two grams of your finest antimatter please…

A new way of creating positrons hints at a potential shortcut towards antimatter engines. But we're still a long way off from such spacecraft...
insterstellar spacecraft concept

It’s the most dangerous, explosive, and expensive substance in the universe, valued at roughly $60 trillion per gram, and it offers great promise in expanding our reach into space. We’re talking about antimatter of course, and despite how exotic and rare of a substance it is, we know where it occurs naturally and can even make it in a lab and trap it for later use. Unlike plasma rockets and ion drives, antimatter offers raw, explosive energy that could seriously increase how much we can launch into orbit and beyond, make SSTO far more feasible, and even allow us to build relativistic rockets. But for all its potential benefits, this bizarre substance just can’t be made in industrial quantities for the foreseeable future and is so unforgiving, using it as a fuel could be an exercise in extreme risk taking, requiring redundant backup systems, radiation shields and escape pods.

Normally, this would be the end for most posts dealing with antimatter as a potential fuel or a catalyst for new generations of spacecraft. However, antimatter does have a couple of things going for it. When we talk about industrial quantities of something, we’re usually talking about tons. With antimatter, we’re talking about grams and maybe even a few kilograms for a relativistic rocket targeting another solar system. That’s not totally out of the question from a technical standpoint since today, we know how to generate more than 100 billion particles of the stuff using a laser and a thin sheet of gold and with an efficient enough capture mechanism, we could make enough antimatter to add a lot more kick to modern rocket designs. On top of that, we can build reliable containment systems which will be able to keep the antimatter stored until it’s needed, so production, capture, and containment are all perfectly plausible and use technology we already have. It’s not unreasonable to think that sometime in the near future, someone will use a few hundred milligrams of anti-hydrogen or a few grams of positrons to send a manned mission to Mars or beyond. But of course, there are a few catches.

Even the most effective methods of making antimatter we know of today would need years to produce enough of if to fuel a single mission and use powerful lasers and containment chambers which you can’t just buy at a local hardware store and require teams of specialists to build and maintain. That’s going to keep the price of antimatter extremely high and unaffordable for any space agency for the foreseeable future. Not only that, but anti-hydrogen and positrons are extremely explosive and produce a shower of gamma rays when they touch even the tiniest trace of normal matter. Should their containment chamber lose power for even a millisecond, there’s going to be a very energetic, unplanned explosion emitting ionizing radiation that could kill astronauts or knock out the craft’s electronics. These effects could be countered by heavy radiation shields, but there’s a limit to how thick you can make your radiation shield before the craft is too heavy to benefit from an antimatter additive. And this is beside all the gamma rays the matter-antimatter reactions are going to put out anyway as part of the ship’s normal operations. The more energetic the blasts, the faster the craft, but the more radiation and risks to crew members which is pretty disappointing for antimatter enthusiasts.

Hopefully, someday in the future we’ll figure out how to manage antimatter and have the required economies of scale to produce a few hundreds grams of it per year but to do that, scientists and engineers need funds to conduct a lot of tests and run hundreds of experiments. The big question is who would be willing to provide a big enough sources of cash to enable this kind of research, knowing full well it would take decades to see an actual antimatter powered spaceflight soar into orbit and motivated primarily by a desire to improve the world for the far future rather than turning a profit in three to five years. Although you never know what spin-offs from such experiments might turn out to be highly lucrative and start delivering a return on investment within just a few years. Science at the cutting edge is unpredictable and filled with all sorts of interesting possibilities.

# tech // antimatter / antimatter propulsion / research


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