Looking to Lasers, Microwaves and Anti-Matter for Space Travel

As the 21st century unfolds, radically different forms of air and space vehicles will replace the clunky machines of today, whisking passengers at ultra-high speed around the Earth and outward into space.

Laboratories scattered around the world are delving into novel and exotic forms of propulsion. Breakthrough physics could well make possible ambitious human treks across interstellar distances.

Work is underway to harness antimatter as a way to shave travel time to the Moon down to minutes, or between Earth and Mars to a day. Meanwhile, laser and microwave technology is rapidly advancing the idea of beaming people and payloads effortlessly into Earth orbit, making fuel-guzzling rocketry look like the horse and buggy of yesteryear.

Nearly 100 years after the epoch-making exploits of the Wright Brothers -- the first successful sustained powered flights in a heavier-than-air machine -- visionary scientists and engineers see "far-reaching" ways to turn solar system touring into a Sunday drive.

Speedy, connect-the-dot travel -- leaving Earth for a distant point in space -- equates to a lot of groundbreaking work, quite literally. That translates into research dollars let loose to fund new avenues for space travel. Last year, a report to President Bush underscored that very issue.

The need to achieve breakthroughs in propulsion and space power was highlighted by the Commission on the Future of the United States Aerospace Industry, chaired by former Congressman Robert Walker. The blue-ribbon group reported to the President:

"The lengthy transit times that result from the use of currently available propulsion systems make human exploration of our solar system difficult, if not infeasible. While propulsion concepts, such as ion and plasma, and power sources, such as nuclear, offer the potential of cutting transit times for space exploration by half or more -- they are unable to significantly reduce the duration of deep-space missions," the report explained.

"New propulsion concepts based on breakthrough energy sources, such as antimatter energy systems, could result in a new propulsion paradigm that will revolutionize space transportation," the Commission study advised the President.

A bottom line of the Commission report: "In the nearer-term, nuclear fission and plasma sources should be actively pursued for space applications. In the longer-term, breakthrough energy sources that go beyond our current understanding of physical laws, such as nuclear fusion and antimatter, must be credibly investigated in order for us to practically pursue human exploration of the solar system and beyond. These energy sources should be the topic of a focused basic research effort."

If you're casting about for go/no go breakthrough propulsion ideas, you don't have to look too far. Try boundary-pushing study of Heaviside and Slepian forces, quantum vacuum energy, transient inertia, parametrized post-Newtonian gravity geometry, or deep Dirac energy theory.

Clearly, futuristic physics of flight doesn't come easy. But this form of mental gymnastics is home turf for Marc Millis of NASA's John Glenn Research Center in Cleveland, Ohio. Over the last several years, through 2002, he served as project manager for the Breakthrough Propulsion Physics (BPP) Project -- a subset of Revolutionary Propulsion Technology work spearheaded at NASA's Marshall Space Flight Center in Huntsville, Alabama.

The BPP effort spent a little over $1.5 million -- spread out over seven years -- to peer at and peer-review the visionary edge of knowledge. Funding for BPP and the Marshall work, however, was "deferred indefinitely" in 2003, although there's a glimmer of hope the research will be reinstated in the near future.

"My line in the sand is if the physics isn't understood completely, then it's in my camp," Millis told SPACE.com. "If the physics is understood, and it's a matter of technology," then it is in other camps."

Millis said the public is wondering when is NASA going to build Star Trek's Enterprise and warp drive where nobody else has gone before. His answer is short and sweet.

"This is not in the foreseeable future. Today it is still unknown if such visions are even achievable. But new possibilities continue to emerge from science," Millis points out. As for any "hot favorites" in what has been studied in the BPP undertaking to date, there aren't any. "Nor should there be…because that would be premature," he said.

