Relativistic Rockets, Antimatter and More

by Paul Gilster on February 22, 2010

Interstellar theorist Richard Obousy (Baylor University) has some thoughts about William and Arthur Edelstein’s ideas on flight near the speed of light. As discussed in these pages on Friday, the Edelsteins, in a presentation delivered at the American Physical Society, had argued that a relativistic rocket would encounter interstellar hydrogen in such compressed form that its crew would be exposed to huge radiation doses, up to 10,000 sieverts in the first second. Because even a 10-centimeter layer of aluminum shielding would stop only a tiny fraction of this energy, the Edelsteins concluded that travel near lightspeed would be all but impossible.

Obousy, who handles the Project Icarus Web site, has his own credentials related to high speed travel, authoring a number of papers like the recent “Casimir energy and the possibility of higher dimensional manipulation” (abstract) that press for continued work into breakthrough propulsion. And when he talked to astrophysicist Ian O’Neill about warp drive concepts last week, Obousy said that we are in the process of laying down “…a mathematical and physical framework for how such a device might function, given the convenient caveat of a ‘sufficiently advanced technology.’” The device, he said, is purely theoretical as of now and we have no evidence that it could be built.

But should we keep investigating? On that score, Obousy has no doubts. With regard to shielding, he argues that metamaterials that bend radiation around objects are a place to begin, offering a conceivable barrier against the kind of radiation the Edelsteins are talking about. All of which makes for lively reading, as does Obousy’s continuing work on the Project Icarus team. Icarus is the descendant of Project Daedalus, the 1970′s era starship design created by the British Interplanetary Society. And while the Icarus guidelines focus on fusion as the propulsion method of choice, Obousy’s interests extend not just to warp drive but also to antimatter possibilities.

The latter is of interest because of its huge energy density, drawing on the abundant energy available within all matter. A single kilogram of matter contains 9×1016 J of energy. “[I]n simpler terms,” says Obousy, “about five tonnes of antimatter would theoretically be enough to fuel all the world’s energy consumption for a single year.” But as he notes in this entry on the Project Icarus site, storage is a huge problem. Positively charged positrons exert a Coulombic force of repulsion against each other, one of the reasons we can store only tiny amounts with current technology.

Ideal storage involves neutral antimatter — antimatter with no net charge — which points to antihydrogen (a stable atom containing a single positron and an antiproton) as a solution. Storing antihydrogen in the form of a Bose Einstein Condensate is one possibility for packing more of the stuff in less space.

As to the vast cost of antimatter production, Obousy has this to say:

With regards to the question of production, current methods utilized at CERN are prohibitively expensive and generation of antihydrogen in quantities that would be valuable to spaceflight would cost trillions of dollars. Despite this, it’s important to recognize that CERN is not a dedicated antimatter production facility and that antihydrogen production is a remarkable, yet tertiary goal of the facility. According to recent research, a low-energy antiproton source could be constructed in the USA at a cost of around $500M over a five year period, and would be an important first step for mass production of antimatter. However the overall roadmap for antimatter propulsion would involve timescales closer to 50 years.

If we start talking near-future uses of antimatter, though, tiny quantities could be put to work in projects like Steven Howe’s antimatter sail, which would use antihydrogen to initiate a fission reaction in a small, uranium-coated sail. Howe developed this idea for NASA’s now defunct Institute for Advanced Concepts. The antimatter, which drifts from storage unit to sail, causes fission as it encounters the uranium, producing neutrons and fission fragments that leave the sail at enormous speeds. NASA’s John Cole, who studied the antimatter sail idea while at Marshall Space Flight Center, told me in 2003 that the sail could develop specific power on the order of 2000 kilowatts per kilogram, enough to drastically shorten human missions to the outer planets even if Howe’s estimates are an order of magnitude off.

Or could antimatter be used as a trigger for fusion? Obousy is interested in the prospect:

Although a spacecraft propelled by antimatter may be many decades away, it maybe possible to use antimatter in the near future to catalyze nuclear fusion reactions using antimatter. Only very small quantities would be required and this might provide an alternative method for liberating energy from fusion. Because Icarus must use current, or near technology, it is possible that Icarus will utilize this form of propulsion…

And he adds:

Clearly a multitude of technological hurdles must be overcome before antimatter use becomes routine in space exploration. However, the fundamental theoretical issues have been proved. Antimatter exists, antihydrogen can be created technologically, antihydrogen can be stored. The rest is progress.

