Reflections on the LightSail Project

by Paul Gilster on July 10, 2014

I was delighted to see Doug Stetson, the program manager for The Planetary Society’s LightSail effort, quoting Johannes Kepler in last night’s webcast. If you missed the Pasadena event, which took place at the KPCC Crawford Family Forum in Pasadena, CA, you can watch the recorded session here, and I highly recommend it. Kepler’s 1610 letter to Galileo added context to the excitement over LightSail, for solar sailing has a rich history. Kepler wrote of providing “ships or sails adapted to the heavenly breezes,” and added that “there will be some who will brave even that void.”

It’s an inspiring thought as we now look into the launch of a privately funded sail that can join IKAROS and NanoSail-D in a series of operational experiments that will hone our sail knowledge. The chief news of the Pasadena meeting was the announcement of an approximate launch date. LightSail-1 is scheduled to go into space aboard a SpaceX Falcon Heavy rocket in April of 2016. The quick video Mat Kaplan showed illustrating the Falcon Heavy in flight was likewise energizing: This is a booster made up of three Falcon 9 cores, meaning 27 rocket engines. The Planetary Society’s Jim Bell calls it a rocket that ‘opens up the outer Solar System.’

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Image: Artist’s concept of LightSail in space. Credit: Josh Spradling / The Planetary Society.

But let’s clear up that problem of sail nomenclature I referenced yesterday. What is being called LightSail-1 is the designation for two solar sail CubeSats, LightSail-A and LightSail-B. Whether LightSail-A or LightSail-B is the one to fly next depends upon systems tests that will be completed in coming months, as Jason Davis explains in LightSail Update: Launch Dates:

If LightSail-A goes to space, it won’t reach a high enough altitude for the momentum it gains from solar sailing to overcome atmospheric drag. The spacecraft will deploy its sails, capture images, and communicate with the ground, giving engineers a chance to work through any problems en route to a full-fledged solar sailing flight.

LightSail-B, on the other hand, will embark upon true solar sailing, using the momentum of solar photons to increase its velocity. Usefully, both missions now seem likely to fly. Stetson told the Pasadena audience that an opportunity exists for launching LightSail-A to a lower orbit, a test flight that would occur in May of 2015. Joining the crowd by Skype, he went on to say that a test like this would validate the sail by putting it through a full deployment in lower Earth orbit.

The image below, shown by Stetson during the presentation, shows LightSail-B capturing forward momentum from solar photons. You can see the changes in attitude as the sail, orbiting the Earth, adjusts its position to maximize the effect of sunlight. Ultimately, turning the sail at key points in the orbit allows the orbit to be raised, allowing the prospect of escaping Earth’s orbit entirely. We can envision a day when CubeSats, those tiny marvels of inexpensive engineering, could be equipped with sails and sent out in swarms to explore the Solar System.

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Image: In order to capture forward momentum from the sun’s rays, LightSail-1 will make two 90 degree pitches during an orbit. Credit: LightSail Team / The Planetary Society.

Planetary Society CEO Bill Nye refers to solar sailing in terms of power, utilizing ‘a fusion reactor at a safe distance, the Sun.’ Assuming we get LightSail-B into space in the spring of 2016, the surrounding package will be quite interesting. LightSail will launch embedded within a satellite called Prox-1. The latter, developed at Georgia Tech, was designed to conduct autonomous proximity operations in which two spacecraft operate at close quarters. Prox-1 will release the sail and then rendezvous with it, closing to within fifty meters and capturing images of LightSail. The actual sail deployment will occur after several weeks of operations.

We’re going to get some remarkable video of sail deployment, both from the cameras aboard the LightSail craft as well as those aboard Prox-1. System engineer Barbara Plante (Boreal Space/Ecliptic Enterprises) went on to discuss spacecraft attitude control after showing the crowd a large piece of the 4.5 micron sail material, roughly 1/50th the width of a human hair. Sail packaging and deployment is complicated business, but Plante said she was struck by the elegance of the design, referring to solar sailing as a ‘green method’ for exploration.

