By Lori Stiles - University of Arizona
University
of Arizona Regents' Professor J. Randolph Jokipii of the Lunar
and Planetary Laboratory has been elected to the National Academy
of Sciences, one of the most prestigious honors in American science.
The Academy,
chartered in 1863 by President Abraham Lincoln to guide public
action in science, yesterday elected 72 new members and 15 foreign
associates from 10 countries in recognition of their distinguished
and continuing achievements in original research.
Jokipii said
he learned of his election while at breakfast with his wife yesterday
in a 6 a.m. phone call from Washington, D.C. "I'm pretty
happy," Jokipii said. "For me, this is right up there
with the Regents' Professorship."
Regents' Professor
Donald Hunten, also of the UA Lunar and Planetary Lab, was among
the half-dozen NAS members at the Capitol to congratulate Jokipii
over the phone. Jokipii joins Hunten as a member of the NAS geophysics
section.
Rice University
Provost Gene Levy said, "Randy has been the most sustained,
focused and creatively productive researcher in the field of theoretical
cosmic ray physics in the world in the past 30 years. This is
clearly the basis for his richly deserved election to the Academy."
Levy, former dean of the UA College of Science, collaborated with
Jokipii on cosmic ray research at UA from 1974-1980.
Jokipii's
work in theoretical and space physics covers many areas primarily
related to the transport and acceleration of cosmic rays and energetic
particles in the solar wind and in the galaxy.
A consistent
focus of his research has been on the effect of the sun's magnetic
field and the solar wind on galactic cosmic rays. The sun's magnetic
field, which dominates the environment of our solar system out
to 100 AU (100 times the distance between Earth and the sun),
deflects incoming galactic cosmic rays.
Scientists
have long known that this "solar modulation of cosmic rays"
varies with the sunspot cycle.
Jokipii played
a fundamental role in developing theory that explains how the
solar wind and the solar magnetic field inhibit cosmic ray entry
into the solar system. His work has proved what 25 years ago was
Levy's and his heretical suggestion - that the polarity of the
sun's magnetic field affects how the sun modulates the cosmic
rays bombarding our solar system.
"Jokipii
developed the accepted theory for the variation of cosmic rays
in the heliosphere as determined by the solar cycle," said
UA planetary sciences Professor Bill Hubbard. "It's a fairly
arcane theory not easily explained, but the upshot is that it
has predicted things that have been observed by spacecraft.
"While
what Randy does is not exactly what I do, I've written some papers
with him. It was a stimulating experience. I immediately knew
I was working with a very smart man," Hubbard added.
Jokipii was
an interdisciplinary scientist on the joint European Space Agency/NASA
Ulysses mission launched to the sun in 1992. He and his team interpret
Ulysses spacecraft observations made at the sun's poles in developing
their theoretical models. Ulysses made a first-ever polar pass
of the sun, over the south pole, in 1995, and a year later, a
pass over the north solar pole. This period was one of low sun
spot activity. After a gravity-assist swing around Jupiter, Ulysses
is again poised for solar passes - this time during high sun spot
activity.
Jokipii and
his group are also guest investigators on NASA's ACE mission,
the Anomalous and Composition Explorer spacecraft. Launched in
1997, ACE sits at the "L-1" point between Earth and
sun where it measures cosmic rays. \ A native of Michigan, Jokipii
earned an undergraduate degree from the University of Michigan
and, in 1965, his doctorate from the California Institute of Technology.
His doctoral dissertation concerned the solar wind and energetic
particles. He joined the University of Arizona faculty in 1974.
Jokipii is
a Fellow of the American Geophysical Union and a Fellow of the
American Physical Society. Other memberships and committee positions
include the International Astronomical Union, International Academy
of Astronautics, NASA Space Physics Committee and the Academy
of Science Ad Hoc Cosmic Ray Physics Committee.
Contact information:
J. Randolph Jokipii 520-621-4256, jokipii@lpl.arizona.edu
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