DOW-UAP-D126, AAWSAP DIRD, Advanced Nuclear Propulsion for Manned Deep Space Missions, March 2010

This document is a Defense Intelligence Reference Document (DIRD), a technical reference format used by the Defense Intelligence Agency (DIA) to capture baseline knowledge on a specific topic for later analytic use. DIRDs are best understood as reference and synthesis products rather than as original research. It is one of 38 DIRDs produced under the Advanced Aerospace Weapon System Applications Program (AAWSAP) between 2009 and 2011. Because AAWSAP’s scope permitted a broad range of supporting topics, not every DIRD in the series directly concerns aerospace systems or future threat assessment. The following summary reflects the DIRD’s scope and framing at the time of writing and should not be read as implying current validation of the concepts discussed. This DIRD examines advanced nuclear propulsion for crewed deep-space travel and argues that human missions beyond the Moon would require propulsion systems with both very high thrust and very high specific impulse, which the author contends are difficult to achieve with conventional chemical, nuclear-thermal, and nuclear-electric systems. The report focuses on concepts derived from Project Orion, the discontinued General Atomics nuclear pulse propulsion study sponsored first by ARPA and later by the U.S. Air Force between 1958 and 1965, in which a spacecraft would be driven by repeated nuclear explosions. In this case, the DIRD emphasizes small non-fission-triggered fusion explosions using deuterium, magnetic mirrors, and other unconventional ignition concepts intended to avoid the inefficiencies associated with small fission devices. It presents these ideas as a possible pathway to crewed missions across the solar system, while also linking them to broader visions of long-range human expansion into space. The document is exploratory in character and depends on several unproven ignition methods, enabling technologies, and engineering assumptions. Overall, it is a theoretical examination of fusion-based pulse propulsion concepts rather than as a documentary account of a technology nearing practical realization.

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Defense
Intelligence
Reference
Document
Acquisition Threat Support
11 March 2010
!COD: 1 December 2009
DIA-08-1003-007
Advanced Nuclear Propulsion
for Manned Deep Space
Missions
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Advanced Nuclear Propulsion for Manned Deep Space
Missions
Prepared by:
Acquisition Support Division (DW0-3)
Defense Warning Office
Directorate for Analysis
Defense Intelligence Agency
Author:
AAP Person 72
Administrative Note
COPYRIGHT WARNING: Further dissemination of the photographs in this publication is not authorized.
This product is one in a series of advanced technology reports produced in FY 2009
under the Defense Intelligence Agency, Defense Warning Office's Advanced Aerospace
Weapon System Applications (AAWSA). Program. Comments or questions pertaining to
l
this document should be addressed tolAAP Person 1 AAWSA Program
Manager, Defense Intelligence Agency, ATTN: CLAR/DWO-3, Bldg 6000, Washington,
DC 20340-5100.
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Contents
Preface....................................................................................................................v
Introduction ........................................................................................................... 1
Deuterium, Argon Ion Lasers, and Kev Superexplosives ........................................ 1
Magnetic Insulation and Inductive Charging .......................................................... 3
Magnetic Insulation ........................................................................................... 3
Inductive Charging.................................................................................................................................... 4
Deuterium as the Preferred Nuclear Rocket Fuel.................................................... 5
Magnetic Entrapment of the Charged Fusion Products and the Stopping of the
Proton Beam in Dense Deuterium .......................................................................... 6
Solution in Between Two Extremes ...................................................................... 10
The Nonfission Ignition of Small Deuterium Nuclear Explosives .......................... 13
Delivery of a Gev Proton Beam Onto the Deuterium Fusion Explosive .................. 15
Lifting of Large Payloads Into Earth Orbit ............................................................ 16
Neutron Entrapment in an Autocatalytic Thermonuclear Detonation Wave - a
Means to Increase the Specific Impulse and to Solve the Large Radiator Problem18
Testing the Deuterium Microdetonation Concept.................................................. 20
Conclusion............................................................................................................ 25
Appendix: Conjectured Metastable Superexplosives Formed Under High Pressure
for Thermonuclear Ignition .................................................................................. 26
Bombardment of a Solid Target With an Intense Relativistic Electron or Ion
Beam................................................................................................................ 28
Hypervelocity Impact ....................................................................................... 28
Bombardment of a Solid Target With Beams or By Hypervelocity Impact,