Looking to the future, David Brin joined the group by Skype as the panel discussed the implications of today’s sail experiments. Solar sails run into the obvious problem of diminishing sunlight the farther one goes from our star. The way around that problem is to imagine a future space infrastructure for power generation, one in which power is readily available for large laser arrays that can illuminate a sail and push it entirely out of the Solar System. Brin suggested the Sun’s gravitational lens at 550 AU and beyond as a natural target for later generation sails, a way of exploiting the extreme magnifications this natural lensing provides for our instruments.

For me, the word ‘lightsail’ has always referred to a sail under this kind of beamed power, and now I’ll have to be careful not to confuse that kind of sail with the experiments LightSail-1 will offer in nearby space. But we always need to think about how today’s efforts play into a larger scenario, including so-called ‘Sundiver’ missions that unfurl their sails after a close pass by the Sun to achieve high accelerations. It seems fitting to end this piece on LightSail-1 with Louis Friedman’s thoughts on such missions, he being a key player in making this happen.

Friedman, as we’ve seen, worked at the Jet Propulsion Laboratory on the design of a large sail targeting Comet Halley, and although that mission never flew, he has been an advocate of sail designs for decades, anticipating that we would one day understand the virtues of leaving propellant behind and shedding the rocket equation altogether. In his 1988 book Starsailing: Solar Sails and Interstellar Travel, he brings his experience to the long view:

[The sail] would provide a nearly perfect means of interstellar travel — except that it requires sunlight, and we will run out of that as we leave the solar system, a circumstance that could leave us becalmed, like a terrestrial sailboat on a windless ocean. We could, however, use a series of gravity assist maneuvers to keep ourselves moving along. We could fly around Jupiter, for instance, then head in toward the sun, picking up a lot of speed with our sail. Then we could swing around and head out past Jupiter and Saturn, picking up even more speed. With a large sail and with a close fly-by of the sun, assuming good thermal protection, we could conceivably exit the solar system at a rate of 40 astronomical units a year — in other words, we could travel through the whole solar system in about 1 year. Even at that great a speed, however, we would not reach the second star for 6,600 years! Not so good. Nevertheless, this use of gravity assist and solar sailing combined offers real promise for the use of solar sails even for traveling to the outer planets, which may extend the range of the interplanetary shuttle.

But Friedman has interstellar thinking in his bones. Intimately familiar with the work of Robert Forward, he goes on to describe the latter’s concept of a 3.6 kilometer sail that would, using laser beaming technologies, get a one-ton payload to Alpha Centauri in about 40 years, reaching a bit more than one-tenth of lightspeed. It was one of many Forward designs that speculate on what a human presence in space and the immense power of directed light could accomplish.

After the years at JPL, working with Bruce Murray and Carl Sagan, the time on Voyager, the 32 years as executive director of The Planetary Society, Louis Friedman, one of its founders, is seeing yet another result of his efforts pay off. I can assure you that when LightSail-1 flies, we’ll pop open a bottle of Champagne at my house, and the first toast of the evening will go to him.

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{ 31 comments… read them below or add one }

ljk July 10, 2014 at 11:17

Quoting from the main article:

“System engineer Barbara Plante (Boreal Space/Ecliptic Enterprises) went on to discuss spacecraft attitude control after showing the crowd a large piece of the 4.5 micron sail material, roughly 1/50th the width of a human hair. Sail packaging and deployment is complicated business, but Plante said she was struck by the elegance of the design, referring to solar sailing as a ‘green method’ for exploration.”

I am all for protecting the environment, but this calling solar sailing “green” strikes me as an attempt to be both trendy and PC. Yes it is an elegant and relatively clean design (if you ignore the fact that resources and energy will be required to build such craft in the first place), but solar sails will be traveling through a medium that is chock full of deadly radiation, extremes of temperature, and naturally occurring debris that will not hesitate to tear such a vessel to shreds should it get up to real speeds. The “green” comment was clearly a placebo for the general public.

Bussard ramjets were also a relatively elegant design, until we found out they made better brakes. Plus they required fusion propulsion, which is still probably decades away just for the versions that might bring us power on the ground.

