by Paul Gilster | Jul 10, 2014 | Sail Concepts |
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.’
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.
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.
by Paul Gilster | Jul 9, 2014 | Sail Concepts |
As Cosmos 1 demonstrated, launching solar sails isn’t always easy. The Planetary Society’s sail perished thanks to a malfunctioning Volna booster not long after launch in 2005. When NASA attempted to launch its NanoSail-D in 2008, a problem aboard the Falcon 1 booster destroyed the craft. And when the agency launched the backup, NanoSail-D2, in December of 2010, the CubeSat-based sail failed to eject from the FASTSAT satellite it was aboard. Just when all seemed lost, NanoSail-D2 ejected on its own on January 17, 2011 and deployed its sail soon after.
Now we’re looking at a new Planetary Society venture called LightSail-A, which grows out of the NanoSail-D project and, according to news that should be firmed up tonight, should be ready for launch in the near future. As with Cosmos 1, the funding for LightSail-A was raised from private sources and Planetary Society membership dues, with the spacecraft itself being built by Stellar Exploration Inc. out of San Luis Obispo, CA. With mylar sails 4.5 microns thick, the sail will extend upon deployment to cover 32 square meters. Three CubeSat spacecraft form a ‘bus’ about the size of a shoebox that weighs in at no more than 4.5 kilograms.
Image: The Planetary Society’s LightSail-1 will test out solar sail technologies in Earth orbit as a prelude for later missions including solar storm monitoring at L1. Credit: The Planetary Society/Rick Sternbach.
Back in June, the Planetary Society’s Jason Davis described recent LightSail-A activity:
During the past two years, LightSail has come of age. The solar sail itself demonstrated a full deployment back in 2011, but the guts of the spacecraft were far from mature. Project manager Doug Stetson and his team have been shaking out bugs and overhauling LightSail’s electronics, attitude control, software and communications systems. Next up is a full “day in the life” flight system test on Wednesday, June 4 that includes another sail deployment and full operation of the spacecraft as if it were in orbit. I’ll be on hand at Cal Poly San Luis Obispo to observe and report.
The test in question had to be delayed because of problems involving the TRAC (Triangular Rollable and Collapsible) boom system so crucial in proper deployment of the sail. A breakdown of the three deployment problems the team uncovered is here. Later testing on June 24 showed that fixes for the power anomalies, spacecraft processor overload and other boom deployment issues seem to have worked. Davis has made a video of the June 24 deployment test available; he’s also offering regular updates explaining technical features of the diminutive spacecraft.
The LightSail project involves three craft, the goal of the first being to test deployment and basic operations at an altitude of 800 kilometers. A second mission, LightSail-B, will collect scientific data and demonstrate controlled solar sailing, while a third has the ambitious goal of reaching the L1 Lagrangian point, a useful position from which to detect solar activity producing geomagnetic storms.
At this point it’s always a good idea to distinguish between the phenomenon LightSail-A will be exploiting — the momentum imparted by solar photons — and that other means of ‘sailing’ through space, the solar wind. The sailing metaphor is what can make this confusing. The solar wind consists of particles streaming out from the Sun, moving much slower than the speed of light and offering a push to spacecraft designed to exploit them. So-called ‘magsails’ are under study that could use the solar wind for fast interplanetary transport, but the force from the solar wind is a thousand times less than the photon force a solar sail can draw on in its operations. By ‘solar sailing,’ then, I refer to drawing on the momentum imparted by massless photons.
We’ll know more about LightSail-A’s shakedown cruise this evening, when The Planetary Society hosts a live webcast from 2200-2330 EDT (0200-0330 UTC), billed as the venue for “a major announcement about our solar sail spacecraft.” Expect a tour inside the cubesat and presentations by the engineers behind it, as well as an announcement about its launch. Confusingly, The Planetary Society is referring to its sail as both LightSail-A and LightSail-1, but I suspect that by the time the evening is over, we’ll have the basic nomenclature set.
by Paul Gilster | Jul 8, 2014 | Sail Concepts |
We’re coming up on the tenth anniversary of Centauri Dreams, and it doesn’t surprise me even remotely that two of the earliest stories I ever wrote for the site involve solar sails. August 17, 2004’s Solar Sail Test by Japan talks about the Japanese Institute of Space Astronautical Science testing sail deployment strategies, and the August 14 entry, Cosmos 1 Solar Sail Closer to Launch, briefly describes the privately funded sail that was developed by The Planetary Society’s efforts, with financial contributions from members and major backing from Ann Druyan’s Cosmos Studios.
