Herbert Friedman died of cancer at his home in Arlington, Virginia on 9 September 2000. He was born in Brooklyn, New York on 21 June 1916, the second of three children of Samuel and Rebecca Friedman.
He was a recognized pioneer in the space sciences for his contributions to solar physics, aeronomy and astronomy but he also made fundamental advances in the application of X-rays to material analysis. He was also a great science statesman and a public spokesperson for science. During his lifetime, he captured virtually every science award including the Eddington Medal of the Royal Astronomical Society, the National Medal of Science, the William Bowie Medal of the American Geophysical Society, the Henry Norris Russell Lectureship of the American Astronomical Society and the Wolf Foundation Prize in Physics. He was elected a member of the National Academy of Science in 1960. His service to science included membership on the President's Science Advisory Committee, the General Advisory Committee to the Atomic Energy Commission, the Space Science Board of the National Academy of Sciences and the Governing Board of the National Academy of Sciences.
Friedman had a remarkably diverse career as a scientist. He arrived at the Naval Research Laboratory (NRL) in 1940 after completing his PhD at John Hopkins University. Until around 1950 Friedman's research activities were dedicated to laboratory X-ray analysis, an area in which he published 25 papers and was granted 50 patents. In 1945, Dr. Friedman received the first of a long line of awards, the Navy's Distinguished Civilian Service Award, for the wartime development of a technique for cutting and tuning radio frequency crystals by using their Bragg reflection characteristics.
By itself, this record distinguishes Friedman as a gifted scientist. But by 1950, Friedman had switched to the newly emerging field of observations from space using sounding rockets. Fortuitously, Friedman was in the Division at NRL headed by E. O. Hulburt, a pioneer in the study of the upper atmosphere. Friedman's first experiment, flown on the 49th V2 rocket launched from White Sands, was conducted in 1949 and comprised observing solar X-ray and ultraviolet radiation using Geiger counters. Rocket experiments conducted up to that time were largely observations but Friedman tried to answer a question that had arisen almost 50 years earlier, "What was the source of the ionization of the upper atmosphere?" Friedman continued his solar and atmospheric observations for another decade. It was a heroic period of rocket science. Friedman managed to arrange for the launch of rockets from shipboard; one, a series of rockoons (small rockets carried up on balloons and then launched) captured a solar flare and demonstrated that the emission was principally in the form of X-rays; another, a series of Nike-Asp rockets fired during the 1958 total solar eclipse, demonstrated that the X-ray emission extended far beyond the visible disk of the sun and was concentrated in small regions on the surface. During this period of time he also obtained the first image of the sun with a pinhole camera, flew the first Bragg spectrometer for measuring hard X-rays and developed and flew the first solar satellite, SOLRAD, that traced out the solar X-ray flux during a solar cycle. The SOLRAD instruments are the model for the solar monitoring instruments that NOAA places on its GOES satellites.
Friedman switched to 'nighttime' astronomy in 1955 with a rocket flight using collimated Geiger counters sensitive in the mid-ultraviolet that revealed significant emission associated with the Milky Way. Following the report of the discovery of cosmic X-ray sources in 1962, Friedman responded with a rocket flight in early 1963 that unambiguously confirmed the presence of discrete sources of X-rays and of a diffuse X-ray background. In 1964, he conducted what has been regarded as one of the more noteworthy single experiments conducted with sounding rockets, the observation of the Crab Nebula as it was being occulted by the moon. This experiment demonstrated positively that the Crab Nebula was a source of X-rays and that the emission was associated with the nebula itself. Actually, the result was a considerable disappointment to Friedman who was hoping to observe emission from a point-like neutron star near the center of the nebula that might have been the stellar remnant of the supernova explosion responsible for the creation of the nebula.
Friedman's career as a scientist/statesman began around 1960 and involved his participation, membership and office tenure in almost every organization, study, and advisory panel dealing with the space sciences. His career as a writer began in 1975 with the appearance of his book, The Amazing Universe, followed in 1985 by The Sun and Earth and in 1990 by The Astronomer's Universe.
Friedman was highly regarded and extremely influential as a science adviser. Frank Press tells the story that during the administration of President Carter a choice needed to be made between a Halley Comet Mission and the Gamma Ray Observatory. Friedman was approached for an opinion. He responded that a Halley mission would be very popular and return spectacular results, but observing gamma rays was more fundamental. The Carter administration did, in fact, opt for the Gamma Ray Observatory.
Other obituaries have been prepared for publication in Physics Today, EOS and by the American Philosophical Society.
Photo courtesy of the Naval Research Laboratory