Published on Dec 28, 2011
Dr.
France Cordova, NASA's Chief Scientist, chaired this, the eighth
seminar in the Administrator's Seminar Series. She introduced the NASA
Administrator, Daniel S. Goldin, who, in turn, introduced the subject of
plasma. Plasma, an ionized gas, is a function of temperature and
density. We ve learned that, at Jupiter, the radiation is dense. But,
Goldin asked, what else do we know? Dr. Cordova then introduced Dr.
James Van Allen, for whom the Van Allen radiation belt was named. Dr.
Van Allen, a member of the University of Iowa faculty, discussed the
growing interest in practical applications of space physics, including
radiation fields and particles, plasmas and ionospheres. He listed a
hierarchy of magnetic fields, beginning at the top, as pulsars, the Sun,
planets, interplanetary medium, and interstellar medium. He pointed out
that we have investigated eight of the nine known planets,. He listed
three basic energy sources as 1) kinetic energy from flowing plasma such
as constitutional solar wind or interstellar wind; 2) rotational energy
of the planet, and 3) orbital energy of satellites. He believes there
are seven sources of energetic particles and five potential places where
particles may go. The next speaker, Dr. Ian Axford of New Zealand, has
been associated with the Max Planck Institut fuer Aeronomie and plasma
physics. He has studied solar and galactic winds and clusters of
galaxies of which there are several thousand. He believes that the solar
wind temperature is in the millions of degrees. The final speaker was
Dr. Roger Blanford of the California Institute of Technology. He
classified extreme plasmas as lab plasmas and cosmic plasmas. Cosmic
plasmas are from supernovae remnants. These have supplied us with heavy
elements and may come via a shock front of 10(sup 15) electron volts. To
understand the physics of plasma, one must learn about x-rays, the
maximum energy of acceleration by supernova remnants, particle
acceleration and composition of cosmic rays, maximum acceleration, and
how fast protons are heated by ions. He asked questions about where high
energy cosmic rays are made, what accelerates electrons, radiates gamma
rays, makes electronpositron plasma, and finally noted that pulsars are
good time keepers, but we need a better understanding of their
mechanism and of plasmas, both cosmic and ground-based. In the
discussion period, Goldin asked if NASA should put up an x-ray
interferometer. The answer was no; gamma rays are of greater interest
just now. Goldin also asked what the assembled scientists would like to
see for a future mission? They expressed an interest in learning more
about the origin of galaxies, cosmic rays, solar systems, planets, the
existence of life "out there", gamma ray sources, the nature of gamma
ray bursts, and the flow of gases around black holes. The discussion
concluded with a suggestion that NASA should communicate to the general
public more information regarding actual technological trials and
tribulations involved in getting an experiment to work. The speakers
thought that this would help non-scientists to better appreciate what it
is that NASA does in connection with the benefits that are achieved.
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