Orion of course is the dirty Cold War creation that will continue to be avoided by the Western spacefaring nations for more political and PC reasons than physics and logic. I suspect China and Russia have long realized this will be their ticket into creating a permanent presence in the Sol system and then a relatively quicker way to the nearer stars.

And then this quote:

“Looking to the future, David Brin joined the group by Skype as the panel discussed the implications of today’s sail experiments. Solar sails run into the obvious problem of diminishing sunlight the farther one goes from our star. The way around that problem is to imagine a future space infrastructure for power generation, one in which power is readily available for large laser arrays that can illuminate a sail and push it entirely out of the Solar System. Brin suggested the Sun’s gravitational lens at 550 AU and beyond as a natural target for later generation sails, a way of exploiting the extreme magnifications this natural lensing provides for our instruments.”

That is the other issue with light sails – and yes I mean light sails, the kind that need a bit of artificial help to get from here to Alpha Centauri. Unlike say Orion, beamed sails will not only need a pretty big infrastructure setup in space, but powerful laser beams to push them to the speeds mentioned in the quote above.

Not only does this mean waiting more decades and centuries before we could get a fast probe to Alpha Centauri if we go via this method – not to mention counting on human civilization to permanently colonize space in the first place (hasn’t really happened since we started launching satellites way back in 1957) – but it also requires an instrument that I think would make those who worry about the destructive potential of human technological creations give major pause to.

A powerful laser or series of lasers sitting on platforms in space, capable of causing major destruction just as much as their ability to push an elegant vessel to the stars. Who will build and operate such devices? Will it be a consortium of nations or a corporation, depending on who finally colonizes space? What if other nations decide they need their own space laser battle stations – I mean instrument platforms for peaceful exploration – to create a balance with other powers?

Yes I know just about anything humans make can be used for good or evil, but powerful lasers have one distinct advantage over say something powered by nuclear bomb detonations – and by advantage I mean in terms of a superior weapon: They can move at the speed of light, which means just about any target in the inner Sol system can be struck ranging from seconds to minutes. At least a nuclear missile will take time, perhaps enough to be avoided or destroyed.

I hope I am wrong of course. I hope by the time we have industrial colonies in space we will be better behaved at least up in the Final Frontier. I hope any laser platforms will be securely run by peaceful organizations dedicated to the scientific exploration of the galaxy. I hope our first starships are literal works of art and aesthetically pleasing vanguards of humanity sailing quite literally into the wider Milky Way.

But just to summarize my two big concerns, because unless humans undergo a radical change in the next few centuries they will remain essentially as they have been for millions of years: An infrastructure setup in the Sol system that will take decades or more to establish (remember how the original Daedalus team wanted to mine helium-3 from Jupiter’s atmosphere – oy) and a method of propulsion that can be converted into an extremely effective and deadly weapon in the wrong hands.

For all that we might as well get back to making Orion a reality. It has the advantages of a propulsion system we have possessed since 1945 and it could be built and launched rather soon without needing a space colony construction infrastructure. And once again, there are at least two spacefaring nuclear nations I know of that will not be nearly as squeamish about using Orion if they wanted to.

Sails are romantic and beautiful, I know. And I would prefer a “nice” way to strutting our stuff into the Cosmos. However, we don’t know how society may turn in the near future. We keep hoping and waiting for a posterity we assume will have our interests and goals in mind. If we want to see Alpha Centauri up close in the relatively near future, do we want to bank on that same future being what we want?

Maybe those who grew up during Apollo being promised all sorts of things just to watch the various space agencies drop the ball for reasons that had nothing to do with logic can understand my feelings and concerns.

ljk July 10, 2014 at 11:44

To add: Unless we become amazingly altruistic and rich in the future, no nation or corporation is going to build a huge space laser just to push a light sail to Alpha Centauri for science.

We will have to hope that if such a platform is created – and what use would a government or corporation have for a space laser system – the ones in control of such an instrument will let the scientists bleed off some time and beaming power to get a sail to the next star system.

I know one thing: Even if those powers do agree to let a few scientists launch a star probe, it won’t come cheap and that could halt things right there.

