Nuclear Isomer Decay: A Possibility for Breakthrough Space

[Wes Van Pelt <vanpeltw@idt.net>]

Radsafers,

The below fascinating abstract is about inducing gamma decay as a deep space
propulsion method.
Can anyone explain:
    How can isomeric transition be triggered?
    How can the resulting gamma rays be made to go in one direction so as to
produce propulsion. I thought the direction of gammas must be isotropic.
Regards,
Wes
--
Wesley R. Van Pelt, Ph.D., CIH, CHP            KF2LG
President, Van Pelt Associates
Radiation Safety and Environmental Radioactivity
mailto:vanpeltw@idt.net    http://idt.net/~vanpeltw/


 Title:        Nuclear Isomer Decay: A Possibility for Breakthrough Space
               Propulsion
 Document ID:  19990023229
 Report #:     None
 Sales Agency: CASI Hardcopy A01
               CASI Microfiche A04
               No Copyright
 Authors:      Carpenter, Phillip A. (Oak Ridge Operations Office)
               Gat, Uri (Oak Ridge National Lab.)
 Journal:      NASA Breakthrough Propulsion Physics Workshop Proceedings,
               Page: 217-220
 Published:    19990101
 Source:       Oak Ridge National Lab. (TN United States)
 Pages:        4
 Contract #:   DE-AC05-96OR-22464
 Abstract:     A novel propulsion system for deep space missions that
               utilizes accelerated decay of nuclear isomers via induced
               gamma emission is proposed. The propulsion is accomplished
               by ejection of gamma particles resulting from controlled
               nuclear isomeric decay. The specific impulse per unit mass
               is comparable with that of chemical-thermal sources;
               however, the specific energy comparison on the same basis
               is about five orders of magnitude higher. It is expected
               that the nuclear isomers can be recharged while in space by
               gamma rays to "pump-up" the isomers. A prime candidate for
               this application is the isotope Hf-178. The nuclear
               isomeric transition is a transition of an excited nucleus
               to its ground state by release of energy as gamma
               particles. The accelerated nuclear decay is accomplished by
               further exciting the isomer so that the degree of
               forbiddenness of transition to the ground state is reduced
               and occurs rapidly. The recharging is done by supplying
               energy in quantities that recreate the decay inhibited
               state. The rechargeability of the isomers in space makes
               accelerated nuclear decay attractive for long space
               missions. It may be possible to collect gamma rays while
               traveling in space to recharge the isomers. Further, it is
               possible that with controlled releases, the non-propulsion
               energy requirements of the spacecraft can also be met.
               Onboard power could be provided through the controlled
               release of gamma rays (i.e., photons) which can be
               converted to electricity via photoelectric or other effect.
               On long trips, gathered energy from space can be used for
               continued acceleration for about the first half of the trip
               and then for deceleration for the remaining half of the
               trip. The photons momentum provides the propulsion
               momentum. This concept is akin to the early light-sail
               (i.e., photon pressure propulsion) concepts as proposed,
               for example, by Dr. Robert L. Forward in the 1970s, and
               earlier by others. The major initial development areas
               proposed are: verification and confirmation of the
               principles; establish theory and develop physical control;
               quantitative control of energy and impulse release;
               direction and collimation of the release; development of
               the recharge ("pump-up") mechanism of the isomers and the
               controlled triggering of release(s); concept definition of
               applications as propulsion; and as an onboard energy
               storage and generation source.
 Language:     English


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