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New Antimatter Engine Design Sunday, October 29, 2006 - Iddo Genuth Home >> Articles >> Space   
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A team of scientists is currently working with NASA to develop a new form of space propulsion technology based on positrons. This revolutionary antimatter engine will require only a few milligrams of positrons to send a spaceship to Mars. Facing many hurdles along the way, this is the first time some of the real problems of building a real antimatter engine are being confronted.
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Nuclear propulsion systems for rockets have been studied by NASA since the early 1960's under the Nuclear Engine for Rocket Vehicle Application (NERVA) program, subsequently cancelled in 1972. In 2003, the nuclear space propulsion idea was revived by the Prometheus Project still under development. Although the nuclear propulsion option looks like a prime candidate for the future Mars mission, its disadvantages (mainly extreme radioactivity) led people like Dr. Gerald A. Smith, founder of Positronics Research in Santa Fe, New Mexico, to suggest a bold new alternative – antimatter. First predicted by the British physicist Paul Dirac in 1928 (and experimentally confirmed 4 years), antimatter is comprised of antiparticles that annihilate when they come in contact with ordinary particles, producing a burst of energy in the form of energetic photons. NASA's Institute for Advanced Concepts (NIAC) recently funded Dr. Smith's research to examine the potential applications of antimatter as a fuel for a manned mission to Mars. Dr. Smith and his team at Positronics Research suggested to NASA three possible propulsion concepts, all based on positrons (or anti-electrons).
Interview with Positronics ResearchTFOT recently conducted an interview with Dr. Smith to learn more about the potential of positron-based space propulsion systems.Q: Were you the first to come up with the idea for a positron-based propulsion system?
Q: You mentioned that positrons emit less powerful gamma rays than antiprotons. Is the energy produced by positrons still sufficient for a useful propulsion system? The low energy of the positron annihilation gamma rays make these very easy to contain and turn into propulsive energy. But, it takes 1836 times more positrons to get the same amount of energy as one antiproton. The antiproton annihilation energy is very hard to contain and turn into propulsive energy. In fact, the only way I know to use antiprotons is to make them create nuclear fission reactions in materials like uranium, which results in one of the nasty sides of nuclear fission, namely the presence of radioactive isotopes created by the engine. Q: Can the positron engine perform liftoff or is it more like an ion engine, which can only be used in space? A: Yes to the first question, and no to the second question. But, for many practical reasons we prefer for the first trials to assemble the spacecraft in LEO (low-earth orbit) and power it with positrons from LEO into space. Q: Is this mainly a safety issue or are there other considerations? A: It is partly a safety issue and partly an economic issue. 10 milligrams (mg) (a Mars mission) of positrons contains the energy of 428 tons of TNT. Or, to put it another way, 10 mg of positrons contains the energy of 23 external fuel tanks on the Space Shuttle. We would want to make sure that we know how to handle the positrons with utter confidence before attempting a liftoff from Earth. This would come with time. (Recall the early attempts to launch rockets from Earth in the 1920-1940's with all the mishaps.) The other reason is economy. It takes a lot of energy to lift the spacecraft into LEO. We know how to do this with chemical fuels. It is much cheaper to put the parts of the spacecraft into LEO with chemical fuels than lift the whole thing into LEO using positrons. Q: Would you describe in a few words the three positron-based propulsion concepts you have come up with, how they work, and what their main advantages and disadvantages are? A: The three positron-based propulsion systems we suggested to NIAC were:
Q: How do you intend to deal with the two major problems of antimatter propulsion systems - the creation of antimatter and finding a way to store it for long periods of time? You cannot hold 10 mg of bare positrons in a magnetic trap. The "space charge" forces are enormous and the "positron plasma" blows itself apart. But, with electrically neutral atoms containing positrons, this is not a problem. Our work with positronium is on-going. My sponsors implore me to not discuss details at this time. Suffice it to say we have had some very encouraging results.
Q: What is the time frame for a possible positron-based mission to Mars? A: A launch to Mars is conceived for the 2030 time frame. |
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| Interesting - I never thought it would be possible in the near future to create an antimatter engine. However, this seems to be remarkably similar one would find in a science fiction novel. Why not create a nuclear propulsion engine similar to the canceled Project Orion? The dangers of nuclear fallout ought to be about equal to the dangers of an unproven positron engine, or, if it isn't, nuclear propulsion systems could be sent to geosychronous orbit and then take off. It has the added advantage of already being thoroughly researched, and thus could be realized far more quickly than any antimatter engine. And, straying from my earlier subject, the Orion Crew Exploration Vehicle is currently under design by NASA. I find it unlikely that such a speculative engine as one using positrons would be used to travel to Mars (It's only like 1/3 AU). We should use positron engines to travel to areas outside of the Solar System | |||
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| Although the idea of the positron engin is exciting, it is not possible in the near future, due to a lack of antimatter. It would tak CERN twenty billion years to create enough antimatter to feul a mission to Mars. |
