Geology & Geophysics Tribute

Samuel J. Bame Jr. (1924–2014)

The pioneering space physicist made fundamental discoveries about space plasmas, including first measurements of solar wind structures and magnetic reconnection at the Earth's magnetopause.

By Bill Feldman, , and Michelle Thomsen

Samuel J. Bame Jr., one of the early pioneers in space physics, passed away 14 December 2014 in Albuquerque, N.M.

Beginning with his work in the Atomic Energy Commission’s Vela program, Sam emerged as one of the space community’s most successful, innovative, and prolific experimenters studying space plasma physics. His plasma experiments using various types of spherical section electrostatic analyzers were flown on the Vela 2, 3, 4, 5, and 6 satellites; on the Interplanetary Monitoring Platform 6, 7, and 8 satellites; on the International Sun-Earth Explorer 1, 2, and 3 satellites; on Ulysses and the Advanced Composition Explorer; and on a series of eight geosynchronous satellites. Together, these sensors have returned more than 82 satellite-years of data.

Sam’s experiments led to fundamental discoveries about space plasmas. These include the discovery of the plasma sheet and plasmoids in the geomagnetic tail as well as magnetic reconnection at the Earth’s magnetopause and in the solar wind. His instruments also detected heavy ions, non-Maxwellian structure in velocity distributions, thermal anisotropies, double ion beams, and coronal mass ejections in the solar wind, as well as the three-dimensional structure of the wind and its temporal and spatial evolution. In addition, his sensors discovered mechanisms of ion and electron heating at the Earth’s collisionless bow shock along with numerous quantitative characterizations of magnetospheric structure and dynamics at geosynchronous orbit.

Early Interest in Science

Sam was born on 12 January 1924 in Lexington, N. C. As a youth, he was fascinated by science, particularly astronomy. He began his college education at North Carolina’s Catawba College before entering the Army in 1943.

His aptitude for physics led to his selection for the Army Specialized Training Program at Pennsylvania State University in 1943–1944, and he served in the Proximity Fuse Program and Ordnance Technical Intelligence in the United States, the Philippines, and Japan in 1945–1946. After the war, he earned his bachelor’s degree in physics from the University of North Carolina and earned his master’s and Ph.D. degrees in nuclear physics from Rice University in 1951.

During his time at Rice, Sam won a Humble Oil Fellowship that allowed him to spend a summer interning at Los Alamos Scientific Laboratory in New Mexico. After graduation, he joined the scientific staff at Los Alamos, where he spent his entire professional career. His early years there were devoted to low-energy nuclear physics, but he shifted his attention to space physics as the Space Age began.

Space Physics at Los Alamos

During his 40-year career at Los Alamos, Sam served as principal investigator for more than 60 neutron and plasma experiments that he conceived, designed, and implemented. All 60 were flown in space.

In the first successful flight of NASA’s Scout rocket program, Sam made measurements of the relatively low-energy protons trapped in the outer Van Allen radiation belt. In a series of three rocket flights from 1959 to 1961, he made some of the first measurements of the neutron spectrum and neutron albedo above the atmosphere. The neutron detectors he developed for the Vela and follow-on satellite programs have provided continuous, critical monitoring support for the Nuclear Test Ban Treaty since 1963.

An Inspirational Scientist and Mentor

Sam was a mentor and an inspiration to younger scientists, such as the four of us, whose careers were launched and sustained by the rich data sets his instruments returned. The knowledge, skill, and care he brought to his work have left a truly rich legacy.

One of us (Dave McComas), whose desk was located in Sam’s lab, recalls learning about the design and development of flight hardware as a young physicist. It was a true apprenticeship, similar to that of a young tradesman moving into the master’s workshop to learn a craft.

Sam’s attention to the careful design of his instruments taught us the utility and fundamental need for controlling and measuring, where possible, all backgrounds that affect the data. He promoted an open scientific environment that often led to lengthy, animated discussions of central scientific questions raised by the data from his instruments. The resulting “chatter” in the halls was a distinguishing and vital trait of the space plasma team at Los Alamos.

Sam served on a number of advisory groups for NASA over the years, was a Fellow of Los Alamos National Laboratory and the American Geophysical Union, and authored more than 400 scientific papers.

He was preceded in death by his wife of 44 years and is survived by his three daughters and four grandchildren. Sam will be dearly missed by his many friends and colleagues.

—Bill Feldman, Planetary Science Institute, Tucson, Ariz.; Jack Gosling, Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder; Dave McComas, Southwest Research Institute, San Antonio, Texas; email: [email protected]; and Michelle Thomsen, Planetary Science Institute, Tucson, Ariz.

Citation: Feldman, B., J. Gosling, D. McComas, and M. Thomsen (2015), Samuel J. Bame Jr. (1924–2014), Eos, 96, doi:10.1029/2015EO032283. Published on 6 July 2015.

© 2015. The authors. CC BY-NC 3.0