Books by Dewar, James A.

Dewar, James with Robert Bussard. The Nuclear Rocket. Burlington, Canada: Apogee Books, 2009. ISBN 978-1-894959-99-5.

Let me begin with a few comments about the author attribution of this book. I have cited it as given on the copyright page, but as James Dewar notes in his preface, the main text of the book is entirely his creation. He says of Robert Bussard, “I am deeply indebted to Bob's contributions and consequently list his name in the credit to this book”. Bussard himself contributes a five-page introduction in which he uses, inter alia, the adjectives “amazing”, “strange”, “remarkable”, “wonderful”, “visionary”, and “most odd” to describe the work, which he makes clear is entirely Dewar's. Consequently, I shall subsequently use “the author” to denote Dewar alone. Bussard died in 2007, two years before the publication of this book, so his introduction must have been based upon a manuscript. I leave to the reader to judge the propriety of posthumously naming as co-author a prominent individual who did not write a single word of the main text.

Unlike the author's earlier To the End of the Solar System (June 2008), which was a nuts and bolts history of the U.S. nuclear rocket program, this book, titled The Nuclear Rocket, quoting from Bussard's introduction, “…is not really about nuclear rocket propulsion or its applications to space flight…”. Indeed, although some of the nitty-gritty of nuclear rocket engines are discussed, the bulk of the book is an argument for a highly-specific long term plan to transform human access to space from an elitist government run program to a market-driven expansive program with the ultimate goal of providing access to space to all and opening the solar system to human expansion and eventual dominion. This is indeed ambitious and visionary, but of all of Bussard's adjectives, the one that sticks with me is “most odd”.

Dewar argues that the NERVA B-4 nuclear thermal rocket core, developed between 1960 and 1972, and successfully tested on several occasions, has the capability, once the “taboo” against using nuclear engines in the boost to low Earth orbit (LEO) is discarded, of revolutionising space transportation and so drastically reducing the cost per unit mass to orbit that it would effectively democratise access to space. In particular, he proposes a “Re-core” engine which, integrated with a liquid hydrogen tank and solid rocket boosters, would be air-launched from a large cargo aircraft such as a C-5, with the solid rockets boosting the nuclear engine to around 30 km where they would separate for recovery and the nuclear engine engaged. The nuclear rocket would continue to boost the payload to orbital insertion. Since the nuclear stage would not go critical until having reached the upper atmosphere, there would be no radioactivity risk to those handling the stage on the ground prior to launch or to the crew of the plane which deployed the rocket.

After reaching orbit, the payload and hydrogen tank would be separated, and the nuclear engine enclosed in a cocoon (much like an ICBM reentry vehicle) which would de-orbit and eventually land at sea in a region far from inhabited land. The cocoon, which would float after landing, would be recovered by a ship, placed in a radiation-proof cask, and returned to a reprocessing centre where the highly radioactive nuclear fuel core would be removed for reprocessing (the entire launch to orbit would consume only about 1% of the highly enriched uranium in the core, so recovering the remaining uranium and reusing it is essential to the economic viability of the scheme). Meanwhile, another never critical core would be inserted in the engine which, after inspection of the non-nuclear components, would be ready for another flight. If each engine were reused 100 times, and efficient fuel reprocessing were able to produce new cores economically, the cost for each 17,000 pound payload to LEO would be around US$108 per pound.

Payloads which reached LEO and needed to go beyond (for example, to geostationary orbit, the Moon, or the planets) would rendezvous with a different variant of the NERVA-derived engine, dubbed the “Re-use” stage, which is much like Von Braun's nuclear shuttle concept. This engine, like the original NERVA, would be designed for multiple missions, needing only inspection and refuelling with liquid hydrogen. A single Re-use stage might complete 30 round-trip missions before being disposed of in deep space (offering “free launches” for planetary science missions on its final trip into the darkness).

