When the CSIRO’s 64-metre Parkes “Murriyang” Radio Telescope was commissioned in 1961, it was only expected to operate for 20 years. Today, having more than tripled its life expectancy, it still operates as one of the world’s finest single-dish radio telescopes and contributes to cutting-edge scientific research and communications.
The Parkes telescope is distinguished by innovative design features — it was, for instance, the first large radio telescope to be mounted from the centre, like an inverted umbrella — but these features alone do not explain its longevity. Rather, the telescope has been constantly upgraded over the years, reconfigured for new uses and adapted for modern requirements.
Paradoxically, it is in many ways a young telescope; the only parts of the instruments that are actually 60 years old are the concrete and steel it is made from. As a result, the Parkes telescope is more than 10,000 times more sensitive today than when it was built.
The Parkes Observatory’s first computer was not installed until 1968; when the telescope was first commissioned, the most common recording device was a chart recorder and analysis was performed with a slide-rule. A PDP-9 with a paper tape output, the computer appeared in the 2000 film The Dish, which told the story of the observatory’s role in the 1969 Moon landing.
Today, all the telescope’s functions have been computerised: the data it collects is digitised and stored onto magnetic disks before being transported around the country and the world, via dedicated fibre-optic lines with a one gigabyte per second capacity. If required, this can be upgradable to 10 gigabytes per second. A typical observing session today can record several terabytes of data.
The telescope’s receiving systems have also been extensively upgraded over the years. When commissioned, simple dipole receivers were used to detect the radio waves at the focus. These essentially operated at room temperature; later, vastly more sensitive and cryogenically cooled receivers were developed that operate at around 20 K (–253.15 degrees Celsius).
The telescope’s technology got another boost in 1997, when its multi-beam receiver was commissioned. Until then, conventional receivers could only detect radio signals coming from a single point in the sky.
These single-feed receivers would sit at the focus of the parabolic dish, only detecting signals received at that point. However, the telescope has a focal plane — that is, a region around that focus point where the signal is still quite strong.
By placing several receivers on the focal plane, multiple adjacent points on the sky can be observed at once. A new focal plane array receiver with 13 feeds allowed astronomers to “see” 13 points simultaneously on the sky and to conduct surveys 13 times faster than in the before.
While contemporary multi mega-pixel optical cameras outclass this, the technology greatly improved upon single-pixel, conventional radio receivers. The multi-beam receiver rejuvenated the Parkes telescope and led to several groundbreaking surveys that doubled the total known number of pulsars, including the discovery of the only known double pulsar system in 2003.
It also allowed astronomers to probe the Universe and plot the positions of galaxies out to 300 million light years and to peer through the obscuring dust of the Milky Way to see what lay behind for the first time. It revolutionised the way radio telescopes conducted surveys.
Upgrades to the way the telescope is operated have also enhanced its usefulness. Since the 1980s, astronomers have been able to control the instrument via computer, rather than requiring dedicated operators to use complicated manual equipment. By the late 2000s, internet speeds had advanced enough that astronomers were able to connect to the telescope and operate it from anywhere in the world, including their own homes.
As a result of these advances and efficiencies, the telescope has found continuing uses in the present day, many of which have progressed beyond its original purpose and involve discoveries and research unimagined in the 1960s.
Extremely fast and incredibly distant
Fast radio bursts (FRBs) for instance are sudden, single bursts of radio energy that last only a few milliseconds. Their origin is a mystery, yet they appear to come from extragalactic sources, billions of light years from the Earth, implying that the energy release is enormous.
The first FRB was discovered at Parkes in 2007 by astronomer Duncan Lorimer and his colleagues. Lorimer had been searching through archived data taken with the multibeam receiver in 2001, looking for giant pulses from pulsars.
Instead, he came across an ultra-bright burst from a single point in the sky. The dispersion of the signal indicated it was very distant. Over the next few years, more of these bursts were found in the archived data, coming from other points in the sky, and in new observations. Slowly, other observatories discovered more FRBs, and for the first ten years, Parkes held the record for the number found.
To further study these objects — and much more — a new suite of radio receivers was built for Parkes, including an ultra-wideband receiver that will operate over many times the frequency range of existing receivers, and a phased array feed (PAF) receiver developed by CSIRO.
PAFs are many little antennas placed on the focal plane of the telescope. Each of the antennas can be linked together, or phased, in such a way that many points can be observed on the sky, at once.
In 2020, work began on a cryogenically cooled PAF specifically for the Parkes telescope. This receiver will be even more sensitive than the existing PAFs and will be capable of projecting 72 beams onto the sky. Its installation began in late 2022 and it will enhance the search for FRBs.
Listening and looking
The Parkes telescope is also playing an essential role in the scientific integrity of the Breakthrough Prize Foundation’s Search for Extra-Terrestrial Intelligence (SETI) project. Known as Breakthrough Listen, this ten-year, US$100 million project will use the Parkes Observatory as part of its survey until 2026.
Though it was designed as an astronomical instrument, the Parkes Observatory also has a long history of participating in outer-space tracking efforts, which continues today. During the telescope’s construction, the CSIRO agreed to include the telescope in NASA’s fledgling Deep Space Network. The CSIRO agreed that whenever a strong, reliable signal was required, especially during critical moments like planetary flybys or landings, then the Parkes telescope would support the missions for those brief periods.
Since then, Parkes Observatory has helped track such missions as Mariner 2’s Venus fly-by, Mariner 4’s Mars voyage, the Apollo lunar landings of 1969 to 1972, as well as Voyager 2’s journey through the Solar System and a European Space Agency mission to Halley’s Comet.
More recent missions to Jupiter, Mars — including the Curiosity rover — and Saturn’s largest moon Titan have followed. This year Parkes Observatory will track the next generation of commercial lunar landers.
The improvements and upgrades that have allowed the Parkes telescope to continue useful operation today has maintained its status as Australia’s premier scientific instrument. It endures as an iconic telescope with a great legacy of world-class science and discovery.
Michael Taylor FIEAust CPEng(Ret) tells create, “Engineering is an evolutionary process. What we do today is achieved off the shoulders of those who have gone before. The evolution of the Parkes telescope is a great example of just that.
“Engineering Heritage Australia is a community within Engineers Australia with the goal of promoting the recognition and understanding of our heritage to the advancement of the practice of engineering. By recognising where we have come from we can further inspire our future.”
This story is based on an article that was published in the ‘EHA Magazine’ in September 2022. This is a free magazine covering stories and news items about industrial and engineering heritage in Australia. The magazine is published online and is available from the Engineering Heritage Australia website.