The technical goals of the BPP project are straightforward, bracketed in terms of unearthing discoveries in mass, speed, and energy for space travel:

Discover new propulsion methods that eliminate or dramatically reduce the need for propellant. Discover how to circumvent existing limits to dramatically reduce transit times. Discover new energy methods to power these propulsion devices. These goals are the breakthroughs, Millis explained, that are needed to conquer the presently impossible ambition of human interstellar exploration. Moreover, what is space? That too is part of the BPP quest to seek a tangible reaction mass or energy source.

Manipulating spacetime itself, looking into warp drives and wormholes - all in a day's work for those on the trail of breakthrough propulsion physics. What is of utmost importance, Millis quickly added, is to conduct visionary research in a credible manner.

There are pessimists of the day who assume all of this is now and will be forever impossible, Millis said. "We stand far more to gain by making the attempt than by giving up."

There are clues to breakthrough physics out there in the Universe at large, Millis said. For example, recent astronomical observations and discussion centers on such items as accelerated expansion and the lingering dark matter problem.

The Universe is a caldron of forces that offer insight into forms of propulsion considered exotic today. "In looking at it from a different perspective, we might see something that others would overlook," Millis said, be it the whole area of faster-than-light or delving into quantum non-locality entanglement.

"These are things that physicists are observing," Millis said. So we're just asking the question: Is this going to be useful for propulsion or not?"

"We are at the pinnacle of our knowledge…but we always were. That's the funny thing about pinnacles. They are a momentary illusion that you've got everything you know. You are basing that on what you know rather than what you haven't yet discovered," Millis said.

Anybody looking outward over the next 100 years to venture a guess as to what space travel breakthroughs will occur deserves hazard pay.

"But we must keep pushing that envelope…to keep trying to make the impossible possible. If we keep doing that, the future will be interesting. If we don't, I think the consequences would be fatal," Millis concluded.

The goal of Hbar Technologies, LLC of Chicago, Illinois is "making antimatter matter".

The research group is actively studying an antimatter-driven sail for deep space. They are blueprinting a system that could allow probes to be sent to the Kuiper belt and beyond, made possible by funds from the NASA Institute for Advanced Concepts (NIAC).

Many think that antimatter is more "mysterium" than real. In fact, antimatter is already being generated at facilities such as Brookhaven National Laboratory in New York and Fermi National Accelerator Laboratory in Illinois.

These labs produce antimatter by accelerating particles, such as protons, near the speed of light and ramming them into targets. The current worldwide, annual production of antimatter is only two billionths of a gram. Dramatic improvements in the production, storage and use of antimatter will be required to make it a viable propulsion alternative.

Although currently produced and stockpiled in small quantities using Penning Traps, antimatter must be stored in much higher densities to be applicable for missions into the outer realms of our solar system.

"In order to solve many of the mysteries of the universe or to explore the solar system and beyond, one single technology must be developed -- high performance propulsion, said Steven Howe, co-founder and CEO of Hbar. "In essence, future missions to deep space will require specific impulses of over 50,000 seconds in order to accomplish the mission within the career lifetime of an individual, 40 years," he said.

Only two technologies available to humankind offer such performance: fusion and antimatter. Fusion has proven unattainable despite forty years of research and billions of dollars. Antimatter, alternatively, Howe said, reacts 100 percent of the time in a well-described manner. Development of a suitable propulsion system, however, based on antimatter has yet to be shown.

"We propose to develop such a system," Howe explained. Along with Hbar Technologies co-founder and partner, Gerald Jackson, the firm is designing "a very straightforward system" that will produce a specific impulse of one million seconds. That system can be throttled, steered, and demonstrated within the next two years, the Hbar researchers report.

Currently, investigations are underway to develop high-capacity storage of antimatter in the form of antihydrogen. However, even if proven successful, no propulsion system has been demonstrated that would convert the antimatter into usable thrust.

The Hbar proposal is to utilize antiproton-induced fission to directly propel a small sail. By illuminating a thin foil of uranium with a stream of antiprotons, a million second propulsion system will be created - with no high temperatures, no magnetic fields, and no massive power supplies.

