A Joint Tau Zero Foundation and British Interplanetary Society Initiative

You will probably have heard of the old tradition (before GPS!) of using the stars to help navigate around the earth especially at sea.  But when you’re actually travelling among the stars, and they are no longer ‘fixed’ in the sky, how would you navigate then?  This was the question asked by the Daedalus team in the 1970s as they planned their flight out of the solar system to Barnard’s star.  Despite noting that the interstellar probe presented problems of navigation far beyond those that had to be solved for the current interplanetary probes,  their original investigation concluded that there were no fundamental problems that could not be overcome through the normal process of technological development.  So one might ask what has happened over the last 30-40 years and what are the implications for the Icarus Team?

Those fundamental issues were discussed in the original Daedalus navigation paper but if you don’t want to search out your historical JBIS here are the main conclusions: they determined that an angular measuring accuracy of a microradian or so (0.2” – arc seconds) and a 5 metre telescope using sensors in the visible to thermal bands (0.5-100 micrometres) would do the job.  But there was a caveat that currently known stellar positions were not accurate enough for interstellar navigation although they supposed that this problem would be resolved by taking astrometric observations from Daedalus flight trails.

Well, in the first instance let’s check out one of the most recent missions that might offer some comparison …The NASA New Horizons Mission to Pluto and the Kuiper Belt.  The guidance and control system on New Horizons is capable of providing attitude knowledge to better than +/-471 microradians.  That relates to how accurately you can point your communications system back to earth; there’s more on this in the earlier blog by Pat Galea.  The Daedalus paper stated 250 microradians would suffice for this during its cruise phase so at least it is getting close to that requirement.  Interestingly, Galileo Avionica, the manufacturer of the star trackers often used for guidance and control in interplanetary missions including New Horizons, states the accuracy of their A-Str star tracker as better than 10” which is about 48 microradians.  So, still not that near the requirements set out by the Daedalus study.  Perhaps that was good enough for navigating around the outer solar system so hence there was no real need to go for greater accuracy.

Suppose we take a look at a mission specifically designed for accurate stellar measurements such as the ESA Hipparcos mission in the 1990s?  Hipparcos was designed to measure stellar parallax (and positions) using a main mirror of only 29cm…In this case the error was given as between +/-0.7 to 0.9” (for star magnitudes down to the 8^th magnitude).   That’s not a whole lot more than a microradian.  The follow-on ESA mission of Gaia promises even greater accuracy albeit with larger mirrors.  So it seems that the Daedalus team were correct in their assumption and sufficiently accurate systems are now possible.

You might recall that the Deadalus mission profile was to carry out a fly-by of the target system and the only complication was for the sub-probes to not fly too close to the targets (remember the fly past velocity was to be 12% of the speed of light – if you get too close the relative motion becomes too great).  Interestingly, it now looks possible that Icarus may include some deceleration or perhaps some elements might even go in to orbit which will remove some of the problems identified by the Daedalus team but will add a significant amount of complexity to a fully automated system.  In the near future and with the plans for exoplanet detection it is likely that there will be another advantage for Icarus: that of having prior knowledge of the planetary system before it sets off.  Indeed, there are some concerns that by the date of a possible Icarus launch/arrival at the target, future solar system based observations may well exceed the capability of the Icarus onboard systems until the probe gets quite close, but at least that will mean there would be a high level of knowledge about the target system.

This all sounds fairly promising for the Icarus study and there is more good news.  Recent studies have been made into using x-ray pulsars to help navigate space.  In effect, the suggestion is that by using 4 x-ray pulsars and their precise timing signals then you can effectively set up an interstellar GPS system.  You can find more information about this at http://www.centauri-dreams.org/?p=136. 

Finally, after all that promise from developments of the last 30-odd years there still seems to be one nagging thought that was also raised by the Daedalus team…how are we going to make the system reliable enough to last the anticipated mission time i.e. perhaps 50-70 years!  Modern star trackers are rated for around 15 years although some spacecraft out there, for example the Voyagers, are already over 30 years old and still under guidance and control and still expected to go on for another 10 years! 

So there is real hope and the Icarus team will be taking on the challenge of all these issues for their new interstellar design.  The review of the navigation problem will consider all the relevant assumptions of the Daedalus team and will be taking a closer look at the technology and the real missions that can be related to it.  Overall, it seems possible that rather than leaving it to any future technological development Icarus may be able to use current technology and meet the requirements for interstellar navigation.  But, as my partner, Sue always says, if all else fails we could always stop and ask for directions!

