Icarus: Revisiting the Daedalus Starship

by Paul Gilster on March 19, 2009

by Kelvin Long

Project Daedalus was the first thoroughly detailed study of an interstellar vehicle, producing a report that has become legendary among interstellar researchers. But Daedalus wasn’t intended to be an end in itself. Tau Zero practitioner Kelvin Long here offers news of Project Icarus, a follow-up that will re-examine Daedalus in light of current technologies. A scientist in the plasma physics industry and an aerospace engineer, Long is assembling the team that will begin this work in 2010, following a ‘Daedalus After 30 Years’ symposium scheduled for September at the headquarters of the British Interplanetary Society. Can we improve Daedalus’ propulsion systems, change its targets, modify its shielding? Numerous theoretical studies await.

During the period 1973-1978 members of the British Interplanetary Society undertook a theoretical study of a flyby mission to Barnard’s star, some 5.9 light years away. This was Project Daedalus, which remains the most detailed study of an interstellar probe ever attempted. The 54,000 ton two-stage vehicle was to be powered by inertial confinement fusion using electron beams to compress deuterium/helium-3 fusion capsules to ignition.

Daedalus was to have obtained an eventual cruise velocity of 36,000 km/s or 12% of light speed from over 700 kN of thrust, burning at a specific impulse of 1 million seconds. Travel time to flyby at destination would be approximately 50 years.

Daedalus had three stated guidelines:

  • The spacecraft must use current or near-future technology.
  • The spacecraft must reach its destination within a human lifetime.
  • The spacecraft must be designed to allow for a variety of target stars.

Announcing Project Icarus

Project Icarus: Son of Daedalus – flying closer to another star. This is the full name of the new study, a Tau Zero Foundation initiative in collaboration with the British Interplanetary Society (BIS). Over three decades have passed since the Daedalus work, making this a good time to revisit the design study in light of scientific and technological advancements.

The purpose of Project Icarus is as follows:

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

Certain reference points follow on from the original Daedalus study, modified to reflect changes of time and circumstance. Thus the spacecraft design must use current or near-future technology so that it could be credibly launched by 2050. It must be designed to reach its destination as quickly as possible, in a time-frame not exceeding sixty years but, hopefully, much sooner. The propulsion system must be mainly fusion-based. Assuming realistic maximum cruise speeds of 0.3 c and a sixty year flight duration, this places approximately forty-eight stars within an 18 light year distance within range of Icarus.

Genesis of a New Starship Study

In the introduction to the Daedalus study report Alan Bond states that:

“…it is hoped that these ‘cunningly wrought’ designs of Daedalus will be tested by modern day equivalents of Icarus, who will hopefully survive to suggest better methods and techniques which will work where those of Daedalus may fail, and that the results of this study will bring the day when mankind will reach out to the stars a step nearer.”

So in essence, the naming of the successor project as Icarus was suggested by the original study group.

Daedalus and Icarus were characters from ancient Greek mythology. In an attempt to escape the labyrinthine prison of King Minos, Icarus’ father Daedalus fashioned a pair of wings made of feathers and wax for both himself and his son. But soaring joyfully through the sky, Icarus flew too close to the sun, melting the wax on his wings. He fell into the sea and died after having ‘touched’ the sky. Project Icarus aims to ‘touch’ the stars and escape from the bounds of mother Earth.

Toward an Evolving Design

An assessment of the many dozens of propulsion concepts for interstellar flight made it clear that one way to advance the prospects for interstellar travel would be to focus on a specific design proposal. This way, a concept design could be derived, iterated and improved. Over time, the concept would be worked upon by future generations and could ultimately lead to a design blueprint for an interstellar probe. As the Daedalus study was performed three decades ago, it seemed appropriate to start by re-designing the Daedalus probe with updated scientific knowledge.