I’ve been fascinated with space sailing since first encountering the notion in 1960s-era science fiction, particularly Clarke’s “The Wind from the Sun” and Cordwainer Smith’s “The Lady Who Sailed the Soul.” What I lacked back then, though, was an appreciation for the challenge posed by the rocket equation, which demands so much more propellant the faster you want to go. Space missions demand huge mass ratios (the weight of the fueled rocket compared to the same rocket without fuel), and a chemical rocket on a deeply ill-advised Alpha Centauri mission would, to reach the target within a human lifetime, demand an amount of propellant larger than all the mass in the observable universe. Rocket scientists call that sort of thing a ‘showstopper.’
Image: An artist’s conception of Cosmos 1. Credit: Rick Sternbach.
So using solar photons to impart momentum while leaving heavy propellant out of the vehicle entirely makes eminent sense, but it’s been a long, slow road from theory to implementation. We saw yesterday that sail ideas got a serious bump in interest when Jerome Wright, who had been studying sail techniques, began to look into a possible rendezvous mission to Comet Halley, and soon NASA had Louis Friedman’s team hard at work investigating the possibilities. Budgeting issues, a tight schedule and an untested technology accounted for the decision not to pursue the sail mission.
Image: Artist’s conception of the Cosmos 1 sail deployed in orbit. Credit: Cosmos Studios.
We did see what could be described as a solar sail test in 1993, when Russian scientists deployed Znamya 2 from the Mir space station, although Znamya was not a free-flying device and was designed as a thin-film mirror. The idea was to experiment with beaming solar power to the ground, but dealing with large, lightweight reflective material and unfurling it in space makes for a reasonable demonstration of some aspects of sail technology. The Japanese experiments in 2004 involved deployment of sail materials from a sub-orbital sounding rocket.
And I should mention the two communications satellites — INSAT 2A and 3A — launched by India in 1992 and 2003, each of which used sail material to offset the torque from solar pressure on their multi-panel solar arrays. You see, we did have plenty of data about the pressure photons could exert on objects in space — controllers had used vanes mounted on the Mariner 10 spacecraft for attitude control, and Louis Friedman recounts in his book Starsailing: Solar Sails and Interstellar Travel that NASA, experimenting early in the space era with small metal needles launched into the ionosphere to study communications, found that sunlight pressure was a significant factor in their trajectories.
So when The Planetary Society, of which Friedman was then executive director, took up private sail work that had been developed through the World Space Foundation after the latter group’s demise in 1998, it was building on known physics and an idea in need of deployment and testing in space. A suborbital test of the deployment system, using a sail with only two blades, was attempted in 2001, only to fail when the spacecraft did not separate from the Volna booster. The full 100-kilogram spacecraft, built at the Babakin Space Center and the Space Research Institute in Russia, was paired with another Volna, a former intercontinental ballistic missile.
Cosmos 1 was launched on June 21, 2005 from a Russian submarine in the Barents Sea, but failure aboard the booster prevented the spacecraft from reaching orbit. Had it succeeded, this would have been the first orbital test of a true solar sail. The $4 million project was tiny by government space agency standards, but it produced an eight-blade sail, with each blade fifteen meters in length and a total surface area of some 600 square meters. The plan would have been to attain a circular orbit at 800 kilometers, at which point the sail blades would have deployed.
It surely would have been a test as exciting as the Japanese deployment of the IKAROS sail had everything gone according to plan. The deployed sail was to have used the momentum of solar photons to raise its orbit by 50 to 100 kilometers over the course of the 30-day mission. There were also plans to bounce microwaves from NASA’s Goldstone facility of the Deep Space Network off the sail to measure the effect of microwave beaming, the physics of which had already been demonstrated in laboratory work by James and Gregory Benford.
