- 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 