July 17, 2012
H/T to Discovery Space News (Ian O'Neill) Using Lasers and Antimatter to Trek to the Stars.
While interstellar mission have been explored in the literature, one mission architecture has not received much attention, namely the interstellar rendezvous and return mission that could be accomplished on timescales comparable with a working scientist’s career. Such a mission would involve an initial boost phase followed by a coasting phase to the target system. Next would be the deceleration and rendezvous phase, which would be followed by a period of scientific data gathering. Finally, there would be a second boost phase, aimed at returning the spacecraft back to the solar system, and subsequent coasting and deceleration phases upon return to our solar system. Such a mission would represent a precursor to a future manned interstellar mission; which in principle could safely return any astronauts back to Earth.
In this paper a novel architecture is proposed that would allow for an unmanned interstellar rendezvous and return mission. The approach utilized for the Vacuum to Antimatter-Rocket Interstellar Explorer System (VARIES) would lead to system components and mission approaches that could be utilized for autonomous operation of other deep-space probes. Engineering solutions for such a mission will have a significant impact on future exploration and sample return missions for the outer planets. This paper introduces the general concept, with a mostly qualitative analysis. However, a full research program is introduced, and as this program progresses, more quantitative papers will be released.
VARIES Mk 1 design based on discussions of critical systems with project artist. Solar panels extract energy from the target star and power either quantum batteries or ultra powerful capacitors. These, in turn, power a laser which generates Schwinger antiparticle pairs from the vacuum, which are then stored for propulsion. (Adrian Mann)
This paper does not intend to be a blueprint to the VARIES concept, it is important to scope the realism of the concept. The goal of this research program is to construct a spacecraft architecture with the unique capability to create antiproton fuel from the vacuum of space itself, utilizing the phenomenon of Schwinger pair creation using intense electromagnetic fields. The mission architecture would be optimized for an interstellar rendezvous and return mission, which would lay the foundation for future manned missions by demonstrating the ability to return a spacecraft safely to our solar system after having visited a distant target solar system.
Recent experimental advances have raised hope that lasers may soon achieve field intensities on the order of the critical field intensity.
Recent research indicates that the Schwinger pair creation mechanism can be catalysed by introducing a strong amplification mechanism for pair production by a tunnel barrier suppression, while fully preserving the characteristics of the mechanism. This dynamically assisted mechanism suggests the possibility of significantly enhancing the pair creation rate.
There is confidence within the scientific community that, within the next decade, laser field intensities will reach the critical field intensity necessary for pair creation from the vacuum.
Magnetic Nozel
Pions formed from the annihilation of the protons and antiprotons will have to be directed for thrust, and so propulsion systems that need to be studied will include magnetic nozzles, which will, essentially, be high temperature superconducting magnets. The magnetic nozzle consists of a monoloop superconductor coil at a temperature of 100K. Previous modelling using this geometry has been performed for the VISTA study. Monte-Carlo modelling of the protonantiproton reaction has been used to determine the effective Isp of an antimatter rocket. These studies indicate that there is an imperfect reflection of the charged pions, with some particle travelling upstream of the nozzle due to the limited capabilities of the magnet to reflect the ions downstream for thrust. Clearly, perfection of the reflective properties of the magnet will be of value for increased specific impulse, and this should be investigated further.
The solar panel area required to generate 10 kg of antiprotons, over a period of 1 year, at a distance of 1 AU from the target star, with an energy conversion efficiency of only 0.01 is 2,088 square kilometers. This corresponds to a panel of side 45.7 km.
It would seem that getting closer than 1AU would be worthwhile.
There is a solar probe mission that is looking to get closer to the sun and get 250 times more sunlight per area. This would mean 16 times less size in height and width. About 3 km on a side panels.
Antimatter Storage
Howe and Smith, as part of a NASA Phase I study, investigated two possible high density antimatter storage concepts: first, the possible reduction of the antimatter annihilation at the walls of the antiprotons stored as non-neutral plasmas so as to increase the storage capacity, and second, storing antihydrogen as a neutral gas to achieve higher storage densities. They conclude that “Both of these concepts could enable systems with ultrahigh energy density to be developed. Proof of concept experiments have been designed and may be completed within the next few years.”
More recently, breakthroughs within the ALPHA project at CERN have demonstrated the confinement of antihydrogen for 1000 seconds, further adding to the feasibility of antimatter storage
Areas of Further Research
• The Schwinger pair creation mechanism
• Catalyzation of the pair mechanism for enhanced antimatter production rates
• The utilization of solar energy in the target solar system for pair creation
• System requirements for generating sufficiently powerful electric fields to initiate the Schwinger mechanism, and the associated mass of the driver system
• Selection and optimization of a high density antimatter storage system
• The evaluation of energy storage options, including quantum batteries
• Investigation into the possible utility of inflatable solar panel structures
• Investigation into the possible utility of the Oberth twoburn manoeuvre to increase Δv both for escape from our solar system, and the target solar system
• Communications
• Thermal load balancing
• Shielding from interstellar dust collisions
• Integration of an antimatter primary propulsion system
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