There is little doubt that something like this is technically feasible. After all, the nuclear rocket engine was extensively tested in the years prior to its cancellation in 1972, and NASA's massive resources of the epoch examined mission profiles (under the constraint that nuclear engines could be used only for departure from LEO, however, and without return to Earth) and found no show stoppers. Indeed, there is evidence that the nuclear engine was cancelled, in part, because it was performing so well that policy makers feared it would enable additional costly NASA missions post-Apollo. There are some technological issues: for example, the author implies that the recovered Re-core, once its hot core is extracted and a new pure uranium core installed, will not be radioactive and hence safe to handle without special precautions. But what about neutron activation of other components of the engine? An operating nuclear rocket creates one of the most extreme neutronic environments outside the detonation of a nuclear weapon. Would it be possible to choose materials for the non-core components of the engine which would be immune to this and, if not, how serious would the induced radioactivity be, especially if the engine were reused up to a hundred times? The book is silent on this and a number of other questions.

The initial breakthrough in space propulsion from the first generation nuclear engines is projected to lead to rapid progress in optimising them, with four generations of successively improved engines within a decade or so. This would eventually lead to the development of a heavy lifter able to orbit around 150,000 pounds of payload per flight at a cost (after development costs are amortised or expensed) of about US$87 per pound. This lifter would allow the construction of large space stations and the transport of people to them in “buses” with up to thirty passengers per mission. Beyond that, a nuclear single stage to orbit vehicle is examined, but there are a multitude of technological and policy questions to be resolved before that could be contemplated.

All of this, however, is not what the book is about. The author is a passionate believer in the proposition that opening the space frontier to all the people of Earth, not just a few elite civil servants, is essential to preserving peace, restoring the optimism of our species, and protecting the thin biosphere of this big rock we inhabit. And so he proposes a detailed structure for accomplishing these goals, beginning with “Democratization of Space Act” to be adopted by the U.S. Congress, and the creation of a “Nuclear Rocket Development and Operations Corporation” (NucRocCorp), which would be a kind of private/public partnership in which individuals could invest. This company could create divisions (in some cases competing with one another) and charter development projects. It would entirely control space nuclear propulsion, with oversight by U.S. government regulatory agencies, which would retain strict control over the fissile reactor cores.

As the initial program migrated to the heavy lifter, this structure would morph into a multinational (admitting only “good” nations, however) structure of bewildering (to this engineer) bureaucratic complexity which makes the United Nations look like the student council of Weemawee High. The lines of responsibility and power here are diffuse in the extreme. Let me simply cite “The Stockholder's Declaration” from p. 161:

Whoever invests in the NucRocCorp and subsequent Space Charter Authority should be required to sign a declaration that commits him or her to respect the purpose of the new regime, and conduct their personal lives in a manner that recognizes the rights of their fellow man (What about woman?—JW). They must be made aware that failure to do so could result in forfeiture of their investment.

Property rights, anybody? Thought police? Apart from the manifest baroque complexity of the proposed scheme, it entirely ignores Jerry Pournelle's Iron Law of Bureaucracy: regardless of its original mission, any bureaucracy will eventually be predominately populated by those seeking to advance the interests of the bureaucracy itself, not the purpose for which it was created. The structure proposed here, even if enacted (implausible in the extreme) and even if it worked as intended (vanishingly improbable), would inevitably be captured by the Iron Law and become something like, well, NASA.

On pp. 36–37, the author likens attempts to stretch chemical rocket technology to its limits to gold plating a nail when what is needed is a bigger hammer (nuclear rockets). But this book brings to my mind another epigram: “When all you have is a hammer, everything looks like a nail.” Dewar passionately supports nuclear rocket technology and believes that it is the way to open the solar system to human settlement. I entirely concur. But when it comes to assuming that boosting people up to a space station (p. 111):

And looking down on the bright Earth and into the black heavens might create a new perspective among Protestant, Roman Catholic, and Orthodox theologians, and perhaps lead to the end of the schism plaguing Christianity. The same might be said of the division between the Sunnis and Shiites in Islam, and the religions of the Near and Far East might benefit from a new perspective.

