Biographical Profile - Dr. Robert Stone

Robert G. Stone has played a major role in the field of solar and planetary radio astronomy research over the past three decades. Since coming to Goddard Space Flight Center in 1962, he has served as Principal Investigator for six satellite radio experiments, including RAE-I, RAE-II, IMP-6, and Ulysses, as well as a number of sounding rocket radio experiments. For the two Radio Astronomy Explorer (RAE) Satellites, he also served as Project Scientist. In addition, he has been a principal Co-Investigator on several satellite radio experiments, including the highly-successful Helios and ISEE-3/ICE spacecraft.

He has authored or co-authored more than one hundred papers analyzing the observations from these missions. His early work pioneered the study of low frequency radio emissions from the terrestrial magnetosphere, the Sun, the interplanetary medium, and the galaxy. More recently, the ISEE-3/ICE spacecraft mission (1978-1992) provided observations of solar radio bursts with unprecedented sensitivity. Dozens of radio bursts associated with interplanetary shocks were catalogued and their key diagnostic role in linking major solar flare activity to geomagnetic storms was demonstrated. Observations of radio bursts produced by solar flare electrons provided a clearer understanding of radio propagation in the inner interplanetary medium. The high sensitivity and excellent calibration of the ISEE-3 radio receiver made possible for the first time an accurate explanation of the spectrum observed by a sensitive radio experiment immersed in a low density plasma. This technique, now known as thermal noise spectroscopy, permits the accurate determination of electron density and temperature without errors introduced by spacecraft charging. It has been successfully applied to the measurement of solar wind densities, as well as to comet densities when the ISEE-3/ICE spacecraft was redirected to achieve the first rendezvous with a comet (Giacobinni-Zinner).

Among his most recent contributions to the fields of space radio and plasma wave observations have been as Principal Investigator of the Ulysses Unified Radio and Plasma Wave Experiment (URAP). The Ulysses spacecraft is currently on a mission to explore the regions of interplanetary space over the poles of the Sun. The analysis of radio waves from solar flare electrons and interplanetary shocks provide important diagnostics of solar activity. The observations of plasma waves out of the ecliptic play a key role in understanding the dynamics of particles in these previously-unexplored regions. Furthermore, the flyby of the planet Jupiter for the required gravitational redirection of the spacecraft's trajectory permitted the URAP experiment to obtain a bounty of new scientific results. The discoveries have included several new classes of Jovian radio bursts (among which are two varieties of radio bursts whose striking periodic occurrence is currently unexplained), the locations of several Jovian radio burst sources using the spinning-spacecraft technique, and the detection of ultra-low frequency waves of sufficient strength to explain the particle precipitation responsible for certain Jovian aurora. These results have provided a clearer understanding of the Jovian magnetosphere and raised important new questions.

Robert Stone played a key role in the analysis of data from the Ulysses URAP mission and the WIND spacecraft (for which he was a Co-investigator with the WAVES radio and plasma wave experiment).