Next time I shall take a look at the scientific benefits of sending a probe to the nearest stars with specific reference to a related navigation issue raised by Project Daedalus: improving the accuracy of measuring stellar positions and distances and how it could help calibrate the scale of the universe.

References:

Fountain, Glen H., et al, ‘The New Horizons Spacecraft’, arXiv: 0709.4288v1 (26 Sep 07)

Perryman, M.A.C. et al, ‘The Hipparcos Catalogue’, Astron. Astrophysics, 323, L49-L52, (1997)

Richards, G.R.  ‘Daedalus Project: The Navigation Problem’, JBIS, ppS143-148, (1978)

One of the paramount issues for interstellar exploration is the attainment of adequate velocities that make reaching star systems in a matter of years or decades a realistic possibility. For interstellar explorers of the future, antimatter may prove to be an invaluable tool that has the capability to make the universe slightly more accessible.

 This is the first of several articles on antimatter and how it can be utilized for the purpose of space exploration. In this first article we’ll focus on production and storage, and in future articles explore the type of rockets that could use antimatter and even look into the prospect of using antimatter to catalyze fusion reactions.

 What makes antimatter a particularly tantalizing fuel source is its almost unfathomable energy density. It is, simply put, the most efficient fuel source known to physics. This is neatly explained in, quite possibly, the most famous equation of all time, E=mc², an expression of the inherent energy contained within all matter. As a simple example, 1kg of matter contains 9×10^16J of energy, or in simpler terms, about five tonnes of antimatter would theoretically be enough to fuel all the world’s energy consumption for a single year.

 The following illustrates a comparison of three energy generation mechanisms and their efficiences in terms of extraction of energy for a given unit off mass.

Fission:~0.0009
Fusion~0.004
Antimatter: ~1.0

 It was the physicist Paul Dirac who, in 1928, while researching the relativistic Schrödinger equation, appreciated that a solution to the equation existed which allowed for the existence of ‘negative matter’, or more specifically, a positive electron now commonly called a positron. The positron was first detected experimentally in 1932 by the physicist Paul Anderson while conducting cloud chamber experiments. Positrons are now routinely created and utilized frequently in the medical field, albeit in relatively minute quantities insufficient for propulsion.

 Two difficult problems must first be overcome before antimatter can be put to use as a fuel source. The first is the creation of antimatter in sufficient quantities, next is the storage of antimatter.

 Before addressing the more fundamental problem of creation, it’s instructive to begin with the question of storage. Although positrons (anti-electrons) are relatively easy to create, they are not easy to store in large quantities. By their very nature, positrons are positively charged and therefore exert a Coulombic force of repulsion against one another. This Coulombic force is extremely powerful and only the smallest amounts of positrons can be stored adequately with current technology.

 Because of this, the ideal storage situation would be the case of neutral  antimatter, that is, antimatter with no net charge. This could be most simply realized with the creation of antihydrogen, a stable and energetically bound atom consisting of a single positron and antiproton. A few hundred thousand antihydrogen atoms were produced at CERN in 1995. By their very nature, antihydrogen atoms will annihilate the walls of any container they are stored within. For this reason, specially constructed magnetic storage devices called Penning traps must be utilized. These devices are not suited for high density storage of antimatter that would be required for space propulsion.

 One possibility might be to store antihydrogen in the form of a Bose Einstein Condensate (BEC), a fifth state of matter (BEC, solid, liquid, gas, plasma) first predicted to exist in the 1920’s. When matter is cooled to a low enough temperature, its macroscopic state can be modeled by a single quantum wave function and individual atoms lose their independent identities. BEC’s were first created experimentally in the mid-90’s and are currently an active research area. In this state, Antihydrogen becomes much easier to store [1].

 With regards to the question of production, current methods utilized at CERN are prohibitively expensive and generation of antihydrogen in quantities that would be valuable to spaceflight would cost trillions of dollars. Despite this, it’s important to recognize that CERN is not a dedicated antimatter production facility and that antihydrogen production is a remarkable, yet tertiary goal of the facility. According to recent research [2], a low-energy antiproton source could be constructed in the USA at a cost of around $500M over a five year period, and would be an important first step for mass production of antimatter. However the overall roadmap for antimatter propulsion would involve timescales closer to 50 years.