Thus the genesis of Project Icarus. It is hoped that other teams around the world will eventually be assembled, working on specific propulsion proposals that have been investigated in the past, such as Starwisp, VISTA, AIMStar or one of the many others. In this way, the technological maturity of different propulsion schemes can be improved over time, drawing on a common background of study rather than diverse and uncoordinated research efforts.

Needless to say, Centauri Dreams will provide regular updates on the progress of the Icarus design team, which will also be developing its own Web site in conjunction with the September symposium.

{ 65 comments }

Administrator March 26, 2009 at 15:18

Ron, I don’t remember how deeply Lesh and Cesarone went into these calculations, but if the material isn’t in their text, I’m sure they point to it in the footnotes. Lesh proposes a 20-watt laser system with a 3-meter telescope only slightly larger than the Hubble Space Telescope as the transmitting aperture. Once in Alpha Centauri space, the probe would lock onto our Sun and use it as a pointing reference, its signals received by a 10-meter telescope in Earth orbit to avoid any absorption of the signal by the atmosphere. The Earth receiver would use optical filters to remove most of the incidental light from the Alpha Centauri system.

He said this in our interview: “This is a system that is feasible right now. If we had a propulsion system that could get us to Alpha Centauri in ten years, or twenty, I am saying that the communications system is not a problem.”

Of course, propulsion still is, but we know that…

Howard T. March 27, 2009 at 7:44

I was thinking of accelerating away with a solar sail and just furling it up, if made necessary by inertial moment, turning around and unfurling it to ecelerate. It wouldn’t be enough to let it get into orbit I imagine.. and it would take longer. But the builders would still be alive… This would have to be an international effort and humanity will endure. Slower might be better, in terms of being able to improve the onboard control program.

Collision avoidance would get more and more difficult as speed builds up, but on-board radar would seem to be a given. But, probably at some point, you’d have to trust to luck. Too much course deflection and you will miss the endpoint.

The administrator said, more than once, that the target would be Alpha Centauri. Is that a given now? I would think that decision wouldn’t be made until the James Web or following space telescope has interferometered its little heart out?

Administrator March 27, 2009 at 8:14

Howard T. wrote:

The administrator said, more than once, that the target would be Alpha Centauri. Is that a given now? I would think that decision wouldn’t be made until the James Web or following space telescope has interferometered its little heart out?

Feel free to call me Paul. Re targets, I’m quite interested in Alpha Centauri but it’s only one of numerous possibilities within the range being factored into the Icarus design. An even bigger question is whether a hugely expensive flyby probe could be built before our observational technologies have grown past it; i.e., to the point where we can get most of the information we need from here rather than there. But that’s another subject entirely!

Using a sail for initial acceleration and later deceleration is indeed a workable idea, as Robert Forward showed in his more advanced lightsail designs. But remember that Icarus is specifically set up by its design team to be fusion-based, as the descendant of the original Daedalus design. I’d love to see a laser or microwave-sail team go to work on a similar project.

Howard T. March 27, 2009 at 9:29

The mission statement says ‘mainly’ fusion based. Doesn’t that leave open whatever secondary stages could most benefit the mission objectives? A second stage sort of thing… but maybe with or without dropping the initial launchers and fusion ion propulsion. Surely observations made over time would be vastly more valuable than what could be obtained while flashing by at .12c?

Surely no radar returns or other remote return would even be possible? Just passive observation seems pretty limiting.

The Harwit article is pretty curt.. but it saysnit’s doable. I emailed him and asked him if he would like to weigh in here.

Ronald March 27, 2009 at 11:20

With ref. to Goldstein Hovercraft’s remarks about expensive flyby missions versus telescopes, Paul’s very appropriate statement of March 27, 8:14 about the same (“An even bigger question is whether a hugely expensive flyby probe could be built before our observational technologies have grown past it; i.e., to the point where we can get most of the information we need from here rather than there”) and also Paul’s sobering equation of March 26th, 8:41 (A next generation ion engine would need more than 500 propellant tanks the size of supertankers (…). If you want to decelerate the same payload (…) would need to be supplemented by another three hundred million supertankers…);

Both the physics and economics convince me that a mere flyby mission to another stellar/planetary system would never be feasible, even if technically possible: nearly anything that such a mighty expensive and very short-duration flyby could achieve, can also be achieved with far (FAR) smaller investment and much (MUCH) smaller risk using telescopes.
A flyby mission would be a very expensive one-time and everything-or-nothing exercise.