This is why I am so hesitant when I hear about a method of interstellar travel that requires a human civilization which has expanded into space and is ready and willing to use its resources and funds on flying to the stars for science.

Apollo only happened because the USA and USSR were in geopolitical contest with each other. Look what happened the moment the United States “won” that battle. Scientists had to go along for the literal ride if they ever want to study lunar rocks and regolith up close, which they are still doing over four decades later because there has not been a sample of lunar surface brought to Earth since 1976.

Louis Friedman July 10, 2014 at 12:47

Still working on it Paul. I am co-leading a study on missions to explore the interstellar medium with very fast solar sail trajectories at the Keck Institute for Space Studies (see website). Also have a book now with a publisher looking at the future of human spaceflight: From Mars to the Stars.

Paul Gilster July 10, 2014 at 13:06

Good! I was planning to ask you at some point about plans for a new book. Wonderful to hear that it’s in the works. Keep us posted.

Alex Tolley July 10, 2014 at 13:47

To me, lightsail-1 epitomizes the trend in space exploration. Within a decade, we have a solar sail 1/20 the area of the earlier Cosmos-1 (32 m^2 vs 600 m^2), yet as capable as the instrumentation and sensors reduce in size. Cubesats are both a triumph of size and the advantages of standardization and low costs. As a result, we will see the advantages of “fast and cheap” as these probes carry out all sorts of low cost sensing to complement the big, customized robots. This is Rodney Brooks idea coming to fruition. The smaller size of the sail allows for the use of booms made of 2 curved metal tapes that can be rolled up yet extend to form a stiff boom meters in length.

For interstellar probes, unlike the huge size and cost of big probes (like nuclear bomb propelled Orion), small, possibly Starwisp sized probes can be sent out in large numbers to the stars. Many will fail, but the large numbers will ensure enough survive to meet their mission goals. In many respects, I think David Brin has it right in his novel Existence, small vessels are the way to go, not huge lumbering star ships so fondly imagined in SF movies (e.g. Independence Day).

Alex Tolley July 10, 2014 at 14:00

@ljk – As Rob Henry intimated in an earlier thread, a location for the energy source should be much closer to the sun (e.g. 0.1 AU). Which makes targeting Earth environs much harder. It is also a big target, so that countermeasures are relatively easy. I would worry much less about such a beam power source than about stray nuclear bombs from an Orion class ship.

However the main issue is economics. The economics of boosting numbers of diminutive sails to high velocities is likely to be far lower than even launching an Orion. Which means that sails (or small robots in general) will likely happen far earlier in our future. I would expect this lower cost to increase our likelihood of reaching the stars.

Alex Tolley July 10, 2014 at 14:13

What I would like to see is some speculative discussion of hybrid vehicles using sail material. Solar/Light sails are generally assumed to be purely reflectors of photons for propulsion. But as we have seen with O’Neill colonies, that reflection also can be used as a concentrator (colonies light days out in the deep solar system). Could sails be shape changing to focus light as well for other propulsion, e,g, generating the electricity for electric engines (e.g. http://web.mit.edu/aeroastro/labs/spl/research_ieps.htm?

Could sails be the way to focus sunlight on other worlds to make then more habitable? For example, could many small sails provide the extra light to warm and illuminate parts of Mars, providing the realistic approach to the solettas in KSR’s Mars trilogy?

What technologies need to be developed to make sails adaptable to a wider range of modes than just e-m reflection?

Michael July 10, 2014 at 14:42

Is there something wrong with the orbit? I mean shouldn’t the reflected beam hit the Earth as much as possible to gain maximum thrust (force vector spends more time away from the earth increasing the orbit)

ljk July 10, 2014 at 17:25

Alex Tolley said on July 10, 2014 at 14:00:

“@ljk – As Rob Henry intimated in an earlier thread, a location for the energy source should be much closer to the sun (e.g. 0.1 AU). Which makes targeting Earth environs much harder. It is also a big target, so that countermeasures are relatively easy. I would worry much less about such a beam power source than about stray nuclear bombs from an Orion class ship.”