Followed By a Convergent Shock Wave ............................................................ 28
References ........................................................................................................... 30
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Figures
Figure 1. Ignition With 107-Ampere GeV Proton Beam ......................................... 11
Figure 2. Pure Deuterium Fusion Explosion Ignited With an Intense Ion Beam ... 14
Figure 3. Screening of the Spacecraft................................................................... 14
Figure 4. Superconducting "Atomic" Spaceship.................................................... 15
Figure 5. Argon Ion Laser Igniter......................................................................... 17
Figure 6. Autocatalytic Thermonuclear Detonation Using a Soft X-ray ................. 18
Figure 7. Ordinary Marx Generator....................................................................... 21
Figure 8. Super Marx Generator ........................................................................... 21
Figure 9. Artist's Conception of a 1.5-km-Long Super Marx Generator ................. 21
Figure 10. Detail View of a Section of the Super Marx Generator ......................... 22
Figure 11. Injection of GeV - 10 MA Proton Beam ................................................ 22
Figure 12. Showing a Few Elements of the Super Marx Generator ....................... 22
Figure 13. The Superconducting Toroidal Capacitor and Its Discharge Onto the
Target.................................................................................................. 24
Figure 14. Explosives ........................................................................................... 26
Figure 15. With Increasing Pressure, Electron-Bridges are Formed Between
Shells Inside Shells Melting Into Common Shells ................................ 26
Figure 16. p-d, Pressure....................................................................................... 29
Figure 17. Inertial Confinement Fast-Ignition Configuration................................ 30
Tables
Table 1. The Charged Fusion Products of a Detonation in Deuterium: Their
Energy and Velocity .................................................................................. 5
Table 2. Critical Ignition Currents for Thermonuclear Reactions ............................ 8
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Advanced Nuclear Propulsion for Manned Deep Space
Missions
Preface
My interest in space flight dates to when I was about 10 years old and
received as a birthday gift a popular book about the feasibility of space flight.
From it I learned for the first time about Oberth and Goddard and of the
possibility of reaching the Moon with a multistage rocket. This occurred at the
same time that Hahn and Strassmann announced the discovery of nuclear
fission, with the possibility of an atomic bomb by a fission chain reaction.
Having been born in Germany in 1929, I received my Ph.D. in physics under
Heisenberg in 1955. Inspired by the 15-megaton hydrogen bomb test
conducted by the United States in 1952, I have been deeply interested in the
nonfission ignition of thermonuclear reactions by inertial confinement since
1954. At the time all fusion research in the United States was still classified,
but I had quite independently discovered the basic principles of inertial
confinement, the Guderley convergent shock wave, and the Rayleigh
imploding shell solutions. In 1956 I presented my findings at a meeting
organized by Von Weizsacker at the Max Planck Institute in Goettingen. The
abstracts of this meeting reside today in the University of Stuttgart library.
In 1958 I had delivered a paper at the 2nd United Nations Conference on the
Peaceful Use of Atomic Energy on Nerva-type nuclear rocket reactors. The
paper turned out to be of some importance as I was invited by the U.S.
government to come to the United States under "Operation Paperclip." In San
Diego I met Ted Taylor and Freeman Dyson, who were working on the famous
"Orion" nuclear bomb propulsion concept. This concept is generally credited to
Stanislaw Ulam, but I know from conversations I had with Heisenberg that a
similar idea had been presented to Heisenberg by Wernher von Braun in Berlin
in or around 1942. Because of my idea to use the Guderley convergent shock
wave solution for thermonuclear ignition, Ted Taylor and Freeman Dyson were
interested in my joining their group. But because at that time this work was
classified and I was not yet a U.S. citizen, this was not possible.
In 1967 I saw a new possibility for the nonfission ignition of thermonuclear
microexplosions by intense relativistic electron and ion beams, driven by a
high-voltage Marx generator. This ignition concept could be used not only to
control the release of energy by nuclear fusion, but also to propel a spacecraft,
replacing the pusher plate of the Orion concept with a magnetic mirror,
reflecting the plasma-fireball of the thermonuclear microexplosion (Reference
1, 2). This idea was adopted by the British Interplanetary Society in its 1978
Project Daedalus starship study, replacing a neutron-rich deuterium-tritium
(OT) thermonuclear explosive with a neutron-poor deuterium-helium3 (DHe3)
explosive (Reference 3). Unlike the OT reaction, in which 80 percent of the
released energy goes into neutrons, most of the energy in the D-He3 reaction
goes into alpha particles, which can be deflected by a magnetic mirror. But
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because He3 is not abundantly available everywhere, it was proposed to
"mine" it from Jupiter's atmosphere.