Even in the foreseeable future we can expect to learn a great deal about relatively nearby terrestrial exoplanets by means of both ground-based extremely large telescopes (ELT, OWL etc.) and space-based interferometry missions (TFP, Darwin, etc.). And even the detection of planets in the Andromeda galaxy by means of microlensing/gravitational lensing is not outside our immediate future possibilities (e.g. see THE POSSIBILITY OF DETECTING PLANETS IN THE ANDROMEDA GALAXY, by Chung & Kim).

And of course a telescope in the sun’s gravitational focal point (such as FOCAL) would enhance our observational possibilities spectacularly (some 10 million times). Although I expect such an instrument would rather be used in the first place to image really distant objects like neighboring galaxies such as Andromeda, it could also be used for imaging planets in nearby systems.

I would maybe make an exception for a laser-driven propulsion system as Paul also mentions in his post of March 26th (“The mass ratio problem is why so many of us are interested in beamed propulsion concepts, leaving the propellant to be supplied from the Solar System via laser”), that can spit out a large number of (very) small low-cost probes.

Otherwise we’ll have to wait for a breakthrough in physics and particularly anti-gravity along the lines of Heim, Tajmar, Chiao (see other recent thread), I am afraid.

Administrator March 27, 2009 at 14:13

I tend to agree with that, Ronald, although I do see great value in working through a range of scenarios for mission design as we tune up technologies that could may them flyable. One of them may well fill a particular niche one day and help us with, say, a fast mission to the Kuiper Belt or the Oort Cloud. And who knows where we may wind up as we keep juggling the possibilities.

The question of data return on a .12 c flyby through a planetary system is also valid. I’m sure we’d learn a lot on approach and flyby but justifying the cost of that when weighed against benefits is quite iffy.

Adam March 27, 2009 at 21:18

Hi Paul

If “Icarus” is meant to be fusion propelled could it still be deccelerated by electromagnetic drag? And if the accelerator beam is powered by fusion would that count?

Administrator March 28, 2009 at 10:12

Good questions, Adam! And I don’t have the answer — I suppose it will come down to how much latitude the design team wants to build into the project. They’ll have a lot to consider at that first meeting in September.

Howard T. March 29, 2009 at 14:53

Given the distance to the sun’s gravitational lens points (550 au), it’s going to be costly, lengthy and difficult to get even one telescope there. And a communication lag time of 3.18 days, more or less, will make reliable data return difficult, though doable. But a separate mission to study each star may be beyond our budget. Some orbital mechanic genius maybe will tell me how long it would take to get a craft there? With ion propulsion?

I’m not usually a pessimist, but I don’t think this is feasible. Nor do I think we can push the limits of what telescopes much further than the JWST. No…. we have to go there and take a look closeup. We owe it to our species’ great thinkers to do what they have imagined for us. RAH would expect no less.

So maybe the answer is to take an asteroid there… I can’t recall who proposed that. But it has the advantage of creating both a spaceship and an ark to give the species a chance of survival in case we take an asteroid on the nose.

Howard T. May 7, 2009 at 9:54

Paul… I drpped by to see if there were any new submissions. Unfortunately, the later letters seem to black on grey. My little blackberry can’t read this at all… not enough contrast.

I finally got a copy of your book. It’s fascinating! I also got a copy of “Interstellar Travel and Multigenerational Spaceships”. When I get through these, I’ll try for Matloff’s. Something to lok forward to until Terry Brooks next book.

Many years ago, I read a story about an interstellar ship being hollowed out of an asteroid. The theory being, we wouldn’t need to lift it off earth and it could cannibalize it’s own mass for reaction matter. On arrival, it would be a small fraction of its original size, but for the next trip, it just attached itself to a local asteroid and blasted off.

