Malaysia’s Transport Minister said Thursday that they will intensify the search with a mini-submarine for the defunct Malaysia Airlines aircraft.

The autonomous underwater vehicle Bluefin-21 that tracks the depths on the part of the Indian Ocean in search of the aircraft that disappeared March 8 conducted its first successful exploration.

Two previous missions had to be aborted due to technical difficulties.

Meanwhile, scientists in Western Australia tested samples from a stain of oil in the area to see whether it belonged to the Boeing 777-200 with 239 people aboard flying between Kuala Lumpur and Beijing.