The letter describes the Powerhouse's present site in Ultimo as a "world class museum" with a building and exhibitions that have won many awards. Prominent businessmen, politicians, actors, architects and museum experts have signed an open letter urging the NSW government to reconsider plans to move the Powerhouse to western Sydney. "The project was a major investment for the people of New South Wales," the letter states. "That investment will be squandered if the museum's site is sold to developers." The letter's signatories say they support the building of a major new museum in Parramatta, "but to transport a pared-back, small scale Powerhouse would be folly". The signatories, who also include museum experts and architects, argue instead for a unique institution in Parramatta shaped by community consultation and which reflects the history, achievements and cultural diversity of western Sydney.

"Nowhere else in the world are governments moving major museums away from the heart of their cities," the letter states. "Instead they are building satellite museums to display the collections of their great museums. "The Powerhouse has the collections with which to create an original, exciting new museum for Western Sydney without abandoning its historic home." Seven former museum directors, a former arts minister and premier, trustees, benefactors, museum experts and 178 leading figures in Sydney's arts and business community added their names to the letter. It comes ahead of a parliamentary debate on the proposed Powerhouse move on February 25 that was triggered by a petition that gathered more than 10,000 signatures last year. South Sydney Rabbitohs chairman and former Powerhouse trustee Nick Pappas said a new museum in Parramatta "should not be built from the rubble of the Powerhouse Museum in Ultimo". "Make no mistake; this is a museum demolition plan, entailing the unprecedented sale of public cultural assets," Mr Pappas told Fairfax Media. "The Powerhouse Museum cannot be relocated from its iconic building and 130 years of education and cultural life in Ultimo."

Former president of the Powerhouse Museum, Marco Belgiorno-Zegna, said no one disputes the need for western Sydney to have "a growing cultural footprint". "But nowhere in the world has this been done by completely re-locating the associated key institution from its original location," he said. "It is critical that the Museum of Applied Science's Powerhouse location continue to remain a centre of excellence for the many curatorial areas that it supports. Mr Belgiorno-Zegna said relocating the Powerhouse would weaken the institution: "The move to Parramatta seriously risks weakening its undisputed skills and undermining one of the nation's key culturally institutions." Former trustee and museum consultant Kylie Winkworth said the sale of the Ultimo site raised the question of who owns the museum. "The Powerhouse Museum is not just government property available for disposal," she said. "Its collections have been endowed through thousands of donations and bequests."

She said the museum's relationships to donors, sponsors and supporters had not been recognised by the state government. A spokesman for Deputy Premier and Arts Minister Troy Grant said the government remained committed to delivering a "state-of-the-art" cultural institution in western Sydney. "The new museum in Parramatta will see more of the Powerhouse's collection utilised with the potential to have thousands of new and additional exhibits on display," he said. "We expect audiences, including school groups, will be lining up to visit the reimagined Powerhouse and it will be a great addition to the state's cultural offerings." The spokesman said the museum's collection would not be put at risk by the relocation: "The assertion that moving objects will destroy them is incorrect. The museum employs experienced, specialist staff to undertake collection management, security and conservation and the care of objects." He said 50,000 items from the Powerhouse's collection were already stored at the Castle Hill Discovery Centre, including Dick Smith's helicopter: "More items are expected to be moved from the Ultimo site once the Discovery Centre reopens this year."