@S1-A.ARPA,@MIT-MC:jheimann@bbnccy (05/16/85)
From: John H. Heimann <jheimann@BBNCCY.ARPA> Rather than going down to the local library and reading through old NASA annual reports, I'm going to cop out and submit this question to the net. Back in the 'sixties, there were a number of programs (funded, I think, by NASA and what was then AEC) to develop nuclear powered space propulsion schemes. The ones I recall are project Orion, which involved the detonation of tiny fission explosives behind a so-called bumper plate which was connected to the rear of a spacecraft. The explosion byproducts would impart momentum to the plate, and thence to the craft. The other program was intended to develop a more traditional rocket motor, in which hydrogen gas was heated in a fission reactor and allowed to expand through a nozzle. Neither program culminated in the flight test of an engine, although the hydrogen/reactor rocket was ground tested (Project Kiwi, as I recall). In theory at least, a nuclear rocket should be more efficient than a chemical rocket, since the exhaust gasses can be made much hotter. I may be mistaken, but I think the lower molecular weight of the exhaust gas of a nuclear rocket (atomic H) compared with that of, say, a hydrocarbon-LOX chemical rocket (H2O and CO2) gives nuclear rockets a further advantage in thrust. My question is, why were these projects cancelled? I can imagine that project Orion would violate the Limited Nuclear Test Ban Treaty, which prohibits atmospheric or outer-space testing of nuclear weapons. The main reason I can think of for cancelling the hydrogen/reactor engine is concern about radioactive exhaust or, if the rocket should crash, radioactive waste. Neither of these concerns would be legitimate if the engine were used well outside the earth's atmosphere. There is of course the problem of getting a fission reactor safely into orbit. A few tons of plutionium oxide, molten from reentry, would not be the nicest thing to have falling into one's backyard. John
@S1-A.ARPA,@MIT-MC:METH@USC-ISI.ARPA (05/17/85)
From: METH@USC-ISI.ARPA
You hit the reasons right on the nose. Several space nuclear
propulsion programs (NERVA, KIWI, RBR) were cancelled because of
the fear (political rather than technical, I suspect) of
transporting large amounts of nuclear material into space.
There is a revitalized interest in space nuclear power, if
not propulsion. The SP-100 program, initially funded by DARPA,
NASA, and DOE was looking at such concepts (as well as non-nuclear
ones) for 100kW(e). I believe that has transitioned to SDIO.
SDI/SLKT (Survivability, Lethality, and Key Technologies) and
SDI/IST (Innovative Science and Technology) offices are interested
in such power sources. DOE is sponsoring a New and Innovative
Concepts program (PRDA DE-RA03-85SF15622) which also includes new
space power (including nuclear) concepts. Many of the new space
nuclear power concepts could be used for propulsion.
-Sheldon Meth
-------@S1-A.ARPA,@MIT-MC:DOLANTP@USC-ISI.ARPA (05/18/85)
From: DOLANTP@USC-ISI.ARPA
The United States began research into using nuclear power for rocket
propulsion back in the late 1950s. Back then, it seemed that the power
which could be generated using nuclear means was a lot more promising than
chemical rockets.
Project Orion went through several design stages, one of the more interest-
ing of which called for a 300-foot-tall vehicle with a combustion containment
chamber made of 1/2-inch steel. This chamber was supposed to be 150 feet
in diameter, and small (0.1 kiloton) nuclear devices would be exploded in
the center of the chamber. Thrust would be generated via water injection
into the chamber, and subsequent vaporization.
The Project Kiwi engines reportedly could have powered a vehicle into low
earth orbit, and showed some promise. However, if you remember the years
(early 1960s) of these experiments, we had a sudden push to get a man on the
Moon in a hurry. The nuclear rocket research was not progressing fast
enough, so funds were redirected to more conventional means of propulsion.
Another attempt at nuclear propulsion sources was the Air Force attempt to
make a nuclear airplane. General Electric actually did make a prototype
reactor which drove two turbine engines, and in the early 1960s USAF
predicted that their first nuclear airplane would fly by 1965. It didn't.
Most of the action was generated by a fear that we had to get these devices
flying before the Soviets did. When it became obvious that neither side was
making progress, the urgency subsided.
This research could probably make the basis of an interesting book, if any-
one cared to write it.
Tom Dolan
Naval Postgraduate School
Monterey, CA
-------henry@utzoo.UUCP (Henry Spencer) (05/19/85)
> My question is, why were these projects cancelled?
Project Orion was ultimately killed by the Limited Nuclear Test Ban Treaty,
as you speculated, but it was already languishing for lack of support. The
more conventional nuclear-rocket program was killed, just as it was getting
real results, simply because it was expensive and there was no mission in
sight (i.e. realistically planned, as opposed to passionately desired) that
would require a nuclear rocket.
Nuclear rockets basically died because NASA decided to use chemical rockets
to get to the moon, and all the ambitious followon projects that might have
provided later requirements for nuclear rockets got killed by budgets.