Since having a space laser platform implies permanent human settlements in the Sol system, I was not just thinking about the laser being used against targets on Earth but other inner system settled worlds, stations, ships, probes, and any other space infrastructure one might want to attack.

You bring up another point about the platform being a large target: This would mean it is vulnerable to attack in turn whether it is a threat or not.

So would this mean the platform needs its own defense mechanisms? So be it, unless those running it or if it gets taken over turn out to be not so nice.

Hopefully I am just overcompensating for potential human frailties such as aggression, stupidity, and ignorance. My one hope is that the harshness of space will weed out much of those traits and leave those who remain smart enough to know cooperation is the only path to success beyond Earth.

Then you said:

“However the main issue is economics. The economics of boosting numbers of diminutive sails to high velocities is likely to be far lower than even launching an Orion. Which means that sails (or small robots in general) will likely happen far earlier in our future. I would expect this lower cost to increase our likelihood of reaching the stars.”

Hey if sails work then I am all for them. In fact I am for whatever methods get us to the stars so long as they are based on real physics and technology that won’t require some miracle or centuries to become possible.

Andrew Palfreyman July 10, 2014 at 18:23

What prevents us boosting the local solar power density by using mirrors, and perhaps lenses, close to the sun to produce almost-parallel beams that criss-cross our solar system to produce a rapid transport web? A hundredfold increase in Watts per square metre translates into a hundredfold increase in lightsail acceleration. A tenfold reduction in trip times is nothing to be sneezed at. Compared to solar-powered lasers, this seems relatively cheap and far less costly to maintain, and is also not nearly as weaponisable.

Alex Tolley July 10, 2014 at 20:53

@Michael – the only one that seems wrong to me is the position when the sail is on the shadowed side of Earth. I would expect it to be a mirror orientation to the sun side so that the thrust is still in the direction of the orbit.

There may be optimal orientations to maximize thrust in the direction of the orbit, although how much different from the simple diagram I am unsure without doing the calculations.

ljk July 11, 2014 at 9:30

Next question: What will keep an interstellar lightsail from being torn to shreds by debris it encounters along the way?

Will it be so big that it will take more than a few holes to make the sail ineffective as a method of propulsion? Would the equivalent of a Daedalus dust bug warden ahead of the sail do the trick? Could the laser also be utilized to take care of obstacles in the path of the probe?

Another question:

What will the laser and sail look like to someone on the receiving end of such a vessel from a distance? Should we be looking for similar signs in the heavens as part of our SETI efforts, assuming someone is coming our way?

Michael July 11, 2014 at 13:33

@Alex Tolley July 10, 2014 at 20:53

‘…the only one that seems wrong to me is the position when the sail is on the shadowed side of Earth. I would expect it to be a mirror orientation to the sun side so that the thrust is still in the direction of the orbit.’

I think our problem is the orbit is altered by the change in orientation of the sail because normally an elliptical orbit would start to form from the say sunlit side orientation. It may have been better pictured by an elliptical orbit first and then it would just be a repeat process to increase the orbit height. And I would think the dark side orientation should be the other way around than pictured so the thrust vector is in the direction of the orbit.

ljk July 11, 2014 at 14:03

Can they really? How about rockets and sails working in tandem rather than turn this into some kind of competition?

http://www.space.com/26488-solar-sails-could-beat-the-rocket-equation-animation.html

Is this kind of a selfie?

http://www.space.com/26490-solar-sail-mission-will-have-satellite-photographer-animation.html

Rob Henry July 11, 2014 at 20:54

Yes, I think you may have it that second time Michael. The higher the eccentricity the lower the minimum energy cost of further change. This makes these optimisations the sort of calculation best done through computer simulation, and the results of those can be counterintuitive.

Eniac July 11, 2014 at 21:21

Andrew Palfreyman:

What prevents us boosting the local solar power density by using mirrors

Optics. Sunlight is too diffuse to produce sharp, long range beams. At 1 AU, the sun covers about 1 degree in the sky, which means that any beam produced optically from its full light will diverge by at least 1 degree. You could reduce the divergence by blocking out some of the light (or going further away) but that would defeat the purpose by reducing intensity.

