As tentative steps were taken on the surface of the moon, the intrepid Apollo crews positioned five retroreflectors pointing back to planet Earth. Over time, these mirrors proved to be a critical element in determining our precise position, ultimately leading to advancements in the global positioning systems we take for granted today.
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In 1974 the mountains of Namadgi National Park became the home of an ambitious scientific project in which pin-point lunar measurements operating within the realms of nanoseconds was established. Nestled high in the tranquility of the Orroral Valley, looking down upon a NASA Tracking Station, an impressive domed building was built, capable of calculating a thousand millionth-part of a second.
It was precise, it was cutting edge.
For the next quarter of a century, the Orroral Geodetic Observatory proved to be an incredible scientific window gazing on our universe, one of only two such stations in the southern hemisphere. When the observatory fired a laser pulse to the moon, it took 2.5 seconds to travel 385,000 kms, bouncing off a mirror and travelling back to Earth. The observatory’s exceedingly accurate measurements improved our scientific understanding of the earth’s rotation, movement of tectonic plates and continental drift.
So accurate were the astrophysical measurements that four caesium atomic clocks were installed. The time set by these clocks contributed to the determination of Universal Time around our globe. One clock was designated as our national primary standard of time; its purpose was to keep Australian time accurate to 100 nanoseconds. It was the ultimate time keeper. It was the benchmark by which time was set.
But in 1998, it was decommissioned: the 18 tonne astronomical telescope was removed, atomic clocks reallocated, satellite dishes turned off. The observatory stood as time marched by and some 20 years later, life is being breathed back into the grand, old building.
Under the stewardship of Parks Field Officer Mark Rodden, we are reopening the precinct to the public to learn about the amazing cosmological role the observatory once played.
We are reaching out to our community to hear the stories of those who fired the lunar laser, kept watch over the atomic clocks and who professionally contributed to this remarkable chapter of our universal history.
If you once worked at, or know someone connected with, the Orroral Geodetic Observatory, please drop us a line at Namadgi.national.park@act.gov.au.
- Brett McNamara is with ACT Parks & Conservation Service.