The Cosmos 1 launch failure was hard to take, but the idea of privately funding a significant space mission certainly did not die here, and as we’ll see tomorrow, The Planetary Society has continually renewed the effort to get a craft called LightSail into space in the context of a multi-vehicle project. As the space agencies continue their work, it’s heartening to see the commitment of volunteers and contributors to private projects that leverage public interest in these technologies and show what can be done on shoestring budgets and sheer dedication.
by Paul Gilster | Jul 7, 2014 | Sail Concepts |
We have interesting solar sail news coming up later this week, so it seems a good time to lead into it with some thoughts on NASA’s early solar sail work. For the theoretical work for a sail rendezvous with Halley’s Comet was well along in the 1970s, when Louis Friedman, later a founder and executive director of The Planetary Society, led what would become the first space agency attempt to develop an actual sail mission. Friedman’s interest in and commitment to sail ideas will become apparent as this week progresses and we look at other sail designs.
Much of the impetus for a NASA sail study in the 1970s — a $4 million effort at the Jet Propulsion Laboratory in 1977 and 1978 — can be traced back to Jerome Wright, an engineer at the Battelle Memorial Institute in Ohio. In his book Starsailing: Solar Sails and Interstellar Travel (John Wiley & Sons,1988), Friedman recalls a meeting of the Advanced Projects Group at the Jet Propulsion Laboratory in which he learned about Wright’s newest idea from Chauncey Uphoff, a senior member of JPL’s mission design section. Friedman describes the event:
Then, at the group meeting, Chauncey Uphoff and Phillip Roberts dropped the bombshell. “Jerry Wright has found a possible way to rendezvous with Halley’s Comet,” Chauncey announced.
“You mean fly-by, not rendezvous,” I said.
“No, I mean rendezvous.”
“With a trip time of ten years?”
“Would you believe four years?”
Image: Louis Friedman, former executive director of The Planetary Society and one of its founders, who led NASA’s study of a solar sail mission to Halley’s Comet.
Wright’s book Space Sailing (Routledge, 1992) lays out the basic concepts behind solar sails and the principles behind navigating with a sail in space — it was Wright who first realized that Halley’s Comet’s 1986 appearance in the inner Solar System offered a chance to try the technology out on an actual mission. Wright would be invited to conduct a seminar at JPL on sail techniques in May of 1975 that led to his joining the small team there in December of that year, with NASA’s approval of a study to design a vehicle and mission concept to the comet.
We’ve looked at solar sailing frequently on Centauri Dreams and traced the development of the idea from the first technical paper, Carl Wiley’s “Clipper Ships of Space,” which appeared in Astounding Science Fiction in May of 1951. Wiley, of course, built on ideas dating back to the time of Kepler, with major work accomplished by Konstantin Tsiolkovsky and Fridrickh Arturovich Tsander in the early part of the 20th Century. It’s interesting to learn from Friedman’s book that Wiley, then working as an engineer at Rockwell, came to some of the technical presentations at JPL as the Halley’s Comet idea was discussed.
Friedman credits Ted Cotter, working at Los Alamos, with the first presentation of a spinning sail. See A Sail Mission Emerges for more on Cotter’s ideas, and be aware that his 1958 memorandum “An Encomium on Solar Sailing,” distributed internally at Los Alamos, is now online. Spinning the sail helps because it allows the sail to be stabilized without the help of an external structure. I should also mention Richard Garwin, whose paper on solar sails that same year led to a lifetime of interest in the concept. Friedman credits Garwin with helping to inspire NASA’s later interest in a sail mission, leading NASA administrator James Fletcher to commission studies on sails that were assigned to Jerome Wright during his days at Batttelle.
So we can see a flurry of sail interest in the agency in the mid-1960s — an early meeting on solar sail design was actually held at NASA’s Langley Research Center as early as 1960 — but with the end of the Apollo missions, a dwindling space program had no plans for specific missions. Thus at the time Jerome Wright began talking about a Halley’s Comet mission in the mid-1970s, little other work was being done on sail technologies. Wright was more or less the only game in town.