The researchers envision a lightweight sail that holds a trap of antimatter using a series of lightweight cables. For deep space missions to the Kuiper Belt, early results indicate that only 30 milligrams of antimatter are needed. For a mission to Alpha Centauri, a few tens of grams are required. The antimatter will be in the form of antihydrogen and will be stored as nano-flakes or as distributed atoms. However, high capacity storage of antihydrogen is work in progress, although that capability appears reasonable to expect in the near future, Howe said.

The sail-mounted trap need only have the ability to release pulses of particles at intervals. The cloud of particles will escape the trap and expand into the vacuum. Striking the uranium-coated sail will cause fissions. The captured fission products will propel the sail forward.

"By pursing this path of research, we hope to develop the one technology that will allow humanity to reach farther than ever before and see what lies beyond," Howe said.

Over the last two years, a major gathering of worldwide experts in microwave and laser power beaming has been held -- in the United States in 2002 and this year in Japan. A third confab is to take place in Troy, New York in 2004.

The international symposiums on beamed energy propulsion have shown that steady progress is being made, said Andrew Pakhomov, Associate Professor of Physics at the University of Alabama in Huntsville.

"These are serious scientific meetings," Pakhomov said. Along with the experts from the United States and Japan, scientists and engineers from Russia, Germany, France, Canada, Brazil, Korea and India attend the meetings to share results in power beaming research, he said.

Laser power beaming work is in the lead, with more money being applied to that technology, Pakhomov commented. "Maybe in two or three years, I hope we see a serious breakthrough."

Pakhomov saluted a recent experiment that highlights the increasing intensity of work.

Power beaming has moved a step closer to becoming workable thanks to researchers at NASA's Marshall Space Flight Center in Huntsville, Alabama, Dryden Flight Research Center at Edwards, California, along with experts at the University of Alabama in Huntsville.

The team has repeatedly flown a small-scale aircraft that flies solely by means of propulsive power transmitted via ground-based laser. The laser tracks the aircraft in flight, directing its energy beam at specially designed photovoltaic cells carried onboard to power the plane's propeller.

"We're clearly at a threshold," said Leik Myrabo of Bennington, Vermont. He is the just elected President of the newly formed International Society for Beamed Energy Propulsion (ISBEP).

Myrabo is no newcomer to power beaming. On October 2, 2000, after years of study, trial and error, his Lightcraft design rode a powerful shaft of laser light to a world altitude record at the Army's White Sands, New Mexico test site.

That breakthrough experiment utilized a ground-based laser to pulse a cavity of air on the Lightcraft to the point that it repeatedly exploded, propelling the spacecraft forward. In the future, highly energetic fuels could be super-heated in a similar way. A network of power beaming stations on the ground, as well as in Earth orbit, could support skyway and spaceway traffic lanes.

"Power beaming is definitely a worldwide phenomenon. Nobody is getting rich on the research…but the foundations are being set right now for what I think will become a revolution," Myrabo told SPACE.com. "It's going to change everything. It will change the way we get around the planet and venturing off our world," he said.

Myrabo envisions vehicles of the future dropping by your local neighborhood to pick you up, rather than having to fight traffic en route to any air or spaceport. Individuals can be "tractor beamed" through the sky in these craft, transported anywhere in the world in 45 minutes...or directly into space in a few minutes time.

"I see the Earth-Moon system as being colonized. Beamed energy propulsion will be the way of getting to orbit, to-and-from high orbit, and to-and-from the Moon. Much will change," Myrabo believes. The Moon seems to be a logical place to build communities. Terra firma already exists on the Moon, he added, rather than waiting for the construction of gigantic colonies. Those too will come in time.

An early objective of ISBEP is to capitalize on big lasers and microwave devices that are already in service around the world. "We want to set these up as user facilities. Researchers can use these facilities, get their data…all for a reasonable price. This way you avoid the big expenditures that created so many false starts in the past," Myrabo said.

