers who actually do good science (see the Creative Dream Team if you’re looking for a list). Growing up on Heinlein, I continually had to remind myself that no, we don’t have rejuvination treatments for life extension yet, and no, there is not a former prison colony called Luna City on the moon.
Anyway, to get to the point: anti-matter has been floating in that bucket in my mind for years. But recently, doing some research, I stumbled across the fact that not only is anti-matter real (which I knew); not only has it actually been produced (which I suspected), but folks have actually got legitimate designs for spacecraft to be driven by it (which I had no idea).
The good folks at the Antimatter Space Propulsion group at Penn State University have developed designs for not one, but two different potential antimatter propulsion drives.
The first method is known as antiproton-catalyzed microfission/fusion (ACMF), uses very very very tiny amounts of antimatter to generate energy sufficient to trigger a fission reaction. This minimizes the amount of actual antimatter required as fuel — which is the major problem with any of these concepts, as our capacity to generate antimatter is very limited — and will be for some time. The Penn State team has designed not just the drive, but a spacecraft to use it, dubbed ICAN-II. It is shown in the top-right picture above, and the full description can be found in this PDF file.
So what could you do with ICAN-II? How about a manned mission to Mars? ICAN-II would allow a mission to be be launched in a window that occurs every two years for a 90-day round trip to Mars, with a 30-day stay at the planet itself. Feel like a longer drive? Try Jupiter: ICAN-II will get you there and back in eighteen months, and give you 90 days to enjoy the sites while you’re there. Really need to get away from it all? Pluto is a mere three year (one-way) trip away.
All that’s fine and good, but only weenies just want to stay within our own Solar System. (“The meek shall inherit the Earth… the rest of us are going to the stars.”) And sadly, even ICAN-II doesn’t provide a powerful enough drive to get you to anywhere worth going outside our system before you’re, well, dead.
But no worries: the Penn State folks have got it covered. First, enter AIMstar, a spacecraft based on Antiproton Initiated Microfission/fusion (AIM). This design uses antimatter to spark a fusion reaction, generating a larger specific impulse and enabling longer voyages. It’s not all good news, though: AIMstar is designed as an unmanned craft, and will still take 50 years to get to the Oort cloud (at 10,000 AU).
Future designs, though, could bring Alpha Centauri into reach for manned missions. “Plasma Core” and “Beamed Core” drive designs — which come closer to the direct “antimatter+matter = large boom” design of science fiction, make starships capable of reaching up to 40% of the speed of light feasible — enabling a trip to Alpha Centauri in a long-but-feasible 10 years.
The problem, though, is that beamed core engines require huge amounts of anti-matter: well beyond our production capabilities for at least the next few decades, unless an unforseen breakthrough occurs. The Penn State team provides a throrough review of our (and by our, I mean the planet Earth) anti-matter production capabilities for the near future, which assesses not just the raw mass being produced, but the actual cost (real dollars!) to do so. It also includes a very very spiffy graph, which I reproduce as the final image here, which shows exactly how much antimatter mass is required for various voyages using the different propulsion methods being discussed. 
One final thought, which is somewhat of a downer: antimatter is, without exaggeration, the most dangerous substance ever created by man. I think that’s a truism, when you consider that the energy released by a antimatter-matter reaction is near total. And given our current climate of concern around securing nuclear and biological materials… I think you see where I’m going.
The good news is, the quantities of antimatter being produced today are, to my understanding, nowhere near anything that could be used as a weapon. But eventually, they will be. And antimatter weapons come with a particularly nasty attribute: if there’s a nuclear missile coming at you, you can shoot it down with conventional weapons and feel reasonably assured that there won’t be a nuclear reaction.
Not so with antimatter warheads. ‘Cause if you destroy the containment system keeping the antimatter in place with that conventional warhead, there’s going to be a reaction — whether it reacts with the material in the warhead designed for that purpose, or with the ground as it crashes down after your takedown.
Anyway, sorry to end on a depressing note, but we will have to think about a way to produce this stuff without it being an easy target for nutcases, sooner or later.
Trans-orbital antimatter production facilities, anyone?
Final Note: The work done at Penn State has now apparently been taken up by a commercial entity; a company called Positronics Research. The initial website I provided as the first link to the Penn State team’s above is a sub-page of Positronic’s site; however, if you wish to see the actual Penn State page (which appears to be orphaned and no longer being updated) you can view it here.
Final disclaimer: I am not a spaceflight expert by any means, and I have not fact-checked the sources above in any real way. They could, I suppose, be complete nonsense, but I’m assuming that Penn State keeps at least a slight eye on what their professors publish. And it is also worth noting that money has become involved here with the introduction of Positronics Research: which on the one hand suggests that somebody thinks these ideas are credible enough to spend money on, but on the other hand should lead us to consider the information with the skepticism that we view any presentation by someone with a commercial interest at stake. I would, therefore, welcome any pointers to additional info and/or opposing viewpoints on the feasability of the Penn State team’s work, or any other research in this field.