Friedman recalls the situation:
Then Wright found the Halley rendezvous opportunity. By the time the JPL study team began its task, two major developments had occurred. First, NASA was developing the space shuttle, which promised to carry large-volume payloads into orbit. Second, there had been great advancements in the technology of deploying huge structures in space. The shuttle also made it possible for scientists to test space concepts, and the JPL study team hoped to test the solar sail from a shuttle in orbit.
The positive results of the 1976 and early 1977 JPL studies captured the imagination of the new director of the Jet Propulsion Laboratory, Dr. Bruce Murray. With his approval, the study team made a major effort to put together a project plan for a rendezvous with the comet. This work, however, had to be done rapidly. In order to launch in late 1981, the project would have had to start moving by the end of 1978. 1 was put in charge of the study and we quickly wrote a proposal for a one-year study and gave it to NASA.
The original NASA design called for a sail of 800 meters to the side supported by four diagonal cross beams, to be launched by the Space Shuttle in 1981. But in 1977 a ‘heliogyro’ approach invented in the mid-1960s by Richard MacNeal and John Hedgepath won out, featuring 12-kilometer long sails made up of narrow strips that would spin up like helicopter blades to keep the sail rigid. Unlike the earlier design, the heliogyro could use centrifigual force from its spin to unreel the blades from storage drums, thus requiring no human assembly in orbit.
Image: An artist’s conception of the Halley’s Comet heliogyro design. Credit: JPL.
NASA’s acceptance of the proposal led to the design study that brought in industrial contractors, included support from NASA Ames and Langley, work that resulted in the conclusion that solar sailing was indeed feasible. The question, though, was whether it was practical to speak in terms of a Halley’s Comet rendezvous given the time constraints involved. NASA would ultimately turn down the proposal as being based on a technology that was not sufficiently mature. When I asked Dr. Friedman about this at the last 100 Year Starship symposium, he said NASA was probably right. The Halley’s sail was pushing too far, too fast for its time.
Cost was a factor as well, with a price tag estimated at $500 million — remember the budgetary morass NASA found itself in with Space Shuttle cost overruns in this era. Other comet missions were considered, but in the end the United States did not launch a dedicated mission to Halley’s Comet. The story of comet rendezvous, the Giotto mission from ESA, the Soviet Vega spacecraft and the Japanese Suisei and Sakigake probes, makes for fascinating reading, but in terms of solar sails, it would be a long wait before JAXA’s IKAROS sail took flight in 2010. Before then, though, Louis Friedman would be involved in other attempts, one of which we’ll discuss tomorrow.
by Paul Gilster | Jul 4, 2014 | Culture and Society |
Michael Michaud gave the speech that follows in 1988 at the 39th International Astronautical Congress, which met in Bangalore, India in October of that year. Reading through it recently, I was struck by how timely its theme of spaceflight advocacy and human expansion into the cosmos remains today. When he wrote this, Michaud was director of the Office of Advanced Technology for the US Department of State, though he reminded his audience that the views herein were his own and not necessarily those of the US government. Michaud’s support of spaceflight and his determinedly long-term approach to our possibilities as a species has distinguished his space writing, which has been prolific and includes the essential Contact with Alien Civilizations
(Copernicus, 2006). Although I had thought of updating some of the references below, it seems unnecessary. What counts are the themes. Working well before the recent surge in interstellar interest, Michael here explains why humans need to develop and strive for goals among the stars.
by Michael A.G. Michaud
The history of astronautics is not only a history of scientific and technological progress, but is also a history of persuasion. Advances in astronautics have sprung not only from steady technical advance, but also from advocacy, led by individuals and groups with deep-seated motivations. Those advocates, while often frustrated in the near term, laid the philosophical and cultural foundations that helped speed the coming of the Space Age.(1)
While many justifications have been put forward for space activities, two motivations have consistently underlain the leading edge of the space advocacy: the exploration of the universe around us, and human expansion into it. Throughout the history of astronautics, other motivations have appeared and disappeared, but these two always have been identifiable.