For more on the potential uses of antihydrogen in propulsion, see Nieto et al., “Controlled antihyrogen propulsion for NASA’s future in very deep space,” NASA/JPL Workshop on Physics for Planetary Exploration, 2004 (available online).

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{ 28 comments }

Zarpaulus February 22, 2010 at 11:39

Personally I think it will be much more cost effective to just use antimatter as a catalyst for fusion.

Eniac February 22, 2010 at 13:38

Since we are talking exotic propulsion, I think that the black hole idea is pretty neat. I am not versed enough in relativistic physics to be sure, but until I hear otherwise I remain convinced that a smallish black hole can be magnetized by even small external magnetic fields. The resulting magnetic fields near the event horizon will be extremely intense and keep the Hawking radiation from escaping, except as relativistic jets from the poles. This gives us the means of both grabbing the hole (by its magnetic field) and focusing its exhaust to use for propulsion. If only we could confine the jet(s) to mostly one of the poles. Perhaps this will happen automatically with an inhomogeneous external field? Otherwise, we’d have to think of ways of stopping or diverting one of the jets, which would be messy, to say the least.

The main advantage of black holes over antimatter would be storage: You could store any amount of fuel in an extremely small volume. After all, that is what black holes excel at. Plus, a black hole is not picky about its fuel, any type of matter will do. With any luck, the focusing effect of the intense internal magnetic field will be strong enough that a toroidal ship around the hole will have to worry only about radiation from external sources.

The biggest showstopper, of course, is the unavailability of small black holes. One wonders if there is a natural supply of them somewhere in the solar system, or if they could be manufactured, but neither of these scenarios seem realistic to me, at all.

David W February 22, 2010 at 15:44

The Fed generated trillions of dollars to bailout the financial system.
Why not generate trillions to make an anitmatter spacsehip that could creeate interstellar travel?
Who here doent think all of humanity would be better off spending trillions to create an interstellar civilization instead of proping up casino “investment” banks?

Ron S February 22, 2010 at 15:46

Searches for primordial black holes have null results. That leaves stellar collapse as the only known mechanism for black hole creation. Unfortunately, none of those are at hand and if they were we don’t know how to put them on a crash diet to reduce their mass. As they are, they are not useful for our purposes.

Once sometime can describe to me how to construct a sub-stellar mass black hole (without using magic wands and words of power), perhaps it will become meaningful to ask how one could give it charge and angular momentum.

Once we do (somehow) have our tame little BH, Hawking radiation is difficult to deal with since the particle spectrum is quite broad and much of that is neutral or photons. It may be better to give a more massive, and therefore low temperature, black hole some spin, with or without charge, and tap into that instead. At maximum spin, a BH can have up to 29% of its energy in its spin. That’s plenty, and likely allows for better and safer engineering solutions.

Of course this is all completely useless since there is no way to accomplish any of it. Planning propulsion systems around it is unproductive.

Enzo February 22, 2010 at 16:29

I remember a simple idea to store anti-hydrogen : make it solid and bombard it with electrons. Some of the positrons will annihilate, leaving it slightly electrically charged and being able to be electrically confined.

There’s also an interesting presentation at NIAC on positronium storage and propulsion :
http://www.niac.usra.edu/files/library/meetings/fellows/mar04/Edwards_Kenneth.pdf

Enzo February 22, 2010 at 16:31

I forgot to add a link to a company that works on positron storage :
http://www.pr-llc.com/

John Q February 22, 2010 at 18:48

The late, great Robert Forward had a newsletter devoted to the production, use, and storage of anti-matter (he referred to it whimsically as “anti-M” — this was about 20 years ago and I think the newsletter ran for two years). Unfortunately, I do not believe these writings were ever collected/re-printed into an accessible volume and it is possible his contributions have now been forgotten. I do recall his arguing forcefully that a directed, industrial effort at the creation of anti-matter, instead of just gathering it as a by-product of various research reactions, should bring about a substantial reduction in cost. The man had a lot of ideas that should be re-visited (he is always a good place to start when writing about future propulsion possibilities). I do not recall him ever writing about an “anti-matter” sail (or equivalent technology). That appears to be new but with Forward one should never count him out.

