by Richard Obousy

As project leader for Project Icarus, the ambitious successor to the British Interplanetary Society’s Project Daedalus starship design, Richard Obousy is deeply engaged with the advanced propulsion community. Here he gives us a report on the recent Advanced Space Propulsion Workshop, which he attended in November. It was a sizable gathering, but Richard focuses here on work of particular relevance to Project Icarus and the Tau Zero Foundation, the twin backers of Icarus.

Recently, several members of the Project Icarus team attended the 2010 Advanced Space Propulsion Workshop (ASPW) at the University of Colorado in Colorado Springs. The event ran from from Monday, November 15 through Wednesday, November 17, with over sixty presentations given by a number of researchers. Project Icarus attendees included James French, Rob Adams, Robert Freeland, Andreas Tziolas and myself.

The ASPW is focused on low Technology Readiness Level (TRL) concepts ranging from TRL 1 to 3. A TRL is a measure of the maturity of an evolving technology, with TRL 1 representing the very lowest level of maturity, with only the basic physical principles of an idea demonstrated. At the other end of the spectrum, TRL 9 represents a system that is, for the most part, tested and operational. A detailed breakdown of the TRL levels can be found here.

A TRL 1 to 3 conference typically brings together a good mix of pioneering thinkers who are willing to think outside of the box and explore untested ideas and concepts. Most of the attendees were either NASA scientists, worked at JPL, or were actively affiliated with a university, so the science that was presented was all very plausible and grounded in ideas that could be brought into fruition within a few decades (earlier in some cases), given a sufficient investment of time and funding.

Image: The conference looked out to Pike’s Peak, a 14, 115 ft (4.3 km) elevation mountain. Credit for all images: Richard Obousy.

A number of talks caught our attention due to their relevance to the Icarus Project. One such talk was delivered by John Slough, who gave an intruguing presentation on his research at the University of Washington on Inductively Driven Liner Compression of Fusion Plasmoids. His was the only team at the conference working on pulse propulsion concepts.

The basic concept involves pulsing fusion fuel plasma at high rates into a reaction chamber where it would undergo fusion via use of metal liners to accomplish compression of a magnetized plasmoid. Although remarkable, the only purpose of the fusion would be to drive the next round of plasmoid firing. Propulsion would be achieved through momentum transfer occurring between the electromagnetic gun and the accelerating plasmoid. In other words, all the fusion gain would be put back into driving the next cycle. This differs markedly from the idea behind Daedalus, where a large fraction of the exploding fusion material itself transfers the momentum.

Image: John Slough(University of Washington) speaking on fusion plasmoids.

Rob Adams (Project Icarus) gave a fascinating talk on a conceptual design of a z-pinch fusion propulsion. The results of a detailed study that he had been involved in were presented. These results included the modeling of the z-pinch fusion rocket, the propulsion characteristics, an evaluation of a magnetic nozzle, mission analysis and overall vehicle design.

Image: Rob Adams (Project Icarus) explaining z-pinch fusion propulsion.

Andreas Tziolas (Project Icarus) gave a thoughtful overview of candidate technologies for interstellar exploration and then went on to discuss various aspects of Project Icarus, including ideas that the team has been discussing including vIcarus, satIcarus and others. Andreas received a number of questions from the audience, including one from Sonny White who suggested that the Icarus team put some effort into possible spin-offs that could be realized within two or three decades.

Image: Andreas Tziolas giving his talk on interstellar enabling technologies.

I had the pleasure of presenting a talk on Day 1 that introduced Project Icarus. I spent some time discussing our overall objectives and who makes up our team. I also talked about the original Daedalus propulsion systems and described the essential features, including the cryogenic storage, Deuterium – Helium3 pellet design, injector nozzles, electron beams and the reaction chamber and magnetic nozzles.

Image: Richard Obousy talking about Project Icarus, and the Daedalus propulsion systems.

Day 1 ended in the local student union building with dinner and drinks, which the team enjoyed thoroughly.

The plenary session of Day 2 was opened by Les Johnson, Deputy Manager for the Advanced Concepts Office at NASA MSFC in Huntsville. Les described the limitations of chemical rocket propulsion and illustrated an overall technology roadmap that could provide NASA with the pathways required to meet the space agencies exploration goals for the 21st century. The technologies Les described would enable more effective exploration of our Solar System.

Image: Les Johnson speaking on Day 2 of ASPW 2010.

The renowned Robert Frisbee gave a talk titled ‘To The Stars, One Way or Another,’ which described the details of several studies he had performed while working at JPL over the years. These studies were aimed at identifying propulsion technology requirements for interstellar missions. He explained to us that these studies were made intentionally difficult, and would involve a rendezvous mission as well as a top speed of 0.5c. He also briefly reflected on some breakthrough propulsion ideas, including wormholes and warp drives, and also an analysis of the negative energy requirements for these schemes. This was the first time I have seen Robert speak, and I want to emphasize that he was a thoroughly entertaining and enjoyable presenter. I was surprised at how animated and enthusiastic he was during his presentation, and enjoyed the many clever ‘wise-cracks’ he managed to throw into his talk.

Image: Robert Frisbee giving his talk “To the Stars, One Way or Another.”

Day 3 included a number of fascinating talks, including a talk by David Kirtley (MSNW LLC) who spoke on the concept of ‘Macron Propulsion’, an idea that involves firing small fuel pellets in front of a spacecraft which would then be utilized by that craft for fuel. This ingenious, yet complex approach is attractive, since it overcomes the Rocket Equation as the fuel is not stored onboard the craft. The talk had very interesting parallels to the Daedalus electromagnetic pellet launcher. MSNW has built and is currently testing a 20 Tesla launcher and also a prototype pulsed power bank.

James French (Project Icarus), a veteran rocket scientist who worked on the Saturn V engines, gave a talk on Gas Core Nuclear Rockets. He first gave an overview of the solid and liquid core rockets, and then discussed some of the challenges associated with heat transfer for the working fluid, cooling of the solid parts of the engine and also the problem of how to start and stop a gas-core rocket.

James illustrated the potential use of the Gas Core rocket for Icarus by illustrating a calculation that revealed a potential course correction for a probe released from the main Icarus ‘mother-ship’ traveling at a reasonable fraction of c. The conclusion at which James arrived was that there is potential utility for gas core rockets within Project Icarus.

Image: James French (Project Icarus) talking on Gas Core Nuclear Rockets.

Rob Adams (Project Icarus) gave his second talk of the conference, and explained the Oberth two-burn maneuver. While it was the most amusing talk of the conference (Rob cracks a lot of jokes), it also detailed Rob’s process of rediscovering the Oberth maneuver. This relatively unknown effect is often confused with the gravitational slingshot, but differs markedly in its application. When a spacecraft executes the Oberth maneuver, it is able to obtain far more useful energy for greater delta v than a stationary rocket. Rob believes this maneuver is generally unknown, even among experts, and emphasized its scientific value. He also explained that the maneuver could be used effectively for future missions to obtain higher delta v.

Robert Frisbee gave the final talk of the day, which was largely to encourage all present to ‘think big’, and to explore low TRL technologies so that breakthroughs in understanding can be accomplished. I particularly enjoyed one of Robert’s quotes where he explained that “It’s all science fiction until somebody goes out and does it.” Robert received a standing ovation at the end of his presentation, which was a fitting end to the conference.

Image: From left to right: Andreas Tziolas, Rob Adams, Richard Obousy, Jerry Winchester, Robert Freeland, Jim French.