Riccardo Giacconi

Biography

On 12 June 1962 an Aerobee rocket carrying an X-ray detector was launched from a test range. The aim was something else: to photograph the Moon in X-rays. The Moon could not be seen, but the instrument recorded a bright object in the constellation Scorpius. It was named Scorpius X-1.

Giacconi was thirty at the time.

He was born on 6 October 1931 in Genoa, the son of Antonio Giacconi, who owned a small firm, and Elsa Canni, a teacher of physics and mathematics. When the boy was about eight his parents separated, and he grew up with his mother in Milan. He studied physics at the University of Milan and defended his dissertation in 1954; his teacher in cosmic-ray work is said to have been Giuseppe Occhialini. He then stayed on there as an assistant.

In 1956, on a Fulbright fellowship, he went to the United States, to Indiana University in Bloomington, and in 1958 moved to Princeton. His departure is linked to advice from Occhialini; I cannot check this against documents. His work up to 1959, as he said himself, had gone badly. The turning point was joining American Science and Engineering in Cambridge, Massachusetts, a company founded by Bruno Rossi to carry out research on government funds. Giacconi called his years there the most productive of his life. From 1959 to 1962 he took part in preparing instruments for twenty-three rockets, six satellites and one aircraft flight. In 1966 he was elected to the company’s board of directors, and from 1969 he was its vice-president.

Cosmic X-rays are absorbed by the Earth’s atmosphere, so they can be observed only from rockets and satellites. That explains the whole line of his engineering work: detectors on rockets in the late 1950s and early 1960s, then the Uhuru satellite, launched in 1970. It carried out the first survey of the whole sky in X-rays and found 339 sources, among them Cygnus X-1 and Vela X-1. Next came the HEAO-2 satellite, named the Einstein Observatory: it was launched on 12 November 1978 and was the first fully imaging X-ray telescope in space.

In 1973 Giacconi moved to the Harvard–Smithsonian Center for Astrophysics in Cambridge, where he headed the high-energy astrophysics division. From 1981 he was the first permanent director of the Space Telescope Science Institute in Baltimore, the centre that runs observations for Hubble, and he remained in that post until 1993. At the same time he taught at Johns Hopkins University: as professor of physics and astronomy from 1982 to 1997, then as research professor.

From 1993 to 1999 he was Director General of the European Southern Observatory, headquartered in Garching near Munich; the Very Large Telescope was built during his tenure. From 1991 to 1999 he also held a professorship in Milan. After returning to the United States in 1999 he became head of Associated Universities, Inc., and led it until 2004, during the early years of the ALMA radio telescope array. In the 2000s he was principal investigator of the Chandra Deep Field-South project on NASA’s Chandra X-ray Observatory.

He did not design ROSAT, the German X-ray satellite, but he helped bring in American funds for it, including a free launch. For the German ministry this mattered: it required international cooperation. In 1992 Giacconi signed the “World Scientists’ Warning to Humanity”.

Awards came from the 1960s on: the Helen Warner Prize for Astronomy (1966), membership of the National Academy of Sciences (1971), the Bruce Medal (1981), the Gold Medal of the Royal Astronomical Society (1982) and the Wolf Prize in Physics (1987). He received the 2002 Nobel Prize in Physics for pioneering contributions to astrophysics that led to the discovery of cosmic X-ray sources; the other half was shared by Raymond Davis Jr. and Masatoshi Koshiba for neutrino astronomy. The National Medal of Science (2003) and the Karl Schwarzschild Medal (2004) followed. An asteroid, 3371 Giacconi, is named after him.

Giacconi died on 9 December 2018 in San Diego.