Call me cynical, but I'll wager this particular swing of the hammer is more likely to land on a thumb than the intended nail. Those who cherish individual freedom have often dreamt of a future in which the opening of access to space would, in the words of L. Neil Smith, extend the human prospect to “freedom, immortality, and the stars”—works for me. What is proposed here, if adopted, looks more like, after more than a third of a century of dithering, the space frontier being finally opened to the brave pioneers ready to homestead there, and when they arrive, the tax man and the all-pervasive regulatory state are already there, up and running. The nuclear rocket can expand the human presence throughout the solar system. Let's just hope that when humanity (or some risk-taking subset of it) takes that long-deferred step, it does not propagate the soft tyranny of present day terrestrial governance to worlds beyond.

October 2009 

Dewar, James A. To the End of the Solar System. 2nd. ed. Burlington, Canada: Apogee Books, [2004] 2007. ISBN 978-1-894959-68-1.

If you're seeking evidence that entrusting technology development programs such as space travel to politicians and taxpayer-funded bureaucrats is a really bad idea, this is the book to read. Shortly after controlled nuclear fission was achieved, scientists involved with the Manhattan Project and the postwar atomic energy program realised that a rocket engine using nuclear fission instead of chemical combustion to heat a working fluid of hydrogen would have performance far beyond anything achievable with chemical rockets and could be the key to opening up the solar system to exploration and eventual human settlement. (The key figure of merit for rocket propulsion is “specific impulse”, expressed in seconds, which [for rockets] is simply an odd way of expressing the exhaust velocity. The best chemical rockets have specific impulses of around 450 seconds, while early estimates for solid core nuclear thermal rockets were between 800 and 900 seconds. Note that this does not mean that nuclear rockets were “twice as good” as chemical: because the rocket equation gives the mass ratio [mass of fuelled rocket versus empty mass] as exponential in the specific impulse, doubling that quantity makes an enormous difference in the missions which can be accomplished and drastically reduces the mass which must be lifted from the Earth to mount them.)

Starting in 1955, a project began, initially within the U.S. Air Force and the two main weapons laboratories, Los Alamos and Livermore, to explore near-term nuclear rocket propulsion, initially with the goal of an ICBM able to deliver the massive thermonuclear bombs of the epoch. The science was entirely straightforward: build a nuclear reactor able to operate at a high core temperature, pump liquid hydrogen through it at a large rate, expel the hot gaseous hydrogen through a nozzle, and there's your nuclear rocket. Figure out the temperature of exhaust and the weight of the entire nuclear engine, and you can work out the precise performance and mission capability of the system. The engineering was a another matter entirely. Consider: a modern civil nuclear reactor generates about a gigawatt, and is a massive structure enclosed in a huge containment building with thick radiation shielding. It operates at a temperature of around 300° C, heating pressurised water. The nuclear rocket engine, by comparison, might generate up to five gigawatts of thermal power, with a core operating around 2000° C (compared to the 1132° C melting point of its uranium fuel), in a volume comparable to a 55 gallon drum. In operation, massive quantities of liquid hydrogen (a substance whose bulk properties were little known at the time) would be pumped through the core by a turbopump, which would have to operate in an almost indescribable radiation environment which might flash the hydrogen into foam and would certainly reduce all known lubricants to sludge within seconds. And this was supposed to function for minutes, if not hours (later designs envisioned a 10 hour operating lifetime for the reactor, with 60 restarts after being refuelled for each mission).

But what if it worked? Well, that would throw open the door to the solar system. Instead of absurd, multi-hundred-billion dollar Mars programs that land a few civil servant spacemen for footprints, photos, and a few rocks returned, you'd end up, for an ongoing budget comparable to that of today's grotesque NASA jobs program, with colonies on the Moon and Mars working their way toward self-sufficiency, regular exploration of the outer planets and moons with mission durations of years, not decades, and the ability to permanently expand the human presence off this planet and simultaneously defend the planet and its biosphere against the kind of Really Bad Day that did in the dinosaurs (and a heck of a lot of other species nobody ever seems to mention).

