Roger A. Broucke passed away on Tuesday, June 21, 2005, in Austin, Texas, at
the age of 73. He is survived by his loving wife of forty-five years, Ludgarde
Broucke; his daughters Ingrid Broucke, M.D. and Mireille Broucke, Ph.D.; his
son-in-law Daniel Keleti, M.D.; and grandchildren, Isabel, Alexandra, and Michael
Keleti. He is also survived by his sister, Antoinette Broucke, and brother, Willy
Broucke, of Belgium.
Broucke was born on March 25, 1932, in a farmhouse in Furnes, Belgium. Early
in his life as a farm boy, he acquired an interest in science and mathematics,
a love he maintained throughout his life. At an early age, he was sent to a boarding
school to study mathematics. He earned a B.S. degree in mathematics at the University
of Louvain, Belgium, in 1955 and a master’s degree in mathematics in 1957
where he studied under Professor George LeMaitre, the originator of the Big Bang
Theory on the creation of the universe. In 1958, he entered the military service
in the Belgian army and was stationed in Germany. He continued his graduate studies
at the University of Brussels and earned a second master’s degree in operations
research in 1960. He also worked as a research mathematician at Petrofina Oil
Company in Brussels from 1959 to 1961.
He was fortunate to meet Ludgarde Van de Wiel, whom he married in 1960. Ludgarde,
his devoted companion and friend, shared with him a lifelong passion about learning,
which they passed on to their children. Ludgarde Broucke contributed to the groundbreaking
pictures of periodic orbits in the three-body problem which appeared in her husband’s
Ph.D. thesis, which became one of the significant contributions of his career.
In 1962, Broucke received his Ph.D. in mathematics from the University of Louvain
in Belgium. In 1963, he joined the Jet Propulsion Laboratory (JPL) in Pasadena,
California, as a senior research engineer. For the next thirteen years he was
an integral part of NASA’s space flight program. A pinnacle historical
moment at that stage of his scientific career occurred on July 20, 1969, when
man first walked on the moon.
During these years, some of Broucke’s happiest hours were spent teaching
and mentoring graduate students at several universities while maintaining his
position at JPL. He was a lecturer at West Coast University and the University
of Southern California; in addition, he was an acting associate professor at
the University of California at Los Angeles (UCLA), an adjunct professor, and
finally an associate professor at UCLA between 1969 and 1974.
His desire for more autonomy in his research pursuits led him to accept a position
as associate professor in the Department of Aerospace Engineering and Engineering
Mechanics at The University of Texas at Austin in 1975. He became a full professor
in 1982. He became an internationally renowned scientist in the areas of celestial
mechanics, satellite theory, and particularly, in computational mechanics related
to orbital dynamics. He was one of the first members of the Texas Institute for
Computational Mechanics, officially founded at The University in 1976, and he
began work on a number of projects involving the use of computers and computational
mathematics to model nonlinear dynamics and to solve the governing equations
of complex problems in celestial mechanics. He was an active member of a group
of colleagues involved in applied and computational mathematics research.
Broucke made several fundamental contributions in celestial mechanics. First,
he devoted a significant effort to the investigation of the general and restricted
three-body problems of celestial mechanics. He studied several different variants
of the problem, and he used different forms of a mathematical technique called
regularization to find new classes of trajectories, especially the important
group of periodic orbits. In his Ph.D. dissertation in 1962, he made extensive
numerical studies of the restricted three-body problem corresponding to the Moon-Earth
ratio for two of the masses at a time when computers where just being introduced
in celestial mechanics. In particular, through these studies he presented a classification
of the types of stability and instability of orbits which had never appeared
before. He proposed a principle about how certain orbits transform in the limit
as the ratio of the Moon-Earth masses go to zero. This became known as "Broucke's
Principle" in celestial mechanics, and it was formally proved to be correct
in 1981 by Lawrence Perko.
A second significant contribution of his work was algorithms for the manipulation
of Poisson series, which arise in the computation of orbits in celestial mechanics.