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

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

 [1] Michael Martin Nieto et al  “Dense antihydrogen: its production and storage to envision antimatter propulsion,” J. Opt. B: Quantum Semiclass. Opt. 5, 2003.

 [2]. Michael Martin Nietoa, Michael H. Holzscheiterb, and Slava G. Turyshevc  “Controlled Antihydrogen Propulsion for NASA’s Future in Very Deep Space1,” NASA/JPL Workshop on Physics for Planetary Exploration, 2004.

“Space is big. You just won’t believe how vastly, hugely, mind-bogglingly big it is.” – Douglas Adams, The Hitchhiker’s Guide to the Galaxy

If our current understanding of physics is correct, then the speed of light in a vacuum sets an upper limit to the speed of any matter or information transmission system. This speed of light (represented by scientists and engineers with the letter c) is about 300 million metres per second. That means a beam of light can go around the Earth’s equator seven times in one second. Yet despite this seemingly phenomenal speed, the time it takes for light to travel between the nearest stars to us is measured not in seconds, days, or even months, but years. That’s why for convenience we measure the distances to stars in units of “light years”. One light year is the distance that light will traverse in one year. The nearest star system to us, Centauri, is just over four light years from Earth.

When we send a craft to another star, we want to get the data from it back to Earth. There are several ways we could do this:

1. Send another small probe back to Earth carrying all the data.

2. Use radio signals.

3. Use optical signals.

4. Use an exotic technique.

Option 1 isn’t as absurd as it might seem. Although the message probe would take a long time to get back to Earth, it could carry a huge amount of data. In network engineering terms, it is “high latency, high bandwidth”. That is, you get a lot of data, but it takes ages to get it. (This is analogous to the often used example of sending a truck full of data DVDs to a recipient. In some circumstances, this may be the optimal way to send the data, if the initial waiting time isn’t a problem.)

However, the additional mass of an extra interstellar probe together with its propulsion and auxiliary systems probably rules it out as a practical solution for most missions.

Option 2 is an extension of the systems that we currently use on our space probes. Radio is just a longer wavelength of electromagnetic wave than light, and travels at the same speed as light. Radio is a great method for generating and receiving signals because it is easy to create using electronics, it can be piped around systems using wires (or for microwaves, tubes), and it can be easily reflected using metal dishes, allowing effective focusing of signals.

The drawback with radio is that the beam spreads significantly over longer distances, with the result that there is less signal power available at the receiving end, unless the receiving antenna is made very wide to catch as much of the signal as possible. The higher the frequency of the radio signal, the less the beam spreads with distance. Over the decades, space communications have indeed used higher and higher frequencies to reduce the beam spreading, with the result that the transmitter on the craft can use lower power while maintaining the same amount of power received at Earth.

For interstellar distances, the beam spreading at radio frequencies is enormous. The Project Daedalus team came up with two ways to make the use of radio signals viable over the terrific distances involved:

a. Make the engine’s reaction chamber be a parabolic dish shape. When the boost phase has ended, use this dish as an enormous reflector to focus the radio transmissions back to Earth.

 b. On Earth (or in near-Earth space), set up a huge array of parabolic dish receivers. (An array of receivers is almost as effective as a single receiver of the same size as the array.) This allows much more of the signal to be picked up than would be possible with just a single large dish. (The design was based on the proposed Project Cyclops, which was to be used to search for signals from extra-terrestrial intelligence.)

Option 3 is really just an extension of option 2, because light is just a much higher frequency radio wave. However, in practice the way it interacts with matter, and the way we create, manipulate and receive it is different enough from radio that we generally treat it separately.

As stated above, beam spreading decreases for higher frequency radio waves. This is particularly noticeable with laser light. If you’ve ever played with a laser pointer, you’ll know just how tight the beam is; shine the dot onto a distant wall, and the dot appears no bigger than if you’d shone it on your own hand, and the dot is about the same brightness.

Lasers are very likely to become more common on future deep space probes to distant parts of the solar system because they enable a much higher bandwidth of data to be sent back to Earth for the same amount of power as a radio system.

