Gillian Thomas, CEO of the under-development US$307m (€283.5m, £214.1m) Patricia and Phillip Frost Museum of Science in Miami, has suddenly retired from her position effective today (1 July).

Thomas, 72, is retiring after 13 years in charge of the science museum, which is undergoing a major expansion and redevelopment. Initially Thomas had planned to retire at 65, but delayed the move until she was confident the project would be realised.

“I believe that this is the right time for me to retire: as we approach the completion of the building project, now the task is to get the team in place that can carry the project through opening and focus on the future operations,” said Thomas in a statement.

Frank Steslow, who has acted as chief operating officer for the last eight years, will now assume the position of CEO. Steslow had worked as a scientist and non-profit executive for three decades, most recently as CEO of the Da Vinci Science Center in Allentown, Pennsylvania.

Thomas will remain an advisor on the project until its completion at the end of 2016. In February this year, the museum’s namesakes Patricia and Phillip Frost provided a bridge loan to keep construction going while the county explored other financial options. In April, Miami-Dade County approved a US$45m (€40m, £33.8m) bailout for construction costs.

The 250,000sq ft (32,225sq m) Grimshaw Architects-designed building – which is set to feature a 510,000 gallon aquarium, 3D planetarium and wildlife centre – is expected to open before the end of the year.

Speaking to Attractions Management in March, Thomas said the development would be 'the glue' for Miami’s waterfront, adding that not all exhibits would be there on day one, but that they would be added over time. “We see the museum as a kind of canvas, and some elements will come along later,” she said.