Some design problems would totally disappear…. talk about shielding! no minor collisions to worry about. You wouldn’t have to worry about space pirates either.. just lock yourself in the engine room for a few years until the navy arrives. (I’m adding a few wrinkles… In truth I remember only the bare details of the book.)

Might this be an idea whose time has come? If we change our mind about going, we could just use it as a space colony. In addition, you wouldn’t have to worry if your destination proved too to not be inhabitable. Sort of an interstellar Winnebago. I suppose this would be beyond the design parameters, but what the heck… go first class.

Did you note Buzz Aldrin’s recent comments that Mars’ astronauts should plan on staying? Or coming home maybe only for retirement. Heinlein would have loved him….

Administrator May 7, 2009 at 10:23

Howard, I think I see the problem. The new software here should be showing you any comments I make to a post with black text on a light blue field, while all other comments should be standard black on white. Maybe the Blackberry is supplying too gray a color instead of the light blue, accounting for the reading issue. Sorry about this, and if I can figure any way around it, I’ll let you know. The comments should come across OK on a regular laptop or desktop PC.

Yes, I agree about Buzz’s comments. Heinlein would have loved that attitude!

Thanks for your kind comments on my book, and yes, be sure to head for Matloff’s Starflight Handbook, which you’ll find packed with interesting ideas. In particular, his treatment of the propellant problem with traditional rocketry is an eye-opener, and he and Eugene Mallove go through all the interesting options, from lightsails to ramjets. I don’t recall his getting into the asteroid idea, but hollowing out a huge rock certainly does solve many of the worst problems of interstellar flight.

B Tunstall September 21, 2009 at 18:05

With respect to Icarus why does it need to be a single indivisible craft?

Accelerate the “main unit” to a reasonable speed then seperate off sub-units that are more maneuverable/lighter as flypast systems. The remainding main unit then has a *possibility* of being able to react based upon preliminary findings. Slowing/accelerating the rest of the main unit via sails would mean that no addition fuel is required.

I accept that this complicates the design but does enhance the chances of the majority of the craft establishing results of impoirtance. If the separation phase is timed correctly then could not sail deceleration make it able to enter orbit?

Peter October 26, 2009 at 23:54

It’s a wonderful age that we live in- people have the raw materials to do anything someone who formerly needed an assload of credentials could only do- use the latest ideas from the physics community to make great leaps of progress…

Let’s face it- before the internet, progressive physics was almost exclusively the domain of the university establishment Phds. Now that all those papers are available to anyone for free, I expect to see major upheavals in the physics community.

I’m not taking about the latest paper either- I’m talking about what people can do with that knowledge.

Brian May 5, 2010 at 6:12

Regarding telescope technology: While I’m sure it will vastly improve, I can easily assert there will easily be some things even in our own solar system that a telescope will not penetrate in a hundred years. Even a flyby probe of Titan can’t penetrate its haze sitting right next to it. We can’t even penetrate the thinnest surface of Earth’s oceans from above the sea (as opposed to inside it). All these years haven’t improved either of these one bit – penetrating telescopes are a matter of glacial improvement and even assuming exponential improvement it just isn’t going to happen.

The point is that physical presence is necessary for exploring even our own solar system or our own planet. People wrote off Titan of all places looking at it from telescopes and direct flyby probes for decades. Here we’re discussing another solar system in the time frame of a century, which is a far more demanding task.

The fact is, telescope technology improvements only apply to certain types of observations. If you can’t even look into Titan sitting right next to it, just try to peer inside using a telescope. It’s going to be a while.

Steven November 10, 2010 at 20:14

Why not just put a heavy probe in a mass driver mounted on the moon? Seems like it’d be a bit cheaper, and you could get better velocities. The technology is current, the idea would be much less expensive, and you could reach velocities to reach the nearby stars in much less time.

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