In different terms, if you wanted to double the amount of light shining on your sail from near the sun (as opposed to near the craft), you would need a mirror the size of the sun. If your mirror were near the craft, it would only have to be the size of the sail, but then it would be no better than just doubling the size of the sail to begin with.

Gregory Benford July 12, 2014 at 13:34

LJK:
GOOD comments. You can see how an industry using beamed power (mostly microwaves, which are actually easier and cheaper for many applications) to convey power and momentum to spacecraft at great distances, by consulting at

http://jamesbenford.com/papers-articles/sailships-beamed-propulsion/

Note these papers, easily downloaded:

“Space Propulsion and Power Beaming Using Millimeter Systems”, J. Benford and R. Dickinson, Intense Microwave Pulses III, H. Brandt, Ed.,SPIE 2557, 179 (1995). Also published in Space Energy and Transportation, 1, 211 (1996).

“Starship Sails Propelled by Cost-Optimized Directed Energy”, James Benford, JBIS 66, 85 (2013).

“Space Applications of High Power Microwaves”, James Benford, IEEE Trans. on Plasma Sci., 36, pg. 569, (2008).

Others on that page detail our extensive experiments and theory, showing that sails can be driven and stabilized by high power beams. My brother and I were the first to lift a sail in vacuum against gravity.

Yes, some beamed power systems can be used as weapons. Most technologies in space can be, where relative velocities are ~10 km/sec and beams do not scatter very much at all.

Rob Henry July 12, 2014 at 19:32

From how your describing it Eniac fixed mirrors sound useful for slowing payloads, or deflecting craft back into the inner solar system from round a large asteroid with tiny moons.

In the above case, mirrors can be made cheaply in extremely low gravity from moon-material, and the reason for it would be to give their particular main asteroid a trade advantage over others (even a small delta vee boost might shave a year or two off each round trip).

Eniac July 12, 2014 at 20:34

Gregory Benford:

Yes, some beamed power systems can be used as weapons. Most technologies in space can be, where relative velocities are ~10 km/sec and beams do not scatter very much at all.

Very true.

And I think what follows from that, like it or not, is that our eventual expansion into space will NOT be led by scientists, entrepreneurs, misfits, or religious fanatics, as people variously assume.

Rather, it will be led by Earth nation’s militaries. It will be a fast, avalanche-like self-reinforcing process, once the race begins, not the slow, methodical development most seem to envision.

Gregory Benford July 13, 2014 at 11:49

Eniac:
I think opening the solar system will resemble the opening American West.

Tains: transport. Settlers: mining, agriculture, herds. Moves to acquire territory: Louisiana Purchase, Mexican Wars. Rapid tech evolution.

Vast population increases, tho many robots. California census 1850: 73,000. Today: 38 million. We carry guns but the death rate is far lower than then. We’re rich beyond the comprehension of 1850.

swage July 14, 2014 at 9:55

“Yes, some beamed power systems can be used as weapons. Most technologies in space can be, where relative velocities are ~10 km/sec and beams do not scatter very much at all.”

That is right. Still… its not that there is a particular lack of planet annihilation potential. In fact the technology may become a safeguard against any and all ICBM based weaponry, in other words its EXACTLY that what certain nations want to build and they made heavy investments in that regard.

“Who will build and operate such devices? Will it be a consortium of nations or a corporation, depending on who finally colonizes space? What if other nations decide they need their own space laser battle stations – I mean instrument platforms for peaceful exploration – to create a balance with other powers?”

The answers to those questions are obvious, of course. Astonishingly obvious.

“Apollo only happened because the USA and USSR were in geopolitical contest with each other.”

“Unless we become amazingly altruistic and rich in the future, no nation or corporation is going to build a huge space laser just to push a light sail to Alpha Centauri for science. ”

Military spending globally totals around 1.2 trillion USD a year. We all know we need to accomplish something actually useful with that kind of funding. They are going to build weapons with it in any case. We have to make sure they build the right ones. And that isn’t actually not that difficult…

swage July 14, 2014 at 10:09

I believe a beam arms race is inevitable. Technically… its already underway. Its better than a nuclear arms race in my book. That’s why i believe this field will advance as rapidly in the future as it does today.

