A search and rescue operation is currently taking place in the Atlantic Ocean for a submersible vessel that was exploring the wreckage of the Titanic. According to Rear Admiral Chris Parry, a retired Royal Navy officer and former chair of the British Government’s Marine Management Organisation, OceanGate was reportedly informed about the structural defects of the submersible five weeks ago.

The submersible, named Titan, was reported as overdue approximately 435 miles south of St. John’s, Newfoundland. The search effort involves the Canadian Coast Guard, U.S. Coast Guard, and other resources. The support vessel lost contact with the submersible about an hour and 45 minutes after it submerged on Sunday morning.

The submersible has a 96-hour oxygen supply, and rescuers are working to deploy a remotely operated vehicle to the location. One of the mission specialists on board, Hamish Harding, a U.K. businessman, had been looking forward to conducting research at the Titanic site. The primary objective of the expedition was to document the deterioration of the Titanic wreck, which has been impacted by metal-eating bacteria. The remote location and limited options beyond the continental shelf pose significant challenges to the rescue operation.

In a separate incident, David Pogue, who was on the missing submersible last summer during a similar mission for CBS, reports that the craft lost contact with the mother-ship for two and a half hours due to a failure in its text-messaging system. GPS cannot function accurately or at all underwater.