The search for missing Malaysia Airlines flight MH370 has entered a new phase with the Australian government selecting a Dutch consulting firm to conduct a deep-water operation that could take up to a year.

Two massive vessels equipped with deep-water vehicles and expert personnel will cross the southern Indian Ocean, Australian Deputy Prime Minister Warren Truss said Wednesday.

The vessels, which will set off in September, could cover more than 20,000 square miles. The search will cost an estimated $48 million, according to CNN, with Australia taking the lead and the Malaysian government covering an unspecified portion of the bill.

“I remain cautiously optimistic that we will locate the missing aircraft within the priority search area,” Truss said at a news conference. “This search will obviously be a challenging one. We would hope obviously to find the aircraft on the first day, but it could in fact take a year to search the entire area, and of course weather conditions will have an impact on what time will be required to complete the task.”

Friday marks the five-month anniversary of MH370’s mysterious disappearance with 239 passengers on board. The hunt has been plagued by bad weather and technical problems.