The missing submersible lost contact with its mother ship on Sunday as it descended to the wreck of the Titanic.

As international search and rescue efforts continue, each passing second makes it less likely that the passengers on the Titan will be found alive as their oxygen supply is expected to run out by Thursday morning.

There are several possible outcomes – vessel found on the surface of the ocean, found on the ocean floor, its hull has been breached or that oxygen will be depleted and the rescue mission turns into a recovery mission.

While banging noises have been heard from the search area in the Atlantic, Carl Hartsfield of the Woods Hole Oceanographic Institute says it doesn’t mean they came from the missing sub.

“I can tell you with my experience with the acoustics, that there are sounds that sound man-made to the untrained ear, but I can assure you that the people listening to these tapes, are trained,” commented Hartsfield. “There are a lot of vessels in the area and they each make noise.”

OceanGate founder Stockton Rush, who is among the missing, said in a recently surfaced interview that he didn’t hire older men with military experience in his words “50-year-old white guys” but rather hired those in their 20s who he found to be more inspirational.