Studies have been conducted on spacecraft propulsion with the matter­
antimatter annihilation reaction, however, it is an enormous technical
challenge to produce antimatter in appreciable quantities. The idea of using
nano-gram amounts of antimatter for the ignition of fission-fusion
microexplosions appears to have credible potential, but even there the
production and storage of nano-gram quantities of antimatter pose serious
technical problems (Reference 4).
We have little reason to expect that new fundamental laws of physics that
could lead to a breakthrough in propulsion still await discovery. Very much as
America was discovered only once, it is quite possible that all the fundamental
laws of physics relevant to propulsion have been discovered, challenging our
imagination to find out if they are sufficient to invent propulsion systems that
ultimately might bring us to Earthlike planets of nearby solar systems.
I conclude this preface with an imaginary talk by Ted Taylor to Freeman Dyson
as recorded by the latter's son, George Dyson, in his book Project Orion - The
True Story of the Atomic Spaceship (Reference 5), followed by a dream of Ted
Taylor's. "Freeman's hope for the Orion had rested on the fact that there
seems to be no law of nature forbidding the construction of fission-free
bombs," and on the belief that "improvements in the design of the nuclear
devices (by reducing the fraction of total yield due to fission) might achieve
reduction factors of 102 to 103• This belief in small, fission-free bombs has
largely evaporated." "One exception is Ted (Taylor). He remains convinced
that small, clean bombs could propel Orion - but he still fears more than ever
that such devices would be irresistible as weapons, until we outgrow the habit
of war. There are lots of different routes to that final result of a very clean
bomb." "Could you make a one-kiloton explosion in which the fission yield was
zero, which is bad news on the proliferation front, but could turn Orion into
something quite clean?" "Freeman thinks Ted is wrong - and Ted hopes
Freeman is right." I for my part think Freeman is wrong.
Many years later, shortly before his death, Ted Taylor reported: "I had a dream
last night, about a new form of nuclear weapon, and I am really scared of it."
He reported that when he woke up, he wrote down his dream, and it appeared
scientifically sound and feasible. What was it? We never will know with
certainty, but I have a guess: it is the possibility of chemical superexplosives
(explained in the appendix) powerful enough to ignite a thermonuclear bomb.
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Introduction
As Hermann Oberth proved for chemical rockets in his 1923 book The Rocket into
Planetary Space (Reference 6), this paper will try to prove for thermonuclear rockets
the following:
• At the present state of science and technology one can build spaceships driven by
deuterium thermonuclear reactions, able to reach the outer limits of the solar
system.
• Such spaceships permit the manned exploration of the entire solar system and
beyond, with the ultimate potential to reach nearby solar systems.
• The cost in research and development to build such spaceships will be high but still
well within what is economically feasible.
• Using the same physical principles as for deuterium fusion rockets will also lead to
the realization of clean nuclear energy, justifying the expenditures for these large
projects.
Deuterium can be used as the rocket fuel of choice in addition to any inert material that
is suitable as a propellant. This propellant material is available on most planetary
bodies and particularly on the comets of the Oort cloud. The main idea is that by
gradual radial expansion from the Sun by building bridges over the Oort clouds, which
presumably surround all suns, Earthlike planets in neighboring solar systems can
eventually be reached.
The first and most important step toward this goal is to reach the focus of the Einstein
gravitational lens at 550 AU (astronomical units). At this location, one can use the Sun
as the lens of a super telescope, an idea first proposed by Claudio Maccone in 1993.
Present knowledge is that there are planets in nearby solar systems that are likely
Earthlike planets. It is only with this gigantic telescope that one can determine if life on
these planets is possible. But because of the complexity of this task, a manned mission
to the Einstein gravitational lens focus is likely to be needed, possible only with
advanced nuclear rocket propulsion.
Deuterium, Argon Ion Lasers, and KeV Superexplosives
The goal is a spacecrah that can be refueled while landing on a planetary body, which
can be a planet, an asteroid, or a comet. With heavy water available on many planetary
bodies but in particular on comets, this suggests the use of deuterium (D) as the
thermonuclear rocket fuel. Ignition of deuterium though, is more difficult than ignition
of the deuterium-tritium (DT) reaction or of the deuterium-helium3 (DHe3) reaction.
The DT reaction is the easiest to ignite, but 80 percent of the energy goes into
neutrons, which cannot be deflected by a magnetic mirror. In the DHe3 reaction all the
energy goes into charged fusion products, but in a mixture of D with He3 there are still
some neutron-producing deuterium-deuterium (DD) reactions. More important is the
fact that, unlike deuterium, He3 is largely unavailable. There is some indication of He3
on the surface of Moon. In the Daedalus starship study by the British Interplanetary
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Society, it was proposed to "mine" He3 from the atmosphere of Jup