Herbert S. Bridge

Herbert Sage Bridge (1919-1995) was an American physicist who developed the first instruments to measure plasma in interplanetary space and made significant contributions to cosmic ray research. He earned his PhD in physics from MIT in 1950 under Bruno Rossi's supervision after working on wartime projects at Princeton and Los Alamos Laboratory. His early research focused on cosmic rays. Beginning in 1958, Bridge developed the modulated-grid Faraday cup with Rossi, creating the first instrument capable of detecting dilute space plasma. The instrument flew aboard Explorer 10 in 1961 and was adapted for plasma science experiments on multiple spacecraft, including the Voyager program and Parker Solar Probe.

Biography Bridge was born in Berkeley, California, in 1919. He studied chemistry at the University of Maryland (BSc, 1941), and then worked at the National Defense Research Council Separation Project at Princeton and the Los Alamos Laboratory during the war. He got a PhD in physics from MIT, working on cosmic ray research under Bruno Rossi's supervision (1950) (before MIT, Bridge worked with Rossi at Los Alamos). His research "focused on nuclear interactions produced by cosmic ray particles and on the new, unstable particles that result". Among his results was the "discovery of the positive K-meson and the cloud chamber observation of a cosmic-ray event interpreted tentatively as the annihilation of a heavy antiparticle". In 1965, he became an associate director of the MIT's Center for Space Research, became its director in 1978, and retired in 1984.

Explorer 10 satellite. The white circular cap covers the opening of the MIT Faraday cup. Bridge started to work on space plasma in 1958;

The modulated-grid Faraday cup for the Explorer 10 (1961) was the first of Bridge's spacecraft instruments. It was the first instrument that detected dilute plasma in interplanetary space.

Personal life Bridge had two sons and a daughter. He enjoyed "cars, photography, mountaineering and the out-of-doors", and visited many high-altitude laboratories through his interest in cosmic rays and mountains.

Awards member of the American Geophysical Society Fellow of the American Geophysical Union and the American Academy of Arts and Sciences member of Phi Beta Kappa 1974 NASA Exceptional Scientific Achievement Medal

Selected publications