Administrator February 22, 2010 at 19:14

John, a collection of Forward’s antimatter newsletters is at the University of Alabama-Huntsville library, and I had the pleasure of going through it and other Forward papers some years back when working on my Centauri Dreams book. Forward never came up with Howe’s antimatter sail idea, but you’re certainly right about the magnitude of his contribution and the sheer fertility of his intellect! He’s been an inspiration to everyone in the field for years.

Wayne Farmer February 22, 2010 at 20:41

Regarding FTL travel: I imagine a civilization of slow-moving sentient fish dwelling in an abyssal zone, unaware of supercavitation technologies, and similarly unaware that only kilometers above them there existed a zone where their “space” abruptly transitioned into something called “air” — where their known limits on velocity no longer applied — and that beyond that something even more unimaginable called “vacuum” existed.

The universe and its physics are more wondrous than we can imagine. Keep on imagining!

David W February 22, 2010 at 21:03

Is there any way U of Alabama Hunsville could digitize them for their website ?(Forwards Papers)

Administrator February 22, 2010 at 21:21

David W, I suppose it’s possible that the UAH library could digitize these — would love to see it happen and I’ll send off an email suggesting same. Great idea!

JoeT. February 23, 2010 at 0:58

There’s a couple of possibilities, because the universe is fundamentally non linear. Build a closed system that rotates at near luminal velocity. (Accellerator) As it rotates, vary the parameters, referenced to some external point, eg delta v or delta m or delta r. The relativeistic mass on one side would be greater than the other. with +/- accelleration, “thrust” could be measured in tonnes!
Another, is to examine how energy is stored in “matter”. Time is not limited to 1/1. (Monotonic). A gradient in time around an imaginary point can function like a black hole, confining energy as if it was an infinate force with little or no losses. what can manipulate Time??? Think index of refraction, temperature, stress, medium etc. etc.

Enjoy

Steve Pease February 23, 2010 at 1:12

“Edelsteins concluded that travel near lightspeed would be all but impossible.”

This brings up two comments:
In 1947, a science committee, including a Nobelist, testified to Congress that, while bullets went faster than sound, it would be impossible for an airplane large enough to carry a man to exceed the sound barrier. At the date of the committee’s briefing, Chuck Yeager had already broken the soundbarrier – twice. Never say never.
But, I believe the comments about radiation from compressed interstellar hydrogen. So Don’t go there.

spaceman February 23, 2010 at 8:43

Is anyone here familiar with the two scifi novels The Killing Star and Flying to Valhalla by Charles Pelligrino? He makes matter-anti-matter annihilation powered rockets seem so plausible.

James M. Essig February 23, 2010 at 15:41

Hi Folks;

A really interesting notion would entail taking a very large blackhole and somehow causing the rate of zero point vacuuum field virtual particle production to be increased in one small spherical angle surface area section of the black hole. The rate of Hawking Radiation release at this location would dramatically increase for local surface area strong increases in virtual particle production.

Perhaps some process akin to the reverse process of the reduction in zero point EM virtual photon production inside the conductive plates of a Casimar Plate apparatus could be operable here.

If one wants to consider such a system on steriods whereby a billion solar mass black hole would be utilized for a 10 EXP 6 metric ton payload, the theoretical Isp can approach 1 C for highly directed thrust, assumming that the thrust stream exists in the form of light speed particles such as photons and/or gravity waves.

A one billion solar mass black hole based system would yield an M0/M1 value of about (10 EXP 27)(10 EXP 10)(10 EXP – 6) = 10 EXP 31. This would yield a gamma factor 0f 5 x 10 EXP 30!. In one year, the craft could travel 10 EXP 30 lightyears through space but the distance traveled from Earth will be many orders of magnitude greater yet due to universal space time expansion. The recessional velocity of the craft from Earth would then be many many orders greater than 10 EXP 30 C.

The chief caveats of: the continued expansion of the universe more or less at its current rate; the possibility of some form of body or region at the far end of the itenerary that we can call home; that we are not destroyed in a cosmic big rip or other catastrophic cosmic phase change; the ability to virtually entirely cloak the craft from otherwise ablissimating astrodynamic drag and extreme blue-shifted matter and energy wave species; and others.