The Spaceflight Advocacy
The Spaceflight advocacy began with visions and ideas, initially in science fiction. Serious theoretical work began with Konstantin Tsiolkovski in the late l9th and early 20th centuries. Hermann Oberth and Robert Goddard further developed the theoretical structure necessary for spaceflight. Initial rocket experiments were conducted by Goddard and others in the United States, by members of the Verein Fur Raumschiffahrt in Germany, and by members of rocket societies in the Soviet Union. The VFR in Germany, the American Interplanetary Society in the United States, and the British Interplanetary Society were advocating interplanetary travel in the early l930’s. Yet rockets of significant scale were not launched until World War II. Despite far-seeing work such as the 1946 RAND study(2), the use of the rocket to enter space had little political support in the 1940s. Yet, a decade later our machines had entered space to stay, and two decades later we landed humans on the Moon.
The original space advocacy, directed toward exploration and expansion beyond the Earth’s atmosphere into cislunar space and later into the solar system, has been spectacularly successful. By 1989, our unmanned spacecraft will have visited every planet in our solar system except Pluto. Both the Soviet Union and the United States — with its allies — are establishing a permanent human presence in low Earth orbit. The industrialization of near-Earth space has been conceptualized since the early 1970s, and the idea of human colonies in free space has been shown to be technically feasible. Advocacies have crystallized around the long-visualized Moon Base and manned mission to Mars; though neither goal has been achieved yet, it is widely expected that both will be early in the 21st century. The U.S. National Commission on Space has proposed an elaborate space transportation infrastructure linking the Earth to the Moon and Mars.(3) We are well advanced in exploring the solar system, and are close to expanding into it.
A major symbolic turning point occurred in February, 1988, with the release of a new U.S. national space policy document. That document committed the United States to a new long-term goal: the expansion of human presence and activity beyond Earth orbit into the solar system.(4) This had been a goal of the spaceflight advocacy for many years, identifiable implicitly in the writings of Tsiolkovski and explicitly at least as far back as the 1920s. In two to three generations (depending on the starting point one chooses), the spaceflight advocacy had won a policy endorsement that would have seemed inconceivable to any but its most optimistic original members: the expansion of the human species outward from Earth.
The Interstellar Advocacy
In recent years, we have seen a small but active advocacy for interstellar flight. In many ways, the interstellar advocacy of today is similar to the spaceflight advocacy of the 1920s and the 1930s. Dedicated and believing that what it advocates is not only right but inevitable, the members of that advocacy are doing the theoretical work and are laying out plans for interstellar exploration and travel. However, they lack the credibility needed to win funding and political support for their proposals.
Like the spaceflight advocacy, the interstellar advocacy first appeared in science fiction, in the 1930s and 1940s. The first significant non-fiction paper was published in 1950.(5) Scattered works appeared during the next two decades, but it was not until the mid-1970s that the interstellar advocacy achieved some public recognition. Landmarks were Forward’s paper “A National Program for Interstellar Exploration,” published in 1975, and the British Interplanetary Society’s Project Daedalus study, published in 1978.(6) Papers on the theory and technology of interstellar flight began to appear more frequently, particularly in Astronautica Acta and the interstellar studies issues of the Journal of the British Interplanetary Society. The literature grew to the point that bibliographies were published.(7) Yet the number of advocates remains small, the literature still is specialized and narrowly circulated, and political and financial support is essentially non-existent.
The interstellar advocacy has reflected both the motivation to explore our larger environment and the motivation to expand human presence and activity beyond our solar system. Many of the proposed missions, particularly the early ones, are unmanned probes of nearby star systems. Others are missions of manned exploration, and still others are explicitly intended to carry human colonists to other systems, beginning the human colonization of the galaxy. None of these missions are known to be on the agenda of any space agency. However, more modest precursor missions have been proposed, such as an extrasolar probe, an Oort cloud mission, or the Thousand Astronomical Unit probe, which are extensions of existing solar system exploration technology.