Like the laser beam aircraft tests done at Marshall Space Flight Center, more experiments are needed, Myrabo explained. One idea is use of a platform-mounted laser in orbit, modest in power, to accelerate a vehicle through space "just to make a point that it can be done."

Lab work on the Lightcraft idea and other vehicle concepts is ongoing, Myrabo said. "The Wright Brothers had an edge over everybody else because they could control their machines…and that's needed now to go to ever-higher altitudes with power beaming."

We have so much in our hands right now, as far as technology, to create a power beam-based revolution, Myrabo said.

"There's a lot of physics today we are not applying to our propulsion and power systems. Many engineers are pre-occupied with chemical fuels. We really are talking about energetics. Imagine turning up the energetics a factor of ten or a hundred. That could radically transform what engines we use with that propellant…and what vehicles those engines can propel."

"The physics of flight will change. Right now we've got vehicles that by future standards are under-powered. The future ones…you're going to blink and they are gone," Myrabo predicted.

"If any of these schemes were feasible, they would have been reduced to practice by intelligent aliens thousands or millions of years ago. We do not observe their traffic. Hence either there are no intelligent E.T.'s or none of these schemes are feasible."

Question for you regarding the first sentence: why would we not be the first in this area to reach this point in technology? The second sentence also raises some questions: if the traffic existed, would we be able to observe it? Would such traffic want to be observed? I would imagine a race that possesed that advanced of a technology would also be able to avoid our relatively simple methods of detection. Then there are the problems of applying human logic and questions to a system that includes non-human entities.

"Question for you regarding the first sentence: why would we not be the first in this area to reach this point in technology?"

As Sagan repeatedly told us, we are the lowest, most recent, Johnny-come-lately "intelligent" species. The Sun is a 3rd generation star. There has been ample time for the rise of civilizations far more advanced than ours. Imagine our technology in 10,000--or 100,000 years (if we survive). Thus pretty much everyone "else"--if there is anyone--has technology far, far beyond ours.

" The second sentence also raises some questions: if the traffic existed, would we be able to observe it?"

Eventually one would land on the lawn of the White House. We would see (e.g.) Cherenkov radiation or other "signs" of their passage.

"Would such traffic want to be observed?"

A single race or "Galactic Federation" might have reasons for not being observed: the old "we are in a game preserve" argument. But if intelligence is common and widespread, eventually there will be one or a hundred civilizations that give the finger (or tentacle) to the "rules" and makes contact anyway.

--Boris

A single race or "Galactic Federation" might have reasons for not being observed: the old "we are in a game preserve" argument. But if intelligence is common and widespread, eventually there will be one or a hundred civilizations that give the finger (or tentacle) to the "rules" and makes contact anyway.

Unless SR and GR truly limit travel to below c (which to date looks like the case), meaning all of the exotic technology in the universe would still leave you "stuck" within your solar system (unless you devise a generation ship or use the Lorenz Transformation to "get there"). Either one is pretty much a one-way journey. So we may find that solar system exploration (other than EM and gravity observations) is the only viable option.

So there may be hundreds or even thousands or intelligent species, however, there would not be an interstellar civilization/galactic federation.

If you use a map from your home world, it will seem as if you're going much faster than c. If you use a relativity map, you still get the benefit of time dilation. A 1g acceleration will get you going pretty fast if it can be sustained over a period of months or years.

"So there may be hundreds or even thousands or intelligent species, however, there would not be an interstellar civilization/galactic federation."

Remember the old von-Neumann argument: even at 5% of "C" there has been plenty of time to visit every star in the galaxy. The high pay-off is to build self-replicating probes which construct copies of themselves at the destination, download their memories, and then each takes off at 0.05c for another random star. Eventually a scion staggers home by random walk and dumps the collected data of all its ancestors. Huge pay-off for a small initial investment. If we can think of this, super-intelligent ETs would also--and there's be a traffic jam at (e.g.) Sol.