More general mathematical manipulation systems like Mathematica, Reduce, and
Maple were already used in many fields. But these general systems are not useful
for the Poisson series manipulations in celestial mechanics because intermediate
results become too large. Broucke developed a set of algorithms which were widely
distributed because of their machine independence and which have been a foundation
in many problems in celestial mechanics.
The third significant contribution of Broucke's career is the discovery of
a family of periodic orbits in the Anisotropic Kepler problem in celestial
mechanics. Formerly, it had been thought that the system was completely chaotic.
Broucke’s discovery contributed to a shift in thinking in nonlinear dynamics
away from the view that dynamical systems are either integrable or chaotic.
Broucke also made contributions in inverse problems in celestial mechanics,
optimal computation of the solution of the Kepler problem, studies in gravitational
potentials of irregular bodies, and perturbation theory. He applied his theoretical
studies to problems such as the motion of comets and orbital maneuvers required
by artificial satellites with emphasis on swing-by maneuvers.
Broucke was a member of many national and international scientific societies.
He was a member of the American Institute of Aeronautics and Astronautics (AIAA),
the Astronomical Society, the International Astronomical Union, the Society
of Engineering Science, and the American Academy of Mechanics. He was vice
president of the Division of Dynamical Astronomy of the American Astronomical
Society between 1985 and 1986. He was promoted to the grade of Associate Fellow
of the AIAA in 1969, and he received the NASA Apollo Achievement Award in 1973.
Broucke was a member of the editorial board of
Celestial Mechanics,
a member of the Association for Computing Machinery, and a member of the Division
of Dynamical Astronomy of the American Astronomical Society. He was a member
of the Celestial Mechanics Institute, and he became the executive editor of
Celestial
Mechanics in 1973. He published 100 scientific papers on applied mathematics,
celestial mechanics, and orbital dynamics. He supervised over twenty-five students,
including sixteen Ph.D. dissertations and ten master’s theses. In 2002,
he received the Dirk Brouwer Award for his significant and numerous contributions
to the theory of dynamical systems and space flight mechanics. Following his
retirement, he became professor emeritus at The University of Texas at Austin.
Broucke was also interested in foreign languages; he was fluent in Dutch,
French, Spanish, and German. He built one of the first personal computers,
a MITS Altair 8800, in the early 1970s. Among his other hobbies were oil painting,
classical music, and interest in the Human Genome Project.
Broucke’s
daughter, Mireille, remembers his technical interests as being primarily focused
on mathematical dynamics.
For him, mathematics was a sanctuary of order and beauty, unlike the human world with its contradictions and inexplicable sufferings. He had an uncluttered interpretation of scientific subjects, which was born out of a love of simple, but decisive pictures. Indeed, much of his career was focused on producing decisive pictures to explain and expose phenomena in celestial mechanics. What most inspired me about him were his essential rationality, his conviction that through disciplined reflection, the human mind can put an order into a seemingly unstructured reality, his humility, and his delight in the unending novelty of scientific inquiry.
Broucke is remembered as a kind and generous man with a good sense of humor and
a fondness for his work and his students. Frequently, he and his family would
hold dinners for his students, which often featured barbeque and intense discussions
of mathematics and celestial mechanics. Throughout his life, he held a fascination
for the cosmos, motion of the stars, and heavenly bodies. His favorite book was
The
Little Prince by Antoine de Saint-Exupéry:
All men have the stars, but they are not the same things for different people. For some, who are travelers, the stars are guides. For others, they are no more than little lights in the sky. For others, who are scholars, they are problems. You—you alone—will have the stars as no one else has them.
To Roger Broucke, the stars were beautiful problems, whose luster and motion
could succumb to mathematics and scientific understanding.
<signed>
William Powers Jr., President
The University of Texas at Austin
<signed>
Sue Alexander Greninger, Secretary
The General Faculty
This memorial resolution was prepared by a special committee consisting of Professors
J. Tinsley Oden (chair), Linda Hayes and Cesar Ocampo.
