The 1980s & 1990s - Rodgers, Mould, MACHO and Dark Matter
In 1986 Alex Rodgers succeeded Don Mathewson as Director of Mount Stromlo and Siding Spring Observatories. Rodgers began his career in the 1960s and had completed his PhD at ANU under the supervision of former Stromlo Director Richard van der Riet Woolley before continuing his research in the United States.
Rodgers’ passion was optical engineering, and he loved getting his hands dirty in the Observatory Workshop. He was involved in the design and development of several pieces of equipment used at Stromlo and Siding Spring including the spectrophotometer for the Great Melbourne Telescope (50-inch Telescope) and double-beam spectrograph for the 2.3 Metre Telescope at Siding Spring. Rodgers is credited with moving the Observatory into the electronic era by designing and constructing photo-counting arrays and experimenting with adaptive optics (Bhathal, Sutherland & Butcher, 2014).
Arguably Rodgers’ most significant contribution during his directorship was the MACHO Project (MACHO being an acronym for Massive Astronomical Compact Halo Objects), a project focused on researching dark matter through the monitoring of light intensity of millions of stars in the Small and Large Magellanic Clouds and Galactic Bulge Fields. For researchers at Stromlo to be involved, Rodgers committed to refurbishing the Great Melbourne Telescope (50-inch Telescope), which had not been usable since suffering a mechanical failure a few years previous. Between 1992 and 1999 over 200,000 million individual measurements were made, significantly adding to our knowledge of variable stars and dark matter.
In late 1993, Jeremy Mould became Director of Mount Stromlo and Siding Spring Observatories. He had completed his PhD at ANU in 1977 and continued his work in Britain, the United States, and South America before returning to Stromlo with a five-year plan to build new facilities that would serve astronomy for years to come.
Mould championed Australia’s involvement with the European Southern Observatory, with a view to participating in the world’s premier astronomy project, the Very Large Telescope (VLT). Unfortunately, site testing found that Australia was unsuitable as a location for a VLT, making it even more important that Australian researchers partner with others.
Some of the projects Stromlo was involved with at this time included observational, design and construction work at the Gemini Observatory in Hawaii and Gemini South Telescope in Chile, with the technical skills of the Stromlo team second to none. Stromlo astronomers also became involved in the Joint Australian Centre for Astrophysical Research (JACARA) in Antarctica.
To enhance public outreach, Mould oversaw the construction of a new Visitor Centre at the Observatory, which attracted many thousands of visitors. Mould also joined the Australian Academy of Science’s National Committee for Astronomy and was responsible for chairing the Committee on Future Facilities.
During Mould’s tenure the Observatory was involved in three major projects with far-reaching implications for astronomical research. The first was research by Mould with Marc Aaronson and Rob Kennicutt of the University of Arizona, and Wendy Freedman of the Carnegie Observatories, relating to the Hubble Constant. The Hubble Constant is one of the greatest challenges in modern astronomy, a number that can determine how fast the universe is expanding and the age of the universe, although astronomers cannot reach agreement on this number. The team’s work on this was widely celebrated.
The second major project undertaken during the 1990s was Brian Schmidt’s research on the acceleration of the universe. Schmidt studied at the University of Arizona and Harvard University before joining Stromlo in 1995, where he led the High-Z Supernova Team in researching supernovae to determine the acceleration of the universe. In 1997, Schmidt, Saul Perlmutter and Adam Riess discovered that the expansion of the universe was accelerating. This was one of the most significant astronomical discoveries of the 20th century and they were awarded the Nobel Prize for Physics in 2011 for their work.
The third major project undertaken at Stromlo in the 1990s was Matthew Colless’ research on the dynamics of clusters of galaxies, specifically measuring dark matter. In 1993, Colless and Richard Ellis led the 2dF Galaxy Redshift Survey, using the Anglo-Australian Telescope (ATT) based at Siding Spring to study “both cosmology and the galaxy population with a precision and with a sample vastly superior to anything that had been done before” (Bhathal, Sutherland & Butcher, 2014). This research was highly significant in estimating dark matter.
These research projects undertaken by Stromlo and Siding Spring astronomers and their colleagues overseas were incredibly significant in the field of astronomy, demonstrating that the universe comprises a mix of dark matter and dark energy, with the latter driving a cosmic expansion.
Other important research produced at Stromlo during this period included John Norris and Mike Bessell’s research on stars with low metal abundances and Ken Freeman’s research on the formation of galaxies and globular clusters and dark matter. In 2001, Mike Bessell, Matthew Colless, Mike Dopita, Ken Freeman, Bruce Peterson and Jeremy Mould were all selected by the Institute of Scientific Information as Citation Laureates for their work.
Mould stepped down as Director in 2001 to take up the Directorship of the US National Optical Astronomy Observatory. John Norris served as Interim Director until the arrival of the Observatory’s first female Director in July 2002, Penny Sackett. Sackett would be the first female scientist to lead a major astronomical institution in Australia.