--
Henry Spencer @ U of Toronto Zoology
{allegra,ihnp4,linus,decvax}!utzoo!henryrdp@teddy.UUCP (07/16/85)
In article <1839@mordor.UUCP> @S1-A.ARPA,@MIT-MC:jheimann@bbnccy writes: >From: John H. Heimann <jheimann@BBNCCY.ARPA> > > > Back in the 'sixties, there were a number of programs (funded, I think, >by NASA and what was then AEC) to develop nuclear powered space propulsion >schemes. The ones I recall are project Orion, which involved the detonation of > > My question is, why were these projects cancelled? I can imagine that >project Orion would violate the Limited Nuclear Test Ban Treaty, which >prohibits atmospheric or outer-space testing of nuclear weapons. The main >reason I can think of for cancelling the hydrogen/reactor engine is concern >about radioactive exhaust or, if the rocket should crash, radioactive waste. >Neither of these concerns would be legitimate if the engine were used well >outside the earth's atmosphere. There is of course the problem of getting a >fission reactor safely into orbit. A few tons of plutionium oxide, molten from >reentry, would not be the nicest thing to have falling into one's backyard. > The use of nuclear propulsion tended (in the case of the non-explosive technique) to result in extremely high exhaust velocities and very high efficiencies, but extremely low thrusts. I recall hearing of thrusts in the neighborhood of ounces! Such propulsion methods are useful when you can tolerate long durations of firings (months or years) and do not need tremendous accelerations. For near-earth and earth-moon manned missions, and the like, what was needed was lots of thrust over short periods of time, the kinf of things chemical rockets are good at.
jamesp@dadla.UUCP (Jim Perkins) (07/23/85)
In article <939@teddy.UUCP> rdp@teddy.UUCP (Richard D. Pierce) writes: >In article <1839@mordor.UUCP> @S1-A.ARPA,@MIT-MC:jheimann@bbnccy writes: >>From: John H. Heimann <jheimann@BBNCCY.ARPA> >> >> >> Back in the 'sixties, there were a number of programs (funded, I think, >>by NASA and what was then AEC) to develop nuclear powered space propulsion >>schemes.... > >The use of nuclear propulsion tended (in the case of the non-explosive >technique) to result in extremely high exhaust velocities and very high >efficiencies, but extremely low thrusts. I recall hearing of thrusts in the >neighborhood of ounces! Such propulsion methods are useful when you can >tolerate long durations of firings (months or years) and do not need >tremendous accelerations. For near-earth and earth-moon manned missions, and >the like, what was needed was lots of thrust over short periods of time, the >kinf of things chemical rockets are good at. Quite true. I believe you are talking about some sort of nuclear/ion engine... wasn't there some type that used a hot reactor to heat, say, hydrogen gas that produced respectible thrust? The method as I understood it had a an inner and an outer fissile cylinder, and the reaction mass was passed between them, heated, and expelled to the exterior. Other methods used gaseous(?) fissile materials, and used a helical mixing method and centrifugal reaction chambers where the fissioning gas was concentrated on the exterior of the reaction chamber. All these methods were of course theoretical. I wonder how much research has been done on these and what the results were... =============================================================================== | James T. Perkins | uucp: ...!decvax!tektronix!dadla!jamesp | "Roads?! Where | \ | / | \@_ (snail): 4635 SW Hillside Dr. | we're going we | -- O -- | Portland, OR 97221 | don't NEED | / | \ | Bell: (503)292-4614 | roads..." ===============================================================================
dls@mtgzz.UUCP (d.l.skran) (07/31/85)
Why projects were canceled:
My understanding is as follows:
Orion: 1)testing would violate test-ban treaty
2)MORE IMPORTANT: no clear mission requirement for aircraft carrier
size rockets. Military decided they didn't need one.
Nerva: 1)insufficient advantage over chemical rockets to
compenstate for all the extra trouble.
Note: Nerva was not a "low thrust" program. Its thrust was
quite similar to chemical rockets. I believe you are confusing
ion & plasma rockets(which are low thrust) with nuclear rockets.
Frequently, an ion/plasma rocket design might call for a nuclear
reactor to produce electricity, but other power sources could
have been used.
Why not today:
Nerva: same reason, insufficient advantage for all the trouble.
Orion: the smaller the explosions, the higher the efficiency. Hence,
many people are working on particle/laser beam induced fusion
which could be used to create a rocket an order of magnitude better
than orion.
Really, though, we've got no guts, no reason to build Orion.
Read Niven & Pournelle's new novel Footfall for some idea of what an
Orion ship might be like and how it could be used.
Dalemojo@kepler.UUCP (Morris Jones) (08/05/85)
Does anyone have a vague idea of what kind of G forces the crew of a
nuclear rocket a la Footfall would be subjected to? Missing data
from the book includes the mass (inertia) of the Archangel, and the
size of the bombs used to propel it. I kept thinking during the book
that we were talking bone-crushing acceleration here -- especially
from a ground launch.
--
Mojo
... Morris Jones, MicroPro Product Development
{dual,ptsfa,hplabs}!well!micropro!kepler!mojo