NASA to Research Antimatter Rocket

Fraser Cain writes "One of the dozen technologies selected by NASA's Institute for Advanced Concepts (NIAC) this year is Positronics Research's ideas for an antimatter rocket engine. Instead of 3100 kg of propellant on board Cassini, the spacecraft could get by with just 310 micrograms of electrons and positrons. Of course, making the antimatter can be expensive."

Comments

But, if I give'r any more she'll explode!

[beldraen]

Is everything shooting along while power generation creeps?

Work out the chemistry on it. The simple truth is that unless there is a fundamental change in energy density of chemical reactions, there just isn't a lot more to ask of chemical storage. That's why there is the shift towards "power generation." This is really just a fancy term for changing from where there is a chemo-eletrical differential (i.e. positive/negative sides) to actively causing a chemical reaction that provides electricity; however, there are two problems with this approach. First, it is usually easier to ask the device to use less power. Second, power generation at a minimum produces heat, sometimes violently and excessively. Batteries are nice because they are generally quite safe, reliable, and (most importantly) currently mass-produced.

On a side note, super atoms seem to be a possibility on "rewriting" our understanding on chemical reactions.

Re:But, if I give'r any more she'll explode!

[Rei]

Yeah, chemical advances are pretty much a dead-end (although there may still be *some* improvement left to go - for example, alane (stabilized aluminum hydride) hybrid rockets) but there's a long way to go before we can just deal with things like antimatter rockets.

Just ignoring all propulsion-creation issues (you can't just pump the two things together in a reaction chamber, and most of the emitted energy is gamma), when you see statements like this:

Instead of 3100 kg of propellant on board Cassini, the spacecraft could get by with just 310 micrograms of electrons and positrons.

It sounds great until you realize that, with conventional technology, those 310 micrograms would require a penning trap weighing hundreds of tons (at best) to store them. We need *far* better storage density in addition to far more efficient antimatter generation.

Far more near-term is antimatter-catalyzed microfission and microfusion (where you use antimatter to start a fission or fusion reaction in a tiny fuel pellet). For non-antimatter based high ISP propulsion, there are lots of neat ideas - to name a few, solar and magnetic sails, magnetohydrodynamic propulsion, fission fragment rockets, Orion and its successor Medusa, photonic rockets, and one of my favorites, nuclear saltwater rockets (you store an concentrated aqueous uranium or plutonium salt in capillaries, and inject it into a reaction chamber where it reaches critical mass and flies out the back at extreme speeds)

Expensive isnt even beginning to descripe it....

[imsabbel]

Without so much more technological breakthroughts (who will of course make that whole project pointless, because totally new options would arise), building a antimatter rocket will be impossible.

First: containment-> Its hard getting long livetimes in a nice good storage ring that doesnt suffer massive accelerations and other nasty stuff launching from earth brings with itself.

Second: containment part two: To power it, you would need a energy source of such capacity that could feed an ion drive or equivalent just fine without the need for antimatter.

Third: containment part three: if it fails it will give the a real nice flash. ok, with such a small one this doesnt matter (a normal rocked exploding is also devastating, but a bigger one would be like a nuke on steroids).

Fourth: Production of anitmatter: current efficiency of antimatter creation is somewhere around absolute zero... dont know the the exact numbers (the article was a few years old), but with current technology it could very well take the energy production of the whole USA to create that much anitmatter... for a year or so...

All those points dont mean that it wont be possible (or even desirable) to build an antimatter engine, but the needed advancements are THAT far away, that every kind of basic studies now are pointless.

More than that...

[ControlFreal]

The upper end of your scale, 5 kg, amounts to E = m * c^2 = 5 * 9e+16 = 4e+17 Joules.

The Russian Tsar Bomba ---the World's largest nuclear weapon ever detonated on Earth--- yielded 50 Megatons of energy, or about 50e6 * 4e9 = 2e+17 Joules.

That bomb didn't kill us, so 5 kg of antimatter won't kill us all.

To put things in perspective, the Hiroshima bomb (15 kton) destroyed about 1.5 grams of matter. The Tsuami quake on the Pacific, last year, yielded about 30 Gigaton, or 6.4e+19 Joules. That amounts to about 600 to 700 kg of destroyed matter.