Over interstellar distances, despite the fact that lasers create a very tight beam, the beam spreading does cause a problem. The laser also has to be aimed very accurately, and this aim has to be maintained. The tiniest amount of jitter in the craft could cause the beam to miss the target completely. This would be a very tough engineering challenge, combining navigation (so that the craft knows exactly how it is oriented, and exactly where the target is) and control (so that it is actually able to point the laser accurately at the target).

Option 4 covers a range of suggested techniques which either use new methods of transmission altogether, or use existing systems in a new way to increase their effectiveness. 

Claudio Maccone has suggested the use of gravitational lenses to focus radio (and light), drastically increasing the amount of signal power received from the distant craft. The idea is to have two craft, one at the distant star, and one at our Sun. Each craft sits on the far side of its star on the line joining the two craft and the two stars. (So the system is arranged thus: Receiver Craft – Sun – Interstellar Space – Star – Transmitter Craft.)

The two craft have to be beyond a certain distance from their respective stars; this is the focal distance. In the Sun’s case, this distance is about 700AU (i.e. 700 times the distance from the Earth to the Sun). The transmitting craft sends its data, which is gravitationally focused by its star and sent across interstellar space. Years later, this signal arrives at our Sun, which similarly gravitationally focuses it, and is picked up by the receiving craft. This system is effectively using the two stars as lenses in an interstellar telescope.

There is nothing particularly outrageous about this suggestion. It is fully consistent with the laws of physics, but the big challenge here is in engineering. The two craft need to be kept exactly in line with each other and their stars to a very tight tolerance.

Other suggestions for ‘exotic’ techniques include using gravitational waves or neutrinos to send data. The problems here generally come with difficulties in generating and/or receiving the signals. Creating strong gravity waves would, as far as we know at the moment, require a feat of astrophysical engineering (manipulating large blobs of very dense matter). Neutrinos are easier to create, but they are very hard to detect. It is unlikely that any of these exotic techniques will be implemented in a practical system in the near future.

It is heartening to remember that back in 1977 the Project Daedalus team considered the problem of interstellar communications in detail, and concluded

“We do not need technological breakthroughs in this area. Development of the system could begin now.”

In the early 21st century, we can hope to do at least as well as Daedalus.

References:

The Hitchhiker’s Guide to the Galaxy, Douglas Adams, 1979 [Wikipedia]

Project Cyclops [Wikipedia]

Deep Space Optical Communications, Ed. Hamid Hemmati, Wiley-Interscience, 2006 [Google Books Preview]

Deep Space Flight and Communications: Exploiting the Sun as a Gravitational Lens, C. Maccone, Springer-Praxis, 2009 [Google Books Preview]

Updating the Gravitational Focus Mission, P. Gilster [Centauri Dreams]

The Gravitational Lens and Communications, P. Gilster [Centauri Dreams]

Project Daedalus: The Vehicle Communications System, A.T. Lawton and P.P. Wright, JBIS, pp. S163-171, 1978. [CD-ROM]

There are many proposed schemes for interstellar travel. These range from experienced based chemical fuels to highly speculative proposals such as the space drive. So when Project Icarus was put together, why did the team settle on ‘mainly fusion based propulsion’ in the Terms of Reference for the study? It is useful to spend some time justifying the motivation behind this decision.

Firstly, it is necessary to understand some of the history of how Project Daedalus came about. It is generally accepted that the nuclear pulse propulsion scheme as proposed by Project Orion was demonstrated to work in principle. In other words, the Orion team produced a credible engineering design with most of the physics problems solved. What prevents something like Orion from becoming reality of course is the existence of several international treaties. In his autobiography ‘Disturbing the Universe’ the physicist Freeman Dyson clearly argues that today he does not support the propulsion scheme as proposed by Orion:  “Sometimes I am asked by friends who shared the joys and sorrows of Orion whether I would revise the project if by some miracle the necessary funds were suddenly to become available. My answer is an emphatic no…..By its very nature, the Orion ship is a filthy creature and leaves its radioactive mess behind it wherever it goes…..many things that were acceptable in 1958 are no longer acceptable today. My own standards have changed too. History has passed Orion by. There will be no going back.”