Between 1955 and 1973, the United States funded a series of projects, usually designated as Rover and NERVA, with the potential of achieving all of this. This book is a thoroughly documented (65 pages of end notes) and comprehensive narrative of what went wrong. As is usually the case when government gets involved, almost none of the problems were technological. The battles, and the eventual defeat of the nuclear rocket were due to agencies fighting for turf, bureaucrats seeking to build their careers by backing or killing a project, politicians vying to bring home the bacon for their constituents or kill projects of their political opponents, and the struggle between the executive and legislative branches and the military for control over spending priorities.

What never happened among all of the struggles and ups and downs documented here is an actual public debate over the central rationale of the nuclear rocket: should there be, or should there not be, an expansive program (funded within available discretionary resources) to explore, exploit the resources, and settle the solar system? Because if no such program were contemplated, then a nuclear rocket would not be required and funds spent on it squandered. But if such a program were envisioned and deemed worthy of funding, a nuclear rocket, if feasible, would reduce the cost and increase the capability of the program to such an extent that the research and development cost of nuclear propulsion would be recouped shortly after the resulting technology were deployed.

But that debate was never held. Instead, the nuclear rocket program was a political football which bounced around for 18 years, consuming 1.4 billion (p. 207) then-year dollars (something like 5.3 billion in today's incredible shrinking greenbacks). Goals were redefined, milestones changed, management shaken up and reorganised, all at the behest of politicians, yet through it all virtually every single technical goal was achieved on time and often well ahead of schedule. Indeed, when the ball finally bounced out of bounds and the 8000 person staff was laid off, dispersing forever their knowledge of the “black art” of fuel element, thermal, and neutronic design constraints for such an extreme reactor, it was not because the project was judged infeasible, but the opposite. The green eyeshade brigade considered the project too likely to succeed, and feared the funding requests for the missions which this breakthrough technological capability would enable. And so ended the possibility of human migration into the solar system for my generation. So it goes. When the rock comes down, the few transient survivors off-planet will perhaps recall their names; they are documented here.

There are many things to criticise about this book. It is cheaply made: the text is set in painfully long lines in a small font with narrow margins, which require milliarcsecond-calibrated eye muscles to track from the end of a line to the start of the next. The printing lops off the descenders from the last line of many pages, leaving the reader to puzzle over words like “hvdrooen” and phrases such as “Whv not now?”. The cover seems to incorporate some proprietary substance made of kangaroo hair and discarded slinkies which makes it curl into a tube once you've opened it and read a few pages. Now, these are quibbles which do not detract from the content, but then this is a 300 page paperback without a single colour plate with a cover price of USD26.95. There are a number of factual errors in the text, but none which seriously distort the meaning for the knowledgeable reader; there are few, if any, typographical errors. The author is clearly an enthusiast for nuclear rocket technology, and this sometimes results in over-the-top hyperbole where a dispassionate recounting of the details should suffice. He is a big fan of New Mexico senator Clinton Anderson, a stalwart supporter of the nuclear rocket from its inception through its demise (which coincided with his retirement from the Senate due to health reasons), but only on p. 145 does the author address the detail that the programme was a multi-billion dollar (in an epoch when a billion dollars was real money) pork barrel project for Anderson's state.

Flawed—yes, but if you're interested in this little-known backstory of the space program of the last century, whose tawdry history and shameful demise largely explains the sorry state of the human presence in space today, this is the best source of which I'm aware to learn what happened and why. Given the cognitive collapse in the United States (Want to clear a room of Americans? Just say “nuclear!”), I can't share the author's technologically deterministic optimism, “The potential foretells a resurgence at Jackass Flats…” (p. 195), that the legacy of Rover/NERVA will be redeemed by the descendants of those who paid for it only to see it discarded. But those who use this largely forgotten and, in the demographically imploding West, forbidden knowledge to make the leap off our planet toward our destiny in the stars will find the experience summarised here, and the sources cited, an essential starting point for the technologies they'll require to get there.

“ ‘Und I'm learning Chinese,’ says Wernher von Braun.”

June 2008