Providing that at the very least, the above conditions can be met, we might have stupedously large real mattergy resources available to us.

If we can harness blackholes for propulsion, most likely, they will have a mass range on the order of one million to one trillion metric tons at first. Reducing the rate of virtual particle production in the vicinity of blackholes by some form of Casimar Plate analogue may enable blackholes with a mass of 10 EXP 3 to 10 EXP 6 metric tons to be safely used for propulsion.

Thus, if we can do a proper spin on the kinematical configurations of such conjectural systems, perhaps blackholes can be used as part of an excellent form of relativistic rockets with Isp ~ 1 C.

adam_grif February 23, 2010 at 19:29

I wish people would stop using the “well we broke the sound barrier, so -insert anything here- is no problem” non-argument.

Eniac February 23, 2010 at 19:33

James: I don’t think exotic physics are needed to restrict the Hawking radiation to certain angles. All that is needed is a magnetic moment. Because a dipole field of macroscopic size would be tremendously strong near its point of origin, the hole itself, any charged particles would get caught up in the field lines and focused on the poles. Just like those that are caught in the Earth’s much weaker field, only that these “northern lights” will take the form of extremely energetic relativistic jets. Even photons would probably interact with such a strong, inhomogeneous field, and generate particle/antiparticle that are then likewise focused.

At least that is my wishful thinking, not backed up even by back-of-the-envelope calculations, but plausible sounding, to me. Perhaps someone with better grounding in general relativity can shed some light. We do know such jets can exist on a larger scale, because we see them coming out of AGNs.

I am not sure, but I think the magnetic moment of a small black hole decays quickly, so we would not find them with a preformed magnetic moment. However, if it decays it should also be inducible, so by applying an external field we ought to be able to generate and control the focusing effect. Because the hole is so small, even a weak macroscopic field should lead to relativistically strong fields near the event horizon after a magnetic moment is induced.

As the van Allen belts do around Earth, particles will bounce back and forth from pole to pole many times. If there was just a slight asymmetry between north and south poles, the jet on one side should be much stronger than that on the other (All particles approaching the maximum velocity along field lines will bounce from the stronger and hit the weaker pole). This is what would be used for propulsion. The flaw in this concept is that the source of such asymmetry is unclear. Maybe an inhomogeneous external field would suffice, but I can see no grounds whatsoever for that, except wishful hinking.

Of course I realize that all this is idle speculation without an actual black hole to try it on, but I don’t let that stop me.

Adam February 24, 2010 at 1:37

There are sonic analogues of black-holes available to desktop manipulation – in theory currently but in practice soon. Many of our current conjectures may soon be testable.

James M. Essig February 24, 2010 at 2:29

Hi Eniac;

Thanks for the clarification of your ideas. The concepts you proposed sound interesting. I hope they can be made to work.

The discussions at these last few threads have been great and I have learned much, from you Eniac as well as from the many others who have commented. I have some matters to address back here in the Washington DC metro area and so I will be away from posting at Tau Zero for about one week. But I must say, I like the blackhole magnetic dipole moment idea.

Regards;

Jim

george scaglione February 24, 2010 at 16:22

jim i will come back later to study more of these facinating concepts that you and others have posted but in so far as your idea of using a black hole to gain zpf propulsion i can only say GOOD going!! however i do not think we will be able to utilize this concept in reality before quite a long time has passed :( for now however i am very glad that nasa IS thinking in the direction of the utilization of new forms of propulsion to “just” get human crews around the solar system better! can not wait to hear more on any or all of these topics. i have noticed by the way that the tau zero topics of the last week or so have been fantastic indeed! as always my sincere respect to everyone your friend george

george scaglione February 24, 2010 at 16:30

one more thing crossed my mind as soon as i was about to sign off – it was that it had crossed my mind to use zpf propulsion to power spacecraft afew years ago when i first read about the energy produced by the zpf. lol i would not however be so dunb as to brag about that since i was probably the 4763rd person to “come up” with the idea! again respectfully your friend george

Greg February 24, 2010 at 21:59

@Eniac,
The positron jets that have been shown to originate from Black Hole poles seems to correspond to what your suggesting in reference to the magnetic moments separating the particle pairs.