Other than Orion, there are several other propulsion systems which are potential candidates for the first missions to the stars. However, when one examines the potential performance and practicality of these different options objectively very few emerge as credible in the near term. This includes nuclear pulse propulsion and in particular either the continuous fusion or the pulsed fusion drive is desirable solutions. The pulsed fusion drive was used in the Daedalus design and uses a high intensity laser beam or electron driver to produce repeated detonation of fusion fuel pellets for thrust generation. The concept has been investigated thoroughly over the years from the work done on Project Orion through to extensive research on pulsed micro-explosions in the early 1970s. Hence, the physics of this type of propulsion scheme is understood sufficiently to enable confidence in any performance estimates for space applications. It is just the technology that is not yet mature.

An ideal requirement for a deep space propulsive engine is the use of lightweight but energetic (high yield per unit mass) fuels. The fusion reaction of hydrogen isotopes comes out on top. A fission rocket is also credible but produces mass-energy conversion with a lower efficiency than for fusion reactions, as well as producing substantial radioactive products. Similarly, antimatter rockets also offer potential with a much greater mass-energy conversion than fusion, but the reaction products are difficult to direct for thrust and the production and storage of large quantities of
antimatter is still a technical challenge. The ideal rocket would be a pure photon rocket.

Fusion propulsion (and the more generic nuclear pulse scheme) offers advantages in performance that far outweigh other propulsion schemes. This includes a range of T/W ratio where in particular a low T/W of around .0001 is possible with very high exhaust velocities of around 10,000 km/s. Also, low mass ratios with very high specific impulse of up to a million seconds appear credible. The use of D/He3 reactions would seem to be the most promising fuel although other fuels such as D/T have potential.  This sort of performance level would be required in order to reach any of the nearest stars within an approximately twelve light year radius in under a century. A fusion rocket which didn’t carry its own fuel would be even better and this has been proposed historically in the guise of the Bussard interstellar ramjet. The problem with this scheme however is achieving the fusion ignition of interstellar high flux ions or atomic hydrogen which has a smaller reaction cross section than hydrogen isotopes. Also, the drag of the spacecraft is proportional to the velocity, and a high velocity is required in order to collect sufficient matter using the magnetic scoop. Ensuring that the overall drag remains less than the thrust of the spacecraft is a technical challenge too.

Most space propulsion systems can be classed into two categories. The first is those that are power limited and although can produce a high specific impulse and high exhaust velocity it is at low thrust. Electric rockets come under this category. The second is those that are energy limited and although can produce a high thrust with high exhaust velocity it is at the cost of a short specific impulse. Both Chemical and nuclear rockets come under this category and this is mainly because the fuel will get burned too quickly. Fusion propulsion offers the advantages of both categories with good propellant utilization. The concept of a fusion based drive is not limited to theoretical studies.

Already an engine is in the process of being developed for Mars missions called the Variable Specific Impulse Magnetoplasma Rocket (VASIMR) which is essentially a scaled down fusion demonstrator engine if improvements in the power, shielding and field control were made. This engine offers the potential for bridging the gap between high thrust-low specific impulse technology as used in conventional rockets and low thrust-high specific impulse technology as used in electric ion engines and it can function in either mode. Similarly, for a full-up pulsed fusion engine, the employment of different pellet sizes also allows a tailoring to the amount of thrust needed for each pulse cycle, with some of the emitted energy being bootstrapped to run the next cycle.

The physics of fusion research has moved forward dramatically in recent years with the US National Ignition Facility now operational and others such as Laser MegaJoule in France under construction. Fast ignition proposals such as HiPER are also under consideration. The chances for scientists finally solving the ‘fusion problem’ are greatly increased. With this in mind, thinking about the implications to a deep space missions is timely. It is quite possible that the demands of a fusion based drive will necessitate a sophisticated space based infrastructure for resource acquisition, processing, manufacture and construction. Especially if He3 mining of the gas giant Jupiter or even the Moon is considered. However, as a theoretical exercise in the application of science and engineering Project Icarus has a large amount of intrinsic worth.

There is another reason why fusion was chosen as the main propulsion engine. Daedalus was a historical design study that changed perceptions about what was possible with interstellar flight. When thinking about performing a design study for an interstellar craft, instead of starting from scratch with an unfocussed ‘anything goes’ design philosophy, it is arguably more useful to build upon the good work that has already been done, essentially standing on the shoulders of the previous generation of designers. Hence, a re-examination of Daedalus seemed an obvious way to go. This would allow a complete re-evaluation of the original assumptions as well as hopefully
improve the design.

