Obituary: Professor Lyman Spitzer
Mestel, Leon, The Independent (London, England)
Lyman Spitzer, astrophysicist, plasma physicist, and visionary, had an enormous influence through his own publications, his interactions with students and colleagues, and perhaps most of all through his enthusiastic but hard-headed advocacy of government-sponsored space astronomy and thermonuclear research. The Hubble Space Telescope, launched in 1990 and now feeding back its staggeringly detailed images, was essentially Spitzer's brainchild.
Spitzer was educated at Phillips Academy, in Andover, Maryland and at Yale University. He spent his first graduate year in Britain, as a Henry Fellow at Cambridge University. He records that the informal evening seminars given in Trinity College by S. Chandrasekhar were one major reason for his decision to work in astrophysics. Spitzer wrote his doctoral thesis at Princeton University with Henry Norris Russell as his adviser. His first position, as instructor in physics and astronomy at Yale from 1939, was interrupted by four years of war work at Columbia University, devoted largely to research in underwater sound.
His calibre was recognised in his appointment soon after as Russell's successor as Director of the Princeton University Observatory, a post he held from 1947 until his retirement. He and his colleague Martin Schwarzschild, whom he persuaded to join him, together built up a strong graduate teaching and research programme primarily in theoretical astrophysics, but with considerable emphasis on observational astronomy also. In an autobiographical essay "Dreams, Stars and Electrons" - first published in the Annual Review of Astronomy and Astrophysics in 1989 and also the title of a volume of his selected writings, published this year - Spitzer gives as one of his long-term goals the wish to understand the formation of stars from the interstellar gas in our own and in other galaxies. Over the decades, he and his collaborators studied in detail the physics of the interstellar gas and the associated dust and of the magnetic field permeating the gas. Of particular interest is the study of the tendency of dust grains to be aligned by the magnetic field, with an effect on starlight that was the first clue to the existence of a sizeable galactic magnetic field. He summarised his own work and that of others in a valuable text, Physical Processes in the Interstellar Medium (1978). Already in 1946, Spitzer had written a paper pointing out the great advantages for astronomy of observations made from an orbiting space telescope, both through extending the accessible parts of the electromagnetic spectrum, and avoiding the inevitable distortions caused by the earth's atmosphere. The 1957 launch of the first Soviet sputnik gave an enormous impetus to the US space programme. With a contract from Nasa, a group of Princeton scientists under Spitzer's chairmanship explored both the possibilities of research on interstellar matter, through observation in the ultra-violet, and the engineering requirements for an astronomical satellite. Spitzer wrote that perhaps the high-point of his career was the day in 1972 when the ultra-violet spectrometer in the orbiting Copernicus satellite was switched on and immediately began operating as planned, so opening up a new chapter in the study of the interstellar gas. In its nine years of operation, the instrument yielded much information of major importance, confirming the theoretical prediction of giant clouds of molecular hydrogen, discovering regions in the galactic disk with a million-degree temperature and measuring the ratio of deuterium (an isotope of hydrogen) to normal hydrogen, of crucial importance for the Big Bang cosmological model. But Spitzer's vision had already gone further; he dreamed of a general purpose telescope with a mirror in the three- metre class. Even after the doubts and hesitation of other astronomers had been assuaged, much diplomatic skill was needed before the go-ahead from Congress for the Hubble Space Telescope was gained in 1977. …