george scaglione February 27, 2010 at 17:18

eniac,well i am astounded ! you know how many times that i have picked over this site by now!? and….! i have only just read your comment above about the storeing and possible manufacture of small black holes !!! holy mackeral ! if we could do things like that!… if we could …MANUFACTURE,things like that this whole discussion might just be a moot point! don’t get me wrong i mean that with all possible respect,but we don’t have but just may NEED exactly the kind of things you speak about! know what it all calls to mind? the advanced society from the book/movie 2001 !!! however my friend they where a “mere” few million years in advance of us. god it just occured to me that for that matter why not just use wormholes or the like? i may be pushing my luck and don’t get me wrong but wormholes are another idea i speak up for any time i get the chance. sincerely and respectfully your friend george

george scaglione February 28, 2010 at 13:07

eniac,well lol talk about worm holes advanced alien societies and the like ! it just so happens that last night my wife and i watched the film version of carl sagans “contact” sort of made all my points in one fell swoop!! gives you the idea that such societies can have been around for millions and excuse me,even,BILLIONS of years!!! best part? i CAN see how that could indeed be possible! again my friend,respectfully, george

george scaglione March 2, 2010 at 16:55

well with a whole new and probably exciting month of march in which to post and i just had to come back here for one more look.never being one to want to miss anything on any or all of these great topics.think i’ll swing over to the new march topice now. respectfully all your friend george

Martin Chroust-Masin July 23, 2010 at 23:24

David W. Said “The Fed generated trillions of dollars to bailout the financial system.
Why not generate trillions to make an anitmatter spacsehip that could creeate interstellar travel?
Who here doent think all of humanity would be better off spending trillions to create an interstellar civilization instead of proping up casino “investment” banks?”

If your economic system collapses, what are you going to do with that interstellar travel?

Martin J Sallberg November 2, 2010 at 5:38

Gravity have been shown to travel at the speed of light, yet black holes can affect their surroundings with their gravity. This means gravitons must be able to circumvent the curved spacetime. This is good evidence for the theory that gravity is the weakest force because gravitons are not confined to normal spacetime.Several scientific theories, including String Theory, predict that gravity and electromagnetism unify in higher dimensions. If an electromagnetic field could be made to leave normal spacetime, it would form a barrier that closes gravity into normal spacetime. Electromagnetism could be made to leave normal spacetime if it was absorbed by a vacuum energy deficiency. That vacuum energy deficiency could be created by the casimir effect. So a warp engine should consist of a supraconducting electromagnet and a series of casimir plates.

ljk November 19, 2010 at 0:26

Scientists capture antimatter atoms in particle breakthrough

UPDATED: 12:21 PM EST 11.18.10

(CNN) – Scientists have captured antimatter atoms for the first time, a breakthrough that could eventually help us to understand the nature and origins of the universe.

Researchers at CERN, the Geneva-based particle physics laboratory, have managed to confine single antihydrogen atoms in a magnetic trap.

This will allow them to conduct a more detailed study of antihydrogen, which will in turn allow scientists to compare matter and antimatter.

Understanding antimatter is one of the biggest challenges facing science — most theoretical physicists and cosmologists believe that at the Big Bang, when the universe was created, matter and antimatter were produced in equal amounts.

However, as our world is made up of matter, antimatter seems to have disappeared.

Understanding antimatter could shed light on why almost everything in the known universe consists of matter.

Antimatter has been very difficult to handle because matter and antimatter don’t get on, destroying each other instantly on contact in a violent flash of energy.

In a precursor to today’s experiment, in 2002 scientists at CERN produced antihydrogen atoms in large quantities, but they had an incredibly short lifespan — just several milliseconds — because the antihydrogen came into contact with the walls of their containers and the two annihilated each other.

In this latest experiment the lifespan of the antihydrogen atoms was extended by using magnetic fields to trap them and thus prevent them from coming into contact with matter.

The researchers created 38 antihydrogen atoms and held on to them for about a tenth of a second, which is long enough to study them says Professor Jeffrey Hangst, one of the team of CERN scientists who worked on the program.

Full article here:

http://mw.cnn.com/primary/_Ss9Dhy-igcgunG4ND

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