Ultimately, the aim would be to improve the Technological Readiness Level for this sort of engine design type. If other teams used the same approach, and say built upon historical projects like Vista, Longshot, TAU or Starwisp it is a personal belief that the credibility of engineering designs for interstellar missions would be vastly improved. The historical link with both Orion and Daedalus also captured the hearts of the Icarus team and made for a strong support base upon which to galvanize both academic and public interest; a necessary condition to inspire people that this design study is worth doing. Although it is also true that after having questioned the original assumptions of Daedalus, the final Icarus design may look very different with technology not envisaged in the 1970s.

Of course, it is also worth pointing out that the Project Icarus Terms of Reference actually stipulate ‘mainly fusion based propulsion’. This allows for the potential for high gain enhancements such as by using Antimatter Catalyzed Fusion techniques. Similarly, the main engine can be supplemented by a secondary engine for part of the mission trajectory, such as by using a nuclear-electric engine.

It is generally the consensus within the interstellar community that the two strongest candidates for interstellar flight and which are a balance between performance and near term technology readiness is arguably solar sails and nuclear pulse propulsion. The large interest today in using solar sails for interstellar missions came about as a result of a publication in 1984 titled ‘World Ships: Concept, Cause, Cost, Constructions, and Colonization”, written by several members of the Daedalus Study Group who had spent many years studying fusion based propulsion. Thus demonstrating that the act of completing an interstellar design study opens up opportunities perhaps not before envisioned.

If designers concentrate on trying to advance these two schemes, solar sailing and nuclear pulse, the prospects for robotic missions to the Kuiper belt, Oort cloud and beyond will become ever more likely. Project Icarus hopes to contribute towards this end objective. It was the vision of Arthur C Clarke that humans should expand out into space as soon as possible, a necessary step for the continued survival and advancement of our species. Project Icarus is aimed at working towards this ultimate goal. So while from time to time we may have to justify to a sceptical public the motivations behind the assumptions of Project Icarus such as the choice of a fusion engine, the design team will remain focussed on achieving our objectives and continue to dream about the challenge of the spaceship.

When people read about The British Interplanetary Society Project Daedalus they usually marvel at the boldness of the idea and the amount of thought that went into the engineering calculations. Indeed, the major objective of Project Daedalus was to carry out a feasibility study for a simple interstellar mission but using only present day technology and with reasonable extrapolation to near future technology. However, it is not immediately apparent why Project Daedalus was undertaken in the first place.

One of the reasons was to investigate the Fermi Paradox first postulated by the Italian Physicist Enrico Fermi in the 1940s. This supposes that there has been plenty of time for intelligent civilizations to interact within our galaxy when one examines the age and number of stars, as well as the distances between them. Yet, the fact that extra-terrestrial intelligence has never been observed leads to a logical paradox where our observations are inconsistent with our theoretical expectation. This original question from Fermi seemed to also reinforce the prevailing paradigm at the time that interstellar travel was impossible.

Project Daedalus was a bold way to examine the Fermi Paradox head on and gave a partial answer – interstellar travel was possible. The basis of this belief was the demonstration of a credible engineering design just at the outset of the space age that could in theory, cross the interstellar distances. In the future scientific advancement would lead to a refined and more efficient design. The absence of alien visitors would therefore require a different explanation because Project Daedalus demonstrated that with current, and near future, technology, interstellar travel was feasible. Therefore, another solution to the absence of extra-terrestrial visitation was necessary. Although Project Daedalus was ostensibly focused on designing an interstellar flyby probe, the underlying motives were to frame discussions about the Fermi paradox.

In the years after Project Daedalus, a member of the Daedalus team Alan Bond plunged himself into researching biology to understand how species evolve from a single celled organism to something as complex as human beings. He argued that historically pure guess work had been used to determine the number of intelligent civilizations in our galaxy. The culmination of his research resulted in the publication of a paper ‘On the improbability of intelligent extraterrestrials‘ in 1982 in the Journal of the British Interplanetary Society. He concluded that organisms with the complexity of human beings may be rare and only occur with a probability below much less than once per galaxy.

