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If a spacecraft was designed to propel itself using the annihilation of matter and antimatter, what potential dangers would this create and how could they be circumvented or at least prepared for?

Could there be more risks than modern rockets have now?

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  • $\begingroup$ Hi, Antonio! Welcome to Space Ex SE. Could you please explain why your question is different than this one about antimatter propulsion? If your question is specifically about the engineering behind such a propulsion system, any answer we could give you would be speculation - if that's what you're after, you may have better luck on Worldbuilding SE. $\endgroup$
    – Bear
    Dec 14, 2016 at 14:16
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    $\begingroup$ @kekenkenka That question is about whether antimatter can be used for propulsion. This one is about the dangers. The question might need some work, but I think we could talk about the theoretical dangers of antimatter without getting bogged down in speculative engineering. $\endgroup$
    – called2voyage
    Dec 14, 2016 at 14:49
  • $\begingroup$ I would agree with this being a highly speculative question. Very little anti-matter has been produced to-date, far less than enough for any useful purpose, or even enough to call for solutions to the problems of storage and handling. $\endgroup$
    – Anthony X
    Dec 19, 2016 at 20:53

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This is essentially an engineering question. Dangers, or risks as you'd typically call them in engineering, have two aspects: probability and outcome. Something can be a high risk because of a high probability, or because of a serious outcome.

In the case of anti-matter, any significant containment failure would result in a catastrophic loss, so it's an important risk regardless of probability. The main reason for this is that the amount of energy on even a small containment failure released is very high, which will likely lead to the loss of the whole containment system, and thus the instant release of all energy on-board. And this release will be in a barrage of high-energy radiation, some of which itself will be anti-matter (fast positrons).

That said, you probably can't entire eliminate all leakage. There will be the occasional atom escaping the containment, and violently reacting. You'll need a secondary liner which should survive the duration of the trip; this is very much sacrificial. The main goal is to handle the secondary radiation; it should harm neither the confinement nor the ship itself, all the while being lightweight.

This would be true even if we somehow could manage to store the antimatter outside the actual spacecraft. This isn't easy, but we might be able to keep it confined just outside the ship, in the near vacuum of space. Still, that would be close to the ship, and probably close to half the anti-matter escaping confinement would still hit the hull. But that's OK, the hull was designed for that anyway.

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The major reason why modern rockets have not implemented a matter-antimatter propulsion system is because of the dangers that antimatter and its annihilation with matter pose.

Some of the antimatter problems are:

  1. Storage: As we know the storage of antimatter is very difficult and cumbersome. Its storage is energy consuming which will make the rocket more heavier. This will make it impractical to have a rocket with antimatter. Even if a speck of antimatter leaks it can cause severe damage to the rocket and its crew (if any).

  2. Matter-antimatter annihilation: The annihilation of 1 kg of both matter and antimatter will release energy in the range of 43 megatons of TNT. This is a significant amount of energy and it is also required to be directed in the correct direction for proper propulsion to be achieved.

To address the above problems we must devise a renewable energy source and an efficient way to store antimatter and learn how to correctly direct the resulting energy burst.

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    $\begingroup$ A possibly even more 'major' reason is that we don't have any antimatter. $\endgroup$ Dec 14, 2016 at 19:21
  • $\begingroup$ Antimatter can be created with a particle accelerator like the one in CERN @OrganicMarble. $\endgroup$ Dec 15, 2016 at 7:49
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    $\begingroup$ Yes; to say that "we don't have any antimatter" is a bit of a misnomer. However, I believe that the point @OrganicMarble is making is more like "making antimatter is very, very, very difficult, and we haven't made very much of it" -- which is a valid issue in the context of matter/antimatter propulsion, though perhaps not directly related to its dangers or mitigative strategies for those dangers. $\endgroup$
    – user
    Dec 15, 2016 at 16:01
  • $\begingroup$ We've made a lot of antimatter; the problem is keeping it around long enough to do anything interesting with it. To create antimatter you need to smash regular matter together at very high energies; this means that the created antimatter is usually moving pretty fast as well (so-called "hot" antihydrogen), and so tends to smash into the walls of your experiment and annihilate. Slowing it down (making "cold" antihydrogen) is quite difficult; last I checked, the state-of-the-art for the storage of anti-hydrogen atoms was about 15 minutes. $\endgroup$ Dec 16, 2016 at 15:57
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    $\begingroup$ @MichaelSeifert -- We've made minuscule amounts of antimatter. From Antimatter to ion drives: NASA's plans for deep space propulsion, "if all of the antimatter ever created to date were annihilated at once, it wouldn’t be energetic enough to even boil a cup of tea." $\endgroup$ Dec 16, 2016 at 16:50
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While most people would be inclined to worry about handling and storage, the primary problems associated with using antimatter are: a) The high energy input (and thus cost) necessary for the production of macroscopic quantities of antimatter, b) The very low efficiency of antimatter production, requiring a long time for its accumulation also dissipating lots of heat, and c) handling and storage. At CERN, it is possible to create justfew hundred antihydrogen atoms and to store them for several minutes using a sophisticated magnetic vacuum trap. There may be as many dangers associated with scaling up production (a and b) as with storing and handling the product. Even assuming possibility to create macroscopic quantities of antimatter using its annihilation for spaceships propulsion creates a danger of strong irradiation as the main product of annihilations are energetic gammas which requires a heavy shielding for efficient protection of passangers.

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  • $\begingroup$ There was a load of articles around 2018 about plans to transport antimatter in vans (in sophisticated magnetic vacuum traps, as you say) but I guess that's still in progress. Anyway, I think your point is valid but your answer would be better with sources. Welcome to Space Exploration SE $\endgroup$
    – Erin Anne
    Mar 26 at 8:59
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    $\begingroup$ This doesn't answer the question, which is about the dangers, not the difficulties. $\endgroup$ Mar 26 at 11:58

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