At the top of Powerhouse Parramatta, the rooftop observatory creates a new way to experience the night sky. Its telescope brings astronomy closer to the community, turning a rooftop into a place for curiosity, learning and discovery. That experience is made possible by an operable roof. When open, it clears the observatory completely, giving the telescope an unobstructed view, and when conditions change, it can be closed, protecting the equipment for the next clear night sky.

The observatory was conceived as a place for people to see the world differently and experience astronomy first-hand. Set on the rooftop of Powerhouse Parramatta, it creates an opportunity to engage with the stars, adding a new dimension to the museum.

To support this, the telescope needed a completely clear view of the sky and dependable protection when it is not in use. The retractable roof enables both. It opens fully to allow the telescope to look directly into the night sky, then closes to protect the equipment from the weather and secure the observatory. Its movement is what allows the space to shift between discovery and protection.

Tilt was engaged to develop the operable roof system that could reliably and safely support the needs of the observatory. The structural, mechanical and control systems were developed as one integrated design, creating a dependable system that supports the experience.

Tilt’s work at Powerhouse Parramatta extends beyond the observatory roof to the large hoisting doors within the museum’s main exhibition space. Together, the two projects show how Tilt brings ambitious architectural elements to life, working as a trusted design parter to deliver integrated systems to create experiences that matter.

The design strategy focused on making the movement of the roof feel simple, while resolving the complexity behind it. For the observatory to fulfil its purpose, the roof needed to disappear completely when the telescope was in use, creating an unobstructed connection to the night sky. At the same time, it needed to close reliably and provide protection when the observatory was not in use. The design therefore focused on creating a system that could move seamlessly between these two conditions without compromising the experience or the equipment.

The operable roof brings structure, mechanics, controls and weather protection together in one integrated system. Each element needed to work in sequence and respond reliably to changing conditions, resolving significant technical complexity behind a movement that feels simple.

A further consideration was electromagnetic interference. The observatory team was concerned that electrical noise from the AC motor and control system could interfere with the telescope’s sensitive instrumentation. To address this, the design incorporated noise control measures, including changes to the positioning of inductive components and cabling, alongside careful selection of hardware to manage harmonics generated by the motor controller and uninterruptible power supply (UPS).

The system uses a mild steel moving frame and sub-frame supported by a wheel-and-rail system, with rack-and-pinion transmission providing the movement. A motorised drive opens and closes the roof, while brush seals provide weather resistance when closed. The control system incorporates limit switches, brakes, encoders and feedback devices, with provision for integration with the building management system. Together, these elements allow the roof to operate reliably at the touch of a button, making the transition from a protected observatory to an open view of the night sky feel effortless.