This startling conclusion was based upon the development of a biological model assuming an observed exponential growth in the complexity of biological life in the fossil records over time. Bond had addressed the probability of Earth-like planets with Carbon based biology existing in our galaxy. Proteins, the complete set of genes which pass from a parent to an offspring, were seen as the fundamental mechanism of biochemistry on all worlds. The genome would increase in size over time and the establishment of intelligence would require a certain level of intelligence and therefore a minimum size of genome; the more complex an organism then the larger the genome required for its specification. Attainment of an intelligence level like us would take merely a few million years, for species which had a similar genome size.

Bond himself stated in the paper that a lot of assumptions had been made with inaccurately known parameters and that more work needed to be done. He said further that there was clear potential for an order of magnitude variation around the estimates that were derived. His actual numbers suggested that a planet with the development level of the Earth only occurs once in 50,000 galaxies.

He concluded that “whilst we are sufficiently rare to inhibit contact, at least with the Galaxy at its present age, we are not so rare as to defy phenomenological explanation”. The conclusions of this paper are a disappointment for those who believe intelligent life to be prolific. But it is interesting that in the Cosmos television series Carl Sagan also expresses the view that although life may occur purely as a function of chemistry and on most worlds where the environment is suitable, intelligent life in complex beings like us may be rare. When two great thinkers share a similar vision this requires contemplation. The rare intelligence hypothesis paints a very different picture of intelligent life in the universe to that of shows like Star Trek.

As a literature search on the internet shows, there are many potential answers to the Fermi Paradox and it may remain unresolved for some time. Although, advances in observational techniques for looking at distant extra-solar planets may lead us to an answer sooner than we think. One thing is for certain though, the contribution of Project Daedalus to the debate was first rate, demonstrating the possibility of star travel and forcing us to consider other more profound answers. It was no surprise that Alan Bond would also be one of the pioneers in searching for alternative explanations. There is one way we will know for sure, and that it to build something like Daedalus or Icarus in the coming decades, and then go see for ourselves.

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Useful Links

Visit the Project Icarus website

Project Icarus a Starship for the 21st Century

Project Daedalus, a Nuclear Starship

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The potential of nuclear power as a propulsion mechanism that would allow for interstellar flight has been recognized since the first half of the 20^th century. The idea was initially proposed by Stanislaw Ulam at Los Alamos in 1947 and then, in 1958, Ted Taylor initiated Project Orion.

The idea behind Project Orion is to detonate a nuclear charge at some distance from a vehicle. The detonation creates an expanding plasma wave which transfers momentum to the vehicle by hitting a pusher plate. This detonation process is repeated, and the rocket achieves thrust. In 1965, the Test Ban Treaty, which prohibits the detonation of nuclear devices in space, put a stop on the development of the nuclear pulse rocket.

Several years later, Alan Bond of the British Interplanetary Society, believed that the time was right to investigate the feasibility of an interstellar mission. He discussed the idea with members of the Society and Project Daedalus was born.

Project Daedalus began on 10^th January 1973 and the final reports were published 15^th May 1978 taking just over 64 months or over 5 years. Approximately  10,000 man hours were used by 13 core designers and several additional consultants.

In essence, Project Daedalus was a feasibility study for an interstellar mission, using 1970’s capabilities and credible extrapolations for near-future technology. One of the major objectives was to establish whether interstellar flight could be realized within established science and technology.

The conclusion of the report was that Interstellar flight is feasible.

Useful Links

Visit the Project Icarus website

Interstellar Propulsion and the Fermi Paradox

Project Icarus, a Nuclear Starship

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Project Icarus: son of Daedalus – flying closer to another star.

Project Icarus is a theoretical design study with the aim of designing a credible interstellar probe that will serve as a concept design for a potential unmanned mission that could be launched before the end of the 21^st century. Icarus will utilise fusion based engine technology which would accelerate the spacecraft to approximately 10% to 20% the speed of light. The project is a five year design study that began on the 30th September 2009. A large team is already forming, and to date there has already been one conference, and two journal submissions which are currently in the peer review stages.

