By Matt Siegel
SYDNEY, Aug 6 (Reuters) - Australia on Wednesday awarded a contract to Dutch engineering firm Fugro to search the sea floor where missing Malaysia Airlines Flight MH370 is believed to have crashed, hoping to unlock modern aviation's greatest mystery.
Months of searches have failed to turn up any trace of the missing Boeing 777, which disappeared on March 8, carrying 239 passengers and crew shortly after taking off from Kuala Lumpur bound for Beijing.
The next phase of the search is expected to start within a month and take up to a year, focusing on a 60,000 sq km (23,000 square miles) patch of ocean some 1,600 km (1,000 miles) west of Perth.
Australian Transport Minister and Deputy Prime Minister Warren Truss said on Wednesday that Fugro was selected after "offering the best value-for-money technical solution" for the search.
"I remain cautiously optimistic that we will locate the missing aircraft within the priority search area," Truss told reporters in Canberra.
Investigators say what little evidence they have to work with suggests the aeroplane was deliberately diverted thousands of kilometres from its scheduled route before eventually crashing into the Indian Ocean off the coast of Western Australia.
Fugro will use two vessels equipped with side scan sonar, multibeam echo sounders and video cameras to scour the seafloor, which is close to 5,000 m (16,400 ft) deep in places.
The Dutch company is already conducting a detailed underwater mapping of the search area, along with a Chinese naval vessel.
"We haven't completed the mapping, so we are still discovering detailed features that we had no knowledge of, underwater volcanoes and various other things," said Martin Dolan, the head of the Australian Transport Safety Board, which is heading the search.
"We are finding some surprises as we go through."
Australia has set aside A$80 million to A$90 million for the search, already the most expensive ever undertaken. (1 US dollar=1.0749 Australian dollar) (Reporting by Matt Siegel and Lincoln Feast; Editing by Clarence Fernandez)