In its 1988 report titled Space Science in the 21st Century, the Space Science Board of the U.S. National Academy of Sciences endorsed an interstellar probe. The Board envisioned a spacecraft that would escape the solar system at a velocity of about 80 kilometers a second, and enter the interstellar medium within 10 years. Such a spacecraft, if launched in the year 2000, would pass the Pioneer and Voyager spacecraft new proceeding slowly toward the stars.(8) This endorsement would have been inconceivable only a decade earlier.
The interstellar advocacy is not yet taken seriously by the opinion leaders of any nation, and has yet to win support from any government. That advocacy might do well to reflect on the history of the successful spaceflight advocacy, which took decades to sell its ideas, and only won success in stages. Its progress was not smooth, but was marked by raised hopes and disappointments, starts and stops. Political events and cultural change had significant impacts on the process. The advocacy could not force events beyond what was known of the physical environment and foreseeable technology at any given time. Yet it succeeded in transferring its aspirations to many people, and in eroding conceptions of what was not possible in others. Many of its views have been adopted by the governments of major nations, and are part of popular culture.
The Larger Context
Both the spaceflight advocacy and the interstellar advocacy reflect larger paradigms of human exploration and expansion.(9) We humans, who have explored and expanded into new environments on Earth, have nearly completed our initial reconnaissance of the solar system, and are on the verge of expanding into it. The day may come when we find the solar system as limiting to our aspirations as the Earth was thirty years ago. We will look outward into an even larger environment, sprinkled with stars and planetary systems. We will explore the nearer parts of the interstellar environment through space-based astronomy and unmanned probes. Then, with our improved knowledge of that environment, our improved technological capabilities, our expanded economic base, and our changed point of view, we may choose to continue the expansion. With that decision, we will assure that humans and their cultures will free themselves of dependence on one star, as they are now freeing themselves of dependence on one planet,
This vision will not be accepted easily by the public — even the informed public. While some individuals accept the outward-looking paradigms of exploration and expansion, most do not, and must be persuaded in stages to at least tolerate such ventures. If the advocacy of interstellar exploration and colonization is to succeed, it must have a long perspective, and must maintain a certain degree of continuity. Yet it also must be ready to seize on events that will speed the coming of interstellar flight. In doing so, it will demonstrate a continuity with the spaceflight advocacy that rests on the shared aspirations of exploration and expansion.
A Manifesto
Humanity should adopt expansion beyond Earth as a major organizing theme for its future. Evidence is strong that life tends to expand into new ecological niches when that is possible, and that such expansion is advantageous for the species. Expansion opens new opportunities for evolution and diversification, and for access to larger resources of materials and energy. Space is the macro-environment for life, the ultimate extension of our ecological range.
Exploration precedes expansion. Even more than the other forms of life we know, humans are motivated to expand by their improving perceptions of their larger environment. They deliberately explore the larger environment of space in the belief that they will benefit from improved knowledge. Astronomy and the unmanned exploration of space are allies of human expansion.
We should be conceptualizing the expansion in stages. The rate of human expansion is constrained by our perceptions, by our technologies, by our economic and human resources, and by our cultures, particularly by the predominant conceptions of what is possible. While there is a growing perception that a permanent human presence on the Moon and the human exploration of Mars are feasible, the creation of a solar system civilization still seems beyond our reach. In the early stages of developing a solar system civilization, we may reject the idea of human interstellar flight: later, with an expanded economic and technical base and greater confidence in our abilities, interstellar voyages will seem more feasible. Each stage will grow from the perceptions and capabilities created in the preceding stage.
Humanity needs to develop the technologies of expansion. Humans dreamed of voyages beyond the Earth for centuries, but could not accomplish those dreams until the technologies of the 20th century made them possible. Without telescopes, we would not have been tantalized by Mars; without rocketry, we could not have seen it in detail; without improved life support systems, we will not be able to journey there ourselves. Technology enables expansion.
Expanding into the Galaxy is an appropriate long-term goal for humanity. To rise above their intra-species disputes, humans need purposes that transcend their divisions. The expansion of humanity outward from the Earth and later outward from our solar system would be a grand shared enterprise for humanity, extending over many generations and giving us a long-term continuity of purpose.