It might be too early to say that this project will pave the way for the cheapest airline tickets bound for outerspace, but its projected contributions to space exploration should definitely be huge. Project Icarus is a Tau Zero Foundation initiative in collaboration with The British Interplanetary Society. Both organizations serve to promote the vision of manned space exploration and thus  project Icarus has a solid support base and a well developed intellectual resource.Visit the Project Icarus website

Broadly stated, the purpose of Project Icarus is as follows:

1. To design a credible interstellar probe that is a concept design for a potential mission in the coming centuries.
2. To allow a direct technology comparison with Daedalus and provide an assessment of the maturity of fusion based space propulsion for future precursor missions.
3. To generate greater interest in the real term prospects for interstellar precursor missions that are based on credible science.
4. To motivate a new generation of scientists to be interested in designing space missions that go beyond our solar system.

The goal of designing a credible interstellar spacecraft is a huge challenge and thus the research has been divided into 20 modules, and this encompases all of the spacecraft systems and sub-systems. These encompass all aspects of the design of the spacecraft.

The project has been set up in three stages:

• Establish initial design team and complete Terms of Reference by September of Year 1 (2009)
• Fully assemble design team by the end of Year 1 (2009)
• Construct research programme by the beginning of Year 2 and Team Icarus officially begins technical work by the spring of Year 2. (March 2010)

We estimate that, with 20 volunteer designers, Project Icarus will require around 35,000 total man hours which will be spread over a five year research programme culminating in the final design.

For comparison, Project Daedalus began on 10^th January 1973 and the final reports were published 15^th May 1978 taking just over 64 months or over 5 years. The study reports state that around 10,000 man hours were used by 13 core designers and several additional consultants.

The design team for Project Icarus will be split up as follows:

• Core Design Team: The Core Design Team is the main design group that drives the project forward and performs the majority of the work. All are personally known to each other and also manage the project.
• Floating Designers: Floating Designers may not be personally known to the team but have agreed to contribute technically to the project by working on a system or sub-system.
• Consultants: Consultants do not perform the technical work but have a strong an advisory capacity.
• Reviewers: This is mainly made up of members of the Daedalus study group and has the function of providing a constructive technical review of any work produced by the team at various stages.

 More than thirty years has passed since the landmark Daedalus engineering study. Project Icarus will be a complete redesign of the Daedalus systems including a re-examination of some of the original assumptions. An international team is currently assembling to work on this exciting endeavour and bring the human dream of interstellar travel closer to reality.

Official Project Icarus Logo

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Useful Links

Interstellar Propulsion and the Fermi Paradox

Project Daedalus, a Nuclear Starship

Below illustrates the stages of the Icarus project divided into 10 phases. The status of each phase will be indicated by the color of the phase number via the following colouring legend:

Green - On schedule
Red – Behind Schedule
Amber - Ahead of Schedule

For example “Phase 1” would be on schedule because it is coloured green.

The status of the project will be updated giving anyone visiting our site an indication of the progress of Project Icarus which will span the next 5 years.

Phase 1
Description: Team assembly & definition of terms of reference, by end of 2009.
Deliverable: Internal publication of Physics Requirements Document & team assembly.

Phase 2
Description: Construction of work programme, up to spring 2010.
Deliverable: Internal publication of Project Programme Document & allocation of work programme, Stage Gate 1.

Phase 3
Description: Work programme conceptual design, by spring 2011.
Deliverable: External publication of concept design options, Stage Gate 2.

Phase 4
Description: Work programme preliminary design, by end of 2011.
Deliverable: Internal publication of preliminary design options.

Phase 5
Description: Preliminary design review, by early 2012.
Deliverable: Pass preliminary design review & complete actions as appropriate, Stage Gate 3.

Phase 6
Description: Work programme, down select to detailed design options, by end of 2012.
Deliverable: Down select to Baseline Model & internal publication of System Requirements Document.

Phase 7
Description: Work programme, system integration, by summer 2013.
Deliverable: Produce Integrated Baseline Model & internal publication of Sub-System Requirements Document.

Phase 8
Description: Detailed design review, by end of summer 2013.
Deliverable: Pass detailed design review and complete actions as appropriate, Stage Gate 4.

Phase 9
Description: Certification of theoretical design solution, by end of 2013.
Deliverable: Internal publication of Icarus Certification Document, Stage Gate 5.

Phase 10
Description: Publication of final design solution, submit to JBIS early 2014.
Deliverable: Publication of executive summary reports represents the key deliverable for Project Icarus.

Welcome to the Icarus blog. On this page, members of the Icarus team will post their thoughts and ideas while being able to interact with visitors to the site.

To contact the Icarus team write to: info@icarusinterstellar.org