Yes, it has a bitter taste to it. But instead convincing brick-headed militarists about the necessity of funding space exploration we may as well disguise it as the “next logical advancement in global security and military dominance”, which is IS actually, but also so much more. What an amazing coincidence, really.

ljk July 14, 2014 at 15:43

The Final Frontier: It’s about a combination of obtaining the ultimate High Ground, grabbing all the resources, and making megatons of money in the process:

http://www.thefiscaltimes.com/Columns/2014/07/11/New-Space-Race-and-Why-Nothing-Else-Matters

Science will be used to make all the above happen. The field and its practitioners will be allowed the scraps that fall from those tables and occasionally they will be invited to the banquet itself. A few who know how to play this game will be allowed to stay.

Rob Henry July 14, 2014 at 18:45

Yes Swage, my guess is also that waves of peaceful expansion in space will have threat aversion behind them, even if no one ever acknowledges it. What better way for a consortium of countries to become safe from the military lasers of renegade states than to jointly build and control those banks of Alpha Centauri lasers you alluded to. Others would realise that in an absolute emergence upon which every member agreed these could be redeployed.

ljk July 14, 2014 at 22:19

Something else to consider. If you are spending decades to centuries traveling via lightsail to another star system you better hope the people back home can maintain the beam all that time. One of the disadvantages of not being able to carry your fuel with you or find it along the way.

Eniac July 14, 2014 at 22:40

Gregory Benford: I like your analogy. Is there a reason, though, you left out the wars? There were plenty of them. And the major, if not dominant role that weapons technology played in the conquest of the Americas?

swage July 15, 2014 at 3:28

I don’t think the technology will reap a lot of money (aside of the usual beneficiaries) – not initially for that matter. It requires hefty investments for decades in the first place. But it will pay off eventually in the form of directed-beam-asteroid-mining, so long-therm it will be a huge gain because it opens up the entire asteroid belt for resource operations. You can move the asteroids to earth by radiation pressure, its a very simple concept actually and highly practical. You can even analyze the contends of an asteroid by spectral analysis when firing a beam at it. But you need those beams.

Technically cooperation its practically build into the technology. If multiple countries acquire the technology, as a deterrent, space projects will become important. Now you can speed up those projects by employing more powerful beams, or use more beams. That means teaming up to use the technology, if its under the control of multiple nations gives an advantage. They will be forced into cooperation, not because they want to but because they have to.

Gregory Benford July 15, 2014 at 12:34

Eniac: But I DID SAY “Mexican Wars”… both started by Mexico,y’know, same general: Santa Ana. Classic dumb dictator/general.

Eniac July 15, 2014 at 19:59

Gregory Benford:

Yes you did mention it. Sorry, I overlooked that.

Reading up on the Mexican American War a little bit, though, I get the impression that you mis-characterize it badly. According to Wikipedia, it was started by the US, against a much weaker Mexico in political disarray. Nominally, with the goal of annexing Texas, but with an eye on California and New Mexico, as well.

In addition to the Mexican Wars, there were also many Indian Wars and the Seven Years’ War (French Indian War), which pretty much decided whether North America would become French or English speaking. We know how that turned out, sadly (for the French, that is).

It is likely that any new territory in space will be disputed just as violently as the new American continent was. As soon as it is recognized as valuable, which may take some time.

Gregory Benford July 16, 2014 at 11:42

No, US admitted Texas to the Union, Mexico crossed the Rio Grande in force, fought north, & the USArmy drove it back. Similar to the Texicans routing SantaAna after the Alamo, when he tried to force American immigrants out of the territory.

In taking all that territory, & paying Mexico’s debts too, the US overthrew a defacto dictatorship and opened the west. Calif had 73,000 people in it in 1850. The Mexicans and Spanish had neglected it, while the Indian population dropped ~90%, for centuries.

Eniac July 20, 2014 at 22:40

Interesting how there are still such conflicting views of this war so long after it was over. May everyone read up on it themselves….

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