Human expansion will require a continuity of intelligent advocacy. While the drive to expand is strong, cultural values vary with time and place, and the degree of support for expansion will vary with them. At each stage of the expansion there will be arguments against the next stage, which will be called too expensive or impractical; there also may be arguments against expansion because of our own moral imperfection. Advocates will be needed at every stage.
Conclusion
Astronautics already has brought great benefits to humanity, in our ability to communicate with each other, to navigate safely, to preserve the peace, to observe the Earth and the atmosphere, to study the solar system, the Galaxy and the Universe, and to perceive of ourselves as a species. Implicit in astronautics is the idea of expansion, which will bring benefits we can only dimly perceive today. Some have sensed all along that astronautics is linked to our destiny as a species.
We who are advocates of spaceflight, of interplanetary flight, and of interstellar flight are part of a great continuity. We are expressions both of powerful human drives and of an intellectual tradition. We have an endless mission before us, one marked by a succession of stages in which resistance, doubt, and delay must be overcome. Now that the first Spaceflight Revolution is behind us, we have reached a stage of maturity in which we can consciously decide and declare our intent to be human expansionists. We should not be embarrassed to be advocates of human expansion; we should be proud.
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References
1. For studies of the spaceflight advocacy, see William S. Bainbridge, The Spaceflight Revolution, New York, John Wiley and Sons, 1976; Frank H. Winter, Prelude to the Space Age: The Rocket Societies, 1924-1940, Washington, D.C., Smithsonian Institution Press, 1983; Michael A.G. Michaud, Reaching for the High Frontier: The American Pro-Space Movement, 1972-1984, New York, Praeger, 1986.
2. Report Number SM-11827, Preliminary Design of an Experimental World-Circling Spaceship, May, 1946.
3. National Commission on Space, Pioneering The Space Frontier, New York, Bantam, 1986.
4. White House Fact Sheet on Presidential Directive on National Space Policy, February 11, 1988.
5. Leslie R. Shepherd, “Interstellar Flight,” Journal of the British Interplanetary Society, Volume 11 (1950), Pages 149-55.
6. Robert L. Forward, “A National Program for Interstellar Exploration,” in Future Space Programs 1975, a compilation of papers prepared for the Subcommittee on Space Science and Applications of the Committee on Science and Technology of the U.S. House of Representatives, Volume II, Washington, D.C., U.S. Government Printing Office, 1975, pages 279-326; Project Daedalus: The Final Report on the BIS Starship Study, supplement to the Journal of the British Interplanetary Society, 1978.
7. For example, see Eugene F. Mallove, Robert L. Forward, Zbigniew Paprotny, and Jurgen Lehmann, “Interstellar Travel and Communication: A Bibliography,” Journal of the British Interplanetary Society, Volume 33 (1980), entire issue.
8. Space Science Board, Space Science in the Twenty-First Century: Imperatives for the Decades 1995 to 2015 — Overview, Washington, D.C., National Academy Press, 1988, page 34.
9. For further elaborations by this author on the theme of human expansion, see Michael A.G. Michaud, “Spaceflight, Colonization, and Independence,” Journal of the British Interplanetary Society, Volume 30, Number 3 (March, 1977), 83-95 (Part One); volume 30, Number 6 (June, 1977), 203-212 (Part Two); Volume 30, Number 9 (September, 1977), 323-331 (Part Three); Michael A.G. Michaud, “The Extraterrestrial Paradigm,” Interdisciplinary Science Reviews, Volume 4, Number 3 (September, 1979), 177-192; Michael A.G. Michaud, “Four-Dimensional Strategy,” in Jerry Grey and Christine Krop, Editors, Space Manufacturing Facilities 3: Proceedings of the Fourth Princeton /AIAA Conference, New York, American Institute of Aeronautics and Astronautics, October 31, 1979, 49-61; Michael A.G. Michaud, “Improving the Prospects for Life in the Universe,” in William A. Gale, Editor, Life in the Universe: The Ultimate Limits to Growth, Boulder, Colorado, Westview, Press, 1979, 107-117.