No reason for a probe not to announce itself once it finds intelligence; quite the contrary. There is very little down- side for the sending civilization.

Plus, who says ETs have to have lifetimes limited to a few decades...?

--Boris

"If you use a map from your home world, it will seem as if you're going much faster than c."

???!!??
A MAP?!?!

"If you use a relativity map, you still get the benefit of time dilation. A 1g acceleration will get you going pretty fast if it can be sustained over a period of months or years."

1 g = 1.032 ly/(year)². However, neglecting Einstein, each kilogram travelling at 0.99999c will have 4.89x10¹⁷ joules of kinetic energy. Since a year is roughly (pi)x10⁷ seconds, this works out to roughy 1.5 megawatt-years per kilogram. Call it two for various losses.

If you are carrying your propulsion with you, it must weigh much less than a kilogram and have a similarly small volume. The engineering problem (ignoring relativity!) is to stuff two 1,000-MW nuclear power plant into (say) 100 grams and a few cubic centimeters. Scale up until you hit 'enterprise'.

--Boris

We have been down this road before. :-). I don't see a race squandering the precious resources of its own solar system with no practical benefit. Remember a self-replicating probe would "evolve" like any other "life form". I think a races time, effort, and cost would be better spent on more complex observatories than random space probes. The other rub, is how do these probes replicate? Where is the energy to not only do this but to get back out of the gravity well of either the star or object it used to make the replication?

I just don’t buy it. :-)

Plus, who says ETs have to have lifetimes limited to a few decades...?

I wonder. Remember out Sun is either a second or third generation star. If the life spans of an organism were much longer than ours, would evolution be slowed enough to preclude intelligent life?

The problem is that a continuous one g acceleration will still not allow you to exceed the speed of light (c).

Wild speculation warning:
If we could ever develop something analogous to Star Trek's "beam me up" technology, so we could convert people to an EM signal and transmit them somewhere at lightspeed, then the transit time for the travelers would seem instantaneous. All we'd need is a reception station at the other end (something Star Trek somehow seems to avoid).

To create a network of reception stations, we'd need to send ships the slow way, perhaps they'd be robotic, and have them assemble receivers at desired (or even random) locations. That's the first phase, and it would take a few million years to get this infrastructure built over a good chunk of the galaxy.

But when it's finally built -- actually while it's being built, as far as it extends -- we could be traveling around as EM signals. Such transmissions might not look all that different from natural light, so they'd be undetectable, unless we were looking for them.

"We have been down this road before. :-). I don't see a race squandering the precious resources of its own solar system with no practical benefit. Remember a self-replicating probe would "evolve" like any other "life form". I think a races time, effort, and cost would be better spent on more complex observatories than random space probes. The other rub, is how do these probes replicate? Where is the energy to not only do this but to get back out of the gravity well of either the star or object it used to make the replication?"

Indeed we have. Firstly, a civilization with 10,000 or 100,000 years of technology would not regard such a probe as a big investment. Secondly, they replicate using 'local' resources as possible. Some destinations will not permit replication; that is why it is wise to send ~100 probes rather than one or two. You expect attrition. (You also expect geometric explosion in the numbers that DO make it)...These are self-replicating robots, and there is little reason to expect 'evolution' unless built in. They have firmware or hardware programs on how to build an offspring and probably have nanotechnology to "make it so". As to the energy question, that is the least of their worries. Probes are not in a hurry. They can gather He3 or use solar sails, or other technologies we cannot foresee. Reaching 0.05c might even be possible by patiently exploiting repeated slingshots in the current system.

--Boris

Plus, who says ETs have to have lifetimes limited to a few decades...?

"I wonder. Remember our Sun is either a second or third generation star. If the life spans of an organism were much longer than ours, would evolution be slowed enough to preclude intelligent life?"

I certainly agree about longer lifetime vs. mutation rate.

But for most of the Earth's 4.5 billion years only single-celled life has existed. For almost 3 billion of those years life was in a primitive condition.

Had the Cambrian 'explosion' (a profusion of life) occurred a half-billion years earlier (for reasons we cannot know), we would probably see more advanced life (and technology) here now.

There would be, then, the possibility of advanced technology from another 2nd or 3rd generation star elsewhere.

"If we could ever develop something analogous to Star Trek's "beam me up" technology, so we could convert people to an EM signal and transmit them somewhere at lightspeed, then the transit time for the travelers would seem instantaneous. All we'd need is a reception station at the other end (something Star Trek somehow seems to avoid)."

Aargh.

There are two ways to do this: (1) "record" the position and state of every atom in the transportee and send the information. At the other end (how did you get there?) you have a big tank of atoms and build them up into an exact copy of the guy back home. Now you have two guys, both with the same SSN and bank account, same DNA, same fingerprints...so you murder the original. Hmm.

(2) You convert the victim into energy and send him that way. That's gonna hurt. Also there is a distinct danger of blowing up the Earth because a 100-kg person bears (E=mc2) 9x10¹⁸ joules of energy. A big catcher's mitt to catch that beam...

But even worse, once you catch it, you have to DEAL with it; convert it (somehow) back into mass. Presumably the instructions for making the person ride the BEAM on a subcarrier or something. Catchers' mitt better be big and good, otherwise you will vaporize the target planet.

And both schemes leave you (the transportee) at the mercy of the inverse-square law...you're melting, melting (like the Wicked Witch of the West) with distance, pretty soon the "BEAM" looks like a flashlight...then a firefly...then...poof! eaten by the redshift. Better take out some insurance either way!

--Boris

I'm not ready to design such a system, but there may be ways around the difficulties you mentioned. First, there's a great deal of redundancy in a human's structure. Other than the brain, the body's information could be greatly compressed. That might make the signal more managable. Re-conversion at the destination is indeed a problem. Probably a convenient herd of animals would be penned up near the station as a source of raw material. Something for PETA to worry about.

As for the fact that our intrepid travelers would be duplicated, that's probably true. I see no need to kill the one at the transmission station. There's not much chance of his ever encountering the far-away clone. There's another duplication problem caused when (and if) he sends himself to that same destination more than once. I'll let the moralists of the future deal with that one.

Remember a self-replicating probe would "evolve" like any other "life form".

If you haven't read it yet, check out the sci-fi novel "Code of the Lifemaker", by James P. Hogan. It's out of print, but is pretty easy to find in any used bookstore.

It examines that exact scenario, and does it very well. From one of his discussions about the book:

Then, one day, I was invited to attend a summer study that NASA was hosting at the Goddard Spaceflight Center, where various people from the agency, industry, and academia got together to discuss future space mission possibilities and the roles that computers would play in them. One concept we talked about was that of a self-replicating lunar factory, built from components fabricated out of lunar materials by an initial "seed" mission of advanced robots. The factory would build more robots, which in turn would construct more factories, and eventually the scheme would grow itself into a fully self-supporting operation capable of carrying out a vigorous export business to Earth. In fact, calculations showed that in twenty years the output could exceed the entire production of Earth's manufacturing history!
On the flight back to California, I at last made the connection that here was the way to get our electromechanical biosphere started. Imagine a scaled-up operation of that kind, developed by an advanced alien race, operating over interstellar distances to exploit the resources of distant planets. One of the missions goes seriously wrong, and the world of replicating machines that it spawns "mutates." Then, after a million years, say, have gone by . . .
I started writing CODE OF THE LIFEMAKER the day after I got back. A number of readers have written to say that the Prologue was worth the price of the book. The world that the messed-up alien mission ended up on was Titan, largest of the moons of Saturn, and the strange inhabitants who now dwell there are discovered in the course of exploration by humans.
The story also prompted lots of requests for a sequel. This appeared in 1995, entitled THE IMMORTALITY OPTION.

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